tag:blogger.com,1999:blog-5675478093195571152024-03-21T16:33:42.220+05:30Telecom Articles by Samir AmberkarSamir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comBlogger197125tag:blogger.com,1999:blog-567547809319557115.post-57412295394563051292023-12-16T18:27:00.000+05:302023-12-16T18:27:26.289+05:30INDEX<body class=bodystyle>
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INDEX
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<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/p/about.html">About</a>
</b>. . . . .<br></td>
<td width=50px align=right valign=top class=pagenumf><b>
1
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<font class=secnumf>1</font> <font class=categoryf>Telecom</font>
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<font class=secnumf>1.1</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/01/wp-base-station-scheduling-p1.html">Base Station Scheduling</a>
. . . . .</td>
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2
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<font class=secnumf>1.2</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/01/wp-tomorrows-mobile-wireless-p1.html">Tomorrow's Mobile Wireless</a>
. . . . .</td>
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7
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<font class=secnumf>1.3</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/02/wp-theoretical-data-rates-for-lte-p1.html">Theoretical Data Rates for LTE</a>
. . . . .</td>
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9
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<font class=secnumf>1.4</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/05/wp-lte-nas-security-p1.html">LTE NAS Security</a>
. . . . .</td>
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16
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<font class=secnumf>1.5</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/06/wp-lte-nas-security-2-p1.html">LTE NAS Security - 2</a>
. . . . .</td>
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22
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<font class=secnumf>1.6</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/06/wp-lte-allocations-explained-p0.html">LTE Allocations explained</a>
. . . . .</td>
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30
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<font class=secnumf>1.7</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/07/wp-lte-overview-p0.html">LTE Overview (<i>a presentation</i>)</a>
. . . . .</td>
<td width=50px align=right valign=top class=pagenumf>
50
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<font class=secnumf>1.8</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/08/wp-lte-allocations-explained-2-p1.html">LTE Allocations explained - 2</a>
. . . . .</td>
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69
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<font class=secnumf>1.9</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/12/wp-lte-ue-nas-overview-p0.html">LTE UE NAS Overview (<i>a presentation</i>)</a>
. . . . .</td>
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74
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<font class=secnumf>1.10</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2018/08/wp-cv2x-overview-p0.html">A look at CV2X for Modem developer (<i>a presentation</i>)</a>
. . . . .</td>
<td width=50px align=right valign=top class=pagenumf>
91
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<font class=secnumf>(Published on Sasken.com)</font> <a class=ilinkf href="https://www.sasken.com/insights/white-papers/c-v2x-autonomous-resource-selection-explained">CV2X Autonomous Resource Selection Explained</a>
. . . . .</td>
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(11)
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<font class=secnumf>1.11</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2018/08/wp-perl-language-n-secret-p0.html">Perl:A language and Secret behind productivity (<i>a presentation</i>)</a>
. . . . .</td>
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115
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<font class=secnumf>1.12</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2018/11/wp-5g-intent-p1.html">5G Intent</a>
. . . . .</td>
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124
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<font class=secnumf>1.13</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2018/12/wp-5g-intent-pre-p0.html">5G Intent for Modem developer (<i>a presentation</i>)</a>
. . . . .</td>
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132
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<font class=secnumf>1.14</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2019/01/wp-cdf-p1.html">CDF (Cumulative Distribution Function)</a>
. . . . .</td>
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142
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<font class=secnumf>1.15</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2020/01/wp-het-net-small-cells-in-3gpp-p1.html">Heterogeneous Networks, Small Cells in 3GPP</a>
. . . . .</td>
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144
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<font class=secnumf>1.16</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p1.html">Understanding LTE Cat M1 (eMTC)</a>
. . . . .</td>
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150
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<font class=secnumf>1.17</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p1.html">Scheduling or Radio Resource Selection</a>
. . . . .</td>
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157
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<font class=secnumf>1.18</font> <a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p1.html">MIMO for 3GPP L2 RAN Developer</a>
. . . . .</td>
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161
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<font class=secnumf>1.19</font> <a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/10/wp-ulpc-p1.html">Introduction to Uplink Power Control</a>
. . . . .</td>
<td width=50px align=right valign=top class=pagenumf>
167
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<font class=secnumf>1.20</font> <a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p1.html">MIMO for 3GPP L2 RAN Developer - 2</a>
. . . . .<font style="background-color:yellow"><i> New </i></font></td>
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171
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<font class=secnumf>2</font> <font class=categoryf>Software</font>
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<font class=secnumf>2.1</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/01/wp-search-engine-concepts-and-design-p1.html">Search Engine Concepts and Design</a>
. . . . .</td>
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178
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<font class=secnumf>3</font> <font class=categoryf>Support</font>
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<font class=secnumf>3.1</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2012/01/wp-elements-of-project-management-p1.html">Elements of Project Management</a>
. . . . .</td>
<td width=50px align=right valign=top class=pagenumf>
179
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<font class=secnumf>3.2</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.in/2012/02/royal-enfield-classic-500-efi-bullet.html">Royal Enfield Classic 500 EFI Bullet Rocks !</a>
. . . . .</td>
<td width=50px align=right valign=top class=pagenumf>
185
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<font class=secnumf>3.3</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.in/2015/08/wp-triumph-bonnie-review.html">Hey Triumph Bonneville ! - Review</a>
. . . . .</td>
<td width=50px align=right valign=top class=pagenumf>
193
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<font class=secnumf>3.4</font> <a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2015/09/wp-cleaning-triumph-bonneville.html">Cleaning Motorcycle - Triumph Bonneville !</a>
. . . . .</td>
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194
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<font class=secnumf>3.5</font> <a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2022/04/search-music-album.html">Search Music Albums</a>
. . . . .</td>
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195
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</body>Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-23015810552620147002023-12-16T18:22:00.002+05:302023-12-18T06:53:55.800+05:30wp-mimo2-p7<!-- copy FROM here -->
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer - 2</font><br><br>
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<br><font class=header1>Abbreviations</font><br>
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CSI<br>
CSI-RS<br>
DM-RS<br>
FR1<br>
MCS<br>
MIMO<br>
MU-MIMO<br>
PMI<br>
PRBs<br>
SRS<br>
SU-MIMO<br>
TTI<br>
</td><td class="contentf">Channel State Information<br>
Channel State Information/Indicator Reference Signal<br>
Demodulation Reference Signal<br>
Frequency range 1 (till 6 GHz)<br>
Modulation and Coding Scheme<br>
Multiple Input Multiple Output<br>
Multiple User MIMO<br>
Precoding Matrix Indicator<br>
Physical Resource Blocks<br>
Sounding Reference Signal<br>
Single User MIMO<br>
Time to Transmit Interval<br>
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<br><font class=header1>References</font><br>
<font class=contentf><br></font>
<font class=contentf>1. <a href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.214/">3GPP TS 38.214 Physical layer procedures for data</a><br></font>
<font class=contentf>2. <a href="https://us.artechhouse.com/Digital-Beamforming-in-Wireless-Communications-P1033.aspx">Digital Beamforming in Wireless Communications by Litva</a><br></font>
<font class=contentf>3. <a href="https://mathscinotes.wordpress.com/2012/01/20/beamforming-math/">Beamforming math</a><br></font>
<font class=contentf>4. <a href="http://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#LTE-Erik">3G Evolution: HSPA and LTE for Mobile Broadband</a><br></font>
<font class=contentf>5. <a href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-Dahlman">5G NR: The Next Generation Wireless Access Technology</a><br></font>
<font class=contentf>6. <a href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-bullets-johnson">5G NR in bullets</a><br></font>
<font class=contentf>7. <a href="https://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_87/Docs/R1-1612661.zip">R1-1612661 Advanced CSI Codebook Structure</a><br></font>
<font class=contentf>8. <a href="https://idv.sinica.edu.tw/ctli/tp/cross_polarization_def.pdf">Definition of cross-polarisation</a><br></font>
<font class=contentf>9. <a href="https://repository.library.carleton.ca/downloads/mk61rh58v">A Robust Modular Oversampling Beamformer Architecture</a><br></font>
<font class=contentf>10. <a href="http://uu.diva-portal.org/smash/get/diva2:1412235/FULLTEXT01.pdf">Beamforming in 5G mm-wave radio networks</a><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p1.html">1</a>
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<td align=center title="Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p2.html">2</a>
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<td align=center title="Precoding for Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p3.html">3</a>
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<td align=center title="Beamforming and MIMO" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p4.html">4</a>
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<td align=center title="CSI Codebook" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p5.html">5</a>
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<td align=center title="Feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p6.html">6</a>
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<td align=center class=pcurr>7
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-67346616634368140272023-12-16T18:21:00.012+05:302023-12-18T06:55:16.997+05:30wp-mimo2-p6<!-- copy FROM here -->
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer - 2</font><br><br>
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<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEi8P9yp6PElcmmto1ib7l2hNQG9R8NXVkI33quIoUJOY-2GLZWxhVdupWbNIzwqhtoalGIGowqE_cXa95Dt-ql23vgCgarfZFckQJjFuQqJcpq4jGRUjNMXe52pN2_tYtM_3Vj9CqroBFRsVXm5Zek3_IoNgr4cAgorKqDyJZY-Pck6mGnAGUE5AhNZpyeN"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEi8P9yp6PElcmmto1ib7l2hNQG9R8NXVkI33quIoUJOY-2GLZWxhVdupWbNIzwqhtoalGIGowqE_cXa95Dt-ql23vgCgarfZFckQJjFuQqJcpq4jGRUjNMXe52pN2_tYtM_3Vj9CqroBFRsVXm5Zek3_IoNgr4cAgorKqDyJZY-Pck6mGnAGUE5AhNZpyeN" width="400px"></a>
<br>Fig "Antenna representations"</p>
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<br><font class=header2>Feedback loop</font><br>
<font class=contentf><br>
UE knows <font title="Channel State Information/Indicator Reference Signal">CSI-RS</font> antenna ports and number of layers (equal to <font title="Demodulation Reference Signal">DM-RS</font> ports), but it is *not* aware of Precoding.
UE is supposed to figure out best possible beam(s) and MIMO Precoding and inform it back as <font title="Precoding Matrix Indicator">PMI</font> in CSI feedback (report).
<br><br>
Note that (for <font title="Frequency range 1 (till 6 GHz)">FR1</font>) <font title="Channel State Information/Indicator Reference Signal">CSI-RS</font> are not beamformed.
UE may apply various beamforming and MIMO Precoding from Codebook to received <font title="Channel State Information/Indicator Reference Signal">CSI-RS</font> and <font title="Demodulation Reference Signal">DM-RS</font> to figure out best possible <font title="Precoding Matrix Indicator">PMI</font> for its reception.
Just like rest of RX processing, above processing is proprietary i.e. left to the (UE) implementation).
<br><br></font>
<br><font class=header2>Next step (reading)</font><br>
<font class=contentf><br>
Next step is: understanding the Codebook from practical point of view (with conceptual background covered so far).
This is not in the scope of this article.
Please refer <a title="R1-1612661 Advanced CSI Codebook Structure" href="https://www.3gpp.org/ftp/tsg_ran/WG1_RL1/TSGR1_87/Docs/R1-1612661.zip">[7]</a> and <a title="3GPP TS 38.214 Physical layer procedures for data" href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.214/">[1]</a> (38.214:5.2.2.2) for this step.
<br><br>
For more on covered topics, please refer <a title="3G Evolution: HSPA and LTE for Mobile Broadband" href="http://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#LTE-Erik">[4]</a> (chapter 6), <a title="5G NR: The Next Generation Wireless Access Technology" href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-Dahlman">[5]</a> (chapter 11), and <a title="5G NR in bullets" href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-bullets-johnson">[6]</a> (chapters 1.21, 4.3.3, and 13.6.3).
<br><br>
Next page contain more references if you would like to explore polarisation, oversampled beams, and related Beamforming concepts.
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p1.html">1</a>
</td>
<td align=center title="Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p2.html">2</a>
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<td align=center title="Precoding for Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p3.html">3</a>
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<td align=center title="Beamforming and MIMO" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p4.html">4</a>
</td>
<td align=center title="CSI Codebook" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p5.html">5</a>
</td>
<td align=center class=pcurr>6
</td><td align=center title="References" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p7.html">7</a>
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer - 2</font><br><br>
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<font class=contentf><br>
Beamforming (that we have covered in this article) is based on high mutual correlation between the antenna elements
(distance between consecutive antenna elements is fraction of wavelength, so it gives high mutual correlation).
For multi-layer transmission, beams are chosen in such a way that there is least correlation (sufficient spatial separation) between participating beams.
MIMO Precoding is based on exactly this characteristic of low mutual correlation between the antenna ports
(in other words, different antenna ports experience different channels).
<br><br>
In result, we now have two Precoding metrices, <b>W<sub>1</sub></b> and <b>W<sub>2</sub></b>.
<b>W<sub>1</sub></b> to choose Beam or list of Beams and <b>W<sub>2</sub></b> for Beam selection and/or MIMO Precoding.
MIMO Precoding will include co-phasing between participating beams as is expected from MIMO Precoding.
<br><br>
MIMO Precoding (by its design) will require more instantaneous channel knowledge/estimates than Beamforming Precoding.
This implies that we need to have two types of Precoding update cycles.
Slower cycle for Beamforming Precoding updates and Faster cycle for MIMO Precoding updates !!
By same reasoning, <b>W<sub>1</sub></b> wiil be Wideband/frequency independent whereas <b>W<sub>2</sub></b> will be Subband/frequency selective.
<br><br></font>
<br><font class=header1>CSI Codebook</font><br>
<font class=contentf><br>
5G NR specifies four types of CSI codebooks,
<br><br>
<li>Type 1 Single Panel, </li>
<li>Type 1 Multi-Panel,</li>
<li>Type 2, and </li>
<li>Type 2 Port Selection.</li>
<br>
Type 1 are meant for <font title="Single User MIMO">SU-MIMO</font> and Type 2 are meant for <font title="Multiple User MIMO">MU-MIMO</font>.
Detailed discussions about these codebooks are *not* in the scope of this article.
We shall instead cover antenna representations, which forms the base of these codebooks.
<br><br></font>
<br><font class=header2>Antenna panels</font><br>
<font class=contentf><br>
Three representations for antenna are shown in below diagram.
Physical antenna may have multiple antenna elements, but it is logically represented as N<sub>1</sub> columns and N<sub>2</sub> rows of pairs,
each pair having two cross polarised antenna elements.
This gives us 2*N<sub>1</sub>*N<sub>2</sub> <font title="Channel State Information/Indicator Reference Signal">CSI-RS</font> ports.
<br><br>
Further, oversampling (sampling rate higher than Nyquist rate) gives us greater number of beams than possible with the given number of antenna elements.
This brings us O<sub>1</sub> and O<sub>2</sub> values as shown in the figure below.
Total number of possible beams will then be N<sub>1</sub>*O<sub>1</sub>*N<sub>2</sub>*O<sub>2</sub>.
<br><br>
Note that distance between antenna elements is half of the wavelength, as required by Beamforming.
However, there could be multiple panels and between the panels, distance could be half of the wavelength or more.
<br><br>
Basic idea is: each beam is identified by (N<sub>1</sub>,O<sub>1</sub>,N<sub>2</sub>,O<sub>2</sub>) coordinates.
So, in a way, it becomes a protocol between base station and UE.
<br><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p1.html">1</a>
</td>
<td align=center title="Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p2.html">2</a>
</td>
<td align=center title="Precoding for Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p3.html">3</a>
</td>
<td align=center title="Beamforming and MIMO" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p4.html">4</a>
</td>
<td align=center class=pcurr>5
</td><td align=center title="Feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p6.html">6</a>
</td>
<td align=center title="References" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p7.html">7</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-15601955237831379672023-12-16T18:21:00.009+05:302023-12-18T06:53:06.356+05:30wp-mimo2-p4<!-- copy FROM here -->
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer - 2</font><br><br>
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<font class=contentf><br>
We took same input <b><i>l</i></b> for all antenna elements, so, in a way,
what we achieved is, beamforming for one layer (i.e. one stream of data) with one beam.
If we want to transmit 2 layers, we can use half of the antenna elements for one layer and the remaining for second layer.
Phase shift will be same for both the beams.
So, this will work if the polarisation of the antenna elements chosen for first layer is orthogonal to the polarisation of the antenna elements chosen for second layer.
Polarisation is a directional characteristic of the antenna elements (vertical, horizontal, circular, and so on).
This is illustrated in figure below.
<br><br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgaFGhY11PRc6Og8qfjgsvc9fPlktIfBykBBQ40msbML0HhnZuA0-gwNQyApO4b6zDrc349UBSBdzklzw3bz6aL2cMjhEQxDWMoykLE4CGDiqMA-dKBtpan6qLkRLEl2Ps7rRIWLnUr-BDxoQAs-giW17UrnDRK3kxgURazN3pO8tdMAwnY5I48sr9nrm3z"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEgaFGhY11PRc6Og8qfjgsvc9fPlktIfBykBBQ40msbML0HhnZuA0-gwNQyApO4b6zDrc349UBSBdzklzw3bz6aL2cMjhEQxDWMoykLE4CGDiqMA-dKBtpan6qLkRLEl2Ps7rRIWLnUr-BDxoQAs-giW17UrnDRK3kxgURazN3pO8tdMAwnY5I48sr9nrm3z" width="400px"></a>
<br>Fig "Cross-polarised beams"</p>
</font>
<font class=contentf>
5G NR indeed uses cross-polarised antenna elements.
This means, Beamforming Precoding matrix takes the form as shown in above figure.
We may call these beams "cross-polar beams".
<br><br></font>
<br><font class=header2>Beamforming and MIMO</font><br>
<font class=contentf><br>
5G NR uses Beamforming when number of antenna ports are 4 or more (4, 8, 12, 16, 24, and 32).
Beamforming is used not only for <font title="Multiple User MIMO">MU-MIMO</font> but also for <font title="Single User MIMO">SU-MIMO</font>.
The idea in using Beamforming in SU-MIMO is to support higher number of layers.
<br><br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhXpPXBfwH0ddaqnfgbJ5sHdbG9mI3DhDL1aNcafkBZNlVU3ZTNDYwLzLyX3kylI3VhPHK4FCnl03r202a_xfVIxWqHoJagXg8bGxQtpCAptWCSZ366sKSld49XBQ2voeXoKiwCGlyCPf5tDFjCkf9Yv5WSXx9GJmjRrqa5HkV9K7XKapFnw_odObEDkPsw"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEhXpPXBfwH0ddaqnfgbJ5sHdbG9mI3DhDL1aNcafkBZNlVU3ZTNDYwLzLyX3kylI3VhPHK4FCnl03r202a_xfVIxWqHoJagXg8bGxQtpCAptWCSZ366sKSld49XBQ2voeXoKiwCGlyCPf5tDFjCkf9Yv5WSXx9GJmjRrqa5HkV9K7XKapFnw_odObEDkPsw" width="400px"></a>
<br>Fig "One UE, two beams"</p>
</font>
<font class=contentf><br>
In scenario shown in above figure, Beamforming Precoding will not be sufficient as
the reflected waves from the second beam will reach the UE bit later compared to the first beam.
This is the classic multipath-propagation scenario of MIMO.
So, in addition to Beamforming Precoding, we will need MIMO Precoding here.
<br><br>
Another way to look at it is from the point of view of correlation between antenna elements.
<br><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p1.html">1</a>
</td>
<td align=center title="Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p2.html">2</a>
</td>
<td align=center title="Precoding for Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p3.html">3</a>
</td>
<td align=center class=pcurr>4
</td><td align=center title="CSI Codebook" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p5.html">5</a>
</td>
<td align=center title="Feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p6.html">6</a>
</td>
<td align=center title="References" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p7.html">7</a>
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer - 2</font><br><br>
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<font class=contentf><br>
So, as seen, by adjusting delays between equidistant linear antenna elements,
receptions can be made favorable to certain angles or directions.
More the number of antenna elements, thinner will be the beam lobes.
<br><br>
If you notice, the concept is reciprocal.
Instead of adjusting receiver antenna element delays, we can adjust transmitting antenna element delays to achieve the same result !
<br><br>
Below is a plot of amplitude Vs <b>θ</b> in circular graph with the adjustments for 0 degree and 45 degrees.
<br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEi7zhFTPDGeQmT3ja9UexQzRNIAfkrNOzfic0piCjFj_YtisiQRt0mH5F-iphA_MjYFs7xV4Z3ZJ0DWoDwqEjJ_9OhMugOO6nQoFbjZlA24cANKOKOFLW5A-XRXS6K6VHj_KDnzgjXTNJ85CwRKrl3IIHIHS5LlkPxD7iJ_-E9V281dJi0E0_8yyRJ3JLd_"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEi7zhFTPDGeQmT3ja9UexQzRNIAfkrNOzfic0piCjFj_YtisiQRt0mH5F-iphA_MjYFs7xV4Z3ZJ0DWoDwqEjJ_9OhMugOO6nQoFbjZlA24cANKOKOFLW5A-XRXS6K6VHj_KDnzgjXTNJ85CwRKrl3IIHIHS5LlkPxD7iJ_-E9V281dJi0E0_8yyRJ3JLd_" width="400px"></a>
<br>Fig "Beam lobes (circular graph)"</p>
</font>
<font class=contentf><br>
This is the basic principle behind beamforming used by 5G NR.
For more precise and detailed treatment of the basic concept, please refer <a title="Digital Beamforming in Wireless Communications by Litva" href="https://us.artechhouse.com/Digital-Beamforming-in-Wireless-Communications-P1033.aspx">[2]</a> and <a title="Beamforming math" href="https://mathscinotes.wordpress.com/2012/01/20/beamforming-math/">[3]</a> .
<br><br></font>
<br><font class=header2>Precoding for Beamforming</font><br>
<font class=contentf><br>
If we apply Beamforming on transmitting antenna elements, equation for each antenna element will look like
(input <b><i>l</i></b> is same for all antenna elements),
<br><br>
<b>
t<sub>1</sub> = l<br>
t<sub>2</sub> = <i>e</i><sup>j.<i>π</i>.sinθ</sup>. l<br>
t<sub>3</sub> = <i>e</i><sup>j.<i>2</i>.<i>π</i>.sinθ</sup>. l<br>
...<br>
t<sub><i>k</i></sub> = <i>e</i><sup>j.(<i>k</i>-1).<i>π</i>.sinθ</sup>. l<br>
</b>
<br>
This can be put in matrix format as,
<br><br>
<b>[T] = <i>v</i> . [L]</b>
<br><br>
So, <b><i>v</i></b> is our Precoding matrix for Beamforming as below (superscript <i>T</i> is a notation for transpose of matrix),
<br><br>
<b><i>v</i> = [1 <i>e</i><sup>j.<i>π</i>.sinθ</sup> <i>e</i><sup>j.<i>2</i>.<i>π</i>.sinθ</sup> ... <i>e</i><sup>j.(<i>k</i>-1).<i>π</i>.sinθ</sup> ]<sup><i>T</i></sup></b>
<br><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p1.html">1</a>
</td>
<td align=center title="Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p2.html">2</a>
</td>
<td align=center class=pcurr>3
</td><td align=center title="Beamforming and MIMO" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p4.html">4</a>
</td>
<td align=center title="CSI Codebook" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p5.html">5</a>
</td>
<td align=center title="Feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p6.html">6</a>
</td>
<td align=center title="References" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p7.html">7</a>
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer - 2</font><br><br>
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<br><font class=header1>Beamforming</font><br>
<font class=contentf><br>
To understand Beamforming, let us take a simplified case of 4 receiver antenna elements separated by equal distance of half wavelength.
Total reception is addition of receptions from individual receiver antenna elements.
If antenna elements happen to be perpendicular to the transmitted waves, best reception is achieved as shown in figure below.
If we realign (tilt) antenna elements (as shown in figure below) by angle (<b>θ</b>),
receptions from individual antenna elements start canceling each other.
At certain value of <b>θ</b>, (theoretically) there will be zero reception.
<br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhslLZL2A1ZnO-qrIwK5hDSCLBpmvqd6xujseiGWl_PWhqCgoa8mYphY1WK9rnOzjQ24t5Y7BSmteIL8UumakmCJb5BCZdrT-taSp9-XuNuiwHwvdruH_grAPOXuMC5XStRPCKTne2f1Sz2_A3ZpyBW0C9bqrWtwdWEYlHMT_hnp5PHordKZcSM9Fr4d7UU"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEhslLZL2A1ZnO-qrIwK5hDSCLBpmvqd6xujseiGWl_PWhqCgoa8mYphY1WK9rnOzjQ24t5Y7BSmteIL8UumakmCJb5BCZdrT-taSp9-XuNuiwHwvdruH_grAPOXuMC5XStRPCKTne2f1Sz2_A3ZpyBW0C9bqrWtwdWEYlHMT_hnp5PHordKZcSM9Fr4d7UU" width="300px"></a>
<br>Fig "Antenna elements"</p>
</font>
<font class=contentf><br>
Realigning antenna elements has basically forced each antenna element to receive delayed wave
compared to its predecessor antenna element by constant value, say <b>Δ</b>t.
If you notice, <b>Δ</b>t is dependent on <b>θ</b> and can be calculated as, <b>Δ</b>t = <i>π</i> sin(<b>θ</b>).
<br><br>
If <b>r<sub><i>k</i></sub></b> is received signal at <b><i>k</i></b>th antenna element, we get
<br><br>
<b>R = <i>e</i><sup>j</sup>. r<sub>1</sub> + <i>e</i><sup>j.<i>π</i>.sinθ</sup>. r<sub>2</sub> + <i>e</i><sup>j.2.<i>π</i>.sinθ</sup>. r<sub>3</sub> + <i>e</i><sup>j.3.<i>π</i>.sinθ</sup>. r<sub>4</sub> = Σ (<i>e</i><sup>j.(<i>k</i>-1).<i>π</i>.sinθ</sup>. r<sub><i>k</i></sub>) </b>
<br><br>
If we plot amplitude Vs <b>θ</b> (-90 to +90), it will give us our famous beam lobes, as shown below (8 antenna elements).
<br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEjttGEv2KmfAsk55kVCT54kBC5vwJsX_LENldadXbSaf9KzJGcuZHIfc1javH-i5qOSDj7zNLz7UV5XtutyxWo098S0RW0eoXB7i4B_g_d77UQMs06Wc1yx-syg8fGfEzdagGn56Dtc6IMwfgSUmqd9aQ6VzIWPM3PFG2wFs3MDHz4coQoqdQWMWzKP7KKl"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEjttGEv2KmfAsk55kVCT54kBC5vwJsX_LENldadXbSaf9KzJGcuZHIfc1javH-i5qOSDj7zNLz7UV5XtutyxWo098S0RW0eoXB7i4B_g_d77UQMs06Wc1yx-syg8fGfEzdagGn56Dtc6IMwfgSUmqd9aQ6VzIWPM3PFG2wFs3MDHz4coQoqdQWMWzKP7KKl" width="200px"></a>
<br>Fig "Beam lobes"</p>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p1.html">1</a>
</td>
<td align=center class=pcurr>2
</td><td align=center title="Precoding for Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p3.html">3</a>
</td>
<td align=center title="Beamforming and MIMO" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p4.html">4</a>
</td>
<td align=center title="CSI Codebook" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p5.html">5</a>
</td>
<td align=center title="Feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p6.html">6</a>
</td>
<td align=center title="References" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p7.html">7</a>
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<font class=byf>Article</font><br>
<font class=titlef>
MIMO for 3GPP L2 RAN Developer - 2
</font><br><font class=byf>
by
</font><br><font class=authorf>
Samir Amberkar
</font><br><font class=byf>
(published on 16-Dec-2023)
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<font class=contentf><br><br>
</font>
<br><font class=header1>Introduction</font><br>
<font class=contentf><br>
As seen in earlier article, "<a href='https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p1.html'>MIMO for 3GPP L2 RAN Developer</a>",
Precoding forms the core of MIMO.
Idea is to maintain the balance between Channel and Precoding.
Receiver knows Channel the most, so the feedback from receiver to transmitter is needed, for Precoding to be most effective.
Needless to say, the feedback is to be continuous.
<br><br>
In UL MIMO, receiver is base station, which itself is in control of Precoding (Matrix) values.
So, the feedback (or step of determination of Precoding values) is internal to base station.
In DL MIMO however, we will need signaling from UE to base station to communicate the feedback.
<br><br>
Instead of information about Channel, UE communicates recommended Precoding values via a parameter called, PMI (Precoding Matrix Indicator).
<font title="Precoding Matrix Indicator">PMI</font> is basically an index to the table of Precoding Metrices.
These tables is predefined in 3GPP specification <a title="3GPP TS 38.214 Physical layer procedures for data" href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.214/">[1]</a> (38.214:5.2.2.2) and it is known as "Codebook".
<br><br>
In this article, we will talk about <font title="Multiple User MIMO">MU-MIMO</font> and understand the basics of Beamforming.
This is needed to understand the concepts behind 3GPP Codebook.
The discussion will be in the context of 5G NR Release 15 and <font title="Frequency range 1 (till 6 GHz)">FR1</font> (sub6 GHz) frequencies.
<br><br></font>
<br><font class=header1>MU-MIMO</font><br>
<font class=contentf><br>
<font title="Multiple User MIMO">MU-MIMO</font> stands for "Multi-User MIMO".
As the word suggests, <font title="Multiple User MIMO">MU-MIMO</font> allows use of same RF resources (PRBs) for multiple users (usually a pair).
<br><br>
Below diagram is a snapshot of RF allocation: UE1 is operating in <font title="Single User MIMO">SU-MIMO</font>,
UE2 is operating in <font title="Single User MIMO">SU-MIMO</font>, whereas UE3/UE4 are operating in <font title="Multiple User MIMO">MU-MIMO</font>.
<br><br>
5G NR uses Beamforming to achieve <font title="Multiple User MIMO">MU-MIMO</font> operation.
<br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhSYEQDqs22J7E2SMduoOJLmUZ3sd_l5wCmYX9ph4S8j1x8U0pTJREapy1SZfTuFoldKFel-0AbdD7dWQRdBnz_aBbztwVpc3Lrw8EKGC_Czs8HXDkaCFq4s1WuwVlKXtu03dSAkTrOMOa5XvfXkP_3oooaTot8VAEgP2YPYY1tqYGmmCv3ursNxqLEEUL6"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEhSYEQDqs22J7E2SMduoOJLmUZ3sd_l5wCmYX9ph4S8j1x8U0pTJREapy1SZfTuFoldKFel-0AbdD7dWQRdBnz_aBbztwVpc3Lrw8EKGC_Czs8HXDkaCFq4s1WuwVlKXtu03dSAkTrOMOa5XvfXkP_3oooaTot8VAEgP2YPYY1tqYGmmCv3ursNxqLEEUL6" width="300px"></a>
<br>Fig "MU-MIMO"</p>
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<td align=center class=pcurr>1
</td><td align=center title="Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p2.html">2</a>
</td>
<td align=center title="Precoding for Beamforming" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p3.html">3</a>
</td>
<td align=center title="Beamforming and MIMO" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p4.html">4</a>
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<td align=center title="CSI Codebook" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p5.html">5</a>
</td>
<td align=center title="Feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p6.html">6</a>
</td>
<td align=center title="References" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/12/wp-mimo2-p7.html">7</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-66940756919977129102023-10-26T15:23:00.019+05:302023-10-30T14:14:41.806+05:30wp-ulpc-p3<!-- copy FROM here -->
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<br><font class=headerf>Introduction to Uplink Power Control for 3GPP RAN Developer</font><br><br>
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<br><font class=header1>Closed loop power control</font><br>
<font class=contentf><br>
Below is updated equation for closed loop power control, <br><br>
<b>P<sub>UL</sub> = minimum( P<sub>max</sub> , P<sub>0</sub> + <i>f</i>(PL) + <i>f</i>(μ) + <i>f</i>(n<sub>PRB</sub>) + <i>f</i>(Δ<sub>MCS</sub>) + δ )</b>
<br><br>
where <b>δ</b> is determined by base station and informed to UE.
<b>δ</b> is known as "<font title="Transmission Power Control">TPC</font> command" and it is part of <font title="Downlink Control Information">DCI</font>.
<br><br></font>
<br><font class=header2>Power Headroom</font><br>
<font class=contentf><br>
As indicated in earlier section, all parameters of above equation are known to base station except path loss (as experienced by UE).
To determine the path loss at base station, MAC Power Headroom (PHR) reporting is used.
As the name suggests, PHR is difference between <b>P<sub>max</sub></b> and estimated UL power.
<br><br>
UE can be configured (SRB1 MAC Configuration) to send PHR at certain intervals.
By solving below equation for <b>PL</b>, base station can find out the path loss <a title="5G NR in Bullets" href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-bullets-johnson">[6]</a> and come out with adjustment (<b>δ</b> value) to maintain optimal UL <font title="Signal to Interference and Noise Ratio">SINR</font>.
<br><br>
<b>P<sub>PHR</sub> = P<sub>max</sub> - ( P<sub>0</sub> + <i>f</i>(PL) + <i>f</i>(μ) + <i>f</i>(n<sub>PRB</sub>) + <i>f</i>(Δ<sub>MCS</sub>) )</b>
<br><br>
In a way, PHR acts like a feedback loop for uplink power control.
Refer 3GPP TS 38.321 <a title="3GPP TS 38.321 MAC protocol" href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.300/">[4]</a> (sections 5.4.6 and 6.1.3.8) for more information on PHR.
<br><br></font>
<br><font class=header1>Concluding remark</font><br>
<font class=contentf><br>
With uplink power control equation, base station will have overall cell level, UE level, and slot level control over uplink power.
Scheduling logic at base station need to make use of these parameters to achieve desired uplink data rate while ensuring minimum uplink energy and interference.
<br></font>
<font class=contentf><br><br></font>
<br><font class=header1>Abbreviations</font><br>
<font class=contentf><br></font>
<font class=contentf>
<table><tr><td class="contentf" style="font-weight:bold;padding-right:20px;">
CSI-RS<br>
DCI<br>
MCS<br>
MIB<br>
PHR<br>
PL<br>
PRB<br>
RAN<br>
SINR<br>
SSB<br>
TPC<br>
UE<br>
ULPC<br>
</td><td class="contentf">Channel State Information Reference Signal<br>
Downlink Control Information<br>
Modulation and Coding Scheme<br>
Master Information Block<br>
Power HeadRoom<br>
Path Loss<br>
Physical Resource Block<br>
Radio Access Network<br>
Signal to Interference and Noise Ratio<br>
Synchronisation Signal Burst<br>
Transmission Power Control<br>
User Equipment<br>
UpLink Power Control<br>
</td></tr></table></font>
<font class=contentf><br></font>
<br><font class=header1>References</font><br>
<font class=contentf><br></font>
<font class=contentf>1. <a href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#LTE-Erik">3G Evolution: HSPA and LTE for Mobile Broadband</a><br></font>
<font class=contentf>2. <a href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-Dahlman">5G NR: The Next Generation Wireless Access Technology</a><br></font>
<font class=contentf>3. <a href="https://www.3gpp.org/ftp//Specs/archive/38_series/38.300/">3GPP TS 38.213 Physical layer procedures for control</a><br></font>
<font class=contentf>4. <a href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.300/">3GPP TS 38.321 MAC protocol</a><br></font>
<font class=contentf>5. <a href="https://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p3.html"">Scheduling or Radio Resource Selection by Samir Amberkar</a><br></font>
<font class=contentf>6. <a href="https://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-bullets-johnson">5G NR in Bullets</a><br></font>
<font class=contentf>7. <a href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.300/">3GPP TS 38.321 MAC protocol</a><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/10/wp-ulpc-p1.html">1</a>
</td>
<td align=center title="Uplink power calculations" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/10/wp-ulpc-p2.html">2</a>
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<td align=center class=pcurr>3
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<br><font class=headerf>Introduction to Uplink Power Control for 3GPP RAN Developer</font><br><br>
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<br><font class=header1>Uplink power calculations</font><br>
<font class=contentf><br>
Target of power control is to maintain <font title="Signal to Interference and Noise Ratio">SINR</font> at receiver,
so the first step in power control is to list down the parameters that affect uplink power.
<br><br>
1) Nominal power value<br>
Simply speaking, this is the value of power when the effect of other parameters is zero.
Let us call it <b>P<sub>0</sub></b>.
We will also consider limiting the power to certain value, let us call it <b>P<sub>max</sub></b>.<br><br>
2) Path loss (as covered earlier section)<br>
Let us call it <b>PL</b>. Higher the path loss, more will be the transmit power required. <br><br>
3) Bandwidth (of the allocated resources)<br>
Wider the bandwidth, more will be the power required.
Higher numerology (bigger spacing between subcarriers) will take up more bandwidth.
So, UL power will depend on numerology (<b>μ</b>) and the number of physical resource blocks (<b>n<sub>PRB</sub></b>).
<b>n<sub>PRB</sub></b> is number of resource blocks assigned to UE in a particular slot. <br><br>
4) Modulation and coding<br>
Let us call it <b>Δ<sub>MCS</sub></b>.
Higher the MCS, more are the chances of errors and/or decoding failures.
To improve the chances of successful decoding, power need to be increased.
<br><br>
If we collate all, the equation will look like,<br><br>
<b>P<sub>UL</sub> = minimum( P<sub>max</sub> , P<sub>0</sub> + <i>f</i>(PL) + <i>f</i>(μ) + <i>f</i>(n<sub>PRB</sub>) + <i>f</i>(Δ<sub>MCS</sub>) )</b>
<br><br>
Please refer 3GPP TS 38.213:7.1 <a title="3GPP TS 38.213 Physical layer procedures for control" href="https://www.3gpp.org/ftp//Specs/archive/38_series/38.300/">[3]</a> for more detailed equation.
<br><br>
<br></font>
<br><font class=header1>Open loop power control</font><br>
<font class=contentf><br>
Base station is aware of all parameters except <b>PL</b>.
If all parameters are kept same, uplink power depend on path loss.
Path loss (as experienced by UE) is not known to base station, so base station cannot find out actual power with which UE did the uplink transmission.
This type of power calculation or control is known as open loop power control.
<br><br>
In above equation,<br><br>
<b>μ</b> is part of <font title="Master Information Block">MIB</font> (cell level),<br>
<b>P<sub>max</sub></b> is part of SIB1 (cell level),<br>
<b>P<sub>0</sub></b> is part of RRC (DRB) Configuration (UE/RRC level), and<br>
<b>n<sub>PRB</sub></b> and <b>MCS</b> are part of <font title="Downlink Control Information">DCI</font> (slot/UE level).
<br><br>
That leaves out <b>PL</b>.
UE need to estimate the path loss.
A simple way of determining path loss is to calculate difference between received power and expected power of the downlink reference signal.
Reference signal could be <font title="Synchronisation Signal Burst">SSB</font> or <font title="Channel State Information Reference Signal">CSI-RS</font>.
<br><br>
Open loop power control ensures that UE adjusts the uplink power to suit the transmission and compensates the path loss.
This however may not guarantee that UL <font title="Signal to Interference and Noise Ratio">SINR</font> at base station is at intended value at all times.
If there is a way for base station to adjust/tune uplink power, base station will have more control over UL <font title="Signal to Interference and Noise Ratio">SINR</font>.
Closed loop power control allows base station to do the same.
<br><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/10/wp-ulpc-p1.html">1</a>
</td>
<td align=center class=pcurr>2
</td><td align=center title="Closed loop power control" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/10/wp-ulpc-p3.html">3</a>
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<font class=byf>Article</font><br>
<font class=titlef>
Introduction to Uplink Power Control for 3GPP RAN Developer
</font><br><font class=byf>
by
</font><br><font class=authorf>
Samir Amberkar
</font><br><font class=byf>
(published on 26-Oct-2023)
</font></p>
<font class=contentf><br><br>
</font>
<br><font class=header1>Introduction</font><br>
<font class=contentf><br>
Though important, uplink power control is often ignored and less understood topic.
In this article, we shall make an attempt to understand the concepts behind uplink power control.
This will help both junior and senior <font title="Radio Access Network">RAN</font> developers.
<br><br>
Though we will use 5G NR (Rel 15) as a reference, the principals will apply equally well to LTE.
<br><br>
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<br><font class=header1>Background</font><br>
<font class=contentf><br>
Receiving the signal at optimum power (<font title="Signal to Interference and Noise Ratio">SINR</font>) is desirable for successful decoding (reception).
If we can control transmission power to maintain <font title="Signal to Interference and Noise Ratio">SINR</font> at receiver, we can maintain the desired date rate.
In a way, power control is a link adaptation technique wherein power is controlled to get the best data rate <a title="Scheduling or Radio Resource Selection by Samir Amberkar" href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p3.html"">[5]</a> .
<br><br>
During propagation, signals face gradual attenuation (loss of power due to the medium).
This is known as "path loss (PL)".
To compensate the path loss, transmission power need to be increased.
This may lead to increased interference/noise to other transmissions.
Ensuring that the interference/noise is within certain limits is also a consideration behind power control.
<br><br>
<font title="User Equipment">UE</font> is power limited, so we need to ensure its power efficiency.
Though this is not a prime factor, it is of importance in designing power control techniques/protocols.
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<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEjhqBRUuokRDMYg690Ds8KdfE_jhYM9K_uDM5HJ0ZNCW9nplPtg65eK3OVJ-RWBIwtJAwuDLiVJLQB1un5Gs1sn8MrCq3l1RT4HCxIr5T5b75VKAQpUVFCjkh-5Usx8KgK6kL3m78msvcKIoucfmHStZ04YyXJUznd3TVanpjkzn0-r2ahySXkN5vfBZrz4"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEjhqBRUuokRDMYg690Ds8KdfE_jhYM9K_uDM5HJ0ZNCW9nplPtg65eK3OVJ-RWBIwtJAwuDLiVJLQB1un5Gs1sn8MrCq3l1RT4HCxIr5T5b75VKAQpUVFCjkh-5Usx8KgK6kL3m78msvcKIoucfmHStZ04YyXJUznd3TVanpjkzn0-r2ahySXkN5vfBZrz4" width="400px"></a>
<br>Fig "ULPC"</p>
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<td align=center class=pcurr>1
</td><td align=center title="Uplink power calculations" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/10/wp-ulpc-p2.html">2</a>
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<td align=center title="Closed loop power control" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/10/wp-ulpc-p3.html">3</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-76648042106852405372023-06-10T11:35:00.004+05:302023-11-06T09:19:04.570+05:30wp-mimo-p6<!-- copy FROM here -->
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer</font><br><br>
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<br><font class=header2>MIMO Signaling</font><br>
<font class=contentf><br>
MIMO based DL and UL allocations use DCI formats 1_1 and 0_1 respectively.
<font title="Channel State Information">CSI</font> reports include MIMO (feedback) related parameters.
More about MIMO feedback in later articles.
<br><br>
This completes initial understanding of MIMO, needed to understand 3GPP 5G NR specifications.
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<font class=contentf><br><br></font>
<br><font class=header1>Abbreviations</font><br>
<font class=contentf><br></font>
<font class=contentf>
<table><tr><td class="contentf" style="font-weight:bold;padding-right:20px;">
CSI<br>
CSI-RS<br>
DMRS<br>
MCS<br>
MIMO<br>
SRS<br>
TTI<br>
</td><td class="contentf">Channel State Information<br>
Channel State Information/Indicator Reference Signal<br>
Demodulation Reference Signal<br>
Modulation and Coding Scheme<br>
Multiple Input Multiple Output<br>
Sounding Reference Signal<br>
Time to Transmit Interval<br>
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<br><font class=header1>References</font><br>
<font class=contentf><br></font>
<font class=contentf>1. <a href="http://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#LTE-Erik">3G Evolution: HSPA and LTE for Mobile Broadband</a><br></font>
<font class=contentf>2. <a href="http://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#5G-Dahlman">5G NR: The Next Generation Wireless Access Technology</a><br></font>
<font class=contentf>3. <a href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.300/">3GPP TS 38.300 NR and NG-RAN Overall Description</a><br></font>
<font class=contentf>4. <a href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.212/">3GPP TS 38.212 Multiplexing and channel coding</a><br></font>
<font class=contentf>5. <a href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.214/">3GPP TS 38.214 Physical layer procedures for data</a><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p1.html">1</a>
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<td align=center title="Precoding" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p2.html">2</a>
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<td align=center title="Layer mapping" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p3.html">3</a>
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<td align=center title="5G NR" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p4.html">4</a>
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<td align=center title="MIMO feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p5.html">5</a>
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<td align=center class=pcurr>6
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer</font><br><br>
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<br><font class=header2>MIMO feedback loop</font><br>
<font class=contentf><br>
As mentioned in section "Channel Sounding"(<a href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p2.html">page 2</a>), receiver need a feedback about channel (<b>[c]</b>).
In 3GPP, base station control both DL and UL configurations, so the feedback is needed only for DL transmissions.
This is especially true in FDD, where DL carrier frequency is different than UL carrier frequency.
In TDD, base station may decide DL configurations based on UL measurements, assuming channel (experienced) in DL and UL is same.
<br><br>
In DL, base station uses <font title="Channel State Information">CSI</font> feedback to determine next DL configuration.
CSI feedback is part of Scheduler's PHY signaling.
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<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhemhM26rwj7GxEAk_S3GmW-zryPWcWvf3eqBcWcvr67MfYXXowLvqmS2i3CbJySWmEgVvF5kLvxukhVoOrFh5ZIoMoWJCb2HK2FNETzz9N8vJbOZaNTKz0QUCTy2_dQ_UmvOPYkg3XeVY9i1g2QVR2Usakty3E6wjycNqM3qcNUrDLRaKm3Fx3RUnfig"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEhemhM26rwj7GxEAk_S3GmW-zryPWcWvf3eqBcWcvr67MfYXXowLvqmS2i3CbJySWmEgVvF5kLvxukhVoOrFh5ZIoMoWJCb2HK2FNETzz9N8vJbOZaNTKz0QUCTy2_dQ_UmvOPYkg3XeVY9i1g2QVR2Usakty3E6wjycNqM3qcNUrDLRaKm3Fx3RUnfig" width="300px"></a>
<br>Fig "DL MIMO feedback loop"</p>
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<font class=contentf><br>
In UL, feedback signaling is not needed; base station determines next UL configuration based on its own SRS based measurements.
<br><br></font>
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<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEiUlgSFzLnvxep73Q6FsL3DHLZa-f6gaAuZs_co1MTDlhyq7Z6HtGXL3svEB6gDN_jfxMoi_TnPt19sgcK3J6eAJ8bwXqQRz3VRG-tZLAWZHm-FteLEqaibE19y7cqI99Bwin_4rM9-7cQkUPPVtrZYbeWGN-3RGVPT2tq92uCBMHvvG8YO8UXUSdA7oQ"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEiUlgSFzLnvxep73Q6FsL3DHLZa-f6gaAuZs_co1MTDlhyq7Z6HtGXL3svEB6gDN_jfxMoi_TnPt19sgcK3J6eAJ8bwXqQRz3VRG-tZLAWZHm-FteLEqaibE19y7cqI99Bwin_4rM9-7cQkUPPVtrZYbeWGN-3RGVPT2tq92uCBMHvvG8YO8UXUSdA7oQ" width="300px"></a>
<br>Fig "UL MIMO feedback loop"</p>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p1.html">1</a>
</td>
<td align=center title="Precoding" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p2.html">2</a>
</td>
<td align=center title="Layer mapping" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p3.html">3</a>
</td>
<td align=center title="5G NR" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p4.html">4</a>
</td>
<td align=center class=pcurr>5
</td><td align=center title="MIMO Signaling" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p6.html">6</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-45392953984309580572023-06-10T11:33:00.005+05:302023-11-02T07:02:06.300+05:30wp-mimo-p4<!-- copy FROM here -->
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer</font><br><br>
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<br><font class=header2>5G NR</font><br>
<font class=contentf><br>
5G NR supports two codewords.<br><br>
In the context of 5G NR,<br>
<i><b>d</b></i> is <font title="Demodulation Reference Signal">DMRS</font> , "Demodulation Reference Signal",<br>
In DL, <i><b>s</b></i> is <font title="Channel State Information/Indicator Reference Signal">CSI-RS</font> - "Channel State Information/Indicator Reference Signal"<br>
<br><br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhQFtRMvRb4RnNosgxTMW44dhHNmXRYETVNBD37JSlMWMa8Z6wS9w7045Gg8iiMpgHa2NeUgxQ_ZR_un-MD9dxJw-xk1lyKXh6ux1c_g8RQ99ci4ratGwr2Rl8R9bYIomScfCaRMfZM-XYil9rrDvc2nhiFwNPHlq_UefNe8QIeSb2hAKae2dYtRFeGIVSO"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEhQFtRMvRb4RnNosgxTMW44dhHNmXRYETVNBD37JSlMWMa8Z6wS9w7045Gg8iiMpgHa2NeUgxQ_ZR_un-MD9dxJw-xk1lyKXh6ux1c_g8RQ99ci4ratGwr2Rl8R9bYIomScfCaRMfZM-XYil9rrDvc2nhiFwNPHlq_UefNe8QIeSb2hAKae2dYtRFeGIVSO" width="600px"></a>
<br>Fig "DL MIMO"</p>
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<font class=contentf><br>
In UL, <i><b>s</b></i> is <font title="Sounding Reference Signal">SRS</font> - "Sounding Reference Signal".<br><br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgtmUkLTcdgpP8XfD8CjFP3msz9iQzZBbKcZgkOYrpn9EmKUe5mbpln3KcW-tK5g6KejsKACJgWbmYmxVEXdUSbJI-_Uz4PqKvbzIdPoX831UpiwFlnbQ9XIyOuVAK4Es70yXcGJ8T5qi_PZdaJeDMCNVOaPFm4uuE0Qz3S1cPC7PlPVPt-MzQL0VitnkQY"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEgtmUkLTcdgpP8XfD8CjFP3msz9iQzZBbKcZgkOYrpn9EmKUe5mbpln3KcW-tK5g6KejsKACJgWbmYmxVEXdUSbJI-_Uz4PqKvbzIdPoX831UpiwFlnbQ9XIyOuVAK4Es70yXcGJ8T5qi_PZdaJeDMCNVOaPFm4uuE0Qz3S1cPC7PlPVPt-MzQL0VitnkQY" width="600px"></a>
<br>Fig "UL MIMO"</p>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p1.html">1</a>
</td>
<td align=center title="Precoding" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p2.html">2</a>
</td>
<td align=center title="Layer mapping" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p3.html">3</a>
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<td align=center class=pcurr>4
</td><td align=center title="MIMO feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p5.html">5</a>
</td>
<td align=center title="MIMO Signaling" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p6.html">6</a>
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<br><font class=header2>Layer mapping</font><br>
<font class=contentf><br>
As we have multiple antenna ports, the input stream of data or signal need to be "split" or "mapped" to these antenna ports before precoding.
Each mapped stream is called "a layer".
The process is called "layer mapping".
<br><br>
<font style="background:yellow;">If you notice, the number of <i><b>d</b></i> signals or antenna ports is equal to the number of layers.</font>
<br><br>
Also, as already mentioned in earlier section, the number of layers cannot be more than the number of transmit antenna ports.
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<br><font class=header2>Coding, Codeword, and Modulation</font><br>
<font class=contentf><br>
In practice, instead of stream or continuous data, processing happen on chunk of data at certain time interval (aka slot or <font title="Time to Transmit Interval">TTI</font>).
This chunk of data is known as "a codeword".
A codeword is generated after "modulating" "coded" "transport block".
<br><br>
Below figure shows above processing blocks.
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<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEg6Wn-kE3TbC7x9f8D9V-W2akEtkQ9LiA72CBNP8TR-vhC2y95TYB8S5RldlyMZbpKk-5QG72Sz9zV911Xm4ToTox1r7vJ1aS-J9cBrxKbVk19YgDwcc6Mfd-yhWaX8-19pyXWd5f-yWo5ioUcKykzgUQWhRWhnIW8m2UQmiNfqnUuke80TFX3Y60bsVw"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEg6Wn-kE3TbC7x9f8D9V-W2akEtkQ9LiA72CBNP8TR-vhC2y95TYB8S5RldlyMZbpKk-5QG72Sz9zV911Xm4ToTox1r7vJ1aS-J9cBrxKbVk19YgDwcc6Mfd-yhWaX8-19pyXWd5f-yWo5ioUcKykzgUQWhRWhnIW8m2UQmiNfqnUuke80TFX3Y60bsVw" width="500px"></a>
<br>Fig "Layer mapping"</p>
</font>
<font class=contentf><br>
Coding refer to processing of transport block data (bits) by error detection and recover algorithms.<br>
Codeword is actually modulated signal, represented as complex frequency domain values.<br><br>
Refer <a href="https://samiramberkar-tutorials.blogspot.com/2021/08/5g-1.html">this</a> article for top level view of PHY DL chain processing.
<br><br>
Based on the number of layers that we intend to transmit, size of transport block differ.
More the number of layers, bigger will be the transport block, and more will be the throughput.
Two layers will provide twice throughput (assuming <font title="Modulation and Coding Scheme">MCS</font> value remain the same).
<br><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p1.html">1</a>
</td>
<td align=center title="Precoding" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p2.html">2</a>
</td>
<td align=center class=pcurr>3
</td><td align=center title="5G NR" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p4.html">4</a>
</td>
<td align=center title="MIMO feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p5.html">5</a>
</td>
<td align=center title="MIMO Signaling" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p6.html">6</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-8201788592736500392023-06-10T11:31:00.004+05:302023-06-10T20:02:11.288+05:30wp-mimo-p2<!-- copy FROM here -->
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<br><font class=headerf>MIMO for 3GPP L2 RAN Developer</font><br><br>
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<br><font class=header2>Precoding</font><br>
<font class=contentf><br>
Putting it in matrix equation format,
<p align=center><b>[r] = [c] . [t] + [n]</b><p>
If we figure out inverse of <b>[c]</b> and apply it to the transmission (below figure), the equation will look like,
<p align=center><b>
[r] = [c] . [c]<sup>-1</sup> . [t] + [n]<br><br>
[r] = [t] + [n]<br>
</b><p></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEhw7FbyOlUQ61RfTX9SPSVqsNraPqbJySnJzopwjQtSuu5oXxWPPOvlNhf8h5yP9K0hKtzzCGzQIMyWi8V27d-z2mdlFtVoW2Q1TzoGxr5_Jaf24x1hdoROuU5L0NgmY1ObEEkEX50iZ6TQSBl2FqAPrpVBqM7knPE8tS4EC633LU3eLINA0G01UAlsIA"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEhw7FbyOlUQ61RfTX9SPSVqsNraPqbJySnJzopwjQtSuu5oXxWPPOvlNhf8h5yP9K0hKtzzCGzQIMyWi8V27d-z2mdlFtVoW2Q1TzoGxr5_Jaf24x1hdoROuU5L0NgmY1ObEEkEX50iZ6TQSBl2FqAPrpVBqM7knPE8tS4EC633LU3eLINA0G01UAlsIA" width="400px"></a>
<br>Fig "Precoding"</p>
</font>
<font class=contentf>
After removing the noise, we get back transmitted signal.
The inverse of <b>[c]</b> is called Precoding matrix.
<br><br></font>
<br><font class=header2>Channel sounding</font><br>
<font class=contentf><br>
Catch is, how to find out <b>[c]</b> and its inverse.
One way to determine Precoding matrix is to get a feedback from receiver about <b>[c]</b>.
For receiver to figure out <b>[c]</b>, it will require a (reference) signal without precoding applied.
That will be "<i><b>s</b></i>" in figure below.
<br><br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEiDCNVg5cEuK2B9gdndvo_izrv0Brjwj5thTp8rsUf-F2hyEjfXoMmdvmlr3L8vPnFUl4KiZCy7RToj6ELpVaqckCPuA2Hhp9M8BKI-cWo-tctYZp-6Cz4GoK_y_jlsbqBOqKC7R8IVj3gPngDf3pzhwLxigQhLyHqM0l4uPo7fXVtE5LRRy6ZdAcriyA"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEiDCNVg5cEuK2B9gdndvo_izrv0Brjwj5thTp8rsUf-F2hyEjfXoMmdvmlr3L8vPnFUl4KiZCy7RToj6ELpVaqckCPuA2Hhp9M8BKI-cWo-tctYZp-6Cz4GoK_y_jlsbqBOqKC7R8IVj3gPngDf3pzhwLxigQhLyHqM0l4uPo7fXVtE5LRRy6ZdAcriyA" width="600px"></a>
<br>Fig "Reference signals"</p>
</font>
<font class=contentf><br>
"<i><b>d</b></i>" is a reference signal, needed for RX processing.
As the name suggests, it is reference for transmitted signal.
Due to its purpose, it is precoded along with the signal to be transmitted.
<br><br>
<font style="background:yellow;">If you notice, the number of <i><b>s</b></i> signals or antenna ports is equal to the number of transmission antenna ports.</font>
<br><br>
Also, the number of input antenna ports (to precoding) need not be same as the number of output antenna ports; it can be same or lesser (L <= T).</font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p1.html">1</a>
</td>
<td align=center class=pcurr>2
</td><td align=center title="Layer mapping" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p3.html">3</a>
</td>
<td align=center title="5G NR" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p4.html">4</a>
</td>
<td align=center title="MIMO feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p5.html">5</a>
</td>
<td align=center title="MIMO Signaling" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p6.html">6</a>
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<font class=byf>Article</font><br>
<font class=titlef>
MIMO for 3GPP L2 RAN Developer
</font><br><font class=byf>
by
</font><br><font class=authorf>
Samir Amberkar
</font><br><font class=byf>
(published on 10-Jun-2023)
</font></p>
<font class=contentf><br><br>
</font>
<br><font class=header1>Introduction</font><br>
<font class=contentf><br>
MIMO is (almost) a baseline feature for 5G NR.
Most of the commercial UE implementations will support it.
As there is considerable amount of (mathematical) theory around the concept,
novice 3GPP protocol stack developers sometimes find it difficult to comprehend it.
This article provides simplified initial understanding of <font title="Multiple Input Multiple Output">MIMO</font> from 3GPP 5G NR point of view.
<br><br>
It is assumed that the reader has basic understanding of 3GPP LTE or 5G NR PHY procedures.
<br><br></font>
<br><font class=header1>Concepts</font><br>
<br><font class=header2>Channel</font><br>
<font class=contentf><br>
In simple terms, Channel represent signal conditions.
From theory of view, it is a mathematical representation.
<br><br></font>
<br><font class=header2>Antenna ports</font><br>
<font class=contentf><br>
Often confused with or compared with physical antennas,
Antenna port is actually a virtual or logical representation.
Signals are said to be coming from two different antenna ports when they experience two different channels (signal conditions).
In other words, when signals are transmitted over two different antenna ports, they will supposedly experience two different channels.
<br><br>
<br><br></font>
<br><font class=header1>MIMO</font><br>
<br><font class=header2>Multiple transmit and receive antennas</font><br>
<font class=contentf><br>
As the name suggests, MIMO consists of multiple transmit and multiple receive antennas -
more accurately, antenna ports.
Below is an example of MIMO system with two transmit antenna ports and two receive antenna ports.
<br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEj3G9Z7xHtloDmuaP_7Fd3PzRKTKs4Uut2s7dhWO1rb80K6GYRmg3J7RkKI4QNDpqs1JQg8j-dzeWT5vG0wB7ZzE1_Im426gRYu8-kRPn37uBtJAR2oZy_7zih6ByhM0cYPX0LDG3ijWK38p7cAozRhk8AhVC3LCp0S2wig6VFOXgGED0hHdTUwUiBbgQ"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEj3G9Z7xHtloDmuaP_7Fd3PzRKTKs4Uut2s7dhWO1rb80K6GYRmg3J7RkKI4QNDpqs1JQg8j-dzeWT5vG0wB7ZzE1_Im426gRYu8-kRPn37uBtJAR2oZy_7zih6ByhM0cYPX0LDG3ijWK38p7cAozRhk8AhVC3LCp0S2wig6VFOXgGED0hHdTUwUiBbgQ" width="400px"></a>
<br>Fig "2x2 MIMO"</p>
</font>
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<td align=center class=pcurr>1
</td><td align=center title="Precoding" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p2.html">2</a>
</td>
<td align=center title="Layer mapping" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p3.html">3</a>
</td>
<td align=center title="5G NR" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p4.html">4</a>
</td>
<td align=center title="MIMO feedback loop" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p5.html">5</a>
</td>
<td align=center title="MIMO Signaling" class=pother>
<a class=ilinkf href="https://samiramberkar-articles.blogspot.com/2023/06/wp-mimo-p6.html">6</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-85139897243130893842022-08-14T19:59:00.003+05:302022-08-14T20:27:51.870+05:30wp-scheduling-p4<!-- copy FROM here -->
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<br><font class=headerf>Scheduling or Radio Resource Selection</font><br><br>
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<br><font class=header1>Big question</font><br>
<font class=contentf><br>
That brings us to the question: we have just too many parameters/perspectives to choose from, how do we design scheduling ?
<br><br>
There may not be single one algorithm to take care of all of the above perspectives.
What we need is certain set of steps in sequence (priority order), separation of various decisions,
with some steps having proper selection strategy (like UE selection).
<br><br>
For example, we may allocate resources first for common resources (SSB, SIBs etc.),
then look at DL allocations, followed by UL allocations (or UL first and then DL).
Common resources are usually cell level configurations, so above approach may be preferable.
<br><br>
Within DL allocations, we may decide to cater only certain number UEs in a <font title="Time to Transmit Interval">TTI</font> time.
The UE selection may be <font title="Round Robin">RR</font> or Max C/I or Proportional Fair.
<br><br>
In UL allocations too, we could use similar strategy.
<br><br>
In both DL and UL allocations, control information (physical control channels) may be prioritised over UE selection.
<br><br>
Last, but not least, all scheduling algorithms are going to be highly proprietary in nature,
will require fine tuning and constant upgrade based on field cases: urban regions versus rural regions,
in developing countries versus developed countries, pico cell versus micro cell versus macro cell,
time of the day (morning time versus day time versus night time) and residential versus office areas and so on.
<br><br></font>
<font class=contentf><br><br></font>
<br><font class=header1>Abbreviations</font><br>
<font class=contentf><br></font>
<font class=contentf>
<table><tr><td class="contentf" style="font-weight:bold;padding-right:20px;">
PFS<br>
RR<br>
TTI<br>
</td><td class="contentf">Proportional Fair Scheduler<br>
Round Robin<br>
Time to Transmit Interval<br>
</td></tr></table></font>
<font class=contentf><br></font>
<br><font class=header1>References</font><br>
<font class=contentf><br></font>
<font class=contentf>1. <a href="http://samiramberkar-tutorials.blogspot.com/2010/06/reference-books-and-reviews.html#LTE-Erik">3G Evolution: HSPA and LTE for Mobile Broadband</a><br></font>
<font class=contentf>2. <a href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.300/">3GPP TS 36.300 E-UTRA and E-UTRAN overall description</a><br></font>
<font class=contentf>3. <a href="http://www.3gpp.org/ftp//Specs/archive/38_series/38.300/">3GPP TS 38.300 NR and NG-RAN Overall Description</a><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p1.html">1</a>
</td>
<td align=center title="Perspectives" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p2.html">2</a>
</td>
<td align=center title="Perspectives continued" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p3.html">3</a>
</td>
<td align=center class=pcurr>4
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-65494875393568317462022-08-14T19:58:00.003+05:302022-08-21T10:38:42.715+05:30wp-scheduling-p3
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<br><font class=headerf>Scheduling or Radio Resource Selection</font><br><br>
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<br><font class=header2>Signal conditions (channel quality)</font><br>
<font class=contentf><br>
We could adjust transmission power to maintain the error rate below threshold.
Error rate is usually measured in BLER, BLock Error Rate -
ratio of erroneous (decoding failed) transport blocks to the total number of transmitted transport blocks.
Better the signal conditions (lower BLER), lower the transmit power needed, lower will be the interference to other users and cells.
As error rate is kept in check, stable data rate is achieved.
This is one type of link adaptation.
<br><br>
Another type of link adaptation technique is to adjust MCS value. MCS stand for Modulation and Coding (redundancy) Scheme.
Better the signal conditions (channel quality), higher will be the MCS chosen (higher order modulation and lesser redundancies).
In a way, data rate keep changing and it follow channel quality.
This process is also known as "Adaptive MCS".
<br><br>
Adaptive MCS is usually preferred method over power control.
<br><br>
Adaptive MCS would always end up selecting only those UEs which have best channel quality among available UEs for selection.
This type of selection is called "Max C/I".
<br><br>
If we always select UEs with best channel quality, cell would always operate at best capacity.
However QoS may not get honoured for all UEs and/or some UEs may get starved.
<br><br>
Channel quality also vary over frequencies (apparent in wide band or higher bandwidth cases).
When allocating RBs, we may want to take this into consideration to get maximum cell capacity.
<br><br>
<font title="Round Robin">RR</font> selection may not be most efficient whereas Max C/I may not be most fair.
There is an algorithm called "Proportional Fair Scheduling" (PFS) which bridge the gap between <font title="Round Robin">RR</font> and Max C/I.
It tries to select UEs which has best channel quality and has not reached its needed average data rate.
This ensure that the UEs with better channel quality reach needed average data rate faster.
At the same time, as best channel UEs are not scheduled again and again, less likelihood that UEs will be starved.
Selection of time period is critical here, smaller than optimum value will make it look like Max C/I and
longer than optimum will push it near to <font title="Round Robin">RR</font> performance.
<br><br></font>
<br><font class=header2>User traffic profile</font><br>
<font class=contentf><br>
Before an algorithm is chosen for scheduling, it is imperative to profile the user traffic.
If user traffic is bursty in nature with similar average data rates of all users,
even RR scheduling will work well with very good cell level data rates.
<br><br>
However, in practice, user traffic is not known or it keeps changing based on the time of the day or
it simply is changing due to various unpredictable unknown reasons.
So type of traffic is usually not considered in design, rather it is assumed that the user traffic
will compromise of both constant bit rate and bursty bearers.
<br><br></font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p1.html">1</a>
</td>
<td align=center title="Perspectives" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p2.html">2</a>
</td>
<td align=center class=pcurr>3
</td><td align=center title="Big question" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p4.html">4</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-4490990011191902022022-08-14T19:56:00.003+05:302022-08-14T19:56:41.760+05:30wp-scheduling-p2<!-- copy FROM here -->
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<!-- 14-Aug-2022/Sun 19:45:53 -->
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<td align=left valign=top>
<br><font class=headerf>Scheduling or Radio Resource Selection</font><br><br>
</td>
<td class=pfmtsf></td></tr>
<tr><td class=pfmtsf><div class=pfmtsfdiv3></div></td>
<td align=left valign=top>
<br><font class=header2>Common resources and Dedicated resources</font><br>
<font class=contentf><br>
Some resources are for common use e.g. synchronisation signals, PBCH(MIB), System information,
RACH message(preamble), RAR message, DL/UL allocation information, cell specific reference signals,
so on.
Some resources are for dedicated use e.g. UE dedicated allocations to carry SRB/DRB loads
(including HARQ retransmissions), signalling (scheduling requests, power control, timing adjustments,
HARQ acknowledgements), UE specific reference signals, DL CSI measurement reporting, so on.
<br><br></font>
<br><font class=header2>Physical/MAC layer related control information and transport block or codeword*</font><br>
<font class=contentf><br>
Transport block is basically data along with PDCP/RLC/MAC headers.
After FEC coding (Phy/DSP function) of a transport block , we get a codeword.
PDCCH, PUCCH, PRACH, Synchronisation signals, and Reference signals (both common and UE specific) would
fall under control information.
PDSCH and PUSCH would hold codeword.
<br><br></font>
<br><font class=header2>Resource separation</font><br>
<font class=contentf><br>
We already mentioned that at each <font title="Time to Transmit Interval">TTI</font>, scheduler need to decide resource allocation.
This automatically brings time separation between resources.
Also, we may choose different RBs or resource elements for different allocations, indicating frequency separation.
However, with techniques like CDMA, Multi-user diversity (pre-coding based MU-MIMO),
and beam forming , it is possible to have multiple allocations in same frequency and time region.
This effectively increase the amount of resources for allocations.
<br><br>
<br>
Below perspectives mainly cover selection criteria (that could be used by scheduling algorithm).
<br><br></font>
<br><font class=header2>UE selection</font><br>
<font class=contentf><br>
UE selection require selection of DL/UL resource either for DL/UL signalling (including reference signals)
and/or for transfer of DL/UL transport block or codeword.
Question here is: how to select a UE - in round robin fashion, random order, based on its age in the queue,
based on its buffer volume, or based on some other non-radio parameters.
Idea is to not to let starve or ignore any UE.
<br><br>
<font title="Round Robin">RR</font> method is of course the simplest algorithm.
It possibly most fair, but not necessarily most efficient.
Users, even with poor conditions or smaller payloads get to use the resources,
but do not add much to system capacity
(assuming only certain number of UEs are processed in a <font title="Time to Transmit Interval">TTI</font> time).
<br><br></font>
<br><font class=header2>Bearer QoS/QCI</font><br>
<font class=contentf><br>
Each bearer type (SRB or DRB or Common bearer) and their allocated QoS parameters are to be honoured during selection process.
<br><br></font>
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<font class=footerf>
Copyright © Samir Amberkar
</font>
</td><td width=50% align=right>
<font class=footerf>
Page 2 of 4
</font>
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<td align=center title="Introduction" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p1.html">1</a>
</td>
<td align=center class=pcurr>2
</td><td align=center title="Perspectives continued" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p3.html">3</a>
</td>
<td align=center title="Big question" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p4.html">4</a>
</td>
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<!-- TILL here -->Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-32171233928335252932022-08-14T17:15:00.003+05:302022-08-14T19:55:05.070+05:30wp-scheduling-p1<!-- copy FROM here -->
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<br><font class=headerf> </font><br><br>
</td>
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<td class=pfmtsf><div class=pfmtsfdiv3></div></td>
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<p align=center>
<font class=byf>Article</font><br>
<font class=titlef>
Scheduling or Radio Resource Selection
</font><br><font class=byf>
by
</font><br><font class=authorf>
Samir Amberkar
</font><br><font class=byf>
(published on 14-Aug-2022)
</font></p>
<br><font class=header1>Introduction</font><br>
<font class=contentf><br>
The discussion is generic and may apply well to both LTE and 5G NR base stations.
At every <font title="Time to Transmit Interval">TTI</font> time, MAC scheduler has the responsibility
to choose radio resources for various purposes.
Radio resources mean all resource elements, available in one <font title="Time to Transmit Interval">TTI</font> time across all resource blocks.
A <font title="Time to Transmit Interval">TTI</font> time could further be seen as multiple symbols and a resource block could further
be seen as multiple sub-carriers.
A <font title="Time to Transmit Interval">TTI</font> time is typically one slot time for 5G NR and one subframe time for LTE.
<br><br></font>
<font class=contentf>
<p style="text-align:center"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEivRU4zEPDBJb-XLcuvuFkE855p4VqD7mpdkr0jabdH_M4t0XNmePK-nuR9_HufxeU4H0UhR9VliFn56cjcF9CMCyca0Zi0gxSzAmNCYmHtODrHM6BF8gp_ikeiO3WYQ1Ites77jjFiqP4_MwMLc8E-QKEM6nn0Q8WmdLaVFuFEMSImDP431zibWCZFJQ"><img alt="click to view better" class="imgs" src="https://blogger.googleusercontent.com/img/a/AVvXsEivRU4zEPDBJb-XLcuvuFkE855p4VqD7mpdkr0jabdH_M4t0XNmePK-nuR9_HufxeU4H0UhR9VliFn56cjcF9CMCyca0Zi0gxSzAmNCYmHtODrHM6BF8gp_ikeiO3WYQ1Ites77jjFiqP4_MwMLc8E-QKEM6nn0Q8WmdLaVFuFEMSImDP431zibWCZFJQ" width="230px"></a>
<br>Fig "Resource grid"</p>
</font>
<br><font class=header1>Perspectives</font><br>
<font class=contentf><br>
If we talk about resource, there are various perspectives here.
<br><br></font>
<br><font class=header2>DL and UL</font><br>
<font class=contentf><br>
UL allocation happen via DL signalling. So, there is inherent relation between DL and UL resources.
Additionally, in TDD, UL measurements may be used for deciding DL allocations.
The same is not true for FDD; in FDD, we may need explicit DL measurements (by UE).
<br><br></font>
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<font class=footerf>
Copyright © Samir Amberkar
</font>
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<font class=footerf>
Page 1 of 4
</font>
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</table>
</td>
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</td></tr>
<tr><td><br>
<table><tr>
<td align=center class=pcurr>1
</td><td align=center title="Perspectives" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p2.html">2</a>
</td>
<td align=center title="Perspectives continued" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p3.html">3</a>
</td>
<td align=center title="Big question" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2022/08/wp-scheduling-p4.html">4</a>
</td>
</td></tr></table>
</td></tr>
</table>
</body>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-34577386771022485502022-04-27T09:39:00.008+05:302022-04-27T14:57:24.851+05:30Search-Music-Album<script>
var vinyl_search = 0;
function gselectall() {
checkBoxAll = document.getElementById("check_all");
checkBox = document.getElementById("check_musiccircle.co.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_vinylworld.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_therevolverclub.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_123sold.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_ngh.co.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_bollywoodvinyl.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_onlinevinylshop.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_mossymart.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_vinyakmusic.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_banumass.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_bidcurious.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_indiamusicstore.co.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_rghindia.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_audiolounge.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_art365.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_lakshmimusicshop.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_recordsindia.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_avdigital.in");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_blisstainment.com");;checkBox.checked = checkBoxAll.checked;
checkBox = document.getElementById("check_discogs.com");;checkBox.checked = checkBoxAll.checked;
}
function gsubmit() {
var checkBox;
var site_present = 0;
document.getElementById('q').value = document.getElementById('qdummy').value;
document.getElementById('qdummy').value = '';
if(vinyl_search) {
document.getElementById('q').value += ' vinyl';
}
checkBox = document.getElementById("check_musiccircle.co.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:musiccircle.co.in'; }
checkBox = document.getElementById("check_vinylworld.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:vinylworld.in'; }
checkBox = document.getElementById("check_therevolverclub.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:therevolverclub.com'; }
checkBox = document.getElementById("check_123sold.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:123sold.in'; }
checkBox = document.getElementById("check_ngh.co.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:ngh.co.in'; }
checkBox = document.getElementById("check_bollywoodvinyl.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:bollywoodvinyl.in'; }
checkBox = document.getElementById("check_onlinevinylshop.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:onlinevinylshop.com'; }
checkBox = document.getElementById("check_mossymart.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:mossymart.com'; }
checkBox = document.getElementById("check_vinyakmusic.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:vinyakmusic.com'; }
checkBox = document.getElementById("check_banumass.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:banumass.com'; }
checkBox = document.getElementById("check_bidcurious.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:bidcurious.com'; }
checkBox = document.getElementById("check_indiamusicstore.co.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:indiamusicstore.co.in'; }
checkBox = document.getElementById("check_rghindia.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:rghindia.com'; }
checkBox = document.getElementById("check_audiolounge.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:audiolounge.in'; }
checkBox = document.getElementById("check_art365.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:art365.in'; }
checkBox = document.getElementById("check_lakshmimusicshop.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:lakshmimusicshop.com'; }
checkBox = document.getElementById("check_recordsindia.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:recordsindia.com'; }
checkBox = document.getElementById("check_avdigital.in");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:avdigital.in'; }
checkBox = document.getElementById("check_blisstainment.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:blisstainment.com'; }
checkBox = document.getElementById("check_discogs.com");if(checkBox.checked == true){ if(site_present) { document.getElementById('q').value += ' OR'; } else { site_present = 1; } document.getElementById('q').value += ' site:discogs.com'; }
}
function gsubmit2() {
vinyl_search = 1;
}
</script>
<style>
.vinyltextbox4 {
border-width:1px;
border-style:solid;
border-color:black;
background-color:white;
font-family:Georgia;
color: black;
width:100px;
}
.vinylbutton3 {
border-width:1px;
border-style:solid;
border-color:black;
background-color:#f0f0f0;
font-family:Georgia;
color: black;
}
.vinylcheckbox {
border-width:1px;
border-style:solid;
border-color:black;
color: black;
}
.vinylfont {
font-family:Georgia;
color: black;
}
</style>
<body class=bodystyle>
<table class=twidth>
<tr>
<td valign=top>
<table width=100%><tr>
<td class=pline>
<table width=100%>
<tr><td class=pfmtsf><!--<div class=pfmtsfdiv3></div>--></td>
<td align=center valign=top>
<font class='vinylfont'>
<br><table align=center>
<tr>
<td colspan=3 align=center>
<b>Search Music Albums</b><br>
(Vinyl records, Audio CDs, and so on).<br><br>
<form action='https://www.google.com/search' method='get' name='dummy' onsubmit='gsubmit();return true;'>
<input class='vinyltextbox4' id='qdummy' name='qdummy'/>
<input class='vinyltextbox4' type='hidden' id='q' name='q'/>
<input class='vinylbutton3' type='submit' value='Search Album'/>
<input class='vinylbutton3' type='submit' value='Search Vinyl'/ onclick='gsubmit2();return true;'>
<br><br>
</td>
</tr>
<tr>
<td><input class='vinylcheckbox' type="checkbox" id="check_all" onclick="gselectall();"><i>Select all</i><br><br>
</td><td><input class='vinylcheckbox' type="checkbox" checked id="check_musiccircle.co.in">musiccircle.co.in<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" checked id="check_vinylworld.in">vinylworld.in<br><br>
</td></tr><tr><td><input class='vinylcheckbox' type="checkbox" id="check_therevolverclub.com">therevolverclub.com<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_123sold.in">123sold.in<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_ngh.co.in">ngh.co.in<br><br>
</td></tr><tr><td><input class='vinylcheckbox' type="checkbox" id="check_bollywoodvinyl.in">bollywoodvinyl.in<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_onlinevinylshop.com">onlinevinylshop.com<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_mossymart.com">mossymart.com<br><br>
</td></tr><tr><td><input class='vinylcheckbox' type="checkbox" id="check_vinyakmusic.com">vinyakmusic.com<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_banumass.com">banumass.com<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_bidcurious.com">bidcurious.com<br><br>
</td></tr><tr><td><input class='vinylcheckbox' type="checkbox" id="check_indiamusicstore.co.in">indiamusicstore.co.in<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_rghindia.com">rghindia.com<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_audiolounge.in">audiolounge.in<br><br>
</td></tr><tr><td><input class='vinylcheckbox' type="checkbox" id="check_art365.in">art365.in<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_lakshmimusicshop.com">lakshmimusicshop.com<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_recordsindia.com">recordsindia.com<br><br>
</td></tr><tr><td><input class='vinylcheckbox' type="checkbox" id="check_avdigital.in">avdigital.in<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_blisstainment.com">blisstainment.com<br><br>
</td><td><input class='vinylcheckbox' type="checkbox" id="check_discogs.com">discogs.com<br><br>
</td></tr>
<tr>
<td colspan=3 align=center>
<br>
<font class=footerf>
Copyright © Samir Amberkar
</font>
</td></tr>
</table>
</form>
</font>
</td>
<td class=pfmtsf></td></tr>
<tr><td colspan=2><br><!--<br><br>--></td></tr>
</table>
</td>
</tr></table>
</td></tr>
</table>
</body>
Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-24668712351702264432021-02-08T10:25:00.019+05:302021-04-07T09:26:49.266+05:30wp-understanding-catm1-p7<!-- copy FROM here -->
<!-- Post title: wp-understanding-catm1-p7 -->
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<!-- 07-Apr-2021/Wed 09:24:16 -->
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<td align=left valign=top>
<br><font class=headerf>Understanding LTE Cat M1 (eMTC)</font><br><br>
</td>
<td class=pfmtsf></td></tr>
<tr><td class=pfmtsf><div class=pfmtsfdiv3></div></td>
<td align=left valign=top>
<br><font class=header1>Summary</font><br>
<font class=contentf><br>
eMTC may be an easier way to cater to IoT devices by having Small cells (Femto) with eMTC functionality.
The article has provided sufficient information for LTE RAN/UE developers to get core understanding of eMTC.
Please go through documents mentioned in References below for more information and details.
<br><br>
You may also refer FAPI document <a title="FAPI and nFAPI specification" href="https://scf.io/en/documents/082_-_nFAPI_and_FAPI_specifications.php">[12]</a> (Rel 13/eMTC specific portions) to get insight into implementation of these enhancements from PHY point of view.</font>
<font class=contentf><br><br></font>
<br><font class=header1>Abbreviations</font><br>
<font class=contentf><br></font>
<font class=contentf>
<table><tr><td class="contentf" style="font-weight:bold;padding-right:20px;">
BR<br>
CE<br>
DCI<br>
DSP<br>
EPDCCH<br>
FFS<br>
HD-FDD<br>
IoT<br>
M2M<br>
MAC<br>
MIB<br>
MPDCCH<br>
MTC<br>
NB<br>
NB-IoT<br>
PBCH<br>
PDCCH<br>
PDSCH<br>
PHY<br>
PRB<br>
PSS<br>
PUCCH<br>
PUSCH<br>
RAR<br>
RF<br>
RRC<br>
SIB<br>
SSS<br>
TBS<br>
eMTC<br>
</td><td class="contentf">Bandwidth Reduced<br>
Coverage Enhancement<br>
Downlink Control Information<br>
Digital Signal Processor<br>
Enhanced Physical Downlink Control CHannel<br>
For Future Study<br>
Half Duplex Frequency Division Duplexing<br>
Internet Of Things<br>
Machine To Machine<br>
Medium Access Control<br>
Master Information Block<br>
MTC Physical Downlink Control CHannel<br>
Machine Type Communication<br>
NarrowBand<br>
NarrowBand IoT<br>
Physical Broadcast CHannel<br>
Physical Downlink Control CHannel<br>
Physical Downlink Shared CHannel<br>
PHYsical layer<br>
Physical Resource Block<br>
Primary Synchronisation Signal<br>
Physical Uplink Control CHannel<br>
Physical Uplink Shared CHannel<br>
Random Access Response<br>
Radio Frequecy<br>
Radio Resource Control<br>
System Information Block<br>
Secondary Synchronisation Signal<br>
Transport Block Size<br>
LTE enhancements for Machine Type Communication<br>
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<font class=contentf><br></font>
<br><font class=header1>References</font><br>
<font class=contentf><br></font>
<font class=contentf>1. <a href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.888/">3GPP TR 36.888 Study on provision of low-cost MTC UEs based on LTE</a><br></font>
<font class=contentf>2. <a href="https://www.3gpp.org/ftp/Information/WORK_PLAN/Description_Releases/">3GPP release descriptions</a><br></font>
<font class=contentf>3. <a href="https://www.3gpp.org/news-events/3gpp-news/1805-iot_r14">3GPP Standards for the IoT</a><br></font>
<font class=contentf>4. <a href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.300/">3GPP TS 36.300 Rel-13 E-UTRAN Overall </a><br></font>
<font class=contentf>5. <a href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.331/">3GPP TS 36.331 Rel-13 RRC</a><br></font>
<font class=contentf>6. <a href="http://samiramberkar-articles.blogspot.com/2012/06/wp-lte-allocations-explained-p0.html">LTE Allocations explained</a><br></font>
<font class=contentf>7. <a href="http://samiramberkar-articles.blogspot.com/2012/08/wp-lte-allocations-explained-2-p1.html">LTE Allocations explained - 2</a><br></font>
<font class=contentf>8. <a href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.211/">3GPP TS 36.211 Rel-13 PHY channels</a><br></font>
<font class=contentf>9. <a href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.213/">3GPP TS 36.213 Rel-13 PHY procedures</a><br></font>
<font class=contentf>10. <a href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.212/">3GPP TS 36.212 Rel-13 PHY channel coding</a><br></font>
<font class=contentf>11. <a href="http://samiramberkar-tutorials.blogspot.com/2011/01/lte-0.html">LTE tutorials and articles</a><br></font>
<font class=contentf>12. <a href="https://scf.io/en/documents/082_-_nFAPI_and_FAPI_specifications.php">FAPI and nFAPI specification</a><br></font>
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Copyright © Samir Amberkar
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<td align=center title="Background and Introduction" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p1.html">1</a>
</td>
<td align=center title="Category 0 UE" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p2.html">2</a>
</td>
<td align=center title="Table 1: Narrowbands" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p3.html">3</a>
</td>
<td align=center title="Cross-subframe scheduling" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p4.html">4</a>
</td>
<td align=center title="EPDCCH and MPDCCH" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p5.html">5</a>
</td>
<td align=center title="Putting it together" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p6.html">6</a>
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<td align=center class=pcurr>7
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-91921399004439135812021-02-08T10:25:00.018+05:302021-04-07T09:26:18.547+05:30wp-understanding-catm1-p5<!-- copy FROM here -->
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<br><font class=headerf>Understanding LTE Cat M1 (eMTC)</font><br><br>
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<br><font class=header1>EPDCCH and MPDCCH</font><br>
<font class=contentf><br>
In simplified terms, EPDCCH use certain number of PRBs (not necessarily consecutive) - from PDSCH portion - for transmission of downlink and uplink allocation information.
EPDCCH stand for "Enhanced Physical Downlink Control CHannel".
MPDCCH is based on EPDCCH.
MPDCCH stand for "MTC Physical Downlink Control CHannel".
<br><br>
Refer below sections <a title="3GPP TS 36.211 Rel-13 PHY channels" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.211/">[8]</a> for more detailed information about EPDCCH and MPDCCH.<br><br>
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36.211:6.2.4A
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Enhanced Resource-Element Groups (EREGs)
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36.211:6.8A.1
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EPDCCH formats
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36.211:6.8B.1
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MPDCCH formats
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36.213: 9.1.4.4
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PRB-pair indication for EPDCCH
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<br>
MPDCCH may also be <b>repeated</b> in <b>consecutive</b> subframes in same or different (frequency hopping) narrowband.
Same is the case with PDSCH.
There is always one subframe gap between last of the MPDCCH repetitions and first PDSCH.
MPDCCH repetition information is known beforehand whereas PDSCH repetition information is captured in <font title="Downlink Control Information">DCI</font> sent in MPDCCH.
<br><br>
MPDCCH carry control information related downlink and uplink allocation; three new <font title="Downlink Control Information">DCI</font> formats have been introduced for eMTC UEs.
Format 6-1 is meant for DL allocation, format 6.0 for UL allocation, and format 6.2 for Paging.
Refer 36.212:5.3.3.1 <a title="3GPP TS 36.212 Rel-13 PHY channel coding" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.212/">[10]</a> for more details.
<br><br></font>
<br><font class=header1>MPDCCH monitoring</font><br>
<font class=contentf><br>
eMTC UE monitor MPDCCH candidates depending on its state and procedure.
Let us take an example of RACH.
<br><br>
eMTC SIB2 PRACH configuration provide details about MPDCCH like narrowband, repetition, and so on.
After sending RACH preamble, eMTC UE monitor the MPDCCH narrowband for <font title="Random Access Response">RAR</font>(MSG2).
eMTC SIB2 also provide information of RACH preambles - this is how eMTC UEs are distinguished from LTE UEs.
<br><br>
Let us look at MPDCCH in bit more detail from monitoring point of view.
<br><br>
36.36.213:9.1.5 <a title="3GPP TS 36.213 Rel-13 PHY procedures" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.213/">[9]</a> "MPDCCH assignment procedure" define four types of search spaces.
A search space is set of resources that UE attempt to receive and decode.
Resource is virtual representation of physical resources.
<br><br>
In case of MPDCCH, resource is an ECCE.
An ECCE is consists of multiple enhanced resource element groups (EREGs).
Physical resource block pair contain 16 EREGs.
A physical resource block pair is basically two slots in one subframe.
To simplify it for understanding, you may visualise one narrowband as pool of ECCEs.
<br><br>
A MPDCCH candidate is certain number of ECCEs.
So a MPDCCH search space shall contain one or more MPDCCH candidates - depending on aggregation levels - in a narrowband.
Higher aggregation levels take up more resources and result in lesser number of candidates.
Depending on type of MPDCCH search space, eMTC UE (RF function) receive ECCEs and (DSP function) attempt to decode MPDCCH candidates for all possible aggregation levels.
<br><br>
EPDCCH has concept of EPDCCH-PRB-set. An EPDCCH-PRB-set contain 2, 4, or 8 PRBs (not necessarily consecutive).
MPDCCH support 2, 4, or 2+4 PRBs in a set from 6 PRBs of a narrowband.
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Copyright © Samir Amberkar
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<td align=center title="Background and Introduction" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p1.html">1</a>
</td>
<td align=center title="Category 0 UE" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p2.html">2</a>
</td>
<td align=center title="Table 1: Narrowbands" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p3.html">3</a>
</td>
<td align=center title="Cross-subframe scheduling" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p4.html">4</a>
</td>
<td align=center class=pcurr>5
</td><td align=center title="Putting it together" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p6.html">6</a>
</td>
<td align=center title="Summary" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p7.html">7</a>
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Samir Amberkarhttp://www.blogger.com/profile/15901785524489970947noreply@blogger.comtag:blogger.com,1999:blog-567547809319557115.post-135497024563578712021-02-08T10:25:00.016+05:302021-02-08T11:33:52.331+05:30wp-understanding-catm1-p6<!-- copy FROM here -->
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<br><font class=headerf>Understanding LTE Cat M1 (eMTC)</font><br><br>
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Below are types of MPDCCH search spaces:<br><br>
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Type-2 common search space
</td><td class="contentf">
RACH procedure, RAR/MSG4 allocations
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UE-specific search space
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DL/UL allocations in connected mode
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Type-1 common search space
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Paging procedure, Paging message allocation
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Type-0 common search space
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<i><font title="For Future Study">FFS</font></i>
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<br>
MPDCCH narrowband for common search spaces is noted in eMTC SIB2.
MPDCCH narrowband for UE specific search space is part of EPDCCH/MPDCCH configuration in RRC Connection Setup message.
<br><br>
Refer 36.36.213:9.1.5 <a title="3GPP TS 36.213 Rel-13 PHY procedures" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.213/">[9]</a> for more details on MPDCCH search spaces and assignment.
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<br><font class=header1>Putting it together</font><br>
<br><font class=header2>eMTC UE point of view</font><br>
<font class=contentf><br>
In principle, eMTC UE follow same - RRC/MAC/PHY - procedures as LTE UE with certain differences.
These differences bring in low complexity, effectively leading to low cost, low power consumption devices.
<br><br>
After acquisition on eMTC SIBs, eMTC UE start RACH procedure with eMTC RACH preambles.
Further DL/UL allocations happen via MPDCCH/PDSCH procedures.
<br><br></font>
<br><font class=header2>eNB point of view</font><br>
<font class=contentf><br>
Higher the cell bandwidth, higher the number of narrowbands, higher the number of eMTC UEs that can be allocated in a subframe.
However, this has to be weighed against allocations for LTE UEs.
<br><br>
Cross-subframe scheduling and HD-FDD operation of eMTC makes resource scheduling at eNB tricky
if it has to service both LTE and eMTC UEs.
<br><br></font>
<br><font class=header1>Channel repetitions</font><br>
<font class=contentf><br>
Similar to HARQ retransmissions, repetitions improves the coverage.
Repetitions are supported for all types of information - System (MIB, SIB1-BR), Control (MPDCCH, <font title="Physical Uplink Control CHannel">PUCCH</font>), and Data (PDSCH, <font title="Physical Uplink Shared CHannel">PUSCH</font>).
<br><br>
MPDCCH repetitions can be controlled separately based on search space.
PDSCH and PUSCH repetition information is contained in DCI transmitted over MPDCCH.
<br><br>
<table>
<tr><td class="contentf" style="padding-right:20px;">
MIB (<font title="Physical Broadcast CHannel">PBCH</font>)
</td><td class="contentf">
36.211:6.6 <a title="3GPP TS 36.211 Rel-13 PHY channels" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.211/">[8]</a>
</td></tr>
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SIB1-BR
</td><td class="contentf">
36.211:6.4.1 <a title="3GPP TS 36.211 Rel-13 PHY channels" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.211/">[8]</a>
</td></tr>
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MPDCCH
</td><td class="contentf">
36.213:9.1.5 <a title="3GPP TS 36.213 Rel-13 PHY procedures" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.213/">[9]</a>
</td></tr>
<tr><td class="contentf" style="padding-right:20px;">
PUCCH
</td><td class="contentf">
36.213:10.1 <a title="3GPP TS 36.213 Rel-13 PHY procedures" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.213/">[9]</a>
</td></tr>
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PDSCH
</td><td class="contentf">
36.213:7.1.11 <a title="3GPP TS 36.213 Rel-13 PHY procedures" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.213/">[9]</a>
</td></tr>
<tr><td class="contentf" style="padding-right:20px;">
PUSCH
</td><td class="contentf">
36.213:8.0 <a title="3GPP TS 36.213 Rel-13 PHY procedures" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.213/">[9]</a>
</td></tr>
</table>
<br>
Refer 36.212:5.3.3.1 <a title="3GPP TS 36.212 Rel-13 PHY channel coding" href="http://www.3gpp.org/ftp//Specs/archive/36_series/36.212/">[10]</a> for more details on DCI formats - 6.1 (for DL), 6.0 (for UL), and 6.2 (for Paging).
<br><br>
As repetitions reduce the capacity of the cell, it may have to be minimally used based on field requirements and field trials.
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<td align=center title="Background and Introduction" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p1.html">1</a>
</td>
<td align=center title="Category 0 UE" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p2.html">2</a>
</td>
<td align=center title="Table 1: Narrowbands" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p3.html">3</a>
</td>
<td align=center title="Cross-subframe scheduling" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p4.html">4</a>
</td>
<td align=center title="EPDCCH and MPDCCH" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p5.html">5</a>
</td>
<td align=center class=pcurr>6
</td><td align=center title="Summary" class=pother>
<a class=ilinkf href="http://samiramberkar-articles.blogspot.com/2021/02/wp-understanding-catm1-p7.html">7</a>
</td>
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