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Aggressor cell is the cell with Stronger signal strength compared to Weaker cell, known as Victim cell.
Victim UEs are UEs in CRE region of (and on) victim cell, either moved there or just got handed
over from Aggressor cell.
Such UEs may even fail to acquire SIB1.
With FeICIC feature, eNB should be able to identity such UEs and provide them SIB1 through RRC dedicated signaling.
Refer 3GPP meeting results RP-121986 for more information.
Rel 11 [4] added capability of Multiple timing advances between component carriers.
This helped UL reception from multiple cells (RRHs and eNB).
Intent of CoMP feature is to improve throughput at cell edges by coordination between two cells.
It is meant for both homogenous and heterogenous networks.
Two schemes are mentioned for DL: JP (Joint Processing) and CS/CB (Coordinated Scheduling/Beamforming).
Under JP, DL data is transmitted from multiple points simultaneously.
Under CS/CB, DL data is coordinated between points, but transmission from one point at a time.
Similar schemes are mentioned for UL too.
Compared to eICIC, CoMP was found to be better with most performance improvement seen in worst case user experience.
Out of two CoMP schemes, performance gain is more in JP than in CS/CB.
Refer 36.819 [15] for more details.
Under Release 12 [5] , Requirements were formed for Small cells, 36.932 [11] .
Study (36.872 [13] ) was carried out by putting macro and small cells on same or different carrier frequencies.
These scenarios were checked and analysed from the perspective of
a) mobility (HO failures, Radio Link failures),
b) UL/DL imbalance (at small cell edges, UL can better received by small cells than by macro cells
as UE is nearer to small cell than to macro cell, but DL can better be received from
macro cell as macro cell will have higher signal strength than small cell by design),
c) signaling load due to handovers, and
d) after the application of CoMP/CA.
Based on the observations made, a solution of "Dual connectivity" was devised, tested, and results were compared.
DC was found to score better than CoMP/CA.
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