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HH HH
UL data at PDCP-RLC buffer
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No current TB
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No current UL allocation/transmission
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BSR triggered [36.321:5.4.5,5.4.4]
MAC makes a scheduling request to PHY
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PHY sends SR (UCI 1, PUCCH) →
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PHY listening on PDCCH ςς
receives UL allocation (DCI 0, PDCCH) ←
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MAC informs "transmission opportunity" to RLC.
Pending SRs = 0.
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RLC prepares its PDU(s)
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MAC prepares transport block with BSR control element, cancels BSR, starts retxBSR timer.
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PHY sends TB (PUSCH) →
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PHY listening on PDCCH ςς
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case a)
retxBSR expires.
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If there is data to be sent, BSR would be triggered, MAC would make a scheduling request to PHY
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PHY sends SR (UCI 1, PUCCH) →
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case b)
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PHY receives UL allocation (DCI 0, PDCCH) ←
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MAC restarts retxBSR timer and informs transmission opportunity to RLC
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RLC prepares PDUs
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BSR may be triggered
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MAC prepares transport block - if BSR is pending, BSR control element would be included outgoing TB, BSR would be cancelled and retxBSR timer would be started.
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PHY sends TB (PUSCH) →
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