Q for Experts: PDSCH in CSI-RS TRS tracking slots multiplexing, I see MCS of PDSCH drops to 9-10 even at very good coverage, In other PDSCH slots I see 25-26 Mcs but in TRS slots it drops a lot. Any 3gpp reference that could explain that drop or it is completely RAN vendor design?
Thanks in advance.
The UE may skip decoding a transport block in an initial transmission if the effective channel code rate is higher than
0.95, where the effective channel code rate is defined as the number of downlink information bits (including CRC bits)
divided by the number of physical channel bits on PDSCH.
3GPP 38.214 section 5.1.3
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3GPP reference is correct. Many Thanks @O.B
But i dont agree on the statement,
“The UE may skip decoding a transport block in an initial transmission if the effective channel code rate is higher than0.95, where the effective channel code rate is defined as the number of downlink information bits (including CRC bits)divided by the number of physical channel bits on PDSCH.”
0.95 is MCS 28 Target code rate R/1024, quite high ,
In our case gnb sends DCI and purposely sends lower code rate and UE follows and selects the TBS accordingly.
@LordGm
The target code rate is different that the effective code rate
When there are resource elements used by other than PDSCH in PRBs, the effective code rate goes higher and therefore MCS has to be lowered to achieve the target code rate or at least acceptable code rate.
This concept exists in LTE as well in the PRBs including PBCH or PSS/SSS. Also in LTE, MCS 28 cannot be used if PDCCH symbols > 1 for same reason
From Initial transmission does it mean before RRC connection is established, will UE be able to decode coding rate: 0.95 after RRC connected state, please clarify.