What are the conditions when CQI =0 is reporting in LTE?

Question

How the CQI reporting period and the DL throughput are related?

The lower CQI reporting period, the better link adaptation, so better Modulation and Coding Scheme (MCS) assignment and higher throughput?

If this is true, the best option should be to set CQI-PMI-ConfigIndex to lower values, am I right?

CQI-PMI = Channel Quality Indicator - PreCoding-matrix-Indicator.

Answer 1

Hi,

CQI zero is mainly for out of range indication, I think CQI 0 will not be reported , If L1 passing CQI zero to L2 then we can take decision like UE is out of coverage.

Answer 2

From TS 36.213 section 7.2.3 ====>>>>

"Based on an unrestricted observation interval in time unless specified otherwise in this sub clause, and an unrestricted
observation interval in frequency, the UE shall derive for each CQI value reported in uplink subframe n the highest CQI
index between 1 and 15 [ CQI table ]<< in Table 7.2.3-1 or Table 7.2.3-2 >> which satisfies the following condition, or CQI index 0 if CQI index 1 does not satisfy the condition:
- A single PDSCH transport block with a combination of modulation scheme and transport block size
corresponding to the CQI index, and occupying a group of downlink physical resource blocks termed the CSI
reference resource, could be received with a transport block error probability not exceeding 0.1. "

UE will report CQI 0 if CQI 1 won't meet the criteria.and it performs this check before reporting any CQI value.