Signal to interference plus noise ratio and CQI

SINR is the ratio of the received signal level and the sum of interference and noise. The 3GPP specification does not include the SINR parameter. UE (user equipment) does not send the results back to the network. SINR is measured and used only in UE. It is used to better express the ralitionship between radio conditions and throughput. For example it can be used for calculating CQI value. Specific implementations may vary and it is up to the manufacturer to decide, how to implement this measurement. This is making difficult to compare results of different devices. SINR is also measured in LTE and 5G NR.

CQI (Channel Quality Indication) is also used in 3G and LTE. Instead of expressing the CQI as a received signal quality, the CQI expressed as a data rate that terminal can support under the actual radio conditions. Instead of SINR (which is used for calculating CQI) is CQI reported to NodeB via HS-DPCCH (Uplink High-speed Dedicated Physical Control Channel). According to CQI is determined TRFC (Transport Block Size, number of HS-PDSCH channels and modulation). CQI can be increased if the BLER value is under 10%.

SINR+CQI calculation


SINR and CQI mapping table (Category 16)

SINR [dB] CQI code Transport Block Size [B] Number of HS-PDSCH Modulation Type
-3.5 1 - - -
-2.6 2 237 1 QPSK
-1.5 3 237 1 QPSK
-0.3 4 237 1 QPSK
0.5 5 237 1 QPSK
1.7 6 237 2 QPSK
2.5 7 650 2 QPSK
3.5 8 650 2 QPSK
4.4 9 1262 3 QPSK
5.5 10 1262 3 QPSK
6.5 11 1262 3 QPSK
7.5 12 2279 4 QPSK
8.5 13 2279 4 QPSK
9.5 14 3319 5 QPSK
10.7 15 3565 5 16-QAM
11.5 16 3565 5 16-QAM
12.6 17 3565 5 16-QAM
13.4 18 3565 5 16-QAM
14.7 19 3565 5 16-QAM
15.7 20 3565 5 16-QAM
16.6 21 3565 5 16-QAM
17.5 22 9719 7 16-QAM
18.6 23 11418 8 16-QAM
19.6 24 14411 10 16-QAM
20.6 25 17237 12 16-QAM
21.4 26 21754 15 16-QAM
22.6 27 21754 15 16-QAM
23.5 28 21754 15 16-QAM
24.0 29 21754 15 16-QAM
24.8 30 25558 15 16-QAM
CQI
Ilustration of TRFC assignment

SINR mapping is created by simulating BLER.

Source: FURHT, Borivoje a Syed AHSON. HSDPA/HSUPA handbook

Source: ETSI CQI tables

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