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4G LTE

3GPP TS 36.213

LTE CQI Calculator

Bidirectional mapping between Signal-to-Interference-plus-noise Ratio (SINR) and Channel Quality Indicator (CQI) indices for LTE and 5G NR.

References: 3GPP TS 36.213 Section 7.2.3 Table 7.2.3-1 (CQI Definition), TS 36.101 (SINR requirements)

SINR to CQI Calculator

Enter SINR value or CQI index for bidirectional lookup

SINR (dB)

Range: -10 to 30 dB

CQI Lookup

Direct CQI lookup

Report Mode

CQI reporting mode

Actions

SINR Slider

-10 dB0 dB10 dB20 dB30 dB

SINR/CQI Quality Scale

CQI 11

Out of RangePoorFairGoodVery GoodExcellent

SINR 15.0 dB → CQI 11

CQI Index: 11

64QAM

Input SINR:15.0 dB

Report Mode:wideband

Modulation:64QAM

Code Rate:567/1024 = 0.5537

Spectral Efficiency:3.3223 bits/symbol

Recommended MCS:MCS 20

Expected BLER:10%

Quality: Very Good

Very good channel quality - Excellent throughput, suitable for 4K video and high-speed downloads

Estimated Throughput (20 MHz, SISO):

Peak (theoretical):55.81 Mbps

Realistic (with overhead):39.07 Mbps

Assumes 100 PRBs, 12 subcarriers/PRB, 14 symbols/subframe. Overhead includes control channels and reference signals.

Suitable Use Cases:

4K video streaming
High-speed downloads
Cloud gaming
Large file transfers

Excellent Conditions
64QAM modulation indicates very good SINR and low interference. Typically achieved near cell center with optimal RF conditions.

LTE CQI Reference Table

Complete CQI table (0-15) with SINR thresholds and modulation schemes

CQI	Modulation	Code Rate × 1024	Code Rate	Efficiency	SINR Range (dB)	MCS	BLER
0	N/A	-	-	0.0000	Out of range	-	100%
1	QPSK	78	0.0762	0.1523	-6.7 to -4.7	0	10%
2	QPSK	120	0.1172	0.2344	-4.7 to -2.3	0	10%
3	QPSK	193	0.1885	0.3770	-2.3 to 0.2	2	10%
4	QPSK	308	0.3008	0.6016	0.2 to 2.4	4	10%
5	QPSK	449	0.4385	0.8770	2.4 to 4.3	6	10%
6	QPSK	602	0.5879	1.1758	4.3 to 5.9	8	10%
7	16QAM	378	0.3691	1.4766	5.9 to 8.1	11	10%
8	16QAM	490	0.4785	1.9141	8.1 to 10.3	13	10%
9	16QAM	616	0.6016	2.4063	10.3 to 11.7	15	10%
10	64QAM	466	0.4551	2.7305	11.7 to 14.1	18	10%
11	64QAM	567	0.5537	3.3223	14.1 to 16.3	20	10%
12	64QAM	666	0.6504	3.9023	16.3 to 18.7	22	10%
13	64QAM	772	0.7539	4.5234	18.7 to 21.0	24	10%
14	64QAM	873	0.8525	5.1152	21.0 to 22.7	26	10%
15	64QAM	948	0.9258	5.5547	≥ 22.7	28	10%

About CQI

What is CQI?

Channel Quality Indicator (CQI) is a measurement reported by the UE to inform the eNodeB about the downlink channel quality. The eNodeB uses CQI to select the appropriate modulation and coding scheme (MCS) for optimal throughput.

CQI Reporting:

Wideband CQI: Single CQI value for entire system bandwidth
Subband CQI: Different CQI per subband (frequency selective)
Reporting Modes: Periodic or Aperiodic (triggered by eNodeB)
Update Rate: Typically 5-10 ms for periodic reports

CQI Index Meaning:

0: Out of range - no transmission recommended
1-6: QPSK modulation - poor to moderate signal
7-9: 16QAM modulation - good signal
10-15: 64QAM modulation - excellent signal

Link Adaptation

Process:

UE measures downlink channel quality (RSRP, RSRQ, SINR)
UE calculates appropriate CQI based on measurements
UE reports CQI to eNodeB via PUCCH or PUSCH
eNodeB selects MCS based on reported CQI
eNodeB schedules downlink transmission with selected MCS

SINR to CQI Mapping:

Typical SINR thresholds for modulation schemes:

< -6.7 dB: No transmission (CQI 0)
-6.7 to 5.9 dB: QPSK (CQI 1-6)
5.9 to 11.7 dB: 16QAM (CQI 7-9)
> 11.7 dB: 64QAM (CQI 10-15)

CQI and BLER:

CQI is selected to achieve a target Block Error Rate (BLER) of ~10% on the first transmission, allowing HARQ retransmissions to correct errors.