CQI - stands for Channel Quality Indicator in mobile communications

Thread Starter

JimmyCho

Joined Aug 1, 2020
97
Hi guys,
Im wondering why I need CQI in lte? CQI is for determining channel modulation's rank ..but I have already
the SNR from my network which can calculate the channel modulation rank..so why I need at all the CQI ? how it's related to
channel scheme modulation and why I need CQI?

Any help please? thanks alot.
 

Delta Prime

Joined Nov 15, 2019
991
The CQI is a 4-bit integer and is based on the received signal-to-interference-plus-noise ratio (SINR) at the User Equipment (UE) .
CQI is sent from UE to the eNode-B (UP-link) to indicate a suitable downlink transmission data rate, i.e., (certain MCS value ).
MCS is the modulation and coding scheme that the eNB and UE agreed on.
Therefore, CQI is an indicator carrying the information on how good/bad the communication channel quality is.
In LTE networks, there are 15 different CQI values ranging from 1 to 15 and mapping between CQI and modulation scheme.
36_213_Table7_2_3_1_CQI_Table.png
 

Thread Starter

JimmyCho

Joined Aug 1, 2020
97
The CQI is a 4-bit integer and is based on the received signal-to-interference-plus-noise ratio (SINR) at the User Equipment (UE) .
CQI is sent from UE to the eNode-B (UP-link) to indicate a suitable downlink transmission data rate, i.e., (certain MCS value ).
MCS is the modulation and coding scheme that the eNB and UE agreed on.
Therefore, CQI is an indicator carrying the information on how good/bad the communication channel quality is.
In LTE networks, there are 15 different CQI values ranging from 1 to 15 and mapping between CQI and modulation scheme.
View attachment 230993
Thanks alot I understand, but we can also by SNR calculate the modulation scheme .. so why I need at all the CQI report? In other words I mean why I need CQI report versus to SNR report? appreciated !

We can by SNR value ofcourse calculate the modulation scheme and channel coding (in other words we could calculate MCS by SNR and not CQI)
 
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