+QNWCFG: "nr5g_csi",<mcs>,<ri>,<cqi>,<pmi>
MCS (Modultion and Coding Scheme): Modulation and coding scheme of PDSCH. Range: 0–31.
RI (Rank Indicator): Idicates the effective number of data layers of PDSCH
CQI (Channel Quality Indicator): Idicates the quality of the downlink channel.
PMI (Precoding MAtrix Indicator): Indicates the index of the codebook set
MCS and PMI are refrences to a codebook index. But the codebook used is based on the current selected QAM modulation. Below are some examples from 5G Modulation and Coding Scheme | 5G MCS
How to know which table to use for the LTE and 5GNR responses of the above AT-commands
For 5G NR is the PMI reported as 28 and 896. Given that the second table is to be used, as the router modem is supposed to support 256QAM, how should i interpret these values?
Sorry for the delayed response. The responses from the AT commands AT+QNWCFG="lte_csi" and AT+QNWCFG="nr5g_csi" should be interpreted based on the 3GPP TS 27.007 standard. This standard defines the AT command set for LTE and 5G NR networks, offering guidelines for understanding parameters such as MCS, RI, CQI, and PMI. Referring to this standard ensures accurate interpretation of network configuration and performance metrics.
3GPP TS 38.214,
Chapter 5.1.3.1 covers Modulation order and target code rate determination.
if the higher layer parameter mcs-Table-ForDCIFormat1_2 given by PDSCH-Config is set to ‘qam256’, and the PDSCH is scheduled by a PDCCH with DCI format 1_2 with CRC scrambled by C-RNTI
the UE shall use I_MCS and Table 5.1.3.1-2 to determine the modulation order (Q_m) and Target code rate (R) used in the physical downlink shared channel.
My question is how to identify the ‘mcs-Table-ForDCIFormat1_2’ or any other value indicating the current modulation order?
Regrettably, I cannot specify the exact documentation table to consult for this information. However, to determine the modulation order, refer to the Modulation Coding Scheme (MCS) index provided, typically obtained through commands like ‘AT+QNWCFG=“ni5g_csi”’. Higher MCS index values generally indicate the use of higher-order modulations. The specific mapping between MCS index values and modulation types may vary based on network configurations and standards implemented.
