Added description for do_SINR

doc/MAC/mac-usage.md

@@ -250,6 +250,8 @@ configuration](../RRC/rrc-usage.md) as well for SIB configuration.
 * `do_CSIRS` (default 0): flag whether to use channel-state information
   reference signal (CSI-RS)
 * `do_SRS` (default 0): flag whether to use sounding reference signal (SRS)
+* `do_SINR` (default 0): flag whether to enable CSI reporting of SSB-SINR (introduced in rel16)
+  Default setting of CSI reporting quantity is SSB-RSRP.
 * `min_rxtxtime` (default 2): minimum feedback time for UE to respond to
   transmissions (k1 and k2 in 3GPP spec)
 * `ul_prbblacklist`: PRBs that should not be used for UL scheduling. Cf with
@@ -272,6 +274,18 @@ configuration](../RRC/rrc-usage.md) as well for SIB configuration.
 - `du_sibs` (default `[]`): list of SIBs to transmit in the cell. Currently,
   SIB19 (for NTN) is supported.
 
+| DL MIMO                      |`do_CSIRS`|`do_SINR`| CSI report Quantity                               |
+| ---------------------------- | -------- | ------- | --------------------------------------------------|
+| OFF (pdsch_AntennaPorts = 1) |   0      |  0      | SSB-RSRP                                          |
+| OFF (pdsch_AntennaPorts = 1) |   0      |  1      | SSB-SINR                                          |
+| OFF (pdsch_AntennaPorts = 1) |   1      |  0      | CSI-Reference signal  RSRP                        |
+| OFF (pdsch_AntennaPorts = 1) |   1      |  1      | CSI-Reference signal  SINR (not supported yet)    |
+| ON (pdsch_AntennaPorts > 1)  |   1      |  0      | cri-RI-PMI-CQI                                    |
+
+DL-MIMO is configured using following parameters:
+`pdsch_AntennaPorts_XP` , `pdsch_AntennaPorts_N1` , `pdsch_AntennaPorts_N2`, `maxMIMO_layers`
+(see also [`RUNMODEM.md`](../RUNMODEM.md))
+
 ## ServingCellConfigCommon parameters
 
 The `gNBs` configuration section has a big structure `servingCellConfigCommon`