Bugzilla – Full Text Bug Listing
|Summary:||A UE should not synchronize with an eNB if its RSRP is lower than -140 dBm|
|Product:||ns-3||Reporter:||Zoraze Ali <zorazeali>|
|Component:||lte||Assignee:||Biljana Bojović <bbojovic>|
Description Zoraze Ali 2018-11-30 13:19:09 EST
Created attachment 3235 [details] Example script Hi, I noticed that a UE synchronizes with the eNB, i.e., read MIB and SIB1 messages even if its RSRP is below the minimum RSRP level (-140 dBm). I think it is unnecessary to synchronize with a cell whose RSRP is below -140dBm. This is also in line with the S-criterion (qRxLevMeas - qRxLevMin > 0) condition in LteUeRrc::EvaluateCellForSelection (), where qRxLevMeas is the RSRP of the cell and qRxLevMin is the minimum RSRP required to camp on a cell. As per table 9.1.4-1 in 3GPP TS36133 the minimum RSRP level which a UE can report is -140 dBm. I am attaching a sample script to support my point. The scenario consists of one eNB and one UE, which is placed at 20000 m away from the eNB. One could see that the UE RRC state transitions from: IDLE_CELL_SEARCH to IDLE_WAIT_MIB_SIB1, and then to IDLE_WAIT_SIB1 and then from: IDLE_WAIT_SIB1 to IDLE_CELL_SEARCH because of the cell RSRP level, which fails to fulfill the S-criterion (qRxLevMeas - qRxLevMin > 0) in LteUeRrc::EvaluateCellForSelection (). I propose that a UE should only synchronize with a cell if its RSRP is greater than -140 dBm. Kind regards, Zoraze
Comment 2 Zoraze Ali 2018-11-30 13:25:56 EST
Created attachment 3237 [details] Patch Attached is the patch inline with my proposal.
Comment 3 Zoraze Ali 2018-11-30 13:29:33 EST
After applying the patch the UE RRC state will stay in IDLE_CELL_SEARCH until the RSRP of the cell is greater than -140 dBm.