As I travel I find it interesting to look at how operators configure their networks. I travel to Greece quite often and have noticed that for quite some time now, Vodafone Greece do not use CELL_FACH or CELL/URA_PCH on their network.
This is illustrated in the log extract above. A PS Radio Bearer is established with no subsequent data transfer. After 20s of inactivity the RRC Connection is released and the UE returns to IDLE. So essentially the RRC state machine that Vodafone Greece use consists of two states only. CELL_DCH and IDLE. This is quite strange as there are a number of advantages in using CELL_FACH and CELL/URA_PCH. Obviously for small amounts of data (keep alive messages etc) CELL_FACH can be used without consuming dedicated resources. When there is no data transfer, CELL_PCH or URA_PCH can be used where no radio resources are consumed, the UE can go into DRX and at the same time allow for a fast transition (i.e. low latency) back to CELL_DCH if data transfer is required.
I find it hard to think of a reason why someone would configure their network this way, as it seems very signalling intensive and high latency. Unfortunately my test device did not support Fast Dormancy rel8 so I could not see how the RNC would react if the UE indicated it had no further data to transfer.
Is there any tool which you have used to generate these logs ?
ReplyDeleteThere are a few tools on the market but they are are all commercial (TEMS, Nemo, QXDM). At the same time you also need a handset that will output diagnostic information.
ReplyDeleteInteresting... tell us about Greece!!!
ReplyDeleteDear radio access blogger,
ReplyDeleteI just studied a little about CPC (Continuous Packet Connectivity), as a way to keep phone connected all time (in Cell DCH) while at same time using DRX techniques to reduce battery waste. This reduces even further (compared to R8 Fast Dormancy) the ammount of signalling and the "reconnection" setup time when data transmission is needed again. Maybe this network would be configured as such?