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laforge, 06/25/2016 02:46 PM
Ericsson RBS2000 GPRS¶
This page collects some information regarding Ericsson RBS2000 GPRS support.
The fundamental difference between what we do so far (PCU co-located with BTS) and this architecture is that the PCU is co-located with the BSC!
In order to have (E)GPRS support using RBS2000, we need to solve the following parts:- configuration / activation of timeslots using OML2000 / RSL?
- ensuring that GPRS related SI, particularly SI13 are broadcast via BCCH
- implementation of PCU TRAU frame format and converter between osmo-pcu PHY interface and them
- 16k sub-slot and 64k slot formats
- associated PCU SYNC protocol
- all various coding schemes
- paging coordination between BSC and PCU
PDCH timeslot configuration¶
It seems that in OM2000 all TCH (/F, /H, PDCH) are configued with a Combination "8", and no differentiation is made
The actual activation of the channel is expected via RSL. So it's analogous to a RSL CHAN ACT for TCH/H or TCH/F, but we also do this for a PDCH. In order to do so, we send a RSL CHAN ACT with Channel Number 0b11000 + the timeslot number. Deactivation works the same way.
GPRS RACH requests¶
The BSC must identify the GPRS RACH requests (similar to osmo-bts currently) and pass them into the PCU. This could be done using the same pcu socket interface that already exists.
GPRS paging¶
Thre's a RSL "Packet Paging Indication IE" (IEI = 0xF3) that the BSC can include when sending a paging request to the BTS. It's currently not clear what this is used for and why it is required.
TRAU frames¶
Updated by laforge almost 8 years ago · 2 revisions