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Ericsson RBS2000 GPRS » History » Version 2

laforge, 06/25/2016 02:46 PM

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h1. Ericsson RBS2000 GPRS
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This page collects some information regarding Ericsson RBS2000 GPRS support.
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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!
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In order to have (E)GPRS support using RBS2000, we need to solve the following parts:
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* configuration / activation of timeslots using OML2000 / RSL?
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* ensuring that GPRS related SI, particularly SI13 are broadcast via BCCH
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* implementation of PCU TRAU frame format and converter between osmo-pcu PHY interface and them
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** 16k sub-slot and 64k slot formats
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** associated PCU SYNC protocol
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** all various coding schemes
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* paging coordination between BSC and PCU
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h2. PDCH timeslot configuration
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It seems that in OM2000 all TCH (/F, /H, PDCH) are configued with a Combination "8", and no differentiation is made
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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.
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h2. GPRS RACH requests
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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.
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h2. GPRS paging
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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.
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h2. TRAU frames
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