diff options
author | Pau Espin Pedrol <pespin@sysmocom.de> | 2021-04-26 19:22:54 +0200 |
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committer | Pau Espin Pedrol <pespin@sysmocom.de> | 2021-04-27 12:01:52 +0200 |
commit | f593fc5cbb547f5f2286725a2c98826ac8c472a5 (patch) | |
tree | ab2b8aefc46947c2c502e58c5e748f3e6cd86662 | |
parent | 039ee8200a8b5ed55304c4d49a7e4101f3d82102 (diff) |
doc/tbf.txt: Update and improve some information
Change-Id: I3cd643ef462637708c69895c62c488554a428571
-rw-r--r-- | doc/tbf.txt | 36 |
1 files changed, 25 insertions, 11 deletions
diff --git a/doc/tbf.txt b/doc/tbf.txt index 9d0db1ad..f5b39c53 100644 --- a/doc/tbf.txt +++ b/doc/tbf.txt @@ -117,13 +117,17 @@ Control TS: Polling: In order to poll uplink control block from MS, a special poll state and - frame number is stored at TBF. The scheduler reads that value and will not - assign uplink resource for other TBFs at that frame number. - - When there is no uplink transmission received on the block, a timeout is - indicated by layer 1 interface. There are two ways of checking timeout: - - The received frame is bad (BFI). - - The GSM indicates that the block should have been already received. + frame number is stored at PDCH UL Controller. The scheduler reads that value + and will not assign uplink resource for other TBFs at that frame number. + + On receipt of an Uplink RLCMAC block, it's the duty of each specific message + handler to release the expectancies previously stored in the PDCH UL + Controller. After the specific handler returns, the generic return path will + expire all reserved events up to the curent FN for that PDCH, eventually + calling timeout functions on TBFs and SBAs owning those reservations. Hence, + the layer 1 interface is expected to provide DATA.ind for each FN block, + containing data=0 if decoding failed, in order to keep the clock up-to-date in + upper layers. Because polling requires uplink response from MS, the polling must be performed at control TS. @@ -131,13 +135,21 @@ Polling: Data structures of TBFs and PDCHs: - There is a global structure for BTS. + There is a global structure for PCU (struct gprs_pcu the_pcu). + + A BTS is created and put into PCU's list for each PCUIF INFO_IND with a unique + bts_nr received. - The BTS structure has 8 TRX structures. + Each BTS structure has 8 TRX structures. Each TRX structure has 8 PDCH structures, one for each timeslot. - There are two linked lists of TBF instances: + Each BTS structure has a list of MS (struct GprsMs). + + Each MS can have 1 UL TBF and 1 DL TBF, and 1 TBF is always assigned to an + existing GprsMS structure. + + Each BTS also has two linked lists of TBF instances: - uplink TBFs - downlink TBFs @@ -158,4 +170,6 @@ Data structures of TBFs and PDCHs: On release of a TBF, the link to this PDCH is removed from all assigned PDCHs. The TBF is removed from the list of TBFs. The TBF is destroyed. - + GprsMs structures are kept alive for a while once they become unused, in order to + have a cache of MS related information it would otherwise need to acquire + again once it interacts with the PCU again. |