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OsmoPCU » History » Revision 6

Revision 5 (daniel, 02/19/2016 10:48 PM) → Revision 6/29 (zecke2, 02/19/2016 10:48 PM)

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 = osmo-pcu = 

 A PCU (Packet Control Unit) is one of the two GPRS elements in the BSS.    It implements the RLC and MAC layers of the GPRS 
 Um (radio) interface on the MS-facing side, as well as the Gb Interface (NS,BSSGP) on the SGSN-facing side. 

 osmo-pcu is the Osmocom implementation of this PCU functionality. 

 It implements a custom L1 interface that can be used with [wiki:OsmoBTS] (specifically its 
 [http://www.sysmocom.de/products/sysmobts sysmoBTS] back-end), and also with 
 an unofficial version of OpenBTS that is being created by Fairwaves. 

 Towards the SGSN, the BSSGP and NS protocols are implemented over UDP/IP, sometimes called "NS over IP".  
 It has been tested with [wiki:OsmoSGSN] as well as an Ericsson SGSN so far. 

 osmo-pcu is not fully stable yet, but already performing useful service for a number of users. 

 == Source Code == 

 The source code is available from git://git.osmocom.org/osmo-pcu.git 

 You can browse it online via http://cgit.osmocom.org/cgit/osmo-pcu/ 

 The branch to be used with [wiki:OsmoBTS] and sysmoBTS is the 'jolly_merge' branch. 

 == Mailing List == 

 There is a mailing list for (development) discussion regarding the PCU: osmocom-pcu@lists.osmocom.org. 
 You can subscribe to it (or manage your subscription) at http://lists.osmocom.org/cgi-bin/mailman/listinfo/osmocom-pcu 

 == Status == 
 Information about testing is available here: [wiki:GPRS-testing] 

 === Supported === 
  * GPRS CS1 to CS4 
  * single-slot and multi-slot operation on downlink 
  * only single-slot operation on uplink 

 === Shortcomings / Limitations / Restrictions === 

  * Pure GPRS PCU, no EGPRS (EDGE) functionality 
  * Timeslots have to be assigned dedicated as a PDCH, no dynamic PDCH/TCH switching 
  * No support for hand-over of any sort yet 
  * No support of processing measurement reports 
  * No timing advance loop, i.e. maximum cell radius 2-3 km 
  * No dynamic link adaption for different coding schemes 
  * No resource-dependent flow control 
  * Single slot allocator only allocates from the first available PDCH
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