On Sat, Jan 25, 2014 at 12:39:39PM +0100, Sipos Csaba wrote:
Hi again,
So there is only GPRS support at the moment, no EDGE. Do you guys have a plan for EDGE? To be clear I am not demanding anything, just kindly asking :-)
The answer is complicated. The current PCU code is not really good and we at sysmocom are the only ones changing that. I am keeping a TODO in the osmo-pcu code and post status reports to the PCU mailinglist from time[1] to time.
The current agenda is: * Re-factor code so it can be unit-tested and write tests * Optimize bandwidth usage * Dynamic CS mode switch
After this we will support EDGE (in a non-mixed mode config). The structure will not change that much when EDGE is added. The window handling is more dynamic (dl/ul size can be dynamically decided), more codec schemes, new CSN1 messages.
Can someone enlighten me about the current limitations of the GPRS stack?
Please have a look here[2].
For example: what are the slot configuration (or GPRS class) limitations? I am not interested in voice calls so my plan is to configure one (or maybe more than one) TRX with just PDCH channels to gain as much PD bandwidth as much as possible.
Can I use more than one downlink or uplink channels if my terminal is capable of doing that?
The current allocator can assign multiple downlink slots. It will assign only a single uplink though. The bad part is that the same uplink slot will be assigned for all phones. The more phones you have the more problems you will get. E.g. to ACK the TCP frame all phones compete for the same uplink resource.. while all other PDCHs have no uplink usage...
It is just one example of the problem space one has to deal with in GPRS/EDGE PCU.
cheers holger
[1] http://lists.osmocom.org/pipermail/osmocom-pcu/2014-January/thread.html [2] http://openbsc.osmocom.org/trac/wiki/osmo-pcu#Status