This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/baseband-devel@lists.osmocom.org/.
Dieter Spaar spaar at mirider.augusta.deHello Andreas, On Mon, 29 Mar 2010 13:39:21 +0200, "Andreas.Eversberg" <Andreas.Eversberg at versatel.de> wrote: > > from the specs it is quite clear that every access burst has different > random number when resending. but how does the network know if the burst > is from the same phone but retransmitted? in case of poor uplink many > bursts may be resent. will the network allocate a channel for every > burst received and waits for timeout? (if this is the case, emergency > calls could quickly 'evacuate' the cell.) It does not even need a poor uplink. I experience this behaviour for example with OpenBSC and the nanoBTS. If the "Immediate Assignment" is not sent fast enough, a retransmitted RACH burst will allocate another channel (the timeout for releasing an unused channel is around 2 to 5 seconds in "real" GSM networks). The maximum number of the retransmitted RACH burst is controlled by a parameter in the SYSTEM INFORMATION messages (there are several parameters which control the RACH transmission behaviour). Of course a "bad phone" can ignore those parameters and a DoS attack with continuous RACH bursts works quite well because the BTS or network does not know from which phone the burst come from. Best regards, Dieter -- Dieter Spaar, Germany spaar at mirider.augusta.de