On Mon, Nov 25, 2013 at 08:24:27AM +0100, Andreas Eversberg wrote:
generally there is always a re-send due to delay between pcu and the radio interface. if all rlc/mac data blocks of an llc frame have been sent to the phone, a packet downlink ack control block is requested and scheduled. the pcu repeats all unacknowledged data blocks in a loop until it receives that requested control block. this way the pcu starts re-sending data blocks that might got lost, before it actually knows if and which blocks still need to be resend. (this procedure is described in TS 04.60.)
Are you referring to 9.1.3.1 "Acknowledge state array V(B) for GPRS TBF Mode"?
" If there are no further RLC data blocks available for transmission (i.e. the RLC data block with BSN= V(S) does not exist), the sending side shall transmit the oldest RLC data block whose corresponding element in V(B) has the value PENDING_ACK, then the next oldest block whose corresponding element in V(B) has the value PENDING_ACK, etc. "
With statistics in place it appears that for CS4 close to 50% of the sent RLC blocks are re-sends. Is that what you expected when implementing it?
holger