Cellular Network Infrastructure » Radio Access Network » OsmoPCU

When we indicate MS that we have Nack in receiving window(in PUAN). Nokia E52 MS doesn’t honor that and keeps sending the new RLC blocks even when it crosses its transmit window in UL. causing the reception of RLC blocks outside RLC window.

below is PCU log snippet for one such example:

encoding.cpp:676 - EGPRS URBB, len = 11, SSN = 671, ESN_CRBB = 670, SNS = 2048, WS = 64, V(Q) = 670, V(R) = 682, BOW, EOW

message = 40 24 01 1f 3e 90 00 92 f0 8d 35 3e ff c3 2b 2b 2b 2b 2b 2b 2b 2b 2b

Below is the decoded message.

EGPRS_AckNack
                    1... .... = ACKNACK:  (Union)
                    Desc
                        .000 1101  0... .... = ACKNACK Dissector length: 26
                        Desc
                            .0.. .... = FINAL_ACK_INDICATION: False
                            ..1. .... = BEGINNING_OF_WINDOW: 1
                            ...1 .... = END_OF_WINDOW: 1
                            .... 0101  0011 111. = STARTING_SEQUENCE_NUMBER: 671
                            .... ...0 = CRBB Exist: 0
                            1111 1111  110. .... = URBB_BITMAP: 2046

Other MS like LG F70 and Lenovo K4 note behaves properly for this kind of PUAN with nacked bits present in it.
further investigation needs to be done