AMR misconfiguration or bug

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Omar Ramadan oramadan at fb.com
Sat Nov 3 02:59:39 UTC 2018


Hey Osmocom,


I am working to test hrAMR codec with osmo-bts-oc2g but it doesn't seem the correct TCH/F frame type is being activated:


<0000> ../../../osmo-bts/src/common/rsl.c:2805 (bts=0,trx=0,ts=1,pchan=TCH/F_TCH/H_PDCH as PDCH) ss=0 Rx RSL CHAN_ACTIV
<0000> ../../../osmo-bts/src/common/amr.c:105 AMR Multirate with 6 modes len=2 not possible
<0000> ../../../osmo-bts/src/common/rsl.c:1159 (bts=0,trx=0,ts=1,ss=0): chan_nr=TCH/H(0) on TS1 type=0x01 mode=SPEECH_AMR
<0006> ../../../osmo-bts/src/common/l1sap.c:1471 activating channel chan_nr=TCH/H(0) on TS1 trx=0
<0006> ../../../osmo-bts/src/osmo-bts-oc2g/oml.c:937 (bts=0,trx=0,ts=1,ss=0): lchan2lch_par tch_mode=0x41
<0006> ../../../osmo-bts/src/osmo-bts-oc2g/oml.c:1083 (bts=0,trx=0,ts=1,ss=0) MPH-ACTIVATE.req (hL2=0x000100bb, TCH/H TxDL)
<0006> ../../../osmo-bts/src/osmo-bts-oc2g/oml.c:822 (bts=0,trx=0,ts=1,ss=0) MPH-ACTIVATE.conf (TCH/H TxDL)
<0006> ../../../osmo-bts/src/osmo-bts-oc2g/oml.c:833 Error activating L1 SAPI TCH/H on TS 1: Invalid parameter
<0006> ../../../osmo-bts/src/osmo-bts-oc2g/oml.c:1109 (bts=0,trx=0,ts=1,ss=0) act failed mark broken due status: -4
<0006> ../../../osmo-bts/src/common/l1sap.c:623 activate confirm chan_nr=TCH/H(0) on TS1 trx=0
<0000> ../../../osmo-bts/src/common/rsl.c:787 (bts=0,trx=0,ts=1,ss=0): Sending Channel Activated NACK: cause = 0x25

Frame 202: 101 bytes on wire (808 bits), 101 bytes captured (808 bits) on interface 0
Linux cooked capture
Internet Protocol Version 4, Src: 10.42.0.1, Dst: 10.42.0.50
Transmission Control Protocol, Src Port: 3003, Dst Port: 51480, Seq: 90, Ack: 206, Len: 33
IPA protocol ip.access, type: RSL
Radio Signalling Link (RSL)
    0000 100. = Message discriminator: Dedicated Channel Management messages (4)
    .... ...0 = T bit: Not considered transparent by BTS
    .010 0001 = Message type: CHANnel ACTIVation (0x21)
    Channel number IE
    Activation Type IE
    Channel Mode IE
    Channel Identification IE
    BS Power IE
    MS Power IE
    Timing Advance IE
    MultiRate configuration IE
        Element identifier: MultiRate Configuration (0x36)
        Length: 2
        001. .... = Multirate speech version: Adaptive Multirate speech version 1 (1)
        ...0 .... = NSCB: Noise Suppression Control Bit: Noise Suppression can be used (default) (0)
        .... 1... = ICMI: Initial Codec Mode Indicator: The initial codec mode is defined by the Start Mode field (1)
        .... ..00 = Start Mode: 0
        0... .... = 12,2 kbit/s codec rate: is not part of the subset
        .0.. .... = 10,2 kbit/s codec rate: is not part of the subset
        ..1. .... = 7,95 kbit/s codec rate: is part of the subset
        ...1 .... = 7,40 kbit/s codec rate: is part of the subset
        .... 1... = 6,70 kbit/s codec rate: is part of the subset
        .... .1.. = 5,90 kbit/s codec rate: is part of the subset
        .... ..1. = 5,15 kbit/s codec rate: is part of the subset
        .... ...1 = 4,75 kbit/s codec rate: is part of the subset



I am trying to understand how codec negotiation is performed, and whether this is a bug or mis-configuration.

I've attached the BTS pcap and configurations that are being used.


Thanks,

Omar
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