Cellular Network Infrastructure » Radio Access Network » OsmoBTS

During testing with another BTS (sysmoBTS), I found that GPRS service is
typically interrupted when an actively downloading phone is called.

Today, while testing dyn pdch on the ip.access nanobts, I found that while phone A
is actively downloading, phone B cannot call phone A.

At first I thought it was related to dyn pdch changes, but indeed the problem still exists
on the master branch, without dyn pdch being in use (5x TCH/F, 1x PDCH),
verified with openbsc.git 9329e6fb490960359d9b93d08585441d86f44b81 :

nitb log:

<0005> bsc_init.c:498 VTY at 127.0.0.1 4242
<001a> input/ipaccess.c:838 enabling ipaccess BSC mode
<0016> smpp_smsc.c:978 SMPP at 0.0.0.0 2775
<0005> bsc_hack.c:305 CTRL at 127.0.0.1 4249
DB: Database initialized.
DB: Database prepared.
<001a> input/ipa.c:265 accept()ed new link from 10.9.1.170 to port 3002
<001a> input/ipa.c:265 accept()ed new link from 10.9.1.170 to port 3003
<0004> bsc_init.c:287 bootstrapping RSL for BTS/TRX (0/0) on ARFCN 868 using MCC=1 MNC=868 LAC=1 CID=0 BSIC=63
<0004> abis_rsl.c:1466 (bts=0,trx=0,ts=0,ss=0) Activating ARFCN(868) SS(0) lctype SDCCH r=LOCATION_UPDATE ra=0x03 ta=0
<0004> abis_rsl.c:1202 (bts=0,trx=0,ts=0,ss=0) CHANNEL ACTIVATE ACK
<0002> gsm_04_08.c:1166 LOCATION UPDATING REQUEST: MI(TMSI)=3486192556 type=IMSI ATTACH 
<0003> bsc_api.c:647 BSC: Passing unknown 04.08 RR message type 0x60 to MSC
<0003> gsm_04_08.c:1282 MSC: Unimplemented GSM 04.08 RR msg type 0x60
<0002> gsm_04_08.c:555 IDENTITY RESPONSE: MI(IMEI)=357737059672710
<0002> gsm_04_08.c:507 -> LOCATION UPDATE ACCEPT
<0002> gsm_04_08.c:880 -> MM INFO
<0002> gsm_subscriber.c:305 Subscriber 274018000000012 ATTACHED LAC=1
<0002> gsm_04_08.c:1180 TMSI Reallocation Completed. Subscriber: 274018000000012
<0004> abis_rsl.c:619 (bts=0,trx=0,ts=0,ss=0) DEACTivate SACCH CMD
<0004> abis_rsl.c:1106 (bts=0,trx=0,ts=0,ss=0): MEAS RES for inactive channel
<0004> abis_rsl.c:1106 (bts=0,trx=0,ts=0,ss=0): MEAS RES for inactive channel
<0004> abis_rsl.c:665 (bts=0,trx=0,ts=0,ss=0) RF Channel Release CMD due error 0
<0004> abis_rsl.c:721 (bts=0,trx=0,ts=0,ss=0) RF CHANNEL RELEASE ACK
<0004> abis_rsl.c:1466 (bts=0,trx=0,ts=0,ss=0) Activating ARFCN(868) SS(0) lctype SDCCH r=LOCATION_UPDATE ra=0x0c ta=0
<0004> abis_rsl.c:1202 (bts=0,trx=0,ts=0,ss=0) CHANNEL ACTIVATE ACK
<0002> gsm_04_08.c:1166 LOCATION UPDATING REQUEST: MI(TMSI)=3454751355 type=IMSI ATTACH 
<0003> bsc_api.c:647 BSC: Passing unknown 04.08 RR message type 0x60 to MSC
<0003> gsm_04_08.c:1282 MSC: Unimplemented GSM 04.08 RR msg type 0x60
<0002> gsm_04_08.c:555 IDENTITY RESPONSE: MI(IMEI)=354716013859490
<0002> gsm_04_08.c:507 -> LOCATION UPDATE ACCEPT
<0002> gsm_04_08.c:880 -> MM INFO
<0002> gsm_subscriber.c:305 Subscriber 901990000000038 ATTACHED LAC=1
<0002> gsm_04_08.c:1180 TMSI Reallocation Completed. Subscriber: 901990000000038
<0004> abis_rsl.c:619 (bts=0,trx=0,ts=0,ss=0) DEACTivate SACCH CMD
<0004> abis_rsl.c:1106 (bts=0,trx=0,ts=0,ss=0): MEAS RES for inactive channel
<0004> abis_rsl.c:1106 (bts=0,trx=0,ts=0,ss=0): MEAS RES for inactive channel
<0004> abis_rsl.c:665 (bts=0,trx=0,ts=0,ss=0) RF Channel Release CMD due error 0
<0004> abis_rsl.c:721 (bts=0,trx=0,ts=0,ss=0) RF CHANNEL RELEASE ACK

[ phone A starts downloading, phone B tries to call but can't get through ]

<0004> abis_rsl.c:1466 (bts=0,trx=0,ts=2,ss=0) Activating ARFCN(868) SS(0) lctype TCH/F r=CALL ra=0x48 ta=0
<0004> abis_rsl.c:1202 (bts=0,trx=0,ts=2,ss=0) CHANNEL ACTIVATE ACK
<0002> gsm_04_08.c:988 <- CM SERVICE REQUEST serv_type=0x01 MI(TMSI)=3505312560
<0002> gsm_04_08_utils.c:681 -> CM SERVICE ACK
<0003> bsc_api.c:647 BSC: Passing unknown 04.08 RR message type 0x60 to MSC
<0003> gsm_04_08.c:1282 MSC: Unimplemented GSM 04.08 RR msg type 0x60
<000a> bsc_api.c:402 Sending ChanModify for speech: SPEECH_V1 on channel TCH_F
<0002> gsm_subscriber.c:175 Subscriber 274018000000012 not paged yet.
<0004> abis_rsl.c:1868 (bts=0,trx=0,ts=2,ss=0) IPAC_BIND speech_mode=0x10 RTP_PAYLOAD=3
<0004> abis_rsl.c:1221 (bts=0,trx=0,ts=2,ss=0) CHANNEL MODE MODIFY ACK
<0004> abis_rsl.c:2032 (bts=0,trx=0,ts=2,ss=0) IPAC_CRCX_ACK LOCAL_IP=10.9.1.170 LOCAL_PORT=4026 CON_ID=29 
<0007> paging.c:111 No slots available on bts nr 0
<0004> abis_rsl.c:619 (bts=0,trx=0,ts=2,ss=0) DEACTivate SACCH CMD
<0004> abis_rsl.c:2051 (bts=0,trx=0,ts=2,ss=0) IPAC_DLCX_IND 
<0004> abis_rsl.c:665 (bts=0,trx=0,ts=2,ss=0) RF Channel Release CMD due error 0
<0004> abis_rsl.c:721 (bts=0,trx=0,ts=2,ss=0) RF CHANNEL RELEASE ACK
<0007> paging.c:111 No slots available on bts nr 0

[ phone A stops downloading, phone B can now call it: ]

<0004> abis_rsl.c:1466 (bts=0,trx=0,ts=2,ss=0) Activating ARFCN(868) SS(0) lctype TCH/F r=CALL ra=0x44 ta=0
<0004> abis_rsl.c:1202 (bts=0,trx=0,ts=2,ss=0) CHANNEL ACTIVATE ACK
<0002> gsm_04_08.c:988 <- CM SERVICE REQUEST serv_type=0x01 MI(TMSI)=3505312560
<0002> gsm_04_08_utils.c:681 -> CM SERVICE ACK
<0003> bsc_api.c:647 BSC: Passing unknown 04.08 RR message type 0x60 to MSC
<0003> gsm_04_08.c:1282 MSC: Unimplemented GSM 04.08 RR msg type 0x60
<000a> bsc_api.c:402 Sending ChanModify for speech: SPEECH_V1 on channel TCH_F
<0002> gsm_subscriber.c:175 Subscriber 274018000000012 not paged yet.
<0004> abis_rsl.c:1868 (bts=0,trx=0,ts=2,ss=0) IPAC_BIND speech_mode=0x10 RTP_PAYLOAD=3
<0004> abis_rsl.c:1221 (bts=0,trx=0,ts=2,ss=0) CHANNEL MODE MODIFY ACK
<0004> abis_rsl.c:2032 (bts=0,trx=0,ts=2,ss=0) IPAC_CRCX_ACK LOCAL_IP=10.9.1.170 LOCAL_PORT=4000 CON_ID=32 
<0004> abis_rsl.c:1466 (bts=0,trx=0,ts=3,ss=0) Activating ARFCN(868) SS(0) lctype TCH/F r=PAGING ra=0x26 ta=0
<0004> abis_rsl.c:1202 (bts=0,trx=0,ts=3,ss=0) CHANNEL ACTIVATE ACK
<0003> bsc_api.c:647 BSC: Passing unknown 04.08 RR message type 0x60 to MSC
<0003> gsm_04_08.c:1282 MSC: Unimplemented GSM 04.08 RR msg type 0x60
<000a> bsc_api.c:402 Sending ChanModify for speech: SPEECH_V1 on channel TCH_F
<0004> abis_rsl.c:1868 (bts=0,trx=0,ts=3,ss=0) IPAC_BIND speech_mode=0x10 RTP_PAYLOAD=3
<0004> abis_rsl.c:1221 (bts=0,trx=0,ts=3,ss=0) CHANNEL MODE MODIFY ACK
<0004> abis_rsl.c:2032 (bts=0,trx=0,ts=3,ss=0) IPAC_CRCX_ACK LOCAL_IP=10.9.1.170 LOCAL_PORT=4002 CON_ID=33 
<0004> abis_rsl.c:1907 (bts=0,trx=0,ts=3,ss=0) IPAC_MDCX IP=10.9.1.170 PORT=4000 RTP_PAYLOAD=3 RTP_PAYLOAD2=0 CONN_ID=33 speech_mode=0x00
<0004> abis_rsl.c:1907 (bts=0,trx=0,ts=2,ss=0) IPAC_MDCX IP=10.9.1.170 PORT=4002 RTP_PAYLOAD=3 RTP_PAYLOAD2=0 CONN_ID=32 speech_mode=0x00
<0004> abis_rsl.c:2042 (bts=0,trx=0,ts=3,ss=0) IPAC_MDCX_ACK CON_ID=33 
<0004> abis_rsl.c:2042 (bts=0,trx=0,ts=2,ss=0) IPAC_MDCX_ACK CON_ID=32 
<0004> abis_rsl.c:619 (bts=0,trx=0,ts=3,ss=0) DEACTivate SACCH CMD
<0004> abis_rsl.c:619 (bts=0,trx=0,ts=2,ss=0) DEACTivate SACCH CMD
<0004> abis_rsl.c:1106 (bts=0,trx=0,ts=2,ss=0): MEAS RES for inactive channel
<0004> abis_rsl.c:1106 (bts=0,trx=0,ts=3,ss=0): MEAS RES for inactive channel
<0004> abis_rsl.c:2051 (bts=0,trx=0,ts=3,ss=0) IPAC_DLCX_IND 
<0004> abis_rsl.c:665 (bts=0,trx=0,ts=3,ss=0) RF Channel Release CMD due error 0
<0004> abis_rsl.c:721 (bts=0,trx=0,ts=3,ss=0) RF CHANNEL RELEASE ACK
<0004> abis_rsl.c:2051 (bts=0,trx=0,ts=2,ss=0) IPAC_DLCX_IND 
<0004> abis_rsl.c:665 (bts=0,trx=0,ts=2,ss=0) RF Channel Release CMD due error 0
<0004> abis_rsl.c:721 (bts=0,trx=0,ts=2,ss=0) RF CHANNEL RELEASE ACK