Hi all, I have experienced this open power control loop a tedious beast when using OpenBTS - it is a PITA to find settings that work reliably.
Ralph. -----Original Message----- From: OpenBSC [mailto:[email protected]] On Behalf Of Alexander Chemeris Sent: Wednesday, July 29, 2015 03:26 To: Sipos Csaba Cc: Ivan Kluchnikov; OpenBSC Mailing List Subject: Re: Using GPRS Hi Sipos, A couple general notes with a remark that I haven't touched the GPRS code for a long while: Power control loop for GPRS is separate from the power loop for the CS domain. IIRC it should be done in PCU, but it's not implemented yet. So right now IIRC the MS should be in an open loop power control mode, deducing its Tx power from its Rx level. I can't comment on the dB values, because I've never used B200. But if you use fairwaves/master branch, it can detect clipping when the signal is of too high power (check the logs). You can also enable debug logging level for osmo-trx to assess demodulation quality visually (there should be few to none '-' in the demodulated bursts). If you see the demodulation is perfect, but the issue is still there - you have to dig the layers upwards. On Sun, Jul 26, 2015 at 2:02 PM, Sipos Csaba <[email protected]> wrote: > I will try to give you as many feedback as possible. :-) > > I finally have a more or less working setup. At least there is no crash > whatsoever, and the PS domain is working, the UE can attach, activate PDP, > transfer data to some extent. > > For example when i tried to ping the TUN interface, I got 2500-2600ms > latency. I tried with both the "A" and the "B" algorithm, it was pretty much > the same. I seen a lot of PRACH happening, so I checked the radio parameters: > > With power=0 and rxgain=15 at ARFCN=885 I got -55dBm RSSI at the UE, and -40 > -45dBm RSSI at the BTS. The freqency I use is completely clean, and I use a > proper duplexer and an omni antenna. The UE is 2 meters a way, line of site. > The SNR measured by the UE is around 20-22 dB in DL direction. The > ms-power-loop was set to -15, the max MS power was 20dBm. > > So the RF part seems correct, and still I got these very high latencies. In > comparison with OpenBTS and the same setup, I got around 350-500ms latency > with multislot. > > Maybe the UE goes to IDLE too fast for a ping test? > > Regards, > Csaba > > ----- Eredeti üzenet ----- > Feladó: "Ivan Kluchnikov" <[email protected]> > Címzett: "Sipos Csaba" <[email protected]> Másolatot kap: > "Alexander Chemeris" <[email protected]>, "OpenBSC Mailing > List" <[email protected]> Elküldött üzenetek: Vasárnap, 2015. > Július 26. 14:00:28 > Tárgy: Re: Using GPRS > > Hi Sipos, > > Osmo-TRX master branch should be also fine for gprs, you can use it. > Thank you for report, we will fix osmo-trx fairwaves/master branch soon. > > 2015-07-26 14:39 GMT+03:00 Sipos Csaba <[email protected]>: > >> Sorry for this last one, GPRS was not enabled in openbsc.conf. >> >> The PCU is now talking with the SGSN. >> >> But the compilation probem with Osmo-TRX fairwaves/master branch is >> still there. >> >> Regards, >> Csaba >> >> ----- Eredeti üzenet ----- >> Feladó: "Sipos Csaba" <[email protected]> >> Címzett: "Ivan Kluchnikov" <[email protected]>, "Alexander >> Chemeris" <[email protected]> Másolatot kap: "OpenBSC >> Mailing List" <[email protected]> Elküldött üzenetek: >> Vasárnap, 2015. Július 26. 12:30:50 >> Tárgy: Re: Using GPRS >> >> Dear Ivan, Alexander, >> >> I encountered the following issues: >> >> During compiling of OpenBSC (fairwaves/master), the pcap.h was missing. >> The configuration script was not detecting this missing file. >> "apt-get install libpcap-dev" solved this issue. >> >> The fairwaves/master branch of osmo-trx produces the following issue >> durign compilation: >> >> ================================ >> >> Making all in x86 >> make[3]: Entering directory `/root/new_openbsc/osmo-trx/Transceiver52M/x86' >> CC ../common/convolve_base.lo >> CC convert.lo >> In file included from convert.c:33:0: >> /usr/lib/gcc/x86_64-linux-gnu/4.8/include/smmintrin.h:31:3: error: >> #error >> "SSE4.1 instruction set not enabled" >> # error "SSE4.1 instruction set not enabled" >> ^ >> convert.c: In function '_sse_convert_si16_ps_16n': >> convert.c:49:3: warning: implicit declaration of function >> '_mm_cvtepi16_epi32' [-Wimplicit-function-declaration] >> m2 = _mm_cvtepi16_epi32(m0); >> ^ >> convert.c:49:6: error: incompatible types when assigning to type '__m128i' >> from type 'int' >> m2 = _mm_cvtepi16_epi32(m0); >> ^ >> convert.c:50:6: error: incompatible types when assigning to type '__m128i' >> from type 'int' >> m4 = _mm_cvtepi16_epi32(m1); >> ^ >> convert.c:53:6: error: incompatible types when assigning to type '__m128i' >> from type 'int' >> m3 = _mm_cvtepi16_epi32(m0); >> ^ >> convert.c:54:6: error: incompatible types when assigning to type '__m128i' >> from type 'int' >> m5 = _mm_cvtepi16_epi32(m1); >> ^ >> make[3]: *** [convert.lo] Error 1 >> make[3]: Leaving directory `/root/new_openbsc/osmo-trx/Transceiver52M/x86' >> make[2]: *** [all-recursive] Error 1 >> make[2]: Leaving directory `/root/new_openbsc/osmo-trx/Transceiver52M' >> make[1]: *** [all-recursive] Error 1 >> make[1]: Leaving directory `/root/new_openbsc/osmo-trx' >> make: *** [all] Error 2 >> >> ================================= >> >> Please note that the master branch of Osmo-TRX compiles just fine. >> >> Do any of you have an idea what could be the problem? >> >> Thanks! >> >> Csaba >> >> ----- Eredeti üzenet ----- >> Feladó: "Sipos Csaba" <[email protected]> >> Címzett: "Ivan Kluchnikov" <[email protected]> Másolatot >> kap: "OpenBSC Mailing List" <[email protected]> Elküldött >> üzenetek: Vasárnap, 2015. Július 26. 11:35:42 >> Tárgy: Re: Using GPRS >> >> Thanks Ivan, >> >> Will try that and report back. >> >> Regards, >> Csaba >> >> ----- Eredeti üzenet ----- >> Feladó: "Ivan Kluchnikov" <[email protected]> >> Címzett: "Sipos Csaba" <[email protected]> Másolatot kap: >> "Alexander Chemeris" <[email protected]>, "OpenBSC Mailing >> List" <[email protected]> Elküldött üzenetek: Vasárnap, 2015. >> Július 26. 10:56:51 >> Tárgy: Re: Using GPRS >> >> Hi Sipos, Omar, >> >> You should use the following branches: >> >> libosmocore branch master >> >> libosmo-abis branch master >> >> osmo-trx branch fairwaves/master >> >> osmo-bts branch fairwaves/master ( use ./configure --enable-trx) >> >> openbsc branch fairwaves/master >> >> osmo-pcu branch master (use ./configure --enable-sysmocom-bts ) >> >> openggsn branch master >> >> Also if you use the same machine for sgsn, bts and pcu, you should >> change openbsc.cfg, instead of: >> gprs nsvc 0 local udp port 23000 >> gprs nsvc 0 remote udp port 23000 >> use different ports, for example: >> gprs nsvc 0 local udp port 5948 >> gprs nsvc 0 remote udp port 23000 >> >> -- >> Regards, >> Ivan Kluchnikov. >> http://fairwaves.ru >> >> > > > -- > Regards, > Ivan Kluchnikov. > http://fairwaves.ru -- Regards, Alexander Chemeris. 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