GPSDO is mounted upon the B210. And I executes this command "./osmo-trx -g -e".

My timeslot config is 3 TCH/F + 3 PDCH.

________________________________ From: Neels Hofmeyr nhofmeyr@sysmocom.de Sent: Thursday, March 1, 2018 12:27 To: XINKE ZHANG Cc: osmocom-net-gprs@lists.osmocom.org Subject: Re: Data Rate of EGPRS is Too Low

On Wed, Feb 28, 2018 at 12:53:21AM +0000, XINKE ZHANG wrote:

Hi all,

I have set up the EGPRS network using software bundles (osmo-nitb + osmo-bts-trx + osmo-trx + osmo-pcu + osmo-sgsn + openggsn) based on the USRP B210 platform. Now the cell phone can connect to the EGPRS network, but the network is not stable and the data rate is too low (only about 8kbs).

- do you have a proper timing source connected to the B210? - what's your timeslot config?

~N

I'm sure that B210 has a GPSDO. I execute 'uhd_usrp_probe' to prove it.

My entire config files are attached here. Pls help check it. Thanks.

From: Neels Hofmeyr nhofmeyr@sysmocom.de Sent: Friday, March 2, 2018 3:01 To: XINKE ZHANG Cc: osmocom-net-gprs@lists.osmocom.org Subject: Re: Data Rate of EGPRS is Too Low

On Thu, Mar 01, 2018 at 01:40:56PM +0000, XINKE ZHANG wrote:

GPSDO is mounted upon the B210. And I executes this command "./osmo-trx -g -e".

Make sure that your B210 actually contains a GPSDO, I myself once thought I had one, but all I did was connect a GPS antenna to a dead socket on the B210. So a B210 even though it has a connector for a GPSDO may have no GPSDO inside... Also the -g option won't tell you if there is no GPSDO inside, it'll just all work the same as before, i.e. unreliably.

My timeslot config is 3 TCH/F + 3 PDCH.

Would you mind posting your entire config...

I don't really remember what rates I got out of GPRS, IIRC about 10 kbyte/s with 3 PDCH was the ballpark. I Never actually tried EGPRS but I assume it should be at least marginally faster?? Does anyone else know more details?

~N

Hello Xinke, I'm a graduate student at the University of Washington, and just brought up an EGPRS/GPRS network with an Ettus B210/osmo-trx. My B210 has a GPSDO as well. I'm just getting started on this project (so I'm unfortunately not the expert you are looking for), but I can corroborate that I am also seeing very limited single user throughput in EGRPS and vanilla GRPS (6-8kbps maximum measured via iperf). My network is built with the latest split components running on a debian9 virtual machine via virtualbox. I'll attach my configs here if they're helpful. I also have access to a litecell1.5 and will be bringing up the network on it in the next few weeks, so I'll be able to report if it behaves any better. The litecell setup will also be running on dedicated hardware to rule out any strangeness from virtualbox. Sorry I don't have any other clues at this time, but I can at least confirm Neels's analysis above and rule out the impact of running the old nitb and ggsn. Cheers, -Matt Johnson

On Mon, Mar 5, 2018 at 2:15 PM, Neels Hofmeyr nhofmeyr@sysmocom.de wrote:

On Sat, Mar 03, 2018 at 12:18:52PM +0000, XINKE ZHANG wrote:

...

I'm sure that B210 has a GPSDO. I execute 'uhd_usrp_probe' to prove it.

I'm not familiar with it, but if you say so.

...

My entire config files are attached here. Pls help check it. Thanks.

It all looks good to me. Two minor notes:

• the pcu config once needed 'two-phase-access' to function reliably, but

this is no longer needed.

• you seem to be running an old version of the ggsn. The new one is called osmo-ggsn with a config file style and vty interface like the other osmo programs. However, this should not affect your downlink throughput.

• you also seem to run osmo-nitb, we have moved to separate programs, being osmo-hlr, osmo-msc and osmo-bsc. Refer to http://osmocom.org/projects/cellular-infrastructure/wiki/

Osmocom_Network_In_The_Box This should, however, not affect your downlink throughput, either.

So yeah, sorry, but I have nothing of weight to add. Maybe someone else here has deeper knowledge of EGPRS and SDR based BTS?

~N

Hello Xinke, I believe I've found the culprit. It took me longer than I thought it would, but I have a full Litecell 1.5 network up and running now. I continued to see poor throughput though, even with the Litecell instead of a B210! Over the last few days I worked through the different components, and discovered that it seemed like the bottleneck was in the PCU. That lead me to take a look at the osmo-pcu issue tracker, where I found the following ticket: https://osmocom.org/issues/1524 . It looks like the PCU has trouble communicating with the basebands of some phones, particularly phones with Mediatek chipsets. I was able to get ahold of an iPhone8 for testing (Qualcomm baseband), and was able to get a more reasonable 400kbps of throughput (with healthy PCU packet counters, vs my lab test phone that had large numbers of PCU TBF timeouts). It just so happened that my main lab test phones were all low end models with Mediatek chipsets, even though they were in very different form factors and from different manufacturers. Hopefully this is helpful-- let me know if you've found another possible explanation for your observed low throughput. Regards, -Matt J.

On Thu, Apr 12, 2018 at 3:43 PM XINKE ZHANG xinke.zhang@hotmail.com wrote:

Hi Matthew,

I'm sorry for late reply.

I have also tested the latest split components running on a xubuntu 14.04 machine, but the throughput is very limited. I buy a test phone, and find that the dl bler is so high. In my opinion, the high dl bler causes the low throughput. Nowadays, I'm trying to locate issues, but there is no progress.

Best Regards,

Xinke

---

*From:* Matthew Johnson matt9j@cs.washington.edu *Sent:* Wednesday, April 4, 2018 16:54 *To:* Neels Hofmeyr *Cc:* XINKE ZHANG; osmocom-net-gprs@lists.osmocom.org *Subject:* Re: Data Rate of EGPRS is Too Low

Hello Xinke, I'm a graduate student at the University of Washington, and just brought up an EGPRS/GPRS network with an Ettus B210/osmo-trx. My B210 has a GPSDO as well. I'm just getting started on this project (so I'm unfortunately not the expert you are looking for), but I can corroborate that I am also seeing very limited single user throughput in EGRPS and vanilla GRPS (6-8kbps maximum measured via iperf). My network is built with the latest split components running on a debian9 virtual machine via virtualbox. I'll attach my configs here if they're helpful. I also have access to a litecell1.5 and will be bringing up the network on it in the next few weeks, so I'll be able to report if it behaves any better. The litecell setup will also be running on dedicated hardware to rule out any strangeness from virtualbox. Sorry I don't have any other clues at this time, but I can at least confirm Neels's analysis above and rule out the impact of running the old nitb and ggsn. Cheers, -Matt Johnson

On Mon, Mar 5, 2018 at 2:15 PM, Neels Hofmeyr nhofmeyr@sysmocom.de wrote:

On Sat, Mar 03, 2018 at 12:18:52PM +0000, XINKE ZHANG wrote:

...

I'm sure that B210 has a GPSDO. I execute 'uhd_usrp_probe' to prove it.

I'm not familiar with it, but if you say so.

...

My entire config files are attached here. Pls help check it. Thanks.

It all looks good to me. Two minor notes:

• the pcu config once needed 'two-phase-access' to function reliably, but

this is no longer needed.

• you seem to be running an old version of the ggsn. The new one is called osmo-ggsn with a config file style and vty interface like the other osmo programs. However, this should not affect your downlink throughput.

• you also seem to run osmo-nitb, we have moved to separate programs, being osmo-hlr, osmo-msc and osmo-bsc. Refer to

http://osmocom.org/projects/cellular-infrastructure/wiki/Osmocom_Network_In_... This should, however, not affect your downlink throughput, either.

So yeah, sorry, but I have nothing of weight to add. Maybe someone else here has deeper knowledge of EGPRS and SDR based BTS?

~N