Hi Neels! Thank you for the reply! I saw the SysmoBTS 1002, and that looks like it'd be exactly what I could use... I just wasn't sure that I could afford one on a hobbyist budget, and while the Ericsson gear may be bulky and require more complicated setups, it is available inexpensively and in pieces that can be digested for hobbyist prices. The Ettus B200 is pretty expensive too. I'm hoping to not have to spend more than $500-700 or so. Also, no harm in recommending your employer's products if you believe in them. That's good testimony. I'll keep my eye out... Thank you so much! -Ben ________________________________ From: Neels Hofmeyr <nhofmeyr(a)sysmocom.de> Sent: Tuesday, September 5, 2023 7:15 AM To: Ben Huntsman <ben(a)huntsmans.net> Cc: openbsc(a)lists.osmocom.org <openbsc(a)lists.osmocom.org> Subject: Re: GPRS hardware recommendations For me, personally, the sysmoBTS 1002 comes to mind. It is small, reliable and works very well with Osmocom. It's my favorite for 2G lab testing. Be aware that the manufacturer is also my employer, but this is my genuine opinion. https://sysmocom.de/products/bts/ Otherwise, it sounds like you could actually use an SDR plus a good timing source, like the Ettus B200 with GPS -- more often than not, dedicated BTS models are also just an SDR inside. It's the easiest to purchase. Check the intended coverage area / nr of users / desired level of reliability... Ericsson stuff is large and heavy, and needs special setups (running the PCU alongside the BSC, E1 instead of IP based voice...) but is of course the more robust, industry proven workhorse with serious wattage. ~N On Tue, Sep 05, 2023 at 01:11:15AM +0000, Ben Huntsman wrote: -- - Neels Hofmeyr <nhofmeyr(a)sysmocom.de> http://www.sysmocom.de/ ======================================================================= * sysmocom - systems for mobile communications GmbH * Alt-Moabit 93 * 10559 Berlin, Germany * Sitz / Registered office: Berlin, HRB 134158 B * Geschäftsführer / Managing Directors: Harald Welte

Hi Keith- Thanks for the questions! I have no particular attachment to the Ericsson gear, it just seemed to be the most plentiful and least expensive from what I saw on eBay. The RBS 6601 2U chassis with a DUG 20 seemed pretty reasonable, and attaching something like an RRUS 12. Don't laugh, and since this is just for hobbyist tinkering, what I'm trying to do is get a few old BlackBerries running. They're 7290's, so only support GPRS, though I think they may support EDGE as well but I'm a little unsure on that. When you saying that GPRS is unusable for most applications, is that because of limitations in the osmocom stack, or just because GPRS is primitive when compared against 4G/5G ? I looked at the nanoBTS also, but the ones that can operate in 900MHz and hence not be illegal in the US are still pretty expensive. Though you do have a good point that factoring in the cost of a -48v power supply, the 6601, DUG20, and RRUS, it'd probably be pushing $1k anyway. What Ericsson gear do you have? Thanks much! -Ben ________________________________ From: Keith <keith(a)rhizomatica.org> Sent: Wednesday, September 6, 2023 12:48 PM To: openbsc(a)lists.osmocom.org <openbsc(a)lists.osmocom.org> Subject: Re: GPRS hardware recommendations Hi Ben, I'd be interested to know more precise details about what Ericsson gear you are looking at. This is for 2G GPRS experiments, correct? I'd also wonder what it is you are interested in doing with GPRS, I've generally found that it's pretty much unusable for most applications running on a modern IP stack. You can do ICMP "ping", yes.. but not so much more. Maybe with (only) one phone on a TRX fully configured for max packet data channels, you should be able to establish a connection to a web server, XMPP server or even an ssh session. If you configure EGPRS a.k.a EDGE, then there are more possibilities, but I think the EDGE support in osmocom for the RBS is still considered very much cutting-er..edge.. I have some Ericsson RBS gear and I have not as yet, got it up and running with either GRPS or EDGE. (Not saying it should be difficult, it just got pushed down my priority list) We do know that it's possible, although sustained operation with multiple MS, I believe, has yet to be tested. The Ericsson RBS gear also presents a not-insignificant need to look at power supply, (and consumption) RF attenuation, and last but not least, Cooling!! The SysmoBTS 1002, on the other hand, is pretty much plug-and-play at this point. Maybe somebody else can expand on GPRS support on them, as I don't have one, but an Ip.access nanoBTS might be found within the budget you mentioned.

Hi Keith! That is awesome! Very nice collection! I'm not sure what it'll do, but the BlackBerry 7290, being from that era, certainly shouldn't generate so much traffic. Would a SIU or a TCU eliminate the need for E1/T1? Or, apparently the DUS 4102 can do GSM, LTE, CDMA, and also uses IP uplinks instead of E1's. Have you (or anyone here) tried one before? The DUS looks pretty inexpensive and now I'm leaning towards an RBS 6601 with a DUS 4102, instead of a DUG 20 + TCU 02. To power it, I was thinking about picking up one of those Valere or Eltek 1U or 2U rectifier shelves. Anyone else tried one? Thanks again! -Ben ________________________________ From: Keith <keith(a)rhizomatica.org> Sent: Friday, September 8, 2023 2:21 PM To: Ben Huntsman <ben(a)huntsmans.net>et>; openbsc(a)lists.osmocom.org <openbsc(a)lists.osmocom.org> Subject: Re: GPRS hardware recommendations Hi Ben. On 07/09/2023 00:50, Ben Huntsman wrote: Don't laugh, and since this is just for hobbyist tinkering, what I'm trying to do is get a few old BlackBerries running. They're 7290's, so only support GPRS, though I think they may support EDGE as well but I'm a little unsure on that. I never had a blackberry so I don't know either. I noticed that with almost any kind of Android phone, it's going to generate so much traffic as soon as it sees a network connection that it will saturate the GPRS itself. - I did not spend a huge amount of time making an analysis of this, but what can be observed is a LOT of re-transmissions (from both sides), and then TCP resets from the remotes. I suppose it's to be expected. the stack in the phone is not seeing ACKs quickly enough, so re-transmits. same on the other side.. (assuming the ACK as lost?) I'm no expert in TCP/IP, although I understand TCP is supposed to handle this by backing off, but I assumed what I was seeing was servers that are so busy they are configured with some kind of a "no, you're too slow and I'm not going to wait around for you" policy. In production setups, with EDGE, and some several 100 phones connected, the same situation arises, but I did manage to get control of it by heavy use of iptables and TARPIT - only allowing traffic to IM services, and therefore letting at least those have some chance of establishing a connection. I assume it's mainly all the phone-home stuff that gets in the way (most is https, most is to google) - Probably app stores checking for updates, sending google location logs, that kind of thing. Androids for example, won't back off if you don't resolve the DNS they ask for, (in some cases they don't care about configured DNS, they always ask 8.8.8.8 and 8.8.4.4 and if they get a NXDOMAIN or anything unexpected, they just keep on hammering away, expecting to get through. While it'd of course be great if someone else was also playing around with GPRS/EDGE and the DUG, If it's just for hobbyist tinkering, I have successfully connected phones on the lab-desk, with EDGE at reasonable speeds, with the LimeSDR-mini and a mini desktop based on one of these: https://www.mitacmct.com/IndustrialMotherboard_PD11BI_PD11BI But I understand your mileage may vary greatly there depending (maybe?) on the actual lime board you happen to have, the temperature and how sensitive your phones are to clock drift. Though you do have a good point that factoring in the cost of a -48v power supply, the 6601, DUG20, and RRUS, it'd probably be pushing $1k anyway. At least the RRUS doesn't need any active cooling, and the 6601 fan system can be controlled by the DUG. What Ericsson gear do you have? Some 6601, a bunch of DUG 20, some DUL and some RUS 01 B5/B8, plus some PSU AC 01 (they need a cooling solution too) Last but not least, even though it's not Ericsson, I have to mention of course the sysmocom icE1usb as an integral part of the system! Thanks much! Good luck! k/ -Ben