baseband-devel November 2017

baseband-devel@lists.osmocom.org

7 participants
15 discussions

Mobile.cfg test sim
by Zemlyak 21 Nov '17

21 Nov '17

Hi Can anyone tell about "ki xor" in a mobile app-test SIM card data ? -- Sent from: http://baseband-devel.722152.n3.nabble.com/

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Mobile.cfg test-sim
by Zemlyak 20 Nov '17

20 Nov '17

Hi Can anyone say,what does it mean "ki xor" in mobile app when I use a test-sim? Does it ciphyring kc? -- Sent from: http://baseband-devel.722152.n3.nabble.com/

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Calypso vs. SDR PHY
by Mychaela Falconia 19 Nov '17

19 Nov '17

Hello OsmocomBB community, I am the manufacturer of a GSM mobile station development board based on the Calypso+Iota+Rita chipset from TI. The hardware product in question has been created for the primary purpose of running the end-use-oriented GSM+CSD+GPRS modem firmware that was previously maintained by TI and whose maintenance has since been taken over and continued by FreeCalypso, but being based on the Calypso chipset, my board is also capable of running OsmocomBB. The purpose of the present inquiry is to find out whether this hardware product might be of interest to the OsmocomBB community, or if those who wish to run OsmocomBB (as opposed to TI-based FreeCalypso firmware) would be better advised to use an SDR device instead. As I understand it, there are two reasons for why the original incarnation of OsmocomBB (prior to the recent addition of SDR PHY support) used Calypso phones as its physical transceiver instead of USRP-style SDR devices: (1) the work done by the Calypso DSP is already done, hence there was less work for OsmocomBB developers to do, and (2) Calypso phones used to be dirt-cheap, whereas SDR devices cost some non-trivial money. But the dirt-cheap Calypso phone situation is now firmly in the past, and newly made Calypso devices like my FCDEV3B are nowhere close to cheap. The qty-1 retail price for one of my FCDEV3B boards is $500 USD; if someone were to order a large batch (say, 100 boards), I am reasonably confident that the per-unit price can be brought down to $300 USD or maybe even lower, but getting any kind of firm numbers beyond a guesstimate would require actual work, and that work will only be done if I receive some expression of serious and genuine interest. But even if we manage to bring the price down to, say, $200 per board with a really large order quantity, it *still* won't be anywhere near as cheap as old Calypso phones used to be, and the price is still essentially in the same ballpark as a midrange SDR device. Thus with the cost of an SDR device and that of a newly made Calypso device being comparable (or as things stand presently, the Calypso option is more expensive), is there any remaining reason to use Calypso devices as opposed to SDR PHY for OsmocomBB? In other words, is there any solid technical reason (not involving cost) to prefer a Calypso device over SDR PHY for OsmocomBB purposes, or is there not? Which translates into: is there any reason to support running OsmocomBB on FreeCalypso hardware and to market such hw to the OsmocomBB community, or would it be better to tell people that if they want OsmocomBB, they should use an SDR PHY, and leave FC hardware for people like me who are interested in end use applications (as opposed to hacking) using TI-based FC firmware? One argument I have heard against the use of SDR for GSM MS role is that SDR devices supposedly have a difficult time retuning every 4.615 ms, and thus would have a difficult time connecting in the MS role to a GSM network that employs frequency hopping. Is there any truth to that argument, or has that problem already been solved? Are there any other areas in which a chipset like the Calypso that is specifically designed for the GSM MS role would perform better than an SDR device of the kind that are viable cost competitors against newly made Calypso hardware? Just seeking some clarification... M~ P.S. Before anyone says that Calypso chips themselves are no longer made and thus don't constitute a viable option, please note that I can still buy them on the Chinese grey market at least in tens of thousands of pieces, maybe more, and there is no conceivable way that all current phone hacking and phone liberation communities combined can produce enough demand to exhaust that supply. And if someone does order 100 thousand Calypso boards at $300 or so apiece, that would be more than enough money to hire a pirate chip fab to clone every chip in the Calypso chipset.

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Re: Calypso vs. SDR PHY
by Vadim Yanitskiy 19 Nov '17

19 Nov '17

Hello Mychaela, First of all, my congratulations! I have been watching the project you lead for some long time, and it's great to see your achievements. > As I understand it, there are two reasons for why the original > incarnation of OsmocomBB (prior to the recent addition of SDR PHY > support) used Calypso phones as its physical transceiver instead of > USRP-style SDR devices: (1) the work done by the Calypso DSP is > already done, hence there was less work for OsmocomBB developers to > do, and (2) Calypso phones used to be dirt-cheap, whereas SDR devices > cost some non-trivial money. Yeah, moreover I think when OsmocomBB was initiated, the prices of available SDR hardware were higher, than today... > Thus with the cost of an SDR device and that of a newly made Calypso > device being comparable (or as things stand presently, the Calypso > option is more expensive), is there any remaining reason to use > Calypso devices as opposed to SDR PHY for OsmocomBB? In other words, > is there any solid technical reason (not involving cost) to prefer a > Calypso device over SDR PHY for OsmocomBB purposes, or is there not? Personally, for research and development purposes I would preffer SDR. The main reason is that my research scope isn't limited by GSM only, there are other pretty interesting technologies like Iridium, TETRA, GMR, and of course UMTS followed by LTE. > Which translates into: is there any reason to support running OsmocomBB > on FreeCalypso hardware and to market such hw to the OsmocomBB > community, or would it be better to tell people that if they want > OsmocomBB, they should use an SDR PHY, and leave FC hardware for > people like me who are interested in end use applications (as opposed > to hacking) using TI-based FC firmware? SDR PHY isn't finished yet. We only managed to get actual burst transmission working only a couple of weeks ago. At the moment, both AGC and Timing Advance loops are missing, and TX power is not high enough to 'deal' with real base stations... So, I think, Motorola C1XX phones remain the primary hardware back-end for now, thus would be better to tell people about them. > One argument I have heard against the use of SDR for GSM MS role is > that SDR devices supposedly have a difficult time retuning every > 4.615 ms, and thus would have a difficult time connecting in the MS > role to a GSM network that employs frequency hopping. Is there any > truth to that argument, or has that problem already been solved? Are > there any other areas in which a chipset like the Calypso that is > specifically designed for the GSM MS role would perform better than an > SDR device of the kind that are viable cost competitors against newly > made Calypso hardware? Yeah, both frequency popping and neighbour power measurement are the hard topics for SDR PHY. There are some ideas how to implement that, but right now we are keeping this problem aside until all the rest is done ;) With best regards, Vadim Yanitskiy.

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Reliability of no shutdown/shutdown loop
by Holger Freyther 13 Nov '17

13 Nov '17

Hi, as part of adding bindings I wrote code that is doing shutdown/no shutdown every second. Actually I call mobile_init/mobile_exit with a script like this: local start = false osmo.ms().start() function toggle_it() osmo.timeout(1, function() if start then start = false osmo.ms().start() else start = true osmo.ms().stop() end toggle_it() -- start the timer again end end toggle_it() And while debugging I have nothing connected for the l1ctl. This means the l1ctl reset ack is not being received by the application. So when doing the above the following happens. mobile_init() mobile_exit() mobile_init() |-> busy loop of adding a timer already in the tree Turns out that mobile_exit checks the state and then takes an early exit without stopping the timers. So let's use the force option that is meant to not send a IMSI detach. Let's try it again. mobile_init() mobile_exit() mobile_init() |-> busy loop of adding a timer already in the tree Why is that? Even force mobile_exit() will exit early and mobile_init() doesn't take the device out of shutdown. From my point of view a mobile_exit(ms, force) should really take the device down and never fail. Any objections to modify the code for this? regards holger

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baseband-devel November 2017