hi,
i did a lot of resarch and testing on cell selection and re-selection process the last two week.
the cell selection process, network selection process (manual and automatic) and mobility management process were already implemented in OsmocomBB a long time, but turned out to be buggy and incomplete. i made test drives to check the process and debugged it.
the re-selection process is new. it is used to track surrounding cells while listening to the BCCH of the current cell (camping on a cell). special extension to the layer1 firmare is used to measure neighbour cells. if an neighbour cell becomes 'better', the mobile switches to that cell, depening on different criteria. now it is possible to move with OsmocomBB.
the re-selection process is not handover! handover is a process where a phone switches between cells while doing a call. handover is one next step to implement. the process is a little more complex, because it requires not only neighbour cell measurements, but also syncing to them without interrupting the traffic channel. most layer 3 stuff of handover is already implemented.
if you like to play and test your moving OsmocomBB, you can check out the "jolly/roaming" branch. it contains the extension to layer1, as well as sim reader and fixes from "sylvain/testing" branch. use both "mobile" and "layer1" firmware from this branch.
in order to see some process at VTY, you can do:
enable monitor network 1 (continously display the strongest cell and neighbour cells) show ms 1 (to see current states) show neighbour-cells 1 (to see a more detailed current list of neighbours)
andreas
Hello Sir: I am working on the implementation of call handover (in dedicated mode) to the osmocom-bb code. Any progress from your side or any insights that you feel are necessary for this implementation would be highly appreciated.
Regards, Asghar Mustafa.
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Hello Sir: I am working on the implementation of call handover (in dedicated mode) to the osmocom-bb code. Any progress from your side or any insights that you feel are necessary for this implementation would be highly appreciated.
Regards, Asghar Mustafa.
-- View this message in context: http://baseband-devel.722152.n3.nabble.com/cell-re-selection-tp3089620p40267... Sent from the baseband-devel mailing list archive at Nabble.com.
Hi Asghar,
On Mon, Feb 29, 2016 at 12:16:59AM -0700, Patrick wrote:
I am working on the implementation of call handover (in dedicated mode) to the osmocom-bb code. Any progress from your side or any insights that you feel are necessary for this implementation would be highly appreciated.
I think we had this didscussion several times in the past. Maybe it was at physical meetings of developers only and not on the list yet, sorry.
The necessary code on the Layer2/3 side should all be implemented. The remainder is the wokr required in the layer 1 on the phone, where the problem of synchronizing to the neighbor cells has to be solved.
The various BTSs all have their own clock, and they are not synchronized to one another. In order to do hand-over, the MS involved needs to send regular measurement reports of neighbor cells. In order to do so, it needs to switch to the neighbor cell ARFCN and perform both a power measurement as well as a Sync Burst detection to obtain the BSIC.
So the L1 needs to * be able to maintain synchronization parameters not only for the serving cell but also for neighbor cells * be able to switch + re-sync to a neighbor cell in the idle slot of the 26-multiframe. Iterate over all neighbor cells in successive idle slots. * provide rx level + BSIC readings for those neighbors to l2/l3 on the PC
Regards, Harald
baseband-devel@lists.osmocom.org