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