On Wed, Aug 14, 2019 at 01:14:31PM +0300, Mykola Shchetinin wrote:

Hello, dear Community,

Has anybody tested how cell handover works in 3G with Osmocom software?

I am quite positive that no 3G handover could have been possible, because osmo-msc would need to (instruct its MGW to) redirect the RTP to a different femto cell, and no such code is implemented.

I assume 3G handover when using femto cells (with an RNC each) uses the BSSMAP Handover Required (etc.) messages. We have only recently added inter-BSC handover on 2G, meaning that we have support for these BSSMAP Handover messages only since about May this year. It was duly tested for 2G, but so far there was no funding to investigate inter-RNC handover, i.e. on 3G.

With the new BSSMAP Handover messages implementation in osmo-msc, we do have a good chance to enable inter-RNC handover without too much effort, only someone needs to spend time looking into it and testing. The first step would be to tickle an actual femto cell (e.g. nano3G) into sending a BSSMAP Handover Required to the MSC; then one could play through the handover procedure and implement any missing bits for the 3G code paths in osmo-msc.

~N