1> yes, one radio ts can carry many PDCH… which means that the radio ts is shared between different users !
of course, each user will have less throughput. for instance, if you locate 3 PDCH on one TS, the throughput will be divided by three. It is like multiplexing…
2> yes you will have 5 free TS. But if you leave them at “free”, they won’t be used for E-GPRS. You need to define them as “extra ts”, not “free ts”.
3> structure of abis… mmm. You can start from the typical “only voice” configuration (with TRAU, O&M, Signalling abis timeslots). Nothing will change here, except that you must define some of your FREE TS as EXTRA TS. Normally, for a 3×4 site, you should define at least 5 EXTRA TS, to allow MCS9. If your EDGE traffic is high, then 5 won’t be enough.
Abis configuration for EDGE should not be frozen : you can start with 5 extra TS, and closely monitor the QOS / Drive-tests for this site.
After a certain period of monitoring (days, weeks, months !), you might notice that the EDGE traffic has increased. There are more EDGE subscribers. Then, to satisfy your customers, you can decide to add additional EXTRA TS. And so on…