Related to DR-TRX, in ALU, it also has a relation to Abis TS.
As I know, if Full Rate, then it will allocate 64 kbps (1 TS Abis), and when HALF RATE, it applies 32 kbps Abis(2 GCHs or 2 nibbles of Abis).
But sometimes, when I tried to apply HR in a certain site, it could not be done. The reason was “no TS Abis provided in Abis”. I wonder, in FULLRATE, it had no problem at Abis TS, but when we want to apply HALFRATE (becomes ENABLE), there was no TS Abis provided, instead, HALFRATE just only take a half of 1 TS Abis.
Its a typical Alcatel Problem. Actually there are 3 sorts of ABIS configurations different vendors use
1. ABIS is also Halfrate capable and as HR is enabled on the cell, HR also gets activated for ABIS.
2. ABIS is not HR capable and if you define HR then you have to add additional Abis respources.
3. ABIS Allocation is dynamic here both of the above are applicable but there might be cases where there is no TCH congestion on the cell but calls are rejected due to ABIS level congestion.
Alcatel uses fixed configuration (2nd option) so you have to configure a TS on Abis for each TS on Radio and for HR enabled since Abis is not HR capable then you have to add additional ABIS.