How many TRX a E1 supports depends on whether your are using
concentraction or unconcentraction.
In case of unconcentraction each TRX requires 3TS so 1 E1 supports
10 TRX (2TS of speech/Data 1 TS for signalling).
In case of concentraction each TRX requires 2TS if you are going for 16K multiplexing then 1E1 supports 15 TRX.( considering 7TS on TDMA for speech and 1 TS for BCCH and SDCCH , 2TS on E1 is 128 Kbps and on TDMA 7X16Kbps =112Kbps(for speech/data) and 16kbps for TRXC sig so 112+16=128Kbps.
I hope i am correct .