l. When the configuration becomes 2 + 1 + 1, the next TRX on the first cell is assigned TS 5 and TS 6 and SO on. The methodology is simple to implement but difficult to manage after some time. 3.10.2 Block TS Allocation In this model, a block is reserved for each cell. Usually there are three sectors for each BTS. Therefore, TS 1 to TS 8 are reserved for traffic in the first cell, TS 9 to TS 16 for the traffic in the second cell and TS 17 to TS 24 for the traffic in the third cell. This means that the configuration of the BTS is 1 + 0 + 0 and the TRX will be assigned TS 1 and TS 2. However, if the configuration is 1 + 1 + 1, then the TS assigned will be TS 1 and TS 2 for cell 1, TS 9 andTS 10 forcell2andTS 17andTS 18 forcell3 Although using this methodology causes the spare capacity to be fragmented, the upgrades are easier. Bits are reserved for transmission management (discussed later), controlling the loop, i.e. the direction in which traffic will flow under normal conditions, and in conditions when the link breaks. 3.10.3 TS Grouping TSs can be grouped according to TRXs, BTSs or by usage. When grouping the TS by the TRX is done, the traffic and signalling channels of the given TRX are kept together. This is valid for both the block and Timeslot Planning Management Management TRX 1 TRX 1 TRXSIG1 TRX 2 TRX 2 TRX 3 TRXSIG 2 TRX 4 TRX 3 TRXSIG3 TS 10 TRX 4 TS 11 TS 12 TRXSIG4 TS 13-24 TS 13-24 TS 25 TRXSIG BCFSIG TRXSIG2 TS 26 TRXSIG3 TRXSIG4 TS 27 TS 28 TS 29 TS 30 BCFSIG TS 31 PILOT BITS, Management Bits PILOT BITS, Management Bits (a) Grouping TS by usage (b) Grouping TS by TRX Figure 3.68 TS allocation strategies the linear allocation. In this case, the BTS signalling channels are placed at a different location. In the case of grouping by the BTS, the traffic and signalling channels (both TRX and BCF) are placed together. In the case of TS grouping by usage, the traffic channels and signalling (SIG) are at different locations; i.e. all the traffic channels are placed together and all the signalling channels a