re placed together, as shown in Figure 3.68. 3.10.4 TS Planning in the EDGE Network TS planning in EDGE networks becomes slightly more complicated if the concept of dynamic Abis is used. In the GSM and GPRS transmission networks the Abis is known as 'static Abis' while network, Abis becomes more dynamic (as seen in Section 3.6.2). Due to the transfer of the packet data, the number of Abis required for a single fully loaded BTS (e.g. 4 + 4 + 4) is usually more than one. Thus, the TS allocation in the EDGE transmission networks is different from those in the GSM and GPRS networks as some TSs are dedicated for the packet data. Thus, as seen in Figure 3.69, TSs in the pool are placed together while traffic and signalling channels are placed separately (TS grouping by usage). It is important to note that the way the TSs in the pool are assigned depends upon the equipment vendor design specifications (shown in Figure 3.68). Transmission Network Planning and Optimisation LINK MANAGEMENT TCH.1 TCH.7 TCH.1 TCH.4 TCH.7 TCH.1 TCH.4 TCH.7 TCH.1 TCH.7 TCH.1 TCH.4 TCH.7 TCH.1 TCH.4 TCH.7 TCH.1 TCH.4 TCH.1 TCH.7 TCH.1 TCH.7 TCH.1 DAP Pool TCH.1 TCH.4 TCH.1 TCH.4 TRXSIG1 OMUSIGI TRXSIG2 OMUSIG2 TRXSIG3 OMUSIG3 TRXSIG4 OMUSIG4 TRXSIG5 OMUSIG5 TRXSIG6 OMUSIG6 TRXSIG7 OMUSIG? TRXSIG8 OMUSIGO TRXSIG9 OMUSIG9 TRXSIG10 OMUSIGIO TRXSIG11 OMUSIG11 TRXSIG12 OMUSIG-12 Figure 3.69 Dynamic Abis (OMU, operation and maintenance unit) 3.11 Synchronisation Planning The cellular networks generally consist of three types of equipment: asynchronous, plesiochronous and synchronous. Asynchronous equipment, e.g. PDH multiplexers with bit stuffing and line systems at higher than the primary bit rate, is used to transport data between digital exchanges. PDH networks have islands of synchronous networks that are connected to each other by the highly accurate synchronous clocks. Synchronous networks do not require any synchronisation clocks. Because of the advantages of using SDH networks, the backbones are usually made of the SDH while the access networ