ar location area. MSC 2 pages that location area. B answers, conversation begins. The number of BTS's supported by a BSC depends upon several considerations: traffic, type of BTS and BSC, local area cost deter- mination. The answer can range between 1 and 128 BTS's, or even 48.6 Planning a PCN higher. However, it is important to decide, when planning the network, which BTS's will be parented on to which BSC. There are When planning a PCN, it is necessary to consider a number of areas, three main means of connecting BTS's to BSC's: star, ring and a including the services to be offered. The definition of services will combination of the two. determine the selection of infrastructure suppliers, signalling sys- items to be used, as well as allowing operators to develop traffic Typical star configuration. plans. Figure 48.3 shows a star configuration. This is simple to implement 48.6.1 and, subject to traffic, consists of a minimum of one 2Mbit/s path Physical network realisation between each BTS and BSC. The main advantage of this type of The development of the physical network implementation requires answers to: 1. What geographical coverage is required? 2. What is the traffic density per area? 3. What is the guaranteed service level, i.e. at street level or in buildings? With this information, it is possible to plan the radio network and deploy BTS with sufficient transceivers to service demand. This then provides the customer interface. Next the BSC's must be deployed to control the radio subsystem. Their function is to control the BTS. The location of the BSC is based upon a number of considerations: 1. How many BTS's does the BSC control? Figure 48.3 Star configuration of BTS's 2. What is the traffic handling capacity of the BSC? 48/6 Personal communications networks configuration is that it is easy to augment routes. Growth at one 48.6.1.2 BSC -MSC connection particular site has no particular impact on growth at other sites. However, the main disadvantages are: The connection of BSC's to MSC presents interestin