ree consortia: Microtel, Unitel and Mercury PCN. All 1. Maximum range for a single MS and single BTS. three companies decided to introduce PCN networks based on the 2. Handset, cost, size, weight and battery life. 48/4 Personal communications networks Two power classes for PCN were set 250m W and 1W peak power. BSC also acts as a concentration site for traffic, signalling and OA This is compared with GSM900's five power classes from 800mW & M information. As such the BSC allows flexibility in radio to 20W peak. subsystem development strategies to provide a balance between To derive RF performance requirements such as blocking, output cost and quality. RF spectrum and spurious omissions, it was necessary to define the worst case of MS-BTS coupling. This was achieved by considering 48.4.3 Mobile switching centre (MSC) the worst case of coupling between the BTS-MS, i.e. uncoordinated environment (located close to a non servicing base station antenna The MSC is the 'telephone exchange' of the network and provides and located 30m away). From this a value of 65dB for the worst case call routeing and control, handover, service interworking, intercon- coupling was agreed. nection to other networks and echo control. Collocated with the MSC is the Visitor Location Register (VLR) which provides loca- tion update, location area information, local database and encryp- 48.4 Overview of the PCN network tion key generation. Figure 48.1 shows the main network elements within a PCN Net- 48.4.4 Home location register (HLR) work. The key elements are as follows: The HLR is the network's main database, and contains all the 48.4.1 Base transceiver station (BTS) subscriber's information, e.g. what services the customer has sub- scribed to. The BTS essentially provides the radio coverage and as such pro- The specific functions of the HLR are: number translation, course vides the air interface to the customer. (The air interface will be location, customer profile, and charging. described in more detail later). The BTS also provides a num