s. Narrowbeam peripheral base station Widebeam peripheral base stations Figure 13-5: Peripheral Coverage of a MAN Target Area Chapter Thirteen Three peripheral Two central base stations base stations Figure 13-6: Mixed Central and Peripheral Coverage of a MAN Target Area Height is generally the greatest asset when locating BS antennas, although care must be taken to ensure that the antenna's beam pattern is directed to provide coverage close to the base of the tower or building, for example by rotating the axis of the antenna downwards below the horizon. Table 13-2: MAN BS Antenna Location Considerations Issue Impact Existing buildings or Existing buildings or towers provide a potentially towers low cost solution for BS antenna location. Barter deals (trading broadband access for antenna siting rights) can also reduce the cost of leasing antenna mounting space on a tower. New towers New towers allow optimum location - improved coverage may offset the additional cost compared to leasing space on existing structures. Local planning regulations will need to be considered in siting new towers. Local terrain Favourable ground elevation can help areal coverage by adding effective height to an antenna location - whether on the periphery or central to the target area. Implementing Wireless MANs Customer Premises Equipment A typical customer premises equipment (CPE) installation will comprise an antenna and radio enclosed in a weatherproof sealed unit, typically mounted on a suitably facing wall of the premises or on a chimney breast (Figure 13-7). The antenna may range from a patch antenna, with 8-14 dB gain for short range links, to a high gain parabolic reflector antenna with 24 dB gain and upwards for longer range. Transmitter power will depend on local regulatory limits with 100-200 mW being typical. Cabling will require outdoor rated Cat 5 Ethernet cable as well as a low voltage DC power line routed back inside the premises. Two approaches can be taken in selecting CPE - one-size-fits-all or subscriber customisation