On-Frequency Repeater Deployment for Wireless Radio Networks : Investigations of fixed repeater networks in UMTS and HIPERLAN II systems under Rayleigh fading

In the mobile radio environment, base stations are installed at the location where the coverage area receives adequate signal power that makes the communication possible. However, due to the nature of wave propagation and the natural features of the environment, such as valleys or the shadows of intervening mountains, as well as man-made objects such as tunnels or high-rise buildings in the vicinity of wave propagation, severe fading of the signal amplitude will result, creating dead spots areas. These areas need to be patched, especially in prime or high-populated traffic areas. A good reliable signal can be obtained by installing an additional base station, but this approach would increase the signalling complexity by increasing handover between cells. Furthermore, it is not cost effective to build an additional BS to patch a small shadow area, due to the high network investment that would be required. An alternative to patching these areas is by using On-Frequency repeaters, also known as Cell Enhancers, as they constitute much simpler and cheaper techniques as well as involving shorter "off-air" periods for obtaining reliable radio coverage.