On the capacity of a DS/CDMA system with automatic on-off switching repeaters

In mobile communication systems, there are areas where signal coverage is not adequately accomplished by base stations. These areas may be underground parking zones, underground stores, tunnels, and insides of buildings, etc. In these areas, repeaters are broadly used as an economical solution. However, the capacity is decreased as the number of repeaters increases because the power of the noise that flows into a base station in the reverse link is proportional to the number of repeaters. The reduction of capacity in the reverse link is no longer negligible in the case that several tens or hundreds repeaters are connected to a base station. We propose automatic on-off switching (AOS) repeater that is switched off automatically when there is no active user within its coverage. With the AOS repeater, we can reduce the unnecessary noise level enhancement when there is no active user within the repeater´s coverage. The reverse link capacity of a DS/CDMA system with AOS repeater is analyzed mathematically and compared with that without AOS. From the numerical results, noticeable improvement with the proposed AOS repeaters is shown