Interference cancellation for downlink TDMA systems using smart antennas

Unlike CDMA, TDMA may not be considered an interference limited scheme, due to the separation in the time domain of the different users. However, because of frequency reuse, mobiles may suffer interference from signals coming from neighboring base stations that are addressed to other users. It is advantageous to reduce the frequency reuse factor (for example from 7 to 3) and obtain higher capacity, but this obviously increases the interference. To cancel it we propose two approaches that implement what is known as “smart antennas”. The first one is a generalized side-lobe canceller (GSC) with a self-correcting loop, a method which was implemented earlier in downlink CDMA. The second one uses space-time adaptive processing (STAP). In order to obtain and compare the performances, we use the GSM channel models and data structures with frequency reuse factor of three