Cochannel interference suppression for constant modulus signals

In this paper we investigate Single Antenna Interference Cancellation (SAIC) for the GSM/EDGE system with the GMSK modulation. If the received signal is a superposition of the desired signal and Constant Modulus (CM) interference, the semi-blind method proposed by Berangi and Leung in [1] can be used to suppress interference and thereby improve the receiver performance. However, they assume ideal channel state information, which is not available in practical cellular systems. Furthermore, the CM-SAIC algorithm is rather sensitive for channel estimation error and the suppression gain can be lost due to inaccurate estimation. For instance, the CM-SAIC with Least Squares (LS) channel estimation provides hardly any gain. Therefore we introduce a novel iterative channel estimation method based on the CM criterion. When combined with the CM-SAIC detector significant performance improvement can be achieved. In the presence of single dominant interfering signal we obtain up to 5 dB gain in TU3 channel.