Cochannel interference canceler using a CMA adaptive array antenna

A CMA adaptive array is capable of extracting a single signal from multiple cochannels without a reference signal. However, the captured signal is not necessarily the desired signal. Also, since CMA is for a signal of constant envelope, the receiving characteristic degrades when the envelope of the signal changes, depending on the band limitation. This paper proposes a cochannel interference canceler which estimates the interference signal component in the received signal and eliminates the interference component from the received signal. In addition, an intermittent weight updating CMA method is proposed, where the degradation of the receiving characteristic is avoided by intermittently updating the weight at the code decision point at which the constant envelope characteristic is maintained for the signal whose envelope changes depending on the band limitation. The simulations of GMSK and π/4-shifted DQPSK confirmed that the proposed canceler effectively reduces the influence of the cochannel interference. It was also found that when the fading change was small in the π/4-shifted DQPSK, the cochannel interference reduction effect could be improved by combining the interference canceler and intermittent weight updating CMA method. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(10): 92–102, 2000