Signal acquisition and tracking with adaptive arrays in wireless systems

The dynamic performance of adaptive arrays in wireless communication systems is considered. With an adaptive array, the signals received by multiple antennas are weighted and combined to suppress interference and combat desired-signal fading. In these systems, the weight adaptation algorithm must acquire and track the weights even with rapid fading. The performance of the least-mean-square (LMS) and direct matrix inversion (DMI) algorithms in the digital mobile radio system IS-54 is considered. Results for two base station antennas with flat Rayleigh fading show that the LMS algorithm has large tracking loss for vehicle speeds above 20 mph, and that the DMI algorithm can acquire and track the weights to combat desired-signal fading and suppress interference with close to ideal tracking performance at vehicle speeds up to 60 mph.