Adaptive beamforming in CDPD mobile end systems

This paper addresses the application of antenna diversity in the Cellular Digital Packet Data (CDPD) Mobile End Systems (M-ESs) as a means to improve the performance of the CDPD forward channel and meet the tight requirements for mobile Internet access. The focal point is the construction of a maximal-ratio digital beamformer, which effectively exploits a periodic signal, transmitted in every CDPD cell. This signal serves as a reference temporal signal and it is used in the adaptive calculation of the complex weights of the beamformer. The paper presents the design and the operation of the adaptive beamformer, it demonstrates its performance through simulation results and additionally it discusses its significance and its applications. It is argued that even for relatively small spacing between the antenna elements the considered beamforming scheme has the potential to provide significant improvements in the performance of the CDPD forward channel.