Application of Adaptive Array Processing to Cellular Base Station Antennas

Since expansion of wireless networks is limited to scarce spectrum resources, methods are needed that support increased capacity (number of users), while conserving spectrum. In this proposal we suggest space-time methods and algorithms capable of providing significant capacity increases for both CDMA and TDMA, as well as improving performance of CMDA in overlay situations. Specifically, we propose several space-time receiver configurations and a novel adaptive eigencancaler algorithms, as approaches that directly increase users per cell in CDMA and improve the frequency reuse of current TDMA systems. The Phase I goal is to prove feasibility in a realistic time-varying multipath cellular wireless channel. The phase II product will be a real-time COTS multiple-signal processor, programmed to combine and process signals from several antennas, to optimize each desired user's signal (e.g., minimum BER) while suppressing power from competing users. It is shown that diversity processing and interference cancellation in adaptive arrays provide significant capacity increases with just a few antenna elements and hence at low-cost and with only modest through put requirements. Analysis and preliminary results are provided to support the soundness and utility of the proposed methods.