BROAD-BAND SPACE DIVERSITY FOR DIGITAL MICROWAVE RADIO SYSTEMS

A new broadband space diversity (B-SD) combining method, which is a ke y technique in the growth of digital microwave radio system, is propos ed. In this B-SD combining method, two received signals, whose bandwid ths are 280 MHz. are combined. To develop this combining method, an op timum control algorithm is developed that monitors power levels of all primary carriers and controls the endless phase shifter so that the h igher level signal is decreased and the lower level signal is increase d. This paper describes the proposed B-SD combining method which effec tively operates over a wide bandwidth. Performance evaluations based o n simulations and theoretical estimations are given. It is proven that this combining method offers the same performance obtained by the con ventional narrowband SD combining method and fan be applied to over 50 % cases af the propagation paths observed in Japan. The suitability of the proposed combining method and the calculation methods adopted is demonstrated experimentally.