New beam-forming algorithm controlling pattern of multiple smart antennas for cellular systems

Abstract

The popularity of mobile communications has pushed the demand for channel capacity ever higher. However, frequency resources are limited and most frequencies in the microwave band, which are suited to mobile communications, have already been assigned to various radio systems. Thus, frequency reuse is now one of the most important issues facing future wireless communication systems. Smart antennas have been receiving much attention with respect to this issue because base stations employing these antennas can effectively suppress co-channel interference by controlling the beam pattern and reducing the distance between the cells using the same channel. Generally, each smart antenna base station controls its beam pattern independently. However, the reduction in distance is limited when using this independent pattern control scheme. We propose a new beam-forming algorithm as a solution for actualizing the pattern control of multiple smart-antenna base stations in an actual cellular system. This paper first describes the problem that an ordinary smart antenna base station is faced with when the distance between the base stations becomes short. Then the proposed new beam-forming algorithm is described. Finally, the effectiveness of the proposed algorithm is evaluated by computer simulation.