Development of Adaptive Array Antenna for Mobile WiMAX Uplink

Mobile worldwide interoperability for microwave access (Mobile WiMAX) based on IEEE 802.16e is a standard designed for metropolitan area networks (MAN) that cover an area wider than that covered by local area networks. Commercial WiMAX services are already available in some countries and regions. Services in Japan are scheduled to start in 2009. Mobile WiMAX supports “one-cell frequency reuse,” which allows adjacent cells to use the same frequency. This causes co-channel interference to occur, resulting into degradation of communication quality. It is therefore necessary to cancel interference from other cells to ensure high communication quality. Adaptive array antenna is an effective means of removing interference waves; however, it is difficult to apply the conventional algorithm to the frame configuration in Mobile WiMAX systems. The authors therefore developed an adaptive array that is optimized for use in Mobile WiMAX uplink. This paper presents the summaries of WiMAX and adaptive array antenna, and describes the algorithm for the newly-developed adaptive array antenna. The results for the simulation tests and experimental tests performed using prototype base stations are also presented at the end of this paper.