Adaptive Space-Time Sectorization for Interference Reduction in Smart Antenna Enhanced Cellular WiMAX Networks

Adaptive antennas are currently being integrated into wireless systems. As one of the first standards the wireless metropolitan area network IEEE 802.16 provides means to support smart antenna techniques. By means of adaptive antenna patterns smart antennas allow steering the transmit/receive power into certain directions while suppressing undesired power, i.e. interference. This paper introduces an adaptive space-time sectorization scheme that reduces interference by grouping subscriber stations into space-time sectors. The realization of space-time sectors is achieved only by reorganizing transmit and receive bursts within the MAC frame. The proposed scheme results in the same interference reduction as conventional sectorization, but it avoids major disadvantages. Additionally, the sectorization scheme offers various benefits being combined with SDMA. Finally, a MAC frame structure has been designed to allow for space-time sectorization. The frame design is standard compliant to the promising radio access technology IEEE 802.16.