Study On Multidimensional Spectrum Reuse Method In Wireless Regional Area Network

In recent years, there has been an increasing growth in wireless services, yielding a huge demand on the radio spectrum. In order to efficiently exploit these spectrum holes, cognitive radio (CR) has been proposed. WRAN is the first international standard based on cognitive radio technology is IEEE802.22, which is designed to operate in the TV broadcast bands while ensuring that no harmful interference is caused to the incumbent operation (digital TV and analog TV broadcasting) and low-power licensed devices such as wireless microphones.(1) This paper gives a comprehensive description about the significance of the research, introduces the spectrum sensing and spectrum sharing technology in the wireless local area network and the current status of the multidimensional spectrum reuse method in the WRAN is summarized.(2) The method of using multiple transmission dimensions such as time, frequency and antenna directionality to improve the system utility in WRAN has been analyzed without considering the interference between second users and primary users.(3) We propose an accurate and realistic downlink coexistence model when considering coexistence between second users and primary users. Based on graph theory the joint spatial domain and frequency domain spectrum reuse method of downlink has been proposed. To solve the problem while reducing the computational cost significantly we employ Hungarian algorithm. Theoretical analysis and simulation results indicate that the ratio of bandwidth and the spectrum holes’ utilization in spatial domain and frequency domain can be availably increased by the antenna pre-coding technique and the sub-channels division technique.(4) Considering the existing uplink coexistence model did not take advantage of the spatial spectrum holes we develop an accurate and realistic uplink coexistence model. Based on the proposed model, an uplink joint spatial domain and frequency domain spectrum reuse method has been proposed. To reduce the computational cost we can model the problem of joint channel and weight vector of antenna allocation as a potential game. Theoretical analysis and simulation results indicate that the ratio of bandwidth and the spectrum holes utilization both in spatial domain and frequency domain can be availably increased by using directional antennas and the sub-channels division technique.