Research On Resource Allocation And Frequency Reuse In OFDMA Cellular Relay Networks

The next generation mobile communication networks need to enable ubiquitous high-speed coverage to meet the growing communication requirements. To achieve this goal must efficiently use the limited scarce spectrum resources. The combination of orthogonal frequency division multiple access (OFDMA) technology and the relay technology will be used in the next generation wireless communication networks. OFDMA is adopted by the next generation networks due to its inherent ability to combat frequency selective fading, and it also provides greater flexibility in the radio resource allocation scheme to exploit more potential system performance. On the other hand, the relay technology can improve the channel conditions to increase the system throughput, especially for the edge users. Therefore, the combination of the two technologies will provide a high performance communications network.In order to improve the system spectrum efficiency, intelligent resource management scheme and frequency reuse scheme can be introduced to using the system resources efficiently and aggressively. So this article mainly researches on the radio resource management technologies and frequency reuse scheme in OFDMA cellular relay networks. Firstly, we propose a efficient radio resource allocation scheme, which joint sub-carrier scheduling and routing to adaptively allocates the system resources based on the utility function. The scheme considers both the fairness among users and the delay requirements of real-time users, and introduces their measure factors into the utility function to guide the allocation of subcarriers. And ultimately make the system get an efficient tradeoff among throughput, fairness and real-time user delay requirements.Secondly, we propose a new dynamic full frequency reuse scheme to guide the base station and relay to adaptively reuse based on the system channel conditions to get more diversity and multiplexing gain, which allow the base station reusing all the subcarriers in the whole BS coverage region to exploit more multiuser diversity gain. In addition, the adaptive subcarrier scheduling scheme is introduce to adaptively allocate the subcarrier resources, where each subcarrier selects a pair of base station and relay with the highest system performance to sharing. So that all subcarriers are best used and system performance will also be the highest.Thirdly, based on the proposed dynamic frequency reuse, we introduce the opportunistic frequency reuse scheme, which intelligently allocates the subcarriers originally reused by the base station and a relay to another relay as long as it can best improve the system performance after considering the additional interference. So the subcarriers will be adaptively reused between the relays in order to further improve the system spectral efficiency.Finally, based on the directional antenna technology, we propose two high spectral efficiency frequency reuse schemes with frequency reuse factor of nine. In order to reduce interference in the cell because of the high frequency reuse factor, each relay or base station service area is divided into the inner zone and outer zone and different transmit power are assigned to the two zones to improve the user channel conditions to reduce the outage probability of the system. Also we reasonably distribute the transmit power of base station and relays to further reduce the interference level.