On Path Selection Algorithm For OFDMA Multi-Hop Relay Cellular Networks

As the society develops and communication technology advances, the wireless access networks have demonstrated a trend toward higher capacity and more diversified services. Traditional cellular network can not meet this demand, so Multi-hop Relay Cellular Network (MRCN) which uses Orthogonal Frequency Division Multiple Access (OFDMA) technology in its physical layer is widely concerned by its high data rate and extensive coverage advantage. The network structure becomes complicated because of Relay Station (RS), therefore, the path selection in MRCN as a new hot issue has been raised. Combined the two-dimensional time-frequency features of allocated resources with the QoS features of Subscriber Station (SS), this thesis focuses on path selection algorithms in MRCN.In the second chapter, this thesis introduces several related technologies in MRCN, including networking mode and frame structure. On this basis, the analysis of the system capacity is given. A system simulation platform is built for MRCN by modular method. In the third chapter, compared with three typical path selection algorithms, which use distance, path loss and SINR (Signal Interference and Noise Ratio) as the metric, and combined with the features of resource allocation, a path selection algorithm which uses occupied slot number as metric is analyzed and evaluated. On this basis, this thesis brings forward an improved occupied slot number path selection algorithm in the fourth chapter. Considering different QoS features of multi-service, we establish a QoS parameter evaluation feedback system and introduce comprehensive evaluation factor of station to track the load and service quality of station timely. The simulation results show that the system can achieve a more optimized overall performance.In traditional cellular networks, no matter how far the distance of Base Station (BS) and SS, the communication between the two stations must be forwarded through the BS's air interface. This transfer mode makes BS's air interface become a bottleneck for further enhancing system capacity. Considering the characteristic of PMP tree network mode of MRCN and the flow of service in hot spots with high density and low mobility relatively such as communities, schools and enterprises and so on, this thesis tries to give an enforceable signaling scheme of shortcut technology in the fifth chapter. On this basis, a path selection algorithm based on shortcut mode is put forwarded, Further simulation analysis shows that in the case of small signaling overload, shortcut transmission mode can effectively improve system performance and alleviate the pressure of BS air interface.