Studies On Radio Resource Management With Cross-Layer Design And Open Spectrum

With the developmet of telecommunication technology and the popularity of Internet, wireless networks, as an important part of the Next Generation Networks (NGNs) attract increasing attention in both industry and academy. Wireless networks are expected to provide wider bandwidth, higher transmission rate as well as strict Quality of Service (QoS) guarantee. However, the inherent transmission traits of physical layer in wireless networks, limit radio resources as well as requirments on broadband have brought new challenges in Radio Resource Management (RRM) researches. RRM researches will be significant for improving network performance. In this thesis, we focus on dynamic scheduling and radio resource allocation in RRM with cross-layer design and open spectrum respectively, based on radio spectrum static regulation and dynamic one. The main contributions of our work are as follows:1. We proposed modified cross-layer scheme combined with Adaptive Modulation and Coding (AMC) and Selective Repeat Automatic Repeat Request (SR-ARQ) in wireless networks. We also proposed N-Succeed/N+1-Failed throughput model on which the theoretical analysis is based. The existed rate adaptive scheme with channel prediction techniques is employed in the modified cross-layer scheme. Hence, the modified scheme considered the traits of time-varying channels rather than uses channel state of current frame when choosing the modulation mode for the next fame. And it does improve QoS. The performance of modified scheme is analyzed comparing with that of existing schemes by a large mount of simulation works. The simulation results show that the modified scheme outperforms the existing one in Packet Error Rate (PER) and improve spectrum efficiency.2. We proposed a cross-layer algorithm, RTCLA, for real-time (RT) applications traversing both wired links and wireless links, based on the above cross-layer scheme. The proposed algorithm, RTCLA, considers both system throughput and users' strict end-to-end QoS requirements for such RT applications traversing heterogeneous networks. We analyze the performance of the proposed algorithm comparing with those of three classic scheduling algorithms, Modified Proportional Fair Algorithm, Earliest Deadline First (EDF) Algorithm, and Modified Largest Weighted Delay First (M-LWDF) algorithm, in packet time-out rate, system average throughput and fairness. The simulation results show that RTCLA is more appropriate for delay sensitive applications than other algorithms considering strict delay requirements and time-varying channels. Especially, RTCLA outperforms both MPF and M-LWDF algorithms in packet time-out rate.3. We proposed a cross-layer frequency-time scheduling and resource allocation algorithm for downlink in OFDMA systems. In the proposed algorithm, we considered some QoS parameters such as channel state, users' rate requirments on MAC layer, delay requirements, PER requirements, and aimed at improving spectrum utilization as well as fairness. Then, we compared performance of the proposed algorithm with that of PF and M-LWDF algorithms. The simulation results show that our algorithm ourperforms others both in system spectrum utilization and outage.4. We studied dynamic spectrum allocation in open spectrum system, and graphic theory was employed to formulate the problem. Then, we analyzed the problem based on the system models. Considering system sum bandwidth, convergency and fairness, we proposed two heuristic algorithms, Fast Convergent algorithm with Max-sum-Bandwidth (FCMB) and Heuristic Fair With max-sum-Bandwidth algorithm, for different scenario. The performance of these two algorithms were studied and compared with existing ones by simulations. Additionally, we also studied the influences of environment factors by simulations.