Research On Resource Allocation And Scheduling In Wireless Broadband Networks

Growing wireless broadband access technologies have brought great convenience and changes to our work and life during recent years. There are different wireless technologies coexisting for different purposes and applications, and they will make a ubiquitous coverage with the wired broadband networks over the world in the near future. Due to the scarce wireless frequency resources, how to improve the efficiency of wireless resource allocation to satisfy increasing wireless applications has been the research interest. In this work, we focus on the radio resource management and scheduling algorithms in broandband wireless networks, such as wireless mesh networks and OFDMA-based networks, and we propose several algorithms on MAC layer channel assignment, joint resource scheduling and error-resilient video multicast to fully utilize wireless radio resources.In this work, we study a link-weighted and distance-constrained channel assignment problem in multi-channel wireless mesh networks. We introduce an interference metric, namely, Min-Max I-value of an edge (MMIE), to explicitly account for interference among links that are at distance one. In addition, we further show that the link-weighted and distance-constrained channel assignment problem with respect to the interference metric MMIE is NP-hard in computation. This guides us to develop a centralized link-weighted and distance-constrained channel assignment. To further apply the algorithm into wireless networks with large-number nodes and dynamic channel conditions, we propose distributed link-weighted and distance-constrained channel assignment. We study the performance of our algorithms by implementing it in a wireless simulation environment. The NS2.33 simulation results show that in a multi-channel environment, both two algorithms significantly outperform other three well-known schemes. Furthermore, the performance of the distributed algorithm using local network profile is very close to the centralized one.With the increasing popularity of multicast and real-time streaming service applications, efficient channel assignment algorithms that handle both multicast and unicast traffic in wireless mesh networks are needed. In this work, we combine unicast and multicast with a transmission set, and propose a framework named chordal graph based channel assignment that performs channel assignment for multicast and unicast traffic in multi-channel multi-radio wireless mesh networks. The proposed framework based on chordal graph coloring minimizes the interference of the network and prevents unicast traffic from starvation. Simulation results show that our framework provides high throughput and low end-to-end delay for both multicast and unicast traffic. Furthermore, our framework significantly outperforms other well-known schemes that have a similar object in various scenarios.There exist dependencies among wireless channel, scheduling and routing problem. Hence, it is better to jointly consider these problems. In this work, we develop fully distributed algorithms that jointly solve the channel-assignment, scheduling and routing problem for multichannel multiradio wireless mesh networks. The algorithms that we developed are amenable to distributed implementations. They do not require prior information on the offered load to the network, and can thus adapt automatically to the changes in the network topology and offered load. We show that these algorithms are provably efficient. That is, even compared with the optimal centralized and offline algorithm, our proposed algorithms can achieve a provable fraction of the maximum system capacity.Video multicast over broadband wireless networks suffers packet losses induced by fading wireless channels and user heterogeneity in channel conditions within a multicast group. A promising solution to these problems is the use of layered hybrid FEC/ARQ for scalable video multicast. However, how to allocate the radio resources to multiple video layers and how to address the cross-layer combination of application layer hybrid FEC/ARQ and physical layer MCS (modulation and coding schemes) for each video layer, is not a trivial issue. We prove that this problem is NP-hard and propose an error-resilient video multicast framework in infrastructure-based broadband networks. To combat the packet loss, we use the layered hybrid FEC/ARQ scheme, which provides unequal error protection for each video layer. To avoid user heterogeneity and feedback implosion, we use a designated user group to send light-weight feedback messages. Simulation results show that our algorithm offers significant improvements over other related schemes.