Bandwidth-guaranteed multicast in multi-channel multi-interface wireless mesh networks

Proceedings of the IEEE International Conference on Communications, 2009, p. 1-5We consider multi-channel multi-interface wireless mesh networks with a schedule-based MAC protocol, where conflict-free transmission is ensured by requiring links assigned with the same channel and within the mutual interference range of each other to be active at different time slots. When a (point-to-multipoint) multicast call arrives, the call is accepted if a multicast distribution tree can be established for connecting the source node with all the receiving nodes, and with sufficient bandwidth reserved on each link. Otherwise, the call is rejected. To maximize the call acceptance rate, the multicast tree must be constructed judiciously upon each call arrival. Aiming at minimizing the carried load on the most-heavily loaded channel, and maximizing the residual capacity of the most heavily loaded node, an integer linear program (ILP) is formulated for multicast tree construction. Since solving ILP can be time-consuming, an efficient heuristic algorithm is then proposed. We compare the two tree construction algorithms by simulations. We found that both algorithms give comparable call acceptance rate, but the heuristic algorithm requires much shorter running time. ©2009 IEEE.published_or_final_versio

Maximizing multicast call acceptance rate in multi-channel multi-interface wireless mesh networks

In this paper, we consider the problem of constructing bandwidth-guaranteed multicast tree in multi-channel multi-interface wireless mesh networks. We focus on the scenario of dynamic multicast call arrival, where each call has a specific bandwidth requirement. A call is accepted if a multicast tree with sufficient bandwidth on each link can be constructed. Intuitively, if the carried load on both the most-heavily loaded channel and the most-heavily loaded node is minimized, the traffic load in the network will be balanced. If the network load is balanced, more room will be available for accommodating future calls. This would maximize the call acceptance rate in the network. With the above notion of load balancing in mind, an Integer Linear Programming (ILP) formulation is formulated for constructing bandwidth-guaranteed tree. We show that the above problem is NP-hard, and an efficient heuristic algorithm called Largest Coverage Shortest-Path First (LC-SPF) is devised. Simulation results show that LC-SPF yields comparable call acceptance rate as the ILP formulation, but with much shorter running time. © 2010 IEEE.published_or_final_versio

Cross-layer schemes for performance optimization in wireless networks

Wireless networks are undergoing rapid progress and inspiring numerous applications. As the application of wireless networks becomes broader, they are expected to not only provide ubiquitous connectivity, but also support end users with certain service guarantees. End-to-end delay is an important Quality of Service (QoS) metric in multihop wireless networks. This dissertation addresses how to minimize end-to-end delay through joint optimization of network layer routing and link layer scheduling. Two cross-layer schemes, a loosely coupled cross-layer scheme and a tightly coupled cross-layer scheme, are proposed. The two cross-layer schemes involve interference modeling in multihop wireless networks with omnidirectional antenna. In addition, based on the interference model, multicast schedules are optimized to minimize the total end-to-end delay. Throughput is another important QoS metric in wireless networks. This dissertation addresses how to leverage the spatial multiplexing function of MIMO links to improve wireless network throughput. Wireless interference modeling of a half-duplex MIMO node is presented. Based on the interference model, routing, spatial multiplexing, and scheduling are jointly considered in one optimization model. The throughput optimization problem is first addressed in constant bit rate networks and then in variable bit rate networks. In a variable data rate network, transmitters can use adaptive coding and modulation schemes to change their data rates so that the data rates are supported by the Signal to Noise and Interference Ratio (SINR). The problem of achieving maximum throughput in a millimeter-wave wireless personal area network is studied --Abstract, page iv

Mobility-adaptive clustering and network-layer multicasting in mobile ad hoc networks

Ph.DDOCTOR OF PHILOSOPH

Localized Minimum Spanning Tree Based Multicast Routing with Energy-Efficient Guaranteed Delivery in Ad Hoc and Sensor Networks

We present a minimum spanning tree based energy aware multicast protocol (MSTEAM), which is a localized geographic multicast routing scheme designed for ad hoc and sensor networks. It uses locally-built minimum spanning trees (MST) as an efficient approximation of the optimal multicasting backbone. Using a MST is highly relevant in the context of dynamic wireless networks since its computation has a low time complexity (O(n log n)). Moreover, our protocol is fully localized and requires nodes to gather information only on 1-hop neighbors, which is common assumption in existing work. In MSTEAM, a message split occurs when the MST over the current node and the set of destinations has multiple edges originated at the current node. Destinations spanned by each of these edges are grouped together, and for each of these subsets the best neighbor is selected as the next hop. This selection is based on a cost over progress metric, where the progress is approximated by subtracting the weight of the MST over a given neighbor and the subset of destinations to the weight of the MST over the current node and the subset of destinations. Since such greedy localized scheme may lead the message to a void area (i.e., there is no neighbor providing positive progress toward the destinations), we also propose a completely new multicast generalization of the well-know face recovery mechanism. We provide a theoretical analysis proving that MSTEAM is loop-free and always achieves delivery of the multicast message, as long as a path exists between the source node and the destinations. Our experimental results demonstrate that MSTEAM is highly energy-efficient, outperforms the best existing localized multicast scheme and is almost as efficient as a centralized scheme in high densities

Performance Evaluation of Multicast Trees in Adhoc Networks

An adhoc wireless network is a network composed of mobile hosts with no fixed infrastructure and no central administration. The main constraints in these networks are bandwidth limitation and unpredictable hosts mobility. In this context, one challenge is to propose multi-hop routes for multicast routing protocols. In this paper, we present a set of criteria adapted to the evaluation of multicast diffusion structures in adhoc networks. We also use these criteria to evaluate different tree construction algorithms and propose several comments for the design of an efficient multicast routing protocol