Multi-radio Multi-channel Wireless Research Articles

Delay constraint energy efficient broadcasting in heterogeneous MRMC wireless networks

Energy efficient broadcasting is a critical problem in Multi-Radio Multi-Channel (MRMC) wireless networks and has captured tremendous attention in the past decades. Most existing works try to minimize energy consumption in broadcast by simply minimizing the number of transmissions. However, radios and channels in MRMC wireless networks may have different propagation characteristics, e.g., communication range and energy consumption. Since wireless radios with different communication ranges have different energy consumptions, it is not always true that minimizing the number of transmissions can minimize the energy consumption. Meanwhile, more and more applications require end-to-end delay guarantee to provide Quality of Service (QoS), e.g., wireless video and online games. It is essential to satisfy the delay constraint when broadcasting in MRMC wireless networks as well.In this paper, we investigate the Delay Constraint Minimum Energy Broadcasting (DCMEB) problem in heterogeneous MRMC wireless networks. Especially, we consider heterogeneous radios and channels with different communication ranges and energy consumptions. We present an Energy Efficient Broadcasting (EEB) strategy in this work. EEB utilizes Multi-Dimension Conflict Graph (MDCG) to capture the conflicts among all possible forwarding nodes and channels, and then calculates the schedule to maximize the number of concurrent transmissions in each time slot in a cost effective way without violating the delay constraint. Our evaluation results show that EEB outperforms the state-of-the-art methods in terms of broadcasting energy cost under delay constraint in heterogeneous MRMC networks.

Distributed Scheduling and Delay-Aware Routing in Multihop MR-MC Wireless Networks

In multiradio multichannel (MR-MC) networks with significantly expanded network resource space, many existing scheduling/routing algorithms rely on a link-based network model and apply different heuristics in algorithm design to achieve/approximate throughput optimality. In this paper, using a tuple-based multidimensional conflict graph model, we establish a cross-layer framework, which facilitates systematically studying distributed scheduling and routing in multihop multipath MR-MC networks. In this framework, each tuple link is installed with a routing controller, which feeds controlled amounts of data to the tuple-link output queues for scheduling and transmission. We rigorously prove that, under a set of certain conditions, the network is queue stable in the mean sense under the distributed maximal scheduling policy. Based on Lyapunov optimization, we further propose a distributed delay-aware multipath routing method, which aims at minimizing the end-to-end delay of each commodity flow. Extensive simulation results demonstrate that the proposed joint scheduling/routing algorithm outperforms existing link-based single-path and multipath algorithms and tuple-based cross-layer control algorithm.

A Systematic Study of Maximal Scheduling Algorithms in Multiradio Multichannel Wireless Networks

The greedy maximal scheduling (GMS) and maximal scheduling (MS) algorithms are well-known low-complexity scheduling policies with guaranteed capacity region in the context of single-radio single-channel (SR-SC) wireless networks. However, how to design maximal scheduling algorithms for multiradio multichannel (MR-MC) wireless networks and the associated capacity analysis are not well understood yet. In this paper, we develop a new model by transforming an MR-MC network node to multiple node-radio-channel (NRC) tuples. Such a framework facilitates the derivation of a tuple-based back-pressure algorithm for throughput-optimal control in MR-MC wireless networks and enables the tuple-based GMS and MS scheduling as low-complexity approximation algorithms with guaranteed performance. An important existing work on GMS and MS for MR-MC networks is that of Lin and Rasool (IEEE/ACM Trans. Networking, vol. 17, no. 6, 1874--1887, Dec. 2009), where link-based algorithms are developed. Compared to the link-based algorithms, the tuple-based modeling has significant advantages in enabling a fully decomposable cross-layer control framework. Another theoretical contribution in this paper is that we, for the first time, extend the local-pooling factor analysis to study the capacity efficiency ratio of the tuple-based GMS in MR-MC networks and obtain a lower bound that is much tighter than those known in the literature. Moreover, we analyze the communications and computation overhead in implementing the distributed MS algorithm and present simulation results to demonstrate the performance of the tuple-based maximal scheduling algorithms.

A Wireless Mesh Network Channel Assignment Method Based on Potential Game

To solve multi-radio multichannel (MRMC) wireless Mesh network channel assignment problems, we propose and study the PGCA (channel assignment based on potential game) method. PGCA takes each link of the network as a player by designing rational potential function. The action strategies between links select resources containing channel and space information. PGCA converts maximum network throughput into minimum network interference by joint game. Simulation results show PGCA algorithm has better performance in terms of convergence speed and the network throughput. The end-to-end delay has connected with the number of links.

Routing Metrics for Minimizing End-to-End Delay in Multiradio Multichannel Wireless Networks

This paper studies how to select a path with the minimum expected end-to-end delay (EED) in a multiradio multichannel (MR-MC) wireless mesh network. While the existing studies mainly focus on the packet transmission delay due to medium access control (MAC), our new EED metric further takes into account the queuing delay at the MAC layer. In particular, in the MR-MC context, we develop a generic iterative approach to compute the multiradio achievable bandwidth (MRAB) for a path, taking the impact of inter-/intraflow interference and space/channel diversity into consideration. The MRAB is then combined with the EED to form the metric weighted end-to-end delay (WEED). As a byproduct of MRAB, a channel diversity coefficient is defined to quantitatively represent the channel diversity for a given path. Moreover, we design and implement a distributed WEED-based routing protocol for MR-MC wireless networks by extending the well-known AODV protocol. Extensive simulation results are presented to demonstrate the performance of EED/WEED-based routing, with comparison to some existing well-known routing metrics.

A theoretical framework for optimal cooperative networking in multiradio multichannel wireless networks

A wide range of next generation wireless networks are based on the multiradio multichannel (MR-MC) network model. A full exploration of the MR-MC wireless network capacity incurs challenging cooperative networking issues including transmission cooperation, resource allocation cooperation, and cross-layer protocol cooperation. In this article, rather than focus on protocol designs for specific cooperative networking issues, we present a generic theoretical framework that could guide the protocol or algorithm development to approach the maximum network capacity. Based on our multidimensional conflict graph (MDCG) tool, we could achieve a cross-layer linear programming framework to study the optimal cooperative networking in two complementary aspects: optimal network dimensioning and throughput-optimal control. While certain NP-hard computing issues hindered the MR-MC network optimization for a long time, the MDCG-based framework can readily generate simple polynomial and distributed algorithms with guaranteed capacity region.

Performance Comparison for Routing Protocols in Multi-Radio Multi-Channel Multi-Hop Wireless Networks

In this paper, we consider a TDMA-based wireless network and address two major issues, fading and interference, existing in wireless networks since fading will lead to low quality links and interference may lead to unfair channel allocation. Because channel allocation selects the proper channel for each logical link and routing determines through which logical links the packets should be forwarded, there is strong interaction between MAC layer and network layer. In this paper, we seek for the performance trend with more channels allocated and further compare the performances of Bellman-Ford and AODV routing protocols based on the Packet Deliver Rate (PDR) to MAC layer in multi-radio multi-channel multi-hop wireless networks. Numerical results are given and discussions as well as insights into performance aspects for multi-radio multi-channel deployment are provided.

Channel Assignment Strategy for Multi-radio Virtual Hierarchical Wireless Mesh Networks

A virtual hierarchical wireless mesh network architecture is studied in this paper, which gains fine user diversity and routing stability. As each node inside a cell is equipped with multiple radios and multiple channels are available, an efficient channel assignment algorithm based on this multi-radio multi-channel virtual hierarchical wireless mesh network is proposed, which combines the channel pre-allocation algorithm with the time-slot multi-graph decomposition algorithm, so as to increase channel resource utilization and ensure the fairness of channel allocation. In the channel preallocation algorithm, a generalized set T-coloring model based on graph theory is utilized. Then, the time-slot multi-graph decomposition algorithm is conducted according to the channel pre-assignment, which exploits spatial reuse features of a multi-channel multi-radio system to optimize the network performance. The algorithm analysis and simulation results show that the proposed channel assignment strategy can improve the network performance effectively with lower complexity and achieve higher channel utilization.