Topology control for service-oriented wireless mesh networks - [Service-oriented broadband wireless network architecture]

Topology control is one of the most critical design issues in multihop wireless networks. Topology control has been investigated extensively in the literature. Nevertheless, it is noted that most existing studies do not consider the requirements on upper layer applications or services. In this article we address the topology control issues on service-oriented wireless mesh networks. In particular, we provide a comprehensive survey of existing works on topology control from a service- oriented perspective. We then propose a general framework for topology control in service- oriented WMNs. To demonstrate the effectiveness of the framework, we conduct a case study in which the main objective is to maximize the overall throughput in a network with random unicast traffic. The performance of this topology control scheme is evaluated by numerical results. In addition, it is illustrated that the generated topology can support advanced technologies, including network coding and physical-layer network coding, which can significantly improve the throughput capacity of a network.     

Security in service-oriented vehicular networks - [Service-oriented broadband wireless network architecture]

Service-oriented vehicular networks support diverse infrastructure-based commercial services including Internet access, real-time traffic concerns, video streaming, and content distribution. The success of service delivery in vehicular networks depends on the underlying communication system to enable the user devices to connect to a large number of communicating peers and even to the Internet. This poses many new research challenges, especially in the aspects of security, user privacy, and billing. In this article we first identify the key requirements of authentication, privacy preservation, and billing for service delivery in vehicular networks. We then review the existing industrial and academic efforts on service- oriented vehicular networks. We also point out two security challenges, minimizing vehicleto- infrastructure authentication latency and distributed public key revocation, which are considered among the most challenging design objectives in service-oriented vehicular networks. A novel fast vehicle-to-infrastructure authentication based on a vehicle mobility prediction scheme and an infrastructure-based short-time certificate management scheme are then proposed to address these two challenges.     

Using P2P overlays to provide QoS in service-oriented wireless networks - [Service-oriented broadband wireless network architecture]

An increasing number of applications require some form of guarantees from the network, in terms of bandwidth or access and transfer delay. This demand for quality of service can be met by means of different mechanisms, depending on the networks being traversed, as well as the degree of integration of the services with the communication infrastructure. Whereas end-to-end QoS provision is still an open problem, several possibilities now exist in local environments. The article investigates the capabilities offered by a P2P overlay for distributed bandwidth management in a controlled ad hoc deployment, to support specific requirements in service-oriented wireless networks. The mechanism proposed allows complementing the core functionalities of the IEEE 802.11e protocol, and enhancing them to handle local mobility and dynamic requests for bandwidth. The performance evaluation is provided in an emulated environment to show the effectiveness of the presented approach.     

Service-oriented broadband wireless network architecture - [Guest editorial]

In the past few years, broadband wireless networks have been very attractive as a key technology for providing Internet access because of quick and cost-effective deployments. In addition to the features of high data rate and large coverage, broadband wireless networks also promise to rapidly provide access to locations in the world?s rural and developing areas where broadband is currently unavailable, as well as compete for urban market shares. Till now, most existing efforts have been focused on basic access capability. However, to successfully operate broadband wireless networks, a crucial issue must be addressed: how to support a variety of services and applications within the broadband wireless networks? As an example, there is an increasing need to efficiently support applications such as voice over IP (VoIP), video streaming, music downloading, IP TV, and many others.     

A quality-driven decision engine for live video transmission under service-oriented architecture - [Service-oriented broadband wireless network architecture]

Service-oriented architecture provides a solution to the increasing network complexity due to ever-growing heterogeneous networks. As the most significant component of SOA, the decision engine is to create a workflow, defined as a sequence of individual data processing entities, for providing end-to-end QoS of a given task. Although the workflow of video transmission is generally known, existing solutions are often monolithic. Furthermore, there is no decision engine to select a workflow based on the best user-perceived quality. In this article we propose a service-oriented decision engine framework, which consists of a decision engine, a performance evaluation component, and other major SOA components to support real-time video transmission over wireless multihop networks, aiming to provide the best user-perceived video quality under application-centric QoS constraints. Based on the investigation of the state of- the-art research efforts on SOA, some key issues for wireless live video transmission are discussed, and a case study for live video transmission is given to illustrate the proposed scheme. The superior performance of the proposed service-oriented decision engine is validated by experimental results.     

Dynamic composition of services for end-to-end information transport - [Service-oriented broadband wireless network architecture]

An increasing number of communication technologies in access and core segments of the network belonging to different providers and subject to different network design criteria are making networks complex and difficult to manage. In such networks it is also more difficult to guarantee requested levels of quality of service. Service oriented design can be the answer to problems facing the providers of services for information transport. In this article we propose an end-to-end service composition for information transport based on principles from service oriented architecture (i.e., dynamically composing transport services with characteristics matching the requirements of a given application). SOA principles are similar to those behind the division of labor, and therefore should give providers incentive to adopt them to make better use of resources and increase revenue. As we show, some SOA concepts are similar to concepts in the open systems interconnection reference model, with the key advantages of dynamism and flexibility. We discuss service oriented networks based on transport service composition across access and core segments, and describe access network selection for online gaming. In particular, we show how semantic technologies can be used for layer 2 queries and discuss the advantages of using knowledge bases over traditional approaches.     

Downlink scheduling for multimedia multicast/broadcast over mobile wimax: connection-oriented multistate adaptation - [Service-oriented broadband wireless network architecture]

With its comprehensive QoS support and ubiquitous coverage, the mobile WiMAX network offers promising opportunities for unwiring the last mile connectivity to Internet. However, stringent QoS demands of multimedia applications entail studies on service-oriented radio resource management. This article systematically examines the design issues and the state of the art of multimedia downlink scheduling in the multicast/broadcast-based WiMAX system. We propose a viable end-to-end framework, connection-oriented multistate adaptation, by considering cross-layer adaptations in source coding, queue prioritization, flow queuing, and scheduling. Its performance is confirmed by simulations on important metrics, showing that the framework can effectively accommodate heterogeneity in link variations, queue fluctuations, and reception diversities.     

Viva mesh Vegas [mesh wireless network]

In this paper, the mesh wireless network established by Cheetah Wireless Technologies Inc. is discussed. Cheetah's mobile wireless network is one of the first municipal installations to use mesh wireless technology, which allows users to access the Internet anywhere within the coverage area even if they're driving at 100 kph. Mesh networks have several key advantages over traditional wireless solutions, such as Wi-Fi or cellphones. Benefits include higher speeds, less susceptibility to radio interference, and greater resistance to network congestion. These networks also offer better coverage, the ability to prioritize different types of users, geolocation capabilities, tighter security, faster deployment, and a degree of immunity to catastrophic network failures.     

A genetic approach to joint routing and link scheduling for wireless mesh networks

Wireless mesh networks are an attractive technology for providing broadband connectivity to mobile clients who are just on the edge of wired networks, and also for building self-organized networks in places where wired infrastructures are not available or not deemed to be worth deploying. This paper investigates the joint link scheduling and routing issues involved in the delivery of a given backlog from any node of a wireless mesh network towards a specific node (which acts as a gateway), within a given deadline. Scheduling and routing are assumed to be aware of the physical interference among nodes, which is modeled in the paper by means of a signal-to-interference ratio. Firstly, we present a theoretical model which allows us to formulate the task of deriving joint routing and scheduling as an integer linear programming problem. Secondly, since the problem cannot be dealt with using exact methods, we propose and use a technique based on genetic algorithms. To the best of our knowledge, these algorithms have never been used before for working out these kinds of optimization problems in a wireless mesh environment. We show that our technique is suitable for this purpose as it provides a good trade-off between fast computation and the overall goodness of the solution found. Our experience has in fact shown that genetic algorithms would seem to be quite promising for solving more complex models than the one dealt with in this paper, such as those including multiple flows and multi-radio multi-channels.     

Oblivious routing in wireless mesh networks

As new network applications have arisen rapidly in recent years, it is becoming more difficult to predict the exact traffic pattern of a network. In consequence, a routing scheme based on a single traffic demand matrix often leads to a poor performance. Oblivious routing (Racke in Proceedings of the 43rd annual IEEE symposium on foundations of computer science 43–52, 2002) is a technique for tackling the traffic demand uncertainty problem. A routing scheme derived from this principle intends to achieve a predicable performance for a set of traffic matrixes. Oblivious routing can certainly be an effective tool to handle traffic demand uncertainty in a wireless mesh network (WMN). However, a WMN has an additional tool that a wireline network does not have: dynamic bandwidth allocation. A router in a WMN can dynamically assign bandwidth to its attached links. This capability has never been exploited previously in works on oblivious routing for a spatial time division multiple access (STDMA) based WMN. Another useful insight is that although it is impossible to know the exact traffic matrix, it is relatively easy to estimate the amount of the traffic routed through a link when the routing scheme is given. Based on these two insights, we propose a new oblivious routing framework for STDMA WMNs. Both analytical models and simulation results are presented in this paper to prove that the performance—in terms of throughput, queue lengths, and fairness—of the proposed scheme can achieve significant gains over conventional oblivious routing schemes for STDMA based WMNs.     

Joint multi-radio multi-channel assignment, scheduling, and routing in wireless mesh networks

The IEEE 802.11 DCF and EDCA mechanisms based on CSMA/CA are the most widely used random channel access mechanisms in wireless mesh networks (WMNs), but unfortunately these cannot effectively eliminate hidden terminal and exposed terminal problems in multi-hop scenarios. In this paper, we propose a set of efficient multi-radio multi-channel (MRMC) assignment, scheduling and routing protocols based on Latin squares for WMNs with MRMC communication capabilities, called “M4”, i.e., the Multiple access scheduling in Multi-radio Multi-channel Mesh networking. M4 uses nodal interference information to form cliques for inter-cluster and intra-cluster inWMNs, and then applies Latin squares to map the clique-based clustering structure to radios and channels for communication purposes. Then, M4 again applies Latin squares to schedule the channel access among nodes within each cluster in a collision-free manner. From a systematic view, we also design the corresponding MRMC routing to support M4 communication. Extensive simulation results show that M4 achieves much better performance than IEEE 802.11 standards and other channel access control protocols.     

Domain load balancing routing for multi-gateway wireless mesh networks

As Wireless Mesh Networks (WMNs) are typically used for Internet access, most traffic is routed through the gateways which connect WMN to the wired network. As a result, the gateways tend to get congested and balancing of the traffic load of gateways is critical. In this paper, we consider applications that require continuous provision of a certain bandwidth to a server located at the wired network. If a path that satisfies the bandwidth request cannot be found, the request will be rejected, so that load imbalance will result underutilization of the network capacity. We present a novel load balancing routing algorithm for maximizing the network utilization (i.e., accommodating service requests as many as possible) for multi-gateway WMNs. In the proposed scheme, a WMN is divided into domains. Each domain is served by one gateway, so that all traffic of a domain is served by the corresponding gateway. Our scheme determines routing to balance the traffic load among domains, and then performs load balancing routing within each domain. Simulation results show that in square grid topologies, our intra-domain routing achieves near optimal performance with about 70% less overhead than the existing schemes. Our inter-domain load balancing scheme outperforms the existing heuristics by up to 25% while achieving about 80% performance of the optimal solution.     

Non-repudiable authentication and billing architecture for wireless mesh networks

Wireless mesh networks (WMNs) are a kind of wireless ad hoc networks that are multi-hop where packets are forwarded from source to destination by intermediate notes as well as routers that form a kind of network infrastructure backbone. We investigate the security of the recently proposed first known secure authentication and billing architecture for WMNs which eliminates the need for bilateral roaming agreements and that for traditional home-foreign domains. We show that this architecture does not securely provide incontestable billing contrary to designer claims and furthermore it does not achieve entity authentication. We then present an enhanced scheme that achieves entity authentication and nonrepudiable billing.     

Improved heuristics for multicast routing in wireless mesh networks

Multicast is a communication technique that allows a source to transmit data to a set of recipients in an efficient manner. Therefore, the primary objective of a multicast routing protocol would be to minimize number of transmissions to conserve bandwidth. The problem of computing multicast trees with minimal bandwidth consumption is similar to Steiner tree problem and has shown to be NP-complete. So, heuristic based algorithms are suitable to approximate such bandwidth optimal trees. This paper proposes a multicast routing protocol based on minimum number of transmission trees using an heuristic approach. The simulation results show that the proposed algorithm offers better performance over existing protocols, even in the worst-case scenario when the set of multicast receivers are sparsely distributed across the network.     

A fast and reliable routing technique for wireless mesh networks

In wireless mesh networks (WMNs), real time communications (e.g., Voice over IP (VoIP) and interactive video communications) may often be interrupted as packets are frequently lost or delayed excessively. This usually happens due to the unreliability of wireless links or buffer overflows along the routing paths. The mesh connectivity within the WMN enables the capability to enhance reliability and reduce delay for such applications by using multiple paths for routing their packets. The vital components in multi‐path routing for achieving this are the pre‐determined formation of paths and the technique that the paths are deployed for packet traversal. Therefore, we propose a novel multi‐path routing protocol by introducing a new multi‐path organization and a traffic assignment technique. The designed technique dubbed as FLASH (Fast and reLiAble meSH routing protocol) discovers one primary path between a pair of source and destination based on a new proposed metric, and thereafter selects mini‐paths, which connect pairs of intermediate nodes along the primary path. The primary path and mini‐paths are concurrently deployed, as multiple copies of packets are routed through. This technique compensates for possible outage at intermediate wireless nodes or their corresponding wireless links along the primary path. Routing along mini‐paths is performed in such a way that redundant copies do not cause an excessive congestion on the network. The effectiveness of the proposed scheme is evaluated analytically and through extensive simulations under various load conditions. The results demonstrate the superiority of the proposed multi‐path organization in terms of reliability and satisfactory achievements of the protocol in enhancing delay and throughput compared to the existing routing protocols, especially for long distances and in congested conditions. Copyright © 2010 John Wiley & Sons, Ltd.