Protocols For Wireless Mesh Networks Research Articles

DMT Optimal Cooperative MAC Protocols in Wireless Mesh Networks with Minimized Signaling Overhead

In this paper, a cooperative protocol is proposed for wireless mesh networks. Two features are implemented: on-demand cooperation and selection of the best relay. First, cooperation is activated by a destination terminal when it fails in decoding the message from a source terminal. Second, a selection of the best relay is performed when cooperation is needed. The robustness of wireless links are increased while the resource consumption is minimized. The selection of the best relay is performed by a splitting algorithm, ensuring a fast selection process, the duration of which is now fully characterized. Only terminals that improve the direct link participate in the relay selection and inefficient cooperation is avoided. The proposed protocol is demonstrated to achieve an optimal diversity-multiplexing trade-off. This study focuses on Nakagami- wireless channel models to encompass a variety of fading models in the context of wireless mesh networks.

WARF: Component Based Platform for Wireless Mesh Networks

In this paper, we propose a Wireless and Autonomic Routing Framework (WARF), designed for the deployment of a new generation of routing protocols in wireless mesh networks. The framework supports cross-layer operations, multiple radio interfaces, real-time resource monitoring, dynamic resource allocation and multipath adaptive forwarding. WARF nodes are decomposed into four components, contributing to the overall framework behavior: Resource Maintenance, Route Maintenance, Data Forwarding, and Policy Control. The framework is ready for a simultaneous deployment of different routing protocols or their components. It is based on common features found in existing routing protocols. The protocols can be implemented depending on the network topology properties (static, dynamic), usage mode (unicast, broadcast), or other properties (mobility, QoS etc.). Due to the real-time requirements and preference for distributed operations, IPv6 with some extensions is used as a transport mechanism for control data dissemination. In this paper, an example of a WARF implementation on Linux OpenWRT is described, and a message sequence chart of a generic protocol for radio channel management, which uses WARF control messages, is presented.

Link state reasoning based routing protocol for wireless mesh networks

Based on the analysis of the most important challenges in Wireless Mesh Network (WMN),a routing protocol named LR-OLSR was proposed based on the Optimized Link State Routing (OLSR) protocol with cross-layer design theory.The LR-OLSR protocol greatly optimized routing performance by introducing the reasoning method to value the link quality depending on information such as the node load,the packet delivery ratio,and the link availability.The proposed protocol made use of link quality as the routing metric during route selection,and thus could achieve optimal routing and load balancing in WMN.The simulation results on LR-OLSR,OLSR and its typical improvement named P-OLSR and SC-OLSR show that the proposed routing protocol improves the packet delivery ratio,reduces the end-to-end delay,and achieves load balance in the route selection process.

A quality based routing protocol for wireless mesh networks

Wireless mesh networks can provide low-cost solutions for extending the reach of wireless access points by using multi-hop routing over a set of stationary wireless routers. The routing protocol for these networks may need to address quality considerations to meet the requirements of the user. In this paper, we present a quality based routing protocol for wireless mesh networks that tries to maximize the probability of successful transmissions while minimizing the end-to-end delay. The proposed routing protocol uses reactive route discoveries to collect key parameters from candidate routes to estimate the probability of success and delay of data packets transmitted over them. To achieve accurate route quality assessments, a new route quality metric is proposed that uses performance models of data packet transmissions as opposed to estimating route quality from the transmission of control packets, which have different transmission characteristics. These models are developed after careful evaluations of multi-hop wireless transmissions and validated by computer simulations. Relevant parameters that can be used to assess the route quality metric using these models are explained. Extensive performance evaluations of the proposed quality based routing protocol are presented and its benefits in comparison to some other known routing protocols are discussed.

Performance evaluation for on-demand routing protocols based on OPNET modules in wireless mesh networks

In wireless networks, users expect to get access to the network securely and seamlessly to share the data flow of access points anytime and anywhere. However, either point-to-point or point-to-multipoint methods in traditional wireless networks make the network bandwidth decrease rapidly, which cannot meet the requirements of users. Recently, a new wireless broadband access network, wireless mesh networks (WMNs), has emerged. As one of the key technologies in WMNs, wireless routing protocols plays an important role in performance optimization of WMNs. Therefore, in this paper, we address the on-demand routing protocols by focusing on dynamic source routing (DSR) protocol and ad hoc on-demand distance vector (AODV) routing protocol in WMNs. Then, we use the OPNET modules to establish the simulation models of DSR and AODV protocols in WMNs. Simulation and results show that, DSR protocol that is based on the dynamic source routing is not suitable for wireless transmission, while AODV routing protocol that is based on the purpose-driven routing is suitable for wireless transmission with rapid change of network topology.

A Cooperative Channel Assignment protocol for multi-channel multi-rate wireless mesh networks

Wireless mesh networks (WMNs) are considered as one of the outstanding technologies that provide cost-effective broadband Internet accesses to users. The off-the-shelf IEEE 802.11 PHY and MAC specifications support both multi-channel and multi-rate capabilities. However, designing an efficient channel assignment protocol that exploits both available channels and data rates is a critical issue to overcome the network performance degradation. In multi-rate wireless networks, high-rate links may severely suffer from throughput degradation due to the presence of low-rate links. This problem is often referred to as performance anomaly. In this paper, we design a Cooperative Channel Assignment (CoCA) protocol to consider the performance anomaly problem in multi-channel multi-rate WMNs. Based on the proposed family architecture, CoCA exploits the Estimated Delivery Time (EDT) metric and an efficient balancing algorithm. Using the EDT metric, CoCA performs channel assignments to form Multi-channel Multi-hop Paths (MMPs) so that CoCA separates high-rate links from low-rate links over different channels and increases the channel diversity. In addition, CoCA considers the performance anomaly problem and throughput fairness during channel assignments by utilizing the balancing algorithm. We evaluated the performance of CoCA through extensive simulations and found that CoCA outperforms existing well-known channel assignment protocols for WMNs.

A hybrid QoS multicast framework-based protocol for wireless mesh networks

In recent years wireless mesh networks have been deployed and grown in popularity in many metropolitan areas. The deployment of such networks has allowed clients to gain access to publicly available broadband networks. The lack of standards and support for multicasting over wireless mesh networks makes this area very challenging as well as providing much scope for improvement. For first time in this paper, we use CMAC neural network model to predict route or node disconnection probability and to control congestion and losses specifically in the gateways. This prediction leads to recover the network before fault occurrence. In this paper, we propose a new QoS multicast routing framework for WMNs to solve the problem of load balancing and to enhance the QoS in multicast communication among Internet hosts and Mesh hosts dynamically. We also present an optimized hybrid multicast protocol based on this framework called HMFPM provisioning problems in the Next-Generation IEEE 802.11 s. The proposed protocol combines Proactive and Reactive multicast routing to eliminate unnecessary delays and also minimize control overhead in setting up routes amongst the backbone mesh routers. It also supports multiple gateways for the gateway balancing and routing based on CMAC prediction in each node to have the routes with least miss ratio.

Providing QoE and QoS in Wireless Mesh Networks Through Dynamic Choice of Routing Metrics

The increasing demand of multimedia applications requires a new behavior of routing protocols for wireless mesh networks (WMNs). It is necessary to support the minimum requirements for quality of service (QoS), but WMNs also need to support the minimum requirements for quality of experience (QoE). This paper is an additional analysis of the proposed routing protocol OLSR-DC, from a perspective of the network (QoS) and from a perspective of the user (QoE). The simulations were performed to demonstrate the performance of OLSR-DC compared against original OLSR and its ETX and MD versions considering different performance evaluation metrics and the quality of the video received by the user.

VirtualMesh: an emulation framework for wireless mesh and ad hoc networks in OMNeT++

Wireless Mesh Networks (WMNs) have proven to be a key technology for increased network coverage of Internet infrastructures. The development process for new WMN protocols and architectures is typically split into evaluation by network simulation and testing of a prototype in a test-bed. Testing in simulation often requires the developer to write software that is not directly portable to test-beds, whereas pure prototype testing on real hardware is time consuming and expensive. Irrepressible external interferences can occur, which make debugging difficult. Moreover, the test-bed usually supports only a limited number of test topologies and sites. Finally, mobility tests are impractical. Therefore, we propose VirtualMesh as a novel testing architecture, which can be used before evaluating in a real test-bed. It provides instruments to test the real communication software, including the network stack inside a controlled environment. VirtualMesh has been implemented by capturing real traffic through a virtual interface at the mesh nodes. The traffic is then redirected to the network simulator OMNeT++. In our experiments, VirtualMesh has proven to be scalable, to have minimal influence on throughput and to introduce only negligible delays (less than 0.4 ms per hop). Hence, it is a valuable tool for protocol and application developers to test their software prior to the final deployment.

Using fuzzy link cost and dynamic choice of link quality metrics to achieve QoS and QoE in wireless mesh networks

The growth of multimedia applications and wireless systems requires a new behavior of routing protocols for wireless mesh networks (WMNs). It is necessary to provide not only the minimum requirements for quality of service (QoS), but also to assure the quality of experience (QoE) support for multimedia applications. In this context, the usage of only one link quality metric for routing different types of packets within the network is not enough to ensure applications with suitable QoS and QoE levels. This paper presents a variation of the WMN routing protocol optimized link state routing (OLSR), to achieve QoS and QoE requirements for multimedia applications. It is based on the dynamic choice of metrics and in a fuzzy link cost (FLC) to determine the best routes for multimedia packets. The proposed FLC metric is based on a fuzzy system that uses two link quality metrics, namely expected transmission count (ETX) and minimum delay (MD), to define a new metric. Simulations were performed to demonstrate the performance of the proposed metric compared to the ones present in the original OLSR and other current versions of this protocol. For comparison purposes, it was considered different performance evaluation QoS metrics and the quality of videos received by the user in a higher competition scenario.

A Review of Routing Protocols in Wireless Mesh Networks

A Review of Routing Protocols in Wireless Mesh Networks

A reactive and dependable transport protocol for wireless mesh networks

In the last few years, several different mesh network architectures have been conceived by both industry and academia; however, many issues on the deployment of efficient and fair transport protocols are still open. One of these issues is rate adaptation, that is, how to allocate the network resources among multiple flows, while minimizing the performance overhead. In order to address this problem, in this paper, we first define an analytical framework for a very simple topology. The model allows us to study the performance of an adaptive and responsive transport protocol when the effect of the lower layers are ignored. The mathematical approach alone does not represent a feasible solution, but it contributes to determining the strengths and weaknesses of our proposal. The main novelty of the proposed solution is that the congestion control approach is based on a hop-by-hop mechanism, which allows nodes to adapt their transmitting rates in a distributed way and to keep track of dynamic multi-hop network characteristics in a responsive manner. This is in contrast with classical literature solutions, founded on an end-to-end support. Anyway, to ensure the reliability, a coarse-grained end-to-end algorithm is integrated with the proposed hop-by-hop congestion control mechanism to provide packet level reliability at the transport layer. Performance evaluation, via extensive simulation experiments, shows that the proposed protocol achieves a high performance in terms of network throughput.

An Efficient and User Privacy-Preserving Routing Protocol for Wireless Mesh Networks

Wireless mesh networks (WMNs) have emerged as a key technology for next generation wireless broadband networks showing rapid progress and inspiring numerous compelling applications. A WMN comprises of a set of mesh routers (MRs) and mesh clients (MCs), where MRs are connected to the Internet backbone through the Internet gateways (IGWs). The MCs are wireless devices and communicate among themselves over possibly multi-hop paths with or without the involvement of MRs. User privacy and security have been primary concerns in WMNs due to their peer-to-peer network topology, shared wireless medium, stringent resource constraints, and highly dynamic environment. Moreover, to support real-time applications, WMNs must also be equipped with robust, reliable and efficient routing protocols so as to minimize the end-to-end latency. Design of a secure and efficient routing protocol for WMNs, therefore, is of paramount importance. In this paper, we propose an efficient and reliable routing protocol that also provides user anonymity in WMNs. The protocol is based on an accurate estimation of the available bandwidth in the wireless links and a robust estimation of the end-to-end delay in a routing path, and minimization of control message overhead. The user anonymity, authentication and data privacy is achieved by application of a novel protocol that is based on Rivest's ring signature scheme. Simulations carried out on the proposed protocol demonstrate that it is more efficient than some of the existing routing protocols.

Multi-Fractal Characteristics of Mobile Node’s Traffic in Wireless Mesh Network with AODV and DSDV Routing Protocols

The analysis of traffic characteristics can be used for performance evaluation, design and implementation of routing protocols in WMNs (Wireless Mesh Networks). Higher bursty traffic will cause larger queue size, which means more dropping packets, and thus affects other metrics. Because burstiness can be modeled by multi-fractal characteristics effectively, multi-fractal characteristics of mobile node's traffic in WMNs are analyzed with typical proactive and reactive routing protocols, which are DSDV (Destination Sequenced Distance Vector) and AODV (Ad hoc On-demand Distance Vector), respectively. Three types of traffic models are used to generate traffic at application level, which corresponding to open-loop and closed-loop scenarios. With different configurations, the probability distribution of inter-arrival time and multi-fractal characteristics of traffic at mobile node and gateway are analyzed with DSDV and AODV protocols. Results show that inter-arrival time with AODV and DSDV protocols possesses heavy-tailed property. And traffic with DSDV protocol exhibits more multi-fractal characteristics than that with AODV protocol, which can explain the higher routing performance of AODV.

Dynamic Metric Choice Routing for Wireless Mesh Networks

The increasing demand of multimedia applications requires a new conduct of routing protocols for Wireless Mesh Networks (WMN). It is necessary to support the minimum requirements for Quality of Service (QoS). In this work we propose an extension to the proactive Optimized Link State Routing (OLSR) protocol that differentiates the data traffic and multimedia traffic, in order to provide quality of service and support to applications which use TCP as their transport protocol. The proposal performance, called OLSR Dynamic Choice (OLSR-DC), is evaluated using the Network Simulator

Orthogonal Rendezvous Routing Protocol for Wireless Mesh Networks

Routing in multi-hop wireless networks involves the indirection from a persistent name (or ID) to a locator. Concepts such as coordinate space embedding help reduce the number and dynamism complexity of bindings and state needed for this indirection. Routing protocols which do not use such concepts often tend to flood packets during route discovery or dissemination, and hence have limited scalability. In this paper, we introduce Orthogonal Rendezvous Routing Protocol (ORRP) for meshed wireless networks. ORRP is a lightweight-but-scalable routing protocol utilizing directional communications (such as directional antennas or free-space-optical transceivers) to relax information requirements such as coordinate space embedding and node localization. The ORRP source and ORRP destination send route discovery and route dissemination packets respectively in locally-chosen orthogonal directions. Connectivity happens when these paths intersect (i.e., rendezvous). We show that ORRP achieves connectivity with high probability even in sparse networks with voids. ORRP scales well without imposing DHT-like graph structures (eg: trees, rings, torus etc). The total state information required is O(N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3/2</sup> ) for N-node networks, and the state is uniformly distributed. ORRP does not resort to flooding either in route discovery or dissemination. The price paid by ORRP is suboptimality in terms of path stretch compared to the shortest path; however we characterize the average penalty and find that it is not severe.

Call for Papers: Special Issue on “Architectures and Protocols for Wireless Mesh, Ad Hoc, and Sensor Networks”

Call for Papers: Special Issue on “Architectures and Protocols for Wireless Mesh, Ad Hoc, and Sensor Networks”

Exploring the design space of reliable multicast protocols for wireless mesh networks

Many important applications in wireless mesh networks require reliable multicast communication, i.e., with 100% packet delivery ratio (PDR). Previously, numerous multicast protocols based on automatic repeat request (ARQ) have been proposed to improve the packet delivery ratio. However, these ARQ-based protocols can lead to excessive control overhead and drastically reduced throughput. In this paper, we present a comprehensive exploration of the design space for developing high-throughput, reliable multicast protocols that achieve 100% PDR. Motivated by the fact that 802.11 MAC layer broadcast, which is used by most wireless multicast protocols, offers no reliability, we first examine if better hop-by-hop reliability provided by unicasting the packets at the MAC layer can help to achieve end-to-end multicast reliability. We then turn to end-to-end solutions at the transport layer. Previously, forward error correction (FEC) techniques have been proved effective for providing reliable multicast in the Internet, by avoiding the control packet implosion and scalability problems of ARQ-based protocols. In this paper, we examine if FEC techniques can be equally effective to support reliable multicast in wireless mesh networks. We integrate four representative reliable schemes (one ARQ, one FEC, and two hybrid) originally developed for the Internet with a representative multicast protocol ODMRP and evaluate their performance. Our experimental results via extensive simulations offer an in-depth understanding of the various choices in the design space. First, compared to broadcast-based unreliable ODMRP, using unicast for per-hop transmission only offers a very small improvement in reliability under low load, but fails to improve the reliability under high load due to the significantly increased capacity requirement which leads to congestion and packet drop. Second, at the transport layer, the use of pure FEC can significantly improve the reliability, increasing PDR up to 100% in many cases, but can be inefficient in terms of the number of redundant packets transmitted. In contrast, a carefully designed ARQ–FEC hybrid protocol, such as RMDP, can also offer 100% reliability while improving the efficiency by up to 38% compared to a pure FEC scheme. To our best knowledge, this is the first in-depth study of high-throughput, reliable multicast protocols that provide 100% PDR for wireless mesh networks.

A Hybrid Centralized Routing Protocol for 802.11s WMNs

Wireless mesh networks (WMNs) are being widely accepted as a critical wireless access solution for various applications. Due to minimal mobility in mesh nodes, a backbone topology can be effectively maintained in WMN using a proactive routing protocol. In IEEE 802.11s standard, a tree-based routing (TBR) protocol is adopted as a viable proactive routing protocol for aWMN with user traffic flowing to/from a wired network through a root (i.e., a mesh portal). However, the performance of the TBR protocol degrades rapidly as the user traffic becomes dominated by intra-mesh traffic. The reason is that the routing path through the root even for intra-mesh traffic unnecessarily overloads the root. Furthermore, the TBR performance becomes more severe when the network size of WMN is large, which could lead to the huge amount of intra-mesh traffic towards the root. To overcome these problems, we propose a new routing mechanism, root driven routing (RDR) protocol, for the root to quickly determine the best-metric route for any source-destination pair of intra-mesh traffic. For inter-mesh traffic, the original TBR protocol is employed. Thus, the hybrid centralized routing protocol that combines TBR and RDR and is adaptive to all traffic scenarios. Our simulation results reveal that the proposed RDR protocol outperforms the TBR protocol with much lower average end-to-end delay and much higher packet delivery ratio for intra-mesh traffic. The simulation results also provide some insight into the right tradeoff between the TBR protocol and the RDR protocol to achieve the best performance of the hybrid centralized routing protocol for WMNs.

A link layer adaptive pacing scheme for improving throughput of transport protocols in wireless mesh networks

In this paper, we study the performance of a static multihop wireless network, specifically that of the backhaul network of a two-tier Wireless Mesh Network (WMN) operating on IEEE 802.11 Medium Access Control (MAC) protocol. The performance of an IEEE 802.11 based backhaul network is greatly affected by the MAC contention and congestion in the network. If the sources pump data into the network than can be supported, loss rate increases due to MAC contention and congestion in the network. This also leads to the problem of unfairness among flows. In this paper, we propose a Link Layer Adaptive Pacing (LLAP) scheme that adaptively controls the offered load into the network. This improves the performance of higher layer protocols without any modifications to them. Our LLAP scheme estimates the four hop transmission delay in the network path without incurring any additional overhead (Control packets) and accordingly paces the packet transmissions to reduce MAC contentions in the network. We implement the LLAP scheme in ns-2.29 network simulator and extensively study its performance for both User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) traffic in different network scenarios. In all the cases, our scheme shows a significant improvement in the performance of both UDP and TCP traffic.