Search Results for « Wireless Mesh Network »

In this paper, we derive the information theoretic capacity of a special class of mesh networks. A mesh network is a heterogeneous wireless network in which the transmission among power limited nodes is assisted by powerful relays, which use the same wireless medium. We investigate the mesh network when there is one source, one destination, and multiple relays, which we call the single source multiple relay single destination (SSMRSD) mesh network. We derive the asymptotic capacity of the SSMRSD mesh network when the relay powers grow to infinity. Our approach is as follows. We first look at an upper bound on the information theoretic capacity of these networks in a Gaussian setting. We then show that this bound is achievable asymptotically using the compress-and-forward strategy for the multiple relay channel. We also perform numerical computations for the case when the relays have finite powers. We observe that even when the relay power is only a few times larger than the source power, the compress-and-forward rate gets close to the capacity. The results indicate the value of cooperation in wireless mesh networks. The capacity characterization quantifies how the relays can cooperate, using the compress-and-forward strategy, to either conserve node energy or to increase transmission rate.

Wireless networking is encouraged by the constant enhancement of sensors' ability and wireless communication. To provide service quality support for multimedia viz. audio and video streams, the IEEE 802.11e MAC (Media Access Control) improves basic 802.11 MAC. IEEE 802.11 standard series such as IEEE 802.11a, b, g, n, p, and ac have been promoted and specified in the current communications and connection development. Each standard has functionality that matches the kind of applications for which the standard is intended. IEEE 802.11ac has better performance with fewer interferences and achieves gigabits per second capacity transfer rates. This paper discusses the comparative examination of the IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, IEEE 802.11p, and IEEE 802.11ac standards which increase accuracy and performance pertaining to the IEEE 802.11 standard. In this paper, we investigate the design requirements for numerous simultaneous peer-to-peer connections. Further, this study offers a systematic review and analysis of the MAC layer in WMN (Wireless Mesh Network) and also highlights their open research issues and challenges. Finally, this paper discusses various potential directions for future research in this area with an emphasis on their strengths and limitations.

Interference is one of the most challenging issues in wireless network. Communication between a transmitter and receiver pair causes radio wave propagation to interfere with other nearby communication that may result blocking that link. In Multicast, since almost simultaneous communication takes place along several branches of a Multicast distribution tree, these branches tend to mutually block each other due to interference. In this research we introduced an Interference-Aware Multicast routing protocol. First, it divides the nodes in the Multicast distribution tree in three GORby-Groups: Transmit, REC1 (receiving) and REC2 (standby). Then we calculate the SINR of the node based on interferences caused by all the nodes within that GORby-Group, assuming when the given node is in the transmit mode then all the nodes within its GORby-Group will also be in the transmit mode. Then we use the computed SINRs in our join Multicast group algorithm to achieve the most SINR.

Wireless Mesh Network (WMN) is surely one of the prominent networks in the modern era which is widely used in numerous evolving applications, viz. broadband home networking (BHN), community and neighbourhood networks (CNN), coordinated network management (CNM), and intelligent transportation systems (ITS), etc. It is a wireless network (WN) with multi-hop formed by many fixed wireless mesh routers (WMR) that are connected wirelessly with a mesh-alike backbone arrangement. In the IEEE 802.11s network, the node selection, scalability, stability, density of the nodes, mobility of the nodes, transmission power, and routing are major issues that WMN suffers. In this paper, a critical review of MAC protocols and their Quality of Service (QoS) parameters for WMN is presented to attain a better understanding of MAC protocols. Furthermore, the critical comparative analysis and recommendation of MAC procedures for WMN using Multi-objective optimization and statistical testing framework are performed. This framework is used for the analysis and recommendation of different protocols available for QoS parameters.

<p>Wireless mesh network (WMN) is popular for providing decentralized and relatively inexpensive Internet access, especially in Community network and geographically challenged areas of deployment. In this thesis, we proposed using OSPF as the underlying routing protocol in the Wireless Mesh Backbone (WMB) network. We investigated the convergence and configuration issues of OSPF in WMB network. We evaluated the performance of OSPF and compared with AODV (reactive ad hoc protocol) and OLSR (proactive ad hoc protocol). We proposed using multiple subinterfaces under a single physical wireless interface in configuring multiple subnets to deal with the hidden nodes problem in WMB networks. We also proposed using the BGP protocol to interconnect multiple OSPF areas for the sub-urban topology. The performance of this approach in terms of convergence time was studied. </p>

Wireless mesh networks (WMNs) have emerged as a promising concept to meet the challenges in next-generation networks such as providing flexible, adaptive, and reconfigurable architecture while offering cost-effective solutions to the service providers. Unlike traditional Wi-Fi networks, with each access point (AP) connected to the wired network, in WMNs only a subset of the APs are required to be connected to the wired network. The APs that are connected to the wired network are called the Internet gateways (IGWs), while the APs that do not have wired connections are called the mesh routers (MRs). The MRs are connected to the IGWs using multi-hop communication. The IGWs provide access to conventional clients and interconnect ad hoc, sensor, cellular, and other networks to the Internet. However, most of the existing routing protocols for WMNs are extensions of protocols originally designed for mobile ad hoc networks (MANETs) and thus they perform sub-optimally. Moreover, most routing protocols for WMNs are designed without security issues in mind, where the nodes are all assumed to be honest. In practical deployment scenarios, this assumption does not hold. This chapter provides a comprehensive overview of security issues in WMNs and then particularly focuses on secure routing in these networks. First, it identifies security vulnerabilities in the medium access control (MAC) and the network layers. Various possibilities of compromising data confidentiality, data integrity, replay attacks and offline cryptanalysis are also discussed. Then various types of attacks in the MAC and the network layers are discussed. After enumerating the various types of attacks on the MAC and the network layer, the chapter briefly discusses on some of the preventive mechanisms for these attacks.

Interference is one of the most challenging issues in wireless network. Communication between a transmitter and receiver pair causes radio wave propagation to interfere with other nearby communication that may result blocking that link. In Multicast, since almost simultaneous communication takes place along several branches of a Multicast distribution tree, these branches tend to mutually block each other due to interference. In this research we introduced an Interference-Aware Multicast routing protocol. First, it divides the nodes in the Multicast distribution tree in three GORby-Groups: Transmit, REC1 (receiving) and REC2 (standby). Then we calculate the SINR of the node based on interferences caused by all the nodes within that GORby-Group, assuming when the given node is in the transmit mode then all the nodes within its GORby-Group will also be in the transmit mode. Then we use the computed SINRs in our join Multicast group algorithm to achieve the most SINR.

Wireless mesh networks (WMNs) have emerged as a promising concept to meet the challenges in next-generation wireless networks such as providing flexible, adaptive, and reconfigurable architecture while offering cost-effective solutions to service providers. As WMNs become an increasingly popular replacement technology for last-mile connectivity to the home networking, community and neighborhood networking, it is imperative to design efficient and secure communication protocols for these networks. However, several vulnerabilities exist in currently existing protocols for WMNs. These security loopholes can be exploited by potential attackers to launch attack on WMNs. The absence of a central point of administration makes securing WMNs even more challenging. The broadcast nature of transmission and the dependency on the intermediate nodes for multi-hop communications lead to several security vulnerabilities in WMNs. The attacks can be external as well as internal in nature. External attacks are launched by intruders who are not authorized users of the network. For example, an intruding node may eavesdrop on the packets and replay those packets at a later point of time to gain access to the network resources. On the other hand, the internal attacks are launched by the nodes that are part of the WMN. On example of such attack is an intermediate node dropping packets which it was supposed to forward. This chapter presents a comprehensive discussion on the current authentication and privacy protection schemes for WMN. In addition, it proposes a novel security protocol for node authentication and message confidentiality and an anonymization scheme for privacy protection of users in WMNs.

<p>Wireless mesh network (WMN) is popular for providing decentralized and relatively inexpensive Internet access, especially in Community network and geographically challenged areas of deployment. In this thesis, we proposed using OSPF as the underlying routing protocol in the Wireless Mesh Backbone (WMB) network. We investigated the convergence and configuration issues of OSPF in WMB network. We evaluated the performance of OSPF and compared with AODV (reactive ad hoc protocol) and OLSR (proactive ad hoc protocol). We proposed using multiple subinterfaces under a single physical wireless interface in configuring multiple subnets to deal with the hidden nodes problem in WMB networks. We also proposed using the BGP protocol to interconnect multiple OSPF areas for the sub-urban topology. The performance of this approach in terms of convergence time was studied. </p>