A Survey on MAC Layer Security Challenges in WMNs

The popularity and the constant improvement of wireless technologies, such as WiFi and WiMAX, have been increasing the usage and applicability of new networking schemes, including Wireless Mesh Networks (WMNs). WMNs are multi-hop wireless networks made by a collection of two types of nodes, mesh routers and mesh clients. Their self-organizing, self-configuring and self-healing proprieties, in conjunction with their low maintenance and implementation costs, make them especially appealing as a solution for Internet access and social networking. The characteristics of WMNs make them more susceptible to malicious attacks than traditional wired networks, namely the scarce bandwidth, the high level of interference, the shared transmission media and the limited physical security. Secure routing and forwarding schemes are a key component to guarantee secure communications in hostile environments. There are however issues that must be considered when developing secure routing and forwarding solutions, namely the overhead introduced by such approaches and the effectiveness of the prediction schemes used. This paper discusses the main solutions for routing security in WMNs and presents a thorough evaluation, comprising a novel way to characterize the effectiveness of such approaches. The evaluation is based on CONFIDANT, a secure routing protocol based on the DSR protocol. The study performed addresses both the issues aforementioned and provides insight on the trade-offs associated with the deployment of secure routing and forwarding mechanisms.

Wireless Mesh Network (WMN) is recently emerged network having robustness. It supports clients to communicate with different types of networks, Internet etc which provides a better service to next generation. It consists of mesh routers and mesh clients. These mesh routers are minimal mobile and mesh clients are totally mobile. The protocols of Ad hoc network are used in WMN. These protocols assume that every node is mobile. But as the mesh routers are minimal mobile or not mobile, the protocols brings overhead for the mesh routers. Our task is to relieve mesh routers using ad hoc network protocol from the overhead and define a better protocol which will fit in WMN efficiently. To do so, we've found that the existing architecture of WMN is needed to be changed slightly. We have proposed a new architecture for Wireless Mesh Network. In our proposal WMN is relieved from overhead being caused by using ad hoc network protocol. Our architecture use unicasting technique in lieu of broadcasting technique for route discovery as well as route maintenance. We will first describe the overview of WMN, its existing architecture. Later we will go to our proposed architecture.

ITS hybrid Wireless Mesh Network (WMN) is special case of WMN containing relatively static mesh points and mobile mesh clients, which may suffer from random variations in channel and network condition and handoff problems due to mobility of mesh clients. This leads to poor performance in multi-hop WMN, especially with conventional non-flexible routing algorithms. To cope with instability of wireless links and fast handoff between mesh points for mobile mesh clients, a cross-layer routing that supports link quality optimization and stable routing is an effective way. The key technology is focusing on the choice of the route metrics. In this paper we propose a novel Link Quality and Stability-aware metric from MAC layer supporting Cross-layer Routing (LQSCR) for hybrid WMN. LQSCR selects the path which has best link quality and highest neighbor stability ratio to forward data. Analysis and simulation results show that LQSCR may achieves better performance in hybrid WMN in terms of end-to-end delay, jitter delay and packet delivery ratio in comparison to shortest path metric.

A wireless mesh network is a mesh network implemented over a wireless network system such as wireless LANs. Wireless Mesh Networks(WMNs) are promising for numerous applications such as broadband home networking, enterprise networking, transportation systems, health and medical systems, security surveillance systems, etc. Therefore, it has received considerable attention from both industrial and academic researchers. This dissertation explores schemes for resource management and optimization in WMNs by means of network routing and network coding. In this dissertation, we propose three optimization schemes. (1) First, a triple-tier optimization scheme is proposed for load balancing objective. The first tier mechanism achieves long-term routing optimization, and the second tier mechanism, using the optimization results obtained from the first tier mechanism, performs the short-term adaptation to deal with the impact of dynamic channel conditions. A greedy sub-channel allocation algorithm is developed as the third tier optimization scheme to further reduce the congestion level in the network. We conduct thorough theoretical analysis to show the correctness of our design and give the properties of our scheme. (2) Then, a Relay-Aided Network Coding scheme called RANC is proposed to improve the performance gain of network coding by exploiting the physical layer multi-rate capability in WMNs. We conduct rigorous analysis to find the design principles and study the tradeoff in the performance gain of RANC. Based on the analytical results, we provide a practical solution by decomposing the original design problem into two sub-problems, flow partition problem and scheduling problem. (3) Lastly, a joint optimization scheme of the routing in the network layer and network coding-aware scheduling in the MAC layer is introduced. We formulate the network optimization problem and exploit the structure of the problem via dual decomposition. We find that the original problem is composed of two problems, routing problem in the network layer and scheduling problem in the MAC layer. These two sub-problems are coupled through the link capacities. We solve the routing problem by two different adaptive routing algorithms. We then provide a distributed coding-aware scheduling algorithm. According to corresponding experiment results, the proposed schemes can significantly improve network performance.

Wireless Mesh Networks (WMNs) are gaining a lot of attention from researchers due to their advantages such as easy maintenance, low upfront cost and high robustness. Connectivity and stability directly affect the performance of WMNs. However, WMNs have some problems such as node placement problem, hidden terminal problem and so on. In our previous work, we implemented a simulation system to solve the node placement problem in WMNs considering Particle Swarm Optimization (PSO) and Distributed Genetic Algorithm (DGA), called WMN-PSODGA. In this paper, we compare chi-square and uniform distributions of mesh clients for different router replacement methods. The router replacement methods considered are Constriction Method (CM), Random Inertia Weight Method (RIWM), Linearly Decreasing Inertia Weight Method (LDIWM), Linearly Decreasing Vmax Method (LDVM) and Rational Decrement of Vmax Method (RDVM). The simulation results show that for chi-square distribution the mesh routers cover all mesh clients for all router replacement methods. In terms of load balancing, the method that achieves the best performance is RDVM. When using the uniform distribution, the mesh routers do not cover all mesh clients, but this distribution shows good load balancing for four router replacement methods, with RIWM showing the best performance. The only method that shows poor performance for this distribution is LDIWM. However, since not all mesh clients are covered when using uniform distribution, the best scenario is chi-square distribution of mesh clients with RDVM as a router replacement method.

A wireless mesh network (WMN) comprises of mesh access points (MAPs), mesh routers and mesh clients (MCs), where MAPs are almost static and form the back-bone of WMNs. MCs are wireless devices and dynamic in nature, communicating among themselves over possibly multi-hop paths, with or without the help of MAPs. Security has been a primary concern in order to provide protected communication in WMNs due to the open peer-to-peer network topology, shared wireless medium, stringent resource constraints and highly dynamic environment. These challenges clearly make a case for building multi-layer security solution that achieves both broad protection and desirable network performance. In this paper, we propose a cross-layer secure protocol for routing, data exchange and ARP problems (in case of LAN based upon WMNs). Our protocol is a ticket-based ad hoc on demand distance vector (TAODV) protocol, a secure routing protocol that is based on the design of ad hoc on demand distance vector (AODV) protocol. Due to availability of the backbone, we incorporate the authentication server (AS) for the issuance of tickets which are further used for secure routing, transfer of public keys and MAC addresses in one single step. With the transfer of public keys, source and destination can easily generate their shared secret key based upon fixed Diffie-Hellman key exchange protocol for data encryption and decryption. Our protocol is secure against both active and passive attacks.

Mesh Client (MC) may be frequently move from the current SMAP to another SMAP in the Wireless Mesh Networks (WMN). The most of the present research papers on WMN assume that the MC is static or quasi static. However, MC may constantly move actually, which connection interruption and packet loss may occur. To solve these problems this paper presents a mobility support strategy for WMN, which consists of two parts: address assignment and mobility management.

Efficient multicasting over Wireless Mesh Network (WMN) is challenging due to dynamic and multi-hop wireless communication among multicast group members. Multicast Ad hoc On-Demand Distance Vector (MAODV) protocol is a tree based multicast routing protocol that enables dynamic, self-starting, multi-hop routing between participating mobile nodes wishing to join or participate in a multicast group in Wireless Mesh Network (WMN). The mobility of mobile nodes often causes link breakage in the tree-based protocols which sometime results in tree partitioning and poor performance. In MAODV, when a broken link is detected between two nodes on the multicast tree, the node downstream to the break is responsible for initiating the repair of the broken link. After link repair, it is likely that the previous distance between the nodes (nodes downstream to the link breakage) and the group leader will not remain same. The shortest path from the group leader to the nodes downstream to the node which initiates link breakage is not ensured. Moreover, if the node attempting to repair a tree link break does not receive a response after certain attempts, it assumes that the multicast tree is not repairable currently and this leads to tree partitioning. In this paper, an improved link repair technique is proposed which ensures shortest path from any node to the group leader. Simulation results demonstrate significant improvement in performance metrics compared to standard MAODV.

Wireless mesh networks (WMNs) are wireless multihop networks comprised of mesh routers, which relay traffic on behalf of clients and other nodes. Using the standard IEEE 802.11 distributed coordination function (DCF) as MAC layer, a node needs to contend for the medium each time it wants to transmit a packet. This creates high overhead in particular for small packets and leads to poor performance for real-time applications such as Voice over IP (VoIP) or online gaming. Burst packet transmission can increase the efficiency. For example, with the Transmission Opportunity limit (TXOPlimit) in IEEE 802.11e, a station may transfer several packets without contending for the channel in between. Similarly, IP packet aggregation combines several IP packets together and sends them as one MAC Service Data Unit. Originally, both schemes have been developed for singlehop networks only. Thus the impact on WMNs is unclear if the packets need to contend over multiple hops. In this paper, we use measurements from a 9-node WMN testbed to compare TXOPs and IP packet aggregation for VoIP in terms of fairness, network capacity and quality of user experience. We show that for low networks loads, both TXOPs and IP packet aggregation increase the VoIP quality compared to IEEE 802.11 DCF. However, in highly loaded networks IP packet aggregation outperforms the other schemes.

Wireless mesh networks (WMNs) have emerged as a scalable, reliable, and agile wireless network that supports many types of innovative technologies such as the Internet of Things (IoT), Wireless Sensor Networks (WSN), and Internet of Vehicles (IoV). Due to the limited number of orthogonal channels, interference between channels adversely affects the fair distribution of bandwidth among mesh clients, causing node starvation in terms of insufficient bandwidth distribution, which impedes the adoption of WMN as an efficient access technology. Therefore, a fair channel assignment is crucial for the mesh clients to utilize the available resources. However, the node starvation problem due to unfair channel distribution has been vastly overlooked during channel assignment by the extant research. Instead, existing channel assignment algorithms equally distribute the interference reduction on the links to achieve fairness which neither guarantees a fair distribution of the network bandwidth nor eliminates node starvation. In addition, the metaheuristic-based solutions such as genetic algorithm, which is commonly used for WMN, use randomness in creating initial population and selecting the new generation usually leading the search to local minima. To this end, this study proposes a Fairness-Oriented Semichaotic Genetic Algorithm-Based Channel Assignment Technique (FA-SCGA-CAA) to solve node starvation problem in wireless mesh networks. FA-SCGA-CAA maximizes link fairness while minimizing link interference using a genetic algorithm (GA) with a novel nonlinear fairness-oriented fitness function. The primary chromosome with powerful genes is created based on multicriterion links ranking channel assignment algorithm. Such a chromosome was used with a proposed semichaotic technique to create a strong population that directs the search towards the global minima effectively and efficiently. The proposed semichaotic technique was also used during the mutation and parent selection of the new genes. Extensive experiments were conducted to evaluate the proposed algorithm. A comparison with related work shows that the proposed FA-SCGA-CAA reduced the potential node starvation by 22% and improved network capacity utilization by 23%. It can be concluded that the proposed FA-SCGA-CAA is reliable to maintain high node-level fairness while maximizing the utilization of the network resources, which is the ultimate goal of many wireless networks.

In a wireless mesh network (WMN), mesh clients (MCs) access the Internet through the wireless backbone formed by the Internet Gateways (IGWs) and Mesh Routers (MRs). An IGW as the traffic center may easily become the congestion center in a WMN. The load balancing between IGWs will reduce the traffic congestion thereby improving the network performance and providing a better quality of service (QoS). In this paper, potential load balancing between different IGW service domains is examined and fairness metrics are defined for both homogenous and heterogeneous WMNs. A distributed load balancing scheme based on diffusion methods is proposed to achieve a global load fairness. The effectiveness and efficiency of proposed load balancing scheme are verified by extensive simulations.

In a wireless mesh network (WMN), mesh clients (MCs) access the Internet through the wireless backbone formed by the Mesh Routers (MRs) and Internet Gateways (IGWs). Internet Gateways are the traffic center in each IGW service domain thus may also become the congestion center. To improve the performance of a WMN, the load balancing between different IGW service domains is investigated. The load fairness between IGWs domains will improve the network performance and provides a better quality of service (QoS) for end users. In this paper, the fairness index is defined for both homogenous and heterogeneous WMNs. A probabilistic load balancing algorithm based on the simulated annealing method is proposed to get the global load fairness.

Wireless mesh network (WMN) is considered as one of most emerging field for the research work in today's networking area due to its various approaches available to handle the network resources. Various architectures have been proposed so far and main key challenge for the design of this network is their vulnerability to security attacks. Therefore an efficient key management is required to overcome from such security exploitation such as unauthorised access to the network. WMNs need to be clustered into multiple groups to achieve fast and efficient security mechanism to overcome from security attacks. Therefore, we have proposed a group key agreement protocol based on Diffie-Hellman protocol and digital signature to authenticate the mesh entities within the group. The authentication took place between trusted authority (TA) and mesh clients with efficient communication and computational cost and results in reduction of packet loss by an attacker in wireless network which improves the overall performance of the WMNs. Our experimental result proves that it achieves better communication and computational cost with non-repudiation attack.

Wireless Mesh Network (WMN) is a multi hop low cost, with easy maintenance robust network providing reliable service coverage. WMNs consist of mesh routers and mesh clients. In this architecture, while static mesh routers form the wireless backbone, mesh clients access the network through mesh routers as well as directly meshing with each other. Different from traditional wireless networks, WMN is dynamically self-organized and self-configured. In other words, the nodes in the mesh network automatically establish and maintain network connectivity. Over the years researchers have worked, to reduce the redundancy in broadcasting packet in the mesh network in the wireless domain for providing reliable service coverage, the source node deserves to broadcast or flood the control packets. The redundant control packet consumes the bandwidth of the wireless medium and significantly reduces the average throughput and consequently reduces the overall system performance. In this paper I study the optimization problem in Wireless Mesh Networks. We have proposed a novel approach to reduce the broadcast redundant packet in the wireless mesh network. Also we have shown, a novel procedure to forward the control packet to the destination nodes and efficiently minimize the transmitted control packet in the wireless mesh cloud , that covers the domain.

Providing security and privacy to users are critical in wireless mesh networks (WMNs). In this paper, a distributed security architecture is introduced to manage the mesh clients and a secure routing scheme that preserves the privacy of the end-users is proposed. In order to maximize routing efficiency, key indexing is used and symmetric cipher is employed in most part of the proposed scheme to reduce computational complexity. Both single-hop mesh client to mesh router and multi-hop mesh client to mesh client secure anonymous routing are proposed and discussed. Security and anonymity analysis are conducted followed by a complete performance analysis of the proposed protocol focusing on the route establish time and the routing overhead. The results show a reasonable overhead that linearly increases with the number of intermediate nodes. It is also demonstrated that the proposed schemes perform well against a broad range of attacks.