Virtual Home Region Multi-Hash Location Management Service (VIMLOC) for Large-Scale Wireless Mesh Networks

In multi-channel wireless mesh networks (WMNs), it is significantly important to achieve efficient channel utilization. The channel assignment problem, which investigates how to seek a proper mapping between available channels and network interface cards (NICs) on mesh routers (MRs), is attracting more and more attention from the research community. However, most proposed channel assignment approaches assume that NICs are evenly placed on the MRs, and its amount is also pre-determined. Due to the non-uniform distribution of WMN traffic, the equal interface placement will inevitably cause that the bottleneck MRs suffer from NIC shortage, and MRs with less load only have a low utilization of NICs. Hence, in order to improve network performance and reduce network cost, interface placement should be considered carefully in the process of planning a WMN. In this paper, we investigate the joint interface placement and channel assignment problem, i.e., how to appropriately place NICs on MRs and assign channels to them. We first formulate the problem as a mixed integer linear programming (MILP) model, which aims to minimize the total number of NICs while satisfying logical link, link bandwidth, link interference and traffic demand constraints. Then, we propose an MILP-based heuristic algorithm, using iterated local search to obtain sub-optimal solutions efficiently. Finally, we conduct simulation experiments to compare the heuristic solutions with the optimal solutions, and the results show that our proposed heuristic algorithm can achieve good sub-optimal solutions. Moreover, the simulation results also demonstrate that the algorithm can be well applied in large-scale WMNs where the optimal solutions cannot be obtained, and can perform well under different traffic demands.

Over the past few years, wireless mesh networks (WMNs) have emerged to become a ubiquitous solution for providing wireless access at lower cost, greater flexibility, higher reliability and performance compared to conventional wireless local area network (WLANs). As the demand for delay sensitive real-time applications such as VOIP and streaming media grows, mobility management is becoming a critical function of WMN. Although Mobility management schemes designed for Mobile Ad Hoc Networks (MANETs) and traditional fixed networks might be useful for WMNs, mobility management in WMNs is still an active research issue because of the special properties of WMNs. This chapter focuses on the mobility management in wireless mesh networks, which takes into account the unreliability of wireless mesh links and other special properties of WMNs. The chapter began by discussing the special properties of WMNs and the general concepts of mobility management, and then gives an overview of the mobility management problems in wireless mesh networks (layer 2 handoff, vertical handoff and cross layer design, etc.) with some potential solutions.

Wireless mesh networks (WMNs) are gaining significant momentum as a promising technology for the next-coming state-of-the-art wireless networking. Among many factors, the performance of WMNs would be largely affected by the properness of the deployed routing protocols and the efficient usage of wireless resources. Routing protocols are required to well capture WMNs' features while wireless channels should be used efficiently in order to accommodate high amount of traffics over the mesh backbone. Recently, a Tree-based Routing (TBR) protocol become a popular state-of-the-art proactive routing protocol and its tree-based broadcasting become an often used technique. Though TBR protocol is well-suited for WMNs' architecture and the skewed nature of traffic toward the root, the protocol in its current form faces issues which has to be addressed. Specifically, when some or all nodes are equipped with multiple radios, to reduce collision and co-channel interference, not only the parent-child relationship but also the sibling relationship need to be constructed by the TBR protocol in the multi-channel WMNs. In this paper, we propose a hybrid tree-based protocol for concurrent routing and channel assignment over WMNs. The protocol makes use of sibling links to mitigate the aforementioned shortcomings of TBR protocol. Moreover, in order to address high backbone traffic, the protocol integrates a receiver-based channel assignment scheme. The protocol efficiently deploys the parent-child topological relationships of nodes to enhance efficiency of broadcast transmissions over receiver-based multi-channel WMNs. Simulation results over NS-2 network simulator reveal that our proposed hybrid tree-based protocol achieves much higher performance than the utilization of the original receiver-based CA and TBR protocol.

The current deployment of wireless mesh networks requires mobility management to track the current locations of mobile nodes around the network without service interruption. To do so, the Hierarchical Mobile IPv6 protocol has been chosen, which minimises the required signalling by introducing a new entity called the mobile anchor point to act as a local home agent for all visiting mobile nodes in a specific domain. It allows a mobile node to register its local/regional care-of addresses with a mobile anchor point by sending a local binding update message. However, the local binding update is quite sensitive; it modifies the routing to enable mobility in the wireless mesh networks. When a local binding update message is spoofed, an attacker can redirect traffic that is destined for legitimate mobile node either to itself or to another node. This situation leads to an increased risk of attacks. Therefore, this paper contributes to addressing this security issue based on wireless mesh networks by cryptography generation and verification of a mobile node’s local and regional care-of addresses, as well as the application of a novel method to verify the reachability of mobile node at claimed local care-of address. This is called the enhanced mobile anchor point registration protocol. The Scyther tool has been used to ensure the proposed protocol accuracy. Furthermore, the performance, in terms of the mobile anchor point registration delay and signalling overhead, is evaluated by using the OPNET modeller simulator.

The commercial proliferation of cellular voice and data service has placed a new challenge for mobile communication systems. Next-generation wireless systems are envisioned to have an all-IP-based infrastructure with the support of heterogeneous access technologies (Akyildiz et al., 2004). Under the circumstance, the Internet Protocol (IP) is selected as the common interconnection protocol to integrate disparate wireless systems, so that mobile users can roam among multiple wireless networks, regardless of the underlying different radio access technologies (Akyildiz et al., 2005; Makaya & Pierre, 2008; Mohanty & Xie, 2007). However, with the advent of new value-added services (video-conference, multimedia streaming, etc.) and novel concepts introduced into Long Term Evolution (LTE) architecture of the 4th Generation (4G) networks, provisioning efficient mobilitymanagement with quality of service guarantees and seamless handoff feature become even more important for next-generation wireless network design. Generally, mobility management allows mobile communication systems to locate roaming terminals for voice/data delivery as well as maintaining network connectivity when the terminal moves into a new service area (Akyildiz et al., 1999). Typically, such process contains two aspects: location management and handoff management (Quintero et al., 2004; Zhang et al., 2010). Location management enables telecommunication systems to find out the network attachment points of roaming nodes for call/data delivery. It usually contains two components: location update and call delivery (or data delivery). The former requires mobile nodes to provide the system with their location information, while the latter indicates that the system is queried for the location information of specific mobile nodes, and then services are delivered to them while they are away from their home network (Zhang et al., 2010). Handoff management aims to maintain network connectivity when mobile nodes change their network attachment points or access points. Obviously, handoff protocols need to preservemobile users’ network connectivity as they move from one network to another, while simultaneously reducing disruption to the ongoing call/data sessions. Therefore, reducing handoff delay and maximizing session continuity are always the primary goals of handoff management (Dimopoulou et al., 2005). Generally, handoff seamlessness means lower packet Performance Analysis of Seamless Handover in Mobile IPv6-based Cellular Networks 13

The popularity of P2P (Peer-To-Peer) systems is increased tremendously due to massive increase in the Internet based applications. Initially, P2P systems were mainly designed for wired networks but today people are using more wireless networks and therefore these systems are gaining popularity. There are many wireless networks available today and WMNs (Wireless Mess Networks) are gaining popularity due to hybrid structure. People are using structured P2P systems-based applications within perimeter of a WMN. Structured P2P WMNs will assist the community to fetch the relevant information to accomplish their activities. There are inherent challenges in the structured P2P network and increased in wireless environment like WMNs. Structured P2P systems suffer from many challenges like lack of content availability, malicious content distribution, poor search scalability, free riding behaviour, white washing, lack of a robust trust model etc. Whereas, WMNs have limitations like mobility management, bandwidth constraint, limited battery power of user's devices, security, maintenance etc. in remote/ forward areas. We exploit the better possibility of content availability and search scalability in this paper. We propose replication schemes based on the popularity of content for structured P2P system applications in community based WMNs. The analysis of the performance shows that proposed scheme performs better than the existing replication scheme in different conditions.

Realistic interference-free channel assignment for dynamic wireless mesh networks using beamforming

By the enormous increase in mobile nodes and diverse service requests on wireless networks, wireless mesh network(WMN) takes an interest as the solution for such requests. However, lots of issues which should be solved to deploy WMN are still remained. In the network layer, the performance improvement of routing protocols is the major issue of nowadays researches. WMN can be easily deployed by use of protocols for mobile ad-hoc networks(MANET) because it is much similar with MANET in multi-hop wireless routing and which node plays as host and router concurrently. Unfortunately, most routing protocols for MANET have drawbacks such as large traffic overhead and long delay time for route discovery due to the network extension. They are major factors of performance degradation of WMN and most researches are focused on them. In this paper, domain-based AODV which is amended AODV to be applied in hybrid WMN is proposed. The proposed scheme divides a hybrid WMN as several domains and performs route discovery by header layer domain. Therefore it can reduce the distance for route discovery as much as average hop count between domain header and member nodes. From the simulation, domain-based AODV was showed slowly increasing delay time due to the network extension.

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.

The wireless mesh network is an emerging technology that provides high quality service to end users as the "last milerdquo of the Internet. Furthermore, multicast communication is a key technology for wireless mesh networks. Multicast provides efficient data distribution among a group of nodes. However, unlike other wireless networks, such as sensor networks and MANETs, where multicast algorithms are designed to be energy efficient and to achieve optimal route discovery among mobile nodes, wireless mesh networks need to maximize throughput. This paper proposes two multicast algorithms: the level channel assignment (LCA) algorithm and the multichannel multicast (MCM) to improve the throughput for multichannel and multi-interface mesh networks. The algorithms build efficient multicast trees by minimizing the number of relay nodes and total hop count distances of the trees. The algorithms use dedicated channel assignment strategies to reduce the interference to improve the network capacity. We also demonstrate that using partially overlapping channels can further diminish the interference. Furthermore, additional interfaces help to increase the bandwidth, and multiple gateways can further shorten the total hop count distance. Simulations show that those algorithms greatly outperform the single-channel multicast algorithm. We also observe that MCM achieves better throughput and shorter delay while LCA can be realized in distributed manner.

Wireless mesh networks are a special kind of ad hoc networks in which most nodes are static. The application purpose of wireless mesh networks is also different than that of ad hoc networks and is focused on broadband access services to the Internet. Recent studies have shown that nodes in a wireless mesh network have to be equipped with several radio interfaces for high performance. However, one of the challenges that still faces high performance wireless mesh networks is the capacity reduction due to interference of wireless links. In this paper, we address the problem of assigning channels to nodes in wireless mesh networks. For this, we propose and study the Cluster Channel Assignment (CCA) approach with the goal of reducing the network interference to increase the overall network performance.

Channel assignment problems in multi-radio wireless mesh networks (WMNs) have been shown to be NP-hard in various scenarios in the literature. By far, most of research efforts have focused on developing efficient approximation algorithms that run reasonably fast and provide good quality channel assignment rather than the optimal one. However, from the practical network design and deployment standpoint, engineers care more about whether it is feasible to optimally assign channels in the simplest way (i.e., exhaustive search), as most of existing commercial WMNs are of small/medium scale. In this paper, we attempt to answer this practical question. We study the complexity of general channel assignment problems with certain basic and common properties. The results show that the complexity in terms of the number of different possible assignments is exponential in the number of wireless links. Furthermore, we estimate the theoretical runtime of determining the optimal channel assignment by exhaustive search and validate it through experiments. We show that, given certain computing power (e.g., an off-the-shelf notebook PC), it is feasible to optimally solve channel assignment problems in small-scale and medium-scale commercial multi-radio WMNs. In other words, approximation algorithms are not needed for most of current commercial WMNs.

We consider the channel assignment problem in wireless mesh networks. Due to the limited number of radio interfaces that each node is equipped with, channel assignment must ensure that the interface constraint is obeyed, i.e., the number of different channels assigned to the links incident on a node must be no greater than the number of interfaces the node is equipped with. However, interface constraint may be one of the causes that hinder the performance of some of the existing heuristics. In this paper, we use simulated annealing to solve the channel assignment problem in wireless mesh networks. We propose two neighbor generating approaches that handle the interface constraint in different ways. The first approach starts with an infeasible random solution, and by using the penalty function technique the solution finally converges to a feasible one. The second approach, on the contrary, allows only feasible solutions to be generated during the simulated annealing process. Simulations are conducted that compare our proposed simulated annealing algorithms together with a tabu-based algorithm under different network traffic scenarios. The results show that our algorithms exhibit lower network interference than the tabu-based algorithm.

Breadth First Search Channel Assignment(BFSCA) is a hybrid channel assignment algorithm that utilize multiple radio interfaces to improve the throughput and minimize the interference within the wireless mesh network and between the mesh network and co-located wireless mesh networks. This new channel assignment scheme allows different nodes in the same network to communicate with each other without causing too much interference to their neighbors. It is introducing Multiradio Conflict Graph(MCG) to model interference in the wireless mesh network. Breadth First Search Channel Assignment considers both the fixed channels (static) and the dynamic channels to reduce interference of the network. BFSCA will increase the network throughput greatly.

Seamless handoff support is an essential issue to ensure continuous communications in wireless mesh networks (WMNs). Due to the existence of multi-hop wireless links, traditional handoff schemes designed for single-hop wireless access networks can hardly guarantee the low handoff latency requirement in WMNs. Existing solutions on reducing the handoff delay in WMNs ignore one important factor for the long handoff delay: the channel access delay of handoff signaling packets over the multi-hop wireless mesh backbone network. Various WMN channel assignment algorithms are designed to optimize the performance of data packets, but they do not address how to resolve the contentions between data packets and handoff signaling packets. In this paper, we propose a novel channel assignment algorithm in WMNs to reduce the channel access delay of handoff signaling packets over multihop wireless links. In addition, handoff solutions under the new channel assignment scheme are proposed. OPNET simulation results show that handoff performance can be improved by our proposed handoff schemes, as compared to existing solutions.