Performance Analysis of IEEE802.11 Wireless Mesh Networks

In a wireless mesh network, the traffic is aggregated at mesh router and most of them forwarded towards the Internet through GW (Internet gateway). Thus easily leads to a bottleneck for network performance at GW. Aimed to this problem ,we firstly treated the GW and mesh router as the alike node equivalently. Then used the logarithm-normal distribution model of shadow affect in wireless communication to design a weighted objective function for guarantee nodepsilas connectivity and coverage, attained the deployment location of the candidate GW; Based of the generated connectivity graph of the network and the constraints of the gateway deployment, consider a heuristic TSP (tree-set partition) algorithm based on degree/weighted to get a good choice of nodes with high throughput and better connectivity act as GW configuration. In conclusion, we validated our ideas and achieved a certain optimization effect under NS2 simulation.

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.

A Wireless Mesh Network (WMN) is a multi-hop network that gains the benefits of low deployment cost, fast access speed, expanded service coverage and large network capacity. However, the multi-hop communication in WMNs limits the throughput capacity due to increased number of packet transmissions. As a result, network coding is a recently emerged paradigm that can enhance the throughput capacity (i.e. network throughput) by minimizing the quantity of network workload and at the same time it ensures the data transfer among all the users. Further, with network coding the transmission effectiveness of a node can be improved by encoding (combining) several packets collectively and verifies whether the coding strategies is satisfied or not. Subsequently, if the coding strategies are satisfied then it transmits only the resultant encoded packet to the desired destination. In other words, network coding can improve the network throughput in WMNs by minimizing the transmission counts needed to transfer several packets to the destination. It should be noted that, while employing network coding in WMNs there are several challenges that should be compensated such as (i) identifying packets that can be combined (encoded) collectively and (ii) integrating the coding strategies in routing protocols. In this paper, we proposed a new mesh routing protocol that integrates network-coding called as Network Coding Aware Routing (Net-CART) protocol. Therefore, to enjoy the whole benefit of network coding a Net-CART protocol uses the innovative routing metric called Code-Aware and Load-Aware Routing Metric. Additionally, to identify numerous ‘coding structures’ and to support number of ‘packet encodings’ an improved set of coding strategies known as Enhanced Universal Coding Strategies is also proposed. The proposed Net-CART protocol comprising an improved set of coding strategies and a new routing-metric considers both the coding-opportunities and “network workload”. The simulation study carried out in wide forms of network configurations showed that Net-CART gives more fairness performances than other protocols.

Wireless Mesh Networks (WMNs) have recently emerged as a technology for next-generation wireless networking. WMNs partially replace wired backbone networks, and it is therefore reasonable to plan carefully radio resource assignment to provide quality guarantees to traffic flows. Directional transmissions allow to reduce radio interference, thus exploiting spatial reuse. Therefore, as a main contribution, in this paper we study the joint routing and scheduling optimization problem in Wireless Mesh Networks where nodes are equipped with directional antennas. To this aim, we assume a Spatial reuse Time Division Multiple Access (STDMA) scheme, a dynamic power control able to vary the emitted power slot-by-slot, and a rate adaptation mechanism that sets transmission rates according to the Signal- to-Interference-and-Noise Ratio (SINR). We provide column generation-based heuristic approaches for the proposed models in a set of realistic-size instances and discuss the impact of different parameters on the network performance. The results show that our schemes increase considerably the total traffic accepted by the network, providing bounds to the achievable performance.

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.

Wireless Mesh Networks (WMNs) have recently gained wide attention as a way to provide Internet connectivity in hard-to-reach areas as well as in big cities. The main problem of such networks is their limited bandwidth availability compared to wired networks. Hence, efficient usage of available communication resources is of crucial importance for WMNs. Peer-to-peer applications, these days, produce a considerable amount of traffic over the Internet. Such applications build their own overlay network by not taking into account the topology and the status of the underlying infrastructure, so causing an inefficient utilization of physical communication resources. This problem is particularly severe for Wireless Mesh Networks. In this paper we propose a cross-layer solution for P2P Bittorrent traffic optimization in WMNs, based on the ALTO (Application Layer Traffic Optimization) Service recently defined by the IETF. Our solution is able to significantly optimize Bittorrent traffic and it does not require any modification to the Bittorrent application. The tests we performed show a reduction of about 27% of download time and a reduction of about 66% of traffic crossing the WMN borders.

ABSTRACTNetwork coding (NC) has showed to be beneficial to improve transmission performance in wireless mesh networks. Random linear coding is usually applied as the default coding schema. However, random linear coding causes significant decoding delay and jitter at receiver. Further, current NC does not support weight assignment to original packets, which is however indispensable for popular applications such as quality of service control and multipath media streaming in wireless mesh networks. Partial network coding (PNC) can largely reduce decoding delay and receiving fluctuation while keeping the benefit of NC. However, PNC does not support weight‐based data replacement and weight assignment to original packets. In this work, we propose weighted partial network coding (WPNC), which is a generalized coding schema of PNC. WPNC inherits all merits of PNC and part of NC. With WPNC, both decoding delay and receiving fluctuation will be reduced as observed in PNC. Also, WPNC is quite suitable for those applications that require weight assignment to original packets. After providing the whole framework of WPNC and thorough theoretical analysis to its performance, we have demonstrated how WPNC can be integrated with quality of service control and multipath routing supported media streaming in wireless mesh networks. Performance of WPNC is inter‐validated by both theoretical analysis and numeric evaluations. Copyright © 2011 John; Wiley & Sons, Ltd.

Wireless Mesh Networks (WMNs) consist of a high-density of hundreds to thousands of mesh routers (MRs) deployed in corporate offices and university campuses. The main purpose of this deployment is to meet user demands for high bandwidth, mobility, and reliability. However, our recent consideration of such networks revealed that they are rarely used at their peak capacity besides the fact that the entire MRS remains active continuously. Thus, during lower traffic periods the energy consumption is the same as in busy hours, while it would be possible to save a large amount of power. Green networking has recently been proposed; consist of rethink how networks are constructed and operated so that not only the cost and performance are taken into consideration but also their energy consumption and carbon footprint. In this paper, we draw attention that a large part of idle MRs results in considerable energy losses. Thousands of WMNs worldwide jointly aggravate this problem, while raising serious worry about the energy wastage that will happen in the future. In response to this problem, we first propose an optimal approach called Optimal Energy Efficiency Management Design (OEEMD) by formulating the problem as a Mixed Integer Linear Program (MILP) model to investigate the power consumption in WMN. As this problem is known to be NP-hard, we then propose an efficient heuristic algorithm called Green Energy Efficiency Management Design (GEEMD) for wireless mesh networks. GEEMD uses a sleep mechanism to power on/off underutilized MRs, based on the traffic load and solar energy generation. For the performance evaluation, we used OEEMD and GEEMD to study the performance of WMN deployment scenario in the university and campus area of Tlemcen city in Algeria over dynamic traffic profiles. Illustrative numerical examples show that, with suitable design parameters, we can efficiently reduce energy consumption in WMN without significantly impacting the network performance.

Developing effective, fairness-preserving optimization algorithms is of considerable importance in systems which serve many users. In this paper we show the results of the threshold accepting procedure applied to extremely difficult problem of fair resource allocation in wireless mesh networks (WMN). The fairness is modeled by allowing preferences with regard to distribution of Internet traffic between network participants. As aggregation operator we utilize weighted ordered weighted averaging (WOWA). In the underlaying optimization problem, the physical medium properties cause strong interference among simultaneously operating node devices, leading to nonlinearities in the mixed-integer pricing subproblem. That is where the threshold accepting procedure is applied. We show that, the threshold accepting heuristic performs much better than the widely utilized simulated annealing algorithm.

In a wireless mesh network (WMN), the traffic is aggregated and forwarded towards the gateways. Strategically placing and connecting the gateways to the wired backbone is critical to the management and efficient operation of a WMN. In this paper, we address the problem of gateways placement, consisting in placing a minimum number of gateways such that quality-of-service (QoS) requirements are satisfied. We propose a polynomial time near-optimal algorithm which recursively computes minimum weighted Dominating Sets (DS), while consistently preserving QoS requirements across iterations. We evaluate the performance of our algorithm using both analysis and simulation, and show that it outperforms other alternative schemes by comparing the number of gateways placed in different scenarios

In wireless mesh networks (WMNs) the meshing architecture, consisting of a grid of mesh routers, provides connectivity services to mesh client nodes. The performance and operability of WMNs largely depends on placement of mesh routers nodes in the geographical area to achieve network connectivity and stability. Thus, finding optimal or near-optimal mesh router nodes placement is crucial to such networks. In this work we propose and evaluate genetic algorithms (GAs) for near-optimally solving the problem. In our approach we seek a two-fold optimization, namely, the maximization of the size of the giant component in the network and the user coverage. The size of the giant component is considered here as a criteria for measuring network connectivity and user coverage as QoS. GAs explore the solution space by means of a population of individuals, which are evaluated, selected, crossed and mutated to reproduce new individuals of better quality. The fitness of individuals is measured with respect to network connectivity and user coverage being the former a primary objective and the later a secondary one. Several genetic operators have been considered in implementing GAs in order to find the configuration that works best for the problem. We have experimentally evaluated the proposed GAs using a benchmark of generated instances varying from small to large size. In order to evaluate the quality of achieved solutions for different possible client distributions, instances have been generated using four distributions of mesh clients (Uniform, Normal, Exponential and Weibull). The experimental results showed the efficiency of the GAs for computing high quality solutions of mesh router nodes placement in WMNs.

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.

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.

In a wireless mesh network, a client station needs to associate with a mesh access point for network access. Conventional association mechanisms assume a high-speed backhaul and only the access link being the bottleneck. This assumption holds for most WLANs, but in wireless mesh networks traffic could be bottlenecked either by the access link or by the bandwidth-limited wireless backhaul. In this paper, we propose an association mechanism for wireless mesh networks to improve stations' end- to-end communication performance with the Internet. A station makes its association decision by jointly considering the quality of the access link between the station and the candidate mesh access point as well as the cost of the multi-hop path from the mesh access point to the gateway. In addition, we design two access link metrics, Contention Aware Expected Transmission Time (CAETT) and Load Aware Expected Transmission Time (LAETT). The main strength of CAETT is incorporating the impact of 802.11 MAC layer contention on the bandwidth sharing among the multi-rate stations. LAETT further captures the traffic load. We evaluate the performance of our system through simulations and demonstrate that the proposed joint association mechanism with the CAETT/LAETT metric can significantly improve the end-to-end performance for wireless mesh networks by up to 60%.

In this letter, we for the first time introduce segment routing (SR) to wireless mesh networks (WMNs) under the primary interference model, and try to obtain the upper bound of maximum network throughput from an online routing perspective. We first propose an SR-enabled WMN (SR-WMN) architecture. We then develop an online primal-dual algorithm with guaranteed worst case performance bound. We finally show via simulation that the proposed solution tends to be close to the optimum by configuring just over half of the wireless mesh routers (WMRs) to support SR.