Delay In Wireless Mesh Networks Research Articles

Performance Evaluation of VoIP Codecs over Network Coding in Wireless Mesh Networks

Voice over Internet protocol (VoIP) is used for transmitting voice signals in a packet-switched Internet protocol (IP) networks in real time. For transmitting voice over a wireless mesh networks (WMNs), the analog voice signal has to be digitalized, encoded, and packetized. Codecs based on different Quality of Service (QoS) requirements are used. One of the main QoS requirements is that packets are transmitted through the network in real time; one-way transmission time or End-to-End (ETE) packet delay, and packet delay variation or jitter have to be lower than thresholds. ETE delay depends on various parameters; among them is also network delay. Various mechanisms are used to lower the network delay in WMNs. A promising mechanism, for improving the performance of streaming services such as the case also in VoIP, is network coding. In this paper, we evaluate the benefits of using wireless network coding for VoIP in WMNs. Network coding procedure in combination with various VoIP codecs is used to observe the impact on network delay and jitter of the VoIP application. The simulation results show that network coding can decrease network delay and jitter. Moreover, results show that network coding benefits are codec dependent.

A Dynamic Channel Selection Algorithm of Data Forwarding in Wireless Mesh Networks

Wireless Mesh Networks (WMNs) is an emerging technology in networking, in which the devices (nodes) are configured with multi-radios, making the overall capacity improved significantly. Nodes avoid interference with each other by tuning to different channels of the spectrum space. When a node intends to communicate to other nodes, especially a node far away from it with multiple hops, it is critical to find the channel with largest bandwidth to forward the packet. A dynamic channel selection algorithm is presented in this article, by which each node is able to find its next hop based on the criteria of possible largest channel bandwidth to carry out the forwarding. The novel idea of our approach is that only three past numerical data are kept by each node, and then it is able to calculate the potential bandwidth capacity and continue the most efficient forwarding. Simulations experiments were conducted and the results demonstrated that our mechanism outperforms peer approaches in terms of bandwidth capabilities and delay in Wireless Mesh Networks.

Secure handoff technique with reduced authentication delay in wireless mesh network

The aim of manuscript is to propose a secure handoff procedure by generating the tickets for the mesh clients which are divided into different zones of mesh routers according to their communication range. An authentication server looks over the entire network after a specific interval of time and is responsible for generating and updating the corresponding tickets of clients according to their zonal routers range. Whenever a mesh client enters into the range of another domain, to access the services from foreign mesh routers, roaming client has to prove its authenticity to the corresponding zonal router. Each mesh router stores the ticket of its zonal mesh client issued from authentication server and validates the roaming client by matching the ticket. The proposed mechanism reduces the issue of storage overhead and security threats at mesh client as all the tickets are stored in authentication server database and are issued upon the request. The proposed technique is validated over authentication delay and different probabilistic scenarios of authentication and is proved legitimate by discussing an empirical study against reported literature.

Secure handoff technique with reduced authentication delay in wireless mesh network

Secure handoff technique with reduced authentication delay in wireless mesh network

A Review on Methodologies for CapacityImprovement with Minimum Delay in WMN

In recent years there is explosive growth towards wireless broadband technologies which accelerating the need to design an efficient “last mile” access network in a cost-effective manner. Wireless Mesh Network (WMN) is emerging as promising technology for many useful applications. Over the past decade the size, cost and power requirements of radios has declined, enabling multiple radios to be contained within a single mesh node, thus allowing for greater modularity each can handle multiple frequency bands and support a variety of functions as needed such as client access, packet forwarding and scanning with minimum relays between nodes in wireless network. In order to making cost –efficient network different routing protocols are proposed. In this paper after analysing the different methodologies we use improved methodology that will not only find the shortest path but also making an efficient network by minimizing the delay from source to destination nodes in wireless network.

DCNC: throughput maximization via delay controlled network coding for wireless mesh networks

AbstractNetwork coding (NC) can greatly improve the performance of wireless mesh networks (WMNs) in terms of throughput and reliability, and so on. However, NC generally performs a batch‐based transmission scheme, the main drawback of this scheme is the inevitable increase in average packet delay, that is, a large batch size may achieve higher throughput but also induce larger average packet delay. In this work, we put our focus on the tradeoff between the average throughput and packet delay; in particular, our ultimate goal is to maximize the throughput for real‐time traffic under the premise of diversified and time‐varying delay requirements. To tackle this problem, we propose DCNC, a delay controlled network coding protocol, which can improve the throughput for real‐time traffic by dynamically controlling the delay in WMNs. To define an appropriate control foundation, we first build up a delay prediction model to capture the relationship between the average packet delay and the encoding batch size. Then, we design a novel freedom‐based feedback scheme to efficiently reflect the reception of receivers in a reliable way. Based on the predicted delay and current reception status, DCNC utilizes the continuous encoding batch size adjustment to control delay and further improve the throughput. Extensive simulations show that, when faced with the diversified and time‐varying delay requirements, DCNC can constantly fulfill the delay requirements, for example, achieving over 95% efficient packet delivery ratio (EPDR) in all instances under good channel quality, and also obtains higher throughput than the state‐of‐art protocol. Copyright © 2014 John Wiley & Sons, Ltd.

A Data Rate and Concurrency Balanced Approach for Broadcast in Wireless Mesh Networks

In this paper, we address the problem of joint power control and scheduling for minimizing broadcast delay in wireless mesh networks. Given a set of mesh routers and a routing tree, we aim to assign power for relay nodes and compute an optimal transmission schedule such that the total delay for a packet broadcast from the root to all the routers is minimized. We consider rate adaptation in our scheme. This is a difficult issue. High power enables high data rate but causes high interference, whereas low power allows more concurrent transmissions at the expense of data rate. We study the tradeoff between data rate and concurrency and propose a balanced method. We introduce a metric called standard deviation of average remaining broadcast time to determine the priority of the two parameters. When this metric is greater than a threshold, the nodes will take the data-rate-first approach to increase the data rate; otherwise, the concurrency-first approach will be used to increase the number of concurrent transmissions. Theoretical analysis is given to show the upper and lower bounds of this metric. Simulations have demonstrated that our proposed method can reduce the broadcast delay significantly as compared with existing methods.

Adjusting the TCP Sending Rate and Retransmissions after Retransmission Timeouts Based on One-Way Queuing Delay in Wireless Mesh Network

Wireless Mesh Network (WMN) is regarded as a viable solution to provide broadband Internet access flexibly and cost efficiently. Improving the performance of Transmission Control Protocol (TCP) in WMNs is an active research area in the networking community. The existing solutions proposed for improving the TCP performance has concentrated on differentiating the DATA packet drops in the forward direction induced by both network congestion as well as transmission errors. However, the recent studies show that in WMNs packet drops occur not only in the forward direction but also in the reverse direction particularly due to hidden terminal, hidden capture terminal, link asymmetry etc. The loss of ACK packets in the reverse direction cause frequent retransmission timeouts subject to needless retransmissions and unnecessary slowing down the growth of congestion window, which causes the performance degradation of TCP. In this paper, we introduce a sender side TCP algorithm, called detection of packet loss (DPL), which is capable to distinguish the type of packet drops either DATA or ACKs caused by transmission errors as well as network congestion based on one-way queuing delay and react accordingly. To justify our contributions, we implement DPL in Qualnet simulator and compare its performance against existing TCP solutions via extensive simulations. Our simulation results show that the proposed algorithm can accurately distinguish the type of packet drops whether it is a DATA or ACK caused by transmission error or congestion and can significantly improve the performance under a wide range of scenarios in WMNs.

A Channel Splitting Strategy for Reducing Handoff Delay in Internet-Based Wireless Mesh Networks

Seamless intergateway handoff support is an essential issue to ensure continuous communications in Internet-based wireless mesh networks (WMNs). Due to the existence of multihop wireless links, traditional handoff schemes designed for single-hop wireless access networks can hardly guarantee the low handoff latency requirement in multihop 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 multihop wireless mesh backbone network. In this paper, we address the seamless intergateway handoff issue in Internet-based WMNs from a different perspective and propose a channel splitting strategy to reduce the channel access delay of handoff signaling packets over multihop wireless links. The handoff procedures of two scenarios when a mobile node has one or two transceivers are designed, and two transmission strategies for scheduling the delivery of handoff signaling packets are proposed. Simulation results show that by using the proposed channel splitting strategy, the handoff delay requirement in WMNs can be guaranteed, regardless of the background data traffic, and the average channel utilization can also be improved.

A Multichannel TDMA MAC Protocol to Reduce End-to-End Delay in Wireless Mesh Networks

Supporting QoS over multihop wireless mesh networks is difficult because end-to-end delay increases quickly with the increasing number of hops. This paper introduces a novel multichannel time-division multiple-access media access control (McTMAC) protocol that can help to efficiently reduce delay over multihop networks. Performance evaluation results demonstrate that McTMAC outperforms existing alternative protocols. The max-delay can be reduced by as much as 60% by using McTMAC.

Location-Dependent Throughput and Delay in Wireless Mesh Networks

In this paper, we model the location-dependent throughput and delay in wireless mesh networks. We analyze the packet-arrival and the packet-departure rates for the forwarding queues at relaying nodes and then derive the per-user throughputs and packet delays experienced by nodes at different hop-count distances from the gateway. Based on this analytical model, we propose two network design strategies to provide fair resource sharing and minimize the end-to-end delay in wireless mesh networks. We then conduct simulations to validate the correctness of our analytical model and evaluate the performance of the proposed network design strategies. The results show that our analytical framework can accurately model the location-dependent throughput and delay in wireless mesh networks and that our proposed strategies effectively and efficiently provide fair throughputs for nodes and reduce the end-to-end packet delay. This paper not only provides a framework for studying the performance of wireless mesh networks but also gives insights into the network design strategy for wireless mesh networks.