Self-Reconfigurable Wireless Mesh Networks

Self-Reconfigurable Wireless Mesh Networks

Abstract

During their lifetime, multi-hop wireless mesh networks (WMNs) experience frequent link failures caused by channel interference, dynamic obstacles and/or applications’ bandwidth demands. These failures cause severe performance degradation in WMNs or require expensive, manual network management for their real-time recovery. This paper presents an Autonomous network Reconfiguration System (ARS) that enables a multi-radio WMN to autonomously recover from local link failures to preserve network performance. By using channel and radio diversities in WMNs, ARS generates necessary changes in local radio and channel assignments in order to recover from failures. Next, based on the thus-generated configuration changes, the system cooperatively reconfigures network settings among local mesh routers. ARS has been implemented and evaluated extensively on our IEEE 802.11-based WMN test-bed as well as through ns-2-based simulation. Our evaluation results show that ARS outperforms existing failure-recovery schemes in improving channel-efficiency by more than 90%and in the ability of meeting the applications’ bandwidth demands by an average of 200%.

Architecture

Algorithm

ARS’s planning algorithm:

This algorithm describes the operation of ARS. First, ARS in every mesh node monitors the quality of its outgoing wireless links at every tm (e.g., 10 sec) and reports the results to a gateway via a management message. Second, once it detects a link failure(s), ARS in the detector node(s) triggers the formation of a group among local mesh routers that use a faulty channel, and one of the group members is elected as a leader using the well-known bully algorithm, for coordinating the reconfiguration. Third, the leader node sends planning request message to a gateway. Then, the gateway synchronizes the planning requests if there are multiples requests—and generates a reconfiguration plan for the request. Fourth, the gateway sends a reconfiguration plan to the leader node and the group members. Finally, all nodes in the group execute the corresponding configuration changes, if any, and resolve the group. We assume that during the formation and reconfiguration, all messages are reliably delivered via a routing protocol and per-hop retransmission timer.

Existing System

First, resource-allocation algorithms can provide (theoretical) guidelines for initial network resource planning. However, even though their approach provides a comprehensive and optimal network configuration plan, they often require “global” configuration changes, which are undesirable in case of frequent local link failures. Next, a greedy channel-assignment algorithm can reduce the requirement of network changes by changing settings of only the faulty link(s). However, this greedy change might not be able to realize full improvements, which can only be achieved by considering configurations of neighboring mesh routers in addition to the faulty link(s). Third, fault-tolerant routing protocols, such as local re-routing or multi-path routing, can be adopted to use network-level path diversity for avoiding the faulty links. However, they rely on detour paths or redundant transmissions, which may require more network resources than link-level network reconfiguration.

Disadvantages:

1. Can not avoid propagation of QoS failures to neighboring links

                        2. Unsuitable for dynamic network reconfiguration

Proposed System

To overcome the above limitations, we propose an Autonomous Network Reconfiguration System (ARS) that allows a multi-radio WMN to autonomously reconfigure its local network settings—channel, radio, and route assignment—for real-time recovery from link failures. In its core, ARS is equipped with a reconfiguration planning algorithm that identifies local configuration changes for the recovery, while minimizing changes of healthy network settings. Briefly, ARS first searches for feasible local configuration changes available around a faulty area, based on current channel and radio associations. Then, by imposing current network settings as constraints, ARS identifies reconfiguration plans that require the minimum number of changes for the healthy network settings. It detects a long-term (lasting for weeks or months) failures, network-wide planning algorithms can be used. Note that hardware failures (e.g., node crashes) or broadband-channel failures (e.g., jamming)

Advantages:

1.                             Public safety, environment monitoring and city-wide wireless Internet services

2.                             Avoid propagation of QoS failures to neighboring links(or ‘ripple effects’).

       Modules:

1. Multi-radio WMN

2. Link-Failure Detection

3. Leader Node

           4. Network Planner

          1. Multi-radio WMN:

A network is assumed to consist of mesh nodes, IEEE 802.11-based wireless links, and one control gateway. Each mesh node is equipped with n radios, and each radio’s channel and link assignments are initially made by using global channel/link assignment algorithms.

2. Link-Failure Detection:

ARS in every mesh node monitors the quality of its outgoing wireless links at every tm (e.g., 10 sec) and reports the results to a gateway via a management message. Second, once it detects a link failure(s), ARS in the detector node(s) triggers the formation of a group among local mesh routers that use a faulty channel, and one of the group members is elected as a leader and coordinating the reconfiguration.

           3. Leader Node:

          The leader node sends a planning-request message to a gateway. If any link is failure group members send request to the particular leader after that the leader node send request to the gateway.

4. Network Planner:

It generates reconfiguration plans only in a gateway node. Network planner plans the diversity path for avoiding the faulty links. Then, the gateway synchronizes the planning requests—if there are multiples requests—and generates a reconfiguration plan for the request. Fourth, the gateway sends a reconfiguration plan to the leader node and the group members. Finally, all nodes in the group execute the corresponding configuration changes, if any, and resolve the group.

HARDWARE & SOFTWARE REQUIREMENTS:

 HARDWARE REQUIREMENTS: 

·                     System                                   :               Pentium IV 2.4 GHz.

·                     Hard Disk                             :               40 GB.

·                     Floppy Drive                        :               1.44 Mb.

·                     Monitor                                 :               15 VGA Color.

·                     Mouse                                    :               Logitech.

·                     Ram                                        :               512 MB.

  SOFTWARE REQUIREMENTS: 

·                     Operating system                :               Windows XP Professional.

·                     Coding Language                :               C#.NET