Simulation of Mobile Ad-Hoc Wireless Algorithm Base on Ant Colony
1.1 Background of the study
The term routing in computer networking refers to selecting paths in a computer network along which to send data. Routing is the task of directing data flow from source to destination maximizing network performance. It involves the passing of logically addressed packets from their source toward their ultimate destination through intermediary nodes called routers.
There are two variations of wireless networks: infrastructured and infrastructure less. In an infrastructure network, a node can connect to a nearest central gateway known as the base station. A base station is a fixed and acts as router to other nodes. Communications among nodes can only be achieved through these fixed gateways. Typical applications of this type include mobile phones services, wireless local networks (WLANs). On the other hand infrastructureless or ad-hoc networks have no fixed routers. All nodes of this type of network act as routers. Applications of ad-hoc network include, for example, meetings or conventions where people wish to share information quickly, data acquisition operations in remote and inhospitable terrains, emergency search-and-rescue operations, war fields etc.
In recent years there has been an increasing interest in Mobile Ad–Hoc Networks (MANETs) (Di Caro, G., Ducatelle, F., & Gambardella, L. M., 2004). In this kind of networks, all nodes are mobile, and they communicate with each other via wireless connection. There is no fixed infrastructure. All nodes are equal and there is no centralized control. There are no designated routers, all nodes can serve as routers for each other, and data packets are forwarded from node to node in a multi-hop fashion.
Routing is particularly difficult in MANETs. Due to the mobility of the nodes, the topology of the network changes constantly and paths which were initially efficient can quickly become inefficient or even infeasible. This means that routing information should be updated more regularly than in wired networks, so that in principle more routing control packets are needed. However, this is a problem in MANETs, since the bandwidth of the wireless medium is very limited, and medium is shared, nodes can only send or receive data if no other node is sending in their neighbourhood. The access to the shared channel is controlled by protocols at the Medium Access Control layer (MAC), such as ANSI/IEEE 802.11 DCF (the most commonly used in MANETs), which in their turn create extra overhead.
1.2 Statement of the problem
Mobile devices are now being equipped with wireless connectivity as standard (Bailey, 2004) allowing for, potentially, quick, easy, temporary connections to be made between them. This allows for the creation of a network known as an ad-hoc network. With the recent technological advance in wireless communication and the increasing popularity of portable computing devices, wireless and mobile ad-hoc networks are expected to play increasingly important role in future civilian and military settings where wireless access to wired backbone is either ineffective or impossible.
Mobile ad-hoc networks (MANETs) are composed of a set of stations (nodes) communicating though wireless channels, without any fixed backbone support (Boukerche, 2008). However, frequent topology changes caused by node mobility make routing in wireless ad-hoc networks a challenging problem. In addition, limited capabilities of mobile stations require a control on node congestion due to message forwarding and limited battery consumption. Mobility of mobile hosts introduces also new challenging problems that were not encountered in the design and implementation of conventional wireless and wired networks. For example, data communication in a MANET differs from that of wired networks in different aspects. For example, the wireless communication medium does not have a foreseeable behaviour as in a wired channel. On the contrary, the wireless communication medium has variable and unpredictable characteristics. The signal strength and propagation delay may vary with respect to time and environment where the mobile nodes are. Unlike a wired network, the wireless medium is a broadcast medium, that is, all nodes in the transmission range of a transmitting device can receive a message.
A critical and challenging problem of mobile ad-hoc networking and computing is how to fully cope with the special characteristics of the wireless and mobile ad-hoc environment, make balanced used of computation and communication resources, and take advantage of and support the user’s mobility. Most of the available literature in this emerging technology concentrates on physical and networking aspects of the subject. However, in most of the these studies, they have neglected the description of the fundamental design of distributed algorithms and have not discussed how to apply them to wireless and mobile ad-hoc and network setting environments.
1.3 Aim and Objectives
The specific challenges and possible applications of MANETs have made this a very popular research area, and a lot of routing algorithms have been proposed.
This research work focuses on implementing a routing algorithm suitable for ad-hoc networks. The routing protocol has to discover available network routes to destinations when needed, dynamically re-route around broken or heavily loaded links to maintain the desired quality of service.
The objective of this research work is to develop a routing algorithm that will support user’s mobility in an ad-hoc wireless network.
The specific objectives are to:
- To modify the already existing computational model that will maintain the desired quality of service during routing from source to destination in wireless ad-hoc networks,
- Simulate the model formulated in (i) above and
- Assess the performance of the proposed model.
1.4 Significance of the study
Routing algorithm is an approach that is carried out on a regular basis. It cannot be left out of discussion with the fact that application of networking either wired or wireless has taken over the society. Every day we look for faster way to make things work out, like finding the shortest route to reach a destination, minimize cost of materials, connect networks easily, etc. as a result the act of routing algorithm cannot be overlooked in life. In the world of computing, programmers have implemented several routing algorithms that will help minimize and save time in reaching a destination. Application and comparing the efficiencies of these algorithms helps to choose which is preferred in solving a particular problem.
Routing algorithms are of different types which include both wired and wireless with various importance. The major significance of this research work is to modify the routing algorithm using a wireless network base on ant colony to make it more efficient and effective.
1.5 Scope of the study
There are many routing algorithms that exist but differ in terms of their performance. Some important and well known routing algorithms are non-adaptive and adaptive. Our focus in this research work is however limited to adaptive algorithm which is also known as dynamic routing.
This algorithm can be applied to solve many problems; shortest path problems and many more. Our focus in this research work is it application in mobile wireless routing algorithm.
1.6 Definition of terms
Ad hoc: is a Latin phrase meaning “for this”. In English, it generally signifies a solution designed for a specific problem or task, non-generalizable, and not intended to be able to be adapted to other purposes
An algorithm: is an effective method that can be expressed within a finite amount of space and time and in a well-defined formal language for calculating a function. Starting from an initial state and initial input (perhaps empty), the instructions describe a computation that, when executed, proceeds through a finite number of well-defined successive states, eventually producing “output” and terminating at a final ending state.
Wireless: is the transfer of information or power between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio waves. With radio waves distances can be short, such as a few meters for Bluetooth or as far as millions of kilometres for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking.
Network: in computing, is a group of two or more devices that can communicates. In practice, a network is comprised of a number of different computer systems connected by physical and/or wireless connections. The scale can range from a single PC sharing out basic peripherals to massive data centres located around the World, to the Internet itself. Regardless of scope, all networks allow computers and/or individuals to share information and resources.