Efficient self-organized backbone formation in mobile ad hoc networks (MANETs)

Abstract

In wireless networks other than source and destination nodes, intermediate nodes play a major role for routing and other control transfer functions. Hence the network must be formed by self-organized intermediate nodes. This feature of the node is also used to protect the network from uncertainties like link, node failures. The main objective of this paper is to give the characteristics of intermediate nodes; how they support the quality of service issues. Existing research work in this area mainly concentrates on backbone construction and there is no solution for self-organized backbone formation. A new distributed localized algorithm is proposed to construct and maintain the backbone network named as SOB-T or M (self-organized backbone- tree or mark), which means that tree or marking scheme are used to construct the backbone network. The QoS parameters like throughput, delay and number of control messages are analyzed in this paper.

Introduction

Quality of Service in an ad hoc environment has been widely recognized as a challenging problem. Characteristics of ad hoc networks such as mobility, dynamics of the environment and uncertainty of resource availability makes provisioning of QoS guarantees difficult. The performance of MANET categorized by two types based on quality of service: (1) Statefull – each node maintains state information about the traffic flow and connectivity. (2) Stateless – does not maintain the state information, which is scalable in wireless networks. The proposed work self-organized backbone also fall under partially statefull QoS type i.e. only the backbone node maintains state information based on demand. State information’s are maintained by the backbones during the request made by other nodes i.e. a node wish to connect or leave the backbone or require high bandwidth link.

Many routing protocols are developed in the last two decades, all the routing mechanisms are based on the assumption that each node receives the information in one interface and forwards to other interface. Only the intermediate nodes perform these functions, where as the origin or source nodes perform the route finding process in the initial stage. Hence source and destination must rely on intermediate nodes for route finding, data transfer and acknowledgement process. These three functions are involved in the basic packet switching methods like virtual circuit and data gram approaches. From this point of view priority or importance must be given to intermediate nodes, and the routing protocol design should concentrate on these nodes. An intermediate node must have the following characteristics: (1) freedom from flooding (broad cast storm problem), (2) limited power they can harvest or store, (3) ability to cope with node failures, (4) sustain during dynamic network topology, (5) predict communication failures, and (6) identify the duplicate packets.

A simple protocol design includes the header, payload and error detection fields in the wireless routing domain. In addition number of hop count is also considered for higher layer protocols like transmission control protocol (TCP) for setting the discard eligibility of the packet. A basic protocol design must be aware of the fundamental looping problem and sustain in node and link failure situation. Self-organized backbone network is defined as the backbone or sink nodes form a network, which should carry other node information during the routing process. The illustration of self-organized backbone nodes and networks in wireless domain is given in Fig. 1. From the figure, it is understood that the self-organized backbone node has high transmission power and are able to connect the backbone and normal nodes in one hop during the network failure conditions.

The processes like computing, table updations are account able factor for lifetime of the node in wireless networks. Each node must work with their own desire, conserve their resources and work in self-organized manner in MANET. For energy consuming, centralized approaches like cluster based routing not suitable because the whole network is based on the clusters as well as their coverage in mobile ad hoc networks. The two fundamental ideas: (1) selfish behavior of each node, (2) coverage of the node in ad hoc network motivated by us to develop this proposed work. To implement this approach all the nodes are permitted to work independently. Several algorithms [6], [7], [9] have been proposed to create backbone constructions. These algorithms deal with how to reduce the backbone in wireless networks and do not motivate the selfish behavior of the nodes. Modeling systems based on a selfish algorithm are developed to improve the performance of the ad hoc network, and do not guarantee the global solutions. The objective of the research work is more practical importance and has been underscored in [11], [12], [19] which provide excellent motivation to consider self-organization behavior of wireless networks.

Self-organized backbone set is a subset of connected dominating set. The CDS approaches follow the spanning tree or marking process. Maintaining the dominating set for a long duration is the main objective of the researchers in backbone concept. Self-organized backbones are created from the dominating set whenever the network needs to maintain the mobility. Complexity of the proposed approach is normally in logarithmic values only because the self-organized backbone involve in control transfer, where as CDS follows O (n²) complexity. The comparison of these two methods is given in Table 1.

The remaining of the paper is organized as follows: Section 2 describes the related work on the backbone construction with notations. Section 3, describes the formation of backbones. The selfish behavior of backbone node is given in Section 4 with tree structure. To illustrate the performance of the proposed network Section 5 is included with simulation results. Section 6, concludes the paper.