The reliability of the mobile ad hoc network (MANET) is receiving increasing attention. Previous works are mainly focused on the connectivity reliability of the MANET; however, its performance reliability has not been considered. In the MANET, the paths connecting two nodes are prone to continuous changes due to the mobility of nodes, which can result in a huge uncertainty on the transmission performance. Thus it is necessary to research the evaluation method of the performance reliability of the MANET. In this study, the transmission reliability is defined to measure the reliability of the transmission performance of the MANET. The impact of interference on the transmission reliability is considered. The topology optimization of the MANET is studied based on the transmission reliability, and genetic algorithm is adopted to solve the optimization problem. In the numerical example, the effects of the involved parameters on the transmission reliability are discussed, and some applicable conditions of the optimal design are analyzed for practical applications.

Introduction

The mobile ad hoc network (MANET) is an emerging communication technology [1]. Its flexible and easy deployment has attracted different application areas, such as military [2], disaster recovery [3] and vehicular communication [4]. In simple terms, the MANET is an autonomous wireless network without fixed infrastructure, and it consists of nodes which can move dynamically [5]. A link (or called a hop) between two nodes exists if both nodes are in the communication range of each other. Multi-hop communication is popularly applied in the MANET to increase the overall network capacity and performance [6]. A multi-hop path connecting two nodes can be established by taking other nodes as relay nodes. Network reliability refers to the probability that the function of a network can meet the use requirement, and it is an important index to weigh network performance [7]. Network reliability has been researched in many fields, such as communication [8], transportation [9] and electric power [10], to design new systems or improve existing systems. The connectivity reliability and the performance reliability are two branches of network reliability, and both of them are important for the reliability evaluation of networks [11]. The connectivity reliability mainly studies the topology structure of networks, and it is defined as the probability that a certain set of nodes in a network are connected [12]. The performance reliability is related to network performance, such as transmission delay for a communication network, and it is defined as the probability that the performance of a network can meet the use requirement [11]. Recently, the reliability of the MANET is receiving increasing attention. Most of the previous works are focused on the connectivity reliability. Such studies include Cook and Ramirez-Marquez [13-18], Padmavathy and Chaturvedi [19-21], Kharbash and Wang [22], Chen et al. [23], Wang [24], etc. However, for the MANET, it is untrue that a high connectivity reliability can guarantee an excellent transmission performance, and it is one-sided to evaluate the reliability by only considering the connectivity reliability [11]. In the MANET, the paths connecting two nodes are prone to continuous changes due to the mobility of nodes, which can result in a huge uncertainty on the transmission performance [25]. The connectivity reliability measures the ability of the MANET to maintain the connectivity of nodes. Two nodes are connected as long as there are paths between them. However, the connectivity reliability cannot reflect the effect of the change of paths on the transmission performance. If the paths connecting two nodes vary frequently, communication interruptions may often occur between the nodes, and the transmission performance may be unsatisfactory. Therefore, it is needed to consider the performance reliability of the MANET.