Wireless Mobile Ad-hoc Networks Research Articles

An efficient cluster-based CDMA/TDMA scheme for wireless mobile ad-hoc networks: A learning automata approach

In this paper, we design a dynamic frame length CDMA/TDMA scheme for clustered wireless ad hoc networks with unknown traffic parameters. In this scheme, the collision-free intra-cluster communications are organized by the cluster-heads using a TDMA scheme, and a CDMA scheme is overlaid on the TDMA to organize the interference-free inter-cluster communications. Therefore, to design such a scheme, we encounter three important problems, namely cluster formation, code assignment, and slot assignment. In this paper, we propose three algorithms to solve the addressed problems based on learning automata. In our scheme, by the proposed clustering algorithm, the wireless hosts are grouped into non-overlapping clusters. Then, by the proposed code assignment algorithm (considering the concept of code spatial reuse), an interference-free code is assigned to each cluster. Finally, by the slot assignment algorithm, each cluster member is assigned a fraction of TDMA frame proportional to its traffic load. The simulation results show that the proposed CDMA/TDMA scheme outperforms the existing methods in terms of almost all metrics of interest, specifically, under bursty traffic conditions.

Density Based Routing Algorithm for Spare/Dense Topologies in Wireless Mobile Ad-Hoc Networks

Problem statement: A Mobile Ad-Hoc Networks (MANETs) operate in environments without infrastructures with an undefined network size. Most routing protocols of Mobile Ad-hoc Networks (MANETs) were studied using open space models where nodes were able to move throughput the entire simulation area. However, a more realistic topology should account for restricted mobility of nodes, such as in an urban city setting where there may be concentrations of nodes within specific areas (such as within buildings) and low density of nodes in other areas (such as in parks and roadways). Consequently, the simulation area should be partitioned into smaller sub-areas with varying densities to model such topologies, called spare/dense topologies. Approach: This study characterized the effect of spare/dense topologies on MANET routing performance and proposes an extension for an existing routing protocol to work in such topologies. Results: The proposed protocol improved the performance of MANETs by reducing the communication overhead incurred during the routing processes by implementing a new broadcast algorithm. The proposed broadcast algorithm was based on the density and connectivity of the nodes and not just the number of nodes. Conclusion: Compared with simple flooding, the proposed algorithm can improve the saved broadcast up to 50% without affecting reach ability, even under conditions of high mobility and density.

Self Umpiring System for Security in Wireless Mobile Ad Hoc Network

A wireless mobile ad hoc network (MANET) is a self-created self-organized and self-administering set of nodes connected via wireless links without the aid of any fixed infrastructure or centralized administrator. In this paper we propose a solution of self-umpiring system that provides security for routing and data forwarding operations. In our system each node in the path from source to destination has dual roles to perform: packet forwarding and umpiring. In the umpiring role, each node in the path closely monitors the behavior of its succeeding node and if any misbehavior is noticed immediately flags off the guilty node. The umpiring system proposed is sufficiently general and can be applied to any networking protocol. For demonstration, we have implemented the self-umpiring system by modifying the popular AODV protocol. Simulation studies show that the proposed system increases throughput by 166.9% with an increase in communication overhead of 13.3% as compared to plain AODV, when 40% of the nodes are malicious and are roaming with a mobility of 20 m/s.

Mobility-based multicast routing algorithm for wireless mobile Ad-hoc networks: A learning automata approach

During the last decades, many studies have been conducted on multicast routing in mobile ad hoc networks (MANET) and a host of algorithms have been proposed. In existing algorithms, the mobility characteristics are assumed to be constant, and so they do not scale well when the mobility parameters are not deterministic. To the best of our knowledge no work has been done on multicast routing when the mobility parameters are stochastic, while in realistic applications these parameters vary with time. In this paper, we propose a mobility-based multicast routing algorithm for wireless MANETs wherein the mobility characteristics are stochastic and unknown. The proposed algorithm estimates the expected relative mobility of each host, by sampling its movement parameters in various epochs, to realistically predict its motion behavior, and takes advantage of the Steiner connected dominating set to form the virtual multicast backbone. To do this, in this paper, a stochastic version of the minimum Steiner connected dominating set problem in weighted network graphs, where the relative mobility of each host is considered as its weight is initially introduced. Then, a distributed learning automata-based algorithm is designed to solve this problem. The designed algorithm is proposed for multicast routing in wireless mobile Ad-hoc networks. The experiments show the superiority of the proposed multicast routing algorithm over the existing methods in terms of the packet delivery ratio, multicast route lifetime, and end-to-end delay. We present a strong convergence theorem in which the convergence of the proposed distributed learning automata-based algorithm to the optimal solution is proved. It is shown that the most stable multicast route is found with a probability as close as to unity by the proper choice of the parameters of the distributed learning automata.

A process calculus for Mobile Ad Hoc Networks

We present the ω -calculus, a process calculus for formally modeling and reasoning about Mobile Ad Hoc Wireless Networks (MANETs) and their protocols. The ω -calculus naturally captures essential characteristics of MANETs, including the ability of a MANET node to broadcast a message to any other node within its physical transmission range (and no others), and to move in and out of the transmission range of other nodes in the network. A key feature of the ω -calculus is the separation of a node’s communication and computational behavior, described by an ω -process, from the description of its physical transmission range, referred to as an ω -process interface. Our main technical results are as follows. We give a formal operational semantics of the ω -calculus in terms of labeled transition systems and show that the state reachability problem is decidable for finite-control ω -processes. We also prove that the ω -calculus is a conservative extension of the π -calculus, and that late bisimulation equivalence (appropriately lifted from the π -calculus to the ω -calculus) is a congruence. Congruence results are also established for a weak version of late bisimulation equivalence, which abstracts away from two types of internal actions: τ -actions, as in the π -calculus, and μ -actions, signaling node movement. We additionally define a symbolic semantics for the ω -calculus extended with the mismatch operator, along with a corresponding notion of symbolic bisimulation equivalence, and establish congruence results for this extension as well. Finally, we illustrate the practical utility of the calculus by developing and analyzing formal models of a leader election protocol for MANETs and the AODV routing protocol.

A reliable QoS aware routing protocol with slot assignment for mobile ad hoc networks

A mobile ad hoc network (MANET) is a collection of mobile hosts that form a temporary network on the fly without using any fixed infrastructure. Recently, the explosive growth in the use of real-time applications on mobile devices has resulted in new challenges to the design of protocols for MANETs. Chief among these challenges to enable real-time applications for MANETs is incorporating support for quality of service (QoS), such as bandwidth constraints. However, MANETs having a high ratio of topology change make routing especially unstable; making stability is an important challenge, especially for routing having a quality of service provision. In this paper, we propose a reliable multi-path QoS routing (RMQR) protocol with a slot assignment scheme. In this scheme, we examine the QoS routing problem associated with searching for a reliable multi-path (or uni-path) QoS route from a source node to a destination node in a MANET. This route must also satisfy certain bandwidth requirements. We determine the route expiration time between two connected mobile nodes using global positioning system (GPS). Then, two parameters, the route expiration time and the number of hops, are used to select a routing path with low latency and high stability. Simulation results show that the proposed RMQR protocol have some outstanding properties when compared with Lin's [Lin C-R. On-demand QoS routing in multihop mobile networks. In: Proceedings of the twentieth annual joint conference of the IEEE computer and communications societies (INFOCOM), vol. 3(22–26), 2001, p. 1735–44], Liao's [Liao W-H, Tseng Y-C, Wang S-L, Sheu J-P. A multi-path QoS routing protocol in a wireless mobile Ad Hoc network. Telecommunication Systems 2002;19(3–4):329–47], and Chen's [Chen Y-S, Tseng Y-C, Sheu J-P, Kuo P-H. An on-demand, link-state, multi-path QoS routing in a wireless mobile Ad-Hoc network. Computer Communications 204;27(1):27–40] protocols.

Ad Hoc Mobile Wireless Networks: Principles, Protocols, and Applications (Sarkar, S. K. et al.; 2008) [Book Review

Mobile wireless ad hoc networks (MANETs) are a rapidly evolving telecommunications technology. Their popularity is connected with their easy deployment and fast configuration. This book is targeted at a variety of readers with different levels of wireless network knowledge. Most of the presented material focuses on different layer protocols for ad hoc networks. It covers practical applications review and cross-layer design aspects, as well as quality of service (QoS), energy, and mobility issues. The book consists of ten chapters, and begins with a short introduction to wireless and ad hoc networks. Each chapter includes a short introduction in which the motivation can be found. At the end of each chapter, final conclusions are given that summarize the presented knowledge. In addition, extensive bibliography sections for deeper reading are attached to the end of each chapter. The book should be attractive to students and graduate students as well as lecturers and network engineers.

Distributed route repair for increasing reliability and reducing control overhead for multicasting in wireless MANET

The Multicast Ad hoc On-Demand Distance Vector (MAODV) routing protocol is proposed for achieving multicast in a Mobile Ad hoc Network (MANET) while reducing bandwidth waste and energy power consumption. In MANET, packets transmission through a multicast tree may always have unreliable links caused by node mobility or lack of energy, and thus significantly degrades the performance. MAODV uses a broadcast-type local repair mechanism to find an alternative route to the multicast tree when some breaks happen on the tree. Although the local repair mechanism provides a specified time-to-live (TTL) to limit the repair range and the hop-count to the group leader, a large number of broadcast-type Route Request (RREQ) messages extensively yields control overhead and requires a large amount of power consumption to send control messages. Thus, this paper proposes a unicast-type multihop local repair protocol for multicast MANETs to recover lost links efficiently while achieving several advantages: increasing network reliability, increasing packet delivery rate, minimizing the number of control messages and reducing repair delay. Moreover, the optimal number of hops used in the multihop neighbor table is analyzed mathematically. Numerical results indicate that the proposed approach outperforms other repair approaches in terms of successful repair rate, control message overhead and packet delivery rate.

ARM: anonymous routing protocol for mobile ad hoc networks

In this paper we describe a novel anonymous on-demand routing protocol for wireless Mobile Ad Hoc Networks (MANETs) that is secure against both nodes that actively participate in the network and a passive global adversary who monitors all network traffic. Finally, we provided a detailed analysis of the privacy offered by hiding routes in limited broadcast groups, and padding messages.

Mobility and reliability modeling for a mobile ad hoc network

The mobile ad hoc wireless network (MAWN) promises to become an ever-present technology with application to a myriad of areas. This networking scheme has its roots in DoD technology, yet, the ability to measure and calculate its reliability is largely absent. This paper describes the unique attributes of the MAWN and how the classical methods for analysis of network reliability must be adjusted. The methods developed acknowledge the dynamic and scalable nature of the new networking scheme along with its absence of infrastructure and remove the need to a priori define a network configuration. The methods rely on a novel modeling approach that recognizes the effects of mobility on the formation of the network's configurations. Hence, this paper proposes a Monte Carlo simulation method that accounts for node mobility, node reliability and node performance in the network's connectivity and resultant network reliability.

Topology control in constant rate mobile ad hoc networks

Topology control is the problem of assigning power levels to the nodes of an ad hoc network so as to create a specified network topology while minimizing the energy consumed by the network nodes. While considerable theoretical attention has been given to the issue of topology control in wireless ad hoc networks, all of that prior work has concerned stationary networks. When the nodes are mobile, there is no algorithm that can guarantee a graph property (such as network connectivity) throughout the node movement. In this paper we study topology control in mobile wireless ad hoc networks (MANETs). We define a mobility model, namely the constant rate mobile network (CRMN) model, in which we assume that the speed and direction of each moving node are known. The goal of topology control under this model is to minimize the maximum power used by any network node in maintaining a specified monotone graph property. Network connectivity is one of the most fundamental monotone properties. Under the CRMN model, we develop general frameworks for solving both the decision version (i.e. for a given value p > 0, will a specified monotone property hold for the network induced by assigning the power value p to every node?) and the optimization version (i.e. find the minimum value p such that the specified monotone property holds for the network induced by assigning the power value p to every node) of the topology control problems. Efficient algorithms for specific monotone properties can be derived from these frameworks. For example, when the monotone property is network connectivity, our algorithms for the decision and optimization versions have running times of O(n 2 log2 n) and O(n 4 log2 n), respectively. Our results represent a step towards the development of efficient and provably good distributed algorithms for topology control problems for MANETs.

Scheme for on-demand route protocol in Ad-hoc networks

On-demand route protocol is widely developed in mobile wireless Ad-hoc networks because of its effectiveness and efficiency. Previous studies have shown limitations of these protocols: in the process of route discovery, broadcast route request (RREQ) messages by flooding may result in excessive redundancy, contention, and collision. In order to relieving broadcast messages, a novel scheme is proposed which is based on the velocities of nodes (VON). Intuition behind VON is that the redundancy of route information and the instability of the route which is composed of high speed of nodes. In VON scheme we use the nodes which have slow speed forward RREQ messages while the nodes which have high speed do not. Simulation results show that VON outperforms the AODV protocol in terms of several metrics, including normalized routing load, end-to-end delay, and packet delivery ratio. The advantages and disadvantages of VON are analyzed, on the based of which, the subsequent investigation work is presented.

Cross Layer PHY-MAC Protocol for Wireless Static and Mobile Ad Hoc Networks

Multihop mobile wireless networks have drawn a lot of attention in recent years thanks to their wide applicability in civil and military environments. Since the existing IEEE 802.11 distributed coordination function (DCF) standard does not provide satisfactory access to the wireless medium in multihop mobile networks, we have designed a cross-layer protocol, (CroSs-layer noise aware power driven MAC (SNAPdMac)), which consists of two parts. The protocol first concentrates on the flexible adjustment of the upper and lower bounds of the contention window (CW) to lower the number of collisions. In addition, it uses a power control scheme, triggered by the medium access control (MAC) layer, to limit the waste of energy and also to decrease the number of collisions. Thanks to a noticeable energy conservation and decrease of the number of collisions, it prolongs significantly the lifetime of the network and delays the death of the first node while increasing both the throughput performance and the sending bit rate/throughput fairness among contending flows.

A Survey of Multicast Routing Protocols for Ad-Hoc Wireless Networks

Many network applications require transmitting the same single copy of data packets concurrently to many destinations, it is called multicasting. Wired and infrastructure-based wireless networks are supported by many multicast routing protocols. But, applying this concept in Mobile Ad hoc wireless NETworks (MANETs) is a big challenge. Ad hoc wireless networks composed of self-organized mobile nodes that can move arbitrarily without any preexisting communication infrastructure base stations. It causes producing dynamic and unpredictable network topology. Many proposals are introduced trying to solve multicast supporting problem in MANETs. In this paper, multicast routing protocols in MANETs that was proposed in recent years will be classified according to different view points such as multicast topology, topology initialization, topology maintenance, core or coreless approach, and dependency on unicast routing protocols.

Maximizing Multicast Communication Lifetime in Wireless Mobile Ad Hoc Networks

We consider the problem of maximizing the lifetime of a given multicast connection in mobile ad hoc networks (MANETs) that use omnidirectional antennas and have limited energy resources. Unlike most multicast algorithms that use centralized greedy algorithms to achieve maximum lifetime in static ad hoc networks, we present two distributed multicast algorithms, i.e., basic energy-efficient multicast (BEEM) and distributed maximum lifetime multicast (DMLM), for the same optimization problem in MANETs. Our distributed algorithms also explore the localized operations to take advantage of the power saving offered by the wireless multicast advantage property in mobile networks. The extensive simulation results have shown that our DMLM algorithm outperforms other proposals in terms of multicast lifetime under different node mobilities.

Simulations of large-scale WiFi-based wireless networks: Interdisciplinary challenges and applications

Wireless Fidelity (WiFi) is the fastest growing wireless technology to date. In addition to providing wire-free connectivity to the Internet WiFi technology also enables mobile devices to connect directly to each other and form highly dynamic wireless adhoc networks. Such distributed networks can be used to perform cooperative communication tasks such ad data routing and information dissemination in the absence of a fixed infrastructure. Furthermore, adhoc grids composed of wirelessly networked portable devices are emerging as a new paradigm in grid computing. In this paper we review computational and algorithmic challenges of high-fidelity simulations of such WiFi-based wireless communication and computing networks, including scalable topology maintenance, mobility modelling, parallelisation and synchronisation. We explore similarities and differences between the simulations of these networks and simulations of interacting many-particle systems, such as molecular dynamics (MD) simulations. We show how the cell linked-list algorithm which we have adapted from our MD simulations can be used to greatly improve the computational performance of wireless network simulators in the presence of mobility, and illustrate with an example from our simulation studies of worm attacks on mobile wireless adhoc networks.

Optimal design of cluster-based ad-hoc networks using probabilistic solution discovery

The reliability of ad-hoc networks is gaining popularity in two areas: as a topic of academic interest and as a key performance parameter for defense systems employing this type of network. The ad-hoc network is dynamic and scalable and these descriptions are what attract its users. However, these descriptions are also synonymous for undefined and unpredictable when considering the impacts to the reliability of the system. The configuration of an ad-hoc network changes continuously and this fact implies that no single mathematical expression or graphical depiction can describe the system reliability-wise. Previous research has used mobility and stochastic models to address this challenge successfully. In this paper, the authors leverage the stochastic approach and build upon it a probabilistic solution discovery (PSD) algorithm to optimize the topology for a cluster-based mobile ad-hoc wireless network (MAWN). Specifically, the membership of nodes within the back-bone network or networks will be assigned in such as way as to maximize reliability subject to a constraint on cost. The constraint may also be considered as a non-monetary cost, such as weight, volume, power, or the like. When a cost is assigned to each component, a maximum cost threshold is assigned to the network, and the method is run; the result is an optimized allocation of the radios enabling back-bone network(s) to provide the most reliable network possible without exceeding the allowable cost. The method is intended for use directly as part of the architectural design process of a cluster-based MAWN to efficiently determine an optimal or near-optimal design solution. It is capable of optimizing the topology based upon all-terminal reliability (ATR), all-operating terminal reliability (AoTR), or two-terminal reliability (2TR).

Reliability of capacitated mobile ad hoc networks

Ad hoc networking is used for the flexibility it provides. Its dynamic topology allows employment of the mobile ad hoc wireless network (MAWN) without groundwork because no infrastructure is required. However, these distinctive attributes of ad hoc networking do not conform to a key assumption under which most existing network reliability methods are founded; that network connectivity is known a priori. Therefore, ad hoc networking requires new network reliability assessment methods. Based on the unique characteristics of ad hoc networks, previous research has been focused on the development of methods that consider the probabilistic formation of the network topology and how to embed mobility models within a reliability approximation technique. This paper provides further advances in the area of MAWN reliability by removing the previous assumptions that link status is solely determined by node separation distance, resulting in a binary link behaviour. This paper proposes the use of a mathematical model for link capacity combined with a Monte Carlo simulation of the demand upon each link and each node's mobility. This new extension provides the ability to consider additional design parameters and their impact on reliability.

A formal validation methodology for MANET routing protocols based on nodes’ self similarity

Conformance testing for ad hoc routing protocols is crucial to the reliability of Wireless Mobile Ad Hoc Networks. Most of the works related to the validation of such protocols are based on simulation and emulation analysis of simulated/emulated implementations without taking into account formal specifications. However, for many reasons, it has often been shown that the results obtained from simulator studies are far from the real case studies. In this paper, we propose a new conformance testing methodology dedicated to the validation of MANET routing protocols, especially Dynamic Source Routing. After generating test sequences from the formal model, the main issue is to execute them. There exist many techniques in wired systems, but several MANET inherent constraints lead to cope with the diverse mobility patterns and the topological changes. Therefore, a nodes’ self similarity approach is introduced as well a specific testing architecture dealing with unexpected and unpredictable topology and messages. Interesting results have been provided as illustrated through experiments.

Reliability analysis of cluster-based ad-hoc networks

The mobile ad-hoc wireless network (MAWN) is a new and emerging network scheme that is being employed in a variety of applications. The MAWN varies from traditional networks because it is a self-forming and dynamic network. The MAWN is free of infrastructure and, as such, only the mobile nodes comprise the network. Pairs of nodes communicate either directly or through other nodes. To do so, each node acts, in turn, as a source, destination, and relay of messages. The virtue of a MAWN is the flexibility this provides; however, the challenge for reliability analyses is also brought about by this unique feature. The variability and volatility of the MAWN configuration makes typical reliability methods (e.g. reliability block diagram) inappropriate because no single structure or configuration represents all manifestations of a MAWN. For this reason, new methods are being developed to analyze the reliability of this new networking technology. New published methods adapt to this feature by treating the configuration probabilistically or by inclusion of embedded mobility models. This paper joins both methods together and expands upon these works by modifying the problem formulation to address the reliability analysis of a cluster-based MAWN. The cluster-based MAWN is deployed in applications with constraints on networking resources such as bandwidth and energy. This paper presents the problem's formulation, a discussion of applicable reliability metrics for the MAWN, and illustration of a Monte Carlo simulation method through the analysis of several example networks.