Study of capacity region and minimum energy of delay‐tolerant unicast mobile ad hoc networks using cell‐partitioned model

Capacity region and minimum energy function for a variety of delay‐tolerant mobile unicast ad hoc networks are studied by using a cell‐partitioned model. First, theorems about analytical expressions of network capacity and upper bound of minimum energy function are proposed and proved. Algorithm aiming at maximizing capacity and minimizing energy cost is presented and analyzed by Lyapunov drift method. Second, these two theorems are applied to several types of ad hoc networks. Expressions of network capacity and minimum energy function are obtained. Third, capacity property of a type of hybrid ad hoc networks is analyzed in detail. Relationship among limitation of capacity, node density, and coverage of base stations are investigated. Numerical analysis and simulation are carried out. Copyright © 2015 John Wiley & Sons, Ltd.     

An optimised resource aware approach to information collection in ad hoc networks

In ad hoc networks there is a need for all-to-one protocols that allow for information collection or “sensing” of the state of an ad hoc network and the nodes that comprise it. Such protocols may be used for service discovery, auto-configuration, network management, topology discovery or reliable flooding. There is a parallel between this type of sensing in ad hoc networks and that of sensor networks. However, ad hoc networks and sensor networks differ in their application, construction, characteristics and constraints. The main priority of sensor networks is for the flow of data from sensors back to a sink, but in an ad hoc network this may be of secondary importance. Hence, protocols suitable to sensor networks are not necessarily suitable to ad hoc networks and vice versa. We propose, Resource Aware Information Collection (RAIC), a distributed two phased resource aware approach to information collection in ad hoc networks. RAIC utilises a resource aware optimised flooding mechanism to both disseminate requests and initialise a backbone of resource suitable nodes responsible for relaying replies back to the node collecting information. RAIC in the process of collecting information from all nodes in an ad hoc network is shown to consume less energy and introduce less overhead compared with Directed Diffusion and a brute force approach. Importantly, over multiple successive queries (in an energy constrained environment), the use of resource awareness allows for the load of relaying to be distributed to those nodes most suitable, thereby extending the lifetime of the network.     

A heterogeneous‐network aided public‐key management scheme for mobile ad hoc networks

A mobile ad hoc network does not require fixed infrastructure to construct connections among nodes. Due to the particular characteristics of mobile ad hoc networks, most existing secure protocols in wired networks do not meet the security requirements for mobile ad hoc networks. Most secure protocols in mobile ad hoc networks, such as secure routing, key agreement and secure group communication protocols, assume that all nodes must have pre‐shared a secret, or pre‐obtained public‐key certificates before joining the network. However, this assumption has a practical weakness for some emergency applications, because some nodes without pre‐obtained certificates will be unable to join the network. In this paper, a heterogeneous‐network aided public‐key management scheme for mobile ad hoc networks is proposed to remedy this weakness. Several heterogeneous networks (such as satellite, unmanned aerial vehicle, or cellular networks) provide wider service areas and ubiquitous connectivity. We adopt these wide‐covered heterogeneous networks to design a secure certificate distribution scheme that allows a mobile node without a pre‐obtained certificate to instantly get a certificate using the communication channel constructed by these wide‐covered heterogeneous networks. Therefore, this scheme enhances the security infrastructure of public key management for mobile ad hoc networks. Copyright © 2006 John Wiley & Sons, Ltd.     

Enhanced fuzzy logic‐based spray and wait routing protocol for delay tolerant networks

Delay tolerant networks are a class of ad hoc networks that enable data delivery even in the absence of end‐to‐end connectivity between nodes, which is the basic assumption for routing in ad hoc networks. Nodes in these networks work on store‐carry and forward paradigm. In addition, such networks make use of message replication as a strategy to increase the possibility of messages reaching their destination. As contact opportunities are usually of short duration, it is important to prioritize scheduling of messages. Message replication may also lead to buffer congestion. Hence, buffer management is an important issue that greatly affects the performance of routing protocols in delay tolerant networks. In this paper, Spray and Wait routing protocol, which is a popular controlled replication‐based protocol for delay tolerant networks, has been enhanced using a new fuzzy‐based buffer management strategy Enhanced Fuzzy Spray and Wait Routing, with the aim to achieve increased delivery ratio and reduced overhead ratio. It aggregates three important message properties namely number of replicas of a message, its size, and remaining time‐to‐live, using fuzzy logic to determine the message priority, which denotes its importance with respect to other messages stored in a node's buffer. It then intelligently selects messages to schedule when a contact opportunity occurs. Because determination of number of replicas of a message in the network is a difficult task, a new method for estimation of the same has been proposed. Simulation results show improved performance of enhanced fuzzy spray and wait routing in terms of delivery ratio and resource consumption. Copyright © 2014 John Wiley & Sons, Ltd.     

An efficient load balancing method for ad hoc networks

Routing is the most basic and essential operation of any ad hoc network. A mobile ad hoc network presents many challenges, because of the severe resource limitations such as dynamic and varying topology, lack of centralized control, insecure medium, and limited battery power, among others. Therefore, optimization and conservation is the key to success of any ad hoc network operation. In this paper, we propose and define 2 new metrics for ad hoc networks: bandwidth utilization ratio and load index. These metrics can be used as an indicator to measure and monitor the network usability and to improve its efficiency by efficient load distribution. They can be used to predict the additional load that can be accommodated in the network, without causing any congestion or overflows. We also propose a new load balancing routing scheme for ad hoc networks, called efficient load balancing method. This method tries to offset the load on different paths using load index as a metric. Load index is defined as a measure of a node's degree of involvement in the message routing process, which is indicative of its load. To make this algorithm efficient, we limit our routes to a few efficient ones only. This number of alternate routes used, out of the pool of all available routes, is defined as degree of distribution. Simulation results adequately prove the efficiency of proposed method, vis‐à‐vis 2 other load balancing approaches, and these are verified statistically at 99% confidence interval. A p × q factorial design is used to verify that simulation results are the actual measurements and not due to some unknown errors.     

Improving handoff performance by utilizing ad hoc links in multi-hop cellular systems

Handoff performance is a critical issue for mobile users in wireless cellular networks, such as GSM networks, 3G networks, and next generation networks (NGNs). When ad hoc mode is introduced to cellular networks, multi-hop handoffs become inevitable, which brings in new challenging issues to network designers, such as how to reduce the call dropping rate, how to simplify the multi-hop handoff processes, and how to take more advantage of ad hoc mode for better resource management, and most of these issues have not been well addressed as yet. In this paper, we will address some of the issues and propose a scheme, Ad-hoc-Network–Embedded handoff Assisting Scheme (ANHOA), which utilizes the self-organizing feature of ad hoc networks to facilitate handoffs in cellular networks and provide an auxiliary way for mobile users to handoff across different cells. Moreover, we also propose a scheme enabling each BS to find the feasible minimum reservation for handoff calls based on the knowledge of adjacent cells’ traffic information. Due to the use of multi-hop connections, our scheme can apparently alleviate the reservation requirement and lower the call blocking rate while retaining higher spectrum efficiency. We further provide a framework for information exchange among adjacent cells, which can dynamically balance the load among cells. Through this study, we demonstrate how we can utilize ad hoc mode in cellular systems to significantly improve the handoff performance.     

The diameter of mobile ad hoc networks

With the prevalence of mobile devices, it is of much interest to study the properties of mobile ad hoc networks. In this paper, we extend the concept of diameter from static ad hoc network to mobile ad hoc network, which is the expected number of rounds for one node to transmit a message to all other nodes in the network, reflecting the worst end‐to‐end delay between any two node. Specifically, we investigate the diameter of identically and independently mobility model in cell‐partitioned network and random walk mobility model in two‐dimensional torus network, achieving the boundary , when (k=Ω(n)), and O(k log2k), respectively, where n is the number of nodes and k is the number of cells of network and especially under random walk mobility model . A comparison is made among the diameter of mobile ad hoc networks under identically and independently mobility model, random walk mobility model and static ad hoc network, showing that mobility dramatically decreases the diameter of the network and speed is an essential and decisive factor of diameter. Copyright © 2016 John Wiley & Sons, Ltd.     

LHAP: A lightweight network access control protocol for ad hoc networks

Most ad hoc networks do not implement any network access control, leaving these networks vulnerable to resource consumption attacks where a malicious node injects packets into the network with the goal of depleting the resources of the nodes relaying the packets. To thwart or prevent such attacks, it is necessary to employ authentication mechanisms to ensure that only authorized nodes can inject traffic into the network. We propose LHAP, a hop-by-hop authentication protocol for ad hoc networks. LHAP resides in between the network layer and the data link layer, thus providing a layer of protection that can prevent or thwart many attacks from happening, including outsider attacks and insider impersonation attacks. Our detailed performance evaluation shows that LHAP incurs small performance overhead and it also allows a tradeoff between security and performance.     

Optimal resource allocation in wireless ad hoc networks: a price-based approach

The shared-medium multihop nature of wireless ad hoc networks poses fundamental challenges to the design of effective resource allocation algorithms that are optimal with respect to resource utilization and fair across different network flows. None of the existing resource allocation algorithms in wireless ad hoc networks have realistically considered end-to-end flows spanning multiple hops. Moreover, strategies proposed in wireline networks are not applicable in the context of wireless ad hoc networks, due to their unique characteristics of location-dependent contention. In this paper, we propose a new price-based resource allocation framework in wireless ad hoc networks to achieve optimal resource utilization and fairness among competing end-to-end flows. We build our pricing framework on the notion of maximal cliques in wireless ad hoc networks, as compared to individual links in traditional wide-area wireline networks. Based on such a price-based theoretical framework, we present a two-tier iterative algorithm. Distributed across wireless nodes, the algorithm converges to a global network optimum with respect to resource allocations. We further improve the algorithm toward asynchronous network settings and prove its convergence. Extensive simulations under a variety of network environments have been conducted to validate our theoretical claims.     

A mobicast routing protocol with carry‐and‐forward in vehicular ad hoc networks

In vehicular networks, safety and comfort applications are two quite different kinds of applications to avoid the emergency traffic accident and enjoy the non‐emergency entertainment. The comfort application drives the challenges of new non‐emergency entertainments for vehicular ad hoc networks (VANETs). The comfort application usually keeps the delay‐tolerant capability; that is, messages initiated from a specific vehicle at time t can be delivered through VANETs to some vehicles within a given constrained delay time λ. In this paper, we investigate a new mobicast protocol to support comfort applications for a highway scenario in VANETs. All vehicles are located in a geographic zone (denoted as zone of relevance (ZOR)) at time t; the mobicast routing must disseminate the data message initiated from a specific vehicle to all vehicles that have ever appeared in ZOR at time t. This data dissemination must be performed before time t + λ through the carry‐and‐forward technique. In addition, the temporary network fragmentation problem is considered in our protocol design. Also, the low degree of channel utilization is kept to reserve the resource for safety applications. To illustrate the performance achievement, simulation results are examined in terms of message overhead, dissemination success rate, and accumulative packet delivery delay. Copyright © 2012 John Wiley & Sons, Ltd.     

Quality of service challenges for wireless mobile ad hoc networks

Wireless mobile ad hoc networks consist of mobile nodes interconnected by wireless multi‐hop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. The topology of such networks changes dynamically as mobile nodes join or depart the network or radio links between nodes become unusable. Supporting appropriate quality of service for mobile ad hoc networks is a complex and difficult issue because of the dynamic nature of the network topology and generally imprecise network state information, and has become an intensely active area of research in the last few years. This paper

1 This article, except for some minor changes, is essentially the same as one that appears in 103 . The latter is a revised and updated version of 51

presents the basic concepts of quality of service support in ad hoc networks for unicast communication, reviews the major areas of current research and results, and addresses some new issues. The principal focus is on routing and security issues associated with quality of service support. The paper concludes with some observations on the open areas for further investigation. Copyright © 2004 John Wiley & Sons, Ltd.     

SMORT: Scalable multipath on-demand routing for mobile ad hoc networks

Increasing popularity and availability of portable wireless devices, which constitute mobile ad hoc networks, calls for scalable ad hoc routing protocols. On-demand routing protocols adapt well with dynamic topologies of ad hoc networks, because of their lower control overhead and quick response to route breaks. But, as the size of the network increases, these protocols cease to perform due to large routing overhead generated while repairing route breaks. We propose a multipath on-demand routing protocol (SMORT), which reduces the routing overhead incurred in recovering from route breaks, by using secondary paths. SMORT computes fail-safe multiple paths, which provide all the intermediate nodes on the primary path with multiple routes (if exists) to destination. Exhaustive simulations using GloMoSim with large networks (2000 nodes) confirm that SMORT is scalable, and performs better even at higher mobility and traffic loads, when compared to the disjoint multipath routing protocol (DMRP) and ad hoc on-demand distance vector (AODV) routing protocol.     

Designing a wireless network with directional antennas: frequency division issue

We design a mobile ad‐hoc network (MANET), where nodes are equipped with several multi‐beam adaptive array (MBAA) systems. Such devices provide a great advantage for both space and frequency freedom, and produce a much better network throughput than traditional systems based on single frequency, omnidirectional transmission. A license‐free bandwidth up to 7 GHz is available centered at 60 GHz. The problem to divide this bandwidth into several channels is described as frequency division issue in this paper. We have provided a possible solution for such a problem in our paper, formulated as a (K, M) list‐coloring problem of the associated graph. Major results are presented based on two different models for connection requests. In addition, a numerical test is performed to verify the analysis. Copyright © 2004 John Wiley & Sons, Ltd.     

Self‐adaptive routing protocols for integrating cellular networks,WLANs, and MANETs

A growing need to have ubiquitous connectivity has motivated our research to provide continuous connection between various wireless platforms such as cellular networks, wireless local area networks (WLANs), and mobile ad hoc networks (MANETs). In this paper, we consider integration at the routing layer and propose two adaptable routing protocols (IRP‐RD and IRP‐PD) that exploit topology information stored at the fixed network components (cellular base stations and WLAN access points) for the route discovery and maintenance processes. Our proposed protocols can provide connectivity to the cellular network and/or WLAN hotspots through multihop routing, while differ in the gateway discovery approach used. In IRP‐RD, multihop routes to gateways to the cellular network or WLAN hot spots are discovered on demand, while in IRP‐PD out of coverage users proactively maintain routes to the gateways. Furthermore, proposed protocols can be used in any heterogeneous scenario, combining a cellular network and WLANs operating in infrastructure or ad hoc (MANET) mode. We provide simulation results that demonstrate the effectiveness of the proposed integrated routing protocols and show the advantages and drawbacks of each gateway discovery approach in different heterogeneous scenarios. Copyright © 2006 John Wiley & Sons, Ltd.     

A proactive management algorithm for self‐healing mobile ad hoc networks

The ability to proactively manage mobile ad hoc networks (MANETs) is critical for supporting complex services such as quality of service, security and access control in these networks. This paper focuses on the problem of managing highly dynamic and resource‐constrained MANET environments through the proposal of a novel proactive management algorithm (PMA) for self‐healing MANETs. PMA is based on an effective integration of autonomous, predictive and adaptive distributed management strategies. Proactive management is achieved through the distributed analysis of the current performance of the mobile nodes utilizing an optimistic discrete event simulation method, which is used to predict the mobile nodes' future status, and execution a proactive fault‐tolerant management scheme. PMA takes advantage of distributed parallel processing, flexibility and intelligence of active packets to minimize the management overhead, while adapting to the highly dynamic and resource‐constrained nature of MANETs. The performance of the proposed architecture is validated through analytical performance analysis and comparative simulation with the Active Virtual Network Management Protocol. The simulation results demonstrate that PMA not only significantly reduces management control overhead, but also improves both the performance and the stability of MANETs. Copyright © 2007 John Wiley & Sons, Ltd.     

TIDS: threshold and identity-based security scheme for wireless ad hoc networks

As various applications of wireless ad hoc network have been proposed, security has received increasing attentions as one of the critical research challenges. In this paper, we consider the security issues at network layer, wherein routing and packet forwarding are the main operations. We propose a novel efficient security scheme in order to provide various security characteristics, such as authentication, confidentiality, integrity and non-repudiation for wireless ad hoc networks. In our scheme, we deploy the recently developed concepts of identity-based signcryption and threshold secret sharing. We describe our proposed security solution in context of dynamic source routing (DSR) protocol. Without any assumption of pre-fixed trust relationship between nodes, the ad hoc network works in a self-organizing way to provide key generation and key management services using threshold secret sharing algorithm, which effectively solves the problem of single point of failure in the traditional public-key infrastructure (PKI) supported system. The identity-based signcryption mechanism is applied here not only to provide end-to-end authenticity and confidentiality in a single step, but also to save network bandwidth and computational power of wireless nodes. Moreover, one-way hash chain is used to protect hop-by-hop transmission.     

Safari: A self-organizing, hierarchical architecture for scalable ad hoc networking

As wireless devices become more pervasive, mobile ad hoc networks are gaining importance, motivating the development of highly scalable ad hoc networking techniques. In this paper, we give an overview of the Safari architecture for highly scalable ad hoc network routing, and we present the design and evaluation of a specific realization of the Safari architecture, which we call Masai. We focus in this work on the scalability of learning and maintaining the routing state necessary for a large ad hoc network. The Safari architecture provides scalable ad hoc network routing, the seamless integration of infrastructure networks when and where they are available, and the support of self-organizing, decentralized network applications. Safari’s architecture is based on (1) a self-organizing network hierarchy that recursively groups participating nodes into an adaptive, locality-based hierarchy of cells; (2) a routing protocol that uses a hybrid of proactive and reactive routing information in the cells and scales to much larger numbers of nodes than previous ad hoc network routing protocols; and (3) a distributed hash table grounded in the network hierarchy, which supports decentralized network services on top of Safari. We evaluate the Masai realization of the Safari architecture through analysis and simulations, under varying network sizes, fraction of mobile nodes, and offered traffic loads. Compared to both the DSR and the L+ routing protocols, our results show that the Masai realization of the Safari architecture is significantly more scalable, with much higher packet delivery ratio and lower overhead.     

ECDGP: extended cluster‐based data gathering protocol for vehicular networks

An important application in wireless networks is data collection. It aims to gather and deliver specific data for concerned authorities. Many researchers invest in vehicular ad hoc networks for that purpose to acquire data from different sources on the roads as from its vicinity. A vehicle is considered as a mobile data collector, it gathers real‐time or delay‐tolerant data such as road traffic, environmental information, and event advertisements. In a previous work, we have proposed a novel clustered data gathering protocol (CDGP) for vehicular ad hoc network, which improves the collection performance by implementing a new space division multiple access technique called dynamic space division multiple access and a retransmission mechanism in case of errors. However, CDGP supports only delay‐tolerant data as it does not use any aggregation technique. In this paper, we propose an enhancement of this protocol by extending it to support: (i) both real‐time and delay‐tolerant applications; (ii) multiple types of data; and (iii) aggregation of collected data prior to sending them to the initiator. We present the plausible analytical complexity of the extended CDGP, as we illustrate the superiority of its performance throughout the results obtained from simulation experiments, using a Freeway mobility model. Copyright © 2015 John Wiley & Sons, Ltd.     

HSG‐ad hoc network: A novel hierarchical star graph ad hoc network with self‐organization and routing discovery free

In ad hoc wireless networks, most data are delivered by multi‐hop routing (hop by hop). This approach may cause long delay and a high routing overhead regardless of which routing protocol is used. To mitigate this inherent characteristic, this work presents a novel ad hoc network structure that adopts dual‐card‐mode, self‐organization with specific IP naming and channel assignment to form a hierarchical star graph ad hoc network (HSG‐ad hoc). This network not only expedites data transmission but also eliminates the route discovery procedure during data transmission. Therefore, the overall network reliability and stability are significantly improved. Simulation results show that the proposed approach achieves substantial improvements over DSDV, AODV, and DSR in terms of average end‐to‐end delay, throughput, and packet delivery ratio. Copyright © 2009 John Wiley & Sons, Ltd.     

On the capacity of mobile ad hoc networks with delay constraints

Previous work on ad hoc network capacity has focused primarily on source-destination throughput requirements for different models and transmission scenarios, with an emphasis on delay tolerant applications. In such problems, network capacity enhancement is achieved as a tradeoff with transmission delay. In this paper, the capacity of ad hoc networks supporting delay sensitive traffic is studied. First, a general framework is . proposed for characterizing the interactions between the physical and the network layer in an ad hoc network. Then, CDMA ad hoc networks, in which advanced signal processing techniques such as multiuser detection are relied upon to enhance the user capacity, are analyzed. The network capacity is characterized using a combination of geometric arguments and large scale analysis, for several network scenarios employing matched filters, decorrelators and minimum-mean-square-error receivers. Insight into the network performance for finite systems is also provided by means of simulations. Both analysis and simulations show a significant network capacity gain for ad hoc networks employing multiuser detectors, compared with those using matched filter receivers, as well as very good performance even under tight delay and transmission power requirements.