Conventional Wireless Networks Research Articles

Secured and Optimized AODV for Wireless Sensor Networks

Similar to conventional wireless networks, WSNs are based on multi hop routing to ensure connectivity and data forwarding which makes the routing service a challenging task due to the nature of sensors usually limited in memory, battery and computing capacities as well as the nature of the environment which is hostile and unpredictable making the routing protocols developed for conventional wireless network useless for WSNs without modifications and adaptations for the new context of WSNs. Thus in this paper we present an optimized version of AODV protocol for WSNs which takes into consideration the traffic pattern of WSNs and sensors' constraints. In the proposed protocol we affect the task of route discovery to the base station which periodically informs sensors about its location instead of letting this task to sensors which consumes the network resources due to the broadcasting nature of the route discovery. We have also proposed a key distribution scheme destined to establish a symmetric encrypting key between each sensor and the base station, the proposed key management scheme uses the underlying routing requests to execute handshakes and key update which have greatly saved the network resources and ensured a good threshold of security.

Conjoint trust assessment for secure communication in cognitive radio networks

With the rapid development of wireless communication, the growth of Cognitive Radio (CR) is increasing day by day. Because CR is flexible and operates on the wireless network, there are more security threats to CR technology than to the traditional radio environment. In addition, there is no comprehensive framework for achieving security in Cognitive Radio Networks (CRNs), and the role of trust for achieving security in CRNs has not been explored previously. Security vulnerability in cognitive radio technology is unavoidable due to the intrinsic nature of the technology, so it is critical to ensure system security in CRNs. The issue of secure communication in CRNs thus becomes more important than it is in conventional wireless networks. In this paper, we propose a conjoint trust assessment approach (combining trust assessment from the Primary User Network and the Secondary User Network) in a CRN to solve the security threats brought about by untrustworthy entities, such as selfish, malicious, and faultless nodes, and to ensure secure spectrum sharing in CRNs. A numerical analysis shows the feasibility of our proposed approach.

Fault Diagnosis in Wireless Sensor Networks: A Survey

The sensor nodes in wireless sensor networks may be deployed in unattended and possibly hostile environments. The ill-disposed environment affects the monitoring infrastructure that includes the sensor nodes and the network. In addition, node failures and environmental hazards cause frequent topology changes, communication failures, and network partitioning. This in turn adds a new dimension to the fragility of the network topology. Such perturbations are far more common than those found in conventional wireless networks thus, demand efficient techniques for discovering disruptive behavior in such networks. Traditional fault diagnosis techniques devised for multiprocessor systems are not directly applicable to wireless sensor networks due to their specific requirements and limitations. This survey integrates research efforts that have been produced in fault diagnosis specifically for wireless sensor networks. The survey aims at clarifying and uncovering the potential of this technology by providing the technique-based taxonomy. The fault diagnosis techniques are classified based on the nature of the tests, correlation between sensor readings and characteristics of sensor nodes and the network.

A Survey on Security Threats and Detection Techniques in Cognitive Radio Networks

With the rapid proliferation of new technologies and services in the wireless domain, spectrum scarcity has become a major concern. The allocation of the Industrial, Medical and Scientific (ISM) band has enabled the explosion of new technologies (e.g. Wi-Fi) due to its licence-exempt characteristic. The widespread adoption of Wi-Fi technology, combined with the rapid penetration of smart phones running popular user services (e.g. social online networks) has overcrowded substantially the ISM band. On the other hand, according to a number of recent reports, several parts of the static allocated licensed bands are under-utilized. This has brought up the idea of the opportunistic use of these bands through the, so-called, cognitive radios and cognitive radio networks. Cognitive radios have enabled the opportunity to transmit in several licensed bands without causing harmful interference to licensed users. Along with the realization of cognitive radios, new security threats have been raised. Adversaries can exploit several vulnerabilities of this new technology and cause severe performance degradation. Security threats are mainly related to two fundamental characteristics of cognitive radios: cognitive capability, and reconfigurability. Threats related to the cognitive capability include attacks launched by adversaries that mimic primary transmitters, and transmission of false observations related to spectrum sensing. Reconfiguration can be exploited by attackers through the use of malicious code installed in cognitive radios. Furthermore, as cognitive radio networks are wireless in nature, they face all classic threats present in the conventional wireless networks. The scope of this work is to give an overview of the security threats and challenges that cognitive radios and cognitive radio networks face, along with the current state-of-the-art to detect the corresponding attacks. In addition, future challenges are addressed.

Capacity of Hybrid Wireless Mesh Networks with Random APs

In conventional Wireless Mesh Networks (WMNs), multihop relays are performed in the backbone comprising of interconnected Mesh Routers (MRs) and this causes capacity degradation. This paper proposes a hybrid WMN architecture that the backbone is able to utilize random connections to Access Points (APs) of Wireless Local Area Network (WLAN). In such a proposed hierarchal architecture, capacity enhancement can be achieved by letting the traffic take advantage of the wired connections through APs. Theoretical analysis has been conducted for the asymptotic capacity of three-tier hybrid WMN, where per-MR capacity in the backbone is first derived and per-MC capacity is then obtained. Besides related to the number of MR cells as a conventional WMN, the analytical results reveal that the asymptotic capacity of a hybrid WMN is also strongly affected by the number of cells having AP connections, the ratio of access link bandwidth to backbone link bandwidth, etc. Appropriate configuration of the network can drastically improve the network capacity in our proposed network architecture. It also shows that the traffic balance among the MRs with AP access is very important to have a tighter asymptotic capacity bound. The results and conclusions justify the perspective of having such a hybrid WMN utilizing widely deployed WLANs.

A directional MAC for switchable directional antennas to enhance throughput in crowded infrastructure wireless networks

In conventional infrastructure wireless networks, access points and nodes use omni-directional antennas. In a crowded situation, users have experienced throughput degradation due to various reasons. In this paper, we propose wireless LANs equipped with switchable directional antennas and a directional MAC protocol designed for them. In the proposed wireless LAN, every node including access point is always engaged in directional transmission and reception, but a node is allowed to receive omni-directionally only for association process. This new system enhances throughput in overlapped multiple basic service sets by reducing interference, increasing spatial reuse, and avoiding transmission loss phenomenon TLP. The simulation results show that the proposed protocol outperforms conventional IEEE 802.11 DCF, in terms of throughput in crowded infrastructure wireless networks.

On the Use of Smart Ants for Efficient Routing in Wireless Mesh Networks

Routing in wireless mesh networks (WMNs) has been an active area of research for the last several years. In this paper, we address the problem of packet routing for efficient data forwarding in wireless mesh networks (WMNs) with the help of smart ants acting as intelligent agents. The aim of this paper is to study the use of such biologically inspired agents to effectively route the packets in WMNs. In particular, we propose AntMesh, a distributed interference-aware data forwarding algorithm which enables the use of smart ants to probabilistically and concurrently perform the routing and data forwarding in order to stochastically solve a dynamic network routing problem. AntMesh belongs to the class of routing algorithms inspired by the behaviour of real ants which are known to find a shortest path between their nest and a food source. In addition, AntMesh has the capability to effectively utilize the space/channel diversity typically common in multi radio WMNs and to discover high throughput paths with less interflow and intra-flow interference while conventional wireless network routing protocols fail to do so. We implement our smart ant-based routing algorithm in ns-2 and carry out extensive evaluation. We demonstrate the stability of AntMesh in terms of how quickly it adapts itself to the changing dynamics or load on the network. We tune the parameters of AntMesh algorithm to study the effect on its performance in terms of the routing load and end-to-end delay and have tested its performance under various network scenarios particularly fixed nodes mesh networks and also on mobile WMN scenarios. The results obtained show AntMesh's advantages that make it a valuable candidate to operate in mesh networks.

Wireless Network Coding Diversity Technique Based on Hybrid AF/DF Relay Method Employing Adaptive Power Control at Relay Node for Bidirectional Two-Hop Wireless Networks

In this paper, we propose a wireless network coding diversity technique based on hybrid amplify-and-forward/decode-and-forward relay method employing adaptive power control for two-hop wireless networks in order to improve relay node position flexibility. Wireless network coding diversity based on hybrid relay method selects either modulation symbol level wireless network coding diversity or bit sequence level wireless network coding diversity as its wireless network coding diversity scheme according to the cyclic redundancy check result at the relay node. Moreover, the adaptive power control scheme proposed here controls the relay node's transmit power according to its position. Computer simulations verify that wireless network coding diversity based on hybrid relay method employing the adaptive power control scheme can expand the area wherein the relay node can be located while satisfying the required communication quality by 4.56 times compared to the conventional wireless network coding diversity scheme. Therefore, we confirm that our proposed scheme can increase relay node position flexibility.

Physical Layer Cryptography and Cognitive Networks

Recently the huge development of different and heterogeneous wireless communication systems raises the problem of growing spectrum scarcity. Cognitive radio tends to solve this problem by dynamically utilizing the spectrum. Security in cognitive radio network becomes a challenging issue, since more chances are given to attackers by cognitive radio technology compared to conventional wireless network. These weaknesses are introduced by the nature itself of cognitive radio, and they may cause serious impact to the network quality of service. However, to the authors' knowledge, there are no specific secure protocols for cognitive radio networks. This paper will discuss the vulnerabilities inherent to cognitive radio systems, identify novel types of abuse, classify attacks, and analyze their impact. Security solutions to mitigate such threats will be proposed and discussed. In particular, physical payer security will be taken into account. A new modulation technique, able to encrypt the radio signal without any a priori common secret between the two nodes, was previously proposed by the authors (Mucchi et al. 2009, WPC 51, 67---80; Mucchi et al. 2010, WPC 53, 329---347). The information is modulated, at physical layer, by the thermal noise experienced by the link between two terminals. A loop scheme is designed for unique recovering of mutual information. This contribution improves the previous works by proposing the noise loop modulation as physical layer security technique for cognitive radio networks.

Advances in standards and testbeds for cognitive radio networks: part I [Guest Editorial

Conventional wireless networks have been designed from a centralized perspective and with a predefined infrastructure, such as cellular networks, but this rigid approach lacks flexibility and adaptability, which are advantages of nextgeneration cognitive radio systems. Thus, it is of paramount importance to design self-configurable cognitive-radio-based networks that are aware of and adaptable to the changing environment to coexist harmoniously with other wireless systems that use a variety of protocols in the same frequency bands. The design of such networks requires the development of a number of new access and transmission technologies to ensure successful coexistence and to avoid causing harmful interference. Cognitive radio technologies such as dynamic spectrum access create huge opportunities for interesting research and development in a wide range of applications including spectrum sensing, navigation, and biomedical/ health.

A New Group Key Agreement Protocol for Ad Hoc Networks

A mobile ad hoc network is a collection of autonomous nodes that communicate with each other by forming a multi-top wireless network. Different from conventional wireless networks, the resource of the nodes in ad hoc networks is limited and there may be tens of thousands of low-power energy constrained nodes in ad hoc networks. As such, the costs of the nodes resource and the network size should be taken into consideration when constructing a group key agreement protocol in the ad hoc networks. In this paper, an efficient and scalable group key agreement protocol based on layer-cluster group model for mobile ad hoc networks was proposed. In this protocol, multi-linear map is employed on layer-cluster structure to establish and allocate group key. So that it can not only meet security demands of larger mobile ad hoc networks but also improve executing performance.

DCAR: Distributed Coding-Aware Routing in Wireless Networks

Recently, there has been a growing interest of using network coding to improve the performance of wireless networks, for example, authors of proposed the practical wireless network coding system called COPE, which demonstrated the throughput gain achieved by network coding. However, COPE has two fundamental limitations: (1) the coding opportunity is crucially dependent on the established routes and (2) the coding structure in COPE is limited within a two-hop region only. The aim of this paper is to overcome these limitations. In particular, we propose DCAR, the distributed coding-aware routing mechanism which enables: (1) the discovery for available paths between a given source and destination and (2) the detection for potential network coding opportunities over much wider network region. One interesting result is that DCAR has the capability to discover high throughput paths with coding opportunities, while conventional wireless network routing protocols fail to do so. In addition, DCAR can detect coding opportunities on the entire path, thus eliminating the ?two-hop? coding limitation in COPE. We also propose a novel routing metric called coding-aware routing metric (CRM) which facilitates the performance comparison between ?coding-possible? and coding-impossible? paths. We implement the DCAR system in ns-2 and carry out extensive evaluation. We show that when comparing to the coding mechanism in, DCAR can achieve much higher throughput gain.

Constructing secured cognitive wireless networks: experiences and challenges

AbstractRecent development in wireless communications has lead to the problem of growing spectrum shortage. Cognitive radio, as a novel technology, has been proposed in recent years to solve this problem by dynamically accessing the spectrum so as to enhance the spectrum utilization. Security in cognitive radio networks has become a challenging issue because there are more chances open to attackers by cognitive radio technology, compared to those from conventional wireless networks. These weaknesses and vulnerable aspects, introduced by the nature of cognitive radio, may cause serious impact on the security and quality of service (QoS) provisioning for the entire network. Unfortunately, at present, there is no specific secure protocol designed for cognitive radio networks. Therefore, in this paper, we conduct a high‐level survey to review and reflect the state‐of‐the‐art work on the security issues in cognitive networks. We focus on analyzing the security system at the macroscopic level, where both protection and detection are considered to be the most essential parts to ensure security in the whole network. Furthermore, we investigate special characteristics of cognitive networks at different protocol layers, including physical layer, link layer, network layer, transport layer and application layer. We recognize both the challenges and experiences, and focus on constructing the secured cognitive wireless networks. Copyright © 2009 John Wiley & Sons, Ltd.

Video transmission enhancement in presence of misbehaving nodes in MANETs

Mobile Ad-hoc NETworks (MANET) are infrastructureless networks where self-configuring mobile nodes are connected by wireless links. Because of its decentralized operation, these nodes rely on each other to store and forward packets. Video transmission over MANETs is more challenging than over conventional wireless networks due to rapid topology changes and lack of central administration. Most of the proposed MANET protocols assume that all nodes are working within a cooperative and friendly network context. However, misbehaving nodes that exhibit abnormal behaviors can disrupt the network operation and affect the network availability by refusing to cooperate to route packets due to their selfish or malicious behavior. In this paper, we examine the effect of packet dropping attacks on video transmission over MANETs. We also study the effects of mitigation using intrusion detection systems to MANET in presence of video traffic. To the best of our knowledge, this is the first attempt to study multimedia over such environments. We propose a novel intrusion detection system, which is an adaptive acknowledgment scheme (AACK) with the ability to detect misbehaved nodes and avoid them in other transmissions. The aim of AACK scheme is to overcome watchdog weaknesses due to collisions and limited transmission power and also to improve TWOACK scheme. To demonstrate the performance of our proposed scheme, simulation experiments are performed. The results of our experiments show that MPEG4 is more suitable for our simulation environment than H264 video traffic. The simulation results show that AACK scheme provides better network performance with less overhead than other schemes; it also shows that AACK outperforms both TWOACK and watchdog in video transmission applications in the presence of misbehaving nodes.

Preserving data integrity in mobile ad hoc networks with variant Diffie‐Hellman protocol

AbstractSince the early 1990s, engineers have proposed many mechanisms for providing confidential communications and data integrity in mobile ad hoc networks (MANET). The deficiency of fastened infrastructure makes mobile ad hoc networks more vulnerable to security threats than conventional wireless networks. MANET can be considered as a short‐lived collection of mobile nodes that communicate with each other in between. All involved nodes in the network system share the responsibility for routing, accessing, and communicating. The main challenges on the design of MANET include high power saving and low bandwidth. The public key infrastructure (PKI) is a well‐known mechanism used to provide data integrity and confidential communications in MANET recently. The computation loads of PKI, however, are heavy to each mobile node in the cluster. Without adopting PKI cryptosystems to en/decrypt messages, we propose a novel version based on a variant Diffie‐‐Hellman protocol. The novel method can preserve the forward and backward secrecy of group communications. Specifically, the new method outperforms related works in the computation overheads of involved nodes while communicating with other nodes. Copyright © 2008 John Wiley & Sons, Ltd.

QoS-aware multicast routing protocol for Ad hoc networks

Ad hoc wireless networks consist of mobile nodes interconnected by multihop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. Due to bandwidth constraint and dynamic topology of mobile ad hoc networks, supporting Quality of Service (QoS) is an inherently complex, difficult issue and very important research issue. MAODV (Multicast Ad hoc On-demand Distance Vector) routing protocol provides fast and efficient route establishment between mobile nodes that need to communicate with each other. MAODV has minimal control overhead and route acquisition latency. In addition to unicast routing, MAODV supports multicast and broadcast as well. The multicast routing problem with multiple QoS constraints, which may deal with the delay, bandwidth and packet loss measurements is discussed, and a network model for researching the ad hoc network QoS multicast routing problem is described. It presents a complete solution for QoS multicast routing based on an extension of the MAODV routing protocol that deals with delay, bandwidth and packet loss measurements. The solution is based on lower layer specifics. Simulation results show that, with the proposed QoS multicast routing protocol, end-to-end delay, bandwidth and packet loss on a route can be improved in most of cases. It is an available approach to multicast routing decision with multiple QoS constraints.

Efficient identity-based security schemes for ad hoc network routing protocols

Wireless ad hoc networks consist of nodes with no central administration and rely on the participating nodes to share network responsibilities. Such networks are more vulnerable to security attacks than conventional wireless networks. We propose two efficient security schemes for these networks that use pairwise symmetric keys computed non-interactively by the nodes which reduces communication overhead. We allow nodes to generate their broadcast keys for different groups and propose a collision-free method for computing such keys. We use identity-based keys that do not require certificates which simplifies key management. Our key escrow free scheme also uses identity-based keys but eliminates inherent key escrow in identity-based keys. Our system requires a minimum number of keys to be generated by the third party as compared to conventional pairwise schemes. We also propose an authenticated broadcast scheme based on symmetric keys and a corresponding signature scheme.

Topology and mobility considerations in mobile ad hoc networks

A highly dynamic topology is a distinguishing feature and challenge of a mobile ad hoc network. Links between nodes are created and broken, as the nodes move within the network. This node mobility affects not only the source and/or destination, as in a conventional wireless network, but also intermediate nodes, due to the network’s multihop nature. The resulting routes can be extremely volatile, making successful ad hoc routing dependent on efficiently reacting to these topology changes. In order to better understand this environment, a number of characteristics have been studied concerning the links and routes that make up an ad hoc network. Several network parameters are examined, including number of nodes, network dimensions, and radio transmission range, as well as mobility parameters for maximum speed and wait times. In addition to suggesting guidelines for the evaluation of ad hoc networks, the results reveal several properties that should be considered in the design and optimization of MANET protocols.

Quality of service challenges for wireless mobile ad hoc networks

AbstractWireless 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 paperThis 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.

On Increasing Service Accessibility and Efficiency in Wireless Ad-Hoc Networks with Group Mobility

Wireless ad-hoc networks consist of mobile nodes interconnected by multi-hop wireless paths. Unlike conventional wireless networks, ad-hoc networks have no fixed network infrastructure or administrative support. Because of the dynamic nature of the network topology and limited bandwidth of wireless channels, Quality-of-Service (QoS) provisioning is an inherently complex and difficult issue. In this paper, we propose a fully distributed and adaptive algorithm to provide statistical QoS guarantees with respect to accessibility of services in an ad-hoc network. In this algorithm, we focus on the optimization of a new QoS parameter of interest, service efficiency, while keeping protocol overheads to the minimum. To achieve this goal, we theoretically derive the lower and upper bounds of service efficiency based on a novel model for group mobility, followed by extensive simulation results to verify the effectiveness of our algorithm.