Routing security in wireless ad hoc networks

A mobile ad hoc network consists of a collection of wireless mobile nodes that are capable of communicating with each other without the use of a network infrastructure or any centralized administration. MANET is an emerging research area with practical applications. However, wireless MANET is particularly vulnerable due to its fundamental characteristics, such as open medium, dynamic topology, distributed cooperation, and constrained capability. Routing plays an important role in the security of the entire network. In general, routing security in wireless MANETs appears to be a problem that is not trivial to solve. In this article we study the routing security issues of MANETs, and analyze in detail one type of attack-the "black hole" problem-that can easily be employed against the MANETs. We also propose a solution for the black hole problem for ad hoc on-demand distance vector routing protocol.     

A localized certificate revocation scheme for mobile ad hoc networks

The issue of certificate revocation in mobile ad hoc networks (MANETs) where there are no on-line access to trusted authorities, is a challenging problem. In wired network environments, when certificates are to be revoked, certificate authorities (CAs) add the information regarding the certificates in question to certificate revocation lists (CRLs) and post the CRLs on accessible repositories or distribute them to relevant entities. In purely ad hoc networks, there are typically no access to centralized repositories or trusted authorities; therefore the conventional method of certificate revocation is not applicable.In this paper, we present a decentralized certificate revocation scheme that allows the nodes within a MANET to revoke the certificates of malicious entities. The scheme is fully contained and it does not rely on inputs from centralized or external entities.     

An Efficient and Scalable Routing for MANETs

Recently, Distributed-Hash-Table (DHT)-based routing protocols have been proposed for large scale mobile ad hoc networks (MANETs). The motive behind using DHT is to avoid/reduce network wide flooding in MANETs in route discovery phase leading to achieve more scalable network. The challenge of deploying DHT at network layer for routing purpose in MANETs is to achieve more matching between logical and physical networks. The paper describes that existing DHT-based routing protocols for MANETs lack this feature. The paper presents a new DHT based scheme [called an efficient and scalable routing for MANETs (ESR)] which reduces the ill-matching between logical and physical networks. This is achieved be distributing the logical identifier (LID) space of DHT structure among the nodes such that the physical neighbors have consecutive LID space portions, i.e. all physical neighbors of a node are also the logical neighbors of the node. Therefore the logical ID space portion of a node may be non-contiguous. Based on this logical structure, a node builds up binary-search-tree (BST) using both logical ID space portion of itself and its neighbors. This BST at the node is traversed to find the next hop for a query/message. Through simulation, the paper shows the proposed approach (ESR) performs better than the existing one in term of routing overhead, average end-to-end delay, path-stretch values and false-negative ratio.     

On the improvement of scaling laws for large-scale MANETs with network coding

This paper investigates the problem of how much benefit network coding can contribute to the network performance in terms of throughput, delay, and storage requirements for mobile ad hoc networks (MANETs), compared to when only replication, storage and forwarding are allowed in relay nodes. We characterize the throughput-delay-storage tradeoffs under different node mobility patterns, i.e., i.i.d. and random walk mobility, with and without network coding. Our results show that when random linear coding instead of replication is used in MANETs, an order improvement on the scaling laws of MANETs can be achieved. Note that previous work showed that network coding could only provide constant improvement on the throughput of static wireless networks. Our work thus differentiates MANETs from static wireless networks by the role network coding plays.     

Stimulating Node Cooperation in Mobile Ad hoc Networks

Mobile Ad hoc Networks (MANETs) rely on the cooperation of nodes for packet routing and forwarding. Much of the existing work in MANETs assume that mobile nodes (possibly owned by selfish users) will follow prescribed protocols without deviation. However, a user may misbehave due to several advantages resulting from noncooperation, the most obvious being power saving. As such, the network availability is severely endangered. Hence, enforcing the cooperation among nodes becomes a very important issue. Several different approaches have been developed to detect non-cooperative nodes or deal with the non-cooperative behavior of mobile nodes in MANETs. These protocols are first surveyed in details in this paper. It is found that the proposed approaches have several concerns that prevent them from really enforcing the node cooperation in MANETs. Thus, a new scheme that can stimulate and also enforce nodes to cooperate in a selfish ad hoc environment is presented. We also present a mechanism to detect and exclude potential threats of selfish mobile nodes. The simulation results indicate that by using the proposed scheme, MANETs can be robust against nodes’ misbehaving and the performance of the network is enhanced many folds when compared to other existing schemes.

Trust prediction and trust-based source routing in mobile ad hoc networks

Mobile ad hoc networks (MANETs) are spontaneously deployed over a geographically limited area without well-established infrastructure. The networks work well only if the mobile nodes are trusty and behave cooperatively. Due to the openness in network topology and absence of a centralized administration in management, MANETs are very vulnerable to various attacks from malicious nodes. In order to reduce the hazards from such nodes and enhance the security of network, this paper presents a dynamic trust prediction model to evaluate the trustworthiness of nodes, which is based on the nodes’ historical behaviors, as well as the future behaviors via extended fuzzy logic rules prediction. We have also integrated the proposed trust predication model into the Source Routing Mechanism. Our novel on-demand trust-based unicast routing protocol for MANETs, termed as Trust-based Source Routing protocol (TSR), provides a flexible and feasible approach to choose the shortest route that meets the security requirement of data packets transmission. Extensive experiments have been conducted to evaluate the efficiency and effectiveness of the proposed mechanism in malicious node identification and attack resistance. The results show that TSR improves packet delivery ratio and reduces average end-to-end latency.     

Distributed Mobility Management for Target Tracking in Mobile Sensor Networks

Mobility management is a major challenge in mobile ad hoc networks (MANETs) due in part to the dynamically changing network topologies. For mobile sensor networks that are deployed for surveillance applications, it is important to use a mobility management scheme that can empower nodes to make better decisions regarding their positions such that strategic tasks such as target tracking can benefit from node movement. In this paper, we describe a distributed mobility management scheme for mobile sensor networks. The proposed scheme considers node movement decisions as part of a distributed optimization problem which integrates mobility-enhanced improvement in the quality of target tracking data with the associated negative consequences of increased energy consumption due to locomotion, potential loss of network connectivity, and loss of sensing coverage.     

Information theoretic framework of trust modeling and evaluation for ad hoc networks

The performance of ad hoc networks depends on cooperation and trust among distributed nodes. To enhance security in ad hoc networks, it is important to evaluate trustworthiness of other nodes without centralized authorities. In this paper, we present an information theoretic framework to quantitatively measure trust and model trust propagation in ad hoc networks. In the proposed framework, trust is a measure of uncertainty with its value represented by entropy. We develop four Axioms that address the basic understanding of trust and the rules for trust propagation. Based on these axioms, we present two trust models: entropy-based model and probability-based model, which satisfy all the axioms. Techniques of trust establishment and trust update are presented to obtain trust values from observation. The proposed trust evaluation method and trust models are employed in ad hoc networks for secure ad hoc routing and malicious node detection. A distributed scheme is designed to acquire, maintain, and update trust records associated with the behaviors of nodes' forwarding packets and the behaviors of making recommendations about other nodes. Simulations show that the proposed trust evaluation system can significantly improve the network throughput as well as effectively detect malicious behaviors in ad hoc networks.     

Improving assurance of a sustainable route-split MANET routing by adapting node battery exhaustion

Assurance networks are designed to realize trustable Internet-Of-Things including terminal devices/infrastructure service applications for new generation networks. To construct assurance networks, it is necessary to evaluate them quantitatively. In this paper, we provide one of case studies to evaluate them quantitatively. In mobile ad hoc networks (MANETs), the network environments change over time due to the movement of nodes, the battery level of nodes, and so on. Assurance networks must maintain high performance even when such diverse changes of the network environments occur in the widely applicable domain. And if their performance degrades, they must early recover from the changes. So far, we have proposed a routing method for MANETs, called Route-Split Routing (RSR). RSR can suppress escalation of control packets in large scale MANETs. However, with RSR, drawbacks occur when some nodes exhaust their batteries. In this paper, we propose a sustainable route-split routing scheme to improve assurance by adapting node faults due to battery exhaustion for MANETs. To evaluate the assurance of the proposed method, we have implemented it with a simulator and have conducted simulation experiments. The results indicate that the proposed method can maintain high throughput when some nodes experience various levels of battery power and power consumption and even when some nodes die simultaneously.     

A simple distributed PRMA for MANETs

With the rapid development of Global Positioning System (GPS) technology and its applications, synchronization between terminals in mobile ad hoc environments becomes feasible at a low cost. Thus, slotted-channel-based medium access control (MAC) schemes like time division multiple access (TDMA) also become interesting for mobile ad hoc networks (MANETs). In this paper, we extend the classical centralized and slotted packet reservation multiple access (PRMA) scheme to a simple distributed PRMA (D-PRMA) as a MAC scheme for MANETs, with emphasis on voice application support. The major efforts of D-PRMA include 1) a simple slot reservation mechanism for voice traffic at the level of "talkspurt" without relying on any central entity and 2) a simple solution for the hidden and exposed terminal problems uniquely present in wireless ad hoc environments. The performance of D-PRMA has been investigated by analysis and computer simulations in comparison with IEEE 802.11. The results show that D-PRMA is much more suitable than IEEE 802.11 for voice application     

Provisioning of adaptability to variable topologies for routing schemes in MANETs

Frequent changes in network topologies caused by mobility in mobile ad hoc networks (MANETs) impose great challenges to designing routing schemes for such networks. Various routing schemes each aiming at particular type of MANET (e.g., flat or clustered MANETs) with different mobility degrees (e.g., low, medium, and high mobility) have been proposed in the literature. However, since a mobile node should not be limited to operate in a particular MANET assumed by a routing scheme, an important issue is how to enable a mobile node to achieve routing performance as high as possible when it roams across different types of MANETs. To handle this issue, a quantity that can predict the link status for a time period in the future with the consideration of mobility is required. In this paper, we discuss such a quantity and investigate how well this quantity can be used by the link caching scheme in the dynamic source routing protocol to provide the adaptability to variable topologies caused by mobility through computer simulation in NS-2.     

Performance of PKI-based security mechanisms in mobile ad hoc networks

Security for ad hoc network environments has received a lot of attention as of today. Previous work has mainly been focussing on secure routing, fairness issues, and malicious node detection. However, the issue of introducing and conserving trust relationships has received considerably less attention. In this article, we present a scalable method for the use of public key certificates and their revocation in mobile ad hoc networks (MANETs). With the LKN-ad hoc security framework (LKN-ASF) a certificate management protocol has been introduced, bringing PKI technology to MANETs. In addition a performance analysis of two different revocation approaches for MANETs will be presented.     

Mobility impact in IEEE 802.11p infrastructureless vehicular networks

Vehicular ad hoc networks (VANETs) are an extreme case of mobile ad hoc networks (MANETs). High speed and frequent network topology changes are the main characteristics of vehicular networks. These characteristics lead to special issues and challenges in the network design, especially at the medium access control (MAC) layer. In this paper, we provide a comprehensive evaluation of mobility impact on the IEEE 802.11p MAC performance. The study evaluates basic performance metrics such as packet delivery ratio, throughput, and delay. An unfairness problem due to the relative speed is identified for both broadcast and unicast scenarios. We propose two dynamic contention window mechanisms to alleviate network performance degradation due to high mobility. The first scheme provides dynamic level of service priority via adaptation to the number of neighboring nodes, while the second scheme provides service priority based on node relative speed. Extensive simulation results demonstrate a significant impact of mobility on the IEEE 802.11p MAC performance, the unfairness problem in the vehicle-to-vehicle (V2V) communications, and the effectiveness of the proposed MAC schemes.     

E2EACK: an end-to-end acknowledgment-based scheme against collusion black hole and slander attacks in MANETs

Mobile ad hoc networks (MANETs) rely on the benevolence of nodes within the network to forward packets from a source node to a destination node. This network construction allows for the forwarding nodes, whether they are selfish or malicious, to drop packets hindering end-to-end communication. In this paper, a new scheme is proposed against collusion black hole and slander attacks in MANETs, named E2EACK. A novel method is used to detect collusion attacks due to collusive malicious nodes which cooperate in the route discovery, but refuse to forward data packets and do not disclose the misbehavior of each other. Contrary to existing methods that detect only collusion black hole attacks, the E2EACK also detects slander attacks and framing attacks. Moreover, the E2EACK uses ACKnowledgment packet to detect malicious nodes on the path and Message Authentication Code (MAC) to authenticate the sender of each data packet. Analytical and simulation results show that the proposed scheme considerably decreases the routing overhead and increases the packet delivery ratio compared to the existing methods.     

Markov Chain Trust Model for Trust-Value Analysis and Key Management in Distributed Multicast MANETs

To increase efficiency in mobile ad hoc networks (MANETs), the multicast MANET is proposed for a sender that sends packets to several receivers through a multicast session. In MANETs, multicast group members frequently change due to node mobility; thus, supporting secure authentication and authorization in a multicast MANET is more critical than that in a wired network with a centralized certificate authentication (CA) server. This paper thus proposes a two-step secure authentication approach for multicast MANETs. First, a Markov chain trust model is proposed to determine the trust value (TV) for each one-hop neighbor. A node's TV is analyzed from its previous trust manner that was performed in this group. The proposed trust model is proven as an ergodic continuous-time Markov chain model. Second, the node with the highest TV in a group will be selected as the CA server. To increase reliability, the node with the second highest TV will be selected as the backup CA server that will take over CA when CA fails. The procedures of the secure authentication for group management are detailed. The security analysis of each procedure is analyzed to guarantee that the proposed approach achieves a secure reliable authentication in multicast MANETs. In addition, several famous attacks have been analyzed and discussed. Numerical results indicate that the analytical TV of each mobile node is very close to that of simulation under various situations. The speed of the convergence of the analytical TV shows that the analyzed result is independent of initial values and trust classes. This is a good feature of analytical models.     

On the Use of Ad Hoc Cooperation for Seamless Vertical Handoff and Its Performance Evaluation

In heterogeneous network environments, it is very important for users to provide seamless services while satisfying quality-of-service, regardless of the connected access network. In this paper, we apply a concept of ad hoc cooperation for the vertical handoff in the heterogeneous network. For the seamless vertical handoff of mobile nodes, a neighbor ad hoc node assists some parts of the handoff procedures requiring large latency, such as authentication and IP registration procedures. Details of the vertical handover operation using the ad hoc cooperation are presented and its performance is evaluated. Numerical results show that the proposed vertical handoff procedure decreases the service disruption time and the probability of packet loss, compared with the conventional handoff methods that do not consider the cooperation of ad hoc node.     

A QoS Routing Protocol with Bandwidth Allocation in Multichannel Ad Hoc Networks

Mobile multimedia applications have recently generated much interest in mobile ad hoc networks (MANETs) supporting quality-of-service (QoS) communications. Multiple non-interfering channels are available in 802.11 and 802.15 based wireless networks. Capacity of such channels can be combined to achieve higher QoS performance than for single channel networks. The capacity of MANETs can be substantially increased by equipping each network node with multiple interfaces that can operate on multiple non-overlapping channels. However, new scheduling, channel assignment, and routing protocols are required to utilize the increased bandwidth in multichannel MANETs. In this paper, we propose an on-demand routing protocol M-QoS-AODV in multichannel MANETs that incorporates a distributed channel assignment scheme and routing discovery process to support multimedia communication and to satisfy QoS bandwidth requirement. The proposed channel assignment scheme can efficiently express the channel usage and interference information within a certain range, which reduces interference and enhances channel reuse rate. This cross-layer design approach can significantly improve the performance of multichannel MANETs over existing routing algorithms. Simulation results show that the proposed M-QoS-AODV protocol can effectively increase throughput and reduce delay, as compared to AODV and M-AODV-R protocols.     

Hypergossiping: A generalized broadcast strategy for mobile ad hoc networks

Broadcasting is a commonly used communication primitive needed by many applications and protocols in mobile ad hoc networks (MANET). Unfortunately, most broadcast solutions are tailored to one class of MANETs with respect to node density and node mobility and are unlikely to operate well in other classes. In this paper, we introduce hypergossiping, a novel adaptive broadcast algorithm that combines two strategies. Hypergossiping uses adaptive gossiping to efficiently distribute messages within single network partitions and implements an efficient heuristic to distribute them across partitions. Simulation results in ns-2 show that hypergossiping operates well for a broad range of MANETs with respect to node densities, mobility levels and network loads.     

A technique to improve network lifetime in mobile ad hoc networks

Energy is an important issue in mobile ad hoc networks (MANETs), and different energy‐aware routing mechanisms have been proposed to minimize the energy consumption in MANETs. Most of the energy‐aware routing schemes reported in the literature have considered only the residual battery capacity as the cost metric in computing a path. In this paper, we have proposed, an energy‐aware routing technique which considers the following parameters: (i) a cost metric, which is a function of residual battery power and energy consumption rate of participating nodes in path computation; (ii) a variable transmission power technique for transmitting data packets; and (iii) To minimize the over‐utilization of participating nodes, a limit is set on the number of paths that can be established to a destination through a participating node. The proposed scheme is simulated using Qualnet 4.5 simulator, and compared with Ad hoc On‐Demand Distance Vector (AODV) and Lifetime Enhancement Routing (LER). We observed that the proposed scheme performs better in terms of network lifetime and energy consumption. Copyright © 2014 John Wiley & Sons, Ltd.     

Predictive and Fault-Tolerant Location Service in Mobile Ad Hoc Networks

Using location information to help routing is often proposed as a means to achieve scalability in large mobile ad hoc networks (MANETs). One of the biggest challenge in geographic routing protocols is the design of efficient distributed location services that can locate the positions of mobile nodes. The accurate positioning of mobile nodes in MANETs is important to location service scheme since they are related to efficiency of routing protocols. We propose a grid-based predictive Location Service (GPLS) scheme and a hole-tolerant grid-based predictive Location Service (GPLS-H) scheme. In proposed location service scheme GPLS and GPLS-H, the network is partitioned into grids and grids are divided into groups by using a HASH function, which guarantees the uniform distribution of location servers of a node in the network. The main contribution of this paper is that the proposed location service scheme GPLS and GPLS-H provide accurate location query capability by means of location prediction of mobile nodes and GPLS-H can tolerate the “holes” in grid networks. The simulation results show that the location service scheme GPLS and GPLS-H have better performance than CRLS and SLURP in query success ratio, query delay and location availability.