2011

A Novel Framework of Adaptive Routing Design in Cognitive Radio Military Networks

With advanced wireless communication and networking technologies, cognitive radio ad hoc networks (CRAHNs) promise to revolutionize next generation military networks. In this paper, we propose a framework of adaptive routing design (ARD) in CRAHNs with time-varying availability of links. ARD includes a novel topology formation component and a routing scheme. The topology formation component forms a weighted directional graph model for the physical network and adapts it to time-varying changes of network links. Based on the graph model, the routing scheme computes optimal routing paths for a pair of nodes. An optimal routing path between a pair of nodes has the smallest hop count after minimizing the adjacent hop interference. ARD also takes into account effects due to the number of pre-defined radio interfaces in each node as well as overall network traffic load. Concrete examples are given to demonstrate the adaptiveness and performance of the proposed adaptive routing design framework. Computational complexity analysis and preliminary simulation results show that the proposed routing design is more computationally efficient than an existing routing algorithm in cognitive radio networks. More importantly, to accommodate the time-varying changes of the availability of links, the proposed routing design only requires incremental updates on the global network graph without regenerating the entire graph. This incremental graph updating procedure provides an efficient routing design and implementation solution for cognitive radio networks with link availability varying over time.

Packet Delay in Networked Multi-UAV Systems

In this paper, we conduct analysis of packet delay in a networked multi-UAV system. In the system, each UAV runs the distributed coordination function (DCF) of IEEE 802.11 at the medium access control (MAC) layer. All UAVs in the networked system are one-hop neighbors, and a pair of UAVs can communicate over the wireless channel using a fixed data rate. A light traffic condition is used (i.e., in each UAV, data packets are generated one at a time and the interval between two successive generation times is described by independent random variables following an exponential distribution with some fixed mean). By modeling each UAV to be an M/M/1 queueing system, we first derive the mean packet delay under light traffic conditions. Numerical and simulation results show that the mean packet delay derived in this paper is accurate for a networked multi-UAV system under the light traffic condition. It increases with either the number of UAVs in the system or the packet generation rate. In addition, existing results in the literature, based on the saturated traffic condition (i.e., packets are always supplied for transmission), tend to overestimate by a large amount the mean packet delay for networks with light traffic. In the second part of this paper, we apply simulation data to the analysis of the probability distribution function of the packet delay. Using a distribution fitting tool, we observe that the packet delay can be better approximated by the sum of a deterministic delay and a random delay. The deterministic delay corresponds to the time period during which the node senses the medium and is able to perform a successful transmission, while the random delay follows a Gamma distribution function.

Routing Schemes for Cognitive Radio Mobile Ad Hoc Networks

In this chapter, we propose a classification of existing routing schemes for cognitive radio mobile ad hoc networks (CR-MANETs) and review these representative CR-MANET routing schemes. Then, we describe a CRMANET model and present a novel adaptive routing design for the CR-MANET, referred to as ARDC, algorithmically and through examples. ARDC is based on the graph modeling approach, and its most significant contribution is that ARDC adapts to dynamic changes in the network topology much more computationally efficient than other CRMANET routing schemes. At last, some further research directions on CR-MANET routing are identified.

A New Cryptography Scheme for Selective Broadcasting.

We propose a new cryptography scheme that allows for selective broadcasting and precludes collusion between malicious nodes located inside the intended broadcast group as well as outside of the group. In our scheme, the decryption key for each node is customized and embeds personal information inherent to each node. Compared to the Attribute-based encryption approach (ABE) where the nodes satisfying a predefined set of attributes can decrypt a message, our scheme allows for the customization of each node's decryption key based on private information about a node. This approach discourages users to openly reveal their private information and disclose their private keys. Our scheme can achieve a constant ciphertext size regardless of the number of users in the broadcast group. We also present the storage overhead consideration and discuss some potential applications of this cryptography scheme.

On the Selection of Cluster Heads in MANETs.

Clustering schemes offer a practical way of providing scalability when dealing with large and dense Mobile Ad hoc Networks (MANETs). The feasibility of a clustering method can be primarily determined by the complexity of the cluster head selection. Optimizing the cluster head selection allows for the network to be more efficient by minimizing the signaling overhead while ensuring that the network connectivity is maintained despite topology changes. In this paper, we investigate the problems of cluster head selection for large and dense MANETs. Two variants of the cluster head selection are examined: (1) the distance-constrained selection where every node in the network must be located within a certain distance to the nearest cluster head; and (2) the size-constrained selection where each cluster is only allowed to have a limited number of members. We show that the problem of minimizing the set of cluster heads is NP-hard for both variants. We propose two distributed selection algorithms, each having logarithmic approximation ratio, for these variants. We also discuss, using simulations, the resulting cluster size distribution and cluster head density, which impact the efficient operation of the network.

New Findings on the Complexity of Cluster Head Selection Algorithms

Clustering schemes offer a practical way of providing scalability when dealing with large and dense Mobile Ad hoc Networks (MANETs). The feasibility of a clustering method can be primarily determined by the complexity of the cluster head selection. Optimizing the cluster head selection allows for the network to be more efficient by minimizing the signaling overhead while ensuring that the network connectivity is maintained despite topology changes. In this paper, we present some new findings on the complexity of the cluster head selection algorithms. Two variants of the cluster head selection are examined: (1) the distance-constrained selection where every node in the network must be located within a certain distance to the nearest cluster head; and (2) the size-constrained selection where each cluster is only allowed to have a limited number of members. We show that the problem of minimizing the set of cluster heads is NP-hard for both variants. We propose two distributed selection algorithms, each having logarithmic approximation ratio, for these variants. We also discuss, using NS-2 simulations, the resulting cluster size distribution and cluster head density, which impact the efficient operation of the network.

Mobile Beacon Based Localization Approaches for SASNet

In this report, novel localization approaches based on the use of a mobile beacon are presented for the Self-healing Autonomous Sensor Network (SASNet) project, a Defence R&D Canada (DRDC) Technology Demonstration Project (TDP) under joint development by the Communications Research Centre (CRC) and DRDC. The mobile beacon can be carried by a deploying person during the stage of sensor deployment while broadcasting beacon signals. Each sensor node is equipped with a receiver module for receiving the beacon signals. Any node that is within the transmission range of the mobile beacon can estimate its distance to the mobile beacon based on the contents of the beacon signals. The use of a mobile beacon can greatly simplify the process of sensor localization, and help to overcome mitigate many of the difficulties that would be encountered by other localization approaches. Four localization approaches, referred to as MLE, LLS, MDS and MAP, are proposed based on the maximum likelihood technique, the linear least squares method, the multidimensional scaling technique and a local map registration approach, respectively. These approaches all rely on the use of a mobile beacon, and are designed to operate without requiring the process of path planning for the mobile beacon. MLE and LLS are distributed localization approaches while MDS and MAP have centralized architectures. MLE and LLS require that the mobile beacon know its coordinates. On the other hand, MDS and MAP compute relative locations of the sensor nodes, and do not require the location information of the mobile beacon, making them attractive for applications where access to GPS signals is not available. Finally, computer simulations are used to evaluate the localization performance of the proposed approaches under different scenarios. The simulation results are analyzed and conclusions are presented.

2010

Packet Delay in Wi-Fi Networks of Unmanned Aerial Vehicles

An important but challenging problem in multiple unmanned aerial vehicle (UAV) cooperative control systems is how the UAVs should be networked over the wireless medium so that information can be transmitted in near real-time. In this memorandum, we conduct a statistical analysis of the packet end-to-end delay in a Wi-Fi network of UAVs. In the network, each UAV runs the distributed coordination function (DCF) of IEEE 802.11 at the medium access control (MAC) layer. All UAVs are one-hop neighbors, and a pair of UAVs can communicate over the wireless channel using a fixed data rate. A light traffic condition is used (i.e., in each UAV, data packets are generated one at a time and the interval between two successive generation times is described by independent random variables following an exponential distribution with some fixed mean). By modeling each UAV to be an M/M/1 queueing system, we first derive the mean packet end-to-end delay under light traffic conditions. Numerical and simulation results show that the mean packet end-to-end delay derived in this memorandum is accurate for Wi-Fi networks under the light traffic condition. It increases with either the number of UAVs in the network or the packet generation rate. In addition, existing results in the literature, based on the saturated traffic condition (i.e., packets are always supplied for transmission), tend to overestimate by a large amount the mean packet end-to-end delay for networks with light traffic. In the second part of the document, we apply simulation data to the analysis of the probability distribution function of the packet end-to-end delay. Using a distribution fitting tool, we observe that the packet end-to-end delay can be better approximated by the sum of a deterministic delay and a random delay. The deterministic delay corresponds to the time period during which the node senses the medium and is able to perform a successful transmission, while the random delay follows a Gamma distribution function.

Probabilistic Analysis of Resequencing Queue Length in Multipath Packet Data Networks

In multipath packet data networks, packets may reach the receiver out-of-sequence, i.e., packets arrive at the receiver in a sequence different from their egressing order at the transmitter. In practice, however, many applications require an in-sequence packet delivery, meaning that packets need to be delivered to an application on the receiver in their original order at the transmitter. The in-sequence packet delivery is usually implemented through the approach of packet resequencing. In this paper, a multipath data network with packet resequencing is modeled and the asymptotic properties of the steady-state probability distribution of the resequencing queue length are studied. The assumptions used are that the packets sent from the transmitter according to a Poisson process, and the transmission period of a packet along a route follows an exponential distribution. An asymptotic distribution function of the resequencing queue length is derived for a large queue length in the steady state of the network. Numerical and simulation examples are presented to validate the derived result. Through comparisons of large deviation and asymptotic values of the resequencing queue length distribution, we show that the asymptotic result provides a better approximation to the distribution function of the resequencing queue length than the large deviation result reported in the literature.

Analysis of One-Hop Packet Delay in MANETs over IEEE 802.11 DCF

In mobile ad hoc networks (MANETs), the estimation of packet end-to-end delay depends on that of one-hop packet delay. In this paper, we conduct an analysis of the one-hop packet delay in MANETs, where the medium access control (MAC) layer uses the IEEE 802.11 distributed coordination function (DCF) to share the medium. In the MANET, each node runs the IEEE 802.11 DCF and a routing protocol. It is assumed that all nodes are one-hop neighbors, and that any pair of nodes can send data over the wireless channel with a fixed data rate. The light traffic condition is used, i.e., each node generates packets at the network layer according to a Poisson process. By modeling each wireless node as an M/M/1 queueing system, we derive the mean one-hop packet delay analytically under the light traffic condition. Simulation analysis is carried out to verify the derived results. Results show that the mean one-hop packet delay increases with either the network size or the packet generation rate in networks subject to the light traffic condition. The mean one-hop packet delay derived in this paper is analytical and exact for networks under the light traffic condition. Results that can be found in the literature are usually based on the heavy traffic condition, and they tend to overestimate by a large amount the mean one-hop delay for networks with light traffic.

ARQ Schemes in Wireless Multi-Channel Communication Systems: Modeling and Performance Evaluation

With rapid advances in wireless communication and networking, orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output antennas (MIMO) are often adopted in communication systems to create multiple parallel channels. To implement error control through retransmission of packets in a multichannel communication system, Automatic-Repeat-reQuest (ARQ) schemes have been generalized for parallel multichannel data communications. In this thesis, we develop two stochastic systems, denoted by MSW-ARQ and MSW-ARQ-inS, for modeling stop-and-wait ARQ over multiple channels with either time-invariant or time-varying error rates. We evaluate their performance analytically and through simulation. With a time-invariant error rate for each channel, we derive the distribution function of the packet delay for both stochastic systems. Meanwhile, we analyze the probability generating function of the resequencing buffer occupancy and the distribution function of the resequencing delay for MSW-ARQ-inS. By assuming a time-varying error model, we obtain statistical properties of the resequencing buffer occupancy and the resequencing delay for MSW-ARQ-inS. Based on results from the analysis, we numerically compute the probability mass functions of the resequencing buffer occupancy, the resequencing delay, and the packet delay for selected values of system parameters, from which the system performance is evaluated. From numerical and simulation results, we identify trends in the mean resequencing buffer occupancy, the mean resequencing delay and the mean packet delay as functions of system parameters. We confirm that the optimal packet transmission scheduling under the throughput standard is also optimal under the delay criterion. We expect that the modeling technique and analysis approach proposed in this thesis can be applied to the performance evaluation of other ARQ protocols (e.g., selective-repeat ARQ) over multiple channels.

On the Probability Distribution of Join Queue Length in a Fork-Join Model

In this paper, we consider the two-node fork-join model with a Poisson arrival process and exponential service times of heterogeneous service rates. Using a mapping from the queue lengths in the parallel nodes to the join queue length, we first derive the probability distribution function of the join queue length in terms of joint probabilities in the parallel nodes, and then study the exact tail asymptotics of the join queue length distribution. While the asymptotics of the joint distribution of the queue lengths in the parallel nodes have three types of characterizations, our results show that the asymptotics of the join queue length distribution are characterized by two scenarios: (1) an exact geometric decay and (2) a geometric decay with the pre-factor $n^{-1/2}$.

Modeling and Analysis of Resequencing Delay in SR-ARQ

In selective repeat automatic repeat request (SR-ARQ) used by a transmitter-receiver pair, data packets correctly received by the receiver need to be delivered to its upper-layer protocol in the same order as they arrived at the transmitter from its upper-layer protocol. In this paper, we propose a novel discrete-time priority queueing network to model SR-ARQ, and study the performance of the resequencing buffer in terms of the mean packet resequencing delay when packets arrive to the network according to a Bernoulli process. Based on the stationary probability distribution of an embedded Markov chain, we derive an explicit expression for the mean packet resequencing delay. Numerical and simulation results of the mean resequencing delay are presented and some performance trends are discussed. This paper presents an analytic framework for accurately computing the mean packet resequencing delay caused by packet retransmission in data communication networks. The proposed discrete-time priority queueing network model is expected to be used for performance analysis of ARQ protocols with a more general packet arrival process.

Experiments and analysis of stand-alone GPS for relative location discovery for SASNet

In this report, we use experimental data to study the performance of stand-alone Global Positioning System (GPS) for relative location discovery for the Self-healing Autonomous Sensor Network (SASNet) project. The objective is to seek if stand-alone GPS measurements from inexpensive GPS receivers can result in the relative positioning accuracies desired by wireless {\it ad hoc} sensor network applications. The relative locations are obtained by comparisons of stand-alone global GPS position fixes. In this study, various sensor deployment scenarios are used that are representative of the real operational conditions of SASNet, which vary from minimal to heavy canopy cover and multipath effects around urban canopy and buildings. The ground truth sensor node locations are estimated by measuring the internode distances between all the sensor nodes and applying the multidimensional scaling (MDS) technique. The analysis is based on the approach of Procrustes analysis. Based on the results, conclusions are made about the suitability of stand-alone GPS as a localization tool in wireless sensor networks.

Optimal local map registration for wireless sensor network localization problems

In this chapter, we present an optimal local map registration algorithm for constructing global maps from local relative maps for wireless network localization applications. A wireless network is partitioned into sub-networks with overlapping or common nodes that shared by different sub-networks. Local maps are built for each sub-network, which consist of the relative coordinates of nodes in each network. The local maps are then transformed into a global map using a set of affine transforms with each consisting of a rotation, a reflection and a translation for each individual local map. The optimal transform is found by minimizing the discrepancies, in the global map, of the common sensor nodes shared by different local maps. A computationally efficient gradient projection algorithm is developed for finding the optimal transforms. The local map registration approach can solve many of the problems encountered by pairwise map merging based techniques and is able to achieve global optimal performance. More importantly, the technique provides a systematic approach for constructing global maps from local maps. Computer simulations are used to demonstrate the performance and effectiveness of the proposed algorithm.

Reliable Transport Protocol for SASNet Level-1 Network: Requirements, Literature Survey & Simulation/Evaluation of a Candidate Protocol

In recent years, sensor networks have been widely studied in the research community. Miniaturization of processing units combined with increases in processing speed, improvements in battery technologies and advances in low power wireless technologies have enabled the feasibility to develop innovative networks composed of tens or hundreds of small sensors forming an ad hoc network. Such networks have constraints that are typically not found in regular wired or wireless networks: low memory devices, low processing speed devices, energy-constrained devices, etc. In the IETF jargon, there is a name for such networks: L2N, for "low power, lossy networks". In this context, the term "low power" is used to describe the devices of the network, and "lossy" is used to qualify the links of the network. All these characteristics of L2N force designers to re-think the networking aspect of communications (addressing, routing protocol, MAC and link layer protocol, etc). In this document, we investigate solutions for the transport protocol of SASNet. The main target is to provide reliable unicast and broadcast in level-1 networks (i.e. the sensor nodes network). The second objective is to provide reliable broadcast in level-2 network as well - ideally using the same solution as in level-1 network. This document starts with a discussion on the design goals directly derived from the requirements. The next section explains why the widely used TCP and UDP protocols are unsuitable for this particular application. Next, different approaches proposed in the research community are introduced, explained and compared. The most promising one is simulated for performance analysis. Finally, the document concludes with recommendations for implementation of a transport protocol for SASNet.

MAC Protocols for UAV MANET - 2008-2009 Survey

This document is the result of a vast survey of MAC protocols found in the literature that offers some desirable characteristics for UAV MANETs. The survey was done in late 2008 and 2009. It is important to note that the amount of research publications in MAC protocols for wireless and MANET networks is tremendous. This contrast with the amount of research done in the area of UAV MANET MAC protocols: there is almost none. This too contrasts with the huge amount of literature in the area of UAV in general (in the topics of navigation and physical & material construction). From the 1970s until now there have been a large number of publications covering the topic of MAC layers for wireless networks and MANETs. It would be unrealistic to summarize everything published in this area; it would also be unrealistic to say that we reviewed everything on the topic. Anyway, throughout the years, real innovations were rare, and most of the literature represents flavours or adaptation of previous paradigms. Also, UAV MANET are a special type of MANET, therefore many MAC protocols developed for either wireless networks or MANET aren't well suited for UAV MANET. However, some key technologies and ideas can be retained from protocols not entirely suited for the needs of UAV MANET MAC protocol. This document will summarize the publications that we judged pertinent to meet our objectives. It is not so surprising that there is very little in the literature about MAC layers for UAV MANET. First of all, most of the research in the area of UAV has focused on the navigation system or on the physical construction of the UAV. Second, until recently it was not practically envisaged to have UAV operate cooperatively (and therefore forming a MANET, from a communications perspective). Most UAVs were designed to operate in solo, and so was their communication system. It is worth noting at this point that this document concentrates only on the communication between the UAVs. This document does not consider the link to a ground crew or base station. It is assumed that this link will be assured though another communication link, perhaps through conventional MOTS (no research to be done here - this problem has been seen and solved before). Even though the requirements for UAV MANET MACs are unique, they share some characteristics with MAC layers designed for vehicular application (typically called VANET) and some tactical network. Therefore, the survey included these, whenever pertinent. A MAC protocol is normally implemented directly on top of the physical layer, according to the OSI network layers (which we can say is a widely accepted design paradigm, except for some rare particular cases). Although ideally the MAC layer should be totally independent from the radio (i.e. the physical layer), practically this is not true. A MAC layer that operates on a multi-channel radio will also incorporate in its protocol the intelligence necessary to determine on which channel to access the medium at a certain point in time and in a given context. Although at the packet level (in term of collision management) the medium access may be the same regardless of the type of radio, from a global medium access it is different. Because at this point we are still debating on the type of radio that we envisage will be onboard UAVs in the future, we look at both approaches. This survey covers first MAC layers for single channel radios, and it follows with multiple channels radios. This document is organized as follows. Section 2 describes the requirements. Section 3 briefly describes the classes of MAC protocols. Section 4 present a survey of pertinent MAC protocols designed for single channel radio. Section 5 does the same for multi-channel and cognitive radios. Section 6 discusses the survey and prepares the table for future design considerations. Finally, Section 8 concludes the document.

The Design of a MAC Protocol for UAVs and Military Tactical Networks

This document presents the design of a MAC layer tailored to the needs of convoy or UAV applications. The MAC must therefore operate in a MANET environment with all the typical characteristics associated to it, but with extra requirements specific to the UAV and convoy operations in term of low latency and high bandwidth. The MAC layer presented in this document assumes a CDMA physical layer capable of multiuser detection. Multiuser detection allows a receiver to receive simultaneously signals coming from different transmitters, and yet be able to successfully decode each of them. This is drastically different from traditional radios, where receivers only decode one single signal at a time. Because with CDMA the MAI (Multiple Access Interference) problem must be resolved in order to achieve the desired performance and spatial re-use, the MAC layer proposed here includes a power management scheme that considers this issue. The foundation of the MAC layer proposed in this document is inspired from earlier work by J. Zhang et al at the "École de Technologie Supérieure" University in Montréal (ETS). The design proposed here is the result of collaboration between the ETS, the "Communications Research Centre Canada" (CRC), an Agency of Industry Canada and Olfa Ben Sik Ali, associated with the "École Polytechnique de Montréal". This document starts in section 2 with an overview of the proposed MAC protocol, and follows by the details of each module.

Research in Ad hoc & Sensor Network Systems, CRC: An Emulator to Test MANET Protocols

The purpose of this document is to describe the testbed that is used to test MANET protocols by the Research in Ad hoc & Sensor Network Systems group at CRC. The goal of the document to explain the testbed, and describe what remains to be done on it to make it fully operational for researchers of the Mobile Ad hoc & Sensor Network Systems group at CRC, planned. It is planned to work on the implementation of the testbed in 2009-2011. This document will explain from a high level view how the new testbed operates. We first start by a brief overview of the testbed that is used since 2003, and then we continue by explaining the future version of the testbed, that is planned to be implemented by 2009-2011. The requirements for enhanced testbed come from different specific projects and also from the general nature of our research group. For example, in DRDC project 13QK, a MANET of UAV needs to be implemented to test application and networking protocols. In general, since the Research in Ad hoc & Sensor Network Systems group at CRC deals with MANET in many other current and future projects, it is envisaged that the testbed will be used for many years to come, as did the previous one. Therefore, careful planning is essential to have a versatile MANET emulator testbed.

Selective Diffusion of Ratings in Trust Propagation for MANETs

In mobile ad hoc networks (MANET), existing multicast protocols are regularly used by nodes to propagate information. The usual objective of these protocols is to efficiently deliver the information to a large number of subscribed nodes. However, in some circumstances, there may be a need to prevent some nodes from acquiring sensitive information during the broadcast. It becomes even more disruptive and challenging if we assume that nodes can collude and mutually share the information they received. We propose in this paper a key distribution and encryption scheme that allows nodes to selectively diffuse some information into the network and to prevent key sharing due to malicious nodes collusion. While the key computation and distribution are provided by a centralized server at the network configuration phase, encryption and decryption are performed by nodes in a distributed manner during the network operations. We illustrate the use of such a selective diffusion protocol with the propagation of trust ratings in a MANET. The selective diffusion of trust ratings will impact mission success by providing a mechanism to monitor the true state of the network and therefore improve users' awareness.

2009

Detection of wormhole attacks based on hypothesis testing for wireless ad hoc networks

In this paper, a new technique for detecting wormhole attacks based on distance verification and the use of hypothesis testing has been presented. The use of hypothesis testing for distance verification is able to provide statistical performance measures for the proposed wormhole detection solution. The proposed technique was shown to be computationally efficient. The implementation of the OLSR protocol was discussed and it was shown that only minor modifications were required and no extra communication overhead was introduced. A simple collaborative decision-making strategy was proposed to counter the limitations of distance verification by a single node. Computer simulations were carried out and demonstrated the effectiveness of the proposed wormhole detection technique. It should be noted that, the proposed wormhole attack detection approach does not rely on a particular ranging method. Although RSS ranging was discussed in this paper, other ranging techniques are equally applicable such as ultrasound ranging. In fact, the other ranging techniques are expected to result in better detection performance due to their higher range accuracy.

Analysis of Stand-Alone GPS for Relative Location Discovery in Wireless Sensor Networks

In this paper, we use experiments to examine the accuracy of stand-alone Global Positioning System (GPS) for relative location discovery in wireless sensor networks. The relative locations are obtained by comparison of stand-alone global GPS position fixes. We seek to find out if stand-alone GPS measurements from inexpensive GPS receivers can result in the relative positioning accuracies desired. Various sensor deployment scenarios are used that are representative of the real operational conditions of wireless sensor network applications. The ground truth sensor node locations are estimated by measuring the internode distances between all the sensor node and applying the multidimensional scaling (MDS) technique. The analysis is based on the approach of Procrustes analysis. An optimal rigid transformation is obtained using a least squares method to estimate the root mean square errors of the GPS relative positions. Based on the results, conclusions are made about the suitability of stand-alone GPS as a localization tool in wireless sensor networks.

SASNet Sensor Localization System Design Considerations

Sensor localization is a necessary prerequisite of SASNet for target detection and tracking in monitoring and surveillance application. It also helps to uncover and heal coverage holes during the stage of SASNet sensor deployment. A mobile beacon based localization technique has been proposed for SASNet based on a mobile beacon and the use of a multilateration technique. This report discusses the design considerations for SASNet localization technique including hardware, approach and sensor deployment strategies. An implementation of localization functions on sensor nodes, fusion node and hand-held device is demonstrated using a message sequence chart. Some practical implementation issues are also discussed in the report.

Hierarchical OLSR draft-lacharite-manet-holsr-02

This document describes the hierarchical Optimized Link State Routing (HOLSR) mechanism for heterogeneous mobile ad hoc networks. In this specification a heterogeneous mobile ad hoc network is defined as a network of mobile routers that are characterized by different communication capabilities, such as communication channels, processing powers and energy levels. The HOLSR mechanism is an extension to the OLSRv2 protocol. HOLSR takes advantage of router's distinct communications capabilities to reduce the routing control overhead in large heterogeneous ad hoc networks, thus improving the performance of the routing mechanism. More precisely, HOLSR defines a hierarchy in the network and presents a routing scheme for this hierarchical structure with a better scalability.

Analysis of the Impact of Swarm Mobility on Performance of Routing Protocols in MANETs

In a mobile ad-hoc network (MANET), node mobility has a significant impact on the performance of routing protocols. Most of the previous research has been focused on entity mobility models, i.e., movements of the mobile nodes are independent of each other. In this paper, we investigate the impact of swarming behavior of mobile nodes, as observed in many mobile networks, on the performance of MANET routing protocols. The effects of coordinated movements of mobile nodes are characterized by using a Markov chain, through which a quantized collaboration degree is defined. Based on the swarm mobility model, we analyze the probabilistic properties of hop count as a complement to those analytical studies on packet delay performance. With a medium access control model, we derive an upper and a lower bound of routing overhead for MANET proactive routing protocols. Simulations are used to demonstrate the validity of the derived analytical expressions. Numerical and simulation results show that more coordinated movements of the nodes reduce the number of control packets required to be disseminated over the network, and in turn the routing overhead.

Packet delay analysis for multichannel communication systems with MSW-ARQ

In this paper, we perform modeling and analysis of the packet delay for a multichannel stop-and-wait automatic-repeat-request protocol (MSW-ARQ). In this protocol, the transmitter retransmits an erroneously received packet as well as all transmitted packets with larger sequence numbers than that associated with the erroneously received one. For this protocol, under the assumption that all parallel channels have the same transmission rate but possibly different error rates, we propose a method of analyzing the steady-state probability distribution function of the end-to-end delay, referred to as the packet delay, of an arbitrary packet. To demonstrate the generality of the proposed method, we further apply it to the packet delay analysis for a revised multichannel stop-and-wait ARQ protocol, referred to as MSW-ARQ-inS, in which only the erroneously received packets will be retransmitted. From expressions obtained through the analysis, numerical results are presented for chosen values of the number of channels and the error rates, based on which we conclude that MSW-ARQ-inS outperforms MSW-ARQ in terms of the mean packet delay performance. We also identify the performance trends of the mean packet delay with respect to system parameters. It is observed that the greater the variance in the error rates, the smaller the mean packet delay in both MSW-ARQ and MSW-ARQ-inS. Meanwhile, the number of parallel channels has only an insignificant impact on the mean packet delay, from which we conclude that the use of parallel channels is a favorable option to significantly increase the data transmission rate while keeping the mean packet delay at an acceptable level.

Resequencing Analysis of Stop-and-Wait ARQ for Parallel Multichannel Communications

In this paper, we consider a multichannel data communication system in which the stop-and-wait automatic-repeatrequest protocol for parallel channels with an in-sequence delivery guarantee (MSW-ARQ-inS) is used for error control. We evaluate the resequencing delay and the resequencing buffer occupancy, respectively. Under the assumption that all channels have the same transmission rate but possibly different time-invariant error rates, we derive the probability generating function of the resequencing buffer occupancy and the probability mass function of the resequencing delay. Then, by assuming the Gilbert-Elliott model for each channel, we extend our analysis to time-varying channels. Through examples, we compute the probability mass functions of the resequencing buffer occupancy and the resequencing delay for time-invariant channels. From numerical and simulation results, we analyze trends in the mean resequencing buffer occupancy and the mean resequencing delay as functions of system parameters. We expect that the modeling technique and analytical approach used in this paper can be applied to the performance evaluation of other ARQ protocols (e.g., the selective-repeat ARQ) over multiple time-varying channels.

OSPF Multipoint Relay (MPR) Extension for Ad Hoc Networks

This document specifies an OSPFv3 interface type tailored for mobile ad hoc networks. This interface type is derived from the broadcast interface type, and is denoted the "OSPFv3 MANET interface type".

On Trust Evaluation in Mobile Ad hoc Networks

Trust has been considered as a social relationship between two individuals in human society. But, as computer science and networking have succeeded in using computers to automate many tasks, the concept of trust can be generalized to cover the reliability and relationships of non-human interaction, such as, for example, information gathering and data routing. This paper investigates the evaluation of trust in the context of ad hoc networks. Nodes evaluate each other's behaviour based on observables. A node then decides whether to trust another node to have certain innate abilities. We show how accurate such an evaluation could be. We also provide the minimum number of observations required to obtain an accurate evaluation, a result that indicates that observation based trust in ad hoc networks will remain a challenging problem. The impact of making networking decisions using trust evaluation on the network connectivity is also examined. In this manner, quantitative decisions can be made concerning trust-based routing with the knowledge of the potential impact on connectivity.

Implementation and Performance Evaluation of a Quality of Service Support for OLSR in a Real MANET

Military applications in tactical networks have quality of service (QoS) requirements. The purpose of this paper is to show that these requirements can be fulfilled by our QoS support mechanisms, implemented in a MANET based on the IEEE802.11b and the OLSR protocols. After a brief presentation of our solution, we describe its implementation on a MANET testbed made of 18 routers. Results of performance evaluation obtained from measurements are reported and compared with simulation's. They allow to conclude that this QoS support improves the quality perceived by the users in terms of delivery rate and granted throughput.
The flooding optimization present in OLSR is also preserved. With QoS support, simulation results show that the network is able to admit more user flows than without it. The over-head of this QoS support is evaluated and extensive simulations also show that it is scalable to large networks.

2008

An Optimal Local Map Registration Technique for Wireless Sensor Network Localization Problems

In this paper, we present an optimal local map registration algorithm for constructing global maps from local relative maps for wireless sensor network localization applications. In the algorithm, local maps are transformed into a global map using a set of affine transforms with each consisting of a rotation, a reflection and a translation for each individual local map. The optimal transform is found by minimizing the discrepancies, in the global map, of the common sensor nodes shared by different local maps. A computationally efficient gradient projection algorithm is developed for finding the optimal transforms. The local map registration approach can solve many of the problems encountered by pairwise map merging based approaches and is able to achieve global optimal performance. It provides a systematic approach for constructing global maps from local maps. Computer simulations are used to demonstrate the performance and effectiveness of the proposed algorithm.

A Simple and Efficient Detection of Wormhole Attacks

Wormhole attacks in mobile ad hoc networks (MANET) have long been considered a serious threat to MANET's routing. Most of the existing proposals rely on GPS devices and require that the node's clocks are synchronized. Such constraints naturally lead to limitations of applicability since GPS does not operate well in obstructed areas, and clock synchronization in MANET is not always accurate. In this paper, we propose an efficient and simple way to detect wormhole attacks, using a technique called reference broadcast. GPS devices are not required, and clocks do not need to be synchronized. In fact, no particular assumption is made on the communication equipment. We show that our solution can be easily implemented, using either the well-known routing protocol OLSR or any neighbor discovery protocol. Our solution also exhibits a high degree of accuracy in detecting wormhole attacks.

A Trust-Based Security Architecture for Tactical MANETs

Security is a main concern in the establishment of tactical MANETs. Literature is abundant in defining protocol extensions to provide more secure MANET communications. Also many techniques have been developed to identify different types of network attacks, such as the wormhole attack, for example. However, all these security solutions are designed for specific routing protocols. In the absence of a generic security architecture, nodes from different MANET domains cannot cooperate and benefit from security advantages across the entire network, such as secured inter-domain routing, etc. In this paper, we present a general architecture for a security trust monitoring layer that runs on top of routing protocols. This security layer can be applied to different MANET routing protocols and provide monitoring of different network attacks by adding specific plug-ins. Our modular security approach allows nodes, running different routing protocols and equipped with different security solutions, to inter-operate by exchanging security information with each other. The idea is to have a security layer monitor MANET communications and construct a trust representation model of member nodes of the MANET. The trust information gathered can be communicated to MANET nodes (upon request), and such nodes can modify their routing tables accordingly. We show that this security architecture can be implemented on a real MANET test bed. As an example of security attack, we also show the integration of wormhole detection and counter-measure with the security trust monitoring layer performed on this same test bed.

Interconnecting OLSRv2 and OSPF

We design in this paper the mechanisms for interconnecting nodes running OLSRv2 andOSPF protocols, both are link state routing protocols. Nodes, however, are unable to route packets between OLSRv2 and OSPF domains without an OLSRv2-OSPF gateway. This paper makes use of internal mechanisms, well-defined in OLSRv2 and OSPF to design such a gateway.

Constrained Linear Least Squares Approach for TDOA Localization: A Global Optimum Solution

In this paper, we formulate the time-difference-of-arrival (TDOA) emitter localization problem as a constrained linear least squares problem. We show that the nonlinear least squares problem has a unique global minimum and a computationally efficient algorithm is developed for finding the emitter location estimates that corresponds to the global minimum. The approach is robust and more resilient to moderate and large sensor measurement noise than other existing location techniques. Computer simulations are used to demonstrate the effectiveness and performance of the proposed algorithm..

2007

A Simplified Approach to Multicast Forwarding Gateways in MANET

Simplified Multicast Forwarding (SMF) provides an optimized flooding mechanism in MANET environments to efficiently propagate multicast packets. The main difference between the SMF and traditional multicast routing is that no multicast tree is built and maintained, and no group membership management is needed. Therefore all the nodes in MANET receive the multicast information. However, a multicast border gateway is required in a MANET to interoperate with other multicast routing protocols in the wired domain as SMF does not make use of traditional multicast method. We propose a MANET SMF gateway implementation solution that addresses the issues encountered within the gateway configuration, such as interaction with the Protocol Independent Multicast Protocol (PIM [4]). We will present the results of a tested single-gateway MANET implementation, and will also introduce a proposal for the multiple-gateway scenario.

In the IETF MANET working group, the SMF design group also presents proposals for handling multiple gateways [5]; they recommend to apply a to the multicast traffic when multiple gateways are injecting a flow into a MANET area. However this approach implies that equal multicast packets disseminated into the MANET by different gateways have different taggerID, and hence these packets cannot be detected as duplicates. Our approach differs by preferring the use of hashing by the gateways for marking equal packets injected into the MANET, hence making these equal packets compliant for duplicate detection.

This article demonstrates a successful implementation of the gateway functionality and extends its analysis by proposing a solution for the multiple-gateway configuration.

Cooperative blue-force tracking (BFT) and shared situation awareness (SA) in complex terrains

According to studies of network enabled capabilities, improved cooperative blue-force tracking (BFT)combined with timely shared situation awareness (SA) in complex terrains would increase mission effectiveness especially when and where participant coordination and synchronization are most critical. At the same time, such timely, pervasive and persistent SA offers the opportunity to decrease undesired collateral damage and fratricide by supporting the more desired and lasting effects. This paper reports on adaptive networks for mobile (mounted or dismounted participants) and stationary (fixed) units, that include networked sensors. These networks are extended to cooperatively build up a map of the relative location of all communicating and sensing units. Two possibilities for computing the estimated geolocation of each unit are explored where radio pseudoranges, Global Positioning System (GPS) and inertial measures are combined in order to obtain and maintain accurate geolocation in adverse conditions such as during GPS denial. The first option computes the relative positions and passes the results to the navigation component of each unit. The second option consists of sending the estimated distances between the units to a navigation component and then develops a geolocation map of all units. The paper also addresses the users' exploitation of the improved network to share information that contributes to better SA and maintain its currency by using dead reckoning (DR) position prediction to reduce the rate of position report updates while maintaining the desired accuracy and currency of shared information.

Creating cost effectively a dynamic picture of network participant geospatial information in complex terrains

Strategic, operational and tactical information, combat identification and blue-force-tracking provided by advanced "Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance" distributed system-of-systems improve the quality of decision-makers' situation awareness (SA). Such SA improvements increase the pace at which decision making can be done while maintaining a low risk of errors by decreasing the friction (the fog of war) in today's complex geopolitical contexts often conducted in urbanized areas. The first challenge addressed by this paper relates to generating accurate geolocation of agents even where satellite-positioning systems, such as the Global Positioning System, are unreliable or denied. The second challenge concerns the efficient sharing of this information for mobile agents in complex terrains by using advanced mobile ad-hoc network (MANET) technologies. The last challenge addressed consists in devising a set of rules based on a dead-reckoning error model for controlling the positional data updates shared over the MANET.

Self-aware/Situation Aware - Integrated Handhelds for Dispersed Civilian and Military Urban Operations

Successful response to fast-moving, life-critical situations - military combat, fires, disaster relief - usually depends on robust positioning capabilities and effective communications to provide commanders with comprehensive awareness of dynamic situations. Moreover, the systems providing this situation awareness need to be integrated and compatible with urban operations, and, suitably automated. This article describes design of portable handheld equipment integrating GPS and other location technologies with "self-aware" radio networks that can automatically identify and locate all the members of a unit involved in such missions.

SASNet Charter Document

The Land Force Army of Tomorrow Force Employment Concept (AoT FEC) describes an operational environment that will be less contiguous while continuing to be highly lethal. Further, the AoT FEC defines the need for land forces capable of adaptive and dispersed operations in complex environments across the full operational spectrum. As a result, sensing is becoming increasingly complex.

To meet the needs of contemporary operations, the CF, and specifically land based operations, require ground based sensors that can perform surveillance tasks to detect, classify and localize hostile forces 24-hours a day in all weather conditions, that can integrate within the emerging network operating environment, and can present a fused "sense picture" to tactically deployed forces. These sensors must enhance the surveillance capabilities of tactical commander defined critical terrain and objectives to support both the force protection function and contribute to the situation awareness required to plan and execute tactical land operations. As such, key components of the sensor system must include the reduction of the operators' workload while also providing greater situation awareness and greater persistence, thereby freeing troops for other tasks.

The SASNet TDP proposes to meet these requirements through the development of an easily deployable/recoverable self-healing network of distributed, self-configurable, taskable and manageable wireless sensors. The concept is to employ large numbers of different types of basic, inexpensive, expendable sensors (e.g. acoustic, seismic, passive infrared and magnetic) that form a network to cue more complex, expensive sensors including electro-optical imaging devices, thereby providing the tactical user with access to a wide range of complementary sensor data. As each sensor type has its own capabilities and limitations, such as the limited range found in passive infrared and magnetic sensors compared to the longer-range capability of acoustic and seismic sensors, when deployed in an ad hoc fashion they collaborate to provide more accurate, reliable, situational awareness data. SASNet will include autonomous sensor cross-cueing and data fusion capabilities in order to provide the operator with collated situational awareness information extracted from the sensor data. Integration of dismounted soldiers as part of the SASNet will also be examined.

As a component of a layered land force SENSE capability, the SASNet would be utilized to complement military Line Of Sight (LOS) surveillance and to provide continuous monitoring of gaps between sub-units, approaches, routes and key terrain within the Area of Operation (AO) which are not directly viewed or which may be utilized by an adversary during periods of reduced visibility. Using SASNet, tactical commanders will be able to obtain information on movements in areas of influence well ahead of the forward line of troops (FLOT). SASNet can be tailored to cover various types of areas, to monitor for example, from withdrawal routes, small area of unobserved approach, to larger and more complex perimeters. On Peace Support Operation (PSO), SASNet will be used to improve the ability to monitor cease-fire zones and no-go areas at great savings in manpower.
The SASNet TDP will demonstrate how a networked sensor system could be easily deployed, operated, and managed to enhance the effectiveness of deployed individuals, small teams and sub-units, while concurrently collecting relevant, accurate, situational awareness information as part of the deployed sensor web.

Multicast Forwarding Using Multiple Gateways and Hash for Duplicate Packet Detection in a Tactical MANET

Simplified Multicast Forwarding (SMF) [3] provides an optimized flooding mechanism in MANET environments to efficiently propagate multicast packets. In order to be more useful in a broader range of scenarios, we need to be able to get multicast packets to and from fixed infrastructures. Gateways in MANETs are more complex than regular MANET nodes as they require both to join multicast groups on behalf of the MANET, as well as to forward multicast packets between networks. Multicast gateways are required to interoperate with other multicast routing protocols in the wired domain. In this paper we show that by using a hash function we are able to assign packets with a common unique packet identifier that is further used for duplicate packet detection. Using the hash function in conjunction with multiple gateways, we lower the traffic overhead, increase the packet delivery ratio, and make the protocol more resilient to network partitioning as well as independent to the number of gateways.

GPS-INS-Radio and GIS Integration into Handheld Computers for Dispersed Civilian and Military Urban Operations

The proposed integration concept extends and insures quality geolocation and information sharing in a dynamic environment where the Global Positioning System (GPS) and communications are often denied to key players involved in critical operations. Such integration relies on robust sources of information such as inertial measures, maps and dynamic network topology. The geolocation and the adaptive network domains inform each other in order to increase their respective performance in terms of speed, accuracy, knowledge and shared awareness. Consequently, the envisaged transceiving handheld computer equipment offers unmatchable situation awareness, in-formation-sharing and network-management opportunities that could significantly improve mission effectiveness and success rate of complex operations especially under disperse civilian and military urban theatre conditions.

In this concept, the proposed equipment is self-aware be-cause it uses, exploits and memorizes information from diverse dependent and independent measures and sources. Then the networked system informs all participating agents and builds a distributed database that increases individual self-awareness and makes shared-awareness a robust reality. In contrast, analyses of joint operations-those among agencies of a country-and coalition operations-those among countries-have shown that although data are often available somewhere within the systems at play, the critical data are not necessarily shared appropriately and are often not transformed into end-users' knowledge. Exploiting the synergy between self-aware radios, geographic information and navigation systems, and command and control (C2) essential functions, offers participating agents a more effective transformation of the available data into knowledge. At the same time, sharing a common view of such information and providing communications allow developing in real time an evolving common intent and provide the essential landmarks for the synchronization, if not self-synchronization, of actions and tasks of a mission with a lower risk of undesired effects. For emergency operations, this means an increase in timeliness and effectiveness that would translate directly into saved lives.

The potential number of users and agencies for such technology integration justifies its exploration, its design and assessment for operations ranging from military routine to disaster relief. The impact on mission effectiveness of integrating positional with geospacial information and other operational information in joint and coalition operations has shown sufficient increase in mission success rate for justifying such technological and cultural changes. For disaster relief, reconstruction, major event, stability, urban, or standing contingency forces operations, proper technology integration, training and planning would improve operations success and tempo, save lives, reduce fratricide and ensure minimal collateral damage.

Cooperative Node Localization for Tactical Wireless Sensor Network.

This paper investigates a cooperative node localization scheme for a tactical WSN (Wireless Sensor Network) that delivers accurate location estimates using a minimum number of anchor nodes. An efficient non-linear data dimension reduction technique, the Curvilinear Component Analysis (CCA), is applied, adopting a distributed map generation algorithm to create the node locations. The proposed new approach using CCA is compared with another highly effective cooperative map scheme which employs the MDS (Multi-Dimensional Scaling) non-linear reduction method, demonstrating improved position estimate accuracy and efficiency. The strength and weakness of the two schemes are analyzed through extensive simulation experiments using tactical WSN deployment scenarios.

Localization Applying an Efficient Neural Network Mapping

Node location information is essential for many applications in Autonomic Computing. This paper presents and evaluates a new cooperative node localization scheme. We apply an efficient non-linear data mapping technique, the Curvilinear Component Analysis (CCA), to produce accurate node position estimates employing only a small number of anchor nodes. Being a light-weight neural network, CCA has the learning ability to self-organize maps of nodes, and to project node coordinates with improved accuracy and efficiency. We present the distributed CCA-MAP scheme that derives node locations in either range-based or range-free scenarios. Unlike other schemes, no further refinement is needed to improve the position estimates generated by the devised CCA projection method. Through extensive simulation studies, we evaluate the performance of our scheme for both regular and irregular networks of different configurations. Comparisons with other related localization schemes are also presented, demonstrating the improved location estimate accuracy and performance efficiency.

Autoconfiguration and Mobility Support .

This document describes approaches for auto-configuration and mobility support and shows how the RUNES networking architecture operates. We analyze use cases for addressing and routing, and identified that all unicast, broadcast and multicast routing solutions are necessary. For address auto configuration we investigate three approaches one for IPv4, another for IPv6 and a third, called SAMSON that could be used for IPv4 and IPv6 and other address structures. We investigate gateway detection for IPv4 and IPv6 networks, as well. In IPv6 hosts discover gateways via a router sending a Router Advertisement (RA) message to the host's subnetwork, and since the DHCP approach in IPv4 is too static, we propose to use a similar RA based solution in IPv4. We discuss gateway mobility from a practical view point and illustrate message flows and interfaces and design system architecture for concrete scenarios. For localization and tracking we investigate the particle filter based approach, which is providing location and time context in real-time with low error bounds so that it can be used in a variety of ubiquitous computing applications. Finally, we also describe how network merging and partitioning works in the SAMSON approach.

2006

Interoperable Networks for Secure Communications Task 3 (Mobility) Final Report

The INSC Mobility Task Area, Task 3 (T3), was responsible for investigating technical solutions that support improved network mobility within a future coalition network architecture. Additional T3 technical goals included examining evolving open standard Internet Protocol (IP) based solutions to better support interoperability and heterogeneity, investigating both IPv4 and IPv6 mobility enhancements, and analyzing technical issues relating to military adaptation of evolving open standard protocols. T3 focused its main efforts on the examination of related open standard network protocols and not on the particular wireless technologies that these protocols may eventually run on top of. This executive summary provides a brief overview of the various mobility technologies investigated by Task 3 and summarizes results and recommendations from our coalition experimentation. For additional background on technology issues, please refer to additional documentation contained in the Task 3 Mobile Networking Technology Assessment and Considerations Document.

Networking Infrastructures and Protocols

This document investigates numerous solutions, which will help creating an efficient network architecture within the scope of the RUNES IST project. We hereby introduce a network architecture with special consideration to the road tunnel scenario, which involves monitoring various physical parameters of the tunnel and guiding rescue personnel and passengers in case of emergency. Based on the recent progress on both sensor and ad-hoc network research and development, we can argue that future networked embedded systems will consist of a combination of sensor and traditional wireless ad-hoc works. This fact leads to network environments that are heterogeneous and at least two-tiered in terms of their communication capabilities. Future networked embedded systems will utilize both low power/capability sensor nodes and high power/capability nodes. For this reason, our architecture covers both sensor nodes, sensor routing nodes and multi-radio sensor routing nodes, including gateways to corporate and public networks. We analyse several solutions for addressing and naming, routing, localization, ad hoc and sensor network interworking, auto-configuration, security and Delay Tolerant Networking (DTN). As far as node addressing is concerned, we first looked at the work that was done by the EU 6th Framework Project Ambient Networks, where an addressing structure is specified in a layered fashion. Some of the existing routing protocols under consideration for our architecture are Directed Diffusion, Geographical and Energy Aware Routing (GEAR), Ad-hoc On Demand Distance Vector (AODV), Low-Energy Adaptive Clustering Hierarchy (LEACH), Two-Tiered Data Dissemination (TTDD), Location based multicast (LBM), GeoGRID and Temporally Ordered Routing Algorithm (GeoTORA). We identified two aspects of the node localization issue: the first one involves localizing the static sensor nodes, while the second involves localizing the mobile agent nodes. We analysed various autoconfiguration approaches; however, further investigation, development, and testing work is necessary to prepare RUNES networks for autoconfiguration. We also discuss network security issues related to the networks and scenarios that we plan to deploy within RUNES. The purpose of our Delay Tolerant Networking work is to implement a message replication protocol that minimizes as possible the number of replicas needed to be created and disseminated in the network; still guaranteeing a satisfactory delivery probability of the messages to their destinations. Finally, this document lists future research directions that we plan to undertake within RUNES.

Findings on a Semantically-Based Intrusion Detection Approach for OLSR MANET Protocol

The Optimized Link State Routing (OLSR) protocol is a proactive Mobile Ad hoc Network (MANET) routing protocol. OLSR (v1 [1] or v2 [2]) were not designed with integrated security measures. Research provides inputs on how to secure the OLSR protocol against attacks from outside intruders. To address the protocol vulnerabilities, authentication and encryption techniques have been proposed. We will focus on the attacks coming from inside intruders, i.e. coming from nodes that were successfully authenticated as being part of the MANET.

In this paper we present a follow-up on an "Effective Intrusion Approach" [3] based on the OLSR protocol semantic-checking, a solution that was successfully used in our test bed to detect intruders. To test the detection of intruders, we developed an implementation of a typical replay attack where a node first records traffic at a given time, to replay it at later time. Such an attack can be used, for example, to give the impression of a stale network. The intruder has sufficient knowledge of the protocol to increase OLSR's message sequence number and TC's advertised neighbour sequence number values so that compromised messages will take precedence over legitimate network control messages, in respect to OLSR's duplicate checking algorithms. This results in good packets being dropped, and bad packets being forwarded.

We show how our implementation of the semantic-checking based on OLSR protocol is able to identify the intruder, and also how implausible links are detected. Once the intruder is identified, counter measures need to be applied. The implementation of those measures is the subject of our next research and is briefly presented.

Detecting Wormhole Attacks in Mobile Ad hoc Networks through Protocol Breaking and Packet Timing Analysis

We have implemented a fully-functional wormhole attack in an IPv6 802.1lb wireless Mobile Ad Hoc Network (MANET) test bed running a proactive routing protocol. Using customised analysis tools we study the traffic collected from the MANET at three different stages: i) regular operation, ii) with a "benign" wormhole joining distant parts of the network, and iii) under stress from wormhole attackers who control a link in the MANET and drop packets at random. Our focus is on detecting anomalous behaviour using timing analysis of routing traffic within the network. We first show how to identify intruders based on the protocol irregularities that their presence creates once they begin to drop traffic. More significantly, we go on to demonstrate that the mere existence of the wormhole itself can be identified, before the intruders begin the packet-dropping phase of the attack, by applying simple signal-processing techniques to the arrival times of the routing management traffic. This is done by relying on a property of proactive routing protocols- that the stations must exchange management information on a specified, periodic basis. This exchange creates identifiable traffic patterns and an intrinsic "valid station" fingerprint that can be used for intrusion detection.

A Comparative Study of Routing Strategies for Wireless Sensor Networks: Are MANET Protocols Good Fit?

The operation of sensor networks places special requirements on routing algorithms. These requirements stem from the unique nature of these networks. For example, the algorithm needs to be data-oriented and it should impose the smallest possible overhead on the resource-constrained nodes of the network. It has been long claimed that algorithms designed for mobile ad hoc networks (MANET) should not be considered for sensor networks for several reasons. Most important of these reasons is their heavy operation overhead. In this study, we examine this claim by comparing two of the sensor network specific algorithms, directed diffusion and TTDD, with two MANET algorithms, AODV and OLSR which belong to the reactive and proactive routing categories, respectively. We run experiments with realistic sensor network scenarios. We show that MANET protocols perform significantly better than their sensor-specific counterparts. Finally, we offer suggestions for future research based on the results of our study..

2005

Support of Multimedia SIP Applications in Mobile Ad hoc Networks: Service Discovery and Networking Architecture

Multimedia real-time session services, such as voice and videoconferences are highly desirable in many Mobile Ad Hoc Networks (MANET). This paper investigates network architecture options and evaluates their performance metrics for supporting session-based multimedia services in MANET, using the standard Session Initiation Protocol (SIP) proposed by the Internet Engineering Task Force (IETF). A novel service discovery mechanism is presented to discover SIP service locations and capabilities, enabling service self-configuration in the MANET. The service discovery mechanism applies crosslayer design between the application and the routing layers to achieve improved system and protocol efficiency. Two SIP MANET networking architectures, both with and without the proxy server, are evaluated. The presented performance results demonstrate the efficacy of the solution, and illustrate network design guidance for supporting SIP applications over MANET.

An Effective Intrusion Detection Approach for OLSR MANET Protocol

The Optimized Link State Routing (OLSR) protocol is a proactive Mobile Ad hoc Network (MANET) routing protocol. Security aspects have not been designed into the OLSR protocol and therefore make it vulnerable to various kinds of attacks. Recent research efforts have focused on providing authentication and encryption techniques to secure the OLSR protocol against attacks from outside intruders. A second line of defense is required to provide intrusion detection and response techniques in protecting the OLSR protocol against attacks from inside intruders.

In this paper, we describe security threats to the OLSR MANET routing protocol and present an intrusion detection solution based on protocol semantics checking. Our approach is based on semantic properties that are implied in the protocol definition and specify the correct OLSR routing update behavior. Conflict checking based on semantic properties is applied in every MANET node. Any abnormal protocol semantics will trigger an intrusion alarm. While we use OLSR as an example, we argue that the presented approach can be applied to any Multi-Point Relay (MPR) proactive MANET protocol.

Support Real-time Interactive Session Applications over A Tactical Mobile Ad Hoc Network

This paper presents the service support mechanism for a high capacity Tactical Mobile Ad hoc Network (TacMAN) that aims to offer reliable realtime session applications. Using the Internet Engineering Task Forces (IETF) stan-dard Session Initiation Protocol (SIP), TacMAN delivers integrated real-time multimedia session and data services over a distributed application platform. In TacMAN, SIP user agents are automatically discovered and configured applying an efficient service discovery mechanism that leverages on the cross-layer design between the applica-tion and the proactive routing layer. Such an auto-discovery capability extends to track the presence and loss of user agents in the network, enabling fast re-grouping and re-establishment of session communications in the dynamic ad hoc environment. The paper presents the ap-plication architecture of TacMAN and evaluates its per-formance characteristics, demonstrating the efficiency of the approach, and illustrating network design guidance for supporting SIP applications over the tactical MANET.

Hierarchical OLSR -- A Scalable Proactive Routing Protocol for Heterogeneous Ad Hoc Networks

The IETF’s mobile Ad Hoc networks (MANET) working group has designated the optimized link state routing (OLSR) as being one of four base routing protocols for use in ad hoc networks. Ad hoc routing protocols in general, including OLSR, do not scale well in heterogeneous networks, as they do not differentiate between the transmission capabilities of various member nodes, nor the channel access control scheme used by nodes when performing routing computations, even though many of the protocols support nodes having multiple interfaces. Under OLSR, for example, the control messages are sent to all interfaces, generating a very high overhead. In this paper, we propose optimizations to OLSR in order to limit the amount of control traffic generated and to make more efficient use of the higher capacity links found in heterogeneous wireless networks. Using OPNET simulations, we introduce a hierarchical mechanism to OLSR, and demonstrate that the Hierarchical OLSR (HOLSR) greatly reduces the required protocol overhead, which improves protocol scalability in large size heterogeneous networks. To our knowledge, this paper represents the first attempt made to address in-dept scalability issues of the OLSR protocol on heterogeneous wireless ad hoc networks.

HOLSR: A Hierarchical Proactive Routing Mechanism for Mobile Ad Hoc Networks

This article reviews the Hierarchical Optimized Link State Routing (HOLSR) mechanism for heterogeneous mobile ad hoc networks. In this work, a heterogeneous mobile ad hoc network is defined as a network of mobile nodes which are characterized by different communications capabilities, such as, multiple radio interfaces. The article focuses in the proposal of the HOLSR protocol. The HOLSR mechanism is derived from the OLSR protocol; however, unlike OLSR, the HOLSR protocol takes advantage of the different mobile nodes capabilities to reduce the routing control overhead in large heterogeneous ad hoc networks, thus improving the performance of the routing mechanism.

Implementation of an IEEE 802.11 Link Available Bandwidth Algorithm to allow Cross-Layering

With the popularity and wide adoption of IEEE 802.11 equipment, wireless networks are being used in an increasing number of applications. Wireless links brings new challenges to communications protocols since link quality is unpredictable. To cope with this problem, many recent research proposals have employed cross-layering design. Often, the MAC layer is assumed to provide link quality metrics. Existing IEEE 802.11 radios and drivers do not provide detailed link quality metrics, which restrained a lot of cross-layering work to simulation environment. In this paper, we propose an algorithm that measures and computes link quality metrics inside IEEE 802.11 MAC so that it provides detailed link quality information to other layers of the protocol stack. Among other things, we implemented an algorithm that provides the available bandwidth to each neighbor node in an ad hoc network. This could be used in a number of scenarios to achieve work in the area of cross-layer design in real test beds. Typically, such work has been constrained to simulation or emulation environments due to the lack of link quality metrics provided by IEEE 802.11 MAC drivers.

Index Terms— Cross-layer design, IEEE 802.11, Mobile Ad hoc Networks, Wireless LAN.

A Lightweight Service Discovery Mechanism for Mobile Ad hoc Pervasive Environment using Cross-Layer Design

An effective service discovery mechanism is essential for the pervasive computing environment. Often required in delivering the pervasive computing applications, mobile ad hoc communications bring challenges to the service discovery function due to the resource restraint and the topology dynamics incurred in the network. This paper presents a lightweight service discovery mechanism applying cross-layer design to reduce the infrastructure and protocol overhead, and to improve service accessibility.

Integrated with the network routing layer, the proposed mechanism automatically identifies and selects the proper service discovery model for the current network configuration. The solution also adapts to network expansion with enhanced scalability. Simulation studies of real-time service scenarios employing the proposed mechanism are presented, demonstrating the efficiency of the mechanism and the satisfactory service performance results.

2004

"Implementing a Fully Distributed Certificate Authority in an OLSR MANET"

OLSR (Optimal Link State Routing) is one of the four base routing protocols being considered for use with MANETs (Mobile Ad hoc Networks) by the IETF's MANET working group. OLSR belongs to the proactive class of routing protocols in which the connection setup delay is minimized at the expense of heavier control traffic load on the wireless channel. Existing IETF draft proposals on OLSR do not yet address security issues. Although a PKI (Public Key Infrastructure) based security is deemed more appropriate for MANETs including OLSR MANETs, care should be taken to ensure that such an infrastructure does not add to the already heavy control traffic load in OLSR and, as much as possible, the existing OLSR control packets are utilized to support such infrastructures as well.

In this paper we describe our approach in which a PKI is tightly coupled with an OLSR MANET at the network layer level and the OLSR control packets are leveraged to support various security related activities as well. We have implemented a fully distributed CA (Certificate Authority) and integrated it with an existing implementation of OLSRv4 (OLSR for IP version 4). Intricate details of our implementation are presented to develop insight into key aspects of the proposed solution.

"Service Discovery for Support of Real-time Multimedia SIP Applications Over OLSR MANETs"

Support for real-time multimedia session services, such as real-time interactive voice-and-video-over-IP applications, is highly desirable in a mobile Ad Hoc Network (MANET). This paper presents a service discovery mechanism as an extension of the proactive OLSR (Optimized Link State Routing) protocol, enabling real-time interactive multimedia session applications using the Internet Engineering Task Force's (IETF) standard Session Initiation Protocol (SIP) in MANET. Effectively applying the cross-layer design between the networking and the application layer, a unified SIP service location distribution mechanism is proposed which can discover SIP service capabilities and server locations. Performance analysis and simulation results of the proposed scheme as applied to SIP MANETs running on OLSR are presented.

"Improving Scalability of Heterogeneous Wireless Networks with Hierarchical OLSR"

Ad hoc routing protocols in general, including OLSR, are not specifically designed for heterogeneous networks, and thus they do not efficiently exploit the higher-capacity links found in such networks, where nodes are equipped with diverse communications capabilities. Although these protocols support nodes with multiple interfaces, scalability problems may arise when the protocols are applied to heterogeneous networks. Under OLSR, for example, control messages are sent to all the interfaces, generating a very high overhead.

In this paper, we propose optimizations to OLSR in order to limit the amount of control traffic generated and to make more efficient use of the higher-capacity links in heterogeneous wireless networks such as military networks. Using OPNET simulations, we introduce a hierarchical mechanism to OLSR, and demonstrate that the Hierarchical OLSR (HOLSR) greatly reduces the required protocol overhead and thus improves protocol scalability in large size heterogeneous networks.

2003

"Integrating WLANs & MANETs to the IPv6 based Internet"

This paper presents a novel approach to integrate Wireless Local Area Networks (WLANs) and Mobile Ad-hoc Networks (MANETs) to the Internet Protocol version 6 (IPv6) based Internet. In the proposed network architecture, the mobiles, connected as a MANET, employ the Optimized Link State Routing (OLSR) protocol for routing within the MANET. Gateways are used to connect MANETs to the Internet. This paper extends the functionality of OLSR to support Mobile IP (MIP). This functionality is essential in a scenario where a node moving into an OLSR MANET needs to auto-configure its care-of-address and to propagate a Binding Update message containing its new care-of-address to its home agent and its correspondent node(s) located on the Internet. Automatic mode-detection and switching capability is also introduced in each mobile node to facilitate handoffs between WLANs and MANETs. Mobility management across WLANs and MANETs is achieved through Mobile IPv6 (MIPv6).

A real test-bed is constructed to demonstrate the viability of the proposed approach. Results from a performance evaluation on this test-bed are presented. Efficiency of handoffs between WLANs and MANETs is measured in terms of delay and packet loss. The impact of OLSR based route discovery and packet propagation, and Mobile IPv6 features such as movement detection and address auto-configuration on the handoff latency and packet loss are quantified. These performance benchmarks and metrics provide an assessment of the impact of the aforementioned system features on the QoS parameters associated with handoffs.

This is, to our knowledge, the first proposal to exploit the salient features of MIPv6 as well as OLSR in a collective fashion.

"Quality of Service Mechanism for MANET using Linux"

This paper describes a QoS mechanism suitable for Mobile Ad Hoc Networks (MANET). Routing and Quality of Service domain (Task 5 group) of Interoperable Networks for Secure Communications (INSC) has chosen the Differentiated Services (DiffServ) to be the base mechanism for flow classification in all INSC coalition networks. For the multimedia services (voice and video), several different service classification mappings are proposed by INSC to investigate. In this paper, the most suitable classification and scheduling algorithm for the voice and video in the MANET is presented.

A real IPv6 test-bed is constructed to demonstrate the viability of the proposed approach. In the test-bed the mobile nodes employ the Optimized Link State Routing (OLSR) protocol for routing within the MANET using Linux routers. Results from a performance evaluation on this test-bed are presented.

"Quality of Service routing in ad-hoc networks using OLSR"

In an ad-hoc network, all communication is done over wireless media, without the help of wired base stations. While many routing protocols have been developed to find and maintain routes based on a best-effort service model, quality-of-service (QoS) routing in an ad-hoc network is difficult because the network topology may change constantly and the available state information for routing is inherently imprecise.

In this paper, we discuss how to support QoS routing in OLSR (Optimized Link State Routing Protocol, one of the routing protocols under study by the IETF MANET Working Group). We develop heuristics that allow OLSR to find the maximum bandwidth path, show through simulation that these heuristics do improve OLSR in the static network case, and finally, we prove that for our ad-hoc network model, two of the heuristics are indeed optimal (i.e., guarantee that the highest bandwidth path between any two nodes is found).

"Proactive QoS Routing in Ad-Hoc Networks"

In this paper, we analyze the advantages and disadvantages of the proactive QoS routing in ad-hoc networks. We discuss how to support bandwidth QoS routing in OLSR (Optimized Link State Protocol), a best-effort proactive MANET routing protocol. Using OPNET, we simulate the algorithm, exploring both traditional routing protocol performance metrics and QoS-specific metrics. Our analysis of the simulation results shows that the additional message overhead generated by the proactive QoS routing have a negative impact on the performance of the routing protocol. Given the negative results, we identified research areas that would be worthwhile investigating in order to obtain better performance results.

2002

"MANET Global Connectivity and Mobility Management Using HMIPv6 and OLSR", Master Thesis, School of Computer Science

To achieve the seamless mobility for Internet mobile users who roam between Mobile Ad-hoc Networks (MANETs) and other parts of the Internet, one must consider a mechanism for efficient mobility management and handoff support in such an environment. This thesis presents a novel scheme to integrate MANETs with the Internet and support mobility across Wireless Local Area Networks (WLANs) and MANETs. The mobiles, connected as a MANET, employ the Optimized Link State Routing (OLSR) protocol for routing within the MANET. Mobility management across WLANs and MANETs is achieved through the Hierarchical Mobile IPv6 (HMIPv6) protocol. To the best of our knowledge, this is the first proposal to exploit the salient features of HMIPv6 in such a hybrid network architecture integrating MANETs with the Internet.

An implementation of the OLSR with HMIPv6 scheme is also presented in this thesis, which extends the OLSR protocol and ICMP6 protocol to support the cooperation of OLSR and HMIPv6.

Another contribution of this thesis is a performance evaluation on a HMIPv6 based test-bed composed of WLANs and MANETs. A set of performance benchmarks and metrics is exploited to quantify the impact of various factors of OLSR and HMIPv6 on the handoff latency and packet loss. Furthermore, the efficiency gain obtained from using HMIPv6 in such a hybrid network is investigated. The investigation result shows that the use of HMIPv6 can achieve up to 27% gain on reducing the handoff latency when a mobile roams within a domain. Concerning the reduction of the signaling load on the Internet, the use of HMIPv6 can achieve at least a 54% gain and converges to 69%.

"An IPv6 and OLSR based Architecture for Integrating WLANs & MANETs to the Internet"

This paper presents the results from a performance evaluation on a Mobile IPv6 based test-bed composed of WLANs (Wireless Local Area Networks), MANETs (Mobile Ad-hoc Networks) and the Internet. Location management and handoff efficiency is measured in terms of session setup delay and handoff delay. The mobiles, connected as a MANET, employ the OLSR (Optimized Link State Routing) protocol for routing within the MANET. Location management across WLANs and MANETs is achieved through Mobile IPv6. The impact of OLSR based route discovery and packet propagation, and IPv6 features such as neighbor discovery and address auto-configuration on the session set up latency, handoff latency and packet loss are quantified.

There are two main contributions reported in this paper. First, a novel approach is proposed to integrate MANETs into the Internet using Mobile IPv6 and OLSR. Secondly, various performance benchmarks and metrics are presented that are obtained using the test-bed developed jointly by CRC, Ottawa and NewMIC, Vancouver. These benchmarks are essential for assessing the impact of the system features listed above.