Mobile Ad-Hoc and Sensor Networks

Tremendous advances in embedded systems, sensors and wireless communications technology have made it possible to build large-scale wireless sensor networks (WSNs). Due to their potential applications,WSNs have attracted significant attention in the industry, academic, and government organizations. In particular, by commanding a large number of distributed and coordinated sensor nodes, WSNs can effectively act as the human-physical world interface in future digital world through sensing and actuating. However, the inherent characteristics of WSNs typified by extremely scarce resources (e.g., bandwidth, CPU, memory and battery power), high degree of uncertainty, and lack of centralized control pose significant challenges in providing the desired quality, information assurance, reliability, and security. This is particularly important for mission critical applications that involve information intensive WSNs including video sensors. In this talk, we will examine the uncertainty-driven unique challenges and key research problems in information intensive wireless sensor networks in the areas of aggregation, clustering, routing, data dissemination, coverage and connectivity, and security. We will present our novel solutions to some of these problems and conclude with future directions.

The recent researches in wireless networks prompt the opportunistic transmission that exploiting channel fluctuations to improve the overall system performance. In wireless ad hoc networks, nodes may have packets destined to multiple neighboring nodes. We consider an opportunistic scheduling that takes advantage of time-varying channel among different receivers to improve system performance. Maximizing overall throughput and satisfying QoS requirements for transmission flows are two important objectives that need to be considered. In literature, many opportunistic scheduling policies for ad hoc networks have been proposed, in which each transmitter schedules the transmission indepen-dently. However, due to co-channel interference, the decisions of neighboring transmitters are highly correlated. Moreover, to achieve the QoS requirements, nodes have to be cooperative to share the common wireless channel. In this paper, we formulate the opportunistic scheduling problem taking the interaction among the neighboring transmitters into account. We present an optimal scheduling policy which maximizes the overall network performance while satisfying QoS requirements of individual flows. We also proposed COS, a distributed Cooperative and Opportunistic Scheduling algorithm, which modifies IEEE 802.11 protocol to implement the optimal scheduling policy by exchanging average channel conditions and QoS factors among 2-hop neighboring nodes. Simulation results indicate that our implementation achieves higher network throughput and provides better QoS support than existing work.

Consider a wireless ad hoc network with random access channel. We present a model that takes into account topology, routing, random access in MAC layer (governed by IEEE 802.11orslotted aloha) and forwarding probability. In this paper , we are focusing to study the effect of cooperation on the stability and throughput of ad-hoc network. Forwarding packets of other nodes is an example of activity that requires such a collaboration. Hence, it may not be in interest of a node to always forward the requesting packet. We propose a new approach (based on

cycle of transmissions

) to derive throughput of multi-hop routes and stability of forwarding queues. With this cycle approach, we correct the analytical expressions derived in [2] and discover that their results are valid only in particular cases such as symmetric networks. However, in this paper, we get extended results for general network case. Moreover, we confirm that (i) the forwarding queues in a system of weighted fair queues has a special property and (ii) the end to end throughput of a connection does not depend on the load of the intermediate forwarding queues between a source and a destination. We perform extensive simulations and verify that the analytical results exactly match the results obtained from simulations.

The paper addresses mobility control routing in robotic sensor wireless networks, where either mobile sensors or mobile actuators assist in wireless data intensive transmissions from sensors. Given a communication request between a source destination pair, the problem is to find a route and move each node on the route to its desired location, such that total transmission power is minimized. We study the optimal number of hops and optimal distance of adjacent nodes on the route. We propose OHCR algorithm that is based on the optimal number of hops on the route. We further propose MPoPR algorithm that minimizes transmission power over progress. After finding an initial path, strategies of move in rounds and move directly are both considered to move nodes to desirable locations. Extensive simulations are conducted to evaluate our proposed routing algorithms.

Multicast for ad hoc networks becomes popular. However, along with increase of the network size and node mobility, it is difficult to design the multicast routing for large ad hoc networks with high mobility. In order to cope with this difficulty, this paper proposes a new hierarchical multicast routing for such ad hoc networks. The characteristics of the proposed scheme are introduction of the inter-cluster group mesh in the autonomous clustering. The states of clusters are changed according to join and leave of multicast members and the group mesh among clusters is dynamically constructed. The simulation results show that the proposed scheme is scalable for the network size and adaptable to node mobility.

Directed diffusion (DD) is a data-centric routing protocol based on purely local interactions between individual network nodes. This protocol uses application-specific context for data aggregation and dissemination. Therefore, it can be completely matched to the application requirements in a large distributed sensor network. Many work have been recently done to improve the energy efficiency of this protocol. In this paper, an extension to DD is presented in order to construct multiple paths between the sink and the sensor sources. Using this method, load-balancing is implemented to increase the life-time of the sensor nodes collaborating in the routing process. The proposed protocol, Multi-path directed diffusion (MDD), can produce more than one disjoint or braided paths and spread the data collected in the sources, properly between the paths. In this way, an efficient load balancing mechanism has been implemented. The simulation results show that through using MDD, the lifetime of the network connections between the sources and the sink will be increased and the interest flooding rate which is proved to be an expensive operation can be reduced.

In this paper, we are interested in simple routing protocols, for wireless sensor networks. One of the major challenging issue in sensor networks is that nodes rely on batteries with limited capacity. Therefore, to extend the life of the sensors and the reliability of the network, an efficient routing algorithm can reduce/optimize energy consumption by reducing routing overhead while maintaining a high delivery rate. Moreover, a good routing method should compute a routing path that is as close as possible to the shortest path. We propose

ORouting

, a localized energy efficient greedy routing scheme. To minimize the gap between the shortest path and the computed path, ORouting computes its routing path by locally selecting the next hop node based on its orthogonal distance to the direction of the source/destination pair. Moreover, in its routing decision, ORouting is biased towards its neighbors in the forward direction towards the destination. We compare ORouting to several routing protocols. We show, through simulation, that our protocol improves significantly energy consumption and achieves a high percentage of successful routings.

Gossiping is a lightweight and simple technique for information dissemination in many application domains, be it in Wireless Sensor Networks (WSNs), Mobile Ad-hoc Networks (MANETs), or Vehicular Ad-hoc Networks (VANETs). Much research has been conducted in the past on probabilistic dissemination methods because of their efficiency compared with simple flooding and their simple application. However most work was focused on static gossiping, i.e., the gossiping probability cannot be adapted according to topology changes. Thus, topology characteristics have to be known in advance.

In this work the use of position information for building up a neighborhood relationship is proposed. Based on this information, a forwarding hierarchy is constructed and the protocol is capable to adjust the dissemination probability dynamically in a distributed manner. The protocol is evaluated in a highway scenario, where the network characteristic varies from sparse networks with highly mobile nodes to a traffic jam with very high node density and low node velocities. The applicability of the proposed protocol for such scenarios is shown by simulations.

To balance energy consumption for nodes is an important factor considered in wireless sensor networks (WSN). In the paper, we research a heterogeneous wireless sensor networks with two different type sensors which have different initial energy as well as have different length data message to transmit. Each sensor node in such a network is systematically gathering and transmission sensed data to a base station for further processing. We develop and analyze the protocol based on residual energy and energy consumption rate (REECR), which is an energy efficient routing protocol we proposed previously for heterogeneous wireless sensor networks. Although REECR protocol is more energy efficient than Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol, it is not very ideal to balance the energy consumption of nodes, namely, from the first node dies to the last node dies, the time span is long. This paper proposed a zone-based REECR (ZREECR) routing protocol to balance the energy consumption of nodes in the networks, simulation results show that all nodes die from start to end become shorter, the balance of energy consumption between nodes is improved.

To alleviate the problem of sub-optimal routing and multiple encapsulations in nested mobile network, a hierarchical based route optimization scheme (HBRO) is proposed. Root mobile router (MR) works as mobility anchor point (MAP) and transmits packets for the mobile network nodes (MNNs). Following advantages can be achieved with this scheme: 1) correspondent node (CN) transmits packet directly to MAP, bypassing all of the home agents (HA) of MRs; 2) tunnel exists only inside the mobile network. We build an analysis model for for performance evaluation, and the analysis results indicate that packet delivery overhead decreases significantly, and the delivery efficiency is beyond 80 percent when packet size is larger than 200 bytes and network resources are utilized to a great extent.

Within Ad hoc networks, IP connectivity is achieved with the help of multi-hop routing; nodes are supposed to cooperate and act as routers for the benefit of the others. However, this cooperation-based paradigm has limitations, because nodes do not always make their resources available, properly. We propose a reputation-based routing protocol, called MOOR, for application to hybrid Ad hoc networks. MOOR aims at improving the reliability of communications between Ad hoc nodes and the gateway to an infrastructure-based network. We present an application–motivated performance analysis of our protocol MOOR, which allows to quantify the benefit in terms of radio network coverage increase. The impact of non-cooperative nodes on a MOOR protected network remains rather low, even for nodes located 5 hops away from the gateway.

To achieve high protocol efficiency is one of the primary goals in designing routing protocols for mobile ad hoc networks (MANETs), because high protocol efficiency implies low additional control overhead and power cost, which are two key issues in MANETs due to the inherited bandwidth and power-constrained characteristic. In this paper, an AODV improvement protocol with the Hello message mechanism is presented based on wireless link availability prediction. The simulation results demonstrate that the improved AODV improves the performance in terms of latency and protocol efficiency greatly, compared to the standard AODV with the periodic Hello message broadcast mechanism.

This paper investigates the sink positioning problem in Wireless Sensor Networks(WSNs) with the consideration of the energy-latency trade-offs. Energy-efficiency and low-latency are two major objectives in most researches on WSNs. Positioning the sink properly and exploiting its mobility can improve the two performances. A novel linear programming model is proposed to solve the sink positioning problem. Its objective function represents the overall performance of the network lifespan and the average packet latency. We can get not only the position pattern of the sink but also the sojourn time ratio for each possible position according to the optimization results. Simulations are accomplished on NS-2. The results show that compared with a static sink approach or a positioning approach which only concerns the energy-efficiency, our approach can greatly shorten the average packet latency and prolong the network lifespan, especially when the sensor nodes are distributed asymmetrically or the traffic load is unbalanced.

There are many applications of large scale sensor networks in which both the stimulus and the data collection stations are mobile (i.e. animal tracking, battlefield chasing). TTDD is a scalable and energy-efficient data dissemination model designed for this type of scenarios. However, TTDD only focused on handling mobile sinks. In this paper, we extend TTDD to deal with both mobile sources and sinks and evaluate the effectiveness of two potential extended TTDD schemes. Simulation results are presented to compare their performance in terms of energy consumption, delay and success rate. It is shown that the two schemes have similar performance when the moving speeds of the phenomena objects are slow. However, when the phenomena objects moving exceed certain speed, the advantages of one scheme over the other become unneglectable.

Many routing protocols for wireless sensor networks based on location information have been proposed such as GPSR, LAR, IGF, etc. When these routing protocols are used with existing MAC protocols, however, the sleep and wake-up scheduling of many MAC protocols degrades the routing protocol performance because of the long latency for periodic scheduling and synchronization overhead. In this paper, a cross layered routing and MAC protocol, CBT(Cell Back-off Time) protocol, has been proposed for the enhancement of successful routing in the Wireless Sensor Network environment considering the mobility of sensor nodes. Analysis and Simulation shows that CBT shows good performance when network density is high and nodes have mobility.

In wireless sensor networks, it is necessary and important to send information to all nodes. In some situation, every node has its own data to send to all the other nodes. The communication patterns are all-to-all broadcasting, which is called data exchange problem. In this paper, we present an efficient data exchange protocol using improved star trees. We divide the sensor area into four equal grids and each sensor node associates itself with a virtual grid based on its location information. These grids can be divided again if necessary. In each grid, we calculate the position of root node with location information of sensor nodes. Then, an efficient data exchange Star-Tree was constructed and used to achieve the exchange behavior in the grid. The fused data of each grid was sent to the center node. Simulations show that our protocol can prolong the lifetime about 69% to the multiple-chain protocols, and the delay can be reduced at least 35%.

IEEE 802.11-based wireless local area networks (WLANs) have been set up in many public places in recent years. It provides convenient network connectivity to mobile nodes (MNs) and allows users moving from one wireless network to another. With mobility protocol support, such as Mobile IPv6 (MIPv6), people can roam across wireless IP subnets without loss of network-layer connectivity. However, the handover latency may make users uncomfortable in MIPv6. To support seamless handover, an enhanced MIPv6 scheme, Fast Handovers for Mobile IPv6 (FMIPv6) [1], was been proposed. In order to further reduce the handover latency, integration IEEE 802.11 and MIPv6 is necessary. Unfortunately, when integrating the IEEE 802.11-based standard with FMIPv6, FMIPv6 always fails to perform predictive handover procedure and results in reactive handover. It is because of the protocol nature of IEEE 802.11 and the weak relationship between IEEE 802.11 and FMIPv6. Furthermore, a MN can not receive packets destined to it as it sends the FBU to the original access router (OAR). This would cause unnecessary packet loss and make the predictive handover have more packet loss then reactive. Those issues will cause quality of services degradation and make real-time application unreachable. In this paper, a low-latency MIPv6 handover scheme will be proposed. It is a FMIPv6-based scheme, which is based on an active-scan scheme link layer assistance. It has the advantage of FMIPv6 and can reduce the unnecessary packet loss when the handover occurs. Also, with the active scheme assistance, it can avoid the longest phase that IEEE 802.11 will enter, and can lower the handover latency.

Fair allocation of bandwidth and maximization of channel utilization are two important issues when designing a contention-based wireless medium access control (MAC) protocol. However, fulfilling both design goals at the same time is very difficult. Considering the problem in the IEEE 802.11 wireless local area networks (WLANs), in this work we propose a method using a p-persistent enhanced DCF, called

P-IEEE 802.11 DCF

, to achieve the weighted fairness among multiple priority classes in a WLAN. The key idea of this method is that when the back-off timer of a node reaches zero, the transmission probability is properly controlled to reflect the relative weights among data traffic flows so as to maximize the aggregate throughput and to minimize the frame delay at the same time. In particular, we obtain the optimal transmission probability based on a theoretical analysis, and also provide an approximation to this probability. The derived optimal and approximation are all evaluated numerically and simulated with different scenarios. The results show that the proposed method can fulfill our design goals under different numbers of priority classes and different numbers of hosts.

In this paper, a dynamic hierarchical location management scheme for Host Identity Protocol called DH-HIP is proposed to support micro-mobility. DH-HIP has a three-layer architecture which is managed by Rendezvous Server (RVS), Gate RVS and Local RVS (LRVS) respectively. The host selects its LRVS and computes the optimal size of administrative domain according to its current mobility and packet arrival rate. Furthermore, an analytical model to study the performance of DH-HIP and HIP is presented. Analytical results show that the signaling cost is significantly reduced through DH-HIP compared with the IETF HIP scheme under various conditions.

Location-centric

data storage is a fundamental paradigm for data management in wireless ad-hoc networks. It guarantees that data is stored at network nodes near specific geometric reference locations in the region where the network is deployed. In mobile ad-hoc networks, maintaining spatial proximity between data and its associated location requires explicit migration mechanisms in order to “keep the data in place”. In this paper we propose comprehensive policies for data migration that effectively maintain the spatial coherence of data given the particular characteristics of mobile ad-hoc networks. Using extensive simulations we show how the proposed policies outperform related migration approaches over a wide range of system parameter settings, in particular, node density, network dynamics, and migratable data size.

This paper proposes EL-MAC, a contention-based medium access control (MAC) protocol, which is efficient and low-latency for the wireless sensor network (WSN). EL-MAC introduces duty-cycle and virtual cluster scheme within the framework of S-MAC to reduce energy consumption and to self-organize network. Besides, Inspired by D-MAC, the scheme of data forwarding chain (DFC) is proposed for reducing the latency in multi-hop transmission. The experiment of simulation shows that EL-MAC has lower latency and higher throughput with comparative energy consumption on different traffic load condition than S-MAC.

Power-efficiency and transmission delay are critical for periodical data gathering applications in wireless sensor networks. This paper presents a scalable power-efficient data gathering protocol with delay guaranty (PDGPDG) for wireless sensor networks. The protocol attempts to balance the energy consumption and transmission delay by dividing the entire network into clusters and then organizing clusters as sub-chains. The parallel transmission among different clusters minimizes the delay and routing data along near optimal sub-chain in the clusters reduces the total energy dissipation. PDGPDG is efficient in the ways that it prolongs the lifetime of network, as well as it takes much lower time to finish a transmission round. Simulation results show that it demonstrates about 200% better performance than that of LEACH in terms of network lifetime and improves the

energy

×

delay

metric by a factor of 2~6 compared to PEGASIS.

Data rate selection for IEEE 802.11-based wireless networks is not specified in the Specification. The problem of determining an appropriate data rate for the sender to send DATA frames and to adapt to changing channel conditions is referred to as

rate adaptation

. We propose DRA (differential rate adaptation), a rate adaptation scheme for IEEE 802.11 networks. It enables a high network throughput by adaptively tuning the data transmission rate according to the channel conditions. It is responsive to link quality changes and has little implementation overhead. Our experiments indicate that DRA yields a throughput improvement of about 20% to 25% compared to previous work.

Mobile multicast is a research hotspot and can provide many applications. Some schemes have been proposed to support the mobile subscriber, but most of them study the construction algorithm of dynamic multicast delivery structure and use the analysis and simulation to evaluate the performance, little concern on the multicast disruption time and protocol cost. In this paper, we propose a Multicast Listener Discovery (MLD) Proxy based Fast Multicast protocol for Mobile IPv6 (MP-FMIPv6), and implement simplified MLD proxy function on Home Agent (HA) and extend MLD host part function on MN. The analytical results show that MLD proxy based fast multicast can reduce multicast disruption time and cost. To evaluate the performance of proposed scheme in real applications, we setup a test-bed and compare it with Bi-directional Tunneling (BT) and Remote Subscription (RS) methods. The experiment results show that the proposed scheme nearly improves the multicast disruption time by 2.4 times and 3.66 times, and saves the cost about 19.1% and 57.4%, respectively.

This paper introduces a protocol for network-based localized mobility management solution, and develops an analytic model for the performance analysis based on one-dimensional random walk of mobile node. Based on the analytic models, the location update cost and the packet delivery cost are formulated. Then, the impacts of average cell residence time and the number of mobile nodes in a cell on the total cost are analyzed, respectively. In addition, the variation of the total cost is studied as the session-to-mobility ratio is changed and the optimal local mobility domain size to minimize the total cost is also investigated. The analysis results indicate that the session-to-mobility ratio and the local mobility domain size are critical performance factors in order to minimize the total cost.

Leading MAC protocols developed for duty-cycled WSNs such as B-MAC employ a long preamble and channel sampling. The long preamble introduces excess latency at each hop and results in excess energy consumption at non-target receivers in ultra low-duty cycled WSNs. In this paper we propose AS-MAC (Asynchronous Sensor MAC), a low power MAC protocol for wireless sensor networks (WSNs). AS-MAC solves these problems by employing a series of preload approach that retains the advantages of low power listening and independent channel sampling schedule. The preload massage includes a destination address and a remaining time until data transmission. Moreover AS-MAC offers an additional advantage such as flexible duty cycle as data rate varies. We demonstrate that AS-MAC is better performance than B-MAC through analysis and evaluation.

In wireless sensor networks (WSNs), congestion may occur when sensor nodes are densely distributed and/or burst a mass of data flows, the congestion tends to cause packet loss, which sequentially causes lower throughput and wastes energy. To address this challenge this paper proposes a new congestion control scheme, Phase-divided TCP (PTCP), for wireless sensor networks. It controls the congestion through phase-divided adjusting of the growth rate of the TCP window in the slow-start. Our simulation results demonstrate that the proposed scheme can dramatically resolve congestion control problem, and improve TCP performance of wireless sensor networks.

In this paper, we present a low latency media access control scheme which we call LLMAC (Low Latency MAC) for event-driven wireless sensor networks (WSN). In this kind of WSN, sensors do not regularly send data to the sink. They send a burst data only when there is an event in the monitoring area. It takes time for this burst data to arrive to the sink. Normally, these events are critical and we hope to obtain the information on the event in the shortest delay. Hence, the latency is considered to be a crucial requirement in event-driven WSN contrary to the traditional wireless networks where the fairness is the most important requirement. Our proposal LLMAC makes a trade-off between fairness and latency in order to offer a shorter latency transmission when certain events happen. The performance evaluation shows that our proposal reduces the latency in comparison to existing MAC protocols.

Flooding in wireless ad hoc networks is a fundamental and critical operation in supporting various applications and protocols. However, the traditional flooding scheme generates excessive redundant packet retransmissions, causing contention, packet collisions and ultimately wasting precious limited bandwidth and energy. In this paper, we propose an efficient flooding protocol called

vertex forwarding

, which minimizes the flooding traffic by leveraging location information of 1-hop neighbor nodes. Our scheme works as if there were existing a hexagonal grid in the network field to guide the flooding procedure, only the vertex nodes which are located at or nearest to the vertices of the grid should be nominated to forward the message. We also provide a distributed algorithm for finding the vertex nodes. Simulation results show that our scheme is so efficient that it is almost able to reduce the number of forward nodes to the lower bound.

A typical scenarios was considered , in which an event, such as a mobile sink arriving to collect data via the wireless sensor network, initiates the collection of one packet of data from each node in the surrounding cluster. The node requesting the beacon synchronizes its time clock and purpose to the cluster and assumes the role of clusterhead. All nodes covers an area with a radius of several hundred meters, to within a few microseconds. We exploit this ability to extend the Contension Windows to improve retransmission algorithms in Zigbee MAC protocols. The result is a retransmission algorithm that uses a Extended Shared Contention Window (ESCW) that is easy to implement and results in fewer collisions than retransmission algorithms that use Binary-Exponential-Backoff (BEB). We show via numerical and simulation results that an ESCW-based Zigbee protocol performs significantly better – in terms of energy usage, throughput, and the time to complete the data collection task – than standard Zigbee (IEEE802.15.4).

Multi-hop wireless networks provide a quick and easy way for networking when we need a temporary network or when cabling is difficult. The 802.11 Medium Access Control (MAC) plays an important role in the achievable system performance. There have been many studies on analytic modeling of single-hop 802.11 wireless networks but only a few on the analysis of multi-hop wireless networks. Furthermore, the object of these researches is an homogeneous ad-hoc wireless networks; therefore they are not appropriate for a network with structure such as wireless mesh networks. This paper introduces an analytic model of throughput performance for the IEEE 802.11 multi-hop networks, which allows us to compute the achievable throughput on a given path in multi-hop wireless networks. The model shows that there is an optimal point at which throughput is maximized. Using this model and a Markov model for modeling the operation of the IEEE 802.11 DCF we can determine the amount of data that each node should inject to the network to get the best throughput performance.

In large-scale wireless sensor networks, efficient service discovery and data transmission mechanisms are both essential and challenging. Ant colony algorithm which has been used to resolve routing, localization and object tracing issues in mobile ad hoc and sensor networks provide a valuable solution for this problem. In this paper, we describe a novel scalable Action-based Service Discovery Protocol (ASDP) using ant colony algorithm in wireless sensor networks. ADSP can abstract the semantics information from the data via the nodes or user operation and map them into six different action sets. Then it adjusts the related parameters to satisfy with service and transmission requirements from different kinds of actions. We evaluate it against other approaches to identify its merits and limitations. The simulation results show that ASDP can maximize the network utilization. Farther experiments indicate it scales to large number of nodes.

In this paper, we propose a real time scheduling policy over 802.11 DCF protocol called Deadline Monotonic (DM). We evaluate the performance of this policy for a simple scenario where two stations with different deadlines contend for the channel. For this scenario a Markov chain based analytical model is proposed. From the mathematical model, we derive expressions of the saturation throughout and the average medium access delay called service time. Analytical results are validated by simulation results using the ns-2 network simulator.

With the network size growing, routing protocols of mobile ad-hoc networks (MANET) face many challenges. The most critical issue is the lack of bandwidth and computation capability. This paper describes the Parallel Link State Routing protocol (PLSR) that is suitable for MANET. The key concept used in the protocol is that of graph decomposition. This technique substantially raises the rate of routing updating; meanwhile it reduces the message overload as compared with a classical flooding mechanism and some other link state routing protocols. In PLSR, the network is a two-levels topology, and many problems caused by “flat” multi-hoppings will disappear. Thus, the second optimization is achieved by sub-network that reduces the control messages. As a third optimization, the routing computation will be in several sub-networks simultaneity. Hence, comparing with current link state algorithms, the routing table of PLSR will be regenerated quickly as the network topology changes.

It has been shown analytically [1],[2] that significant performance improvements as compared to existing technologies (e.g., IEEE 802.11) can be achieved in random access wireless networks. In [3] we proposed a fully distributed channel access paradigm based on the opportunistic communication principal called the Channel MAC paradigm suitable for distributed wireless networks such as ad hoc networks. In this paper, we analytically derive the throughput of the Channel MAC. It provides a throughput-limit on the channel-based MAC mechanism in shared multiple access environments without collisions or capturing effects. Both simulation and analytical results reveal possible performance improvement over existing techniques.

Traditional transmission control protocol reduces its performance by misinterpreting mobility losses due to node motion as congestion losses in wireless mobility network. While it has been shown that TCP Vegas provides better performance compared to TCP Reno, studies have identified various issues associated with the protocol in mobile ad hoc networks. This paper proposed adaptive congestion control scheme based on Traditional TCP. The key idea of our approach is to monitor permanently the TCP flow and record useful data to infer the current state of mobility ad hoc networks when packet losses are perceived, distinguish losses packets between bit error and congestion based on fuzzy logic theory, then based on wireless network link state, such as bit error, network congestion, or rerouting, Appropriate congestion control algorithm be choose to overcome limitations. Our experiments show that the scheme is able to avoid oscillation of TCP sender congestion window, and obtain more throughput than traditional transmission control protocol.

Recently, some proposals have suggested that maintaining the same contention window (CW), or reducing it, for nodes suffering packet losses, due to channel transmission impairments, is effective in increasing the performance of the IEEE 802.11 in noisy environment. Our study presented inhere will prove analytically and via simulations that this should not be necessarily the case. To facilitate our analysis, we consider two binary exponential backoff (BEB) algorithms in our study: a standard BEB where a host increases its CW upon every packet loss (collision or transmission error) and another access method with a capability to differentiate between the type of losses; here, a host experiencing a loss will increase its CW only after a collision and remain in the same backoff stage otherwise. We show that the second access procedure outperforms the standard BEB when the network is lightly loaded. However, in a congested network, this quick recovery property results in intensifying the collisions among contending nodes and hence yields a poor system performance. We propose a hybrid method that takes advantage of both access methods to achieve better throughput under various network loads.

The choice of transmit power determines the transmission range and carrier sensing range. Thus, the transmit power is a key to the tradeoff between the amount of spatial reuse and probability of collisions in wireless multi-hop ad hoc networks. In this paper, we propose a realistic analytical model to study the performance of the IEEE 802.11 access method in multi-hop wireless networks by incorporating the effect of transmit power and physical carrier sense. Using the model, we investigate the effect of these attributes on the throughput obtained by individual nodes. Our results show that performing power control and carrier sense threshold tuning using the two way handshake offer higher advantages and achieve better throughput than that achieved using the four-way handshake.

The access scheduling on the control channels in TDMA wireless mesh networks is studied in this paper. The problem is to assign time-slots for each node in the network to access the control channels so that it is guaranteed that each node can transmit a control packet to any one-hop neighbor in the scheduling cycle. The objective is to minimize the total number of different time-slots in the cycle. This paper has taken the large interference range problem into consideration and proposed two algorithms for the scheduling problem, namely, One Neighbor Per Cycle (ONPC) algorithm and All Neighbors Per Cycle (ANPC) algorithm. The number of time-slots by ANPC algorithm is upper-bounded by min(

n

, 4

K –

2) in some special cases, where

n

is the node numberand

K

is the maximum node degree. Both centralized and fully distributed versions are given. Simulation results also show that the performance of ONPC is rather better than ANPC.

This paper considers large-scale dense wireless sensor networks with path-constrained mobile sink. From the viewpoints of improving data equilibrium and energy-saving, we propose an enhanced energy efficient communication protocol in which a partition algorithm of overlapping time based on data equilibrium is designed to minimize the data variance and disequilibrium from each node. We present a data equilibrium information diffusion method to control the amount of collected data to avoid the waste of data and energy. Simulations under OMNET++ and MATLAB show that with protocol and algorithms proposed in this paper we can achieve better performance than other conventional methods in terms of data equilibrium rate, network lifetime and energy dissipation equilibrium rate.

We present a simple and efficient distributed method for determining the transmission power assignment that maximises the lifetime of a data-gathering wireless sensor network with stationary nodes and static power assignments. Our algorithm determines the transmission power level inducing the maximum-lifetime spanning subgraph of a network by means of a distributed breadth-first search for minmax-power communication paths, i.e. paths that connect a given reference node to each of the other nodes so that the maximum transmission power required on any link of the path is minimised. The performance of the resulting Maximum Lifetime Spanner (

MLS

) protocol is validated in a number of simulated networking scenarios. In particular, we study the performance of the protocol in terms of the number of required control messages, and compare it to the performance of a recently proposed Distributed Min-Max Tree (

DMMT

) algorithm. For all network scenarios we consider,

MLS

outperforms

DMMT

significantly. We also discuss bringing down the message complexity of our algorithm by initialising it with the Relative Neighbourhood Graph (RNG) of a transmission graph rather than the full graph, and present an efficient distributed method for reducing a given transmission graph to its

RNG

.

This paper presents an energy-efficient distributed target coverage algorithm(EDTC) for heterogeneous wireless sensor networks(HWSN) with multiple sensing units. In order to utilize the energy more efficiently, the sensor priority is introduced in this paper to integrate the sensing ability and the remaining energy together. EDTC is locally and simultaneously carried out at each sensor in a rounding fashion. Each sensor decides the on/off status of its sensing units at the beginning of each round, and then broadcasts the decision to its one-hop neighbors. The higher the priority of a sensor is, the shorter the decision time it needs. Simulation results show that compared with Energy First(EF) scheme and Integer Linear Programming(ILP) solution, EDTC has longer network lifetime than EF, and the performance difference between EDTC and ILP solution is confined within 10%.

Appling security to messages traveling over wireless links in sensor nodes requires additional energy. This paper describes our suggestions on balancing the level of security and energy consumption based on our measurements using CrossBow and Ember sensor nodes. It was found that the node microcontroller’s CPU operates for substantially longer times for both hashing and encryption operations compared to the time for handling messages without any security. However, this has little overall impact on energy consumption. The longer high-power radio transmission times due to hashing were especially costly. For the full operational mode, with CPU processing and also radio transmission of messages, our results indicate that the lifetime of a transmitting node in a security regime is only about one-half of the lifetime without security. Hence, we provided design guidelines to apply security with energy consideration for WSN. They include 2 to 8 bytes MACs for integrity and authentication instead of SHA-1, and the size of messages should match the steps of encryption algorithms.

In MANET, Node misbehavior due to selfish or malicious reasons can significantly degrade the performance of ad hoc networks. To cope with misbehavior in such self-organized networks, an incentive mechanism must be in place. In this study, a trust-based incentive model on a self-policing mechanism is proposed to make collaboration rational for selfish/malicious nodes. This trust system makes them evaluate the trust of their neighbor locally to mitigate contamination by direct observation and the use of second-hand information available. In our approach, every node maintains a trust rating about every node else they care about. Meanwhile, trust fading and redemption are brought about by update and re-establishment of the trust to show robustness. Performance by simulation reveals that in the case of existing malicious nodes, Dynamic Source Routing (DSR) with proposed trust-based node incentive mechanism performs better than DSR in terms of packet successful delivery ratio and mean number of packets dropped.

Apply the theory of vector quantization and LBG algorithm in the Information Theory and Data Compress,this paper present a one by one relationship between the cluster and cell,the cluster head and code vector,the node and vector,turn the process of clustering into the process of cell segmenting.Then design a new clustering algorithm aiming high stability in cluster structure and good performance in load balancing of cluster head.It has been proved that this algorithm has good performance in load balancing and the structure of the cluster has high stability after the simulation.

Cooperative transmission breaks away from traditional transmission which only has single transmitter and single receiver in wireless networks, which enable single antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenna transmitter in order to achieve transmit diversity. Space-time block coding (STBC) is an attractive transmission diversity technique because of its linear complexity. Furthermore, signal space diversity can increase the diversity order through interleaving over coordinates and choosing a proper signal constellation. In this paper, cooperative transmissions for wireless sensor networks are considered. In order to improve the system performance, a new cooperative transmission scheme without perfect synchronization using both signal space diversity and STBC is proposed. It is shown by simulation that compared to the traditional transmission scheme with signal space diversity and the STBC-encoded cooperative transmission scheme without signal space diversity, the new scheme can provide further performance improvement by increasing the diversity order, and can save more energy in wireless sensor networks.

One of the important sensor network applications is monitoring inaccessible environments. The noisy environment and energy constraints, however, challenge the event detection problem. Most of recently proposed fault-tolerant event detection algorithms are only based on the spatial correlation. In these algorithms, the frequent exchanges of measurements among nearby sensor nodes give rise to much energy dissipation. Moreover, detection accuracy is poor at the boundary of event region and the edge of sensor networks. In this paper, we propose a temporal-spatial correlation based fault-tolerant event region detection algorithm. In order to improve the performance, both spatial correlated information and temporal correlated information are employed in the event detection. It is validated through simulations that, the proposed temporal-spatial correlation based algorithm outperforms the spatial correlation based scheme in terms of detection accuracy and energy dissipation, thus making the proposed algorithm attractive in energy-efficient event region detection applications.

In mobile wireless sensor networks, sensors can move randomly or keep static temporarily. Mobility makes the sensor networks better acquire information, but also makes accurate localization more difficult since the network environment changes continually. In this paper, an energy-efficient dynamic simulation based localization (DSL) algorithm is introduced that uses range measurement information to restrict sample region and establishes a dynamic filtering mechanism to improve the localization performance and efficiency. Analytical and simulation results are provided to study the localization cost and location accuracy in different mobility models and various environmental settings. The results indicate that our algorithm outperforms the best known simulation based localization schemes under a wide range of conditions, with localization accuracy improved by an average of 24% and computation cost reduced significantly for a similar high localization accuracy.

In wireless sensor networks, time synchronization is a critical problem. In this paper, we propose SLTP, a Scalable Lightweight Time-synchr-onization Protocol for wireless sensor networks. By using passive clustering and linear regression SLTP can reduce the energy consumption of network nodes and also decrease the overhead of creating and maintaining the clusters. Moreover SLTP uses linear regression to compute the time. Therefore, it can calculate the clock skew and offset between each node and its cluster head in order to estimate the local time of remote nodes in the future or the past. Simulation results show that by this we can gain considerable improvements in power consumption, accuracy and scalability in comparison to similar algorithms.

Success of Wireless Sensor Networks largely depends whether the deployed network can provide desired coverage with acceptable network lifetime. This paper proposes a distributed protocol for ensuring area coverage using a combination of mobile and static sensor nodes. Most of the assumptions made in our approach are realistic (sensing model, movement thresholds based on real radio characteristics etc.) and implementable in real-life applications. We demonstrate that, for different type of initial deployments, our proposed movement algorithms consume only 30-40% of the energy consumed by the basic virtual force algorithm. We formulated our problem as Integer Linear Program to arrive at idealistic optimal solutions that form basis of our performance comparison. We validated our results through extensive discrete event simulations.

Many applications in wireless sensor networks require sensor nodes to obtain their absolute or relative positions. Although various localization algorithms have been proposed recently, most of them require nodes to be equipped with range measurement hardware to obtain distance information. In this paper, an area localization method based on Support Vector Machines (SVM) for mobile nodes in wireless sensor networks is presented. Area localization is introduced as an evaluation metric. The area localization procedure contains two phases. Firstly, the RF-based method is used to determine whether the nodes have moved, which only utilizes the value change of RSSI value rather than range measurement. Secondly, connectivity information and SVM algorithm are used for area localization of mobile nodes. The area localization is introduced to trade off the accuracy and precision. And area localization, as a new metric, is used to evaluate our method. The simulation experiments achieve good results.

Most existing mutual exclusion algorithms for mobile ad hoc networks (MANETs) adopt a token-based approach. In traditional wired networks, timeout-based mechanisms are commonly used to detect token losses. However, in MANETs, it is difficult to set a proper timeout value due to the network dynamics. In this paper, we propose a dual-token-based mutual exclusion algorithm, which can tolerate token losses without using timeout. Two tokens are concurrently circulated in the system to monitor each other by using sequence numbers. If one token is lost, the other token can detect the loss and regenerate a new token. Simulations have been carried out to evaluate the effectiveness and performance of the proposed algorithm in comparison with the timeout-based approach. The results show that the timeout-based algorithm may falsely claim the loss of a token, thus cannot guarantee the correctness of mutual exclusion algorithms. On the contrary, our proposed algorithm can avoid false detection of token losses and satisfy all the correctness requirements of mutual exclusion, though it costs a bit more messages and longer time.

Most of the current RSS (Received Signal Strength)-based localization algorithms in Wireless Sensor Networks (WSNs) rely on isotropic radio propagation model to infer the distance between a pair of nodes from received signal strength, which however has been proved to be quite unreliable in recent research work. Performance analysis is important to evaluate the applicability of a localization algorithm, however little work has been done on evaluating the existing localization algorithms in simulated realistic settings. This paper firstly presents the motivation and detailed implementation of a proposed Link-State Based Annulus (LSBA) localization algorithm, and then gives a panorama of performance comparison among LSBA and other four localization algorithms in terms of estimation error, convergence speed, computational complexity and communication cost in the simulated realistic environment. Simulation results show that LSBA achieves the best tradeoff among all the four metrics in WSNs with moderate number of anchors, and has good adaptability to irregular node deployment as well.

In wireless sensor network applications, effective clustering algorithm can reduce energy consumption, which can increase network scalability and lifetime. In most of traditional clustering methods, clusters do not form until their cluster heads are selected and these algorithms are usually running under the single data transmission mode. A clustering strategy for WSNs based on Fuzzy Cluster Mean (FCM) is proposed in this paper. It is a new clustering mechanism of generating the clusters first and then selecting the cluster head(CH). This strategy based on FCM has good characteristics of clustering quick, reducing energy consumption and being applied in different data transmission modes. The correctness and feasibility is validated in simulations. It is shown that energy consumption is better than the similar clustering algorithms. When different selection modes of CH are selected in this strategy, the clustering strategy based on FCM shows the best efficiency in two data transmission modes.

Mobile ad hoc networks must operate independent of fixed or centralized network management infrastructure, the communication between nodes rely on the node’s cooperation, so nodes’ selfish behavior to save the battery cost for their own communication cannot be neglect. However, general cooperation enforcement mechanisms do not consider node battery, so hotspot node issue may exist; even badly lead to network separation. This paper proposes an Energy Fairness Cooperation Enforcement Mechanism (EFCEM) in ad hoc networks. Theoretical analysis and numerical simulation results show that the EFCEM protocol, comparing with the traditional reputation mechanisms, can prolong networks existence time and improve network throughput, but at the cost of a little more packets delay.

Coverage is one of the most important issues in sensor networks. For random sensor deployment, one would like to know whether the deployed sensors can cover the whole field sufficiently. In this paper, we attempt to find a set of critical points in a sensor field so as to answer the yes/no question of complete coverage only by checking whether these points are covered, which is based on a new model of fuzzy information coverage. The higher order Voronoi diagram is analyzed and a sufficient condition is provided for a sensor field which is completely fuzzy information covered by a given set of sensors. The corresponding algorithm in

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N+NlogN) runtime is also presented.

RFID, as an emerging technology, has very huge potential in today’s social and business developments. Security and Privacy are one of the important issues in the design of practical RFID protocols. In this paper, we focus on RFID authentication protocol. RFID mutual authentication is used to ensure that only an authorized RFID reader can access to the data of RFID tag while the RFID tag is confirmed that it releases data to the authenticated RFID reader. This paper will propose an anonymous mutual authentication protocol for RFID tag and reader. RFID tag is anonymous to RFID reader so that privacy can be preserved. In addition, mutual authentication does not need to rely on a back-end database.

Providing easy access to the Internet is a prerequisite for successful deployment of Mobile Ad-hoc Networks (MANET). This paper proposes an Identifiers Separating and Mapping Scheme (ISMS) based Internet access solution for MANET, called ISMS-MANET. Firstly, ISMS, which is a candidate for the future Internet architecture, is briefly described. Then, how the Ad hoc On-Demand Distance Vector (AODV) routing protocol can be used for connecting a MANET to the ISMS based Internet is discussed. In ISMS-MANET, the Access Router (AR) implements AODV protocol and works like a normal MANET node. The node in the MANET relies on the Route Reply message of AODV to find the AR. A prototype system is implemented. Performance analysis shows that ISMS-MANET has much faster handover and lower packet processing delay than the Mobile-IP based solution.

In sensor networks, queries need to be jointly designed, in order to minimize the power consumption and maximize the lifetime. Data reduction techniques can be employed to decrease the size of data to be transferred in the network, and therefore save energy of sensor nodes. This paper presents a novel method for optimizing multi-query in sensor networks. Our approach is, by using packet combination techniques, to reduce the data size of multiple simultaneous queries, so that the energy for data transmission can be saved to the best extent. A delay item is specified together with the query by the application. Then an optimal query plan can be obtained by studying the best time of sending local data to sink that can lead to the minimum cost. Algorithm is described in detail. Performance analysis is performed to validate the effectiveness of the proposed method.

It is common that a small group of autonomous mobile units requires location information of each other, but it is often not applicable to build infrastructure for location service. Hence, mobile units use RF signals to determine their relative positions within the group. Several techniques have been proposed for localization, but none of them consider both units mobility and anchor unavailability. In this paper we develop a propagation scheme for spreading the signal strength information through the network, and filtering techniques are employed to process the noisy signal. We use Floyd-Warshall algorithm to generate pairwise signal distance of each pair of units. Then Multidimensional Scaling technique is used to generate relative position from pairwise distances. Due to anchor unavailability, relative positions are adjusted by certain rules to reflect the continuous mobility. We verify our methods in MICAz platform. Experimental results show that we can obtain smooth relative positions under mobility and manage moving patterns of mobile units.

Wireless Sensor networks are gaining a role of importance in the research community. In this paper, we choose Imote2 to establish our testbed according to the analysis and the comparison of the hardware capabilities and software characteristics of the current WSNs products. Moreover, we present our hardware, software platforms and “30 motes” testbed to validate and evaluate our Fully Integrated Scheme of self-Configuration and self-Organization (FISCO) while further propose the rudiment of our general routing and data dissemination testbed. In the test stage, experimental results show that each mote in the network obtains the corresponding role and takes correct actions to handle every receiving message.

Sensor Web, as an extension of Sensor Networks, is expected to be used in the distributed, large-scale environment. With the help of Internet, its application can even be extended to the world wide. And in the distributed environment, a Sensor Web usually consists of different sensor networks or single sensor owned by different organizations such as research institutions, companies or even individual user. So maximizing their benefits is what the sensors most concern about. In other words, the sensors in Sensor web are rational and selfish. In this paper, we discuss the selfish problems of Sensor Web and resolve them using specific designed mechanism. We describe several scenarios of the applications in Sensor Web and consider the variable cost and value issues which are, to the best of our knowledge, first time studied in the Sensor Web. In the end, our mechanisms are proved to be truthful and can be extended to many other applications.

Position information in sensor networks is crucial for many applications. A large number of localization algorithms have been developed, however, most of them need special measurement tools and could not work well in irregularly shaped sensor networks. In this paper, we present an Enhanced DV-hop Localization Algorithm (EDLA) to deal with irregularly shaped network topology. With the same process of DV-hop, a reference node of EDLA can delimit approximate regular shaped regions as convex hulls. Based on the inclusion test within convex hulls, the expected average per-hop distance information is disseminated by qualified relay nodes and used for position estimation. Simulation results show that the proposed localization method outperforms DV-hop and PDM(proximity-distance map) in irregularly-shaped sensor networks if both the localization error and computational complexity are considered.

In this paper we focus on the survivability of wireless sensor networks, with particular emphasis on industries requirements. we develop a model to evaluate the tradeoffs between the cost of defense mechanisms for Wireless Sensor Network and the resulting expected survivability after a network attack. The model consists of three parts. The first part simulates the occurrence of attacks or incidents. The second part simulates the impact of an attack on the WSNS which depends on the type of attack and the defense mechanism installed in the network. And the third part assesses the survivability of the system which depends on the degree of its degradation after the attack. We demonstrate through simulation the model’s effectiveness in mitigating attacks.

Some of the routing algorithms in mobile ad hoc networks use multiple paths simultaneously. These algorithms can attempt to find node-disjoint paths to achieve higher fault tolerance capability. By using node-disjoint paths, it is expected that the end-to-end delay in each path should be independent of each other. However, because of natural properties of wireless media and medium access mechanisms in ad hoc networks, the end-to-end delay between any source and destination depends on the pattern of communication in the neighborhood region. In this case some of the intermediate nodes should be silent to reverence their neighbors and this matter increases the average of end-to-end delay. To avoid this problem, multi-path routing algorithms can use zone-disjoint paths instead of node-disjoint paths. Two routes with no pair of neighbor nodes are called zone-disjoint paths. In this paper we propose a new multi-path routing algorithm that selects zone-disjoint paths, using omni-directional antenna. We evaluate our algorithm in several different scenarios. The simulation results show that the proposed approach is very effective in decreasing delay and packet loss.

The use of proxies is commonplace in today’s MANETs, where they are used for a huge variety of network services. However the main problem of using proxies is that the end-to-end nature of the communication is broken. This leads to some severe security problems. One of the main questions that arise is how content caching by intermediaries can be done when end-to-end security is required.

In this paper, we will address the research issues of when and how end-to-end security, like confidentiality and authenticity can be preserved, in mobile ad hoc network communications, when having one or more cache proxies and router nodes in the data path.

We propose a solution for an encryption scheme based on Asymmetric Cipher Sequence which allows to an intermediary nodes to cache data and convert the ciphertext for one person into the ciphertext for another person without revealing the secret decryption keys or the plaintext.

Implementation results shows that we can simultaneously achieve high encryption through a wireless links.

We have developed a self-healing key distribution scheme for secure multicast group communications for wireless sensor network environment. We present a strategy for securely distributing rekeying messages and specify techniques for joining and leaving a group. Access control in multicast system is usually achieved by encrypting the content using an encryption key, known as the group key (session key) that is only known by the group controller and all legitimate group members. In our scheme, all rekeying messages, except for unicast of an individual key, are transmitted without any encryption using one-way hash function and XOR operation. In our proposed scheme, nodes are capable of recovering lost session keys on their own, without requesting additional transmission from the group controller. The proposed scheme provides both backward and forward secrecy. We analyze the proposed scheme to verify that it satisfies the security and performance requirements for secure group communication.

Using polynomial-based key predistribution in distribution sensor networks for reference, this paper presents an efficient key predistribution scheme for Ad hoc networks: a multigrid-based key predistribution scheme. In this scheme we put forward the concept of multi-grid on which our key predistribution scheme is upbuilt, and the first time threshold scheme is introduced into the process of key transfer. The analysis in this paper indicates that this scheme has a number of nice properties, including high probability to establish pairwise keys, tolerance of node captures, and low communication overhea.

Recently, position-based routing has proven to be a scalable and efficient way for packet routing in mobile ad hoc networks. To enable position-based routing, a node must be able to discover the location of the intended destination node. This can typically be accomplished by a location service. By far there have been many efficient location service algorithms such as the DREAM, RLS, Homezone, GLS, DLM and HLS, but most of them have focused on the scalability and efficiency of algorithm while the security and privacy issues were vastly neglected. In this article, we propose a secure privacy-preserving hierarchical location service (SPPHLS) based on the HLS algorithm using the broadcast encryption scheme and broadcast authentication scheme. In the proposed secure location service scheme, the position privacy of nodes is protected and the security is promised. Finally, through simulation and analysis, we further show that the proposed scheme only introduces very moderate success rate degradation and query delay compared to the original HLS algorithm.

The framework of security communication among sensor nodes is the most important aspect and a basic research field of securing Wireless Sensor Networks. Many techniques have been developed recently to establish keys in sensor networks. Most of them are based on cluster topology. Based on the novel loop-topology, this paper proposes a new key establishment and rekeying scheme. The loop-based scheme has many advantages over cluster-based scheme. The analysis in this paper demonstrates its feasibility, efficiency and security for key establishment and maintenance in Wireless Sensor Networks.

To increase the lifespan of wireless sensor networks (WSN) and preserve the energy of sensors, data aggregation techniques are usually used. Aggregation can be seen as the process by which data sent from sensors to the BS are little-by-little processed by some nodes called aggregator nodes. Aggregators collect data from surrounding nodes and produce a small sized output, thus preventing that all nodes in the network send their data to the BS. Security plays a major role in data aggregation process, especially that aggregators are more attractive for attackers than normal nodes, where compromising few aggregators can significantly affect the final result of aggregation. In this paper, we present SAPC, a secure aggregation protocol for cluster-based WSN, which does not rely on trusted aggregator nodes and thus is immune to aggregators compromising. In addition to security performance, SAPC has a low transmission overhead.

In this paper, we investigate the use of Aspect-Oriented Programming (AOP) [13] in the domain of Mobile Ad-hoc NETworks (MANETs). More precisely we study the availability issues in Proactive routing protocols. This paper classifies the different possible attacks and examines the countermeasures to ensure availability. Our approach is based on a detection-reaction process. The reasoning followed by the detection process is built on a formal description of normal and incorrect node behaviors. This model allows us to derive security properties. These properties are woven into our implementation using the AOP. Our algorithm checks if these security properties are violated. If they are, detection of incorrect (malicious) behaviors occurs to allow the normal node to find a path without incorrect node behavior. Therefore the detector node sends to its neighborhood the detection information to allow its neighbors to avoid choosing the intruder as a node to cross to. A node chooses the path using its local diagnosis and the reputation of other nodes. Using a field in the standard control message to communicate the detections, our approach does not change the message format, so it is very easy to use and there is no overhead. While we use OLSR as an example of protocol for our studies, we argue that the presented techniques apply equally to any proactive routing protocol for MANETs.

Deploying wireless LANs (WLAN) at large scale is mainly affected by reliability, availability, performance, and security. These parameters will be a concern for most of managers who want to deploy WLANs. Most importantly, the security issue became the predominant factor in WLAN design. Different Intrusion detection mechanisms have been addressed in research papers, but with little being focused on internal intrusion and prevention. In this paper an efficient security method has been proposed. It is based on detecting rogue access points as well as rogue bridge access points and denying their access to the WLAN. In addition a new method of mutual authentication between DHCP server at the AP and wireless client has been introduced. This would allow client to detect rogue DHCP server and stop the association with it. It also allows registered DHCP server to detect unauthorized client and deny its request. Moreover the DHCP server would synchronize with the AP or intelligent LAN switch to drop packets from unauthorized client who might use static IP to get access to the network.

In this paper we discuss the uprising problem of public key revocation. The main problem in key revocation includes the relatively large memory and communication required to store and transmit the revoked list of keys. This problem becomes serious as the sensor network is subjected to several constraints. In this paper, we introduce several efficient representation mechanisms for representing a set of revoked identifiers of keys. We discuss several network and revocation scenarios and introduce the corresponding solution for each. To demonstrate the value of our proposed approaches, practical simulation results and several comparisons with the current used revocation mechanism are included.

Improvements in technology introduce new application for sensor networks. As Mission-critical applications are deployed in distributed wireless sensor networks, security issues arise. They are facing tremendous challenges: wireless communication environment (usually in hostile areas), lack of infrastructure support, inability of predicting network topology and limited resource associated with nodes. Efficient and robust key distribution is important to secure such kind of sensor networks. To address this issue, we propose a simple pair-wise key distribution and management approach. We predistribute an INITIAL_KEY and a PRIVATE_KEY to each sensor. Let each sensor broadcast its encrypted PRIVATE_KEY with limited power. Then every sensor shares a pair-wise key with each of its neighbors. Any pair of adjacent nodes could communicate securely using a common pair-wise key. Node addition and deletion during communication stage are supported, so as to the update of pair-wise keys. Simulation result proves the scalability of our method.

As the WSN multi-media applications go deep into the military, monitor and other data-sensitive areas, stream data have become the main data processing objects instead of scalar data in WMSN. Because of the difference between the application environments and data features of stream data and scalar data, traditional secure routing for scalar data is not fit for stream data. In this paper, SOAR, a secure route for the false data injection attack model is presented. SOAR works in the stream data transfer mode and randomly detects the false data injection attacks. SOAR guarantees that the base stations receive small percentage of false packages with rather low load.

The growing popularity of wireless sensor networks has brought increasing attention to many security issues for such networks. In these security issues, key management is one of the most challenging and in dire need of solving problems. A lot of research has been mainly concentrated on key management for homogeneous wireless sensor networks. However, such homogeneous networks could restrict them to have a long network lifetime as well as to improve network connectivity. Recent research has shown that heterogeneous wireless sensor networks have greater performance and reliability. In this paper, we propose a key management scheme for heterogeneous wireless sensor networks to improve the random key pre-distribution scheme using deployment knowledge of nodes and the prior area deployment information. The performance evaluation and security analysis show that our scheme can substantially improve the network connectivity with low complexity and significant reduction on storage requirement, and enhance the network resilience against node capture, compared with existing key management schemes.