Energy-Aware Georouting with Guaranteed Delivery in Wireless Sensor Networks with Obstacles

We propose, end-to-end (EtE), a novel EtE localized routing protocol for wireless sensor networks that is energy-efficient and guarantees delivery. To forward a packet, a node s in graph G computes the cost of the energy weighted shortest path (SP) between s and each of its neighbors in the forward direction towards the destination which minimizes the ratio of the cost of the SP to the progress (reduction in distance towards the destination). It then sends the message to the first node on the SP from s to x: say node x′. Node x′ restarts the same greedy routing process until the destination is reached or an obstacle is encountered and the routing fails. To recover from the latter scenario, local minima trap, our algorithm invokes an energy-aware Face routing that guarantees delivery. Our work is the first to optimize energy consumption of Face routing. It works as follows. First, it builds a connected dominating set from graph G, second it computes its Gabriel graph to obtain the planar graph G′. Face routing is invoked and applied to G′ only to determine which edges to follow in the recovery process. On each edge, greedy routing is applied. This two-phase (greedy–Face) EtE routing process reiterates until the final destination is reached. Simulation results show that EtE outperforms several existing geographical routing on energy consumption metric and delivery rate. Moreover, we prove that the computed path length and the total energy of the path are constant factors of the optimal for dense networks.

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Maximizing network utilization with max–min fairness in wireless sensor networks

The state-of-the-art for optimal data-gathering in wireless sensor networks is to use additive increase algorithms to achieve fair rate allocation while implicity trying to maximize network utilization. For the quantification of the problem we present a receiver capacity model to capture the interference existing in a wireless network. We also provide empirical evidence to motivate the applicability of this model to a real CSMA based wireless network. Using this model, we explicitly formulate the problem of maximizing the network utilization subject to a max–min fair rate allocation constraint in the form of two coupled linear programs. We first show how the max–min rate can be computed efficiently for a given network. We then adopt a dual-based approach to maximize the network utilization. The analysis of the dual shows the sub-optimality of previously proposed additive increase algorithms with respect to bandwidth efficiency. Although in theory a dual-based sub-gradient search algorithm can take a long time to converge, we find empirically that setting all shadow prices to an equal and small constant value, results in near-optimal solutions within one iteration (within 2% of the optimum in 99.65% of the cases). This results in a fast heuristic distributed algorithm that has a nice intuitive explanation—rates are allocated sequentially after rank ordering flows based on the number of downstream receivers whose bandwidth they consume. We also investigate the near optimal performance of this heuristic by comparing the rank ordering of the source rates obtained from the heuristic to the solutions obtained by solving the linear program.

From link dynamics to path lifetime and packet-length optimization in MANETs

We present an analytical framework and statistical models to accurately characterize the lifetime of a wireless link and multi-hop paths in mobile ad hoc networks (MANET). We show that the lifetimes of links and paths can be computed through a two-state Markov model. We also show that the analytical solution follows closely the results obtained through discrete-event simulations for two mobility models, namely, random direction and random waypoint mobility models. We apply these models to study practical implications of link lifetime on routing protocols. First, we compute optimal packet lengths as a function of mobility, and show that significant throughput improvements can be attained by adapting packet lengths to the mobility of nodes in a MANET. Second, we show how the caching strategy of on-demand routing protocols can benefit from considering the link lifetimes in a MANET. Finally,we summarize all the analytical results into a comprehensive performance analysis on throughput, delay and storage.

Minimum Path Exposure and Detection Interval Setting for Target Detection Using Wireless Sensor Network

Sensor network generally detects target at a fixed frequency. Detection interval means time spacing between two adjacent detection attempts. While designing a sensor network for detection of target intrusion in a specific region, the interval should be carefully set with trade-off between power consumption and detection performance. This is because redundant power may be consumed if it is too short and the target may be missed if too long. In this paper, we study the determination of the maximum detection interval (MDI) with specified detection performance. Path exposure is adopted as a performance metric. For detection-oriented application, a novel method to evaluate the minimum path exposure (MPE) is developed. Then the MDI problem is formulated and its solution is presented. The factors influencing the MDI are extensively simulated.

Scheduling for information gathering on sensor network

We investigate a unique wireless sensor network scheduling problem in which all nodes in a cluster send exactly one packet to a designated sink node in an effort to minimize transmission time. However, node transmissions must be sufficiently isolated either in time or in space to avoid collisions. The problem is formulated and solved via graph representation. We prove that an optimal transmission schedule can be obtained efficiently through a pipeline-like schedule when the underlying topology is either line or tree. The minimum time required for a line or tree topology with nodes is . We further prove that our scheduling problem is NP-hard for general graphs. We propose a heuristic algorithm for general graphs. Our heuristic tries to schedule as many independent segments as possible to increase the degree of parallel transmissions. This algorithm is compared to an RTS/CTS based distributed algorithm. Preliminary simulated results indicate that our heuristic algorithm outperforms the RTS/CTS based distributed algorithm (up to 30%) and exhibits stable behavior.

Design and Evaluation of DNS as Location Manager for HIP

Host Identity Protocol (HIP) is designed to provide secure and continuous communication by separating the identifier and locator roles of the Internet Protocol (IP) address. HIP also has efficient solutions to support host mobility. In this paper, we propose a location management scheme based on Domain Name System (DNS) for HIP. In the proposed scheme, a new DNS HIP resource record is used to translate a domain name into a host identity tag and an IP address. We also develop an analytical model to study the performance of DNS as location manager in terms of success rate, which takes into account the velocity of mobile nodes, the radius of a subnet, the regional network size, the packet transmission delay between the mobile node and the rendezvous server, and the packet processing delay at the DNS and the rendezvous server. The performance results show that for a reasonable range, the DNS is a feasible solution for location management with high success rate for HIP.

Fixed and dynamic bandwidth allocation strategies for wireless mobile integrated services networks

Performance evaluation of two bandwidth allocation strategies in wireless mobile integrated services networks is carried out. Performances of the proposed strategies are compared with those of the traditional guard channels and threshold strategies. In the study, a single wireless cell which is accessed by voice and non-voice traffic types producing, respectively narrowband and wideband calls is considered. In the proposed strategies a number of channels are reserved in a fixed or dynamic fashion for the use of originating wideband calls in addition to the guard channels allocated for the handoff calls. The results indicate that the two strategies have comparable advantages and by manipulating the number of reserved channels, desired performance levels can be achieved. The dynamic reservation based strategy makes the system fairer for the originating wideband calls while maintaining low handoff dropping probability and acceptable channel utilization levels. On the other hand, the fixed reservation strategy provides a lower handoff call dropping at comparable channel utilization levels. The tradeoff is between improving the handoff call dropping versus the originating wideband call blocking. Both strategies provide better performance for the originating wideband calls compared with that provided by the traditional guard channels strategy.

A game-theoretic analysis of denial of service attacks in wireless random access

In wireless access, transmitter nodes need to make individual decisions for distributed operation and do not necessarily cooperate with each other. We consider a single-receiver random access system of non-cooperative transmitters with the individual objectives of optimizing their throughput rewards, transmission energy costs and delay costs. The non-cooperative transmitter behavior may be purely selfish or may also reflect malicious objectives of generating interference to prevent the successful transmissions of the other nodes as a form of denial of service attack. Our goal is to evaluate the interactions between selfish and malicious nodes that have the dual objectives of optimizing their individual performance measures and blocking the packet transmissions of the other selfish nodes. We assume saturated packet queues of infinite buffer capacities and consider a general multi-packet reception channel that allows packet captures in the presence of simultaneous transmissions. In this context, we formulate a non-cooperative random access game of selecting the individual probabilities of transmitting packets to a common receiver. We derive the non-cooperative transmission strategies in Nash equilibrium. The analysis provides insights for the optimal strategies to block random access of selfish nodes as well as the optimal defense mechanisms against the possible denial of service attacks of malicious nodes in wireless networks. The results are also compared with the cooperative equilibrium strategies that optimize the total system utility (separately under random access and scheduled access). A pricing scheme is presented to improve the non-cooperative operation. For distributed implementation, we formulate a repeated game of the best-response strategy updates and introduce adaptive heuristics (based on the channel feedback only) provided that the system parameters are not explicitly known at the individual transmitters.

Integrated power and handoff control for next generation wireless networks

In this paper, joint downlink power control and handoff design is formulated as optimization problems that are amenable to dynamic programming (DP). Based on the DP solutions which are impractical, two new algorithms suitable for next generation wireless networks are proposed. The first one is an integrated hard handoff/power control scheme that endeavors a tradeoff between three performance criteria: transmitted power, number of handoffs, and call quality. The second is a soft handoff/power control algorithm that also takes into account the additional cost of utilizing soft handoff. The proposed algorithms present a paradigm shift in integrated handoff/power control by capturing the tradeoff between user satisfaction and network overhead, therefore enjoy the advantages of joint resource allocation, and provide significant improvement over existing methods. The achievable gains and the tradeoffs in both algorithms are verified through simulations.

Cluster-Based Autoconfiguration for Mobile Ad hoc Networks

IP address autoconfiguration of mobile nodes is highly desirable in the practical usage of most mobile ad hoc networks (MANETs). This paper proposes cluster-based autoconfiguration, a novel approach for the efficient address autoconfiguration of MANETs. The cluster structure derived from clustering techniques is used to manage address assignment and conflict resolution. By introducing the concept of virtual address agents (AAs), the proposed approach can be applicable to many existing clustering protocols. Finally, analysis and simulation demonstrate that the proposed scheme outperforms the previous autoconfiguration approaches.

Some New Expressions for Nakagami Fading Based on Order Statistics

Alternative representations based on order statistics are derived for the probability of error for orthogonal, biorthogonal, and transorthogonal signaling. Short programs in are developed for the computation of these representations and to furnish evidence to show that their performance is superior to the traditional Monte Carlo approach.

HASP Overlay Cell Over Wireless ATM Microcellular Networks: A Proposed Architecture for Priority Subscribers

Wireless ATM (W-ATM) microcellular networks encounter severe problems during handovers. Microcellular solutions in W-ATM networks increase the network traffic control as a result of frequent handover requests. This paper presents a two-layer microcellular ATM architecture which optimizes the handoff blocking probability performance of priority subscribers (PS) in a congested urban area. The lower layer of the proposed architecture is based on a microcellular ATM solution for normal subscribers (NS) while the higher layer is based on a high altitude stratospheric platform (HASP) overlay solution for absorbing the traffic load of the existed handoff calls of PS. Analysis is performed using Markov state diagrams, in order to optimize the performance of W-ATM networks.

Potential Cognitive Radio Denial-of-Service Vulnerabilities and Protection Countermeasures: a Multi-dimensional Analysis and Assessment

Cognitive radios sense spectrum activity and apply spectrum policies in order to make decisions on when and in what bands they may communicate. These activities go beyond what is done when traditional radios communicate. This paper examines the denial of service vulnerabilities that are opened by these additional activities and explores potential protection remedies that can be applied. An analysis of how vulnerable are victim cognitive radios to potential denial of service attacks is presented along different axis, namely the network architecture employed, the spectrum access technique used and the spectrum awareness model. The goal is to assist cognitive radio designers to incorporate effective security measures now in the early stages of cognitive radio development.

On Address Privacy in Mobile Ad Hoc Networks

The network addresses of principals in a mobile ad hoc network (MANET) are conventionally assumed to be public information. This may cause devastating consequences for MANETs deployed in hostile environments. For example, attackers can easily locate a target principal based his known network address and then launch a pinpoint attack. This paper identifies address privacy as a new security requirement to prevent attackers from ascertaining network addresses of MANET principals. We further present Swarms, the first solution to satisfying this requirement. Swarms eliminates the conventionally explicit one-on-one mappings between MANET principals and network addresses and allows any two principals to communicate while blind to each other’s address. We quantitatively measure the address privacy offered by Swarms via an entropy-based information-theoretic metric.

On the Performance of Broadband Mobile Internet Access System

In this paper, we evaluate the performance of OFDMA/TDD-based broadband mobile internet access system with the features of adaptive modulation & coding (AMC) and hybrid ARQ. We present a framework of system-level simulation and furthermore, intend to derive the insightful results towards understanding the performance of broadband mobile internet access system. The average system throughput as well as delay performance is evaluated for the different channel characteristics and system parameters, which allows for predicting the system capacity in the varying cellular network environment.

Seamless Streaming Media for Heterogeneous Mobile Networks

As the mobile networking technologies evolve, people are able to access the Internet through heterogeneous wireless access networks, such as WLAN, GPRS, 3G and Beyond 3G networks. For the coverage, bandwidth and cost of these heterogeneous mobile access networks are quite different, a mobile host may hand over among them, and this is called vertical handoffs. One of the most important issues for heterogeneous mobile networks is that vertical handoffs may degrade the quality of the time-sensitive streaming media services, even interrupt them. To overcome the problem, in the paper a multicast-based redundant streaming architecture is proposed. The proposed architecture is implemented in the all-IPv6 heterogeneous mobile networks. Five experiments are performed to evaluate the performance of the proposed architecture. The experimental results and the analysis show that the proposed architecture is capable of providing seamless streaming services even if the vertical handoffs or the traffic congestion occurs. Moreover, it is found that the traffic overhead is only 1.0368% per vertical handoff for each mobile access network, and thus the feasibility of the proposed architecture is demonstrated.

Ad hoc networks beyond unit disk graphs

In this paper, we study an algorithmic model for wireless ad hoc and sensor networks that aims to be sufficiently close to reality as to represent practical realworld networks while at the same time being concise enough to promote strong theoretical results. The quasi unit disk graph model contains all edges shorter than a parameter d between 0 and 1 and no edges longer than 1. We show that—in comparison to the cost known for unit disk graphs—the complexity results of geographic routing in this model contain the additional factor 1/d ². We prove that in quasi unit disk graphs flooding is an asymptotically message-optimal routing technique, we provide a geographic routing algorithm being most efficient in dense networks, and we show that classic geographic routing is possible with the same asymptotic performance guarantees as for unit disk graphs if .

A New Buffer Algorithm for Speech Quality Improvement in VoIP Systems

Jitter buffer plays an important role in Voice over IP (VoIP) applications because it provides a key mechanism for achieving good speech quality to meet technical and commercial requirements. The main objective of this paper is to propose a new, simple-to-use jitter buffer algorithm as a front-end to conventional static or adaptive jitter buffer algorithms to provide improved performance, in terms of enhanced user-perceived speech quality and reduced end-to-end delay. Supported by signal processing features, the new algorithm, the so-called Play Late Algorithm, alters the playout delay inside a speech talkspurt without introducing unnecessary extra end-to-end delay. The results show that the new algorithm achieves the best performance under different network conditions when compared to conventional static and adaptive jitter buffer algorithms. The results reported here are based on live tests and emulated network conditions on real mobile phone prototypes. The mobile phone prototypes use AMR codec and support full IP/UDP/RTP stack with IPSec function in some of the tests. The method for perceived speech quality measurement is based on the ITU-T standard for speech quality evaluation (PESQ).

Real-time resource allocation for LEO satellite constellations

The paper addresses the need of controling the access of terminals with guaranteed ressources on the high dynamic systems offered by LEO satellite constellations. A call-access-control scheme that guarantees the reservation of permanent resources of satellite constellations in $O(\sqrt(n)\hbox{log}(n))The paper addresses the need of controling the access of terminals with guaranteed ressources on the high dynamic systems offered by LEO satellite constellations. A call-access-control scheme that guarantees the reservation of permanent resources of satellite constellations in time, where n is the number of user present in the system, is described. A tradeoff between computational time of call-access-control and optimization of the use of the spectrum is identified. Some experimental results are presented.

Jér?me GaltierEmail:

     

Information-based connection algorithm for supporting QoS in nested mobility network

A multihop mobile wireless network can be a collection of wireless mobile nodes forming a temporary network without the aid of any established infrastructure or centralized administration. Mobile nodes communicate with each other using multihop wireless links. Each mobile node in the network also acts as a router, which forwards data packets to other nodes. A main challenge in the design of this mobile network is the development of dynamic routing protocols that can efficiently find routes between two communicating nodes that often change the network topology drastically and unpredictably. All communications between the nodes inside the mobile network and the global Internet must be maintained, although the mobile router (MR) connecting the other mobile network to the global Internet must change their address; and mobile nodes suffer from end-to-end delay and handoff delay. That is to say, hereafter the packets sailing for the mobile node would not be routed directly for the destination, but will always make a detour by way of HA to the target node. In this paper, we suggest Information-based Connection Algorithm that adds keyword management method in order to resolve such a problem, simulations are carried out with NS-2 for performance evaluation. The results of the simulations show an improvement on throughput and handoff delay, and consequently the QoS improvement.