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Wireless Communications and Mobile Computing Conference, 2008. IWCMC '08. International

Date 6-8 Aug. 2008

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Displaying Results 1 - 25 of 196
  • IWCMC - Title Page

    Publication Year: 2008 , Page(s): 1
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  • 2008 Copyright

    Publication Year: 2008 , Page(s): 2
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  • Welcome

    Publication Year: 2008 , Page(s): 3 - 4
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  • Sponsors

    Publication Year: 2008 , Page(s): 5
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  • Technical program

    Publication Year: 2008 , Page(s): 6 - 27
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  • Convex Approximation-Based Joint Power and Admission Control for Cognitive Underlay Networks

    Publication Year: 2008 , Page(s): 28 - 32
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    The joint power and admission control problem is considered for a cognitive underlay scenario, under Quality of Service (QoS) constraints for both primary and secondary users. Primary users must be guaranteed a premium service rate, measured by their signal to interference plus noise ratio (SINR); secondary users, if admitted, should be provided with at least a basic service rate, and the number of admitted secondary users should be maximized. The problem is NP-hard, but drawing upon recent results for joint beamforming and admission control for the cellular downlink, an efficient convex approximation algorithm is derived that yields close to optimal results at affordable complexity. The key step is a reformulation of the joint problem that naturally leads to a linear programming relaxation. Simulation results are included to illustrate the merits of the approach. Two scenarios are considered: with or without a primary user. In the latter, several good heuristic algorithms are available in the literature, and the prevalent one is used as a baseline. A brute- force enumeration algorithm is used in both cases to assess the gap to the optimal solution. View full abstract»

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  • Asymptotically Optimal Policies for Wireless Networks with Rechargeable Batteries

    Publication Year: 2008 , Page(s): 33 - 38
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB) |  | HTML iconHTML  

    We consider the problem of cross-layer resource allocation for single-hop, time-varying, wireless networks operating with rechargeable batteries under general arrival, channel and recharge processes. The objective is to maximize total system utility, as a function of the long-term rate achieved per link, while satisfying energy and power constraints. A policy with decoupled admission control and power allocation decisions is proposed that achieves asymptotic optimality for sufficiently large battery capacity to maximum power ratio (explicit bounds are provided). This policy is particularly suitable for satellite downlinks or sensor networks, which are most likely to satisfy the above condition. An extension to multihop networks is briefly described as well. View full abstract»

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  • Network Coding for Dynamically Changing Networks

    Publication Year: 2008 , Page(s): 39 - 44
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    We here advocate the case for network coding as a guiding paradigm for the operation of networks that vary in a small time frame, due to node mobility, channel variations, and varying traffic conditions. Three ideas that appeared succesively in time brought in place an elegant operation for network coding in such environments. These are, use of randomized network coding for intermediate node operation, use of generations to avoid synchronization, and use of subspace coding to allow for small packet sizes. Information theoretical performance limits support these results. View full abstract»

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  • Wireless Sensor Networks with Distributed Decision Capabilities Based on Self Synchronization of Relaxation Oscillators

    Publication Year: 2008 , Page(s): 45 - 49
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    The goal of this paper is to show that a distributed consensus mechanism can be implemented in a wireless sensor network exploiting the synchronization capabilities of relaxation oscillators, properly initialized with the measurements taken by their associated sensors. Relaxation oscillators are dynamic systems characterized by testability and high flexibility to produce waveforms with different characteristics. In particular, initializing each system with a function of the measurement, the state of the system may end up into two possible stable trajectories: a constant waveform, corresponding to a stable equilibrium point, or a periodic waveform, corresponding to a limit cycle. In the first case, the node does not transmit any signal. Conversely, in the second case, the node transmits a periodic signal like, e.g., a train of pulses. The approach proposed in this work has two purposes: a) design the oscillators' parameters so that they do not transmit when the measurement falls below a given threshold or they transmit a periodic pulse train, with a period inversely proportional to the measurement, when the measurement exceeds the threshold; b) make nearby oscillators to interact with each other in order to reach a consensus over globally optimal test statistics. Finally, the proposed scheme is applied to distributed multiple hypothesis testing for the recognition of the field monitored by a planar sensor network. View full abstract»

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  • Robust Stochastic Routing and Scheduling for Wireless Ad-Hoc Networks

    Publication Year: 2008 , Page(s): 50 - 55
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    We discuss the design of robust protocols that despite poor knowledge about network connectivity achieve consistent performance. Optimal routes and schedules are obtained to (i) maximize a social network utility subject to a variance constraint; and (ii) minimize a variance cost subject to a minimum yield. Corresponding optimization problems are formulated and shown to be convex under mild conditions usually satisfied in practice. Protocols are obtained relying on dual decomposition algorithms that compute the solution of these optimization problems in a distributed manner. The resulting protocols yield utilities that come close to the prescribed requirement even when channel estimates are rough. View full abstract»

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  • Approximate Characterization of Capacity in Gaussian Relay Networks

    Publication Year: 2008 , Page(s): 56 - 61
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    One of the distinguishing features of wireless communication is its broadcast nature. This creates complicated signal interactions when there are multiple transmitting and receiving nodes, due to superposition of signals at the receivers. In this paper, we focus on wireless relay networks where (relay) nodes facilitate communications between a source and a destination. We review some recent progress on this problem. The progress is made by developing simpler models which give insight and facilitate an approximate characterization of network capacity. We have developed deterministic models that (approximately) capture these interactions and show that for such models, one can obtain an information-theoretic max-flow min-cut result, in analogy to the classic wire-line Ford-Fulkerson result. We have extended these ideas to networks with general deterministic (interaction) functions. Using insights from the analysis of deterministic networks, we develop an approximate characterization for noisy Gaussian relay networks showing that the achievable rate is within a constant number of bits from the information- theoretic cut-set upper bound on the capacity of these networks. This constant depends on the topology of the network, but not on the values of the channel gains. View full abstract»

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  • Cochannel Interference Avoidance MAC in Wireless Cellular Networks

    Publication Year: 2008 , Page(s): 62 - 67
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (245 KB) |  | HTML iconHTML  

    Severe cochannel interference in wireless cellular networks significantly affects users at cell edges. We propose a cost-effective cochannel interference avoidance (CIA) medium access control (MAC) scheme to improve network performance. For CIA-MAC, base stations judged as severe interferers transmit randomly and transmission is controlled by wireless channel states to optimize the overall network performance while maintaining proportional fairness amongst users. The conditions for triggering CIA-MAC are derived and two simple trigger mechanisms are obtained. The CIA-MAC scheme requires low signalling overhead and only minor changes to the existing mobile systems. Simulation results show that the proposed scheme, CIA-MAC, significantly outperforms traditional networks through avoidance of severe cochannel interference as well as exploitation of multiuser diversity through cross-layer design. View full abstract»

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  • Performance Analysis of Next Generation Mobility Protocols for IMS/MMD Networks

    Publication Year: 2008 , Page(s): 68 - 73
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (329 KB) |  | HTML iconHTML  

    In an effort to provide seamless mobility support in IMS/MMD networks, operators need to choose a specific IP- based mobility protocol. However, there are several micro- and macro-mobility protocols available that the operators can choose from. Operators often face the challenges of selecting the appropriate mobility protocol that can provide the most cost efficient solution under a specific operating environment. Thus, it is important to analyze the effectiveness of these protocols before they are actually deployed in the IMS/MMD networks. In this paper, we analyze a number of candidate mobility protocols and conduct a performance analysis of some of these using a prototype implementation in an IPv6-based IMS/MMD testbed. These analyses provide us with some guidelines in terms of the applicability of these protocols when operators plan to deploy their IMS/MMD networks. View full abstract»

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  • Evaluating the Benefits of Introducing PMIPv6 for Localized Mobility Management

    Publication Year: 2008 , Page(s): 74 - 80
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    Since recent years, it has been recognized that using global mobility protocol for managing localized mobility causes a number of problems, such as a long registration delay. To overcome these problems, proxy mobile IPv6 is proposed, which can avoid tunneling overhead over the air and support for hosts without an involvement in the mobility management. In this paper, we first discuss the recent localized mobility proposals and explore three major benefits that PMIPv6 can bring. In particular, we evaluate two aspects of the handover performance through a simple mathematical model for fast handovers for MIPv6, hierarchical MIPv6, fast handovers for HMIPv6 and PMIPv6. These analytical studies show that PMIPv6 may cause high handover latency if the local mobility anchor is located far from the current mobility access gateway. Therefore, some enhancements for PMIPv6 are suggested to further reduce the handover latency. The analysis ascertains that F-PMIPv6 is a promising mobility scheme to efficiently manage the localized mobility. View full abstract»

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  • A Hierarchical Route Optimization Scheme for Next Generation Mobile Network

    Publication Year: 2008 , Page(s): 81 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    A hierarchical route optimization scheme for next generation mobile network (HROS) is proposed to solve mobility management and route optimization problems. HROS integrates NBS and MAP to construct a hierarchical mobile network, MN's registration cost is reduced with regional management. Moreover, a route optimization scheme based on MAP is also introduced by HROS to eliminate pinball routing within mobile network. View full abstract»

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  • Secure Network Configuration and Route Discovery for Hybrid Mobile Ad Hoc Networks

    Publication Year: 2008 , Page(s): 86 - 91
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB) |  | HTML iconHTML  

    This paper provides a novel security solution for hybrid mobile ad hoc networks. The solution relies on secure network configuration, which is based on the use of preconfigured self-certifying identifiers stored into a portable memory device by a trusted party, to be attached with ad hoc network nodes. Mutual authentication is carried between the friendly neighbour nodes based on the self-certifying identifiers, resulting a safe subnetwork inside the local ad hoc network. The route discovery is carried only in the safe subnetwork through trusted nodes, and therefore the route found always goes only via trusted nodes. The provided solution is realized as secure ad hoc routing protocol (SARP), which is evaluated in a laboratory environment using an ad hoc network consisting of 11 nodes with/without connection to static networks. The evaluations indicate sensible level of delays and performance even if security is taken on board. View full abstract»

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  • Modeling and Analysis of a Self-Learning Worm Based on Good Point Set Scanning

    Publication Year: 2008 , Page(s): 92 - 97
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (166 KB) |  | HTML iconHTML  

    In order to speed up the propagating process, the worms need to scan many IP addresses to target vulnerable hosts. However, the distribution of IP addresses is highly nonuniform, which results in many scans wasted on invulnerable addresses. Inspired by the theory of good point set, this paper proposes a new scanning strategy, referred to as good point set scanning (GPSS), for worms. Experimental results show that GPSS can generate more distinct IP addresses and less unused IP addresses than the permutation scanning. Combined with group distribution, a static optimal GPSS is derived. Since the information can not be easily collected before a worm is released, a self-learning worm with GPSS is designed. Such worm can accurately estimate the underlying vulnerable-host distribution when a sufficient number of IP addresses of infected hosts are collected. We use a modified Analytical Active Worm Propagation (AAWP) to simulate data of Code Red and the performance of different scanning strategies. Experimental results show that once the distribution of vulnerable hosts is accurately estimated, a self- learning worm can propagate much faster than other worms. View full abstract»

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  • Analysis of the Cost/Performance Tradeoffs of SSL Acceleration

    Publication Year: 2008 , Page(s): 98 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    Business-to-business (B2B) and Business-to-consumer (B2C) transactions in public domains such as Internet require secure communications mechanisms and, especially for applications accessible through web browsers, the secure socket layer (SSL) protocol is one of the most viable solutions to provide the required level of confidentiality, message integrity and endpoint authentication. The two main alternatives for providing SSL security are the end-to-end and the accelerated architectural solutions, which enable different cost-performance tradeoffs, where performance is intended as the overall delay that the customer experiences to complete the transaction. In this paper, we provide an analytical model for the computation of performance and cost of both the end-to-end and of the accelerated SSL system architectures. In this way, the designer is provided with a tool for the identification of the most economic system configuration providing the desired performance level. View full abstract»

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  • On Detecting Port Scanning using Fuzzy Based Intrusion Detection System

    Publication Year: 2008 , Page(s): 105 - 110
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (237 KB) |  | HTML iconHTML  

    Intrusion detection is a mechanism used to detect various attacks on a wired or wireless network. Port scanning is one of the dangerous attacks that intrusion detection tries to detect. Snort, a famous network intrusion detection system (NIDS), detects a port scanning attack by combining and analyzing various traffic parameters. Because these parameters cannot be easily combined using a mathematical formula, fuzzy logic can be used to combine them; fuzzy logic can also reduce the number of false alarms. This paper presents a novel approach, based on fuzzy logic, to detect port scanning attacks. A fuzzy logic controller is designed and integrated with Snort in order to enhance the functionality of port scanning detection. Experiments are carried out in both wired and wireless networks. The results show that applying fuzzy logic adds to the accuracy of determining bad traffic. Moreover, it gives a level of degree for each type of port scanning attack. View full abstract»

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  • Cross-Layer Transmission Scheme with QoS Considerations for Wireless Mesh Networks

    Publication Year: 2008 , Page(s): 111 - 116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (315 KB) |  | HTML iconHTML  

    IEEE 802.11 wireless networks utilizes a hard handoff scheme when a station is travelling from one area of coverage to another one within a transmission duration. In IEEE 802.11s wireless mesh networks, the handoff procedure the transmitted data will first be buffered in the source MAP and be not relayed to the target MAP until the handoff procedure is finished. Besides, there are multi-hop in the path between the source station and the destination station. In each pair of neighboring MAPs, contention is needed to transmit data. The latency for successfully transmitting data is seriously lengthened so that the deadlines of data frames are missed with high probabilities. In this paper, we propose a cross-layer transmission (CLT) scheme with QoS considerations for IEEE 802.11 mesh wireless networks. By utilizing CLT, the ratios of missing deadlines will be significantly improved to conform strict time requirements for real-time multimedia applications. We develop a simulation model to investigate the performance of CLT. The capability of the proposed scheme is evaluated by a series of experiments, for which we have encouraging results. View full abstract»

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  • Construction of a Low Energy Cost Power Spanner for Wireless Ad hoc Networks

    Publication Year: 2008 , Page(s): 117 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB) |  | HTML iconHTML  

    Topology control in ad-hoc networks tries to lower node energy consumption by reducing transmission power and by confining interference, collisions and consequently retransmissions. In other words, we are given the communication graph G obtained when all the nodes transmit at maximum power, the goal is to identify a sparse subgraph G (also called power spanner) of G such that only energy-efficient links are retained in G . To achieve this goal, other desirable features of subgraph G have been identified. Having an upper bound on the maximum node degree of G is desirable to avoid bottlenecks in the Communication graph. We design algorithms that, given a unit-disc graph (UDG) G representing all feasible links, find a sparse subgraph G having maximum degree six and having minimum stretch factor. We propose method combining several well-known proximity graphs including Gabriel graph, Yao graph and LDS. We will show our algorithm (LECS) has low energy cost and small interference, compared with other known structures used in wireless ad hoc networks. View full abstract»

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  • Tier Based Anycast to Achieve Maximum Lifetime by Duty Cycle Control in Wireless Sensor Networks

    Publication Year: 2008 , Page(s): 123 - 128
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (438 KB) |  | HTML iconHTML  

    In a wireless sensor network, the routing control overhead is prohibitive because mostly many nodes are involved in routing. To overcome the overhead problem, tier based anycast protocol was proposed in (Kulkarni et al., 2006). However, it has a shortcoming of using much more energy compared to other competitors of deterministic routing protocols in transmitting data packets towards the sink node. In this paper, we visited the tier based anycast protocol in depth and presented a new analytic framework by using the concept of sub-tiering. Firstly, we formulated the problem for finding an optimal duty cycle for each tier as a minimax optimization problem, and proved that the solution exists and it is unique. From the analysis results, we found that the network lifetime can be improved very much by allocating a duty cycle adaptively for each tier. Through simulations, we also confirmed that our duty cycle control algorithm increases the network lifetime by approximately 30%. View full abstract»

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  • Congestion Avoidance Routing Protocol for QoS-Aware MANETs

    Publication Year: 2008 , Page(s): 129 - 134
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1091 KB) |  | HTML iconHTML  

    With the increase of multimedia traffic over the past few years and traffic differentiation introduced by IEEE 802.11e, nodes with delay-sensitive multimedia traffic tend to be busy for long periods, thus exacerbating the congestion problem in mobile ad hoc networks (MANETs). Although most of the existing routing protocols are based on the shortest path algorithm, some other metrics like load and delay have also been considered in some other research. In this paper, we first expose that the performance of MANETs routing protocols is highly dependent on the type of traffic generated or routed by intermediate nodes. This paper proposes a Type of service aware routing protocol (TSA), an enhancement to AODV, which uses both the ToS and traditional hop count as route selection metrics. TSA avoids congestion by distributing the load over a potentially greater area and therefore improving spatial reuse. Our simulation study reveals that TSA considerably improves the throughput and packet delay of both low and high priority traffic under different network operational conditions. View full abstract»

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  • Energy Efficient Topology Control Algorithm for Wireless Mesh Networks

    Publication Year: 2008 , Page(s): 135 - 140
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (230 KB) |  | HTML iconHTML  

    The control of the topology of a network makes it possible for the network nodes to reduce their power of transmission while ensuring that network connectivity is preserved. This paper explains the need for energy consumption control in Wireless Mesh Networks (WMNs) and proposes a Local Minimum Shortest-Path Tree (LM-SPT) algorithm for topology control for the WMNs. The algorithm is distributed with each node using only the information gathered locally to determine its own transmission power. The implementation is done in two phases. The construction of a minimum local shortest-path tree is first done. The removal of all unidirectional links is then done. The performance of the algorithm is demonstrated via several simulation tests. The resultant network topology preserves network connectivity in addition to possessing other desirable features such as: (1) reduction in the average node degree, (2) evenly distributed power consumption among the nodes as well as (3) a reduced total power consumption leading to longer connectivity periods. View full abstract»

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  • QoS Aware Dynamic Resource Allocation in Multiuser OFDM Systems with Priority for Different Services

    Publication Year: 2008 , Page(s): 141 - 146
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (326 KB) |  | HTML iconHTML  

    In this paper, we propose an algorithm for dynamic resource allocation in OFDM (orthogonal frequency division multiplexing) or OFDMA (OFD multiple access) based networks. We consider two groups of users consisting of group 1 called constant bit-rate (CBR) users (who are delay-sensitive and data-rate sensitive) and group 2 called best effort (BE) users. The proposed algorithm gives higher priority to the first group at the time of resource (transmitted power levels and subchannels) allocation to each user, to meet their CBR requirements. The performance of the proposed algorithm is evaluated through computer simulations, which show that the algorithm performs near optimum with the added superiority of meeting the bit requirements of the first group users. View full abstract»

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