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Wireless Communications, IEEE

Issue 5 • Date October 2006

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Displaying Results 1 - 20 of 20
  • IEEE Wireless Communications, Oct. 2006, Vol. 13 No. 5

    Page(s): c1
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    Freely Available from IEEE
  • Table of contents

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    Freely Available from IEEE
  • WHERE IS MOBILE AD HOC NETWORK HEADING?

    Page(s): 2 - 3
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  • WORLD RADIOCOMMUNICATION CONFERENCE AND ITS IMPACT ON WIRELESS TECHNOLOGY

    Page(s): 4 - 5
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    The International Union's World Radiocommunication Conference (WRC) is scheduled to convene in Geneva, Switzerland, on October 15, 2007. The first of such worldwide conferences since 2003, WRC '07 includes about 25 substantive items on the agenda dealing with possible changes to the Radio Regulations. A few of these items are briefly discussed to provide readers with a feel for the diversity of issues that come up at these conferences and their possible impacts on wireless technology View full abstract»

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  • SECURING VEHICULAR COMMUNICATIONS

    Page(s): 8 - 15
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    The road to a successful introduction of vehicular communications has to pass through the analysis of potential security threats and the design of a robust security architecture able to cope with these threats. In this article we undertake this challenge. In addition to providing a survey of related academic and industrial efforts, we also outline several open problems View full abstract»

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  • POSITION VERIFICATION APPROACHES FOR VEHICULAR AD HOC NETWORKS

    Page(s): 16 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (107 KB) |  | HTML iconHTML  

    Intervehicle communication is regarded as one of the major applications of mobile ad hoc networks (MANETs). Compared to MANETs, these so-called vehicular ad hoc networks (VANETs) have special requirements in terms of node mobility and position-dependent applications, which are well met by geographic routing protocols. Functional research on geographic routing has already reached a considerable level, whereas security aspects have been vastly neglected so far. Since position dissemination is crucial for geographic routing, forged position information has severe impact regarding both performance and security. In this work, we first analyze the problems that may arise from falsified position data. Then, in order to lessen these problems, we propose detection mechanisms that are capable of recognizing nodes cheating about their location in position beacons. In contrast to other position verification approaches, our solution does not rely on special hardware or dedicated infrastructure. Evaluation based on simulations shows that our position verification system successfully discloses nodes disseminating false positions and thereby widely prevents attacks using position cheating View full abstract»

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  • The scalability problem of vehicular ad hoc networks and how to solve it

    Page(s): 22 - 28
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    Intervehicle communication (IVC) and its diverse application possibilities are experiencing growing interest both in research and industry. The dissemination of active safety messages generated by context-sensitive applications in vehicular ad hoc networks (VANETs) promises to improve passenger safety and comfort. One of the main challenges inherent to the deployment of VANETs is operability, both in very sparse and in highly overloaded networks. This scalability problem is not comprehensively addressed by existing approaches, as they only focus on parts of the problem. This article shows how a relevance-based, altruistic communication scheme helps realize scalability by optimizing the application benefit and the bandwidth usage. In-vehicle and intervehicle message selection are based on a relevance function that makes use of the current context and the content of the messages. A novel, proprietary cross-layer architecture and an IEEE 802.11e-based architecture can be used to implement the scheme View full abstract»

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  • A survey and qualitative analysis of mac protocols for vehicular ad hoc networks

    Page(s): 30 - 35
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    In order to avoid transmission collisions in mobile ad hoc networks (MANETs), a reliable and efficient medium access control (MAC) protocol is needed. Vehicular MANETs (VANETs) have vehicles as network nodes and their main characteristics are high mobility and speed. Active safety applications for VANETs need to establish reliable communications with minimal transmission collisions. Only few MAC protocols designed for MANETs can be adapted to efficiently work in VANETs. In this article we provide a short overview on some MANET MAC protocols, and then we summarize and qualitatively compare the ones suited for VANETs View full abstract»

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  • Design of 5.9 ghz dsrc-based vehicular safety communication

    Page(s): 36 - 43
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    The automotive industry is moving aggressively in the direction of advanced active safety. Dedicated short-range communication (DSRC) is a key enabling technology for the next generation of communication-based safety applications. One aspect of vehicular safety communication is the routine broadcast of messages among all equipped vehicles. Therefore, channel congestion control and broadcast performance improvement are of particular concern and need to be addressed in the overall protocol design. Furthermore, the explicit multichannel nature of DSRC necessitates a concurrent multichannel operational scheme for safety and non-safety applications. This article provides an overview of DSRC based vehicular safety communications and proposes a coherent set of protocols to address these requirements View full abstract»

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  • Cluster-based multi-channel communications protocols in vehicle ad hoc networks

    Page(s): 44 - 51
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    The dedicated short range communications (DSRC) standard equipped with seven channels is designated for intelligent transportation system (ITS) applications to improve the driving safety and support networking services among moving vehicles. Making best use of the DSRC multichannel architecture, we propose a cluster-based multichannel communications scheme, which integrates the clustering with contention-free/contention-based MAC protocols. In our proposed scheme, the elected cluster-head (CH) vehicle functions as the coordinator (like WLAN's basestation) to collect/deliver the real-time safety messages within its own cluster and forward the consolidated safety messages to the neighboring CHs. Also, the CH vehicle controls channel-assignments for cluster-member vehicles transmitting/receiving the non-real-time traffics, which makes the wireless channels more efficiently utilized for the non-real-time data transmissions. Our scheme uses the contention-free MAC (TDMA/broadcast) within a cluster and the IEEE 802.11 MAC among CH vehicles such that the real-time delivery of safety messages can be guaranteed. The simulation results show that our proposed scheme can significantly improve the throughputs of vehicle data communications while guaranteeing the real-time delivery of safety messages View full abstract»

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  • Mobeyes: smart mobs for urban monitoring with a vehicular sensor network

    Page(s): 52 - 57
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    Vehicular sensor networks are emerging as a new network paradigm of primary relevance, especially for proactively gathering monitoring information in urban environments. Vehicles typically have no strict constraints on processing power and storage capabilities. They can sense events (e.g., imaging from streets), process sensed data (e.g., recognizing license plates), and route messages to other vehicles (e.g., diffusing relevant notification to drivers or police agents). In this novel and challenging mobile environment, sensors can generate a sheer amount of data, and traditional sensor network approaches for data reporting become unfeasible. This article proposes MobEyes, an efficient lightweight support for proactive urban monitoring based on the primary idea of exploiting vehicle mobility to opportunistically diffuse summaries about sensed data. The reported experimental/analytic results show that MobEyes can harvest summaries and build a low-cost distributed index with reasonable completeness, good scalability, and limited overhead View full abstract»

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  • High-throughput multiple-input multipleoutput systems for in-home multimedia streaming

    Page(s): 60 - 66
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB) |  | HTML iconHTML  

    Wireless communication systems based on multiple-input multiple-output (MIMO) technology have the potential to achieve increased spectral efficiency with no additional transmit power or bandwidth requirements. This can be achieved by exploiting the spatial subchannels between the multiple transmit and receive elements. The enhanced performance of MIMO technology makes it a strong candidate for ad hoc systems requiring very high throughput, such as high-definition multimedia streaming in the home. In this article we compare the performance of conventional and newly proposed MIMO architectures for such applications. Specifically designed antenna arrays are proposed as a solution to significantly reduced MIMO performance in line-of-sight (LoS) conditions. To help in the design of such systems, the criterion for achieving maximum MIMO capacity in LoS is presented as a function of the transmitter-to-receiver separation distance, the array orientation and the element spacings. The performance of the LoS-enhanced proposal and the conventional system is quantified in terms of the channel capacity, the packet error rate (PER) and the throughput by employing a MIMO-enabled WLAN physical layer simulator. The results from MIMO measurements performed inside an anechoic chamber and in an indoor environment are presented to validate the theoretic predictions View full abstract»

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  • QoS-aware TDMA for end-to-end traffic scheduling in ad hoc networks

    Page(s): 68 - 74
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    The proliferation of low-cost broadband air interfaces has paved the way to the introduction of high-definition multimedia services in mobile and wireless networks. The cost for network resources utilization, when provisioning such services, will play a prominent role in their commercial success, since the more spare resources that can be used, the more cheaply the services can be delivered to the end users. In the context of promoting the role of ad hoc networks as service platforms for high quality multimedia applications, this article first discusses and classifies a set of issues involved in quality of service (QoS) provisioning in ad hoc networks and then presents a congestion-free TDMA algorithm for end-to-end network resources assignment via an optimized mechanism that relies on capacity requests and grants. The article also illustrates a method for invoking this algorithm to achieve efficient end-to-end QoS provisioning and concludes by showing the superiority of the proposed algorithm, as compared to other recently proposed TDMA scheduling algorithms View full abstract»

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  • Codecast: a network-coding-based ad hoc multicast protocol

    Page(s): 76 - 81
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    In this article we present CodeCast, a network-coding-based ad hoc multicast protocol. CodeCast is especially well-suited for multimedia applications with low-loss, low-latency constraints such as audio/video streaming. The key ingredient of CodeCast is random network coding, which transparently implements both localized loss recovery and path diversity with very low overhead. Simulation results show that in a typical setting, CodeCast yields a nearly 100 percent delivery ratio, as compared to a 94 percent delivery ratio by traditional multicast. More importantly, the overhead is reduced by as much as 50 percent View full abstract»

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  • QoS guarantee and provisioning for realtime digital video over mobile ad hoc cdma networks with cross-layer design

    Page(s): 82 - 88
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    In this article we investigate the trade-offs and the constraints for multimedia over mobile ad hoc CDMA networks, and propose a cross-layer distributed power control and scheduling protocol to resolve those trade-offs and constraints in order to provide high-quality video over wireless ad hoc CDMA networks. In particular, a distributed power control and scheduling protocol is proposed to control the incurred delay of video streaming over multihop wireless ad hoc networks, as well as the multiple access interference (MAI). We also investigate the impacts of Doppler spread and noisy channel estimates upon the end-to-end video quality, and provide a relatively robust system which employs a combination of power control and coding/interleaving to combat the effects of Doppler spread by exploiting the increased time diversity when the Doppler spread becomes large. Thus, more robust end-to-end video quality can be achieved over a wide range of channel conditions View full abstract»

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  • Architecture for reliable service discovery and delivery in manets based on power management employing slp extensions

    Page(s): 90 - 95
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    Limited energy resources and mobility issues affect the topology of ad hoc networks and introduce difficulties in service discovery. The high possibility of a link breakdown due to low energy supplies in a ubiquitous computing environment, such as a mobile ad hoc network (MANET), raises service-provider selection issues with regard to achieving the best possible service reliability. Every node requiring a specific service must choose a provider under certain criteria. This article provides an overview of standardized service-discovery and delivery solutions. In addition, a novel architecture is proposed which provides the ability to select a service provider by taking into account metrics such as the power supplies of the service provider and concomitant path towards the destination. The proposed algorithm is decentralized and based on service location protocol version 2 (SLPvZ) extensions View full abstract»

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  • SVC-based multisource streaming for robust video transmission in mobile ad hoc networks

    Page(s): 96 - 103
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    Emerging noninfrastructure-based network types like mobile ad-hoc networks (MANETs) are becoming suitable platforms for exchanging/sharing real-time video streams, because of recent progress in routing algorithms, throughput and transmission bit-rate. MANETs are characterized by highly dynamic behavior of the transmission routes and path outage probabilities. In this article a multisource streaming approach is presented to increase the robustness of real-time video transmission in MANETs. For that, video coding as well as channel coding techniques on the application layer are introduced, exploiting the multisource representation of the transferred media. Source coding is based on the scalable video coding (SVC) extension of H.264/MPEG4-AVC with different layers for assigning importance for transmission. Channel coding is based on a novel unequal packet loss protection (UPLP) scheme, which is based on Raptor forward error correction (FEC) codes. While in the presented approach, the reception of a single stream guarantees base quality only, the combined reception enables playback of video at full quality and/or lower error rates. Furthermore, an application layer protocol is introduced for supporting peer-to-peer based multisource streaming in MANETs View full abstract»

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  • Information modeling and handling for context-aware multimedia services

    Page(s): 104 - 111
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    This article presents research challenges in wireless ad hoc networks supporting context-aware multimedia services from the point of view of different context-modeling approaches and a system architecture for context handling and delivery. Modeling techniques for context information are classified into six different categories and benchmarked according to their support with regard to 12 service requirements described in this work. One of these modeling techniques is used in the framework of a distributed context handling and delivery system that is also part of this article's contribution and a representative wireless ad hoc application scenario is presented. This end user scenario and many others are possible thanks to the flexibility and adaptability of the above mentioned context handling and delivery system View full abstract»

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Aims & Scope

IEEE Wireless Communications Magazine deals with all technical and policy issues related to personalization, location-independent communications in all media.

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Editor-in-Chief
Hsiao-Hwa Chen
Cheng Kung University, Taiwan