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Selected Areas in Communications, IEEE Journal on

Issue 4 • Date May 2012

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Displaying Results 1 - 22 of 22
  • Table of contents

    Publication Year: 2012 , Page(s): c1 - c4
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  • [Staff list]

    Publication Year: 2012 , Page(s): c2
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  • Guest Editorial Broadband Wireless Communications for High Speed Vehicles

    Publication Year: 2012 , Page(s): 673 - 674
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (897 KB) |  | HTML iconHTML  

    The 15 papers in this special issue are divided into four categories: challenges in broadband wireless communications; physical layer techniques; radio resource management techniques; and field measurement and channel modeling. View full abstract»

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  • Distributed Antenna Systems for Mobile Communications in High Speed Trains

    Publication Year: 2012 , Page(s): 675 - 683
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB) |  | HTML iconHTML  

    With the deployment of high speed train (HST) systems increasing worldwide and their popularity with travelers growing, providing broadband wireless communications (BWC) in HSTs is becoming crucial. In this paper, a tutorial is presented on recent research into BWC provision for HSTs. The basic HST BWC network architecture is described. Two potential cellular architectures, microcells and distributed antenna systems (DASs) based cells, are introduced. In particular, the DAS is discussed in conjunction with radio over fiber (RoF) technology for BWC for HSTs. The technical challenges in providing DAS-based BWC for HSTs, such as handoff and RoF are discussed and outlined. View full abstract»

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  • OFDM Signal Detection in Doubly Selective Channels with Blockwise Whitening of Residual Intercarrier Interference and Noise

    Publication Year: 2012 , Page(s): 684 - 694
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (731 KB) |  | HTML iconHTML  

    Orthogonal frequency-division multiplexing (OFDM) is a popular broadband wireless transmission technique, but its performance can suffer severely from the intercarrier interference (ICI) induced by fast channel variation arising from high-speed motion. Existing ICI countermeasures usually address a few dominant ICI terms only and treat the residual similar to white noise. We show that the residual ICI has high normalized autocorrelation and that this normalized autocorrelation is insensitive to the multipath channel profile as well as a variety of other system and channel conditions. Consequently, the residual ICI plus noise can be whitened in a nearly channel-independent manner, leading to significantly improved detection performance. Simulation results confirm the theoretical analysis. In particular, they show that the proposed technique can significantly lower the ICI-induced error floor in maximum-likelihood sequence estimation (MLSE) designed to address a few dominant ICI terms. View full abstract»

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  • Time-Frequency Training OFDM with High Spectral Efficiency and Reliable Performance in High Speed Environments

    Publication Year: 2012 , Page(s): 695 - 707
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (559 KB) |  | HTML iconHTML  

    Orthogonal frequency division multiplexing (OFDM) is widely recognized as the key technology for the next generation broadband wireless communication (BWC) systems. Besides high spectral efficiency, reliable performance over fast fading channels is becoming more and more important for OFDM-based BWC systems, especially when high speed cars, trains and subways are playing an increasingly indispensable role in our daily life. The time domain synchronous OFDM (TDS-OFDM) has higher spectral efficiency than the standard cyclic prefix OFDM (CP-OFDM), but suffers from severe performance loss over high speed mobile channels since the required iterative interference cancellation between the training sequence (TS) and the OFDM data block. In this paper, a fundamentally distinct OFDM-based transmission scheme called time-frequency training OFDM (TFT-OFDM) is proposed, whereby every TFT-OFDM symbol has training information both in the time and frequency domains. Unlike TDS-OFDM or CP-OFDM where the channel estimation is solely dependent on either time-domain TS or frequency-domain pilots, the joint time-frequency channel estimation for TFT-OFDM utilizes the time-domain TS without interference cancellation to merely acquire the path delay information of the channel, while the path coefficients are estimated by using the frequency-domain grouped pilots. The redundant grouped pilots only occupy about 3% of the total subcarriers, thus TFT-OFDM still has much higher spectral efficiency than CP-OFDM by about 8.5% in typical applications. Simulation results also demonstrate that TFT-OFDM outperforms CP-OFDM and TDS-OFDM in high speed mobile environments. View full abstract»

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  • Seamless Dual-Link Handover Scheme in Broadband Wireless Communication Systems for High-Speed Rail

    Publication Year: 2012 , Page(s): 708 - 718
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1465 KB) |  | HTML iconHTML  

    Due to frequent handovers in broadband wireless communications in high-speed rail, communication interruption during handover could seriously degrade the experiences of passengers on the train. Aiming to reduce the interruption time, this paper proposes a seamless handover scheme based on a dual-layer and dual-link system architecture, where a Train Relay Station is employed to execute handover for all users in a train and two antennas are mounted at the front and rear of a train. In the proposed scheme, the front antenna executes handover while the rear antenna is still communicating with BS, so that the communication can keep non-interruptive throughout the handover. Moreover, bi-casting is adopted to eliminate the data forwarding delay between the serving BS and target BS. A complete handover protocol is designed and the performance of the proposed scheme is analyzed. It can be seen from analytical results that the handover failure probability decreases as cell overlap increases and the communication interruption probability decreases with the decrease of train handover location and the increase of cell overlap. The simulation results show that in the proposed scheme, the communication interruption probability is smaller than 1% when the handover location is properly selected and the system throughput is not affected by handover. In conclusion, both theoretical and simulation results show that the proposed scheme can efficiently perform seamless handover for high-speed rail with low implementation overhead. View full abstract»

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  • Cross-Layer Handoff Design in MIMO-Enabled WLANs for Communication-Based Train Control (CBTC) Systems

    Publication Year: 2012 , Page(s): 719 - 728
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1053 KB) |  | HTML iconHTML  

    Communication-Based Train Control (CBTC) system is an automated train control system using bidirectional train-ground communications to ensure the safe operation of rail vehicles. Handoff design has significant impacts on the train control performance in CBTC systems based on multi-input and multi-output (MIMO)-enabled WLANs. Most of previous works use traditional design criteria, such as network capacity and communication latency, in handoff designs. However, these designs do not necessarily benefit the train control performance. In this paper, we take an integrated design approach to jointly optimize handoff decisions and physical layer parameters to improve the train control performance in CBTC systems. We use linear quadratic cost for the train controller as the performance measure. The handoff decision and physical layer parameters adaptation problem is formulated as a stochastic control process. Simulation result shows that the proposed approach can significantly improve the control performance in CBTC systems. View full abstract»

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  • Seamless Wireless Connectivity for Multimedia Services in High Speed Trains

    Publication Year: 2012 , Page(s): 729 - 739
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1614 KB) |  | HTML iconHTML  

    The recent advent of high speed trains introduces new mobility patterns in wireless environments. The LTE-A (Long Term Evolution of 3GPP - Advanced) networks have largely tackled the Doppler effect problem in the physical layer and are able to keep wireless service with 100Mpbs throughput within a cell in speeds up to 350 km/h. Yet the much more frequent handovers across cells greatly increases the possibility of service interruptions, and the problem is prominent for multimedia communications that demand both high-throughput and continuous connections. In this paper, we present a novel LTE-based solution to support high throughput and continuous multimedia services for high speed train passengers. Our solution is based on a Cell Array that smartly organizes the cells along a railway, together with a femto cell service that aggregates traffic demands within individual train cabins. Given that the movement direction and speed of a high-speed train are generally known, our Cell Array effectively predicts the upcoming LTE cells in service, and enables a seamless handover that will not interrupt multimedia streams. To accommodate the extreme channel variations, we further propose a scheduling and resource allocation mechanism to maximize the service rate based on periodical signal quality changes. Our simulation under diverse network and railway/train configurations demonstrates that the proposed solution achieves much lower handover latency and higher data throughput, as compared to existing solutions. It also well resists to network and traffic dynamics, thus enabling uninterrupted quality multimedia services for passengers in high speed trains. View full abstract»

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  • Multi-Hop Connectivity Probability in Infrastructure-Based Vehicular Networks

    Publication Year: 2012 , Page(s): 740 - 747
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (378 KB) |  | HTML iconHTML  

    Infrastructure-based vehicular networks (consisting of a group of Base Stations (BSs) along the road) will be widely deployed to support Wireless Access in Vehicular Environment (WAVE) and a series of safety and non-safety related applications and services for vehicles on the road. As an important measure of user satisfaction level, uplink connectivity probability is defined as the probability that messages from vehicles can be received by the infrastructure (i.e., BSs) through multi-hop paths. While on the system side, downlink connectivity probability is defined as the probability that messages can be broadcasted from BSs to all vehicles through multi-hop paths, which indicates service coverage performance of a vehicular network. This paper proposes an analytical model to predict both uplink and downlink connectivity probabilities. Our analytical results, validated by simulations and experiments, reveal the trade-off between these two key performance metrics and the important system parameters, such as BS and vehicle densities, radio coverage (or transmission power), and maximum number of hops. This insightful knowledge enables vehicular network engineers and operators to effectively achieve high user satisfaction and good service coverage, with necessary deployment of BSs along the road according to traffic density, user requirements and service types. View full abstract»

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  • Radio Resource Allocation for OFDMA Systems in High Speed Environments

    Publication Year: 2012 , Page(s): 748 - 759
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (443 KB) |  | HTML iconHTML  

    In high speed train (HST) system, real-time multimedia entertainments are very important applications in which a data stream often contains packets with different quality of service requirements. For example, video stream encoded with scalability contains the base layer packets with high quality (HQ) bit error rate (BER) requirement and enhancement layers' packets with low quality (LQ) BER requirement. When a conventional allocation approach, which only considers one BER constraint for one data stream, is applied to orthogonal frequency division multiple access (OFDMA) systems, the BER constraint will be the strictest one among multiple requirements from different types of packets, which leads to inefficient allocation when each data stream has multiple BER requirements. This paper aims to develop novel resource allocation approach by considering multiple BER requirements for different types of packets in one data stream. In order to not only simplify the resource allocation, but also to compensate for the channel estimation error caused by Doppler shift in the HST environment, a proper number of contiguous subcarriers are grouped into chunks and spectrum is allocated chunk by chunk. Simulation results show that the developed resource allocation scheme outperforms the conventional scheme, particularly when the BER ratio of HQ packets to LQ packets is larger than one. Furthermore, in order to reduce the complexity of resource allocation further, an empirical allocation scheme is proposed to allocate better chunks to HQ packets. It is shown that the performance of the empirical allocation scheme is quite close to that of the optimal scheme. View full abstract»

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  • Cooperative Communication Aware Link Scheduling for Cognitive Vehicular Networks

    Publication Year: 2012 , Page(s): 760 - 768
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (457 KB) |  | HTML iconHTML  

    Throughput maximization is a key challenge for wireless applications in cognitive Vehicular Ad-hoc Networks (C-VANETs). As a potential solution, cooperative communications, which may increase link capacity by exploiting spatial diversity, has attracted a lot of attention in recent years. However, if link scheduling is considered, this transmission mode may perform worse than direct transmission in terms of end-to-end throughput. In this paper, we propose a cooperative communication aware link scheduling scheme and investigate the throughput maximization problem in C-VANETs. Regarding the features of cooperative communications and the availability of licensed spectrum, we extend the links into cooperative links/general links, define extended link-band pairs, and form a 3-dimensional (3-D) cooperative conflict graph to characterize the conflict relationship among those pairs. Given all cooperative independent sets in this graph, we mathematically formulate an end-to-end throughput maximization problem and near-optimally solve it by linear programming. Due to the NP-completeness of finding all independent sets, we also develop a heuristic pruning algorithm for cooperative communication aware link scheduling. Our simulation results show that the proposed scheme is effective in increasing end-to-end throughput for the session in C-VANETs. View full abstract»

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  • Efficient Data Dissemination in Vehicular Ad Hoc Networks

    Publication Year: 2012 , Page(s): 769 - 779
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB) |  | HTML iconHTML  

    Data services for in-vehicle consumption are expected to become a primary driver in the development of future vehicular networks. Due to download rate limitations of present wide-area cellular connectivity such as 3G (the likely `pipe' to/from vehicles for long range connectivity), direct peer-to-peer data sharing among vehicles can supplement vertical downloading with horizontal dissemination. This paper studies the inter-vehicle data dissemination problem based on a WAVE/802.11p vehicular ad hoc network, using network coding. We first derive the probability mass functions (PMFs) of dissemination completion time in a prototypical three-node case for both random broadcast and with network coding, to quantify the benefits of the latter. For a one dimensional (1-D) infinite lattice network, we next provide analytical results for the steady state dissemination velocity of a data set, using network coding. The gains from such network coding, relative to the baseline scheme of random broadcast, and with perfect feedback, in presence of Rayleigh fading wireless links for this network are estimated using simulations. View full abstract»

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  • Efficient On-Demand Data Service Delivery to High-Speed Trains in Cellular/Infostation Integrated Networks

    Publication Year: 2012 , Page(s): 780 - 791
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (602 KB) |  | HTML iconHTML  

    In this paper, we investigate on-demand data services for high-speed trains via a cellular/infostation integrated network. Service requests and acknowledgements are sent through the cellular network to a content server, while data delivery is achieved via trackside infostations. The optimal resource allocation problem is formulated by taking account of the intermittent network connectivity and multi-service demands. In order to achieve efficient resource allocation with low computational complexity, the original problem is transformed into a single-machine preemptive scheduling problem based on a time-capacity mapping. As the service demands are not known a priori, an online resource allocation algorithm based on Smith ratio and exponential capacity is proposed. The performance bound of the online algorithm is characterized based on the theory of sequencing and scheduling. If the link from the backbone network to an infostation is a bottleneck, a service pre-downloading algorithm is also proposed to facilitate the resource allocation. The performance of the proposed algorithms is evaluated based on a real high-speed train schedule. Compared with the existing approaches, our proposed algorithms can significantly improve the quality of on-demand data service provisioning over the trip of a train. View full abstract»

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  • DORA: Dynamic Optimal Random Access for Vehicle-to-Roadside Communications

    Publication Year: 2012 , Page(s): 792 - 803
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB) |  | HTML iconHTML  

    In this paper, we study random access in a drive-thru scenario, where roadside access points (APs) are installed on a highway to provide temporary Internet access for vehicles. We consider vehicle-to-roadside (V2R) communications for a vehicle that aims to upload a file when it is within the APs' coverage ranges, where both the channel contention level and transmission data rate vary over time. The vehicle will pay a fixed amount each time it tries to access the APs, and will incur a penalty if it cannot finish the file uploading when leaving the APs. First, we consider the problem of finding the optimal transmission policy with a single AP and random vehicular traffic arrivals. We formulate it as a finite-horizon sequential decision problem, solve it using dynamic programming (DP), and design a general dynamic optimal random access (DORA) algorithm. We derive the conditions under which the optimal transmission policy has a threshold structure, and propose a monotone DORA algorithm with a lower computational complexity for this special case. Next, we consider the problem of finding the optimal transmission policy with multiple APs and deterministic vehicular traffic arrivals thanks to perfect traffic estimation. We again obtain the optimal transmission policy using DP and propose a joint DORA algorithm. Simulation results based on a realistic vehicular traffic model show that our proposed algorithms achieve the minimal total cost and the highest upload ratio as compared with some other heuristic schemes. In particular, we show that the joint DORA scheme achieves an upload ratio 130% and 207% better than the heuristic schemes at low and high traffic densities, respectively. View full abstract»

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  • On Maximizing Delay-Constrained Coverage of Urban Vehicular Networks

    Publication Year: 2012 , Page(s): 804 - 817
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2934 KB) |  | HTML iconHTML  

    The success of a real-time sensing application with a vehicular network highly depends on the spatiotemporal coverage of sensing data that can be collected from the vehicular network. Deploying broadband wireless base stations is an effective way to collect vehicular sensing data and the deployment of base stations has a great impact on delay-constrained coverage. This paper considers the critical problem of base stations for maximizing delay-constrained coverage of an urban area achieved by the vehicular network. This is particularly challenging. We theoretically prove that the optimal deployment of base stations is NP-hard even when the future vehicular traces are assumed as a priori. In a realistic setting, however, the future vehicular traces cannot be known in advance. Therefore, the challenge is to incorporate high vehicle mobility and compute the base station deployment for maximizing the expected delay-constrained coverage. By mining a large dataset of real vehicular GPS traces, we show that there is strong regularity with vehicle mobility. With this important observation, we formulate a new objective of maximizing the expected sensing coverage. This takes random vehicle mobility into account and exploits the regularity in vehicle mobility. We develop greedy algorithms for base station deployment. The achieved sensing coverage of the proposed algorithm is guaranteed to be larger than (1-1/e) of the theoretical optimum. We have performed extensive simulations based on the real vehicular GPS trace dataset and conclusive results show that our algorithms achieve near optimal coverage of the urban area and significantly outperform alternative algorithms. View full abstract»

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  • Multicast Capacity for VANETs with Directional Antenna and Delay Constraint

    Publication Year: 2012 , Page(s): 818 - 833
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1306 KB) |  | HTML iconHTML  

    Vehicular Ad Hoc Networks (VANETs) with base stations are called hybrid VANET, where base stations are deployed to improve the throughput capacity. In this paper, we study the multicast throughput capacity for hybrid wireless VANET with a directional antenna on each vehicle and the end-to-end delay is constrained. In the hybrid VANET, there are n mobile vehicles (or nodes) distributed in a unit area with m strategically deployed base stations connected using high-bandwidth wire links. There are n_s multicast sessions and each multicast session has one source which transmits identical data to its associated p destinations. We investigate the multicast throughput capacity for two mobility models with two mobility scales, respectively, while each vehicular node is equipped with a directional antenna and with a tolerant delay D. That is, a source node transmits to its p destinations only with the help of normal nodes within D consecutive time slots. Otherwise, the transmission will be performed with in the infrastructure mode, i.e., with the help of base stations. We demonstrate that the one dimensional i.i.d. slow mobility pattern catch the main feature of VANETs. And we find that the multicast throughput capacity of the hybrid wireless VANET greatly depends on the delay constraint D, the number of base stations m, and the beamwidth of directional antenna θ. In the order of magnitude, we obtain the closed form of the multicast throughput capacity of the hybrid directional VANET, where the impact of D, m and θ on the multicast throughput capacity is analyzed. Moreover, we derive the lower bound of the muticast throughput using a similar raptor coding approach. View full abstract»

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  • Position-Based Modeling for Wireless Channel on High-Speed Railway under a Viaduct at 2.35 GHz

    Publication Year: 2012 , Page(s): 834 - 845
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4060 KB) |  | HTML iconHTML  

    This paper presents a novel and practical study on the position-based radio propagation channel for High-Speed Railway by performing extensive measurements at 2.35 GHz in China. The specification on the path loss model is developed. In particular, small scale fading properties such as K-factor, Doppler frequency feature and time delay spread are parameterized, which show dynamic variances depending on the train location and the transceiver separation. Finally, the statistical position-based channel models are firstly established to characterize the High-Speed Railway channel, which significantly promotes the evaluation and verification of wireless communications in relative scenarios. View full abstract»

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  • Correction to "Analysis and Optimization of Sleeping Mode in WiMAX via Stochastic Decomposition Techniques" [Sep 11 1630-1640]

    Publication Year: 2012 , Page(s): 846
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    This note is to correct the author list and authors' affiliations for the above listed paper (ibid., vol. 29, no. 8, pp. 1630-1640, Sep 2011). The acknowledgements are also revised. View full abstract»

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  • Call for papers

    Publication Year: 2012 , Page(s): 847
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    Freely Available from IEEE
  • Call for papers

    Publication Year: 2012 , Page(s): 848
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    Freely Available from IEEE
  • Staff list

    Publication Year: 2012 , Page(s): c3
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    Freely Available from IEEE

Aims & Scope

IEEE Journal on Selected Areas in Communications focuses on all telecommunications, including telephone, telegraphy, facsimile, and point-to-point television, by electromagnetic propagation.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Muriel Médard
MIT