By Topic

Wireless Communications, IEEE

Issue 3 • Date June 2010

Filter Results

Displaying Results 1 - 16 of 16
  • IEEE Wireless Communications

    Page(s): c1
    Save to Project icon | Request Permissions | PDF file iconPDF (309 KB)  
    Freely Available from IEEE
  • Table of contents

    Page(s): 1
    Save to Project icon | Request Permissions | PDF file iconPDF (82 KB)  
    Freely Available from IEEE
  • Good cooperation demands good coordination: coordinated cooperative communications [Message from the Editor in Chief]

    Page(s): 2 - 3
    Save to Project icon | Request Permissions | PDF file iconPDF (408 KB)  
    Freely Available from IEEE
  • Smart grids for green communications [Industry Perspectives]

    Page(s): 4 - 6
    Save to Project icon | Request Permissions | PDF file iconPDF (584 KB)  
    Freely Available from IEEE
  • Scanning the literature

    Page(s): 8 - 9
    Save to Project icon | Request Permissions | PDF file iconPDF (907 KB)  
    Freely Available from IEEE
  • LTE-advanced: next-generation wireless broadband technology [Invited Paper]

    Page(s): 10 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    LTE Release 8 is one of the primary broadband technologies based on OFDM, which is currently being commercialized. LTE Release 8, which is mainly deployed in a macro/microcell layout, provides improved system capacity and coverage, high peak data rates, low latency, reduced operating costs, multi-antenna support, flexible bandwidth operation and seamless integration with existing systems. LTE-Advanced (also known as LTE Release 10) significantly enhances the existing LTE Release 8 and supports much higher peak rates, higher throughput and coverage, and lower latencies, resulting in a better user experience. Additionally, LTE Release 10 will support heterogeneous deployments where low-power nodes comprising picocells, femtocells, relays, remote radio heads, and so on are placed in a macrocell layout. The LTE-Advanced features enable one to meet or exceed IMT-Advanced requirements. It may also be noted that LTE Release 9 provides some minor enhancement to LTE Release 8 with respect to the air interface, and includes features like dual-layer beamforming and time-difference- of-arrival-based location techniques. In this article an overview of the techniques being considered for LTE Release 10 (aka LTEAdvanced) is discussed. This includes bandwidth extension via carrier aggregation to support deployment bandwidths up to 100 MHz, downlink spatial multiplexing including single-cell multi-user multiple-input multiple-output transmission and coordinated multi point transmission, uplink spatial multiplexing including extension to four-layer MIMO, and heterogeneous networks with emphasis on Type 1 and Type 2 relays. Finally, the performance of LTEAdvanced using IMT-A scenarios is presented and compared against IMT-A targets for full buffer and bursty traffic model. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Coordinated and distributed MIMO [Guest Editorial]

    Page(s): 24 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (294 KB) |  | HTML iconHTML  

    The impetus for this feature topic was spurred by the technical trend in wireless communications: the need for high bit rates (~1 Gb/s) in future wireless systems. However, due to the limited transmit power, the transmission distance cannot be long if the desired transmission rate is very high. In order to have a reasonable coverage area in each cell, antennas centrally attached to the base station in conventional mobile systems should be distributed through the entire cell via wires (or fibers) so that the wireless transmission distance between mobile units and base stations can be shortened. Moreover, reception of one signal at different locations provides spatial diversity against fading. Such network architecture is called a distributed antenna system (DAS). In order to reduce the transmission distance and provide diversity gain, the distributed multiple-input multiple-output (MIMO) concept is introduced to achieve broadband wireless transmission. In addition, coordination from multiple adjacent cells is needed to efficiently use the distributed MIMO. Therefore, coordinated and distributed MIMO becomes crucial. The key to implement coordinated and distributed MIMO is to have the mobiles communicate simultaneously with several remote antennas with perfect coordination between these antennas. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Coordinated multipoint transmission/reception techniques for LTE-advanced [Coordinated and Distributed MIMO]

    Page(s): 26 - 34
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (287 KB) |  | HTML iconHTML  

    This article presents an elaborate coordination technique among multiple cell sites called coordinated multipoint transmission and reception in the Third Generation Partnership Project for LTE-Advanced. After addressing major radio access techniques in the LTE Release 8 specifications, system requirements and applied radio access techniques that satisfy the requirements for LTE-Advanced are described including CoMP transmission and reception. Then CoMP transmission and reception schemes and the related radio interface, which were agreed upon or are currently being discussed in the 3GPP, are presented. Finally, system-level simulation evaluations show that the CoMP transmission and reception schemes have a significant effect in terms of improving the cell edge user throughput based on LTE-Advanced simulation conditions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cooperative distributed antenna systems for mobile communications [Coordinated and Distributed MIMO]

    Page(s): 35 - 43
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1263 KB) |  | HTML iconHTML  

    Cooperative distributed antenna systems have drawn considerable attention in recent years due to their potential to enhance both the coverage and the spectral efficiency of mobile communication systems. In this article the conceptual description of a cooperative DAS for mobile communications is presented together with key techniques for DASs, including distributed multiple- input multiple-output for single and multiple users, handover, and transmit power allocation. Furthermore, theoretical and simulation results on the spectral or transmit power efficiency of cooperative DASs are given and compared with those on conventional collocated antenna systems. It is shown that a cooperative DAS can provide very promising performance enhancements in capacity and transmit power efficiency. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Low-complexity resource allocation and its application to distributed antenna systems [Coordinated and Distributed MIMO]

    Page(s): 44 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (319 KB) |  | HTML iconHTML  

    The aim of this tutorial article is to present low-complexity resource allocation approaches that rely on chunks of subcarriers for downlink distributed antenna systems. The chunk-based resource allocation approach is first introduced for single-antenna base stations with the consideration of guaranteeing an average bit error rate constraint per chunk and is compared to subcarrier- based allocation. How it can be combined with maximal ratio transmission and zero-forcing beamforming for base stations with many antennas is then described. Finally, we discuss how the techniques can be applied to DASs. It is shown that in typical wireless environments chunkbased resource allocation coupled with MRT and ZFB in the DAS can reduce the complexity of resource allocation significantly at the cost of negligible performance loss compared to subcarrier- based allocation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of and compensation for non-ideal RoF links in DAS [Coordinated and Distributed MIMO]

    Page(s): 52 - 59
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    Distributed antenna systems have been found to be an elegant solution for the problems arising in high-data-rate wireless communication, particularly in large service areas. This article considers radio over fiber links as an essential part of the DAS, connecting the central unit with the remote antenna units. In particular, we analyze and discuss delays and nonlinearities stemming from the RoF links. In addition, we study the compensation for these impairments. Our studies indicate that the RoF links are a viable and cost-effective solution for implementing the DAS, although some of the RoF link non-idealities require compensation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cooperative communications based on rateless network coding in distributed MIMO systems [Coordinated and Distributed MIMO]

    Page(s): 60 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (446 KB) |  | HTML iconHTML  

    In cellular distributed antenna systems, cooperation among base stations or remote antenna units to exploit multiple-input multiple-output gains could mitigate interference as well as provide more spatial diversity, which could significantly improve overall spectrum efficiency. However, most existing cooperation schemes require perfect synchronization, which is difficult and even impossible in practical distributed multi-user systems. When synchronization is not perfect, cooperative communication performance severely degrades. Orthogonal channel assignment among collaborating stations with rateless network coding allows synchronization to be performed independently, and provides a coding scheme with close-to-capacity performance. In this article we discuss how to construct cooperative communication schemes based on rateless network coding in distributed MIMO systems. Specifically, we propose two cooperation strategies: single-source cooperation based on rateless coding and multisource cooperation based on rateless network coding. The proposed cooperative strategies are applicable to both uplink cooperation among users and downlink cooperation among BSs or RAUs in cellular DASs, providing a parameter-flexible, encodingsimple, and bandwidth-efficient cooperative solution. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed antenna system capacity scaling [Coordinated and Distributed MIMO]

    Page(s): 68 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (333 KB) |  | HTML iconHTML  

    The distributed antenna system concept promises to enhance the capacity and diversity of next-generation wireless communication networks, due to the inherently added micro and macro diversity. In this article we first give an overview of the main benefits of a DAS in relation to a collocated antenna system. Next we study the sum-capacity scaling of a multi-user DAS with the number of jointly processed transmit antennas in the downlink. In a practical system this scaling will have implications on the number of antennas worth jointly processing, since the costs of processing an additional antenna can be higher than the additional benefits obtained. Results show that the most important system property to attain the highest capacity gains is symmetry, and the users that attain the maximum gain are those at cell borders. They also confirm that the main DAS feature that makes possible its gains over the CAS architecture are the additional degrees of freedom/diversity provided by such an architecture, which increase the probability of finding a system state with high symmetry and of each user being near one of the transmit antennas. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Exploring multiple radios and multiple channels in wireless mesh networks [Accepted from Open Call]

    Page(s): 76 - 85
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    Much research has been performed investigating the challenging issue of efficiently utilizing the network-wide capacity available in the multihop wireless mesh networks with multiple radios and multiple channels. In this work, multihop routing and channel assignment are intertwined issues. In this article we present summaries of this work based on two broad categorizations in terms of algorithm features: centralized and distributed approaches. Due to the multiple dimensions of the topics, we subgroup the papers in terms of how the interactions between routing and channel assignments are treated. They include channel assignment based on the given connectivity graph, joint design of routing and channel assignment, routing with localized considerations on channel selection, and channel assignment with local channel usage and traffic load information. With the centralized approach, the schemes are able to target optimal channel assignment and joint design on both channel assignment and routing issues. In the distributed approach, the papers take steps focused on either route metrics or channel scheduling based on localized information about the links at each node. Comparisons and open research issues are given as the conclusion. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Applications of the cross-layer paradigm for improving the performance of WiMax [Accepted from Open Call]

    Page(s): 86 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (309 KB) |  | HTML iconHTML  

    IEEE 802.16 WiMAX is anticipated to operate across diverse and formidable circumstances under stringent performance requirements such as reduced delay, jitter, and dropped packets while providing high network utilization. As a potential remedy to alleviate these performance challenges, cross-layer design and optimization beyond layered architecture have been envisioned as in many similar communication systems. In this article some recent cross-layer design and solutions for improving the performance of IEEE 802.16 WiMAX are described. Moreover, a novel routing-scheduling scheme to illustrate the application and realization of the cross-layer paradigm in this domain is presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • CORE: a coding-aware opportunistic routing mechanism for wireless mesh networks [Accepted from Open Call]

    Page(s): 96 - 103
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    Opportunistic routing is a new routing paradigm that takes advantage of the broadcast characteristic of a wireless channel for data delivery in a wireless mesh network. Network coding has recently emerged as a new coding paradigm that can significantly improve the throughput performance of a WMN. In this article we explore the combination of opportunistic routing and network coding for improving the performance of a WMN. We first review existing opportunistic routing and coding-aware routing protocols, respectively, classify these protocols based on different criteria, and discuss their merits and drawbacks. We then propose a coding- aware opportunistic routing mechanism that combines hop-by-hop opportunistic forwarding and localized inter-flow network coding for improving the throughput performance of a WMN. Through opportunistic forwarding, CORE allows the next-hop node with the most coding gain to continue the packet forwarding. Through localized network coding, CORE attempts to maximize the number of packets that can be carried in a single transmission. Simulation results show that CORE can significantly improve the throughput performance of a WMN as compared with existing protocols. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

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

Full Aims & Scope

Meet Our Editors

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