DOCSLIB.ORG

Cooperative Communication Techniques in Wireless Networks (Analysis with Variable Relay Positioning)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cooperative Communication Techniques in Wireless Networks (Analysis with Variable Relay Positioning) MEE10:97 COOPERATIVE COMMUNICATION TECHNIQUES IN WIRELESS NETWORKS (ANALYSIS WITH VARIABLE RELAY POSITIONING) Danna Nigatu Mitiku Onwuli Chinedu Lawrence This thesis is presented as part of the Degree of Master of Science in Electrical Engineering Blekinge Institute of Technology October 2010 Blekinge Institute of Technology School of Engineering Supervisor: Prof. Abbas Mohammed Examiner: Prof. Abbas Mohammed ** This page is left blank intentionally** Abstract Signal transmission in Wireless Networks suffers considerably from many impairments, one of which is channel fading due to multipath propagation. Cooperative Communication is a technique which could be employed to mitigate the effects of channel fading by exploiting diversity gain achieved via cooperation between nodes and relays. To achieve transmit diversity, a node would generally require more than one transmitting antenna which is not too common due to the limits in size and complexity of wireless mobile devices. However by sharing antennas with other single-antenna nodes in a multi-user environment, a virtual multi-antenna array is formed and transmit-diversity is accomplished. Subsequently, radio coverage is extended without the need to implement multiple antennas on nodes and increased transmission reliability is achieved. In this scenario, a network containing a sender, a destination and a relay is analyzed. Two cooperative communication schemes which include Amplify and forward and Decode and forward are employed with different combining techniques are investigated and results obtained from simulations with respect to variable relay positioning are presented. Keywords: Amplify-and-Forward, Bit-Error-Rate, Cooperative Communications, Decode and Forward, Performance Analysis, Signal-to-Noise-Ratio, Wireless Networks. ** This page is left blank intentionally** Acknowledgments My heartfelt gratitude goes to God for his help and guidance in my daily undertakings and also my studies in Sweden. Also not forgetting a father and a teacher, Professor Abbas Mohammed, who in every way offered his assistance and support. I deeply appreciate your thorough guidance and supervision to the thesis work. Thank you so much. Many thanks to my parents Mihiret Seta and Mitiku Danna, my brothers and sisters, especially Liyuwork Mitiku, for their unparalleled support all through the years in my life. You are my rock. I extend my profound gratitude to the entire staff at Blekinge Institute of Technology, especially Mikael Åsman, for their kind endeavours and support. Finally, a big thank you to my classmates and friends, especially Esayas Getachew and Ermias Shibiru. I appreciate your friendship and the impact we had on each other – you all put the colours in my life. Nigatu M. Danna My gratitude and praise goes to God for his mercies and love in guiding and leading me to realise my goals. I would remain ever faithful in praise and worship. I would also like to extend my warmest thanks to Professor Abbas Mohammed at Blekinge Institute of Technology for his supervision and support towards my thesis work. He was a real teacher and a father. Finally a big thank you to my family and friends for their invaluable encouragement and support all the way. Love you all. Onwuli C. Lawrence Table of Contents List of Figures ............................................................................................................................ i List of Symbols and Abbreviations .......................................................................................... iii CHAPTER 1 ............................................................................................................................ 1 Introduction ............................................................................................................................... 1 1.1 Introduction .................................................................................................................. 1 1.2 Thesis Overview .......................................................................................................... 3 CHAPTER 2 ............................................................................................................................ 4 Wireless Communications ........................................................................................................ 4 2.1 Introduction .................................................................................................................. 4 2.1.1 Bit-Error-Rate (BER) ............................................................................................. 4 2.1.2 Signal-to-Noise-Ratio (SNR) ................................................................................. 5 2.2 Channel Impairments ................................................................................................... 5 2.2.1 Path Loss ................................................................................................................ 5 2.2.2 Free Space Path Loss ............................................................................................. 6 2.2.3 Noise ...................................................................................................................... 7 2.2.4 Inter-Symbol Inteference ....................................................................................... 9 2.2.5 Fading .................................................................................................................. 10 2.2.6 Multipath Fading .................................................................................................. 10 2.2.7 Communication Channels .................................................................................... 13 2.3 Error Compensation Techniques ................................................................................ 14 2.3.1 Forward Error Correction .................................................................................... 14 2.3.2 Adaptive Equalization .......................................................................................... 15 2.3.3 Diversity ............................................................................................................... 16 2.4 Diversity Techniques ................................................................................................. 16 2.4.1 Space Diversity .................................................................................................... 16 2.4.2 Frequency Diversity ............................................................................................. 17 2.4.3 Time Diversity ..................................................................................................... 18 2.4.4 Polarization Diversity .......................................................................................... 18 2.4.5 Multiuser Diversity .............................................................................................. 18 2.4.6 Cooperative Diversity .......................................................................................... 19 2.5 Signal Encoding Techniques ...................................................................................... 19 2.5.1 BPSK .................................................................................................................... 19 2.5.2 QPSK ................................................................................................................... 21 CHAPTER 3 .......................................................................................................................... 24 Cooperative Communications ................................................................................................. 24 3.1 Introduction ................................................................................................................ 24 3.2 Brief History of Cooperative Communication ........................................................... 25 3.3 Phases of Cooperative Transmissions ........................................................................ 26 3.3.1 Phase I: A Coordination Phase ............................................................................ 26 3.3.2 Phase II: A Cooperation Phase ............................................................................ 26 3.4 Application of Cooperative Communications ........................................................... 29 3.4.1 Cognitive Radio ................................................................................................... 29 3.4.2 Wireless Ad-hoc Network .................................................................................... 30 3.4.3 Wireless Sensor Networks (WSN) ....................................................................... 30 3.5 Communication Model .............................................................................................. 32 3.6 Channel Model ........................................................................................................... 33 3.7 Receiver Model .......................................................................................................... 33 3.8 Cooperative Communication Protocols ..................................................................... 34 3.8.1 Amplify and Forward (AAF) ............................................................................... 34 3.8.2 Decode and Forward (DAF) ................................................................................ 36 3.8.3 Detect-and-Forward (DtF) ..................................................................................
Load more

Recommended publications
  • Systems and Techniques for Multicell-MIMO and Cooperative Relaying in Wireless Networks Agisilaos Papadogiannis
    Systems and Techniques for Multicell-MIMO and Cooperative Relaying in Wireless Networks Agisilaos Papadogiannis To cite this version: Agisilaos Papadogiannis. Systems and Techniques for Multicell-MIMO and Cooperative Relaying in Wireless Networks. Electronics. Télécom ParisTech, 2009. English. pastel-00598244 HAL Id: pastel-00598244 https://pastel.archives-ouvertes.fr/pastel-00598244 Submitted on 5 Jun 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THESIS In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy from TELECOM ParisTech Specialization: Electronics and Communications Agisilaos Papadogiannis Systems and Techniques for Multicell-MIMO and Cooperative Relaying in Wireless Networks Thesis defended on the 11th of December 2009 before a committee composed of: President Prof. Jean-Claude Belfiore, TELECOM ParisTech, France Reviewers Prof. M´erouaneDebbah, SUPELEC, France Prof. Gema Pi~nero,Universidad Politechnica de Valencia, Spain Examiners Dr. Rodrigo de Lamare, University of York, UK Dr. Eric Hardouin, Orange Labs, France Thesis supervisor Prof. David Gesbert, EURECOM, France THESE pr´esent´eepour obtenir le grade de Docteur de TELECOM ParisTech Sp´ecialit´e:Electronique et Communications Agisilaos Papadogiannis Syst`emeset Techniques MIMO Coop´eratifdans les R´eseauxMulti-cellulaires Sans Fil Th`esesoutenue le 11 d´ecembre 2009 devant le jury compos´ede: Pr´esident Prof.
    [Show full text]
  • Introduction for Cooperative Diversity and Virtual MIMO
    IntroductionIntroduction forfor CooperativeCooperative DiversityDiversity andand VirtualVirtual MIMOMIMO Hsin-Yi Shen Apr 27, 2007 4/27/2007 Rensselaer Polytechnic Institute 1 OutlineOutline Introduction Cooperative Diversity and Virtual MIMO Cooperative MIMO Cooperative FEC Conclusions 4/27/2007 Rensselaer Polytechnic Institute 2 Introduction MIMO: degree-of-freedom gain & diversity gains However, MIMO requires multiple antennas at sources and receivers Cooperative diversity => achieve spatial diversity with even one antenna per-node (eg: MISO, SIMO, MIMO) Cooperative MIMO: special case of coop. diversity Achieve MIMO gains even with one antenna per-node. Eg: open-spectrum meshed/ad-hoc networks, sensor networks, backhaul from rural areas Cooperative FEC: link layer cooperation scheme for multi-hop wireless networks and sensor networks 4/27/2007 Rensselaer Polytechnic Institute 3 CooperativeCooperative DiversityDiversity Motivation In MIMO, size of the antenna array must be several times the wavelength of the RF carrier unattractive choice to achieve receive diversity in small handsets/cellular phones Cooperative diversity: Transmitting nodes use idle nodes as relays to reduce multi-path fading effect in wireless channels Methods Amplify and forward Decode and forward Coded Cooperation 4/27/2007 Rensselaer Polytechnic Institute 4 CooperativeCooperative DiversityDiversity SchemesSchemes Amplify and forward Decode and forward Coded cooperation amplify decode 0101… N1 bits N2 bits forward Frame 2 Frame 1 Relay node Relay
    [Show full text]
  • Performance Analysis of Cooperative Mimo Systems Using Decode and Forward Relaying
    19th European Signal Processing Conference (EUSIPCO 2011) Barcelona, Spain, August 29 - September 2, 2011 PERFORMANCE ANALYSIS OF COOPERATIVE MIMO SYSTEMS USING DECODE AND FORWARD RELAYING Emna Ben Yahia and Hatem Boujemaa Higher School of Communications of Tunis/TECHTRA Research Unit, University of Carthage, Tunisia [email protected], [email protected] ABSTRACT of cooperative MIMO systems. Then we derive the expres- In this paper, considering a source, a relay and a destina- sion of the diversity order. tion with multiple antennas, we provide the exact Bit Er- The paper is organized as follows. Sections 2, 3 and 4 ror Probability (BEP) of dual-hop cooperative Multiple Input presents the performance analysis of cooperative MIMO sys- Multiple Output (MIMO) systems using Decode and For- tems using DF relaying respectively in the absence and pres- ward (DF) relaying for Binary Phase Shift Keying (BPSK) ence of a direct link. For the case where we don’t have a modulation assuming independent and identically distributed direct link, we study two scenarios. The first concerns sys- (i.i.d.) Rayleigh fading channels. When the source or the re- tems where the relay has a single transmit antenna and the lay has multiple antennas, it employs an Orthogonal Space second is about systems where the relay has multiple trans- Time Block Code (OSTBC) to transmit. The receiver uses mit antennas. Section 5 gives some numerical and simulation a Maximum Likelihood (ML) decoder. We derive the ex- results. Section 6 draws some conclusions. pressions of the Moment Generating Functions (MGF), the Probability Density Functions (PDF) of the Signal-to-Noise Ratio (SNR), the exact and asymptotic BEP at the destination 2.
    [Show full text]
  • Cooperative Diversity in Wireless Networks: Relay Selection and Medium Access
    Helmut Leopold Adam Matr.-Nr. 9830200 Cooperative Diversity in Wireless Networks: Relay Selection and Medium Access DISSERTATION zur Erlangung des akademischen Grades Doktor der technischen Wissenschaften Alpen-Adria-Universit¨at Klagenfurt Fakult¨at fur¨ Technische Wissenschaften Begutachter: Univ.-Prof. Dr.-Ing. Christian Bettstetter Institut fur¨ Vernetzte und Eingebettete Systeme Alpen-Adria-Universit¨at Klagenfurt Univ.-Prof. Dr. Holger Karl Institut fur¨ Informatik Universit¨at Paderborn 08/2011 Declaration of honor I hereby confirm on my honor that I personally prepared the present academic work and carried out myself the activities directly involved with it. I also con- firm that I have used no resources other than those declared. All formulations and concepts adopted literally or in their essential content from printed, un- printed or Internet sources have been cited according to the rules for academic work and identified by means of footnotes or other precise indications of source. The support provided during the work, including significant assistance from my supervisor has been indicated in full. The academic work has not been submitted to any other examination authority. The work is submitted in printed and electronic form. I confirm that the content of the digital version is completely identical to that of the printed version. I am aware that a false declaration will have legal consequences. (Signature) (Place, date) Cooperative Diversity in Wireless Networks: Relay Selection and Medium Access Wireless communication systems suffer from a phenomenon called small scale fading which causes rapid and unpredictable fluctuations in the received signal strengths. Traditional methods to mitigate small scale fading effects impose re- strictions on the data exchange process and/or the used hardware which limit their applicability.
    [Show full text]
  • Cooperative Diversity for the Cellular Uplink: Sharing Strategies, Performance Analysis, and Receiver Design
    Graduate Theses, Dissertations, and Problem Reports 2005 Cooperative diversity for the cellular uplink: Sharing strategies, performance analysis, and receiver design Kanchan G. Vardhe West Virginia University Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Vardhe, Kanchan G., "Cooperative diversity for the cellular uplink: Sharing strategies, performance analysis, and receiver design" (2005). Graduate Theses, Dissertations, and Problem Reports. 3221. https://researchrepository.wvu.edu/etd/3221 This Thesis is protected by copyright and/or related rights. It has been brought to you by the The Research Repository @ WVU with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you must obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in WVU Graduate Theses, Dissertations, and Problem Reports collection by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. Cooperative Diversity for the Cellular Uplink: Sharing Strategies, Performance Analysis, and Receiver Design by Kanchan G. Vardhe Thesis submitted to the College of Engineering and Mineral Resources at West Virginia University in partial ful¯llment of the requirements for the degree of Master of Science in Electrical Engineering Daryl Reynolds, Ph.D., Chair Matthew C.Valenti, Ph.D. Arun Ross, Ph.D. Lane Department of Computer Science and Electrical Engineering Morgantown, West Virginia 2005 Keywords: Cooperative Diversity, MIMO, Decode and Forward, Space Time Codes, Information Outage Probability Copyright 2005 Kanchan G.
    [Show full text]
  • CD-MAC: Cooperative Diversity MAC for Robust Communication in Wireless Ad Hoc Networks
    1 CD-MAC: Cooperative Diversity MAC for Robust Communication in Wireless Ad Hoc Networks Sangman Moh, Chansu Yu, Seung-Min Park, and Heung-Nam Kim Function (DCF) in IEEE 802.11 standard [6], a node can be Abstract— In interference-rich and noisy environment, wireless regarded as a greedy adversary to other nodes in its proximity communication is often hampered by unreliable communication as they compete with each other to grab the shared medium, links. Recently, there has been active research on cooperative interfere each other’s communication, and cause collisions. At communication that improves the communication reliability by the physical layer, a node’s data transfer not only provides having a collection of radio terminals transmit signals in a cooperative way. This paper proposes a medium access control interference to other nodes depriving their opportunity of using (MAC) algorithm, called Cooperative Diversity Medium Access the medium but also incurs energy wastage by rendering them Control (CD-MAC), which exploits the cooperative to overhear. communication capability to provide robust communication in Recently, there has been active research in developing wireless ad hoc networks. In CD-MAC, each terminal proactively cooperative MAC algorithms, where nodes cooperate to selects a relay and lets it transmit simultaneously whenever accomplish the path-centric medium access rather than necessary, mitigating interference from nearby terminals and thus improving the network performance. The proposed hop-centric [2], to salvage a collided packet for each other’s CD-MAC algorithm is designed based on the widely adopted behalf at the MAC layer [35], and so on. On the other hand, IEEE 802.11 MAC for practicality.
    [Show full text]
  • A Survey on Cooperative Communication in Wireless Networks
    I.J. Intelligent Systems and Applications, 2014, 07, 66-78 Published Online June 2014 in MECS (http://www.mecs-press.org/) DOI: 10.5815/ijisa.2014.07.09 A Survey on Cooperative Communication in Wireless Networks A. F. M. Shahen Shah Institute of Information and Communication Technology, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh Email: [email protected], [email protected] Md. Shariful Islam Institute of Information Technology, University of Dhaka, Dhaka-1000, Bangladesh Email: [email protected] Abstract— Cooperative communication in wireless networks milestones in this area have been achieved, leading to a has become more and more attractive recently since it could flurry of further research activity. It is our hope that this mitigate the particularly severe channel impairments arising article will serve to illuminate the subject for a wider from multipath propagation. Here the greater benefits gained by audience, and thus accelerate the pace of developments in exploiting spatial diversity in the channel. In this paper, an this exciting technology. overview on cooperative communication in wireless networks is presented. We inscribe the benefits of cooperative transmission The mobile wireless channel suffers from fading [1], than traditional non – cooperative communication. Practical meaning that the signal attenuation can vary significantly issues and challenges in cooperative communication are over the course of a given transmission. Transmitting identified. In particular, we present a study on the advantages, independent copies of the signal generates diversity and applications and different routing strategies for cooperative can effectively combat the deleterious effects of fading. mesh networks, Ad hoc networks and wireless sensor networks.
    [Show full text]
  • Cooperative Communication Based on Random Beamforming Strategy in Wireless Sensor Networks
    1 Cooperative Communication Based on Random Beamforming Strategy in Wireless Sensor Networks Li Li, Kamesh Namuduri, Shengli Fu Electrical Engineering Department University of North Texas Denton, TX 76201 [email protected], [email protected], [email protected] Abstract—This paper presents a two-phase cooperative com- Transmitter FC munication strategy and an optimal power allocation strategy to transmit sensor observations to a fusion center in a large- scale sensor network. Outage probability is used to evaluate the performance of the proposed system. Simulation results demonstrate that: 1) when signal-to-noise ratio is low, the performance of the proposed system is better than that of the . multiple-input and multiple-output system over uncorrelated slow . fading Rayleigh channels; 2) given the transmission rate and the total transmission SNR, there exists an optimal power allocation . that minimizes the outage probability; 3) on correlated slow fading Rayleigh channels, channel correlation will degrade the system performance in linear proportion to the correlation level. Fig. 1: Cluster based sensor network model Index Terms—Multiple Input Multiple Output (MIMO), Ran- dom Beamforming In wireless sensor networks, the design of optimal sensor I. INTRODUCTION deployment strategies is influenced by energy savings. Dis- IRELESS sensor networks (WSN) received a lot of tributed cooperative communication strategies achieve energy W attention in recent years due to their applications in saving through spatial diversity [4] [5]. The use of cooperative numerous areas such as environmental monitoring, health care, transmission and/or reception of data among sensors mini- military surveillance, crisis management, and transportation. mizes the per-node energy consumption and thus increases They typically consist of a large number of sensing devices wireless sensor network’s lifetime [6].
    [Show full text]
  • Performance Analysis of MIMO Wireless Communications Over Fading Channels - a Review
    ISSN (Print) : 2320 – 3765 ISSN (Online) : 2278 – 8875 International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering Vol. 2, Issue 4, April 2013 Performance Analysis of MIMO Wireless Communications over Fading Channels - A Review Juhi Garg1, Kapil Gupta2, P. K. Ghosh3 Student, Dept. of FET, Mody Institute of Technology and Science, Lakshmangarh (Sikar), Rajasthan, India1 Assistant Professor, Dept. of FET, Mody Institute of Technology and Science, Lakshmangarh (Sikar), Rajasthan, India2 Professor, Dept. of FET, Mody Institute of Technology and Science, Lakshmangarh (Sikar), Rajasthan, India 3 Abstract: Multiple Input Multiple Output (MIMO) technology uses multiple antennas at the both link ends and does not need to increase additional transmit power and spectrum, leading to promising link capacity gains of several-fold increase in spectrum efficiency. Increased capacity can be achieved by introducing additional spatial channels that are exploited by using coding such as space-time coding (STC). The spatial diversity improves the link reliability by reducing the adverse effects of link fading and shadowing. In this article, we survey environmental factors that affect MIMO capacity. These include channel complexity, external interferences, and channel estimation errors. With the use of MIMO communication techniques, multipath need not be a hindrance and can be exploited to increase potential data rates and simultaneously improve robustness of the wireless links. This review article provides a detailed explanation of this MIMO technology and explains how such benefits can be achieved using this technological breakthrough. Keywords: Diversity, Fading channels, Combining Techniques, Wireless Communications, MIMO, STC, spatial multiplexing, Capacity, Amplify and Forward, Decode and Forward, Cooperation I.
    [Show full text]
  • Intelligent Antenna Sharing in Cooperative Diversity Wireless Networks Aggelos Anastasiou Bletsas
    Intelligent Antenna Sharing in Cooperative Diversity Wireless Networks by Aggelos Anastasiou Bletsas Diploma, Electrical and Computer Engineering, Aristotle University of Thessaloniki (1998) S.M., Media Arts and Sciences, Massachusetts Institute of Technology (2001) Submitted to the Program of Media Arts and Sciences,, School of Architecture and Planning, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Media Arts and Sciences at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY September 2005 c Massachusetts Institute of Technology 2005. All rights reserved. Author Program of Media Arts and Sciences, August 1, 2005 Certified by Andrew B. Lippman Principal Research Scientist, Program in Media Arts and Sciences MIT Media Laboratory Thesis Supervisor Accepted by Andrew B. Lippman Chairman, Departmental Committee on Graduate Studies Program in Media Arts and Sciences 2 Intelligent Antenna Sharing in Cooperative Diversity Wireless Networks by Aggelos Anastasiou Bletsas Submitted to the Program of Media Arts and Sciences,, School of Architecture and Planning, on August 1, 2005, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Media Arts and Sciences Abstract Cooperative diversity has been recently proposed as a way to form virtual antenna arrays that provide dramatic gains in slow fading wireless environments. However most of the pro- posed solutions require simultaneous relay transmissions at the same frequency bands, using distributed space-time coding algorithms. Careful design of distributed space-time coding for the relay channel, is usually based on global knowledge of some network parameters or is usually left for future investigation, if there is more than one cooperative relays. We propose a novel scheme that eliminates the need for space-time coding and provides diversity gains on the order of the number of relays in the network.
    [Show full text]
  • Macro and Micro Diversity Behaviors of Practical Dynamic Decode and Forward Relaying Schemes
    1 Macro and Micro Diversity Behaviors of Practical Dynamic Decode and Forward Relaying schemes. Melanie´ Plainchault∗, Nicolas Gresset∗, Ghaya Rekaya-Ben Othman† ∗Mitsubishi Electric R&D Centre Europe, France †Tel´ ecom´ ParisTech, France Abstract In this paper, we propose a practical implementation of the Dynamic Decode and Forward (DDF) protocol based on rateless codes and HARQ. We define the macro diversity order of a transmission from several intermittent sources to a single destination. Considering finite symbol alphabet used by the different sources, upper bounds on the achievable macro diversity order are derived. We analyse the diversity behavior of several relaying schemes for the DDF protocol, and we propose the Patching technique to increase both the macro and the micro diversity orders. The coverage gain for the open-loop transmission case and the spectral efficiency gain for the closed loop transmission case are illustrated by simulation results. Index Terms Relay channel, Dynamic Decode and Forward, Macro diversity order, Micro diversity order, Finite symbol alphabet arXiv:1106.5364v1 [cs.IT] 27 Jun 2011 I. INTRODUCTION Relays have been introduced in wireless communication systems in order to improve the transmission’s quality. Indeed, the combination of a source and a relay forms a virtual Multiple Inputs Multiple Outputs (MIMO) scheme providing diversity and robustness to fadings. Two main relaying protocols can be distinguished in the literature: the Amplify and Forward (AF) protocol and the Decode and Forward (DF) protocol. For the AF protocol, the relay transmits an amplified copy of the previously received signal. The main drawback of this protocol is the noise amplification.
    [Show full text]
  • Cooperative Diversity in Wireless Networks: Efficient Protocols and Outage Behavior
    IEEE TRANS. INFORM. THEORY 1 Cooperative Diversity in Wireless Networks: Efficient Protocols and Outage Behavior J. Nicholas Laneman, Member, IEEE, David N. C. Tse, Senior Member, IEEE, and Gregory W. Wornell, Senior Member, IEEE Abstract We develop and analyze cooperative diversity protocols that combat fading induced by multipath propagation in wireless networks. The underlying techniques exploit space diversity available through cooperating terminals’ relaying signals for one another. We outline several low-complexity strategies employed by the cooperating radios, including fixed relaying schemes such as amplify-and-forward and decode-and-forward, selection relaying schemes that adapt based upon channel measurements between the cooperating terminals, and incremental relaying schemes that adapt based upon limited feedback from the destination terminal. We develop performance characterizations in terms of outage events and associated outage probabilities, which measure robustness of the transmissions to fading, focusing on the high signal-to-noise (SNR) ratio regime. Except for fixed decode-and-forward, all of our cooperative diversity protocols achieve full diversity (i.e., second-order diversity in the case of two terminals), and are close to optimum (within 1:5 decibels (dB)) in certain regimes. Thus, using distributed antennas, we can provide the powerful benefits of space diversity without need for physical arrays, though at a loss of spectral efficiency due to half-duplex operation and possibly additional receive hardware. Applicable to Manuscript submitted January 22, 2002; revised Aug. 6, 2003. The material in this paper was presented in part at the Allerton Conference on Control, Communications, and Signal Processing, Urbana, IL, October 2000, and the International Symposium on Information Theory, Washington, DC, June 2001.
    [Show full text]