Diversity Reception in Radiocommunication Links
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Performance Comparisons of MIMO Techniques with Application to WCDMA Systems
EURASIP Journal on Applied Signal Processing 2004:5, 649–661 c 2004 Hindawi Publishing Corporation Performance Comparisons of MIMO Techniques with Application to WCDMA Systems Chuxiang Li Department of Electrical Engineering, Columbia University, New York, NY 10027, USA Email: [email protected] Xiaodong Wang Department of Electrical Engineering, Columbia University, New York, NY 10027, USA Email: [email protected] Received 11 December 2002; Revised 1 August 2003 Multiple-input multiple-output (MIMO) communication techniques have received great attention and gained significant devel- opment in recent years. In this paper, we analyze and compare the performances of different MIMO techniques. In particular, we compare the performance of three MIMO methods, namely, BLAST, STBC, and linear precoding/decoding. We provide both an analytical performance analysis in terms of the average receiver SNR and simulation results in terms of the BER. Moreover, the applications of MIMO techniques in WCDMA systems are also considered in this study. Specifically, a subspace tracking algo- rithm and a quantized feedback scheme are introduced into the system to simplify implementation of the beamforming scheme. It is seen that the BLAST scheme can achieve the best performance in the high data rate transmission scenario; the beamforming scheme has better performance than the STBC strategies in the diversity transmission scenario; and the beamforming scheme can be effectively realized in WCDMA systems employing the subspace tracking and the quantized feedback approach. Keywords and phrases: BLAST, space-time block coding, linear precoding/decoding, subspace tracking, WCDMA. 1. INTRODUCTION ing power and/or rate over multiple transmit antennas, with partially or perfectly known channel state information [7]. -
OFDM System for High Data Rate and High Mobility Umesha G B Dr
Special Issue - 2018 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 NCESC - 2018 Conference Proceedings OFDM System for High Data Rate and High Mobility Umesha G B Dr. M N Shanmukha Swamy Research Scholar Professor & HOD Department of ECE, SJCE Department of ECE, SJCE Mysore, Karnataka Mysore, Karnataka. Abstract---In recent years, there has been considerable second reason to study the downlink. Generally, the growth in interest in wireless access to wide area data portable or handheld devices envisioned (e.g., PDAs, networks at high data rates. This growth has been fuelled by notebook PCs or handsets), will be battery powered. the simultaneous development of the high-speed wired data Increasing uplink data rates by orders of magnitude networks (e.g., the Internet), wide-spread availability of requires increases in portable transmit power to meet the powerful mobile computing devices, rapidly dropping prices for increasingly sophisticated electronic devices, plus the link budget, a major challenge with foreseeable battery global deployment of wireless voice systems. High-mobility technology [13, 14]. However, readily applicable downlink wireless data access at near-LAN rates is likely to be an techniques can attain the high peak data rates desired. attractive option. The harsh cellular radio environment creates significant challenges when trying to provide access at 2. OFDM BACKGROUND high data rates, especially if high-mobility and wide-area availability are expected even more so when considering the Four major impairments to the operation of wireless constraints placed on the system design by terminal size and communications networks are, delay spread, noise, power constraints. -
MIMO Systems and Transmit Diversity 1 Introduction 2 MIMO Capacity Analysis
MIMO Systems and Transmit Diversity 1 Introduction So far we have investigated the use of antenna arrays in interference cancellation and for receive diversity. This final chapter takes a broad view of the use of antenna arrays in wireless communi- cations. In particular, we will investigate the capacity of systems using multiple transmit and/or multiple receive antennas. This provides a fundamental limit on the data throughput in multiple- input multiple-output (MIMO) systems. We will also develop the use of transmit diversity, i.e., the use of multiple transmit antennas to achieve reliability (just as earlier we used multiple receive antennas to achieve reliability via receive diversity). The basis for receive diversity is that each element in the receive array receives an independent copy of the same signal. The probability that all signals are in deep fade simultaneously is then significantly reduced. In modelling a wireless communication system one can imagine that this capability would be very useful on transmit as well. This is especially true because, at least in the near term, the growth in wireless communications will be asymmetric internet traffic. A lot more data would be flowing from the base station to the mobile device that is, say, asking for a webpage, but is receiving all the multimedia in that webpage. Due to space considerations, it is more likely that the base station antenna comprises multiple elements while the mobile device has only one or two. In addition to providing diversity, intuitively having multiple transmit/receive antennas should allow us to transmit data faster, i.e., increase data throughput. -
Multiple Antenna Technologies
Multiple Antenna Technologies Manar Mohaisen | YuPeng Wang | KyungHi Chang The Graduate School of Information Technology and Telecommunications INHA University ABSTRACT the receiver. Alamouti code is considered as the simplest transmit diversity scheme while the receive diversity includes maximum ratio, equal gain and selection combining Multiple antenna technologies have methods. Recently, cooperative received high attention in the last few communication was deeply investigated as a decades for their capabilities to improve the mean of increasing the communication overall system performance. Multiple-input reliability by not only considering the multiple-output systems include a variety of mobile station as user but also as a base techniques capable of not only increase the station (or relay station). The idea behind reliability of the communication but also multiple antenna diversity is to supply the impressively boost the channel capacity. In receiver by multiple versions of the same addition, smart antenna systems can increase signal transmitted via independent channels. the link quality and lead to appreciable On the other hand, multiple antenna interference reduction. systems can tremendously increase the channel capacity by sending independent signals from different transmit antennas. I. Introduction BLAST spatial multiplexing schemes are a good example of such category of multiple Multiple antennas technologies proposed antenna technologies that boost the channel for communications systems have gained capacity. much attention in the last few years because In addition, smart antenna technique can of the huge gain they can introduce in the significantly increase the data rate and communication reliability and the channel improve the quality of wireless transmission, capacity levels. Furthermore, multiple which is limited by interference, local antenna systems can have a big contribution scattering and multipath propagation. -
Performance Analysis of Diversity Techniques for Wireless Communication System
1 Performance Analysis of Diversity Techniques for Wireless Communication System Md. Jaherul Islam [email protected] This Thesis is a part (30 ECTS) of Master of Science degree (120 ECTS) in Electrical Engineering emphasis on Telecommunication Blekinge Institute of Technology February 12 Blekinge Institute of Technology School of Engineering Department of Telecommunication Supervisor: Magnus G Nilsson Examiner: Magnus G Nilsson Contact: [email protected] 2 Abstract Different diversity techniques such as Maximal-Ratio Combining (MRC), Equal-Gain Combining (EGC) and Selection Combining (SC) are described and analyzed. Two branches (N=2) diversity systems that are used for pre-detection combining have been investigated and computed. The statistics of carrier to noise ratio (CNR) and carrier to interference ratio (CIR) without diversity assuming Rayleigh fading model have been examined and then measured for diversity systems. The probability of error ( ) vs CNR and ( ) versus CIR have also been obtained. The fading dynamic range of the instantaneous CNR and CIR is reduced remarkably when diversity systems are used [1]. For a certain average probability of error, a higher valued average CNR and CIR is in need for non-diversity systems [1]. But a smaller valued of CNR and CIR are compared to diversity systems. The overall conclusion is that maximal-ratio combining (MRC) achieves the best performance improvement compared to other combining methods. Diversity techniques are very useful to improve the performance of high speed wireless channel to transmit data and information. The problems which considered in this thesis are not new but I have tried to organize, prove and analyze in new ways. -
A Comparison Between Synchronous CDMA and Orthogonal Frequency Division Multiplexing (OFDM) for Fixed Broadband Wireless Access
A Comparison Between Synchronous CDMA and Orthogonal Frequency Division Multiplexing (OFDM) for Fixed Broadband Wireless Access Shital Ratilal Chheda Thesis submitted to the Faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering Charles W. Bostian, Chair Ira Jacobs Dennis G. Sweeney April 15, 2002 Blacksburg, Virginia Keywords: CDMA, OFDM, synchronous, broadband, wireless, 3G, Non-Line-of- Sight (NLOS), orthogonal, VOFDM, SCDMA Copyright 2002, Shital Ratilal Chheda A Comparison Between Synchronous CDMA and Orthogonal Frequency Division Multiplexing (OFDM) for Fixed Broadband Wireless Access Shital Ratilal Chheda (ABSTRACT) The growth of broadband Internet access has paved the way for the development of many new technologies. As the cost of implementing broadband access soars, the best alternative will be to use fixed wireless for these services. This thesis addresses the possibility of 3rd Generation (3G) mobile cellular wireless systems as the basis for fixed broadband wireless service. Two of the 3G technologies aimed at providing fixed broadband wireless access are Time Division Synchronous Code Division Multiple Access (TD-SCDMA) and Orthogonal Frequency Division Multiplexing (OFDM). This thesis aims to provide a preliminary study on using TD-SCDMA and OFDM for broadband wireless systems. Currently, there is not enough theory and information to establish the feasibility of using either of these technologies for broadband wireless access. First, the basic features and background on synchronous CDMA and OFDM are presented for the reader to better understand these technologies. Then, an example TD-SCDMA system is described, and some analytical and experimental results are presented. -
Effective Radio Resource Management for Multimedia Broadcast/Multicast Services in UMTS Networks
Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2006, Article ID 70903, Pages 1–12 DOI 10.1155/WCN/2006/70903 Effective Radio Resource Management for Multimedia Broadcast/Multicast Services in UMTS Networks Nuno Souto,1, 2 Armando Soares,2 Patricia Eusebio,´ 2 Americo´ Correia,1, 2 and Joao˜ C. Silva1 1 Instituto de Telecomunicac¸oes,˜ Avenue Rovisco Pais 1, 1049-001 Lisboa, Portugal 2 Associac¸ao˜ para o Desenvolvimento das Telecomunicac¸oes˜ e T´ecnicas de Informatica,´ Avenue das Forc¸as Armadas, Edif´ıcio ISCTE, 1600-082 Lisboa, Portugal Received 29 September 2005; Revised 3 February 2006; Accepted 26 May 2006 Broadcast and multicast offer a significant improvement of spectrum utilization, and become particularly important where in- formation channels are shared among several users. Mobile cellular environments are expected to evolve with the technological approaches necessary to facilitate the deployment of multimedia services, such as streaming, file download, and carousel services. The perspective that video streaming in wireless networks services is an attractive service to end-users has spurred the research in this area. To provide for a video delivery platform in UMTS, the third generation partnership project (3GPP) addressed this problem with the introduction of the multimedia broadcast and multicast services (MBMS) in 3GPP Release 6. In this document we analyse several effective radio resource management techniques to provide MBMS, namely, use of nonuniform QAM constel- lations, multicode, and macrodiversity to guarantee the optimal distribution of QoS depending on the location of mobiles. Copyright © 2006 Nuno Souto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. -
Great Expectations: the Value of Spatial Diversity in Wireless Networks
Great Expectations: The Value of Spatial Diversity in Wireless Networks SUHAS N. DIGGAVI, MEMBER, IEEE, NAOFAL AL-DHAHIR, SENIOR MEMBER, IEEE, A. STAMOULIS, MEMBER, IEEE, AND A. R. CALDERBANK, FELLOW, IEEE Invited Paper In this paper, the effect of spatial diversity on the throughput The challenge here is that Moore’s Law does not seem to and reliability of wireless networks is examined. Spatial diversity apply to rechargeable battery capacity, and though the den- is realized through multiple independently fading transmit/re- sity of transistors on a chip has consistently doubled every ceive antenna paths in single-user communication and through independently fading links in multiuser communication. Adopting 18 mo, the energy density of batteries only seems to double spatial diversity as a central theme, we start by studying its every 10 years. This need to conserve energy (see [2] and ref- information-theoretic foundations, then we illustrate its benefits erences therein) leads us to focus on what is possible when across the physical (signal transmission/coding and receiver signal signal processing at the terminal is limited. Throughout this processing) and networking (resource allocation, routing, and paper, we use the cost and complexity of the receiver to applications) layers. Throughout the paper, we discuss engineering intuition and tradeoffs, emphasizing the strong interactions be- bound the resources available for signal processing. Wireless tween the various network functionalities. spectrum itself is a valuable resource that also needs to be conserved given the economic imperative of return on multi- Keywords—Ad hoc networks, channel estimation, diversity, fading channels, hybrid networks, information theory for wireless billion-dollar investments by wireless carriers [1]. -
Diversity Diversity Macrodiversity Microdiversity
Ch13. Diversity Instructor: • Mohammed Taha O. El Astal LOGO 13.1 Introduction AWGN channels Rayleigh Fading In AWGN, it may that a 10-dB SNR leads to BERs on the order of 10−4. but in fading channels, we need an SNR on the order of 40 dB in order to achieve a 10−4 BER, which is clearly unpractical. CONT. deep fading (very low SNR) The reason ??? is the fading of the channel; since the fading cause to have an attenuation being large, and thus of the instantaneous SNR being low, so the BER be high. CONT. The Solution!!!! Make sure that the SNR at Rx. has a smaller probability of being low. =make sure that the signal has a smaller probability to have a large attenuation 13.1.1 Principle of Diversity The principle of diversity is to ensure that the same information reaches the receiver (RX) on statistically independent channels. Example: SNR BER-DFSK If Pnoise is 50 pW. Consider the following two cases : 0dB 0.5 An AWGN channel with Psig,avg is 1 nW. A fading channel where during 90% of the time the ....... …... received power is 1.11 nW, while for the remainder, it is …… …… zero. 13dB 10−9 1. Compute BER for the case of AWGN channel. 13.5dB 10−10 2. Compute avg. BER with assuming it is selection diversity in the following cases: a. one received antenna. b. two received antenna. c. three received antenna 13.1.2 Definition of the Correlation Coefficient Any correlation between the fading of the channels decreases the effectiveness of diversity, why?? The most important one is the correlation coefficient of signal envelopes x and y: For two statistically independent signals E{xy} = E{x}E{y} ρxy=0 Signals are often said to be “effectively” decorrelated if ρ is below a certain threshold (typically 0.5 or 0.7). -
DIVERSITY TECHNIQUES Prepared by Deepa.T, Asst.Prof. /TCE
DIVERSITY TECHNIQUES Prepared by Deepa.T, Asst.Prof. /TCE Introduction •Three techniques are used independently or in tandem to improve receiver signal quality •Equalization compensates for ISI created by multipath with time dispersive channels (W>BC) ¾Linear equalization, nonlinear equalization •Diversity also compensates for fading channel impairments, and is usually implemented by using two or more receiving antennas ¾Spatial diversity, antenna polarization diversity, frequency diversity, time diversity Diversity Diversity: It is the technique used to compensate for fading channel impairments. It is implemented by using two or more receiving antennas. While Equalization is used to counter the effects of ISI, Diversity is usually employed to reduce the depth and duration of the fades experienced by a receiver in a flat fading channel. These techniques can be employed at both base station and mobile receivers. Spatial Diversity is the most widely used diversity technique. Spatial Diversity Technique‐ A Brief Description In this technique multiple antennas are strategically spaced and connected to common receiving system. While one antenna sees a signal null, one of the other antennas may see a signal peak, and the receiver is able to select the antenna with the best signal at any time. The CDMA systems use Rake receivers which provide improvement through time diversity. Diversity Techniques‐ Highlights • Unlike Equalization, Diversity requires no training overhead as a transmitter doesn’t require one. •It provides significant link improvement with little added cost. •It exploits random nature of wave propagation by finding independent ( uncorrelated) signal paths for communication. Fundamentals of Equalization ISI has been recognized as the major obstacle to high speed data transmission over mobile radio channels. -
Embms) Muhammad Moiz Anis, Xavier Lagrange, Ramesh Pyndiah
Overview of evolved Multimedia Broadcast Multicast Services (eMBMS) Muhammad Moiz Anis, Xavier Lagrange, Ramesh Pyndiah To cite this version: Muhammad Moiz Anis, Xavier Lagrange, Ramesh Pyndiah. Overview of evolved Multimedia Broad- cast Multicast Services (eMBMS). [Research Report] RR-2016-01-RSM, Dépt. Réseaux, Sécurité et Multimédia (Institut Mines-Télécom-Télécom Bretagne-UEB); Institut de recherche en informatique et systèmes aléatoires (UMR CNRS 6074 - Université de Rennes 1 - INRIA - INSA de Rennes - ENS de Cachan - Télécom Bretagne - Université de Bretagne Sud); Usman Institute of Technology - Hamdard University (.); Laboratoire en sciences et technologies de l’information, de la communication et de la connaissance (UMR CNRS 6285 - Télécom Bretagne - Université de Bretagne Occidentale - Université de Bretagne Sud); Dépt. Signal et Communications (Institut Mines-Télécom-Télécom Bretagne-UEB); Direction scientifique (Institut Mines-Télécom -Télécom Bretagne). 2016, pp.48. hal-01291201 HAL Id: hal-01291201 https://hal.archives-ouvertes.fr/hal-01291201 Submitted on 21 Mar 2016 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 -
The Multiply-Detected Macrodiversity Scheme for Wireless Cellular Systems
506 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, VOL. 47, NO. 2, MAY 1998 The Multiply-Detected Macrodiversity Scheme for Wireless Cellular Systems Zygmunt J. Haas, Senior Member, IEEE, and Chih-Peng Li, Member, IEEE Abstract—In this paper, the multiply-detected macrodiversity 1) the signal1 with the strongest received power—the (S) (MDM) scheme is proposed for wireless cellular systems. As diversity; opposed to the traditional macrodiversity schemes, in which at 2) the signal with the largest signal-to-interference ratio any time a signal from only one base station is selected, in the MDM scheme there is no selection, but all the received signals (SIR)—the signal-to-interference (S/I) diversity; are detected, and a maximum-likelihood decision algorithm is 3) the signal with the largest signal plus interference employed to maximize the probability of correct decision. We power—the (S I) diversity. study the performance of the MDM scheme and compare it with Of course, as the SIR directly determines the bit-error rate the performance of the traditional selection-based macrodiversity schemes. Depending on the propagation parameters, our results (BER), the (S/I) diversity corresponds to the best performing show that through the use of the MDM scheme, significant system. Thus, we adopt the (S/I) diversity as the comparison improvement in the bit-error rate (BER) can be achieved. For basis for the MDM scheme. However, practically, the (S/I) R instance, if the outage probability is defined as BER above 10 , diversity is also the most difficult scheme to implement. the outage is eliminated at least 45% of the time as compared with Various studies have analyzed network architectures em- signal-to-interference (S/I) diversity, for a propagation attenua- tion exponent of 4.0 and shadowing standard deviation of 4.0 ploying selection-based macroscopic diversity.