Author: Md. Tofazzal Hossain Publisher: ISBN: Category : Languages : en Pages : 448
Book Description
In this work the effect of perfect and imperfect synchronization on the performance of single-link and cooperative communication is investigated. A feedforward non-data-aided near maximum likelihood (NDA-NML) timing estimator which is effective for an additive white Gaussian noise (AWGN) channel and also for a flat-fading channel, is developed. The Cramer Rao bound (CRB) and modified Cramer Rao bound (MCRB) for the estimator for a single-link transmission over an AWGN channel is derived. A closed form expression for the probability distribution of the timing estimator is also derived. The bit-error-rate (BER) degradation of the NDA-NML timing estimator with raised cosine pulse shaping for static timing errors over an AWGN channel is characterized. A closed form expression is derived for the conditional bit error probability (BEP) with static timing errors of binary phase shift keying modulation over a Rayleigh fading channel using rectangular pulse shaping.
Author: Xiao Li Publisher: ISBN: 9781374701700 Category : Languages : en Pages :
Book Description
This dissertation, "Channel Estimation and Timing Synchronization in Cooperative Communication Systems" by Xiao, Li, 李驍, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b4284183 Subjects: Algorithms Signal processing - Mathematical models Wireless communication systems
Author: Yuzhe Yao Publisher: ISBN: Category : Languages : en Pages :
Book Description
Synchronization is one of the most important issues in wireless communication systems design and implementation. The requirement for synchronization is going high as the signal bandwidth and the system complexity increases. For instance, the ultra-short pulse width in ultra-wideband (UWB) communication systems poses problems to the conventional timing synchronization methods and the multi-node transmission poses problems to the existing carrier frequency offset (CFO) synchronization methods. Moreover, the impact of imperfect synchronization in these systems on the system performance is more negative than that of the conventional communication systems. Therefore, efficient synchronization algorithms are really in need. This dissertation presents several synchronization methods aiming to either improve the synchronization performance or reduce the synchronization complexity. The focus of this dissertation is on UWB systems and cooperative systems. Both timing synchronization and carrier frequency synchronization problems have been investigated. Several different systems are considered, including the point to point block transmission based UWB communications, orthogonal frequency division multiplexing (OFDM) based one way and two way relaying communication systems and narrow band cooperative communication systems. For block transmission UWB systems, i.e., both OFDM and single carrier frequency domain equalization (SC-FDE) UWB systems, a new generic timing estimation method based on channel impulse response (CIR) estimation is proposed. The newly proposed method is superior to the existing methods not only in synchronization performance, but also in the algorithm complexity. For the multi-node cooperative communications, the CFO mitigation issue is studied with OFDM signaling. Due to the distributed nature of the cooperative system, the multiple CFO problem is inevitable and hard to solve. A two-step compensation scheme is designed to suppress the interference introduced by multiple CFO with low complexity. Moreover, timing synchronization in cooperative communications is studied, including the broadband OFDM based cooperative communication and the narrow band cooperative communication. A means of determining the optimal timing of the OFDM signal in asynchronous two way relay networks (TWRN) has been designed. A correlation based multi-delay estimation method is proposed for narrow band asynchronous cooperative communication systems. The synchronization issues covering both timing and carrier synchronization have been extensively studied in this dissertation. New synchronization methods have been proposed for the emerging transmission schemes such as high rate UWB transmission and the distributed cooperative transmission with challenges different from conventional wireless transmission schemes.
Author: Stefan Berger Publisher: Logos Verlag Berlin GmbH ISBN: 383252536X Category : Languages : en Pages : 337
Book Description
In this thesis, several important aspects of cooperative wireless multiuser networks are investigated. The focus lies on coherent two-hop relaying networks where several amplify-and-forward (AF) relays assist the communication between multiple source-destination pairs. First, the impact of local oscillator (LO) imperfections and I/Q imbalance at the relays on two-hop relaying is investigated. A special focus lies on the comparison between frequency division duplexing (FDD) and time division duplexing (TDD) relays. Based on the observation that the direction in which a channel between two wireless nodes is measured has an impact on the estimate, phase synchronization requirements for coherent relaying networks are then found. Several channel estimation protocols that differ in the direction in which the single-hop channels are measured are furthermore identi'ed and their performance is compared. Next, a very simple phase synchronization scheme is presented that provides a set of relays with a common LO phase. Two coherent beamforming schemes, namely multiuser zero-forcing (MUZF) and multiuser minimum mean squared error (MMSE) relaying, are then investigated. Finally, a real-world demonstrator for distributed wireless communication networks (called RACooN Lab) is presented. It was used to implement coherent cooperative communication schemes on a practical two-hop relaying network.
Author: Yan Zhang Publisher: CRC Press ISBN: 1420064703 Category : Computers Languages : en Pages : 518
Book Description
Cooperative devices and mechanisms are increasingly important to enhance the performance of wireless communications and networks, with their ability to decrease power consumption and packet loss rate and increase system capacity, computation, and network resilience. Considering the wide range of applications, strategies, and benefits associated wit
Author: Ali Arshad Nasir Publisher: ISBN: Category : Computer algorithms Languages : en Pages : 306
Book Description
Cooperative communication is an attractive solution to combat fading in wireless communication systems. Achieving synchronization is a fundamental requirement in such systems. In cooperative networks, multiple single antenna relay terminals receive and cooperatively transmit the source information to the destination. The multiple distributed nodes, each with its own local oscillator, give rise to multiple timing offsets (MTOs) and multiple carrier frequency offsets (MCFOs). Particularly, the received signal at the destination is the superposition of the relays' transmitted signals that are attenuated differently, are no longer aligned with each other in time, and experience phase rotations at different rates due to different channels, MTOs, and MCFOs, respectively. The loss of synchronization due to the presence of MTOs and MCFOs sets up the recovery of the source signal at the destination to be a very challenging task. This thesis seeks to develop estimation and compensation algorithms that can achieve synchronization and enable cooperative communication for both decode-and-forward (DF) and amplify-and-forward (AF) relaying networks in the presence of multiple impairments, i.e., unknown channel gains, MTOs, and MCFOs. In the first part of the thesis, a training-based transmission scheme is considered, in which training symbols are transmitted first in order to assist the joint estimation of multiple impairments at the destination node in DF and AF cooperative relaying networks. New transceiver structure at the relays and novel receiver design at the destination are proposed which allow for the decoding of the received signal in the presence of unknown channel gains, MTOs, and MCFOs. Different estimation algorithms, e.g., least squares (LS), expectation conditional maximization (ECM), space-alternating generalized expectation-maximization (SAGE), and differential evolution (DE), are proposed and analyzed for joint estimation of multiple impairments. In order to compare the estimation accuracy of the proposed estimators, Cramer-Rao lower bounds (CRLBs) for the multi-parameter estimation are derived. Next, in order to detect the signal from multiple relays in the presence of multiple impairments, novel optimal and sub-optimal minimum mean-square error (MMSE) compensation and maximum likelihood (ML) decoding algorithm are proposed for the destination receiver. It has been evidenced by numerical simulations that application of the proposed estimation and compensation methods in conjunction with space-time block codes achieve full diversity gain in the presence of channel and synchronization impairments. Considering training-based transmission scheme, this thesis also addresses the design of optimal training sequences for efficient and joint estimation of MTOs and multiple channel parameters. In the second part of the thesis, the problem of joint estimation and compensation of multiple impairments in non-data-aided (NDA) DF cooperative systems is addressed. The use of blind source separation is proposed at the destination to convert the difficult problem of jointly estimating the multiple synchronization parameters in the relaying phase into more tractable sub-problems of estimating many individual timing offsets and carrier frequency offsets for the independent relays. Next, a criteria for best relay selection is proposed at the destination. Applying the relay selection algorithm, simulation results demonstrate promising bit-error rate (BER) performance and realise the achievable maximum diversity order at the destination.
Author: Stephan Sand Publisher: John Wiley & Sons ISBN: 0470770643 Category : Technology & Engineering Languages : en Pages : 277
Book Description
Positioning in Wireless Communications Systems explains the principal differences and similarities of wireless communications systems and navigation systems. It discusses scenarios which are critical for dedicated navigation systems such as the Global Positioning System (GPS) and which motivate the use of positioning based on terrestrial wireless communication systems. The book introduces approaches for determination of parameters which are dependent on the position of the mobile terminal and also discusses iterative algorithms to estimate and track the position of the mobile terminal. Models for radio propagation and user mobility are important for performance investigations and assessments using computer simulations. Thus, channel and mobility models are explored, especially focussing on critical navigation environments like urban or indoor scenarios. Positioning in Wireless Communications Systems examines advanced algorithms such as hybrid data fusion of satellite navigation and positioning with wireless communications and cooperative positioning among mobile terminals.. The performance of the discussed positioning techniques are explored on the basis of already existing and operable terrestrial wireless communication systems such as GSM, UMTS, or LTE and it is shown how positioning issues are fixed in respective standards. Written by industry experts working at the cutting edge of technological development, the authors are well placed to give an excellent view on this topic, enabling in-depth coverage of current developments. Key features • Unique in its approach to dealing with a heterogeneous system approach, different cell structures and signal proposals for future communications systems • Covers hybrid positioning investigating how GNSS and wireless communications positioning complement each other • Applications and exploitation of positioning information are discussed to show the benefits of including this information in several parts of a wireless communications system
Author: Mohamed Ibnkahla Publisher: CRC Press ISBN: 1420046020 Category : Technology & Engineering Languages : en Pages : 520
Book Description
Adaptive techniques play a key role in modern wireless communication systems. The concept of adaptation is emphasized in the Adaptation in Wireless Communications Series through a unified framework across all layers of the wireless protocol stack ranging from the physical layer to the application layer, and from cellular systems to next-generation wireless networks. This specific volume, Adaptive Signal Processing in Wireless Communications is devoted to adaptation in the physical layer. It gives an in-depth survey of adaptive signal processing techniques used in current and future generations of wireless communication systems. Featuring the work of leading international experts, it covers adaptive channel modeling, identification and equalization, adaptive modulation and coding, adaptive multiple-input-multiple-output (MIMO) systems, and cooperative diversity. It also addresses other important aspects of adaptation in wireless communications such as hardware implementation, reconfigurable processing, and cognitive radio. A second volume in the series, Adaptation and Cross-layer Design in Wireless Networks(cat no.46039) is devoted to adaptation in the data link, network, and application layers.
Author: K. J. Ray Liu Publisher: Cambridge University Press ISBN: 0521895138 Category : Computers Languages : en Pages : 643
Book Description
Presents the fundamentals of cooperative communications and networking with a holistic approach to principal topics where improvements can be obtained.
Author: Md. Tofazzal Hossain
Author: Xiao Li
Author: Yuzhe Yao
Author: Stefan Berger
Author: Yan Zhang
Author: Ali Arshad Nasir
Author: Xiao Li (electronic engineer.)
Author: Stephan Sand
Author: Mohamed Ibnkahla
Author: K. J. Ray Liu