Download or read book OFDM Interference Mitigation Algorithms with Application to DVB H written by Sili Lu and published by . This book was released on 2008 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal frequency-division multiplexing (OFDM) has gained an increased popularity over the last few years and has been adopted as the modulation scheme of choice for beyond 3G mobile communication systems. This is mainly due to its high robustness to time dispersion effects and its low implementation complexity. DVB-H is the latest development within the set of Digital Video Broadcasting (DVB) standards that use OFDM as a modulation scheme. DVB-H is required to operate under high mobility conditions resulting in significant Inter-Carrier Interference (ICI). Under these conditions, the conventional one-tap per subcarrier channel estimation and equalization scheme is suboptimal since it does not account for ICI effects due to channel time-variation within an OFDM symbol. To mitigate ICI, we propose in this dissertation a simplified hybrid frequency/time-domain channel estimation algorithm. In addition, we design a reduced-complexity Q -tap frequency-domain equalizer (FEQ) and enhance its performance by integrating it with joint channel and data estimation and an ICI-mitigating pilot/data placement scheme. We also investigate differential OFDM detection as a low-complexity alternative for coherent detection and test its performance in the presence of Doppler for DVB-H system. Furthermore, we extend our approach to multiple-input multiple-out (MIMO) OFDM systems. We design a novel embedded space-frequency block code (SFBC)-OFDM scheme that performs well under high Doppler. We also propose a novel standard-conformable Cyclic Delay Diversity (CDD) scheme and its associated channel estimation scheme for comb-type OFDM transmissions, which achieves the Cramer-Rao lower bound on channel estimation mean square error.
Download or read book A Study on Co channel Interference Cancellation Algorithms for OFDM Based Mobile Communication Systems written by Zhenyu Zhou and published by . This book was released on 2011 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Complexity Iterative Receiver Design for OFDM Systems written by Vamadevan Namboodiri and published by . This book was released on 2012 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single Input Single Output (SISO) Orthogonal Frequency Division Multiplexing (OFDM) systems have been adopted in many of the recent wireless communication standards such as European terrestrial broadcast systems based on DVB-H, DVB-T and DVB-T2. For OFDM systems, cyclic prefix of sufficient length makes the receiver design simple in frequency-selective multipath environments. Wireless communication based on Multiple Input Multiple Output (MIMO) systems has gained popularity due to the potential capacity increases it can provide. MIMO-OFDM based transmission systems can thus provide very high data rates with a relatively simple receiver design and are now adopted widely in recent wireless communication standards such as Long Term Evolution (LTE), WiMAX and WiFi. Modern wireless communication applications, both SISO and MIMO, require high data rates at high carrier frequencies and at high levels of mobility. This results in less intercarrier spacing and severe time-varying frequency-selective multipath fading, which breaks the orthogonality of subcarriers and causes intercarrier interference (ICI) in the received signal thus severely impacting the BER performance of the receiver. Hence, efficient receiver design which is fundamental to any communication system is ever more relevant. Turbo iterative receivers (IR) are based on the observation that performance of the system can be significantly improved if detection and decoding are combined together. They, in general, are found to have superior performance compared to other solutions, however turbo IRs usually suffer from high computational complexity which makes their implementation expensive. Such practical application challenges motivate us to propose a new, low complexity, Turbo IR for SISO and MIMO OFDM systems under time varying frequency selective channel conditions. Motivated by the classical TE, we first propose a sub-optimal, successive interference cancellation and MAP decoding (SIC-MAP) algorithm for SISO systems. In SIC-MAP, copies of the received signal on the same and adjacent subcarriers are carefully combined to take advantage of the frequency diversity (on account of the time variations of the channel) while eliminating the interference from the other transmit symbols leveraging the feedback information from the decoder. The resulting system matrix becomes a single column vector which allows an easy MAP decoding. BER performance, computation complexity, and convergence behavior of the proposed scheme has been contrasted with two other similar schemes. It has been found that SIC-MAP, while having near identical performance to the competing schemes, can be implemented approximately with only a third of their computational complexity. Subsequently, we extend the above detection idea, SIC-MAP, to MIMO systems (SIC-MAP-MIMO). Unlike single antenna systems, even under static multipath channel conditions, the received signal in a MIMO receiver is corrupted by the co-antenna interference (CAI), thus making the detection task more challenging. SIC-MAP-MIMO algorithm achieves comparable BER performance to the competing equalization schemes but with even more computational savings than SISO. A low complexity Least Squares (LS) based iterative channel estimation scheme using soft feedback information has also been proposed. This scheme is especially suitable when the number of significant channel taps is higher than the number of pilots, a phenomenon that is often encountered in practical systems.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2009 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interference Mitigation for Multi band OFDM Using Diversity Combining and Erasure Based Methods written by Eric Paul Reinbold and published by . This book was released on 2005 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interference Cancellation Methods in MIMO OFDM Systems written by Sreekanth Neriyanuru and published by LAP Lambert Academic Publishing. This book was released on 2015-01-19 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, Survey and investigation on inter symbol interference (ISI) and inter carrier interference (ICI) due to either carrier frequency offset or timing offset issues and interference mitigation schemes available, compare and analyze their bit error rate performance to various schemes for OFDM and MIMO-OFDM systems. Efforts have been made to develop an efficient interference cancelling receiver for ISI and ICI, algorithms to be implemented on MATLAB environment for OFDM and MIMO-OFDM which are not available in literature.
Download or read book Wireless Communications Over Rapidly Time Varying Channels written by Franz Hlawatsch and published by Academic Press. This book was released on 2011-05-04 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a result of higher frequencies and increased user mobility, researchers and systems designers are shifting their focus from time-invariant models to channels that vary within a block. Wireless Communications Over Rapidly Time-Varying Channels explains the latest theoretical advances and practical methods to give an understanding of rapidly time varying channels, together with performance trade-offs and potential performance gains, providing the expertise to develop future wireless systems technology. As well as an overview of the issues of developing wireless systems using time-varying channels, the book gives extensive coverage to methods for estimating and equalizing rapidly time-varying channels, including a discussion of training data optimization, as well as providing models and transceiver methods for time-varying ultra-wideband channels. An introduction to time-varying channel models gives in a nutshell the important issues of developing wireless systems technology using time-varying channels Extensive coverage of methods for estimating and equalizing rapidly time-varying channels, including a discussion of training data optimization, enables development of high performance wireless systems Chapters on transceiver design for OFDM and receiver algorithms for MIMO communication channels over time-varying channels, with an emphasis on modern iterative turbo-style architectures, demonstrates how these important technologies can optimize future wireless systems
Download or read book Handbook of Mobile Broadcasting written by Borko Furht and published by CRC Press. This book was released on 2008-04-15 with total page 918 pages. Available in PDF, EPUB and Kindle. Book excerpt: Operators are introducing mobile television and digital video content services globally. The Handbook of Mobile Broadcasting addresses all aspects of these services, providing a comprehensive reference on DVB-H, DMB, ISDB-T, and MediaFLO. Featuring contributions from experts in the field, the text presents technical standards and distribution proto
Download or read book Advanced Interference Suppression Schemes for OFDM Systems written by K.M. Zahidul Islam and published by . This book was released on 2011 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: We also investigate computationally efficient reliable OFDM downlink signal detection algorithm in presence of relatively strong co-channel interference (CCI) from adjacent interfering base transceiver station (BTS). We propose and compare the performance of several per-subcarrier based CCI cancellation algorithms considering 1 and 2 receive antennas at the user terminal.
Download or read book Co channel Interference Cancellation for OFDM Systems Using the Expectation Maximization Algorithm written by Vikrant Venkateshwar Gunna Srinivasan and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Multicarrier Technologies for Future Radio Communication written by Hanna Bogucka and published by John Wiley & Sons. This book was released on 2017-07-12 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: A practical review of state-of-the-art non-contiguous multicarrier technologies that are revolutionizing how data is transmitted, received, and processed This book addresses the advantages and the limitations of modern multicarrier technologies and how to meet the challenges they pose using non-contiguous multicarrier technologies and novel algorithms that enhance spectral efficiency, interference robustness, and reception performance. It explores techniques using non-contiguous subcarriers which allow for flexible spectrum aggregation while achieving high spectral efficiency and flexible transmission and reception at lower OSI layers. These include non-contiguous orthogonal frequency division multiplexing (NC-OFDM), its enhanced version, non-contiguous filter-bank-based multicarrier (NC-FBMC), and generalized multicarrier. Following an overview of current multicarrier technologies for radio communication, the authors examine particular properties of these technologies that allow for more efficient usage within key directions of 5G. They examine the principles of NC-OFDM and discuss efficient transmitter and receiver design. They present the principles of FBMC modulation and discuss key challenges for FBMC communications while comparing performance results with traditional OFDM. They move on from there to a fascinating discussion of GMC modulation within which they clearly demonstrate how that technology encompasses all of the advantages of previously discussed techniques, as well as all imaginable multi- and single-carrier waveforms. Addresses the problems and limitations of current multicarrier technologies (OFDM) Describes innovative techniques using non-contiguous multicarrier waveforms as well as filter-band based and generalized multicarrier waveforms Provides a thorough review of the practical limitations and solutions for evolving and breakthrough 5G communication technologies Explores the future outlook for non-contiguous multicarrier technologies as regards their greater industrial realization, hardware practicality, and other challenges Advanced Multicarrier Technologies for Future Radio Communication: 5G and Beyondis an indispensable working resource fortelecommunication engineers, researchers and academics, as well as graduate and post-graduate students of telecommunications. At the same time, it provides a fascinating look at the shape of things to come for telecommunication industry executives, telecom operators, regulators, policy makers, and economists.
Download or read book Channel Estimation Algorithms for OFDM in Interference Scenarios written by Farah Zaarour and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The scarcity of the radio spectrum and the increasing demand on bandwidth makes it vital to optimize the spectrum use. While a maximum efficiency should be attained, a minimal interference level should be maintained. OFDM has been selected as the modulation scheme in several wireless standards. Channel estimation is a fundamental task in OFDM and it becomes even more challenging in the presence of interference. In this thesis, our aim is to propose channel estimation algorithms for OFDM systems in the presence of interference, where conventional channel estimators designed for OFDM fail. First, we consider the cognitive radio environment and propose a novel channel estimation framework for fast time-varying channels in OFDM with NBI. This is accomplished through an expectation maximization (EM) based algorithm. This formulation allows us to obtain a closed-form expression for the estimation of the noise power. In this thesis, we are particularly interested in a very recent scheme of superimposed pilots for OFDM (DNSP). DNSP assures interference-free pilots at the expense of data interference. Seen the modernity of DNSP, a suitable receiver has to be designed to cope with its design. We first propose a low-complexity interference canceler (IC) for slow time-varying channels with DNSP. The performance of the proposed IC is guaranteed when the channel estimation error is small. As another contribution, we extend the design of the approximated IC for DNSP so as to take the channel estimation errors into account. Finally, we consider robust channel estimation which can be viewed as one of the perspectives of this thesis.
Download or read book Wireless Communications over MIMO Channels written by Volker Kuhn and published by John Wiley & Sons. This book was released on 2006-07-11 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless Communications over MIMO Channels: Applications to CDMA and Multiple Antenna Systems covers both, state-of-the-art channel coding concepts and CDMA and multiple antenna systems, rarely found in other books on the subject. Furthermore, an information theoretical analysis of CDMA and SDMA systems illuminate ultimate limits and demonstrates the high potential of these concepts. Besides spatial multiplexing, the use of multiple transmit antennas in order to increase the link reliability by diversity concepts (space-time coding) is described. Another focus is the application of error control coding in mobile radio communications Accompanying appendices include: basic derivations, tables of frequently used channel models, chain rules for entropy and information, data processing theorem, basics of linear algebra, Householder reflection and Givens rotation, and the LLL algorithm for lattice reduction.
Download or read book Interference Mitigation Techniques in Cellular OFDM Systems written by and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parallel Computing written by Christian Bischof and published by IOS Press. This book was released on 2008 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt: ParCo2007 marks a quarter of a century of the international conferences on parallel computing that started in Berlin in 1983. The aim of the conference is to give an overview of the developments, applications and future trends in high-performance computing for various platforms.
Download or read book OFDM and MC CDMA for Broadband Multi User Communications WLANs and Broadcasting written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2005-01-28 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal frequency-division multiplexing (OFDM) is a method of digital modulation in which a signal is split into several narrowband channels at different frequencies. CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimising the use of available bandwidth. Multiplexing is sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end. Multi-Carrier (MC) CDMA is a combined technique of Direct Sequence (DS) CDMA (Code Division Multiple Access) and OFDM techniques. It applies spreading sequences in the frequency domain. Wireless communications has witnessed a tremendous growth during the past decade and further spectacular enabling technology advances are expected in an effort to render ubiquitous wireless connectivity a reality. This technical in-depth book is unique in its detailed exposure of OFDM, MIMO-OFDM and MC-CDMA. A further attraction of the joint treatment of these topics is that it allows the reader to view their design trade-offs in a comparative context. Divided into three main parts: Part I provides a detailed exposure of OFDM designed for employment in various applications Part II is another design alternative applicable in the context of OFDM systems where the channel quality fluctuations observed are averaged out with the aid of frequency-domain spreading codes, which leads to the concept of MC-CDMA Part III discusses how to employ multiple antennas at the base station for the sake of supporting multiple users in the uplink Portrays the entire body of knowledge currently available on OFDM Provides the first complete treatment of OFDM, MIMO(Multiple Input Multiple Output)-OFDM and MC-CDMA Considers the benefits of channel coding and space time coding in the context of various application examples and features numerous complete system design examples Converts the lessons of Shannon’s information theory into design principles applicable to practical wireless systems Combines the benefits of a textbook with a research monograph where the depth of discussions progressively increase throughout the book This all-encompassing self-contained treatment will appeal to researchers, postgraduate students and academics, practising research and development engineers working for wireless communications and computer networking companies and senior undergraduate students and technical managers.
