Download or read book Performance Analysis of Adaptive Transmission Aided by Long Range Channel Prediction for Realistic Single and Multi carrier Mobile Radio Channels written by Tung-Sheng Yang and published by . This book was released on 2004 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: wireless communications, physical channel modeling, adaptive modulation, channel prediction, OFDM.

Download or read book Zu Wilhelm Weischedel written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance Analysis of Reliable Adaptive Transmission for Mobile Radio Slow Frequency Hopping Channels Aided by Long Range Prediction written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to correlated fading in frequency hopping (FH) wireless communication systems, it is possible to predict the future channel state information (CSI) for one frequency based on the channel observations of other frequencies. As a result, the performance of slow FH systems can be improved by utilizing adaptive transmission techniques. We propose the optimal Minimum Mean Square Error (MMSE) Long Range Prediction algorithm for slow FH systems that employ coherent detection. A recursive autocorrelation update method and a simplified prediction algorithm are explored to reduce the complexity. Statistical model of the prediction accuracy is developed and used in the design of the reliable adaptive transmission systems. We investigate the performance of adaptive transmission for high-speed data transmission in SFH systems based on the proposed Long Range Prediction algorithms. For slow frequency hopping communications in the presence of partial-band interference, we propose to employ adaptive transmitter frequency diversity and adaptive modulation to mitigate the effects of partial-band interference and fading. Both standard Jakes model and realistic physical model are used to test the performance. Analysis and simulation results show that significant performance gains can be achieved relative to non-adaptive methods.

Download or read book Single and Multicarrier Adaptive Transmission Systems with Long Range Prediction Aided by Noise Reduction written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive transmission methods have evolved as one of the key enabling technologies to meet the increasing demand for high-speed wireless data access services. In this dissertation, we address several adaptive transmission systems and techniques required for their implementation. First, we focus on multicarrier code-division multiple access (MC-CDMA) system with adaptive frequency hopping (AFH). A suboptimal water-filling (WF) channel allocation algorithm was previously proposed for the reverse link of this system. To overcome the limitations of the WF algorithm in the presence of fading-induced near-far problem, a new allocation algorithm is proposed and demonstrated to improve performance when the conventional matched filter (MF) receiver is employed. Moreover, the allocation methods are extended to accommodate multiuser detectors (MUDs) at the receiver for MC-CDMA system with AFH. It is demonstrated that the combination of the improved allocation algorithm and the linear MUDs is very efficient in mitigating fading and multi-access interference (MAI) for realistic mobile radio channels with correlated subcarriers, channel state information (CSI) mismatch, and imperfect power control. Numerical results show that the proposed adaptive transmission method has much greater system capacity than conventional non-adaptive MC direct-sequence (DS)-CDMA system. Second, the adaptive modulation (AM) system is investigated. To ensure high spectral efficiency (SE) for AM systems, the CSI needs to be predicted to compensate for the feedback and data processing delay and system constraints. The long-range prediction (LRP) method achieves high prediction accuracy at practical predication ranges when the signal-to-noise ratio (SNR) of the observations is sufficiently high. However, its accuracy degrades severely at low and medium SNR. Hence, the noise reduction (NR) techniques are required for the LRP to achieve the desired prediction accuracy. A novel data-aided noise reduction (DA.

Download or read book Long Range Fading Prediction and Realistic Physical Modeling to Enable Adaptive Transmission for Mobile Radio Networks written by and published by . This book was released on 2005 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The feasibility of adaptive transmission enabled by Long Range Fading Prediction (LRP) was investigated for rapidly varying fading channels encountered in peer-to-peer mobile communication systems. The LRP algorithms were tested using the standard Jakes model and the realistic physical model developed by the Principal Investigators. This research was an interdisciplinary effort in communication theory, physics, and signal processing. Correlated fading was exploited in the development of the LRP algorithm to enable adaptive modulation for a Frequency Hopping Spread Spectrum (FH/SS) mobile radio channel. Adaptive frequency diversity transmission for FH systems with partial band interference also was explored. Significant performance gains were demonstrated relative to non-adaptive methods. Efficient channel loading for wireless Adaptive Orthogonal Frequency Division Multiplexing (AOFDM) systems aided by robust LRP was investigated and reduced feedback techniques were developed. The bit rates approaching those of AOFDM with perfect knowledge of fading conditions were achieved. Several linear and nonlinear Multi-Access Interference (MAI) mitigation and frequency diversity combining transmitter precoding methods aided by the LRP were developed for the downlink of the Direct Sequence Spread Spectrum (DS/SS) systems. The proposed techniques were shown to improve upon previously proposed precoding and detection methods while providing the desired performance/complexity trade-off.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Transmission and Channel Modeling for Frequency Hopping Communications written by and published by . This book was released on 2009 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project focused on design of adaptive transmission methods enabled by the long range fading prediction (LRP) for several mobile radio systems. First, a new improved allocation algorithm was proposed for multicarrier code-division multiple access (MC-CDMA) system with adaptive frequency hopping. When combined with multiuser detection, the proposed system is very efficient in mitigating the fading and multi-access interference for realistic mobile radio channels.

Download or read book Single and Multicarrier Adaptive Transmission Systems with Long range Prediction Aided by Noise Reduction written by Tao Jia and published by . This book was released on 2008 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: noise reduction, multicarrier transmission, long-range fading prediction, adaptive modulation.

Download or read book Realizing the Potential of Adaptive Transmission Techniques Through Long Range Prediction for Rapidly Time variant Fading Mobile Radio Channels written by Shengquan Hu and published by . This book was released on 2000 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analytical Evaluation of Adaptive Transmission Protocols for Markov Models of Channels with Fading and Moderate Shadowing written by Sneha L. Kottapalli and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Adaptive transmission protocols are often employed to communicate over wireless channels with fading and other time-varying propagation losses. The protocols compensate for the propagation losses and maintain high throughput by adjusting transmission parameters in response to the channel variations. Performance evaluations for practical adaptive transmission protocols typically require simulation of both the time-varying processes and the procedure by which the protocol derives information about the channel quality. In this thesis, we develop an analytical method to evaluate the performance of two practical protocols, an adaptive coding protocol and an adaptive modulation and coding protocol, which rely on statistics derived from the demodulation process. Our method for performance analysis avoids the need for simulations of the adaptive protocols and the derivation of statistics that are used for adaptation; furthermore, our approach avoids the simulation of the time-varying channel.

Download or read book Frequency domain Equalization of Single Carrier Transmissions Over Doubly Selective Channels written by Hong Liu and published by . This book was released on 2007 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Wireless communication systems targeting at broadband and mobile transmissions commonly face the challenge of fading channels that are both time and frequency selective. Therefore, design of effective equalization and estimation algorithms for such channels becomes a fundamental problem. Although multi-carrier transmissions demonstrate prominent potential to combat doubly selective fading, several factors may retard their applications, such as: high peak-to-average power ratio, sensitivity to phase noise, etc. Meanwhile, single-carrier transmission is a conventional approach and has important applications, such as HDTV broadcasting, underwater acoustic communication. In this dissertation, we focus on receiver design for single-carrier transmissions. Our goal is to design and develop a group of channel estimation and equalization algorithms in the frequency-domain, which enable high performance and low complexity reception of single-carrier transmissions through doubly selective channels. For single-carrier transmissions over moderately fast fading channels with long-delay spread, we present an improved iterative frequency-domain equalization (IFDE) algorithm based on soft-interference-cancellation (SIC) and propose a novel adaptive frequency-domain channel estimation (AFDCE) based on soft-input Kalman filter, where soft information feedback from the IFDE can be exploited in the channel estimator. Simulation results show that, compared to other existing schemes, the proposed scheme offers lower MSE in channel prediction, lower BER after decoding, and robustness to non-stationary channels. We extend the IFDE/AFDCE scheme to accommodate the application of digital television (DTV) signal reception. Compared with the traditional joint decision feedback equalization (DFE) /decoding plus frequency-domain least-mean-square (FDLMS) channel estimation approach, the proposed scheme achieves better performance at a fraction of the implementation cost. For very fast fading large-delay-spread channels, traditional FDE methods fail, because channel variation within a FFT block induces significant off-main-diagonal coefficients in the frequency domain. To conquer the problem, we apply Doppler channel shortening to shape the energy distribution of those coefficients and derive a pilot-aided MMSE estimator to estimate them for SIC. We also propose a novel IFDE by leveraging both the sparse structure of shortened channel and finite-alphabet property of transmitted symbols. Numerical results show that the proposed scheme has advantages over the well-known FIR-MMSE-DFE/RLS-CE scheme in both performance and complexity.

Download or read book Performance Evaluation of Mobile Radio Networks Over Fading Channels System and Link level Perspectives written by Mahmoud H. Ismail and published by . This book was released on 2006 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance evaluation studies constitute a considerable portion of the wireless communications literature. The importance of these studies stems from the fact that they provide system designers with feedback on the quality of their designs and hence, an opportunity for enhancements and refinements before actual deployment.

Download or read book Channel Adaptive Transmission of Big Data written by Wen-Jing Wang and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate the statistics of transmission time of wireless systems employing adaptive transmission. Unlike traditional transmission systems where the transmission time of a fixed amount of data is typically regarded as a constant, the transmission time with adaptive transmission systems becomes a random variable, as the transmission rate varies with the fading channel condition. To facilitate the design and optimization of wireless transmission schemes, we present an analytical framework to determine statistical characterizations for the transmission time with adaptive transmission. In particular, we derive the exact statistics of transmission time over block fading channels. The probability mass function (PMF) and cumulative distribution function (CDF) of transmission time are obtained for both slow and fast fading scenarios. We further extend our analysis to Markov channels, where the transmission time becomes a sequence of exponentially distributed random-length time slots. Analytical expression for the probability density function (PDF) of transmission time is derived for both fast and slow fading scenarios. Since the energy consumption can be characterized by the product of power consumption and transmission time, we also evaluate the energy consumption for wireless systems with adaptive transmission. Cognitive radio communication can opportunistically access underutilized spectrum for emerging wireless applications. With interweave cognitive implementation, a secondary user (SU) transmits only if a primary user does not occupy the channel and waits for transmission otherwise. Therefore, secondary packet transmission involves both transmission and waiting periods. The resulting extended delivery time (EDT) is critical to the throughput analysis of secondary system. With the statistical results of transmission time, we derive the PDF of EDT considering random-length SU transmission and waiting periods for continuous spectrum sensing and semi-periodic spectrum sensing. Taking spectrum sensing errors into account, we propose a discrete Markov chain modeling slotted secondary transmission coupled with periodic spectrum sensing. Markov modeling is applied to energy efficiency optimization and queuing performance evaluation.

Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 2240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multi Carrier and Spread Spectrum Systems written by K. Fazel and published by John Wiley & Sons. This book was released on 2004-02-06 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frequency spectrum is a limited and valuable resource for wireless communications. A good example can be observed among network operators in Europe for the prices to pay for UMTS-frequency bands. Therefore, the first goal when designing future wireless communication systems (e.g. 4G - fourth generation) has to be the increase in spectral efficiency. The development in digital communications in the past years has enabled efficient modulation and coding techniques for robust and spectral efficient data, speech, audio and video transmission. These are the multi-carrier modulation (e.g. OFDM) and the spread spectrum technique (e.g. DS-CDMA), where OFDM was chosen for broadcast applications (DVB, DAB) as well as for broadband wireless indoor standards (ETSI HIPERLAN-II, IEEE-802.11) and the DS-CDMA was selected in mobile communications (IS-95, third generation mobile radio systems world wide, UMTS/IMT 2000). Since 1993 various combinations of multi-carrier (MC) modulation and the spread spectrum (SS) technique have been introduced and the field of MC-SS communications has become an independent and important research topic with increasing activities. New application fields have been proposed such as high rate cellular mobile, high rate wireless indoor and LMDS. It has been shown that MC-SS offers the high spectral efficiency, robustness and flexibility that is required for the next generation systems. Meanwhile, different alternative hybrid schemes such as OFDM/OFDMA, MC-TDMA, etc. have been deeply analysed and adopted in different international standards (ETSI-BRAN, IEEE-802 & MMAC). Multi-Carrier & Spread-Spectrum: Analysis of Hybrid Air Interfaces draws together all of the above mentioned hybrid schemes therefore providing a greatly needed resource for system engineers, telecommunication designers and researchers in order to enable them to develop, build and deploy several schemes based on MC-transmission for the next generation systems (which will be an integration of broadband multimedia services covering both 4G mobile and fixed wireless systems). * Offers a complete treatment of multi-carrier, spread-spectrum (SS) and time division multiplexing (TDM) techniques * Provides an in-depth insight into hybrid multiple access techniques based on multi-carrier (MC) transmission * Presents numerous hybrid multiple access and air interface architectures including OFDM/CDMA, MC-CDMA, MC-DS-CDMA and MT-CDMA * Covers new techniques such as space-time coding and software radio Telecommunications engineers, hardware & software system designers and researchers as well as students, lecturers and technicians will all find this an invaluable addition to their bookshelf.

Download or read book Mobile Fading Channels written by Matthias Pätzold and published by Wiley. This book was released on 2002-04-01 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: All relevant components of a mobile radio system, from digital modulation techniques over channel coding through to network aspects, are determined by the propagation characteristics of the channel. Therefore, a precise knowledge of mobile radio channels is crucial for the development, evaluation and test of current and future mobile radio communication systems. This volume deals with the modelling, analysis, and simulation of mobile fading channels and provides a fundamental understanding of many issues that are currently being investigated in the area of mobile fading channel modelling. The author strongly emphasises the detailed derivation of the presented channel models and conveys a high degree of mathematical unity to the reader. * Introduces the fundamentals of stochastic and deterministic channel models * Features the modelling and simulation of frequency-nonselective fading channels (Rayleigh channels, Rice channels, generalized Rice channels, Nakagami channels, various types of Suzuki channels, classical and modified Loo model) * Presents the modelling and simulation of frequency-selective fading channels (WSSUS models, DGUS models, channel models according to COST 207) * Discusses the methods used for the design and realization of efficient channel simulators * Examines the design, realization, and analysis of fast channel simulators * Includes MATLAB? programs for the evaluation and simulation of mobile fading channels MATLAB? is a registered trademark of The MathWorks, Inc. Telecommunication engineers, computer scientists, and physicists will all find this text both informative and instructive. It is also be an indispensable reference for postgraduate and senior undergraduate students of telecommunication and electrical engineering.

Download or read book Multi carrier Transmission in a Mobile Radio Environment written by Ibrahim Awad Zamil Qatawneh and published by . This book was released on 1994 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Utilization of the limited resource of the frequency spectrum. The prospect of employing Orthogonal Frequency Division Multiplexing as a multi-carrier technique in order to support high transmission rate is therefore investigated. In particular, there is an interest in using OFDM in a mobile radio environment. The transmission of blocks of bits in parallel on separate carriers improves the bit error rate at reception because the effect of fading tends to average out. Using a commercial software simulator both transmitter and receiver are implemented and the performance of the overall system is assessed through bit error rate measurements. Quadrature Phase Shift Keying and Offset Quadrature Phase Shift Keying are analyzed in the presence of Additive White Gaussian Noise and Rayleigh fading. Further results related to loss of synchronization in timing recovery circuit and phase offsets in the modulators are also presented.