Download or read book Channel Estimation for the Superimposed Training Scheme in OFDM Systems Without Cyclic Prefix written by 楊易洵 and published by . This book was released on 2008 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Carrier Frequency Offset and Channel Estimation with Superimposed Training Sequence in OFDM Systems written by Chia-Hua Chang and published by . This book was released on 2008 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adaptive Channel Estimation of OFDM Systems Using the Cyclic Prefix with an RLS Based Algorithm in Mobile Channels written by Ziya Dereboylu and published by . This book was released on 2005 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Implementation of Channel Estimation Algorithms in OFDM written by Navdeep Bansal and published by LAP Lambert Academic Publishing. This book was released on 2014-11-01 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal Frequency Division Multiplexing (OFDM) is a very potential technique for transmitting high bit rate data over indoor and outdoor wireless communication channels with high bandwidth efficiency and robustness to multipath delay. OFDM is a multichannel modulation that divides a given channel into many parallel sub-channels or subcarriers, so that multiple symbols are sent in parallel. The first multichannel modulation systems appeared in the 1950's as military radio links, best characterized as frequency-division multiplexed systems. The first OFDM schemes were presented by Chang and Saltsburg, in which actual use/ practicability of OFDM was limited. However, later on the OFDM was made more practical through work describe in the article uses Discrete Fourier transform (DFT) with a cyclic prefix. The DFT implemented with a Fast Fourier Transform (FFT)) and the cyclic prefix have made OFDM both practical and attractive to the radio link designer. A similar multichannel modulation scheme, Discrete Multi-Tone (DMT) modulation, has been developed for static channels such as the digital subscriber loop.
Download or read book Channel Equalization and Phase Estimation for Reduced guard Interval CO OFDM Systems written by Qunbi Zhuge and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reduced-guard-interval (RGI) coherent optical (CO) orthogonal frequency-division multiplexing (OFDM) is a potential candidate for next generation 100G beyond optical transports, attributed to its advantages such as high spectral efficiency and high tolerance to optical channel impairments. First of all, we review the coherent optical systems with an emphasis on CO-OFDM systems as well as the optical channel impairments and the general digital signal processing techniques to combat them. This work focuses on the channel equalization and phase estimation of RGI CO-OFDM systems. We first propose a novel equalization scheme based on the equalization structure of RGI CO-OFDM to reduce the cyclic prefix overhead to zero. Then we show that intra-channel nonlinearities should be considered when designing the training symbols for channel estimation. Afterwards, we propose and analyze the phenomenon of dispersion-enhanced phase noise (DEPN) caused by the interaction ...
Download or read book Channel Estimation written by Shazib Naveed and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: With rapid growth of digital communication in recent years, the need for high speed data transmission is increased. Moreover, future wireless systems are expected to support a wide range of services which includes video, data and voice. OFDM is a promising candidate for achieving high data rates in mobile environment, due to its resistance to ISI, which is a common problem found in high speed data communication. In OFDM, modulation may be differential or coherent. When using differential modulation there is no need for a channel estimate but its performance is inferior to the coherent system. Coherent modulation requires the channel estimation which gives better performance but with relatively more complex receiver structure. Training Symbol Assisted Modulation is used to achieve reliable channel estimates by transmitting Training along with data symbols. In this thesis, Shazib Naveed has analyzed different channel estimation patterns in terms of BER and propose a new scheme for transmitting Training symbols in wireless OFDM systems. Author has also proposed an adaptive scheme of channel estimation in wireless OFDM systems, which track the multi-path fading channel.
Download or read book Proceedings of the International Computer Conference 2006 on Wavelet Active Media Technology and Information Processing written by Jian Ping Li and published by World Scientific. This book was released on 2006-01-01 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 sound recording written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Channel Estimation for Capacity Maximization in Ofdm Systems written by Engr. Asghar Khan and published by LAP Lambert Academic Publishing. This book was released on 2011-02 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: The channel estimation techniques based on pilot arrangement for OFDM systems are investigated in this book. The channel estimation based on block type pilot arrangement is performed by sending pilots at every sub-channel and using this estimation for a fixed number of symbols. The channel for block-type pilot arrangement is estimated by Least Square (LS) or Minimum Mean-Square (MMSE) estimators. The channel estimation based on comb type pilot arrangement is performed by inserting pilot tones into each OFDM symbol. The channel estimation based on comb type pilot arrangement is studied and implemented through different algorithms for both estimating and interpolating the channel. The channel interpolation is done using linear interpolation, second order interpolation, low-pass interpolation, spline cubic interpolation and time domain interpolation. We have also implemented decision feedback equalizer for all sub-channels to reduce the bit error rate. We have compared the performances of all schemes by measuring bit error rate with 16QAM, 32QAM, 64QAM, 128QAM and 256QAM as modulation schemes and Rayleigh as channel model.
Download or read book Journal of Communications and Networks written by and published by . This book was released on 2009 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design of Channel Estimation and Equalization for OFDM Systems written by Ali Salah Mahdi and published by LAP Lambert Academic Publishing. This book was released on 2015-01-20 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal Frequency Division Multiplexing (OFDM) system is one of the multicarrier techniques which is robust against Inter-symbol-Interference, multipath fading and very easy to apply in transmitters by using inverse fast Fourier transform IFFT and at the receivers by using fast Fourier transform FFT. In a communication system, channel estimation is very important issue for the data detection. In coherent detection, one of the popular techniques is to use pilot tones as a reference signal in OFDM symbols. In the comb-type pilot tones insertion, pilot tones are inserted into each OFDM symbols, but inserting a large number of pilot tones will lead to channel capacity reduction or bandwidth expansion [1-2]. In this work, to overcome this transmission loss, a modified least square (ModLS) algorithm for fast time varying wireless channel at comb-type pilot arrangement in QAM signals for OFDM system is proposed. The simulation results obtained from the proposed algorithm showed a good performance in noisy wireless channels. In addition, it has been compared with least square (LS) algorithm in different signal to noise ratios and different channel tabs.
Download or read book Wavelet Active Media Technology and Information Processing 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 Superimposed Training Aided Channel Estimation for Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing Systems Over High Mobility Environment written by Han Zhang and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Superimposed Training-Aided Channel Estimation for Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing Systems over High-Mobility Environment.
Download or read book Channel Estimation in Multicarrier Communication Systems written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The data rate and spectrum efficiency of wireless mobile communications have been significantly improved over the last decade or so. Recently, the advanced systems such as 3GPP LTE and terrestrial digital TV broadcasting have been sophisticatedly developed using OFDM and CDMA technology. In general, most mobile communication systems transmit bits of information in the radio space to the receiver. The radio channels in mobile radio systems are usually multipath fading channels, which cause inter-symbol interference (ISI) in the received signal. To remove ISI from the signal, there is a need of strong equalizer which requires knowledge on the channel impulse response (CIR). This is primarily provided by a separate channel estimator. Usually the channel estimation is based on the known sequence of bits, which is unique for a certain transmitter and which is repeated in every transmission burst. Thus, the channel estimator is able to estimate CIR for each burst separately by exploiting the known transmitted bits and the corresponding received samples. In this thesis we investigate and compare various efficient channel estimation schemes for OFDM systems which can also be extended to MC DS-CDMA systems. The channel estimation can be performed by either inserting pilot tones into all subcarriers of OFDM symbols with a specific period or inserting pilot tones into each OFDM symbol. Two major types of pilot arrangement such as block type and comb type pilot have been focused employing Least Square Error (LSE) and Minimum Mean Square Error (MMSE) channel estimators. Block type pilot sub-carriers is especially suitable for slow-fading radio channels whereas comb type pilots provide better resistance to fast fading channels. Also comb type pilot arrangement is sensitive to frequency selectivity when comparing to block type arrangement. However, there is another supervised technique called Implicit Training (IT) based channel estimation which exploits the first order statistics i.
Download or read book STUDY OF CHANNEL ESTIMATION FO written by Wen Zhou and published by Open Dissertation Press. This book was released on 2017-01-26 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "A Study of Channel Estimation for OFDM Systems and System Capacity for MIMO-OFDM Systems" by Wen, Zhou, 周雯, 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_b4555585 Subjects: Orthogonal frequency division multiplexing - Mathematical models MIMO systems - Mathematical models
Download or read book Channel Estimation for OFDM Systems with Transmitter Diversity written by Igor A. Tolochko and published by . This book was released on 2005 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
