File Name: a comparative study of ldpc codes and convolutional codes in wimedia phy .zip
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The work in this paper can be broadly divided into three distinct parts. In first part of this work, a deterministic channel model is developed using the art of computer game technology. The developed system can compute the impulse response of an indoor environment. In the second part of the work, the designed channel model is extended to inherent antenna diversity.
Show all documents Therefore, the singular-value- finding algorithm may stop whenever the smallest singu- lar value is large enough to guarantee symbol recovery. On the other hand, in the modified scheme, there exists some op- timal choice of AZP length. Heuristically, if we slide a win- dow on the received block, there exists an optimal shift for the windowed sequence to capture most of the energy in the original sequence. This can be achieved by a simple search procedure. Advanced multi band modulation technology for underwater communication systems However, implementation details of OFDM can still perform significantly well due to tight throughput, wide propagation dispersion, and the associated inter-block interference IBIs in underwater acoustic channels. Such CP is replaced in ZP- OFDM by a ZP to solve the channel transmission zero problem and guarantee symbol recovery for any case of the channel zero locations [, ], and also to reduce the consumption of the guard interval power [6, 9, 11, 12].
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Nowak and O. Hundt and R.
Directory of Open Access Journals Sweden. Full Text Available A novel threshold computation method for pilot symbol assisted iterative channel estimation in OFDM systems is considered. As the bits are transmitted in packets, the proposed technique is based on calculating a particular threshold for each data packet in order to select the reliable decoder output symbols to improve the channel estimation performance. Iteratively , additional pilot symbols are established according to the threshold and the channel is re- estimated with the new pilots inserted to the known channel estimation pilot set. The proposed threshold calculation method for selecting additional pilots performs better than non- iterative channel estimation , no threshold and fixed threshold techniques in poor HF channel simulations. Full Text Available The application of the expectation-maximization EM algorithm to channel estimation results in a well-known iterative channel -and-symbol estimator ICSE. The EM-ICSE iterates between a symbol estimator based on the forward-backward recursion BCJR equalizer and a channel estimator , and may provide approximate maximum-likelihood blind or semiblind channel estimates.
Andrews, A. Ghosh, R. If we space OFDM symbols by gaps at least as long as the delay spread, then there will be no intersymbol interference However, there will still be interference within the symbol intrasymbol. Equalization and the DFT While using longer symbol timing means OFDM can avoid irreducible errors, still have interfering energy in band from multipath Received signal is the linear convolution of channel impulse response with transmitted signal. Y XkH k k Implication: If we can make the system behave like a circular convolution, equalization is trivial complex multiplication per FFT bin at the receiver. Cyclic Prefix Adding a cyclic prefix at transmitter leads to circular convolution Note that misaligned timing still results in a circular convolution, just time shifted Makes for phase shifts in FFT bins Correct that in a moment J.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Publications 8. Citations Highly Influential Citations 0.
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When | Find, read and cite all the research you need on ResearchGate. The comparison of convolutional codes and LDPC codes in WiMedia PHY is performed by considering different code rates and indoor Request Full-text Paper PDF.
This page intentionally left blank Reliable Communications for Short-range Wireless Systems Ensuring reliable communication is an important concern in short-range wireless communication systems with stringent quality of service requirements. Key characteristics of these systems, including data rate, communication range, channel profiles, network topologies, and power efficiency, are different from those in long-range systems. This comprehensive book classifies short-range wireless technologies as high and low data rate systems.
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