In this paper, a method for simultaneously demodulating and estimating the parameters of a number of convolutional coded communication signals incident on an antenna array is presented, The method has the potential to...
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In this paper, a method for simultaneously demodulating and estimating the parameters of a number of convolutional coded communication signals incident on an antenna array is presented, The method has the potential to increase the throughput of current multiple-access channel systems, e.g., satellite communications and digital mobile cellular phones, by using an antenna array, The contribution of this paper is the use of sequence estimation combined jointly with parameter estimation in array processing problems, A hidden Markov-model-based technique, the segmental k-means algorithm, is applied to the problem, This algorithm is an iterative procedure with two steps per iteration, The first step involves computing the most likely state sequence for each of the signals (demodulating the signals) given estimates of the signals' parameters, The second step refines the parameter estimates using the signals' mostly likely state sequence estimates, In the simulations presented, it is shown that a significant improvement in the accuracy of the demodulated signals and in the estimation of the signals' angle of arrivals is obtained when compared to a deterministic maximum likelihood estimation method.
A noncoherent multiple antenna coded communication system over both block fading and time-selective flat fading Rayleigh channel is considered. Several iterative decoding strategies consisting of pilot symbol assisted...
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A noncoherent multiple antenna coded communication system over both block fading and time-selective flat fading Rayleigh channel is considered. Several iterative decoding strategies consisting of pilot symbol assisted demodulation and turbo decoding are proposed. It is shown that, at a system rate of 0.9 bits per channel use, the SNR required to achieve a BER of 10(-4) is only about 2 dB from the imperfect CSI capacity lower bound. The channel estimation error variance is demonstrated to be close to the theoretical limit set by the Modified Cramer-Rao bound. The simulation results coincide with the trends dictated by recent information-theoretic analysis and demonstrate the effect that inaccuracy of the channel estimation has on the performance of the iterative decoding scheme. Copyright (c) 2007 John Wiley & Sons, Ltd.
This paper studies the impact of using automatic data-layout techniques on the process of coding the well-known multigrid MG NAS parallel benchmark. We describe the sequential problem in detail, and discuss the parall...
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ISBN:
(纸本)9780769543284
This paper studies the impact of using automatic data-layout techniques on the process of coding the well-known multigrid MG NAS parallel benchmark. We describe the sequential problem in detail, and discuss the parallel version and its optimizations. Then, we implement the parallel algorithm using Hitmap, a highly-efficient modular library for hierarchical tiling and mapping of arrays. We describe how to use the library plug-in system to add a new data-layout module that encapsulates a generalization of the data-alignment policy of the MG benchmark. The module system applies this policy to automatically adapt the data distribution and communication code to any grain level. The impact of using these techniques is qualitatively and quantitatively described in terms of development effort and performance. Our results show that it is possible to introduce flexible automatic data-layout techniques in current parallel compiler technology, without sacrificing performance.
Reducing Impulse noise is a very active research area in communication systems. This paper presents a digital smear-desmear technique (SDT) applied to data transmission over band limited channels. A generalized set of...
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ISBN:
(纸本)9781467318808
Reducing Impulse noise is a very active research area in communication systems. This paper presents a digital smear-desmear technique (SDT) applied to data transmission over band limited channels. A generalized set of Alter design criteria based on minimizing the average bit error probability is introduced. The design criteria were applied to a practical digital filter implementing SDT techniques. The SDT is simulated and combined with coded communication systems for high data transmission rate. Simulation results show that the SDT yields a significant improvement in bit error rates for coded systems subject to impulse noise, relative to the systems with no SDT. The technique also completely removes the error floor caused by the impulse noise.
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