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AFRICON Conference

作者： C. Mitchell F. Swarts F. Aghdasi Department of Electrical Engineering University of the Witwatersrand South Africa Department of Electrical Engineering University of Pretoria South Africa

The use of an adaptive forward error control coding scheme is investigated on Rayleigh fading channels typically encountered in mobile communications systems. A predictive algorithm is used to estimate the fading intensity on the channel and this estimate is used to predict the code parameters. It is found that the use of the proposed scheme leads to an improvement in both the bit error rate performance and the throughput of the system.

关键词： adaptive coding Fading Programmable control adaptive control Error correction Mobile communication Prediction algorithms Rayleigh channels Bit error rate Throughput

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adaptive coding for fading channels using outdated channel estimates

Adaptive coding for fading channels using outdated channel e...

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IEEE Conference on Vehicular Technology (VTC)

作者： D.L. Goeckel Electrical and Computer Engineering Department University of Massachusetts Amherst MA USA

The development of adaptive trellis coded modulation schemes for communication systems operating over time-varying Rayleigh fading channels is considered. If the system employs a single outdated noiseless channel estimate and is able to achieve perfect interleaving of the coded symbols, substantial throughput gains are observed over non-adaptive trellis coded modulation schemes for systems with low user mobility. Next, the effect of noise in the channel estimates is shown to be an important consideration, even at the relatively high signal-to-noise ratios considered here. Finally, a bound to the pairwise error probability between two paths in the trellis of the adaptive scheme is derived analytically for the case where the coded symbols are imperfectly interleaved; this result suggests that adaptive signaling may be a strong candidate for systems operating in an environment that has limited diversity available.

关键词： adaptive coding Fading Time varying systems Channel estimation Frequency estimation Rayleigh channels Modulation coding Data communication Interleaved codes Throughput

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adaptive coding in direct-sequence spread-spectrum systems for channels with time-varying propagation losses

Adaptive coding in direct-sequence spread-spectrum systems f...

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MILCOM, Military Communications Conference

作者： M.B. Pursley T.C. Royster Clemson University Clemson SC USA

High-rate direct sequence spread spectrum with error-control coding has been shown to provide high data rates even in the presence of interference, which makes it attractive for inclusion in an adaptive transmission system. In this paper, we evaluate the performance of high-rate waveforms that use binary antipodal modulation, M-ary orthogonal modulation, or M-ary biorthogonal modulation. We demonstrate how to apply channel capacity results and receiver statistics to select appropriate transmission parameters. A power adjustment protocol that attempts to minimize the transmitted power based on feedback from the receiver is described and evaluated. An adaptive coding protocol is presented, and its performance is compared with that of ideal adaptive protocols that are given perfect channel state information

关键词： adaptive coding Spread spectrum communication Time varying systems Propagation losses Protocols Interference adaptive systems Biorthogonal modulation Channel capacity Statistics

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adaptive coding for pilot symbol assisted modulation without feedback

Adaptive coding for pilot symbol assisted modulation without...

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Asilomar Conference on Signals, Systems & Computers

作者： M. Medard I. Abou-Faycal U. Madhow Laboratory for Information and Decision Systems Massachusetts Institute of Technology USA Electrical and Computer Engineering Department University of California Santa Barbara USA

We show that pilot symbol assisted modulation (PSAM) schemes can be improved by adapting the coded modulation strategy at the sender to the quality of the channel measurement at the receiver, without requiring any channel feedback from the receiver. The transmitter employs interleaved codes, with data symbols coded according to their distance from the nearest pilot symbols. The performance benefits from this approach are quantified in the context of binary signaling over time-varying Rayleigh fading channels described by a Gauss-Markov model. The spacing of the pilot symbols is optimized to maximize the mutual information between input and output in the preceding setting. Causal and non-causal channel estimators of varying complexity and delay are considered. It is shown that, by appropriate optimization for the spacing between consecutive pilot symbols, the adaptive coding techniques proposed can yield up to 30% improvement in achievable rate, without any feedback from the receiver to the sender.

关键词： adaptive coding Modulation coding Feedback Delay estimation Transmitters Interleaved codes Fading Gaussian channels Context modeling Mutual information

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adaptive coding for OFDM based systems using generalized concatenated codes

Adaptive coding for OFDM based systems using generalized con...

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IEEE Conference on Vehicular Technology (VTC)

作者： O. Al-Askary L. Sidiropoulos L. Kunz C. Vouzas C. Nassif Radio Communication Systems Stockholm Sweden

Orthogonal frequency division multiplexing (OFDM) is considered to be a promising candidate for future high-speed wireless communication systems. We present an adaptive coding scheme for OFDM based systems using generalized concatenated codes. We study the performance of HIPERLAN/2 after encoding with the proposed coding scheme and compare it to the standard convolutional coding scheme currently used. The criterion of our study is the optimization of the throughput. Through the adaptive scheme, we propose a modulation selection based on the average quality of the channel, and a code assigning method for the different sub-channels that adapts to the channel conditions. We argue that the proposed scheme protects the information better than the ones in conventional systems, since the latter do not take advantage of the individual sub-channel condition. Our simulations show that a lower packet error rate can be accomplished for even higher throughput.

关键词： adaptive coding Concatenated codes OFDM modulation Modulation coding Quadrature amplitude modulation Physical layer Convolutional codes Error correction codes Telecommunication standards Convolution

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adaptive coding based on a new slice type in surveillance systems

Adaptive coding based on a new slice type in surveillance sy...

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International Colloquium on Signal Processing & Its Applications, CSPA

作者： Li Muchen Xin Jin Satoshi Goto Graduate School of Information Production and System Waseda University 2-7 Hibikino Kitakyushu 808-0135 Japan Graduate School of Information Production and System Waseda University Kitakyushu Japan

In surveillance systems, low bit rate video coding is necessary to reduce the storage and bandwidth consumption, especially for high definition video coding. In [1], we proposed an adaptive coding method to code the active regions with traditional slices and background with the proposed S slice respectively. The S slice contains less syntax elements than the conventional P slice. This paper further analyzes the influence factors to the S slice coding. Moreover, a control module is proposed to enable the S slice coding and to find the best partition pattern between active regions and background that could get the most bit reduction [3], [4].

关键词： adaptive coding Encoding Noise level Noise Bit rate Syntactics Testing

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adaptive coding rate and processing gain control for cellular DS/CDMA systems

Adaptive coding rate and processing gain control for cellula...

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International Conference on Universal Personal Communications

作者： S. Abeta S. Sampei N. Morinaga Faculty of Engineering Osaka University Suita Osaka Japan

This paper proposes an adaptive control scheme for processing gain and coding rate to achieve equivalent fast power control for high quality and high bit rate up-link cellular DS/CDMA systems. The proposed method employs a soft power control that has an upper and a lower threshold for the non-power control region to suppress adjacent cell interference, and an adaptive control for coding rate and processing gain to offset the C/I degradation due to the soft power control as well as to improve the BER performance. The results show that the proposed system can achieve 5 times or more system capacity than the conventional one.

关键词： adaptive coding Gain control Power control adaptive control Bit rate Multiaccess communication Interference suppression Performance gain Degradation Bit error rate

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adaptive modulation and coding (AMC) for bit-interleaved coded OFDM (BIC-OFDM)

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第7期5卷 1685-1694页

作者： Song, Kee-Bong Ekbal, Amal Chung, Seong Taek Cioffi, John M. Stanford Univ Dept Elect Engn Stanford CA 94305 USA

This paper proposes adaptive modulation and coding (AMC) as a method for the bit-interleaved coded OFDM (BIC-OFDM) packet transmission. Following a pair-wise error probability (PEP) analysis of AMC-BIC-OFDM in a slowly fading frequency selective channel, AMC scheme maximizes the total rate by optimally selecting the code and efficiently allocating rate and power over the frequency band. The proposed method improves upon the performance of uniform rate and power allocation scheme by 6.5 to 10 dB.

关键词： BICM adaptive coding adaptive modulation AMC rate and power allocation coded OFDM BICM capacity

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Research on Multimodal Data Fusion Based on Optimal adaptive coding

Research on Multimodal Data Fusion Based on Optimal Adaptive...

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Artificial Intelligence and Computer Engineering (ICAICE), International Conference on

作者： Yanhong Ma Yijie Qin Hong Zhang Kun Jiang State Grid Gansu Electric Power Company Lanzhou Gansu China School of Computer & Communication Lanzhou University of Technology Lanzhou Gansu China Changzhou Xingyu Automotive Lighting Systems Co. Ltd

ISBN: (数字)9798331528911

ISBN: (纸本)9798331528928

In order to solve the problems of low accuracy and poor robustness of existing multimodal data fusion models, this paper proposes a multimodal data fusion model based on adaptive coding. The model maps different modal data into the same subspace through LSTM, and adaptively learns the weights of different modal data, which helps the model to more accurately use the information of each modal data. To fully explore the interaction information among multimodal data and improve the accuracy of the model by extracting consistency and complementary features from multimodal data using a Transformer-based encoder. The uncertainty of the prediction distribution is quantified by an improved loss function to improve the anti-interference ability of the model. Experimentally evaluated on two publicly available datasets, CMU-MOSI and CMU-MOSEI, the results show that the model performs better.

关键词： Adaptation models Uncertainty Computational modeling Data integration Predictive models Feature extraction Transformers Data models Robustness adaptive coding

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On-board processing adaptive coding and modulation for regenerative satellite systems

On-board processing adaptive coding and modulation for regen...

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National Doctoral Academic Forum on Information and Communications Technology 2013

作者： Yongbin Wang Hong Ji Yi Li Beijing University of Posts and Telecommunications China

ISBN: (纸本)9781632660268

For the widely coverage of satellite beam, the dominated weather-caused attenuation on Ka-band causes the asymmetric fading of satellite uplink and downlink. The widely recognized adaptive coding and modulation (ACM), a significant fading mitigation technique in satellite communication systems, mainly focuses on improving the downlink spectrum efficiency. However, the uplink spectrum efficiency is always impaired when downlink channel condition is poor. In this paper, we propose a novel ACM scheme for geostationary (GEO) regenerative satellite systems, on which the on-board processing is based. To be more practical, two transfer modes: Transparent-transfer and Regenerative-transfer are designed. Nevertheless, regenerative transfer mode would result in data overflow on the satellite in the case of the selected uplink modulation and coding order is higher than the downlink. In this paper, a dynamic bandwidth allocation scheme is also designed to avoid that. At last, simulation results highlight the spectral efficiency improvement of the proposed on-board processing ACM scheme over the existing ACM scheme.

关键词： ACM DVB-S2/DVBRCS2 GEO regenerative satellite asymmetric channel fading on-board processing adaptive coding Satellite systems spectral efficiency Downlink Regenerative satellite uplink Satellite communication systems transfer mode satellites

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