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Enhancing closed-loop wireless systems through efficient feedback reconstruction

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2007年第5期56卷 2941-2953页

作者： Heidari, Abdorreza Lahouti, Farshad Khandani, Amir K. Univ Waterloo Dept Elect & Comp Engn Coding & Signal Transmiss Lab Waterloo ON N2L 3G1 Canada Univ Tehran Coll Engn Sch Elect & Comp Engn Tehran 14174 Iran

The closed-loop transmit diversity technique is used to improve the performance of the downlink channel in multiple-input multiple-output (MIMO) communication systems. The wideband code-division multiple-access standard endorsed by the Third Generation Partnership Project (3GPP) adopts a downlink closed-loop scheme based on partial channel state information (CSI) known as mode 1. The information is fed back from the mobile unit to the base station through a low-rate uncoded feedback bit stream. In this paper, several reconstruction techniques are introduced to improve the performance of mode 1 of 3GPP in the presence of feedback error by taking advantage of the redundancy available in the bit stream of the CSI. We propose a number of algorithms for the reconstruction of beamforming weights at the base station with the constraint of a constant transmit power. The performance is examined within a simulated 3GPP framework. It is demonstrated that the proposed algorithms have substantial gain over the conventional method for low, moderate, and high mobile speeds. It is also shown that the proposed algorithms can substitute the antenna weight verification process done at the mobile unit in many cases. The proposed approach is applicable to other feedback schemes as well.

关键词： antenna weight verification (AV) channel feedback channel state information (CSI) closed-loop transmit diversity downlink communication frequency-division-duplex (FDD) wideband code-division multiple access (WCDMA) joint source-channel coding mode 1 of the Third Generation Partnership Project (3GPP)

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Unequal Power Allocation for JPEG Transmission Over MIMO Systems

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2010年第2期19卷 410-421页

作者： Sabir, Muhammad Farooq Bovik, Alan Conrad Heath, Robert W., Jr. VuCOMP Inc Richardson TX 75080 USA Univ Texas Austin Dept Elect & Comp Engn Lab Image & Video Engn Austin TX 78712 USA Univ Texas Austin Dept Elect & Comp Engn Austin TX 78712 USA

With the introduction of multiple transmit and receive antennas in next generation wireless systems, real-time image and video communication are expected to become quite common, since very high data rates will become available along with improved data reliability. New joint transmission and coding schemes that explore advantages of multiple antenna systems matched with source statistics are expected to be developed. Based on this idea, we present an unequal power allocation scheme for transmission of JPEG compressed images over multiple-input multiple-output systems employing spatial multiplexing. The JPEG-compressed image is divided into different quality layers, and different layers are transmitted simultaneously from different transmit antennas using unequal transmit power, with a constraint on the total transmit power during any symbol period. Results show that our unequal power allocation scheme provides significant image quality improvement as compared to different equal power allocations schemes, with the peak-signal-to-noise-ratio gain as high as 14 dB at low signal-to-noise-ratios.

关键词： Distortion model joint source-channel coding JPEG multiple-input multiple-output systems unequal error protection unequal power allocation

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Benefits of Cache Assignment on Degraded Broadcast channels

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IEEE TRANSACTIONS ON INFORMATION THEORY 2019年第11期65卷 6999-7019页

作者： Bidokhti, Shirin Saeedi Wigger, Michele Yener, Aylin Univ Penn Dept Elect & Syst Engn Philadelphia PA 19104 USA IP Paris Telecom Paris LTCI F-75013 Paris France Penn State Univ Dept Elect Engn Sch Elect Engn & Comp Sci State Coll PA 16802 USA

Degraded K-user broadcast channels (BCs) are studied when the receivers are facilitated with cache memories. Lower and upper bounds are derived on the capacity-memory tradeoff, i.e., on the largest rate of reliable communication over the BC as a function of the receivers' cache sizes, and the bounds are shown to match for interesting special cases. The lower bounds are achieved by two new coding schemes that benefit from 'nonuniform cache assignments'. Lower and upper bounds are also established on the global capacity-memory tradeoff, i.e., on the largest capacity-memory tradeoff that can be attained by optimizing the receivers' cache sizes subject to a total cache memory budget. The bounds coincide when the total cache memory budget is sufficiently small or sufficiently large, where the thresholds depend on the BC statistics. For small cache memories, it is optimal to assign all the cache memory to the weakest receiver. In this regime, the global capacity-memory tradeoff grows by the total cache memory budget divided by the number of files in the system. In other words, a 'perfect global caching gain' is achievable in this regime and the performance corresponds to a system where all the cache contents in the network are available to all receivers. For large cache memories, it is optimal to assign a positive cache memory to every receiver, such that the weaker receivers are assigned larger cache memories compared to the stronger receivers. In this regime, the growth rate of the global capacity-memory tradeoff is further divided by the number of users, which corresponds to a local caching gain. It is observed numerically that a uniform assignment of the total cache memory is suboptimal in all regimes, unless the BC is completely symmetric. For erasure BCs, this claim is proved analytically in the regime of small cache sizes.

关键词： Broadcast channel (BC) caching capacity-memory tradeoff Gaussian channels joint source-channel coding

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Optimal resource allocation for Medium Grain Scalable video transmission over MIMO channels

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JOURNAL OF VISUAL COMMUNICATION AND IMAGE REPRESENTATION 2013年第3期24卷 373-387页

作者： Hamidouche, Wassim Olivier, Christian Pousset, Yannis Perrine, Clency Univ Poitiers CNRS Dept Signal Image & Commun XLIM LabUMR 7252 Poitiers France

In this paper we investigate an optimal solution for adaptive H.264/SVC video transmission over Multiple-Input Multiple-Output (MIMO) channels. We first write the end-to-end distortion of the H.264/SVC video transmission over a diagonal MIMO channel. The total distortion is expressed following three physical layer parameters: power allocation, modulation spectral efficiency and Error Code Correction (ECC) code rate. Minimizing the total distortion is considered as an optimization problem containing both discrete and continuous variables. We use the Lagrangian method associated with Karush-Kuhn and Tucker conditions to find out the optimal continuous physical layer parameters. Concerting the discrete modulation spectral efficiency and ECC code rate, we exploit information of the MIMO system to remove all suboptimal configurations. Therefore, the optimal power allocation is computed only for a reduced number of discrete configurations. The performance of the proposed solution is evaluated over both statistical and realistic MIMO channels. Results show that the proposed solution performs an optimal resource allocation to achieve the best QoS regardless the channel conditions. (c) 2013 Elsevier Inc. All rights reserved.

关键词： joint source-channel coding Wireless video streaming Optimal resource allocation H.264/SVC Rate-distortion optimization MIMO channels IEEE802.11n QoS

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Real-time error protection of embedded codes for packet erasure and fading channels

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2004年第8期14卷 1064-1072页

作者： Stankovic, VM Hamzaoui, R Xiong, ZX Texas A&M Univ Dept Elect Engn College Stn TX 77843 USA Univ Konstanz Dept Informat & Comp Sci D-78464 Constance Germany

Reliable real-time transmission of packetized embedded multimedia data over noisy channels requires the design of fast error control algorithms. For packet erasure channels, efficient forward error correction is obtained by using systematic Reed-Solomon (RS) codes across packets. For fading channels, state-of-the-art performance is given by a product channel code where each column code is an RS code and each row code is a concatenation of an outer cyclic redundancy check code and an inner rate-compatible punctured convolutional code. For each of these two systems, we propose a low-memory linear-time iterative improvement algorithm to compute an error protection solution. Experimental results for the two-dimensional and three-dimensional set partitioning in hierarchical trees coders showed that our algorithms provide close to optimal average peak signal-to-noise ratio performance, and that their running time is significantly lower than that of all previously proposed solutions.

关键词： embedded codes image compression joint source-channel coding unequal error protection

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Interactive Computation of Type-Threshold Functions in Collocated Gaussian Networks

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IEEE TRANSACTIONS ON INFORMATION THEORY 2015年第9期61卷 4765-4775页

作者： Wang, Chien-Yi Jeon, Sang-Woon Gastpar, Michael Ecole Polytech Fed Lausanne Sch Comp & Commun Sci CH-1015 Lausanne Switzerland Andong Natl Univ Dept Informat & Commun Engn Andong 760749 South Korea

In wireless sensor networks, various applications involve learning one or multiple functions of the measurements observed by sensors, rather than the measurements themselves. This paper focuses on the class of type-threshold functions, e.g., the maximum and the indicator functions. A simple network model capturing both the broadcast and superposition properties of wireless channels is considered: the collocated Gaussian network. A general multiround coding scheme exploiting superposition and interaction (through broadcast) is developed. Through careful scheduling of concurrent transmissions to reduce redundancy, it is shown that given any independent measurement distribution, all type-threshold functions can be computed reliably with a nonvanishing rate in the collocated Gaussian network, even if the number of sensors tends to infinity.

关键词： Gaussian networks interactive computation joint source-channel coding type-threshold functions

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Progressive video delivery over wideband wireless channels using space-time differentially coded OFDM systems

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2006年第4期5卷 303-316页

作者： Zhao, SJ Xiong, ZX Wang, XD Hua, JP Lucent Technol Bell Labs Wireless Innovat Open Labs Adv Wireless Syst Technol & Algorithms Grp Whippany NJ 07981 USA Texas A&M Univ Dept Elect & Comp Engn College Stn TX 77843 USA Columbia Univ Dept Elect Engn New York NY 10027 USA Translat Gen Res Inst Phoenix AZ 85004 USA

Progressive video delivery over wireless networks is very challenging due to the time-varying nature of wireless channels and limited power in the mobile devices. This paper proposes an end-to-end architecture for multilayer progressive video delivery over space-time differentially coded orthogonal frequency division multiplexing (STDC-OFDM) systems. An input video sequence is compressed by 3D-ESCOT into a layered bitstream. We input multiple layers of the bitstream in series to a STDC-OFDM channel. Different video source layers are protected by different error protection schemes in order to achieve unequal error protection. In progressive transmission, the reconstruction quality is important not only at the target transmission rate but also at the intermediate rates. So, the error protection strategy needs to optimize the average performance over the set of intermediate rates. We propose to use progressive joint source-channel coding to generate operational transmission distortion-rate (TD-R) functions and operational transmission distortion-power (TD-P) functions for multiple layers before forming the operational transmission distortion-power-rate (TD-PR) surfaces. Lagrange multipliers are then employed on the fly to obtain the optimal power allocation and optimal rate allocation among multiple layers, subject to constraints on the total transmission rate and the total power level. Progressive joint source-channel coding offers the scalability feature to handle bandwidth variations and changes in channel conditions. By extending the rate-distortion function in source coding to the TD-PR surface in joint source-channel coding, our work can use the "equal slope" argument to effectively solve the transmission rate allocation problem as well as the transmission power allocation problem for multilayer video transmission. Experiments show that our scheme achieves significant improvement over a nonoptimal system with the same total power level and total transmission rate

关键词： joint source-channel coding scalable video coding progressive transmission STDC-OFDM systems rate allocation power allocation

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Computation over multiple-access channels

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IEEE TRANSACTIONS ON INFORMATION THEORY 2007年第10期53卷 3498-3516页

作者： Nazer, Bobak Gastpar, Michael Univ Calif Berkeley Dept Elect Engn & Comp Sci Berkeley CA 94720 USA

The problem of reliably reconstructing a function of sources over a multiple-access channel (MAC) is considered. It is shown that there is no source-channel separation theorem even when the individual sources are independent. joint source-channel strategies are developed that are optimal when the structure of the channel probability transition matrix and the function are appropriately matched. Even when the channel and function are mismatched, these computation codes -often outperform separation-based strategies. Achievable distortions are given for the distributed refinement of the sum of Gaussian sources over a Gaussian multiple-access channel with a joint source-channel lattice code. Finally, computation codes are used to determine the multicast capacity of finite-field multiple-access networks, thus linking them to network coding.

关键词： distributed computation joint source-channel coding lattice codes linear codes multiple-access channel (MAC) network coding separation theorem

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joint turbo decoding and estimation of hidden Markov sources

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2001年第9期19卷 1671-1679页

作者： Garcia-Frias, J Villasenor, JD Univ Delaware Dept Elect & Comp Engn Newark DE 19716 USA Univ Calif Los Angeles Dept Elect Engn Los Angeles CA 90024 USA

We describe a joint source-channel scheme for modifying a turbo decoder in order to exploit the statistical characteristics of hidden Markov sources. The basic idea is to treat the trellis describing the hidden Markov source as another constituent decoder which exchanges information with the other constituent decoder blocks. The source block uses as extrinsic information the probability of the input bits that is provided by the constituent decoder blocks. On the other hand, it produces a new estimation of such a probability which will be used as extrinsic information by the constituent turbo decoders. The proposed joint source-channel decoding technique leads to significantly improved performance relative to systems in which source statistics are not exploited and avoids the need to perform any explicit source coding prior to transmission. Lack of a priori knowledge of the source parameters does not degrade the performance of the system, since these parameters can be jointly estimated with turbo decoding.

关键词： Baum-Welch algorithm hidden Markov sources iterative decoding joint source-channel coding turbo codes

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Error-resilient surveillance video transmission based on a practical joint source-channel distortion computing model

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JOURNAL OF SUPERCOMPUTING 2017年第3期73卷 1017-1043页

作者： Jung, Tae-jun Jeong, Yo-Won Lee, Hong-rae Seo, Kwang-deok Yonsei Univ Div Comp & Telecommun Engn Wonju Gangwon South Korea Samsung Elect Corp Digital Media & Commun R&D Ctr Suwon Gyeonggi South Korea

In recent years, IP (Internet Protocol)-based video surveillance has widely been useful for post-event analysis and assisting the work of privacy protection and public safety. To support high-quality IP video surveillance, error-resilience techniques are important for surveillance system design, because video has more stringent requirements than general video transmission for packet loss, latency, and jitter. The optimal FEC (forward error correction) code rate decision is a crucial procedure to determine the optimal source and channel coding rates to minimize the overall picture distortion when transporting video packets over packet loss channels. The conventional FEC code rate decision schemes using an analytical source-coding distortion model and a channel-induced distortion model are usually complex and typically employ the process of model parameter training, which involves potentially high computational complexity and implementation cost. To avoid the complex modeling procedure, we propose a simple but accurate joint source-channel distortion model to estimate the channel-loss threshold set for optimal FEC code rate decision. Since the proposed model is expressed as a simple closed form and has a small number of scene-dependent model parameters, a video sender of the surveillance system using the model can be easily implemented. For training the scene-dependent model parameters in real time, we propose a practical test-run procedure. This method accelerates the test-run while maintaining its accuracy for training the scene-dependent model parameters. Using the proposed simple model and practical test-run method, the video sender can find the optimal code rate for on-the-fly joint source-channel coding whenever there is a change in the packet-loss condition in the channel. Simulations show that the proposed method can accurately estimate the channel loss threshold set, resulting in an optimal FEC code rate with low computational complexity.

关键词： FEC code rate decision Forward error correction Error-resilient surveillance video transmission joint source-channel coding

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