Binary communication over the Gaussian channel using feedback with a peak energy constraint

We consider binary communication over the additive white Gaussian noise channel with no bandwidth constraint on the channel input signals, assuming the availability of a noiseless delayless feedback link. Although the signals at timetcan depend on the noise at timestau < tand are therefore random functions, we require that the signal energy never exceed a fixed level. We show that the optimal probability of error is attainable without the use of the feedback channel by using antipodal signals.     

A coding scheme for additive noise channels with feedback--I: No bandwidth constraint

In some communication problems, it is a good assumption that the channel consists of an additive white Gaussian noise forward link and an essentially noiseless feedback link. In this paper, we study channels where no bandwidth constraint is placed on the transmitted signals. Such channels arise in space communications. It is known that the availability of the feedback link cannot increase the channel capacity of the noisy forward link, but it can considerably reduce the coding effort required to achieve a given level of performance. We present a coding scheme that exploits the feedback to achieve considerable reductions in coding and decoding complexity and delay over what would be needed for comparable performance with the best known (simplex) codes for the one-way channel. Our scheme, which was motivated by the Robbins-Monro stochastic approximation technique, can also be used over channels where the additive noise is not Gaussian but is still independent from instant to instant. An extension of the scheme for channels with limited signal bandwidth is presented in a companion paper (Part II).     

Simple coding scheme to reduce peak factor in QPSK multicarriermodulation

The authors present a simple half-rate coding scheme to limit the peak factor of QPSK multicarrier waveforms to less than one quarter that of the uncoded carrier, using Rudin-Shapiro polynomials     

Elastic bandwidth allocation scheme with softened peak interference power constraint for the dynamic cognitive radio systems

The popularity of diverse wireless communication systems has led to increased strains on the unlicensed spectrum. However, investigations have shown that vast portions of the licensed spectrum remain underutilized across frequency, space and time. To improve the utilization of the existing radio spectrum, cognitive radio (CR) allows a secondary system to access the licensed spectrum as long as the primary system’s operation is not compromised. Two main CR transmission modes, spectrum overlay and underlay have been proposed. In the spectrum overlay mode, challenges in quality-of-service (QoS) provisioning arise due to the necessity for secondary users to vacate the channels when a primary user appears. In the underlay model, interference caused to the primary system has to be carefully managed resulting in a constraint of the secondary system’s transmit power, which causes difficulty in QoS provisioning. In this paper, we propose an elastic bandwidth allocation scheme to make concurrent use of both spectrum overlay and underlay transmission modes. Different from existing hybrid transmission strategy, our scheme employ a novel softened peak interference power constraint to improve the performance of the secondary system while still granting the superior protection to the primary system transmissions. This allows the proposed scheme to achieve a superior transmission capacity in the CR network while avoiding the weaknesses of the both spectrum overlay and spectrum underlay transmission modes.     

On a hybrid beamforming/space-time coding scheme

A multiple transmit antenna system based on hybrid beamforming and space-time coding technologies is examined. The reduction factor of the required transmitted energy achievable by the use of hybrid scheme is quantified for any given outage capacity. We show that although a sole space-time coding configuration is superior asymptotically (i.e., for extremely low outage requirements), a hybrid beamforming/space-time coding configuration can be a more effective solution for modest outage requirements. It may provide a useful design guideline for wireless systems, especially for the downlink where multiple transmit antenna scheme is feasible.     

On bit-error probability of a concatenated coding scheme

This paper presents a method for evaluating the bit-error probability of a concatenated coding system for BPSK transmission over the AWGN channel. In the concatenated system, a linear binary block code is used as the inner code and is decoded with the soft-decision maximum likelihood decoding, and a maximum distance separable code (or its interleaved code) is used as the outer code and is decoded with a bounded distance decoding. The method is illustrated through a specific example in which the inner code is a binary (64.40.8) Reed-Muller subcode and the outer code is the NASA standard (255, 223, 33) Reed-Solomon code over GF(2⁸) interleaved to a depth of 5. This specific concatenated system is being considered for NASA's high-speed satellite communications. The bit-error performance is evaluated by a combination of simulation and analysis. The split weight enumerators for the maximum distance separable codes are derived and used for the analysis     

Sequential signalling under a peak power constraint

The error exponent for sequential signaling over the additive-Gaussian-white-noise channel subject to a peak power constraint is derived. This exponent is maximum under the assumption that information is transmitted in blocks.     

Low‐complexity energy efficient power allocation scheme for DAS with maximum power constraint

In this paper, a low‐complexity optimal power allocation (PA) scheme is developed to maximize energy efficiency (EE) in a distributed antenna system (DAS) under maximum power constraint and target bit error rate (BER) requirement. Composite Rayleigh fading, multiple receive antennas, and dynamic circuit power consumption are all considered in the system. Unlike conventional schemes, the presented scheme provides a closed‐form expression of PA. Firstly, the optimization problem is formulated according to the definition of EE. Using the Karush‐Kuhn‐Tucker conditions, a general form of the optimal PA, in which the number of active antennas and corresponding power allocation are required only, is then proposed. With this general form, an effective algorithm is presented to yield the closed‐form PA. The proposed scheme can be applied to the system with static circuit power consumption and/or without target BER constraint to obtain optimal PA. Simulation results corroborate the effectiveness of the developed scheme, and the scheme can achieve the same EE performance as the existing optimal schemes with lower complexity. Moreover, the distributed antenna system with multiple receive antennas has higher EE than that with single receive antenna.     

Strong universal source coding subject to a rate-distortion constraint

The following problem in universal source coding is explored. Some members of a class of sources have various constraints on the maximum rate at which they may be encoded, and thc remainder have various constraints on the maximum distortion that may result from encoding. It is desired to find a universal code that will adapt its performance so that whatever source in the class is encoded, the resulting performance meets the constraint and is optimal in the rate-distortion function sense for that particular source. It is shown that such codes exist when the class is totally bounded and the constraints are uniformly continuous in an appropriate sense. A key result shows that the value of any uniformly continuous function on a totally bounded class can be uniformly well estimated from observations of the output of any source in     

On the feedback error compensation for adaptive modulation and coding scheme

In this paper, we consider the effect of feedback error on the performance of the joint adaptive modulation and diversity combining (AMDC) scheme which was previously studied with an assumption of perfect feedback channels. We quantify the performance of two joint AMDC schemes in the presence of feedback error, in terms of the average spectral efficiency, the average number of combined paths, and the average bit error rate. The benefit of feedback error compensation with adaptive combining is also quantified. Selected numerical examples are presented and discussed to illustrate the effectiveness of the proposed feedback error compensation strategy with adaptive combining. Copyright © 2011 John Wiley & Sons, Ltd.     

Regularized subband coding scheme

Two enhanced subband coding schemes using a regularized image restoration technique are proposed: the first controls the global regularity of the decompressed image; the second extends the first approach at each decomposition level. The quantization scheme incorporates scalar quantization (SQ) and pyramidal lattice vector quantization (VQ) with both optimal bit and quantizer allocation. Experimental results show that both the block effect due to VQ and the quantization noise are significantly reduced.     

Variable-rate universal block source coding subject to a fidelity constraint

Variable-rate universal source codes are data compression schemes that are optimum for the coding of a collection of sources (e.g., a source with unknown parameters) subject to a fixed average distortion constraint. Existence of variable-rate universal source codes is demonstrated for very general classes of sources and distortion measures.     

Serial concatenated coding scheme with minimum shift keying

A novel serially concatenated coding scheme for use with minimum shift keying (MSK) is proposed. The novelty is to use a mixture of recursive and non-recursive realisations for the MSK modulator. It is shown that this improves the performance of iterative demodulation and decoding of convolutionally encoded MSK signals with a slight decrease in the decoder complexity     

新型高效编码调制方式

在无线局域网中有很多调制方式,每个方式有它自己的特点。补码键控被采用可支持5.5Mbps,11Mbps,22Mbps,33Mbps的数据速率。超过了以前无线局域网标准2Mbps的速率。但是CCK在室内多径环境下性能相当不好。文中一个新的调制方案是把网格编码和CCK调制结合起来提出来的。通过仿真,这种方式在中到大的时延扩展信道环境下表现比较好的误码性能。     

单天线功率受限的自适应调制V-BLAST系统

提出了一种在单天线峰值瞬时功率和总平均功率都受限条件下的改进注水法和离散调制的比特、功率分配方法,并应用于自适应调制V-BLAST系统.如果由注水法得到的分配结果中某发射天线的瞬时功率高于峰值功率限制,就修正该天线的分配比特数和功率使之满足限制要求,剩余的功率再由注水法分配到其他天线上.仿真结果表明,提出的算法很好地满足了目标要求,而且单天线功率受限使比特率有所下降.     

级联信道编码的多幅值差分空时分组码方案及性能

通过引入多电平振幅调制和变换矩阵方法,提出了一种基于多幅值调制的差分正交空时分组码方案。该方案可克服通常基于PSK调制的单幅值差分空时码(DSTC,differential space-time coding)在高频带利用率下由于星座符号间的最小距离减小所带来的性能下降,而且可用于编码矩阵是非方阵情况,避免了已有方案仅适合于方阵码矩阵。与已有单幅值DSTC相比,所提方案有着高的频谱效率和编码增益,且可实现线性译码复杂度和高的码率。此外,还给出了所提方案级联信道编码时的性能。仿真结果表明所提方案与已有单幅值DSTC方案相比,有着较低的误比特率,而且信道编码后的所提多幅值DSTC也好于相应的单幅值DSTC。     

Robust differential chain coding scheme

In differential chain coding (DCC), the bandwidth efficient relative vector is sensitive to channel errors, resulting in error propagation and corruption of the decoding process. A robust differential chain coding scheme is presented for stopping error propagation in the relative vector without increasing its bandwidth or using an additional forward error correction code. In this scheme, the relative vector is combined with the previous absolute vector to form a new error-resistant channel codeword. Experiments showed that, compared to DCC, the new scheme notably improves subjective quality when subject to transmission errors     

基于时空多样性编码的低轮值无线传感器网络可靠传输算法

提出了适用于低轮值无线传感器网络的可靠传输算法,主要特点是发掘并利用低轮值无线传感器网络特有的时空相关性,结合编码机制以获得较高的能量效率和较低的传输时延。针对编码块在多条路径上的最优分配问题进行了建模。由于求解最优策略是NP难题,给出了近似算法,并通过仿真分析了不同参数对近似算法的影响。仿真结果表明,基于时空多样性编码的分配算法能够在较低的能量开销条件下,实现低时延的可靠传输。     

VIDEO CODING SCHEME FOR ATM NETWORKS

A new variable bit rate layered coding scheme based on subband coding is given in this paper. It can make full use of the merits of ATM transmission, as well as compensation for the quality degradation caused by cell loss, which is an inherent problem of ATM networks, and thus a stable, high quality video transmission is achieved. This paper presents the coding scheme, cell construction and simulation results.     

A general coding scheme for the two-way channel

A general coding scheme for the nonrestricted memoryless discrete two-way channel is presented based on the introduction of auxiliary random variables forming a stationary Markov process. The coding scheme yields an achievable rate region which exceeds the inner bound of Shannon in the general case. A finite cardinality bound for the auxiliary random variables is given, showing that the region is computable. Finally, the capacity region for the memoryless Gaussian two-way channel is established.