Sequence-switch coding for low-power data transmission

Reducing the power dissipated by buses becomes one of the most important elements in low-power VLSI design. A new coding scheme called sequence-switch coding (SSC) is proposed in this paper. It is a general-purpose coding scheme that employs the sequence of data in reducing the number of transitions on buses. A simple switching algorithm is presented to show the feasibility of SSC. According to simulations, this algorithm reduces around 10% of bus transitions in the transmission of benchmark files. SSC can be used for burst data transfer in any application. In particular, it is suitable for internet and multimedia applications that have stream-type data transfer pattern.     

Safety and reliability of synchronizable digital coding in railwaytrack-circuits

The incorporation of digital error-control coding into railway track circuits represents a new approach for track-train data transmission for automatic train control. Methods based on error probability analysis are presented for assessing the safety and reliability of synchronizable error control coding in this application. The results for a sample coding scheme have been verified by experimentation using a calibrated source injecting audio-frequency Gaussian noise into a practical track circuit. Safety and reliability must be traded off, although the safety can be increased by incorporating dictionary checking in the code-receiver algorithm and the reliability can be enhanced by allowing single synchronization error correction. The technique demonstrates the possibility of designing a track-circuit data transmission system to given target safety and reliability levels of the same order of magnitude as the known failure rates of existing equipment     

Optimal data transmission filters

In the letter new closed-form formulas (in terms of the poles) for a class of optimal data transmission filters are derived. These formulas always put the main sample point at the peak value of the impulse response.     

高铁毫米波最优自适应波束成形与联合传输

高铁车地移动通信系统的吞吐量不仅受到频谱的限制,而且受到高移动性的限制,已成为制约智能高铁发展的重要瓶颈。一种提高系统吞吐量的有效方法是使用拥有较宽连续频谱的毫米波频段以及使用大规模多输入多输出(MIMO)和多波束成形技术。然而,使用固定波束宽度的多波束流在列车高速行驶过程中会产生严重的波束间干扰,因此,论文提出了基于最优波束宽度的自适应波束成形和联合传输方案。当列车距离基站较近时,激活全部波束,实现波束的空间复用,提高系统容量和传输可靠性。当列车距离基站较远时,为了避免波束间的严重干扰,用更多的天线阵元形成较少的波束,获得更大的波束增益,并与相邻基站进行波束联合传输,提升系统的吞吐量。仿真结果表明,与现有波束成形及传统自适应选择方案相比,所提方案吞吐量在小区边缘附近可以提升超过150%。     

基于空时编码的高效星地数据传输技术

为提升星地数据传输效率,多采用时间域变速率传输模式,但改善程度有限。文中从空间域角度着手,提出基于空时编码的高效星地数据传输技术,通过空时预编码将多个混叠的数据流分离开来,形成多个编码通道同时传输多路并发数据,并且能够在空间域上收集散射、反射路径功率,从而充分利用有限的链路功率。分析与仿真结果显示,采用星上2天线对2个用户的传输模式,相比传统点对点的传输模式其频谱效率可提升0.5～1 b?s~(-1)?Hz~(-1)。     

基于网络编码的配电网络下行数据路由算法

文中讨论了利用网络编码技术和使用冗余链路来提高配电网络下行监控网络端对端吞吐量的算法,并通过仿真结果说明了建立多条链路的方法能以较小的网络延迟代价,显著地增强监控网络下行链路的吞吐量,可以提高网络链路的使用。     

Intraframe coding for picture transmission

A great variety of intraframe coding techniques have been proposed and demonstrated in recent years. Most of them exploit the properties of both the image and the human viewer. These properties are discussed briefly so as to provide a framework for describing the various coding techniques. The development of intraframe coders has been an evolutionary process. Techniques such as delta modulation (DM) and differential pulse code modulation (DPCM) which were proposed in the early 1950's are still being actively studied and improved today. A survey of this early work is given as a preliminary to more detailed discussion of the work from 1967 to the present. Three main approaches are evident in these studies. First, by making linearizing assumptions, frequency domain analysis can be applied to the problem of minimizing the visibility of granular coding noise. Second, in order to exploit the nonlinear properties of the human visual system, a time domain approach to the development of coding algorithms is found most useful. Third, by exploiting only the statistics of the source, efficient reversible encoding operations can be developed. These three approaches are dealt with in some detail. Possible avenues for further research are pointed out.     

Multilevel coding for multiple-antenna transmission

The application of powerful coding for transmission over multiple-input/multiple-output channels is discussed. The authors emphasize that as an immediate consequence of the mutual information chain rule, multilevel coding (MLC) constitutes the optimum coded modulation scheme. On the other hand, simple bit-interleaved coded modulation (BICM) is only a convenient alternative for the case of two transmit and one receive antennas when combined with orthogonal space-time block codes. Starting from MLC, the authors further propose a hybrid coded modulation scheme, which favorably combines the advantages of MLC and BICM.     

Correlative level coding for binary-data transmission

A new approach to binary-data transmission, termed correlative level coding, is presented, along with practical aspects based on research conducted during the past few years. Following a review of basic data-transmission concepts and definitions, the author discusses the general form of the level-coded correlative techniques, as well as the specific codes with and without carrier modulation. In the error-detection process, it has been found that with this type of system it is unnecessary to introduce redundant digits into the original data stream.     

Optimal bit allocation for FGS coding

A new bit allocation scheme for fine-granular-scalability (FGS) video coding is proposed. Differing from traditional bit allocation schemes, the focus is on understanding the relationship between rate-distortion analysis and nonzero binary-scaled coefficients (NZBC) in the bitplane coding. An optimal strategy for NZBC coding is then derived and experimental results are given for a comparison of the new scheme with uniform bit allocation.     

Practical coding for QAM transmission of HDTV

It is demonstrated how modulation schemes based on QPSK can be directly incorporated into QAM-based systems. It is argued that this leads directly to an easily implementable structure that is both efficient in bandwidth and data reliability. It is contended that the correct solution to the concatenated coding problem for HDTV transmission is to simply extend the modulation codes developed for QPSK-to-QAM modulation. In nonconcatenated situations, a trellis code based on a binary code at rate 2/3 is usually best. However, this is not the case for higher error rates at the output of the trellis decoder (e.g., when a symbol error correcting decoder follows as a concatenated code). The reason for this follows from an analysis of the effect of the number of nearest neighbors on the error rate. A four-way partition of QAM is a natural extension of QPSK modulation; it is a simple matter to incorporate any good QPSK code into a trellis coding scheme for QAM modulation. A concatenated coding scheme based on QPSK trellis codes and symbol error correcting coding is proposed. An example is presented to show the advantages of this approach     

利用空时分组编码技术提高数据传输速率的研究

未来的通信对移动通信业务的要求越来越高，随着从单纯语音业务到多媒体业务的转变，通信中数据传输速率成为抑制日后发展的因素之一。因此人们努力研究各种高效的编码、调制以及传输的技术，用以提高数据的传输速率。空时编码是近年提出的重要技术之一，这种技术已经在第三代移动通信(3G)方案中广泛应用。本文在介绍简单的空时分组编码原理的基础上，着重研究了对共道信号产生的干扰进行抵消抑制的技术。采用具有干扰抵消技术的空时分组编码系统进行并行数据传输可以充分利用干扰信号之间的相关性进行有效的抵消处理，在原有的信道上能够极大的提高数据的传输速率。文中提出了一种利用多种调制方式抗干扰性能的不同，对共道信号进行分步解码来削弱共道干扰的影响的空时分组编码并行传输策略。这种方法能够进一步提高信号传输的性能，为提高通信系统的数据传输速率做出了保证。     

Arithmetic coding for data compression

Arithmetic coding provides an effective mechanism for removing redundancy in the encoding of data. We show how arithmetic coding works and describe an efficient implementation that uses table lookup as a first alternative to arithmetic operations. The reduced-precision arithmetic has a provably negligible effect on the amount of compression achieved. We can speed up the implementation further by use of parallel processing. We discuss the role of probability models and how they provide probability information to the arithmetic coder. We conclude with perspectives on the comparative advantages and disadvantages of arithmetic coding     

Performance modeling of data transmission by using random linear network coding in DTNs

In Delay Tolerant Networks (DTNs), mobile nodes exploit encounter chances to transmit data via the established opportunistic link between encounter nodes. The transmission capacity between two encounter nodes is constrained by the duration of opportunistic links. How to transmit data efficiently is one of the fundamental and most important issues in DTNs. Recently, Random Linear Network Coding (RLNC) is proposed as a promising approach to improve data transmission efficiency in DTNs. To facilitate the development of deployment of RLNC based routing protocols, it is imperative to quantify the performance gain brought by RLNC in a rigorous and systematic way. In this paper, we develop an analytical model to evaluate the data transmission performance of RLNC based epidemic routing in DTNs. In the model, we consider that multiple unicast communication sessions compete for limited \capacity. Numerical results validate the effectiveness of our analytical model and demonstrate the significant performance improvement for data transmission in DTNs brought by RLNC. Our work of this paper provides a general tool for performance evaluation and useful guidelines for designing RLNC based routing protocols in DTNs. Copyright © 2015 John Wiley & Sons, Ltd.     

High reliability of real-time visual data transmission using superposition coding with receiver diversity

Supporting visual data applications in the real-time communication systems are among the most challenging issues over the next generation wireless communication systems. This challenge is further magnified by the fact that the quality of reception is highly sensitive to transmission delay, data losses and bit error rate (BER) in such applications. In this paper, we proposed Superposition Coding with Receiver Diversity (SPC-RD) scheme, which employs unequal error protection (UEP) to improve the error performance, maximize the received signal to noise ratio (SNR) and optimize the reliability of the transmission system. In the transmitter side, the visual data is divided into a number of different priority layers based on their effects on the reception quality. These layers are modulated individually where the highest priority layer is modulated with the highest UEP level against error-prone channels, and vice versa. These modulated signals are then superimposed together and transmitted via wireless Single-Input Multiple-Output (SIMO) Rayleigh fading channel. In the receiver side, three different diversity combining approaches; selection combining (SC), equal gain combining (EGC) and maximal ratio combining (MRC) are considered. The combined signal is then passed through a multiuser demodulator so-called the ordered successive interference cancellation (O-SIC) demodulator to reconstruct and separate the data layers. This demodulation technique is evaluated and compared with the traditionally maximum likelihood joint detection (MLJD) technique. Extensive simulations have been carried out to validate the various assertions. Under the assumption of equal transmission power, the simulation results illustrate that the proposed SPC-RD scheme provides a SNR gain of 14.5 dB over the Rayleigh fading channel at the diversity order of three for the acceptable BER level of 10^?3 when BPSK scheme is exploited compared to the traditional equal error protection system. In addition, the proposed scheme with O-SIC demodulation technique achieves almost similar performance compared to MLJD technique but using less computational complexity.     

Optimal coding strategies for certain permuting channels

We give optimal coding strategies for nonprobabilistic permuting (especially, "trapdoor") channels and also for a permuting relay channel. Our results open the door to a coding theory for nonprobabilistic (or deterministic) channels with memory.     

Optimal control of data transmission in a mobile two-agent robotic system

A method for optimization of parameters of a telecommunication and information network providing data processing and transmission in a mobile two-agent robotic system is considered. The first agent receives a Poisson stream of packets (information blocks) and retransmits them to the second agent for subsequent processing. The first agent loses the input packet if its buffer is overflown; the second agent does not admit the overflow of its buffer by sending a rejection message and requesting packet retransmission. The problem of minimization of input packet loss is solved in the steady-state mode under constraints on the processing time and energy consumption by controlling the transmission rate and rejection probability. Conditions in which the values of the objective and constraint functionals form a convex set are determined. The numerical synthesis of the control is implemented on the basis of the augmented Lagrangian method.     

Optimal coding schemes for conflict-free channel access

A method is proposed for conflict-free access of a broadcast channel. The method uses a variable-length coding scheme to determine which user gains access to the channel. For an idle channel, an equation for optimal expected overhead is derived and a coding scheme that produces optimal codes is presented. Algorithms for generating optimal codes for access on a busy channel are discussed. Suboptimal schemes are found that perform in a nearly optimal fashion. The method is shown to be superior in performance to previously developed conflict-free channel access schemes     

Optimal selection of routs in data transmission networks. Energy approach

A new algorithm has been proposed for solving the problem of optimal alternative routing based on the energy approach to the network analysis with generalization of Kirchhoff’s laws. This algorithm is the fastest among a wide class of optimization methods based on finding an admissible direction of decreasing the target function. By the example of network analysis it was shown in the case of a quadrature target function this algorithm requires only one iteration for finding an optimal solution that favorably distinguishes it from the gradient projection and other possible methods. Optimization of the same network was conducted by the criterion of average delay minimum that is one of the main criteria used in optimizing networks of queues with representative time of message servicing.