一种软硬件结合的POCSAG码解码装置研制

针对POCSAG码的编码格式,研制了一种基于单片机的接收解码装置。介绍了该装置的硬件组成和工作原理及软件的设计思路。     

基于游程特征的线性分组码与卷积码类型识

针对线性分组码与卷积码的类型识别问题,本文提出了一种基于游程特征的信道编码类型识别方法。论文从理论上分析了两种编码游程特性存在的差异,即卷积码的游程具有较好的随机性而线性码游程的随机性较差,并且线性码在信息位长度附近的游程数会发生一定的畸变。通过提取编码的游程特征,算法实现了对这两种编码类型的识别。仿真结果验证了所提识别方法的有效性和鲁棒性,表明算法具有一定的工程应用前景。     

无线寻呼信息的计算机实时处理

在分析国际无线寻呼标准编码POCSAG(Post Office Code Standardization Adviso-ry Group)码的基础上,利用现有BB机的射频接收部分,以MCS-51单片微处理器为主体,设计了一个最小系统,实现对无线寻呼信号的射频解调、同步接收、通信纠错等处理,然后通过RS-232C标准串行接口传送到IBM-PC微型计算机中,进行信息译码,并在微机监视器上实时显示.     

Micro QR和QR码结构附加模式的研究与实现

Micro QR是ISO/IEC 18004:2006标准中提出的一个新特性,结构附加模式是QR码的一种容量扩展特性。经过对现有二维码开源软件的调研,发现目前没有对这两种特性提供支持的。为提供对这两种编码功能的支持,对现有的ISO标准化文档和开源二维码软件代码进行了分析。发现开源软件Zxing的代码有逻辑清晰、方便扩展和良好编码风格等特性。因此,通过对比和研究Micro QR和结构附加模式编码步骤与Zxing的QR码编码实现方法,对Zxing代码进行了修改和扩展,完成了这两种特性的代码实现。使其完全支持Micro QR和结构附加模式的编码,并通过实例程序验证了生成的二维码图像的正确性。     

Micro QR和QR码结构附加模式的研究与实现

MicroQR是ISO／IEC18004：2006标准中提出的一个新特性,结构附加模式是QR码的一种容量扩展特性。经过对现有二维码开源软件的调研,发现目前没有对这两种特性提供支持的。为提供对这两种编码功能的支持,对现有的ISO标准化文档和开源二维码软件代码进行了分析。发现开源软件Zxing的代码有逻辑清晰、方便扩展和良好编码风格等特性。因此,通过对比和研究MicroQR和结构附加模式编码步骤与Zxing的QR码编码实现方法,对Zxing代码进行了修改和扩展,完成了这两种特性的代码实现。使其完全支持MicroQR和结构附加模式的编码,并通过实例程序验证了生成的二维码图像的正确性。     

利用89C2051实现POCSAG编码的方法

POCSAG(Post Office Code Standardization Advi-sory Group)码已广泛用于无线寻呼系统,目前,该系统已遍及全国城乡。其中,寻呼机作为一种接收机,具有灵敏度高、抗干扰能力强、接收误码率低、技术成熟、成本低等优点,因此对其进行二次开发,将其用作无线遥控接收机,可以有效地降低研制成本,加快研制进度,提高产品的性价比。为此,需对POCSAG码的编码格式、校验方法、编程实现等进行研究。     

单向隔离系统中的丢包恢复技术研究与实现

在高安全域的网络中需要用单向隔离系统进行数据传输,该类系统具有无反馈的特性。本文提出FEC丢包恢复技术来解决单向隔离系统可靠传输的问题。其分为两级:第一级是基于RS码通过在信息包后添加冗余数据包;第二级是在包组间进行交织编码。测试结果证明方案能够很好地恢复出单向数据传输中丢失的数据包。     

基于无线寻呼的信息助理机研究与开发

介绍了利用通用单片机采集无线寻呼接收器输出的码流,采用软件方法对POCSAG码进行解码,以及开发低价格、多功能无线信息助理机的方法。     

汉字发生系统设计与汉字图象数据压缩

本文讨论了完备的汉字发生系统设计的主要问题,给出了一个实用的压缩汉字图象数据的方法——笔元法,着重讨论了印刷体汉字图象结构信息的编码压缩,并提出了一个理论模型:汉字集的几何结构用一个特殊的有向图表示,汉字集结构信息的编码问题成为有向图的编码问题。定义了图的同构等价性及在一定编码映射下有向边的边权,图的总边权是汉字集结构码的总长度。编码的优化是通过对有向图进行一系列同构等价变挟产生最小图,并对最小图的边和节点作统计分析而得出。     

改进的CABAC与SPIHT编码算法研究

为提高图像压缩效率,提出了分段自适应二进制算术编码CABAC与SPIHT算法相结合的混合编码算法,并从理论和仿真实验两个方面证明了该算法的有效性。根据SPIHT算法产生码流概率的特点及二进制熵编码的特性将SPIHT算法产生的二进制码流分为符号和数据两段,并按照SPIHT编码阈值对数据码流再次分段,采用优化的CABAC对各二进制码流段分别编码,在不增加计算量的情况下能够得到更好的图像压缩效果。     

The classical-quantum multiple access channel with conferencing encoders and with common messages

We prove coding theorems for two scenarios of cooperating encoders for the multiple access channel with two classical inputs and one quantum output. In the first scenario (ccq-MAC with common messages), the two senders each have their private messages, but would also like to transmit common messages. In the second scenario (ccq-MAC with conferencing encoders), each sender has its own set of messages, but they are allowed to use a limited amount of noiseless classical communication among each other prior to encoding their messages. This conferencing protocol may depend on each individual message they intend to send. The two scenarios are related to each other not only in spirit—the existence of near-optimal codes for the ccq-MAC with common messages is used for proving the existence of near-optimal codes for the ccq-MAC with conferencing encoders.     

The Data Broadcast Problem with Non-Uniform Transmission Times

The Data Broadcast Problem consists of finding an infinite schedule to broadcast a given set of messages so as to minimize a linear combination of the average service time to clients requesting messages, and of the cost of the broadcast. This problem also models the Maintenance Scheduling Problem and the Multi-Item Replenishment Problem. Previous work concentrated on a discrete-time restriction where all messages have transmission time equal to 1. Here, we study a generalization of the model to a setting of continuous time and messages of non-uniform transmission times. We prove that the Data Broadcast Problem is strongly NP -hard, even if the broadcast costs are all zero, and give 3-approximation algorithms.     

Temporally enhanced erasure codes for reliable communication protocols

In forward error correction (FEC), redundant encoded packets are transmitted to and decoded by receiver(s) so that up to a certain number of lost packets can be recovered by using those redundant packets. The data stream is divided into blocks, and encoded packets are generated within each block. Hence, the encoding and decoding are performed on block-by-block basis.In this paper, a new mechanism named as temporally enhanced FEC (TEFEC) is proposed as an enhancement to the existing block-based FEC codes such as erasure codes. In TEFEC, the scopes of encoding and decoding are expanded beyond block boundaries, and they may overlap with scopes of neighboring blocks. To show its feasibility, TEFEC is applied to erasure codes to enhance their error correction capability, and new codes named as temporally enhanced erasure codes (TEEC) are developed and presented in this paper. In addition, to show its advantages, a reliable protocol was designed and simulated by combining both automatic repeat request and TEEC techniques. In terms of average packet retransmission rates and end-to-end delays for packet delivery, it is shown that the protocol employing TEEC outperforms block-by-block based protocols in most of the cases.     

旅行商问题的一种插入交叉算子

求解TSP问题是遗传算法应用的一个重要领域,其本质是TSP问题中巡回路径编码串的组合最优化问题。对于符号编码方式的遗传算法,通常需要设计特定的交叉算子以提高算法的运行效率和性能。该文针对自然数编码的方式,提出了一种较适合于大规模TSP问题求解的遗传交叉算子:插入交叉(InsertCrossover,简称IX)算子。该算子以优良的交叉策略,保证了算法的快速收敛和全局寻优。仿真实验结果证明,IX算子对于大规模TSP问题具有比较好的性能。     

EF-MPR,a new energy eFficient multi-point relay selection algorithm for MANET

MultiPoint Relay (MPR) selection algorithm is a flooding technique for propagating a broadcast message inside an ad-hoc network which reduces the number of unnecessary broadcast messages in order to save more energy in the network, minimize the number of packet collisions, and speed up the propagation time. In this paper, we demonstrate that MPR selection is an application of Set Covering Problem (SCP). A few optimization methods are developed in this work to find the optimum solution including Simulated Annealing (SA), Tabu Search (TS), Genetic Algorithm (GA), and a new greedy algorithm. Extensive simulations are set up to evaluate the developed methods. The new algorithm is named Energy eFficient MPR or EF-MPR in short. The simulation results show that EF-MPR can reduce the number of MPR nodes up to 19%. Moreover, EF-MPR algorithm reduces the power-consumption of network up to 12% and speed up the propagation time by 9%.     

The Data Broadcast Problem with Non-Uniform Transmission Times

Abstract. The Data Broadcast Problem consists of finding an infinite schedule to broadcast a given set of messages so as to minimize a linear combination of the average service time to clients requesting messages, and of the cost of the broadcast. This problem also models the Maintenance Scheduling Problem and the Multi-Item Replenishment Problem. Previous work concentrated on a discrete-time restriction where all messages have transmission time equal to 1. Here, we study a generalization of the model to a setting of continuous time and messages of non-uniform transmission times. We prove that the Data Broadcast Problem is strongly NP -hard, even if the broadcast costs are all zero, and give 3 -approximation algorithms.     

Quantum error correction via convex optimization

We show that the problem of designing a quantum information processing error correcting procedure can be cast as a bi-convex optimization problem, iterating between encoding and recovery, each being a semidefinite program. For a given encoding operator the problem is convex in the recovery operator. For a given method of recovery, the problem is convex in the encoding scheme. This allows us to derive new codes that are locally optimal. We present examples of such codes that can handle errors which are too strong for codes derived by analogy to classical error correction techniques.     

Fast and low-complexity encoding of Raptor codes based on operation lists for known source block lengths

Raptor codes can provide good error correction capability and efficient encoding and decoding rate. Its fountain code property is effective in avoiding packet retransmission for both unicast and multicast service delivery. Hence, there are many mobile, vehicular and broadband applications adopting it such as mobile multimedia broadcasting, multimedia communications for high-speed rails and broadband IPTV systems. In this paper, we present an efficient systematic Raptor codes encoder based on operation lists for known source block lengths. For a Raptor codes application that can frequently use one or several fixed source block lengths (i.e., the number of source symbols in a source block), we could produce the corresponding operation lists in advance and use them to generate the encoding symbols more efficiently. We first introduce the basic architecture of the proposed Raptor encoder, and then describe the details about how to generate operation lists and Raptor intermediate symbols. The simulation results show that our encoder is at least two times faster than the conventional Raptor codes encoder which is adopted by 3GPP and DVB-H. Besides, the reduction on CPU utilization for a real Raptor-based streaming server is described, which is from 11.59 % to 53.41 %, depending on the employed source block length and symbol size.     

Data hiding based on overlapped pixels using hamming code

Most data hiding schemes change the least significant bits to conceal messages in the cover images. Matrix encoding scheme is a well known scheme in this field. The matrix encoding proposed by Crandall can be used in steganographic data hiding methods. Hamming codes are kinds of cover codes. “Hamming + 1” proposed by Zhang et al. is an improved version of matrix encoding steganography. The embedding efficiency of “Hamming + 1” is very high for data hiding, but the embedding rate is low. Our proposed “Hamming + 3” scheme has a slightly reduced embedding efficiency, but improve the embedding rate and image quality. “Hamming + 3” is applied to overlapped blocks, which are composed of 2^k+3 pixels, where k=3. We therefore propose verifying the embedding rate during the embedding and extracting phases. Experimental results show that the reconstructed secret messages are the same as the original secret message, and the proposed scheme exhibits a good embedding rate compared to those of previous schemes.