光纤通信中级联码的码型

论述了光纤通信中级联码的码型选择,从净电编码增益、编码效率、相对色散代价以及实现的复杂程度等方面讨论了几种级联码,并认为RS(255,239)-BCH(2184,2040,12)级联方案在编码效率、色散代价以及实现的复杂程度方面具有较大的优越性。     

Adaptive hybrid ARQ scheme using concatenated FEC for ATM overwireless links

A new scheme for adjusting the code rates of RS (Reed-Solomon) and CPC (complementary punctured convolutional) codes to match the channel conditions is proposed for wireless asynchronous transfer mode (WATM). The main feature of this scheme is that all retransmitted sequences are self-decodable. The proposed scheme increases the error correcting capability of RS and CPC codes and uses different code rates for the header and payload of the ATM cell according to the type of data     

M2FEC: An effective FEC based multi-path transmission scheme for interactive multimedia communication

The oncoming prosperity of interactive multimedia application triggers significant challenges to current best-effort Internet due to such application’s stringent delay, loss and bandwidth requirements, and Internet’s unpredictable dynamics. Multi-path transmission and error-resilient coding are two promising approaches to alleviate these problems. This paper attempts to introduce error-resilient coding into multi-path transmission to better trade off between multi-path bandwidth resource consumption and reliable media quality. We propose a model for multi-paths interactive multimedia transmission and develop M2FEC—a FEC based transmission scheme which maximizes the overall quality at the client under various constraints based on the proposed model. Numerical simulation and PlanetLab experiments demonstrate the effectiveness and practicability of M2FEC in theory and in empiricism, respectively.     

An ARQ/FEC coding scheme for land mobile communication

This paper describes the development of a laboratory test unit that implements a new Type I/II ARQ scheme for use on a land mobile forward satellite link. Investigation of channel characteristics showed that it was possible to use convolutional coding to combat random errors, but it was also necessary to employ an ARQ scheme in order to overcome fades due to signal blockage. The hardware development used commercial 68000-based VME cards as well as special-purpose cards to perform the functions of Viterbi decoding and packet synchronization. Results are presented for the hardware operating with Gaussian noise as time limitations excluded the use of satellite fading simulation. In order to ensure a high degree of data integrity error detection was applied to the data packets such that a residual error rate of less than 10^?11 should result. This was not able to be verified due to the limited time. However, long term tests did indicate that an error rate less than 10^?8 was achieved.     

Transformation of rain attenuation statistics from fixed to mobilesatellite communication systems

We have proposed and discussed a method to transform rain attenuation probability distributions from fixed to mobile satellite communication systems. For a given outage probability, the power margin needed in the mobile system may be larger or smaller than that in the fixed system, depending on the speed of the vehicle relative to that of the rain storm. Simulations performed using experimental information on vehicle and rain storm speeds show that the probability distribution of the mobile system can be obtained from that of the fixed system, by multiplication of a factor which approximately varies between 0.5 and 2.0, independent of attenuation. The first is a realistic value obtained by averaging over all the possible directions of arrival of vehicles     

Rain attenuation statistics useful for the design of mobilesatellite communication systems

We have investigated how rain attenuation statistics, necessary to design fixed satellite systems working at frequencies greater than 10 GHz, are transformed to those applicable to the design of mobile satellite systems working in the same frequency bands and weather conditions in the special case of vehicles driven in zig-zag patterns to simulate city streets. The vehicles' speed has been modeled as a lognormal random variable, a mathematical model derived from measurements performed in freeways or in city traffic. We have used a large number of rain-rate time series collected in Italy (Gera Lario and Fucino) and in Canada (Montreal) to simulate rain-rate spatial fields and radio links at 19.77 GHz along a 30.6° slant path. The simulations have shown that a receiving or transmitting terminal moving in zig-zag patterns may experience, in the long term and for a given attenuation, a smaller outage probability, compared to the fixed terminal. For a given rain attenuation, the ratio between the outage probability of the mobile system and that of the fixed system (probability extrapolation factor ξ) is estimated to be around 0.2-0.3 in the optimistic case in which the probability of encountering rain is the same for all observers (fixed or in motion)-a less optimistic estimate shows that the probability of encountering rain might be twice as large and that, as a consequence, the values of ξ mentioned must be doubled. Conservative values of ξ can be calculated by using average values of rain storm speed and vehicles and average distances covered in the rain by fixed and mobile terminals. The results are less sensitive to changes in the geometrical or other parameters of the simulations     

An overview of propagation factors influencing the design of mobilesatellite communication systems

A number of mobile satellite communication systems are currently being developed that do not make use of satellite constellations based on the traditional geostationary orbit used for communication satellites. This paper describes some of the propagation-related factors that influence the constellation for some of these systems, along with mitigation techniques that may be employed to overcome the dominant propagation-related impairments. For systems operating at VHF and UHF, the effects of mobile environment factors such as blockage and multipath are the dominant propagation factors in the link design. Mitigation techniques, such as satellite diversity, can be usefully employed to help overcome the effects of blockage, which may become increasingly severe at low elevation angles. The driving factor for constellation design is to provide a sufficiently high probability of multiple (dual or more) satellite visibility over the latitudes of interest     

超强FEC在大容量长距离光通信系统中的应用

介绍了光纤通信系统中所使用的前向纠错编码技术和超强前向纠错编码技术及实现,通过实际工程中的应用,指出了在大容量长距离光纤通信系统中使用超强纠错编码技术的优势。     

基于FEC的LDPC编码在远距离光通信系统中的研究

在研究超强FEC的LDPC编码在光通信中的应用性能分析的基础上,设计了采用超强FEC技术的OTU,给出了LDPC编码器与译码器具体设计,最后进行了实验方案分析和LDPC码型在远距离光通信系统中的仿真。     

高速光通信中的级联码设计与VLSI实现

本文设计了应用于光通信系统的RS(255,239)+BCH(2184,2040)级联码编解码电路。级联码系统中,RS码与BCH码速度的不匹配是影响性能的最大瓶颈,本文采用并行度为8的并行BCH编解码器来实现与RS码速度的匹配。推导了BCH编码器并行化方法,并利用子项共享的方法来减少子项的扇出,使每个子项的最大扇出数不超过10。利用并行伴随式计算和并行钱氏搜索来提高BCH译码器的吞吐量,同时充分利用截短码的特性使钱氏搜索时间减少了46%。级联码的编解码器已用TSMC 0.18-μmCMOS标准单元库方法实现,后仿真结果表明,在312.5MHz的时钟下,级联码能够正常工作,能实现2.5Gb/s的数据吞吐量。建立了基于Xilinx FPGA的测试验证平台,测试结果表明电路功能正确、工作正常。     

前向纠错码在高速光纤通信系统中的应用

介绍了前向纠错（FEC）技术在高速光通信系统中应用的必要性、特点、实现方式、以及其对系统性能的改善。     

A novel reliable and secure communication scheme for cognitive radio networks using concatenated kernel codes

Cognitive radio networks have emerged as a possible solution for the spectrum scarcity problem. Cognitive radio networks involve heterogeneous entities as part of it for facilitating spectrum sharing. Ensuring reliability and security in such scenario is inevitable for the licensed users (primary users) as well as for the unlicensed users (secondary users). To address the challenges of reliable and secure communication for the secondary users, in this paper, a novel reliable and secure communication framework is proposed. A class of group codes called concatenated kernel codes is used to achieve reliability and techniques of fundamental cutset and fundamental circuit to achieve security in terms of authentication of sender. It is shown that the proposed communication framework provides reliability mitigating the continuous interference of primary users and security by defending against the cryptanalytic attacks such as replay attack, related key attack, and man‐in‐the‐middle attacks. The theoretical basis of the proposed framework is validated, and its performance is evaluated through simulations.     

光通信系统中一种新颖的随机交织型级联码方案

基于LDPC码,提出一种新颖的随机交织型级联码(RICC,random interleaved concatenatedcode)方案。在编码阶段,根据LDPC码中不同度数的变量节点采用不同纠错能力的BCH外码,分别进行保护的思想进行集分割编码;在译码阶段,采用硬判决辅助软判决的联合迭代译码。不同于传统的单极型和交织型级联方式,它是一种根据LDPC码变量节点(VN)度数来决定交织深度,因而交织方式是随机的。仿真结果分析表明,在误比特率(BER)为10-8时,四集合分割的RICC-4P的净编码增益(NCG)比无分割的单级型级联码提高了0.15dB,比ITU-T G.709和G.975.1标准中的RS(255,239)、RS(255,239)+CSOC(n/k=7/6,J=8)级联码和开销为25%的正交级联BCH码的NCG分别提高了3.0、1.5和0.4dB,其纠错性能的提升得益于采用集分割保护和硬判决辅助软判决的联合迭代译码。     

Handover scheme for mobile cellular communication systems

A new scheme for minimising handover failure probability in mobile cellular communication systems, by exchanging channels between two mobiles moving in opposite directions across the endeavour area of adjacent cells is presented. The performance evaluation of the new scheme is carried out by computer simulation of a two cell model     

Personal communication systems (PCS)

Personal communication systems (PCS) represent a rapidly growing and increasingly important segment of the telecommunication industry. The goal of PCS is to provide truly personal, cost-efficient communication services to users through portable handsets. In this paper, we present a survey on the research and development in PCS, emphasizing several important aspects such as the PCS concept, service requirements, system architecture, operation, and management. Some ongoing field trials are described as well. We focus on the wireless and the mobility-related features of PCS, discuss their impact on the system design and performance, and provide an overview of different technology choices     

A new probability decoding scheme based on genetic algorithm for FEC codes in optical transmission systems

Based on the genetic algorithm(GA),a new genetic probability decoding(GPD) scheme for forward error correction(FEC) codes in optical transmission systems is proposed.The GPD scheme can further offset the quantification error of the hard decision by making use of the channel interference probability and statistics information to restore the maximal likelihood transmission code word.The theoretical performance analysis and the simulation result show that the proposed GPD scheme has the advantages of lower decoding complexity,faster decoding speed and better decoding correction-error performance.Therefore,the proposed GPD algorithm is a better practical decoding algorithm.     

Spectrally efficient MSK scheme for SCPC communication systems

A spectrally efficient scheme is described, for SCPC (single channel per carrier) communication systems, in which slightly modified MSK (minimum shift keyed) channels can be allowed to overlap spectrally, with a channel spacing equal to half the individual channel bit rate, without causing any crosschannel interference     

A new modulation scheme for IR-UWB communication systems

Since the poor performance of orthogonal binary Pulse Position Modulation (PPM) compared with binary Pulse Amplitude Modulation (PAM), this paper presents a new modulation scheme named Pulse Width Modulation (PWM) for Impulse Radio Ultra-WideBand (IR-UWB) communication systems. This modulation scheme uses pulses with equal amplitude and different widths to carry different information. The receiver employs differences between similarity coefficients among these pulses to distinguish different information. Bo...