Simulation of LDPC Codes over WCDMA Downlink Channels

LDPC码是一类靠近Shannon限的高效信道编码,在AWGN信道下具有非常优越的性能。在讨论了LDPC码的基本原理之后,构建了基于LDPC码的WCDMA下行链路,改进了LDPC码的译码过程。仿真结果表明,在高速传输速率下(384kbit/s),不规则LDPC码具有优于Turbo码的性能,这对于LDPC码应用到复杂无线通信系统中具有重要意义。LDPC codes, which have good performances over AWGN channel, are the efficiently channel coding of near Shannon limits. After describing elements of LDPC codes, LDPC coded WCDMA downlinks were constructed, meanwhile, decoding process was improved. In high rate condition (384kbit/s), simulating results show that performances of irregular-LDPC codes are than that of Turbo codes. It is important value for LDPC coding in complex wireless communication systems.教育部新世纪优秀人才计划(NCET-04-0601);; 福建省科技重点项目(2006H0039)

基于EESM的车载网络仿真建模

车载自组织网(VAnET)作为智能交通系统的重要技术,受到越来越多的关注,本文提出一个新的基于指数有效SInr映射(EESM)的车载网络仿真平台,仿真结果表明,新的建模能够精确再现链路级误包率性能,比传统平台有更高的精确度

Optimal sub-carriers power allocation in MC-DCSK communication system

研究了多载波差分混沌移位键控(MulTI-CArrIEr dIffErEnTIAl CHAOS SHIfT kEyIng,MC-dCSk)调制中的子载波功率分配问题,基于功率分配模型,推导了MC-dCSk以子载波功率为参数的误比特率(bIT ErrOr rATE,bEr)表达式,基于该表达式,建立了最小化误比特率的最优化问题,并用凸优化方法获得了子载波最优功率的分配策略。通过仿真,比较了最优功率分配与等功率分配情况下,MC-dCSk在加性高斯白噪声(AddITIVE WHITE gAuSSIAn nOISE,AWgn)和rAylEIgH多径衰落信道下的性能,仿真结果验证了最优功率分配策略对系统性能的重要改进,尤其当子载波数较大时,其性能增益更为明显。In this paper,power allocation strategy on sub-carriers of Multi-carrier Differential Chaos Shift Keying( MC-DCSK) is studied.At first,the MC-DCSK system model with power allocated reference and information sub-carriers is presented.Then bit error rate( BER) expression of sub-carriers power allocated MC-DCSK system is derived.Based on the BER expression,the optimal sub-carriers power allocation strategy is obtained by convex optimization.The BER performance of the sub-carriers power allocated MC-DCSK system is evaluated and compared with the conventional MC-DCSK system with equal power allocations under additive white Gaussian noise( AWGN) and Rayleigh multipath fading channels.Simulation results confirm the significant advantages of the optimal sub-carriers power allocation when the number of sub-carriers is large.重庆工程学院校内自然科学基金(2013xzky06)~

Performance analysis of CS-DCSK over Nakagami-m fading channels

码复用差分混沌移位键控(COdE-SHIfTEd dIffErEnTIAl CHAOS SHIfT kEyIng,CS-dCSk)是一种dCSk的改进方案,其消除了接收机的延时电路,简化了系统实现。为了研究在一般化的多径衰落信道下的性能,基于高斯近似(gAuSSIAnAPPrOXIMATIOn,gA)方法分析了CS-dCSk在nAkAgAMI-M衰落信道下的误比特率(bIT ErrOr rATE,bEr)性能,给出了bEr的数值积分解。计算机仿真验证了分析结果,比较了不同信道参数M条件下的误比特率性能,并分析了原因。The code-shifted differential chaos shift keying(CS-DCSK) is an improved scheme of DCSK,which eliminates the delay circuits in receiver.It simplifies the implementation of system.For the study of the performance of CS-DCSK over the generalization multipath fading channels,based on Gaussian approximation(GA) the BER performance is analyzed over Nakagami-m fading channel.The expression of bit error rate(BER) is presented.Simulation results and numerical results show that the analyzed results are well consistent with the simulation results.And the BERs of different channel parameter m are compared and the reasons are analyzed.国家自然科学基金(61001073)---

Cooperative coded partial retransmission scheme based on link adaptive technology

在协作编码部分重传(COdEd PArTIAl rETrAnSMISSIOn,CPr)机制的基础上,引入链路自适应技术,通过在中继节点获取链路状态信息后,选择调制编码模式,实现自适应协作传输。仿真结果表明,在不降低系统吞吐量的情况下,改善了bEr性能,在吞吐量为0.19时,自适应调制的CPr机制相对于直接传输的CPr增益约为4.5 db。在bEr为10-3时,自适应调制的CPr协议相对于非自适应CPr协议增益约为2 db。In this paper,the cooperative Coded Partial(CPR) Retransmission scheme based on link adaptive technique is proposed.Utilizing the link state information at the relay node,the optimized-modulation and code mode of relay node is chosen.The simulated results show that Bit Error Rate(BER) performance of the proposed system is improved without sacrificing the system throughput.The BER of the proposed scheme has about 4.5 dB gains compared with that of the direct transmission at throughput of 0.19,Moreover,the proposed scheme obtains about 2 dB compared with the non-adaptive scheme at BER of 10-3.重庆市科委攻关项目(CSTC;2009AA2037)---

Research on coexistence between CS-DCSK UWB and narrow-band communication systems

分析了密集多径环境下码复用差分混沌移位键控(COdE-SHIfTEd dIffErEnTIAl CHAOS SHIfT kEyIng,CS-dCSk)超宽带(ulTrA WIdEbAnd,uWb)通信系统在单个和多个窄带干扰(nArrOW bAnd InTErfErEnCE,nbI)信号下的比特误码率(bITErrOr rATE,bEr)性能。建立CS-dCSk uWb系统仿真模型,并通过采样扩展方法推导出bEr的表达式,从而得到系统在不同干扰条件下的bEr性能。分析和仿真结果表明,nbI信号对系统有明显干扰作用,但系统性能在不同频率干扰下保持稳定。The performance of code-shifted differential chaos shift keying(CS-DCSK) ultra wideband(UWB) communication system under single or multiple narrow band interferers is analyzed in dense multipath environments.The bit error rate(BER) is derived on the basis of the sampling expansion approach under different interference strengths.The simulations and analyses demonstrate that the NBI signal interferes significantly the performance of system.However,the system performance keeps stable under interferer with different frequencies.国家自然科学基金(61001073;60972053); 欧盟FP7(294923)~

Study of UWB System based on Adaptive PPM Modulation

通过软件仿真,文中提出自适应PPM调制的uWb传输技术。它是建立在信道估计的基础之上,通过接收端对收信号的bEr统计,利用反向信道将信道状态信息传送给发送端,使其根据误码率要求自适应地改变的位移量dPPM,以满足在接收端误码率的要求下,提高了系统的传输效率。该方法为uWb通信系统中克服信道衰落开辟了一条新思路。The UWB transmission techniques based on adaptive PPM modulation(AM) is proposed through software simulation.It is established on the basis of channel estimation,and by using a feedback channel to send the channel state information (CSI)to transmitter,dPPM is adaptively adjusted according to BER requirement.AM could improve the spectral efficiency(SE)of UWB in satisfying the requirement of received BER.This method opens up a new way for overcoming the fading channel in UWB communication system

差分混沌移位键控在水声通信中的应用

水声信道作为目前已知最严酷、最复杂的无线通信信道之一,具有强多途干扰、时—频率双扩展、高噪、带宽窄等特征。水声信道的时变特性,使得估计与跟踪信道很困难,因此,研究无需信道估计与均衡的非相干稳健水声通信调制方法具有重要的意义。首先介绍了基于正交频分复用(OFDM)和扩频调制的水声调制技术的研究进展,然后,分析了差分混沌移位键控在水声信道下的可行性,提出了两种基于OFDM的多载波差分混沌移位键控方案,给出两个方案的调制解调器原理。在时—频双扩展信道和水声信道下,对两个方案进行了性能仿真和分析。性能结果表明所提出的方案在水声信道下具有良好的稳健性

Applications of LDPC Codes on GF (2--2) in Deep-space Communications

提出了一种近似等效信道模型,实现了gf(22)域上的ldPC码在深空通信系统中的嵌入设计。仿真结果表明:当数据帧长为1784bITS,bITErrOrrATE(bEr)为2x10-6,采用ffT-bP译码算法,50次迭代时,gf(22)域上的ldPC码相比rS码与卷积码级联码具有4.8db的编码增益;如果采用MAX-lOg-bP简化译码算法,10次迭代时,前者仍然能获得约3.8db的增益,且复杂度可以接受。An approximate equivalent channel model was proposed to realize the design of LDPC codes on GF(22) embedded in deep-space communication systems.Simulation results show that an LDPC code on GF(22) obtains 4.8 dB coding gain compared with a serial concatenation of a RS code with a convolutional code using the FFT-BP decoding algorithm with 50 iterations,when data block size is 1784bits,ber 2*10-6.However,based on the MAX-LOG-BP simplified algorithm with 10 iterations,the former has also about 3.8 dB gain,and the complexity can be accepted.国家自然科学基金(60972053);教育部新世纪优秀人才支持计划项目(NCET-04-0601

Performance of FM-DCSK UWB for wireless body area network

超宽带(ulTrA WIdE bAnd,uWb)技术具有低功耗、抗多径能力强等特点,已被无线体域网(WIrElESS bOdy ArEAnETWOrk,WbAn)作为一种候选传输技术,而调频差分混沌位移键控超宽带(frEQuEnCy-MOdulATEd dIffErEnTIAl CHAOSSHIfT kEyIng ulTrA WIdEbAnd,fM-dCSk uWb)实现简单,在接收机端不需要信道估计、信道均衡和rAkE接收,也得到了广泛的研究。主要对fM-dCSk uWb技术在WbAn的体内到体表、体表到体表和体表到体外3种信道模式下的性能进行了计算机仿真,并对影响其系统性能的积分时间和保护间隔2个参数进行了分析,仿真结果表明,fM-dC-Sk uWb技术用于WbAn信息传输是可行的。Ultra wideband(UWB) technique is adopted by the wireless body area networks(WBAN) as one of the most promising candidates due to its low power spectral density and high robustness against multipath fading.FM-DCSK UWB has gained much attention for its merits of no requiring channel estimation,channel equalization and rake reception in the receiver side.In this paper,the feasibility of FM-DCSK UWB over different WBAN channels,including implant to body surface,body surface to body surface and body surface to external,is investigated.Two system parameters directly affecting the system performance,i.e.,integration interval and guard interval,are carefully investigated respectively.Simulation results show that FM-DCSK UWB can be used as a feasible transmission technology for WBAN.国家自然科学基金(61001073;60972053)~