一种新的导频符号辅助下的信道衰落设计方法

本文提出一种新的导频符号辅助下的信道衰落估计方法。它同时利用导频符号和数据符号进行信道衰落估计和补偿。而不同于传统的信道衰落估计只利用导频符号的信息。此方法具有实现简单,延时小的优点。针对１６ＰＳＫ和１６ＱＡＭ调制方式作了仿真,结果显示导频符号辅助下的１６ＱＡＭ的性能优于１６ＰＳＫ,采用信道衰落估计与相干检测结合的１６ＰＳＫ性能又好于采用差分检测的１６ＰＳＫ的性能。     

WCDMA上行链路中的一种有效的RAKE接收方案

在WCDMA系统上行链路中，提出把智能天线与RAKE接收机相结合，利用上行链路的帧结构特征，将各时隙的导频符号的扩频序列作为阵列处理部分的LMS自适应算法更新阵元权矢量的参考信号，来解决CDMA系统反向信道的容量受限问题。仿真实验结果表明该方法能显著提高系统的容量，且简单易行。     

功率控制对S-CDMA-HFC系统上行信道Erlang容量的影响

同步ＣＤＭＡ（Ｓ－ＣＤＭＡ）解决了双向ＨＦＣ系统的上行信道噪声和容量问题,基于Ｓ－ＣＤＭＡ的ＨＦＣ是新一代ＨＦＣ系统。从系统实现的角度来看,非理想功率控制会明显降低系统业务容量。本文简单介绍了Ｓ－ＣＤＭＡ－ＨＦＣ系统模型和上行信道概况,分析了非理想功率控制对Ｓ－ＣＤＭＡ－ＨＦＣ系统上行信道Ｅｒｌａｎｇ容量的影响,并给出了数值结果与结论。     

综合信道估计和卷积码的CDMA同频干扰消除技术

本文提出了一种多级ＣＤＭＡ同频干扰消除算法。算法采用周期性插入书籍码元的方法对反向信道特性进行精确的估计,使得的在反向信道上实现导频符号辅助的相干解调。算法采用Ｖｉｔｒｅｂｉ译码器的输出作为第一级判决结果重建干扰信号而不是常规的解扩以后重建干扰信号,由于综合信道估计和卷积编码提高了干扰信号重建的准确度,从而采用干扰消除技术后剩余干扰大幅度下降,系统时处并没有显著增加。数值结果表明综合信道估计和卷积     

一种新的OFDM后缀信号-PP

本文提出了一种可用于正交频分复用(OFDM)系统的新型后缀信号-导频后缀(PP:Pilot Postfix),并以此设计了PP-OFDM系统.PP信号由OFDM符号中的导频线性处理生成,它在接收端可以和OFDM符号中的导频相干合并.在此基础上本文给出了PP-OFDM信道估计、以及考虑了信道估值误差的数据符号估计算法.理论分析表明,相对于另外两种OFDM系统中常用的前/后缀信号-循环前缀/补零后缀(CP/ZP),PP信号可以提高信道估计性能.仿真表明,CP/ZP/PP-OFDM分别采用各自的最优导频功率分配参数时,PP-OFDM的误码率最低,这得益于PP-OFDM更好的信道估计性能.PP-OFDM的最优导频功率分配参数应通过二维搜索得到,ZP/PP-OFDM仅有一维参数可优化.     

一种基于SIR的DS-CDMA系统闭环功率控制算法

针对采用专用控制信道的DS－CDMA系统的上行链路,本文直接利用控制信道的导频符号进行SIR测量的闭环功率控制,并通过计算机仿真对链路的性能进行分析。仿真结果表明,由于编码交织及功率控制的共同作用,在链路达到一定误码率时,所需的信噪比随着信道衰落的增加而啬 缓慢;最佳的功能控制步长取决于信道衰落速率;功能控制命令的传输错误概率在小于10^-1时对链路性能影响较小。     

cdma1x无线子系统导频信道功率分配分析

分析了目前联通CDMA网络建设中的主要问题之一——导频功率分配问题。主要介绍了cdma 1x系统的信道类型，以及前向链路信道功率分配原则，并且对导频信道功率与无线网络覆盖和容量之间的关系进行了初步探讨。     

浅谈CDMA系统中导频功率的优化配置

在CDMA系统中，导频功率比是一个重要的工程设计参数，能否正确的选取导频功率比将直接影响系统性能和链路容量。文中就导频功率比对系统容量及平衡的影响进行了探讨和研究，给出了满足链路平衡条件下恰当的导频功率比范围。     

高速补充信道对cdma2000-1x前向链路功率分配的影响

分析了cdma2000-1x系统的前向信道发射功率分配。通过仿真试验及理论推导，给出了导频信道和业务信道信号质量之间的相互依赖关系并绘出导频信号和业务信道之间的相关性曲线：根据这种相关性曲线，从而发现使总发射功率最小的最佳导频功率；最后提出并分析了高速补充信道对cdma2000-1x前向链路功率分配的影响。     

跳频/多载波频率分集/扩频多址无线通信系统的研究

本文提出了一种跳频／多载波频率分集／扩频多址（ＦＨ／ＭＣＦＤ／ＳＳＭＡ）无线通信系统,给出了ＦＨ／ＭＣＦＤ／ＳＳＭＡ系统的发送和接收模型,对判惟变量统计特性进行了分析,然后对峰窝系统反向链路在理想定时和信道估计条件下用户平均接收误码率进行了仿真。结果表明,ＦＨ／ＭＣＦＤ／ＳＳＭＡ蜂窝通信系统具有较好的抗多径衰落能力,同单载波ＦＨ／ＳＳＭＡ系统相比其误码性能和频谱效率有显著改善。     

WCDMA上行链路一种新的参数优化方法

本文在研究了WCDMA上行链路导频信道辅助相干解调的基础上,提出了参数优化的一种新方法.根据给定信噪比下误码概率最小的准则,本文得到了理论上信道估计器最佳的平均长度和导频信道相对数据信道最优的功率比.     

相干OFDM系统中导引符号功率优化

在瑞利衰落信道下，本文研究了导引符号功率对相干OFDM系统性能的影响，计算了由于不精确信道估计引起的系统性能损失，优化分析了导引符号与数据符号功率比，并给出完整的最优功率分配数学表达式。理论分析和仿真结果给出了各种参数对最优功率比的影响，同时理论结果为系统设计提供了依据。     

Data/pilot combination strategies for Compass B1C signal acquisition

The new Compass B1C signal, with a power ratio of the data channel to the pilot channel of 1:3, adopts BOC(1,1) in its data channel; a new modulation, namely, a quadrature multiplexed binary offset carrier (QMBOC) in its pilot channel modulates the narrowband BOC(1,1) and the wideband BOC(6,1) components in phase quadrature with each other. To fully exploit the B1C signal and to improve the acquisition sensitivity in a degraded signal or an indoor environment, this paper proposes to combine the data and the pilot channels for B1C signal acquisition. The noncoherent, coherent, and differential coherent strategies are considered for application in the B1C signal. Considering the power inequality between the data and the pilot channels, the maximum signal‐to‐noise ratio combination (MRC) is utilized in these strategies to obtain an optimal combination. This paper also proposes to simplify the differential coherent strategy to obtain a better anti‐noise performance under stable conditions. The computer simulation results are given to verify the theoretical expressions, and some discussions with respect to the proposed strategies are provided.     

大规模MIMO系统中基于能效最大化的资源联合优化算法

针对信道条件未知的多小区大规模多输入多输出（MIMO）系统,提出一种对导频序列长度、导频符号功率以及数据符号功率进行联合优化的资源分配算法。采用最大比合并（MRC）接收,考虑电功率和导频污染的影响,并对最大传输功率进行约束从而建立起以能效（EE）最大化为目标的非凸函数模型。根据分数规划的性质,首先将分数形式转化成减式形式,进而分解成一系列凸函数之差（DC）的问题,最后采用交替优化算法联合调整 3 个变量从而达到能效最大化的目标。仿真结果表明,随着最大符号传输功率的增加,所提方案仍然能保持良好系统能效性能。     

Error Rate Analysis of Uplink MC-CDMA Systems under Imperfect Channel Estimation

Theoretical error rate performance of wireless communication systems are usually determined assuming that the perfect channel state information (CSI) is available at the receiver. However, in actual practice, the channel gains at the receiver are obtained via using some channel estimation (CE) techniques. Due to inherent presence of noise, the CE is not perfect resulting in the performance degradation. In this paper, we evaluate the error rate performance of an uplink multicarrier code-division multiple-access (MC-CDMA) system, considering different modulation techniques, where CE is performed using pilot symbol assisted (PSA) minimum mean-square error (MMSE) CE technique. The symbol error rate (SER) analysis of an uplink MC-CDMA system using multiuser detection techniques, such as MMSE and zero forcing (ZF), is presented under imperfect CE. Simulated results for SER are also shown to confirm the accuracy of the analytically derived results.     

Interference alignment scheme for massive MIMO system

The performance of massive multiple-input multiple-output （MIMO） system is limited by pilot contamination. To reduce the pilot contamination, uplink and downlink precoding algorithms are put forward based on interference alignment criterion. In the uplink receiving processing, the target function aligns the pilot contamination and the interference signals to the same null space and acquires the maximal space degree of the desired signals. The uplink receiving precoding matrix is solved on maximal signal to interference plus noise ratio （SINR） criterion considering the impact of the pilot contamination on channel estimations. The uplink receiving precoding matrix is used as the downlink transmitting precoding matrix. Exploiting the channel reciprocity, it is proved that, if the uplink receiving precoding matrix achieves maximal S1NR, the identical precoding matrix can be used in the downlink transmission and acquires maximal signal to leakage plus noise ratio （SLNR）. Simulations show that the spectrum efficiency of the proposed algorithm can reach about 1.5 times higher than that of popular matched filtering （MF） precoding algorithm, and about 1.1 times higher than multi-cell minimum mean square error （MMSE） precoding algorithm. The performance of the proposed algorithm can be improved approximately linearly with the increasing of the number of antennas.     

Pilot symbol assisted coding

Proposed is a novel technique, hereby referred to as pilot symbol assisted coding (PSAC), where a predetermined fraction of binary pilot symbols is interspersed with the channel-coded bits at the channel coding stage, instead of multiplexing the pilots with the data symbols at the modulation stage, as in classic pilot symbol assisted modulation (PSAM). It is demonstrated that the PSAC succeeds in gleaning more benefits from the pilot overhead investment, than just simply the capability of channel estimation such as in the PSAM technique.     

Power control in feedback communications over a fading channel

Pilot symbol assisted modulation and a minimum mean-square error (MMSE) channel predictor are used to employ feedback MMSE power control over a frequency nonselective slow Rayleigh fading channel. Feedback is assumed to be noiseless and delayless. First, the performance of the pilot symbol system using MMSE power control is derived in the case of the frame size of two. Lag error is noticed to cause severe performance degradation, even when the channel is very slowly fading. In order to decrease the lag error and to get a good system performance, the number of estimator coefficients is found to become quite large. The operating strategy of MMSE power control is studied by Monte Carlo simulations and compared to various strategies presented in the literature. Spectral efficiency of the pilot symbol system is increased by transmitting more than one data symbol in a given frame. Finally, the performance of the pilot symbol system using MMSE power control is derived in the case of an optimal frame size     

两路接收分集Turbo乘积编码PSAM系统的研究

提出具有两路接收分集Turbo乘积编码引导符号辅助调制(TPC-PSAM）的16QAM系统的实现方法。该系统将Turbo乘积编码和分集接收用于改善16QAM系统在平坦衰落信道中的性能。通过对衰落信道中的数值仿真，结果表明具有接收分集的TPC-PSAM系统比TPC-PSAM系统明显的改善，同时可以减小接收机在不同衰落信道中的性能差异。     

Error performance of differentially coherent detection of binary DPSK data transmission on the hard-limiting satellite channel

The error performance of differentially coherent detection of a binary differential phase-shift keying (DPSK) system operating over a hard-limiting satellite channel is derived. The main objective is to show the extent of error rate degradation of a DPSK system when a power imbalance exists between the two symbol pulses that are used in a bit decision interval. Consideration is also given to the DPSK error rate performance for the special case of {em uncorrelated} uplink and {em correlated} downlink noises at the sampling instants in adjacent time slots. Error probabilities are given as functions of uplink signal-to-noise ratio (SNR) and downlink SNR with different levels of SNR imbalance and different downlink SNR and uplink SNR as parameters, respectively. Our numerical results show that 1) as long as the symbols are equiprobable, the error probability is not dependent upon the downlink noise correlation, regardless of whether there is a power imbalance; 2) error performance is definitely affected by the power imbalance for all cases of symbol distributions; and 3) the error probability does depend upon downlink noise correlation for all levels of power imbalance if the symbol probabilities are not equal.