MQAM调制在个人通信系统中的综合性能分析

本文从移动通信系统总体设计的角度出发,建立了移动通信系统受共道干扰影响时的系统分析模型,并结合分集接收技术,综合分析了在高斯白噪声(AWGN)、共道干扰(CCI)及特定衰落(Rayleigh、Ricean、Nakagami)环境下,采用高效频谱调制技术MQAM时的系统误码率性能,并导出了误码率的一般化近似计算公式.最后,通过对计算机仿真结果的分析,我们得到了一些结论.     

MPSK调制在个通信系统中的综合性能分析

本文讨论了高效频谱调制MPSK在个人通信系统中的应用,并对其性能做了综合分析。文中先建立了MPSK调制信号从发送到接收的系统模型,再在综合考虑CCI共道干扰,三种非频率选择性衰落（Rayleigh,Rician,Nakagami)及加性高斯白噪声等影响因素的基础上,结合两种分集接收（选择式合并,最大比值合并)技术,给出了MPSK应用于个人通信时的误码率计算的通用近似公式。     

高效调制MQAM数字移动通信系统的性能分析：（Ⅰ）系统模型

本文导出了一种较完备的高效调制ＭＱＡＭ数字移动通信系统的基带等效模型。所考虑的移动通信系统中包含频率选择性多径瑞利衰落信道、同频道干扰、邻频道干扰和加性高斯白噪声。给出了相应的计算机模拟结果。     

高效调制MQAM数字移动通信系统的性能分析：（I）系统模型

本文导出了一种较完备的高效调制ＭＱＡＭ数字移动通信系统的基带等效模型。所考虑的移动通信系统中包含频率选择性多径瑞利衰落信道、同频道干扰、邻频道干扰和加性高斯白噪声。给出了相应的计算机模拟结果。     

Rayleigh衰落信道下多载波DS-CDMA系统性能分析

本文基于多载波传输技术，提出了一种多载波码分多址模型。并在Rayleigh衰落信道下对其误码性能进行了分析。分析及仿真结果表明，系统具有降低多址干扰的能力，同传统的单载波直接序列码分多址系统相比，能支持更大的用户容量。本系统能满足第三代移动通信系统对高速数据传输的要求。     

数字蜂窝移动通信系统的调制技术

本文主要讨论数字蜂窝移动通信中的调制解调问题。在指出其特点后,阐明线性调制及恒包络连续相位调制两类方案,着重介绍恒包络连续相位调制中的GMSK 调制。     

低轨道卫星移动通信的调制解调方式

为克服卫星移动通信中存在的大多普勒频移,本文介绍一种全新的调制解调方式--双信道调制解调.文中讨论了它在低轨道卫星移动通信中的性能,给出了数值结果,并与CPSK、DPSK和DDPSK进行了比较.     

移动通信中的π／4QPSK调制解调技术及DSP实现

介绍了一种比ＧＭＳＫ具有更优的频谱特性，频谱利用率及更强抗衰落性能的线性窄带调制解调技术（π／４ＱＰＳＫ），并给出了它的ＤＳＰ实现和相应的性能。     

Performance Analysis of Cellular Mobile Communications under Multipath Interference

In a radio communication environment, no matter whether signal is transmitted outdoors or indoors, the phenomenon of multipath interference is unavoidable. Therefore, it is necessary for us to thoroughly study the effect of multipath interference on cellular mobile systems. In this paper, we first investigate the effect of multipath interference on the performance of a single cell system with finite users. In order to use the Markov chain method, a system model with 2-dimensional state vector is presented. With his model, the system performance under multipath interference has been successfully derived. Next, an extended-slot method to reduce the multipath interference triggered by LOS packets occurring in the previous slot is proposed. Numerical results show that this method can remarkably enhance the system performance. Finally, we further analyze the combined effect of co-channel interference and multipath interference on the performance of multicell systems. Numerical results show that the system performance suffers some degradation compared to the single cell environment. However, the degradation under typical environments with path-loss exponent around 4 is insignificant.     

瑞利信道MQAM传输误码性能数值分析——移动通信中多电平正交振幅调制方案的优化考虑(二)

分析了在含有高斯白噪声的Rayleigh衰落信道中,矩形星座图MQAM、圆形星座图MQAM的传输误码性能,给出相应的误码率计算公式,并进行计算机数值分析。为在移动通信中MQAM调制方案的优化选择提供了分析结论。     

P－TCM在卫星移动通信信道上的性能

实用化网格编码调制（Ｐ－ＴＣＭ）方案能够利用同一芯片实现不同码率的网格码之编译码过程，其性能在加性高斯白噪声信道上与ＵｎｇｅｒｂｏｅｃｋＴＣＭ码相比差别不大。本文针对编码率为２／３的６４状态Ｐ－ＴＣＭ码，从理论上计算了在相干检测和差分检测两种情况下，该码在Ｒｉｃｉａｎ信道上和轻微遮挡的Ｒｉｃｉａｎ信道上的误比特率上、下限或渐进曲线，并且给出了相应的计算机仿真结果。结果表明，当误比特率为１０－３时，该码在上述信道上约有３．４ｄＢ～５．２ｄＢ的编码增益。     

Dynamic Base Station Selection for Personal Communication Systems with Distributed Control Schemes

Distributed control schemes allow base stations in personal communication systems to be placed at locations corresponding to high expected traffic. This flexible base station placement creates significant overlapping coverage areas that can be utilized to improve system performance [1]. A new technique for dynamic base station selection in systems with overlapping cells is considered and its effect on traffic performance is characterized. The technique realizes robust performance for personal communication systems in fluctuating and heavily tapered traffic. A mathematical analysis based on a state transition model is used to evaluate performance of a system that employs the proposed technique. The results indicate that improved blocking probability and carried traffic performance are obtainable. Computer simulations were undertaken confirm the analytical results.     

Optimization of MQAM Modulation Schemes in Mobile Communications（Ⅱ）—Analysis of MQAM BER Performance in Rayleigh Channel

The transmission error code performance of square MQAM and star MQAM modulation schemes for the AGWN Rayleigh fading channel is analyzed.The corresponding BERformulas and computer aided numeric results are given.Therefore it provides a theoretical basis for choosing MQAM modulation schemes in mobile communications.     

采用预判决信息的LDPC码编码调制方案性能研究

低密度奇偶校验(LDPC)码是Turbo码以外另一种性能接近香农限的好码.本文将LDPC码与比特交织编码调制(BICM)相结合,首先给出了在不使用传统解调器与译码器之间迭代的情况下8PSK调制方案在AWGN信道和Rayleigh衰落信道中的性能(简称为无迭代方案).然后提出了一种新的接收端解决方案:首先对接收符号进行预判决,判决信息被用来调整解调器,从而在一定程度上弥补了不使用解调器与译码器之间迭代所造成的性能损失,并且相对于无迭代方案接收端复杂度几乎没有变化,但性能却有所提高.这说明原有比特度量产生方法并不是最佳的,该文使用预判决信息的方案给出了一个改善的思路.通过仿真结果可以得到结论:使用本文所提出的方案在AWGN信道和Rayleigh衰落信道中都可以在不增加复杂度的情况下提高性能.     

用于移动通信系统的发送分集技术

在分析接收分集技术最大比率接收合并(MRRC)方案的基础上，介绍了一种两分支发送分集方案。该方案采用2个发射天线、1个接收天线，可提供与1个发送天线、2个接收天线情况下的MRRC方案相同的分集增益。由于发送符号采用了正交性设计，该发送分集方案在接收端可以将不同的发送符号分离开来，分别进行最大似然检测。仿真结果表明，运用分集技术可大大改善无线通信系统的性能，且该方案和一发两收的MRRC方案性能相似、计算复杂性相同。该发送分集方案能更好地应用于移动通信系统。     

Trellis Coded Hybrid Selective Repeat ARQ Schemes for Point-to-Multipoint Communication over Rayleigh Fading Channels

In this paper, the hybrid selective repeat (SR) automatic repeat request (ARQ) scheme using trellis coded modulation (TCM) proposed by Tellambura and Bhargava [21] is generalized to point-to-multipoint communications for Rayleigh fading channel. Analytical expressions are derived for the throughputs of the point-to-multipoint communication schemes with and without code combining technique. Numerical results show that the protocol using code combining technique yields better throughput than the protocol without code combining and the throughputs decrease when the number of receivers and the value of erasure threshold increase. When the number of receivers equals 1, the scheme without code combining becomes the point-to-point communication scheme proposed in [21].     

第四代移动通信系统的调制技术

现有通信系统的调制技术限制了信号速率的进一步提高,即将推出的第四代(4G)移动通信系统需要更优良的调制技术。正交频分复用(OFDM)技术是很受欢迎的高速率无线通信技术,结合OFDM的调制技术将在4G系统中得到广泛应用。文中概要介绍了4G系统的特点及关键技术,然后系统介绍了OFDM多载波原理,最后重点介绍了多载波码分多址(MC-CDMA)和正交频分复用时分多址(OFDM-TDMA)两种多载波调制(MCM)技术。