基于DVB-C具有增益补偿的自适应均衡器设计

采用一种具有增益补偿的自适应均衡器的设计方法,可直接利用均衡器产生的误差自适应地补偿输入信号,不需要单独的自动增益控制电路,有效地减小了QAM解调器的复杂度.MATLAB系统仿真结果表明,采用这种方法设计的自适应均衡电路能够在接收端纠正传播过程中的信号畸变.     

HSDPA与R99/R4混合组网容量规划

对WCDMAR99/R4网络与HSDPA网络可提供的容量分别进行分析;根据HSDPA的技术特点,对HSPDA与R99/R4混合组网后提供的各类语音、数据业务做出容量规划。     

单片式视频点播终端的设计与实现

主要介绍目前最新型的单片机顶盒，此单片式方案采用了LSI Logic公司的SC2000芯片，并具体描述了其硬件及软件的设计与实现。     

A simplified exact expression of SEP for cross QAM in AWGN channel from M × N rectangular QAM and its usefulness in Nakagami-m fading channel

This paper derives a simple exact expression of symbol error probability (SEP) for general order cross QAM constellation in the presence of additive white Gaussian noise (AWGN) channel. The key idea is to obtain this novel expression from a simple analysis of the corresponding rectangular QAM. The analysis of the expression involves simple one dimensional Gaussian Q functions unlike other complex SEP expressions. A simple tight bound approximation of the proposed exact SEP is also given, which provides performance improvement over the existing SEP approximations, particularly for low signal to noise ratios (SNRs). Also, with the help of simulation results, we show that the proposed approximation is in excellent agreement with the exact SEP curve. Moreover, the proposed expressions prove to be useful for accurate estimation of the SEP in Nakagami-m fading channel, including the special case of Rayleigh fading (m = 1).     

Signal Space Diversity Augmented Space Time Block Coded Communication System

In this paper we propose the combination of space-time diversity techniques and signal space diversity, in order to improve communication system performance. Specifically, we use prior knowledge of the channel behavior to design a mapping algorithm to generate a two-dimensional constellation with the same number of symbols as MPSK constellations currently used in coherent space time block coding applications, to demonstrate that superior performance can be achieved. This is accomplished by constructing a two-dimensional map that results from the minimization of the estimated symbol error probability when transmission occurs in a fading environment. System performance for each each mapping is assessed in quasi-static Rayleigh fading channels.     

QAM载波频偏估计的非线性变换分析

针对一类无数据辅助的非线性最小均方(NLS)载波频偏估计算法进行研究,讨论了其针对QAM信号的应用。通过最小化其估计方差,讨论了其基于信噪比信息的最佳非线性变换,随后给出不同信噪比下的近似算法,同时提出一种中高信噪比下的简化算法,仿真结果表明算法性能比传统的四次方算法有明显的改进。     

16QAM调制算法及其DSP实现

正交振幅调制技术（QAM）由于其高的频带利用率和相对低的误码率而被定为很多数字通信系统的数字传输标准.该论文讨论了16QAM调制原理,用软件产生16QAM信号的算法及其基于DSP软件编程实现.     

OFDM信号的盲侦察技术分析

正交频分复用传输系统,以其可对抗频率选择性衰落,高频谱利用率等优点,得到了广泛的应用。论述了正交频分复用(OFDM)信号非协作接收中的某些关键算法,研究了基于循环前缀的符号同步算法及最大联合似然估计(ML)算法、基于高阶累量的OFDM信号调制样式识别算法,解决了OFDM信号和常规通信信号之间的类间信号识别问题。仿真结果进一步说明了该方法的有效性。     

一种改进的QAM载波恢复方法

文中提出了一种新的QAM载波恢复环路结构。在此结构中频率检测和相位检测同时进行,在鉴相阶段引入了改进的加权直接判决（MWDD）算法。经仿真实验验证此方法提高了整个载波恢复环路的捕获速度,并使载波环路的相位抖动有所减小,16-QAM载波环路最大可以捕获11%符号率的频偏。     

高性能数字电视QAM均衡器VLSI结构设计

本文设计了一种适用于高清晰数字电视(HDTV)接收芯片的全数字正交幅度调制器(QAM)的均衡器。该均衡器由前馈滤波器、误差判别电路和系数更新电路以及后馈滤波器构成。该均衡器采用了常模算法(CMA)和判决导引最小均方算法(DD-LMS)相结合的算法。重点给出了均衡器的VLSI实现、两种算法间切换的依据、步长的选择以及抽头系数的确定。同时在电路上采用了逻辑简化、重编码、电路时分复用等简化和优化方法来实现性能、面积和功耗的折衷。