并行级联卷积码的最新进展

并行级联卷积码（Ｔｕｒｂｏ码）是近年来在编码理论上的一个重大突破，其性能与信道容量极限的差距可小于１ｄＢ。有着极其广阔的应用前景。这种编码方式的优异性能来源于其独特的码结构和迭代译码算法，使其成为一种接近随机编码的可译码。它的编译思想将对编码研究产生重要影响。本文将在编码结构，性能分析与码设计、简化算法及应用等方面对这种码的研究现状与前景作一综述。     

Ad Hoc网络技术研究进展

AdHoc网络现在是非常有吸引力的研究方向。本文介绍了Ad Hoc网络的定义、特点、体系结构、信道接入协议，最后分析了Ad Hoc网络面临的问题。希望本文能为进行AdHoc网络技术研究的人们提供一定的方便。     

天线与合路器的关系

主要探讨了在CDMA网络设计时,如何考虑空闲状态时终端的守候方式、终端业务请求时网络资源的分配方式以及跨载频硬切换的解决方案这3个方面的问题.     

Strain effects on optical properties of pyramidal InAs/GaAs quantum dots

Strain distribution and optical properties in a self-assembled pyramidal InAs/GaAs quantum dot grown by epitaxy are investigated. A model, based on the theory of linear elasticity, is developed to analyze three-dimensional induced strain field. In the model, the capping material in the heterostructure is omitted during the strain analysis to take into account the sequence of the fabrication process. The mismatch of lattice constants is the driving source of the induced strain and is treated as initial strain in the analysis. Once the strain analysis is completed, the capping material is added back to the heterostructure for electronic band calculation. The strain-induced potential is incorporated into the three-dimensional steady-state Schrödinger equation with the aid of Pikus–Bir Hamiltonian with modified Luttinger–Kohn formalism for the electronic band structure calculation. The strain field, the energy levels and wave functions are found numerically by using of a finite element package FEMLAB. The energy levels as well as the wave functions of both conduction and valence bands of quantum dot are calculated. Finally, the transition energy of ground state is also computed. Numerical results reveal that not only the strain field but also all other optical properties from current model show significant difference from the counterparts of the conventional model.     

数字磁记录的信道模型及RLL码的信道容量

游程长度受限码（ＲＬＬ码）又称（ｄ，ｋ）码，在数字磁记录中用于调制，至今，已有许多学者对此进行了研究，但大多数有关此码的信息论模型是无噪声的，基于Ｈｅｅｇａｒｄ模型。本文撮一种有噪声的离散信道模型，并估计了信道容量的上下限。     

雷达发射信道中的噪声

本文介绍了经常被人们忽视的，有关发射信道中的噪声问题，提出了降低噪声的方法以及在处理信道噪声时应注意的几个方面。     

一种智能天线的盲校正方法

实现智能天线技术需要解决的一项关键问题是通道失配的校正，已有的通道校正方法未考虑实际通道间存在处理时延差异。本文分析了一种盲校正方法的原理，仿真结果表明该方法在通道间存在时延差异的情况下已失效。进而，提出了一种改进的盲校正方法。结合DS—CDMA信号的特点，该方法首先补偿了各通道间的时延差异，并在此基础上结合原有的盲校正方法。仿真实验证明了它的有效性。     

第三代移动通信智能天线的研究现状及发展趋势分析

本文首先简单地介绍移动通信发展以及第三代移动通信（3G）的技术特征和实现目标，并阐述了如何用多址来解决通信资源紧缺的问题，随后重点讲述智能天线的定义、优点、组成、工作原理、信道模型以及要解决的关键技术问题和发展现状。最后，提出了智能空分多址的概念，并对智能天线未来的发展进行了分析和预测。     

Performance analysis of an adaptive receiver structure for digital mobile communications

In this paper we investigate the performance of a combined estimation/equalization technique for the mobile radio channel, assuming a GSM-recommended transmission format (narrowband TDMA with midamble, recommendation 5.04) and MSK modulation scheme. Channel estimation is performed via correlation of the received signal with a suitably modulated replica of the transmitted midamble. Equalization is then obtained by means of a maximum likelihood sequence estimation (MLSE) scheme in the form of a so-called Viterbi equalizer. Our analysis provides theoretical results concerning the bit error rate (BER) attained by the receiver for a given stationary multipath channel model. Simulation results are also presented in order to integrate and validate the theory.