数字电视的数字调制技术

本主要介绍数字有线电视网上、下行信道频谱的划分，各种数字调制方法、性能特点和优缺点比较。     

Delay analysis and dynamic tuning of an acknowledged mode radio link control protocol

In this paper, in-sequence delivery delay of an acknowledged mode radio link control (AM-RLC) protocol in wideband code division multiple access (W-CDMA) networks is studied. Two special protocol phenomena, duplicated retransmission, and delayed acknowledgment, are reported. A two-step dependent Markov chain is adopted to model the AM-RLC protocol. The in-sequence delivery is evaluated by means of an analysis through tracking the transmission status of a specific packet data unit (PDU) and its blocking PDUs. Analysis results indicate that in-sequence delivery delay is approximately linear with frame error rate. Analysis results also exhibit that in-sequence delivery delay is highly related to status report interval. Based on this observation, a dynamic AM-RLC scheme is proposed. The proposed AM-RLC scheme dynamically changes status report interval according to channel status. Extensive simulations are carried out to verify the effectiveness of the proposed scheme. It is found that the proposed scheme can reduce status report without penalty to in-sequence delivery delay.     

第三代移动通信系统中的多速率方案

多速率方案考虑如何以灵活、有效的方式将不同速度和质量要求（ＱｏＳ）的业务进行复用。以３ＧＰＰ制订的Ｗ－ＣＤＭＡ Ｒｅｌｅａｓｅ’９９规范中的多速率方案为基础,分析了第三代移动通信系统中上／下行链路多速率方案的原理与特点。     

Equalization Based Receivers for Wideband MIMO/BLAST Systems

This paper focuses on the usage of Equalization-Based receivers for Wideband Code-Division Multiple Access (WCDMA) Multiple Input, Multiple Output (MIMO) Bell Labs Layered Space Time (BLAST)-type systems. The main receivers on trial are the Zero-Forcing and Minimum Mean Square Error (MMSE) algorithm-based receivers and their variants, employing Parallel interference cancellation (PIC) and Iterative Partial Cancellation (IPC) schemes. To assess its performance in an existing system, the uncoded Universal Mobile Telecommunications System (UMTS) High-Speed Downlink Packet Access (HSDPA) standard was considered (using solely QPSK modulation) alongside the reference UMTS environments. The BER performance is assessed both by simulation and by semi-analytical processing.     

Efficient VLSI Architectures for Multiuser Channel Estimation in Wireless Base-Station Receivers

This paper presents a reduced-complexity, fixed-point algorithm and efficient real-time VLSI architectures for multiuser channel estimation, one of the core baseband processing operations in wireless base-station receivers for CDMA. Future wireless base-station receivers will need to use sophisticated algorithms to support extremely high data rates and multimedia. Current DSP implementations of these algorithms are unable to meet real-time requirements. However, there exists massive parallelism and bit level arithmetic present in these algorithms than can be revealed and efficiently implemented in a VLSI architecture. We re-design an existing channel estimation algorithm from an implementation perspective for a reduced complexity, fixed-point hardware implementation. Fixed point simulations are presented to evaluate the precision requirements of the algorithm. A dependence graph of the algorithm is presented and area-time trade-offs are developed. An area-constrained architecture achieves low data rates with minimum hardware, which may be used in pico-cell base-stations. A time-constrained solution exploits the entire available parallelism and determines the maximum theoretical data processing rates. An area-time efficient architecture meets real-time requirements with minimum area overhead.     

Interference Suppression Consisting of Pre-distortion Filtering and Selective Transmit Diversity

In this paper we present and evaluate a pre-distortion (PD) scheme for the downlink of Wideband-code division multiple access (W-CDMA) systems considering a Rake in the receiver in order to exploit multipath diversity. Its performance is compared with schemes without the PD at the base station (BS), and combined with a transmit diversity (TD) scheme to improve the performance by exploiting spatial diversity. It is shown that the proposed PD scheme allows receivers (Mobile Stations) with very low complexity, contrarily to the case where a post-processing multi-user detector (MUD) approach is adopted to improve the performance. Therefore, the proposed PD scheme can be seen as an alternative to post-processing schemes.

W-CDMA/cdma2000/GSM三频/三模移动台射频模块的研究

针对移动通信领域出现的多种模式和多个频段共同存在和使用的形势，提出了合理的W-CDMA／cdma2000／GSM三频／三模的移动台射频模块的设计解决方案，并在6层PCB板上研制了该三频／三模射频模块，其结构简洁，体积小，性能优良。在测试中严格按照3GPP和3GPP2的技术标准进行射频模块的各项指标测试，所测的各项指标均达到了3GPP和3GPP2的相关技术标准。     

用于W-CDMA移动终端的开槽微带双频贴片天线设计

该文针对W-CDMA移动终端天线的指标要求,给出一种微带开槽贴片双频天线的设计,它分别谐振在移动终端的收发频段。这种结构的天线具有体积小、重量轻、与载体共形、制造简单、成本低等优点。在设计过程中,进行了计算机仿真分析,并测试了天线驻波、增益、极化等指标。     

W-CDMA系统中基于串并混合相关的多径搜索器的FPGA实现

在DS-CDMA(包括W-CDMA)系统中,Rake接收机可以分离出信号在时间上形成的多径,通过合并同一期望码在各接收路径上的信号,能有效地克服多径衰落对系统性能产生的严重影响.Rake接收机设计上的一个重要问题是,如何准确的搜索到具有足够大SIR的多径分量.本文主要研究W-CDMA系统中NodeB上的利用串并混合相关器进行多径搜索的原理及其FPGA实现.     

快速Lagrange算法在双速率多用户检测器的功率控制中的应用研究

本文提出了一种快速Lagrange算法,并将它应用于宽带码分多址扩频通信双速率多用户检测器的功率控制中,从而使系统在达到不同的信扰比的条件下,各个用户的发送功率之和最小。本文分析了用该算法对双速率多用户检测器进行最小发送功率控制的基本理论和实际性能,探讨了该算法中相关参数的确定方法。该算法利用平均和反馈技术加快了Lagrange算法的收敛速度,因此有较好的实时性。仿真结果表明与快速随机功率控制算法相比,快速Lagrange功率控制算法可以提高双速率多用户检测器输出信号的平均信扰比,降低信扰比的平均偏差,提高达到信扰比要求的用户数量。