频率选择性衰落信道下STBC—DFDM系统的性能

本文将基于平衰落信道提出的空时块编码（STBC）方案应用到OFDM系统中,理论分析和仿真证明在理想信道估计下这种STBC-OFDM系统在频率选择性信道下能够获得对应的STBC在平衰落信道下的性能。     

空时分组编码技术在OFDM系统中的应用

介绍了空时分组编码，正交频分复用原理以及STBC—OFDM的一般系统模型。阐述了STBC—OFDM系统的性能和当前对STBC—OFDM技术研究取得的进展，最后时STBC—OFDM技术在未来移动通信中的研究方向做了前景展望。     

STBC-OFDM系统的半盲信道估计

STBC-OFDM系统中进行最大释然译码需要已知信道状态信息.提出一种用于3/4速率空时分组码OFDM系统的半盲信道估计方法.首先利用此系统的结构特点引入子空间盲估计技术进行信道估计,为解决子空间方法固有的模糊性问题,提出了一种使用少量导频符号的方法来估计模糊因子.仿真结果显示,本文提出的半盲信道估计方法相对于非盲估计方法具有更高的频谱效率和更好的估计性能.     

Performance analysis of visible light communication using the STBC-OFDM technique for intelligent transportation systems

Visible light communication (VLC) applied in an intelligent transportation system (ITS) has attracted growing attentions, but it also faces challenges, for example deep path loss and optical multi-path dispersion. In this work, we modelled an actual outdoor optical channel as a Rician channel and further proposed space-time block coding (STBC) orthogonal frequency-division multiplexing (OFDM) technology to reduce the influence of severe optical multi-path dispersion associated with such a mock channel for achieving the effective BER of 10^?6 even at a low signal-to-noise ratio (SNR). In this case, the optical signals transmission distance can be extended as long as possible. Through the simulation results of STBC-OFDM and single-input-single-output (SISO) counterparts in bit error rate (BER) performance comparison, we can distinctly observe that the VLC–ITS system using STBC-OFDM technique can obtain a strongly improved BER performance due to multi-path dispersion alleviation.     

MIMO-OFDM系统的空时编码技术及仿真分析

基于对窄带多输入多输出(Multiple Input Multiple Output,MIMO)技术和正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术的分析研究,发现二者具有相结合的可能性和现实性。通过建立二者结合的系统模型(MIMO-OFDM),给出该系统的空时编码方案。借助计算机仿真分析发现,结合后的MIMO-OFDM系统较传统的OFDM系统,可靠性获得提升。可见MIMO-OFDM系统的空时编码技术是一种提高通信质量的有效方法。     

STBC-OFDM系统中的协同分集研究

空时分组编码-正交频分复用(STBC-OFDM)系统是未来移动通信的研究热点。协同网络利用空间可获得的分布式天线,从而获得额外的空间分集增益。把协同分集应用到空时分组编码-正交频分复用系统中,给出一种新的协同空时块码OFDM系统。采用放大前传、译码前传和处理前传3种协同策略,研究在不同协同策略情况下的最大接收机机构和系统性能。     

Blind recognition of STBC-OFDM signals based on modified K-S test

Aiming at the problem that existed blind classification of STBC-OFDM in multiple input single output (MISO) communication system,an efficient method for blind classification of space-time block coded orthogonal frequency-division multiplexing (STBC-OFDM) signals based on modified Kolmogorov-Smirnov (K-S) test was proposed,when a single receiver antenna was employed at the receiver.Firstly,the model of received STBC-OFDM signals in MISO systems was given.Secondly,with the correlation of the coding matrix of STBC-OFDM signals,and the discrimination features function provided by the empirical cumulative distribution (CDFs) of the received OFDM blocks was constructed.Finally,the distance between CDFs was tested by the two-sample K-S test,which could blindly classify the STBC-OFDM signals.The proposed algorithm didn't need the estimation of channel,noise statistics and modulation type,and consequently,was well suited for non-cooperative communication context.Theoretical analysis and experimental verify its validity.     

基于LabVIEW的STBC-OFDM通信系统设计

结合LabVIEW所具有的图形化编程和交互式可控制界面的特点,采用层次化,模块化的设计方案,针对MIMO—OFDM系统进行模块化设计。在802．16d信道模型基础上,构建了一个典型的STBC—OFDM基带系统仿真模型与框架,并进行系统仿真和性能分析,给出了系统性能的基本仿真结论。该系统设计界面直观,数据流程清晰,并具有可扩展性,可用于对STBC—OFDM技术进行深入研究,同时为进一步优化系统算法打下了坚实基础。     

STBC-OFDM系统中有效降低计算量的盲接收机

为了降低空时分组码-正交频分复用（STBC-OFDM）系统中盲多用户接收机的计算复杂度,将基于子空间的接收机应用到STBC-OFDM系统中,证明其可以有效地降低计算复杂度并加快收敛速度。在此基础上,利用STBC码的正交特性推导出了两个权值之间的关系式,使得计算复杂度又降低了一半。仿真结果表明所提出的盲多用户接收机能剔除常规接收机中的冗余度,在误码率不变的前提下有效地解决了常规接收机中计算量大的问题。     

Resource optimization in distributed cooperative multi-relay system based on STBC-OFDM

On the basis of the amplify-and-forward relaying mode, a two-hop distributed cooperative multi-relay system is proposed combining with the space-time block coding OFDM (STBC-OFDM) technique. Taking the maximum end-to-end data rate as optimization criterion, the signal-to-noise ratio (SNR) of receiving terminal is deduced. On the basis of the water-filling theory, the optimal power allocation (OPA) is achieved for each subcarrier in each antenna and each relay node (RN) of the two-hop, to realize the resource optimization. Monte Carlo method is adopted in simulation. The simulation results show that compared with the uniform resource allocation scheme, the proposed OPA strategy can improve the system capacity. And the energy consumption of each transmission bit will be decreased, indicating the improvement of resource efficiency. In the scenario that the total power is limited, the system performance can be enhanced further by the distributed cooperative multi-relay through the diversity gain.