MIMO-OFDM系统原理及其关键技术

介绍了第四代移动通信系统中的MIMO-OFDM技术,阐述了OFDM、MIMO技术及MIMO-OFDM系统的基本原理与特点,并介绍了MIMO空时信号处理技术、MIMO OFDM同步、信道估计、信道编码以及自适应技术.     

MIMO-OFDM系统的盲信道估计算法综述

 本文首先介绍了MIMO-OFDM系统模型,然后讨论了研究MIMO-OFDM移动通信系统信道估计的意义.紧接着对MIMO-OFDM系统目前存在的几种典型盲信道估计算法进行分析和讨论.最后总结和展望了MIMO-OFDM系统信道估计算法的研究方向和关键问题.     

MIMO-OFDM系统中的空时编码技术研究

近年来,宽带无线通信技术和应用得到了迅猛的发展.人们对无线数据和多媒体业务的需求,促进了用于高速宽带无线通信的诸多新技术的发展和应用.其中,MIMO技术利用多径效应,能够极大改善无线通信的频谱效率和通信可靠性.OFDM技术具有优越的频谱效率,两者的结合即MIMO-OFDM技术被认为是未来移动通信系统的关键技术.本文简要介绍MIMO技术和OFDM的基本原理,MIMO-OFDM系统以及空时编码技术在MIMO-OFDM系统中的应用.     

移动通信中MIMO-OFDM技术概述

采用MIMO技术的OFDM系统是现代移动通信的核心技术。本文首先介绍正交频分复用(OFDM)技术和多输入多输出(MIMO)系统的基本原理,简述MIMO-OFDM技术及其特点,并初步探讨MIMO-OFDM系统的关键技术。     

MIMO-OFDM系统中的空时编码技术

MIMO与OFDM技术相结合成为4G宽带移动通信的核心技术。全面介绍了MIMO-OFDM技术及其特点,分析了3种空时编码技术,探讨了空时编码技术在MIMO-OFDM系统中的应用,并展望了其发展前景。     

4G移动通信中的OFDM—MIMO技术研究

介绍了4G移动通信中的OFDM技术、MIMO技术的基本原理及MIMO-OFDM系统的关键技术包括信道估计、同步、分集技术和空时编码技术。MIMO技术与OFDM技术结合，成为4G移动通信中有效对抗频率选择性衰落、提高数据传输速率、增大系统容量的关键技术，是第四代移动通信系统研究的热点问题。     

4G通信中MIMOOFDM技术的应用研究

随着社会的快速发展,移动通信技术的应用越来越重要,本文主要介绍了第四代移动通信技术所面临的问题,MIMOOFDM技术的原理和优势以及MIMO-OFDM技术在4G系统中应用的必要性。     

MIMO-OFDM系统中信号检测算法的研究

MIMO和OFDM技术是未来宽带无线移动通信系统中关键的核心技术,在MIMO-OFDM无线通信系统中,接收端在检测信号时采用的检测算法对提高整个系统的性能至关重要.对目前MIMO-OFDM无线通信系统中最主要的3类信号检测算法一最优检测算法、传统的线性检测算法和次优的检测算法进行了对比分析介绍,得出在性能上逼近最优检测...     

基于导频信号的MIMO-OFDM同步技术

MIMO-OFDM技术将成为第4代移动通信系统的关键技术,因MIMO-OFDM对时间和频率偏移非常敏感,因此MIMO-OFDM同步显得尤为重要。提出了一种新的MIMO-OFDM定时同步和频偏同步技术。以GCL序列为基础设计了一个新的符合MIMO-OFDM同步技术的导频序列,通过对该导频序列进行2次相关得到频率估计,并将所得频率运用到定时同步中,得到更为准确的时间估计。仿真结果表明,在相同的信噪比情况下,该方法可以使得系统的误码率和帧传送误码率相对传统方法得到进一步减小。     

LTE中MIMO-OFDM的符号同步算法

未来的移动通信系统LTE的下行链路将广泛采用MIMO-OFDM技术。基于MIMO-OFDM系统的表达式和信道模型,以及Zadoff-Chu序列,提出了一种等周期的伪叠加Zadoff-Chu序列的集中式和分布式MIMO同步算法,并进行了仿真。仿真结果表明该算法能够准确地进行符号时间同步,验证了所提出符号同步算法的有效性。     

新一代移动通信的核心技术OFDM调制技术

作为4G中的关键技术,正交频分复用(OFDM)把信道分成许多正交子信道,各子信道之间保持正交,频谱相互重叠,这样减少了子信道间干扰,提高了频谱利用率。对OFDM系统的实现进行了研究设计,给出了一个基于FFT算法的系统实现方案,介绍了作为4G关键技术的OFDM调制技术的发展状况,阐述了其基本原理及两个关键问题同步问题和PAPR问题的解决方法。     

TDD-CDMA for the 4th generation of wireless communications

This article discusses an evolutionary TDD mode of CDMA-based path for 3.5G/4G systems. This technology has already been the basis of two 3G standards: TD-CDMA and TD-SCDMA with a synchronous uplink. Several techniques have been developed that allow TDD-CDMA-based systems to transmit at rates usually associated with 3.5G to 4G, up to 10-20 Mbit/s with wide area coverage. The present TDD-CDMA-based 3G standards are evolving to provide these higher rates, while fully retaining the coverage and mobility associated with, and expected from, the present mobile communications systems. This article discusses how TDD-CDMA specific techniques facilitate delivering services at data rates associated with 3.5G and 4G. We review how TDD-CDMA can provide for asymmetric uplink and downlink transmissions, facilitate deployment of advanced antennas for improved downlink coverage, and enable provision of advanced receiver techniques in base stations and mobiles. We also discuss how these techniques affect systems capacity in full packet-switched IP-based systems. We then discuss 4G TDD CDMA systems: those with different modulation techniques for uplink and downlink communications. These are generally based on a multicarrier mode of CDMA, and may incorporate OFDM technique.     

OFDM关键技术及应用

与传统单载波技术相比,正交频分复用（OFDM）技术具有频谱利用率高和抗频率选择性衰落能力强等优点,是提高系统传输速率和可靠性的有效手段,并且随着对OFDM技术的研究逐渐完善和成熟,OFDM技术已经得到广泛应用。在此主要介绍了OFDM技术原理和关键技术,分析了OFDM技术的应用现状,展望了在下一代移动通信中的应用和研究方向。     

Large scale P/G grid transient simulation using hierarchical relaxed approach

This paper proposes a hierarchical relaxed approach to analyze large scale on-chip power/ground (P/G) grids with C4 packages efficiently. Different from the existing hierarchical approach where macro models and time-consuming matrix density reduction technique are used, this novel approach uses an iterative relaxation procedure to explicitly exploit the character of boundary nodes caused by C4 bumps, which can lead to more speedup without losing any accuracy. Also, an efficient partition strategy is generated to help the new algorithm to achieve higher performance on C4 based P/G grid. Experimental results demonstrate that the new algorithm is as accurate as the existing hierarchical method while it delivers more speedup over it for C4 based P/G grid.     

地铁公网泄漏电缆四缆接入方案

随着5G技术的发展,地铁中公网通信也需要考虑5G覆盖,地铁公网通信是采用泄漏电缆来实现的,相应的泄漏电缆数量也要是4根.本文对三大运营商进入地铁的十几个系统进行了互调干扰分析,给出了各系统在4根漏缆中分配的建议.     

An Efficient Implementation and Analysis of Tail-Biting Convolution Coding Algorithm for OFDM Based System in Terms of Speed,Memory and Peak-to-Average Power Ratio Using DSP

Wireless Personal Communications - Fourth Generation (4G) mobile communication system uses Orthogonal Frequency Division Multiplexing (OFDM). With this technique, high data rate demands are...     

Classification of DoS Attacks in Smart Underwater Wireless Sensor Network

As per the most recent literature, Orthogonal Frequency Division Multiplexing (OFDM), a multi access technique, is considered most suitable for the 3G, 4G and 5G techniques in high speed wireless communication. What made OFDM most popular is its ability to deliver high bandwidth efficiency and superior data rate. Besides it, high value of peak to average power ratio (PAPR) and Inter Carrier Interference (ICI) are the challenges to tackle down via appropriate mitigation scheme. As a research contribution in the present work, an improved self-cancellation (SC) technique is designed and simulated through Simulink to mitigate the effect of ICI. This novel proposed technique (Improved SC) is designed over discrete wavelet transform (DWT) based OFDM and compared with conventional SC scheme over different channel conditions i.e. AWGN and Rayleigh fading environments. It is found that proposed DWT-OFDM with Improved SC scheme outperforms conventional SC technique significantly, under both AWGN and Rayleigh channel conditions. Further, in order to justify the novelty in the research contribution, a Split-DWT based Simulink model for Improved SC scheme is investigated to analyse the BER performance. This Split-DWT based Simulink model presented here foretells the future research potential in wavelet hybridization of OFDM to side-line ICI effects more efficiently.

     

机载高分辨力SAR实时运动补偿的实现

本文详细地分析了载机运动误差与回波相位的关系,提出了基于G4DSP信号处理板的机载SAR实时运动补偿方法,该方法利用G4DSP的四个CPU构成流水线处理器,采用子孔径方法分段提取回波的多普勒调频斜率,然后利用调频斜率的变化计算载机的运动误差,通过相位误差函数与方位数据的时域相乘补偿运动误差。实时信号处理机的实验表明,本文方法能实时和有效的实现机载SAR运动补偿,获得满意的成像质量。     

SER bound for ordered ZF-SIC receiver in M-QAM MIMO system

With the advances of the 4th generation(4G) mobile communications targeting multi-user QoS-guaranteed multimedia services,multiple input multiple output(MIMO) combined with multi-level quadrature amplitude modulation(M-QAM) technique gains great popularity for its capability of supporting high data rate.In this article,the statistical distribution of signal to noise plus interference ratio(SINR) in each recursive step of optimal ordered zero-forcing perfect successive interference cancellation(ZF-OOPSIC) de...