MIMO SC-FDMA定时同步的并行干扰消除算法

针对LTE-Advanced上行链路MIMO SC-FDMA系统中定时同步问题,提出一种基于QR分解与并行干扰消除PIC相结合的定时同步算法。该算法通过QR分解检测获得初步的信息估计值,应用并行干扰消除方法,将定时偏移所产生的干扰从接收信号中消除。理论分析与仿真结果表明,该算法可显著提高系统性能。     

V-BLAST MIMO系统中基于增广信道矩阵分析的发射天线选择算法

为了减少MIMO无线通信系统的射频链路硬件成本和降低系统复杂度,针对采用排序逐次干扰抵消(OSIC)接收的MMSE V-BLAST系统,通过对增广信道矩阵进行次优排序和QR分解分析,提出了一种新颖低复杂度的发射天线选择算法.与其它方案不同的是,本文算法综合考虑了排序、干扰抵消和噪声对天线选择性能的影响.仿真结果表明,该算法的性能比其它算法的性能有很大改善.     

An Ordered Successive Interference Cancellation Scheme in UWB MIMO Systems

In this letter, an ordered successive interference cancellation (OSIC) scheme is applied for multiple‐input multiple‐output (MIMO) detection in ultra‐wideband (UWB) communication systems. The error rate expression of an OSIC receiver on a log‐normal multipath fading channel is theoretically derived in a closed form solution. Its bit error rate performance is analytically compared with that of a zero forcing receiver in the UWB MIMO detection scheme followed by RAKE combining.     

Closed-loop Grouped Space–Time Block Code: Encoding,Decoding and Codeword Selection

A design of closed-loop grouped space–time block codes (G-STBCs) including encoding, decoding and codeword selection is proposed for the downlink over Rayleigh flat-fading channels. In particular, at the transmitter, the antenna array is partitioned into a number of groups, each of which is encoded based on the orthogonal STBC (O-STBC). At the receiver, by exploiting the algebraic structure of orthogonal codes, a low-complexity, in recursion form, group-wise ordered successive interference cancellation (OSIC) detector is developed. Moreover, the G-STBC codeword is designed and a G-STBC codeword selection criterion that minimizes the BER performance under the constraints of a fixed spectral efficiency and total transmit power is then proposed. The selection index of the G-STBC codeword and the associated modulation type are determined at the receiver and conveyed to the transmitter with a limited feedback overhead to choose an appropriate mode for transmission. Finally, Numerical examples are used for illustrating the performance of the proposed G-STBCs, OSIC based detection and G-STBC codeword selection criterion.

基于分组的ML-SIC的MIMO联合检测算法

在MIMO检测算法中,串行干扰抵消算法(SIC)会引起误差传递.针对这一问题提出分组检测,结合最优检测算法最大似然检测(ML)保证前面层检测出信号的准确性,减小误差传递.仿真结果表明,ML-SIC的联合检测算法能有效减少误差传递,增加系统整体性能.     

V-BLAST系统接收端解码算法的改进

本文在总结了V—BLAST系统的接收端算法基础上,着重对最大似然（ML）和串行干扰抵消（OSIC）相结合的算法进行讨论和仿真。结果表明,对n层符号,选取其中I层采用ML算法,剩下的n-1层采用OSIC算法,不会大幅增加原OSIC算法复杂度,且误码率性能大幅提高。同时指出,基于OSIC思想,对瞬时信噪比（SNR）最大的符号采用ML算法,余下的符号采用OSIC算法解码,可以逼近ML算法的性能。     

联合ML和OSIC的VBLAST解码算法

使用多个发射天线和多个接收天线可以获得巨大的通信容量。作为MIMO系统的一种实现方案，VBLAST可以获得很高的频谱利用率。传统的VBLAST译码算法OSIC(Ordered Successive Interference Cancellation)在其译码性能上和最大似然ML(Maximum Likelihood)译码差距较大，而ML，的复杂度是随着发射天线数呈指数增加的。因此，本文针对VBLAST的译码，折中考虑VBLAST的解码复杂度和解码性能，提出了联合ML，和OSIC的两种改进的VBLAST解码算法：ML_OSIC和OSIC_ML。当选取用ML译码的符号数适中时，可以在远低于ML的复杂度基础上获得远好于OSIC的译码性能。     

基于OSIC的MIMO SC-FDMA系统载波同步算法

针对MIMO SC-FDMA系统载波频率偏移敏感问题,提出一种基于OSIC的载波同步算法.该算法对存在载波频偏(CFO)的信号进行排序、零化、迭代均衡实现干扰消除.理论分析和仿真实验表明该算法实现了载波频偏干扰消除的目的,并且提高了系统性能.     

基于串行干扰消除的V—BLAST检测

贝尔实验室分层空时结构（BLAST）是实现多输入多输出（MIMO）无线通信系统空时复用并获得容量增益的一种重要技术．本文将以垂直BLAST（V-BLAST）为主要对象,综述基于串行干扰消除的V-BLAST检测算法及相应的复杂度和误码性能,并对其发展作了有关展望。     

准正交空时编码的MMSE检测

多天线系统中发射端采用准正交空时编码(QOSTC)时,与正交空时编码(OSTC)相比,虽然前者可达到全速率传输,但接收端须采用比较复杂的最大似然(ML)检测.本文提出QOSTC的MMSE检测方法,不需要作矩阵求逆运算,因而比BLAST系统的MMSE检测简单,仿真结果表明该检测方法性能及复杂度介于ZF检测和ML检测之间.     

基于后验概率估计的软输出MMSE MIMO排序串行干扰抵消检测算法

该文研究了信道编码无线MIMO通信系统中的软输出MMSE排序串行干扰抵消检测算法。利用MMSE滤波器输出的高斯近似表示,提出了基于后验概率估计的判决误差传播抑制算法,以提高检测算法输出的编码比特对数似然比的可靠性;利用检测器的矩阵结构和矩阵求逆引理,进一步提出了降低复杂度的实现方法。仿真结果表明:提出的检测算法优于现有算法,当BER为10-4,在所给的仿真条件下有1～3dB的性能增益。     

MIMO下行链路联合波束成形稳健性设计

针对MIMO下行链路中的发射/接收波束成行器,提出了一种对非精确CSI稳健的联合设计方案。方案采用的设计准则是在总发射功率受限的条件下最小化系统和MSE。根据此非凸和非线性优化问题的最优解条件,通过交替地计算每个用户的最优解来近似地获得原问题最优解。仿真结果表明,与非稳健性方法相比,该方案能有效地减少非精确CSI引起的性能损失。     

Low-complexity adaptive decision-feedback equalization of MIMO channels

A new adaptive MIMO channel equalizer is proposed based on adaptive generalized decision-feedback equalization and ordered-successive interference cancellation. The proposed equalizer comprises equal-length subequalizers, enabling any adaptive filtering algorithm to be employed for coefficient updates. A recently proposed computationally efficient recursive least squares algorithm based on dichotomous coordinate descents is utilized to solve the normal equations associated with the adaptation of the new equalizer. Convergence of the proposed algorithm is examined analytically and simulations show that the proposed equalizer is superior to the previously proposed adaptive MIMO channel equalizers by providing both enhanced bit error rate performance and reduced computational complexity. Furthermore, the proposed algorithm exhibits stable numerical behavior and can deliver a trade-off between performance and complexity.     

基于空间交替广义最大似然的低复杂度列表检测

针对V-BLAST系统,提出了一种低复杂度的空间交替广义最大似然（SAGL）列表检测算法。该算法的子检测器由简化最大似然（SML）检测器和连续干扰抵消（SIC）检测器组成。传统SIC算法每次只能对单一符号进行检测,而所提算法则利用相邻符号进行联合滑动检测,可以获得更高的分集增益。此外,所提SAGL算法对检测结果进行迭代修正来进一步提升检测性能。分析与仿真结果表明,与传统列表检测算法相比,所提SAGL列表检测算法以少许复杂度的增加为代价显著提升了检测性能。     

LTE系统中的信号检测算法性能分析

为了满足高数据率和高系统容量的需求,LTE系统采用了MIMO多天线技术.MIMO信号检测算法的性能将直接影响系统的整体性能.本文主要介绍了LTE系统中的ZF、MMSE、OSIC和Turbo迭代检测算法,并通过LTE下行链路仿真对其进行性能分析.结果表明Turbo迭代检测性能最优,并选择2次迭代即可.MMSE-OSIC、MMSE、ZF-OSIC性能次之,ZF性能最差.