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.     

分布式发射天线V-BLAST信号的排序干扰抵消检测

针对V-BLAST信号通过分布的发射天线进入信道,该文提出了一种由于发射天线地域上的分布性引起的各发射天线发射信号不同时到达接收天线的V-BLAST排序干扰抵消(Order Interference Cancellation, OIC)检测算法。计算机仿真显示,该算法适用于任意个数的接收天线,在较高信噪比(20dB)的条件下,性能优于直接迫零算法3dB以上。在相同信噪比条件下,分布发射天线V-BLAST的排序干扰抵消检测算法比集中发射天线V-BLAST的排序干扰抵消检测算法有着更好的性能。     

BLAST系统的检测算法

作为一种能有效利用MIMO空间复用增益的传输结构,V-BLAST在近几年受到了广泛的关注,关于其检测算法的研究一直是MIMO研究的一个热点方向。阐述了经典的排序连续干扰抵消算法,并给出了关于检测分集增益的一个结论,该结论对于理解和设计BIAST检测算法都非常重要。论述了旨在改善OSIC性能的三种算法。对几种能有效减小OSIC复杂度的算法做了介绍,并对下一步的研究方向作了建议。     

采用改进ML-OSIC的MIMO联合检测

在垂直分层空时码(V-BLAST)多输入多输出(MIMO)系统中,最大似然检测算法(MLD)可以获得最佳的差错概率性能,但是其算法复杂度随着天线数目及其搜索空间数目呈指数增长;排序连续干扰消除(OSIC)算法具有高可行性的优点,但是其误码率由于无法防止误码扩散的原因而下降。基于OSIC算法复杂度主要来源于矩阵求逆运算,提出了一种改进的OSIC算法,该算法采用并行检测与精确检测值相结合的方案,在维持相对满意性能的情况下,减少算法复杂度。考虑到传统OSIC算法的误码扩散,将改进的OSIC算法与ML算法相结合,利用ML的穷尽搜索方式来提高算法的整体性能。为了避免ML算法给系统复杂度带来负担,通过一定的复杂度公式优先选出b层进行改进的OSIC算法,剩余的误差累积层使用MLD执行。仿真结果表明,所提算法复杂度小于传统OSIC算法,同时得到了接近ML算法的性能。     

V-BLAST系统中一种近似最佳列表检测算法

针对V-BLAST系统,提出一种近似最佳列表检测算法。该列表检测算法通过调节列表维数参数在检测性能和计算复杂度之间实现了较好的折衷。此外,给出了一种不同于OSIC算法的检测排序方法,进一步提高了检测性能。仿真和复杂度比较结果表明,在不相关和空间相关性较强的信道下,该列表检测算法均显著优于OSIC算法,甚至接近ML算法的性能,实现了性能和复杂度较好的折衷,是一种实用的选择。      

部分判决的OSIC:一种改进的VBLAST解码算法

VBLAST的传统译码算法:排序连续干扰抵消OSIC(Ordered Successive Interference-Cancellation),与最优译码算法:最大似然(Maximum Likelihood,ML)比较,虽然降低了复杂度,但其译码性能却相差较远。该文提出了一种改进的OSIC的译码算法:部分判决的排序干扰抵消算法(PartialDecision OSIC)。该算法在各层的判决中增加候选判决符号,并且在最后一层的判决中使用了最大似然检测,从而提高了译码的性能。从仿真结果可以看出,该算法比传统的VBLAST译码算法性能有较大的提高。     

部分正交空时块编码(POSTBC)及其解码算法

提出一种三发射天线的部分正交空时编码(POSTBC)结构.发送天线被分成两组,第一组采用Alamouti STBC编码,第二组则直接采用QPSK调制 .和Alamouti STBC 分组码相比它的优点是不需要偶数根发射天线. 由于各组发送的数据流相互独立,针对这一系统框架,采用了最优排序串行干扰消除(OSIC)译码算法和一种新的译码算法.计算机仿真结果表明,这种空时编码(MIMO)结构在等数据率的情况下能获得比相应的V-BLAST系统更优的性能.     

分布式MIMO系统中最优检测的简化算法

在V-BLAST结构的分布式MIMO系统中,针对发射天线地域上的分布性所引起的发射符号异步到达接收天线的问题,提出了一种接近最优检测性能简化算法。该算法首先遍历部分码元符号,且每次遍历时都使用分布式排序干扰抵消算法检测剩余符号,然后对得到的符号候选集进行搜索,恢复发送信号。莱斯衰落信道下的计算机仿真表明,该算法对接收端天线数目没有要求,且在获取接近最优检测性能的同时,有效地降低了计算复杂度。     

适用于两发射天线V-BLAST OFDM系统的排序插值QR分解算法

最近提出的插值QR分解算法有效降低了V-BLAST OFDM信号检测的复杂度。在大部分检测算法中,对信道矩阵按某策略排序后可进一步提高算法性能,但插值QR分解算法不能直接应用于这种情况。为解决这一问题,本文结合分组排序与插值QR分解的思路,通过引入不同列排序矩阵QR分解间的关系,提出一种适用于两发射天线的低复杂度排序插值QR算法。该算法可作为采用连续干扰抵消或球形译码算法的V-BLAST OFDM信号检测预处理方法。与对插值QR分解算法直接扩展的方法相比,该算法随着接收天线数的增多,复杂度节省程度更为明显,因此更适合基站接收机设计。     

针对大规模多输入多输出的动态调整排序串行干扰消除算法

针对多输入多输出（MIMO）系统非线性检测中排序串行干扰消除（OSIC）算法信号检测性能弱的问题,提出了一种可动态调整的OSIC(D-OSIC)检测算法。为解决早期的误差传播问题,通过最大似然（ML）算法选择最佳符号,提高ML-D-OSIC算法的检测性能。根据遍历容量动态调节消除层的数目,并结合混合迭代算法降低算法的复杂度。仿真结果表明,ML-D-OSIC算法的信号检测性能明显优于OSIC算法,检测性能可通过调整预定义阈值、偏移量和权重而提升,且复杂度远低于ML算法。     

Low complexity per-antenna rate and power control approach for closed-loop V-BLAST

Previous studies have shown that per-antenna rate and power control can greatly increase the data throughput of vertical Bell Labs layered space-time (V-BLAST), while an extra transmit antenna selection can provide additional diversity advantage. We combine the transmit antenna selection with power and rate control for each antenna. We derive a simple criterion for minimum bit-error rate (BER) or minimum total transmit power when the data throughput is constant over time. Zero-forcing and zero-forcing successive interference cancellation detections are considered. For practical implementation, we also present a fast algorithm that gives near-optimal performance with very low complexity. Simulation results show that the proposed closed-loop BLAST outperforms the open-loop V-BLAST significantly in terms of BER performance, especially when the antennas exhibit strong fading correlations.     

Spatial multiplexing with transmit antenna and constellation selection for correlated MIMO fading channels

We consider spatial multiplexing systems in correlated multiple-input multiple-output (MIMO) fading channels with equal power allocated to each transmit antenna. Under this constraint, the number and subset of transmit antennas together with the transmit symbol constellations are determined assuming knowledge of the channel correlation matrices. We first consider a fixed data rate system and vary the number of transmit antennas and constellation such that the minimum margin in the signal-to-noise ratio (SNR) is maximized for linear and Vertical Bell Laboratories Layered Space-Time (V-BLAST) receivers. We also derive transmit antenna and constellation selection criteria for a successive interference cancellation receiver (SCR) with a fixed detection order and a variable number of bits transmitted on each substream. Compared with a system using all available antennas, performance results show significant gains using a subset of transmit antennas, even for independent fading channels. Finally, we select a subset of transmit antennas to maximize data rate given a minimum SNR margin. A lower bound on the maximum outage data rate is derived. The maximum outage data rate of the SCR receiver is seen to be close to the outage channel capacity.     

V-BLAST系统中选择性最大比合并算法

通过选择性最大比合并(SC/MRC)算法,在并行干扰抵消(PIC)技术的基础上,对V-BLAST系统各接收天线的干扰抵消结果按照SC/MRC合并,实现了分集接收.该算法最多可以实现与接收天线数等同的分集增益,而通过选择信道条件较好的几个接收天线进行合并,可以在性能与复杂度之间取得折衷.MRC合并只需与选择合并的天线数线...     

Fuzzy adaptive partial parallel multistage detection for MIMO systems

Vertical Bell Laboratories Layered Space-Time (V-BLAST) detection followed by a full parallel interference cancellation (full PIC) or a constant-weight partial parallel interference cancellation (CW-PPIC) scheme has been proposed. However, its performance degrades when the received power of the antenna is unbalanced and/or the system is heavily loaded. Therefore, V-BLAST is proposed, followed by fuzzy adaptive partial parallel multistage detection for MIMO systems. The simulation results show that the error probability of this proposed method is better than that of V-BLAST followed by full PIC or CW-PPIC schemes     

Interference Mitigation in MIMO Systems by Subset Antenna Transmission

This paper investigates subset antenna transmission (SAT) for multiple-input multiple-output (MIMO) systems in the presence of strong dominant co-channel interferer. The capacity gain from SAT is investigated in the context of optimal antenna subset selection and power allocation. The SAT does not require channel state information of the co-channel interference, and achieves capacity gains by distributing the transmit power equally over a selected subset of the transmit antennas. The capacity gain of the SAT method is analyzed in terms of transmit power and eigenvalues of channel matrix, and its performance in V-BLAST MIMO systems with various signal constellations is evaluated by computer simulation.     

GMD V-BLAST系统天线选择

基于最大容量和最小差错率准则,研究了在GMD V-BLAST系统中的天线选择问题。选用以信道矩阵非零奇异值的几何均值最大化为目标函数,可以避免容量与差错率性能之间的矛盾。在所有可用天线中进行选择的全搜索算法虽有最佳性能,但复杂度太高。基于贪婪算法,对发射天线采用快速的逐增选择策略,对接收天线采用快速的逐减选择策略,可以显著降低计算的复杂性。计算机仿真结果表明,所采用的快速天线选择算法可以较低的复杂度获得接近全搜索法的容量和分集增益。     

Transmit-antenna selection for spatial multiplexing with ordered successive interference cancellation

This letter proposes a low-complexity algorithm for transmit-antenna selection in a multi-input multi-output spatial multiplexing system with per-antenna rate control and an ordered successive interference cancellation receiver. The active antenna subset and its transmission rate are determined at the receiver, and conveyed to the transmitter using limited feedback. We propose a serial antenna-selection procedure consisting of a successive process that tests whether transmit-antenna selection gain exists when the antenna with the lowest signal-to-interference-plus-noise ratio (SINR) is discarded at each selection stage. Furthermore, we show that "reverse-detection ordering", whereby the signal with the lowest SINR is decoded at each stage of successive decoding, widens the disparities among fractions of the whole capacity allocated to each individual antenna, and thus maximizes a gain of antenna selection. Numerical results show that the proposed reverse-detection-ordering-based serial antenna selection induces a negligible capacity loss, compared with the exhaustive selection strategy, even with considerably reduced complexity.     

Iterative QR Detection for BLAST

We study an iterative detection algorithm of an uncoded multi-transmittermulti-receiver system. The main data stream is demultiplexed into Msubstreams, and each substream is modulated independently then transmitted byits dedicated antenna. The receiver disposes of N M antennas. Over eachreceive antenna the signal is a superposition of the M substreams affected byindependent fades and disturbed by AWGN. The detection algorithm is based onthe QR decomposition of the channel transfer matrix which is then used toperform hard or soft inter-substream interference cancellation. Comparisonsare done with the V-BLAST optimal order (OPT) detection algorithm. Theproposed algorithm is 4 to 8 times less complex than that of the V-BLAST OPT,while maintaining comparable performance.     

线性离散码系统中基于近似容量分析的发送天线选择算法

为了降低应用线性离散码(LDC)的多输入多输出系统中发送天线选择算法的复杂度,该文利用LDC的线性变换矩阵的酉矩阵参数化性质,推导出了一种考虑LDC矩阵平均影响的近似容量表达式。近似容量表达式不涉及时间扩展的高阶等效信道矩阵的运算,从而基于近似容量的发送天线选择算法可以有效地降低运算复杂度。该文从近似容量出发,给出了最大化近似容量的发送天线选择算法和基于矩阵消元的天线选择算法。近似容量表达式为基于垂直空时分层码(V-BLAST)提出的低复杂度天线选择算法在LDC系统中的直接应用提供了理论支持。仿真结果表明,所提方案具有与最优天线选择算法相近的性能,但具有更低的计算复杂度。基于矩阵消元的天线选择算法与在V-BLAST系统中提出的基于范数和相关性的天线选择算法相比,可以获得更好的分集增益,因而具有更好的误码率性能。     

Group transmit antenna selection based on GIS technology for V-BLAST system

The conventional transmit antenna selection for Vertical Bell Laboratories Layered Space Time （V-BLAST） system is very complex because it needs to compute the inverse of channel matrices time after time. In this paper, a new group transmit antenna selection scheme for V-BLAST system is proposed. The 1st group transmit antennas are decided according to a certain selection criterion among the available antennas. Then, with Group Interference Suppression （GIS） technology, the interferences of the transmit symbols from the selected antennas can be suppressed. Finally, the 2nd group transmit antennas are decided among the residual available antennas. Simulations show that its performance is lower than that of the conventional selection scheme. However, the new selection scheme has lower complexity than the conventional one.