Capacity of distributed antenna network by using single‐carrier frequency domain adaptive antenna array

Single‐carrier frequency domain adaptive antenna array (SC‐FDAAA) has been proposed and proved in our previous study to be effective in suppressing multiple access interference in a severely frequency selective fading channel. In this paper, we studied the performance of SC‐FDAAA in a distributed antenna network (DAN). To make it clear whether the performance of SC‐FDAAA can benefit from the distributed nature of DAN or not, we made a comparison between DAN and the traditional cellular network, that is, central antenna network. The bit error rate distribution and the system capacity (both link capacity and cellular link capacity) are presented. It is shown that by using the SC‐FDAAA, cellular link capacity is maximized by using single frequency reuse. In addition, the capacity of SC‐FDAAA can also benefit from the distributed nature of DAN. Copyright © 2012 John Wiley & Sons, Ltd.     

A Comparison of Frequency-Domain Block MIMO Transmission Systems

Block transmission techniques, with appropriate cyclic prefix and frequency-domain processing schemes, have been shown to be excellent candidates for digital transmission over severely time-dispersive channels, allowing good performance with implementation complexity that is much lower than traditional time-domain processing schemes. Orthogonal frequency-division multiplexing (OFDM) modulation is the most popular block transmission technique. Single-carrier (SC) modulation using frequency-domain equalization (FDE) is an attractive alternative approach based on this principle. In this paper, we propose two new receiver structures for multiple-input-multiple-output (MIMO) channels employing SC (MIMO-SC) modulation and FDE schemes. These receivers have a hybrid structure with frequency-domain feedforward and time-domain feedback filters for intersymbol interference (ISI) and interference cancellation. The proposed schemes are compared with different MIMO systems employing OFDM modulation (MIMO-OFDM) receivers in terms of performance [bit error rate (BER) and throughput] and complexity. Our performance results show the superiority of MIMO-SC approaches relative to MIMO-OFDM in terms of the BER performance for the simulated scenarios. Also, the simulation results show that the proposed hybrid MIMO-SC receivers yield a higher throughput than a MIMO-OFDM system.     

Analysis of MIMO MRT/SC Systems

Multiple-input multiple-output (MIMO) diversity systems with maximum ratio transmission at the transmitter and selection combining at the receiver (MRT/SC) are presented to obtain the tradeoff between the system performance and receiver complexity. Closed-form expressions for average symbol error rate (SER) in single-user scenario and average capacity in multi-user scenario are derived to get the performance of MIMO MRT/SC systems under independent and identically distributed (i.i.d.) Rayleigh fading. Our study shows that performance of MIMO MRT/SC systems outperforms that of MIMO space-time block coding systems. The analytical results are compared with the simulation results and a good agreement is obtained.     

Multiuser MIMO receivers for space frequency block coded SC‐FDMA systems

Single carrier‐frequency division multiple access (SC‐FDMA) has been adopted as the uplink transmission standard in fourth generation cellular network to enable the power efficiency transmission in mobile station. Because multiuser MIMO (MU‐MIMO) is a promising technology to fully exploit the channel capacity in mobile radio network, this paper investigates the uplink transmission of SC‐FDMA systems with orthogonal space frequency block codes (SFBC). Two linear MU‐MIMO receivers, orthogonal SFBC (OSFBC) and minimum mean square error (MMSE), are derived for the scenarios with limited number of users or adequate receive antennas at base station. In order to effectively eliminate the multiple access interference (MAI) and fully exploit the capacity of MU‐MIMO channel, we propose a turbo MU‐MIMO receiver, which iteratively utilizes the soft information from maximum a posteriori decoder to cancel the MAI. By the simulation results in several typical MIMO channels, we find that the proposed MMSE MU‐MIMO receiver outperforms the OSFBC receiver over 1 dB at the cost of higher complexity. However, the proposed turbo MU‐MIMO receivers can effectively cancel the MAI under overloaded channel conditions and really achieve the capacity of MU‐MIMO channel. Copyright © 2014 John Wiley & Sons, Ltd.     

WLAN中的MIMO OFDM技术

文章介绍了多输入多输出(MIMO)与正交频分复用(0FDM)技术以及他们各自的特点。给出了在无线局域网中应用的MIMO OFDM技术的实现方案，探讨了实现MIMO OFDM技术的关键，并展望了MIMO OFDM技术的发展前景。     

下一代无线通信关键技术及其在遥测中的应用

围绕下一代无线通信中正交频分复用(OFDM)、带频域均衡的单载波(SC/FDE)与多输入多输出(MIMO)技术,首先综述了这些技术的工作原理、发展历程以及关键问题,重点对OFDM的研究热点进行了分析。接下来探讨了这几项技术在遥测领域的应用。最后得出结论,认为:OFDM在航空遥测有着广泛的应用前景;MIMO在很多遥测领域的应用都有很大潜力;单载波频域均衡(SC-FDE)技术可以适应发射功率受限,多径干扰严重的环境,在航空遥测与导弹遥测中是一种新的鲁棒的遥测体制。     

D-MIMO技术及应用策略研究

分布式MIMO（D-MIMO）是一种解决未来超密集组网高干扰问题的技术方案,通过将干扰源转变为有用信号源,降低重叠覆盖区域干扰,提高用户体验,有利构建无边界用户体验的网络。本文对D-MIMO进行了基本原理及关键技术分析,对该技术的性能增益进行了仿真与外场测试研究.同时,结合技术优势与劣势、投资、现网需求分析,提出了该技术的规划应用思路与建议。     

A simplified QRD-<Emphasis Type="Italic">M</Emphasis> signal detection algorithm for MIMO-OFDM systems

QR Decompositon with an M-algorithm (QRD-M) has good performance with low complexity, which is considered as a promising technique in Multiple-Input Multiple-Output (MIMO) detections. This paper presented a simplified QRD-M algorithm for MIMO Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems. In the proposed scheme, each surviving path is expanded only to partial branches in order to carry out a limited tree search. The nodes are expanded on demand and sorted in a distributed manner, based on the novel expansion scheme which can pre-determine the children’s ascending order by their local distances. Consequently, the proposed scheme can significantly decrease the complexity compared with conventional QRD-M algorithm. Hence, it is especially attractive to VLSI implementation of the high-throughput MIMO-OFDM systems. Simulation results prove that the proposed scheme can achieve a performance very close to the conventional QRD-M algorithm.     

基于干扰温度的多用户MIMO频谱共享系统容量分析

在无线通信认知无线电中,频谱共享系统被证实能够提供更高的频谱利用率。考虑到多用户多天线的频谱共享系统中次用户的发射功率受限于主用户的干扰温度,介绍了单天线系统和3种不同MIMO传输机制,并根据SNR分别推导出具体的容量表达式。最后通过仿真得出ST/SC方式能够获得最佳容量,而STBC方式应用于频谱共享系统没有提升容量的优势。     

Per-tone equalization for MIMO OFDM systems

This paper focuses on multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems with channel order larger than the cyclic prefix (CP) length. Writing the demodulating fast Fourier transform (FFT) as a sliding FFT followed by a downsampling operation, we show in this paper that by swapping the filtering operations of the MIMO channel and the sliding FFT, the data model for the temporally smoothened received signal of each individual tone of the MIMO OFDM system is very similar to the data model for the temporally smoothened received signal of a MIMO single-carrier (SC) system. As a result, to recover the data symbol vectors, the conventional equalization approach for MIMO SC systems can be applied to each individual tone of the MIMO OFDM system. This so-called per-tone equalization (PTEQ) approach for MIMO OFDM systems is an attractive alternative to the recently developed time-domain equalization (TEQ) approach for MIMO OFDM systems. In the second part of this paper, we focus on direct per-tone equalizer design and adapt an existing semi-blind equalizer design method for space-time block coding (STBC) SC systems to the corresponding semi-blind per-tone equalizer design method for STBC OFDM systems.     

On Issues about the Application of MIMO in Mobile Cellular Communications

1　Introduction　Thenewgeneration (beyond 3G/4G)mobilecel lularcommunicationsystemneedstosatisfythehighcapacitydemandsdrivenbysomeapplicationssuchasInternetandmultimediaapplications.Insuchasystem ,thekeytoachievetherequiredratesinahighlylimitedradiospectrumresourceisinadoptionofnoveltransmissiontechniques,whichofferhighspectralefficiencyandhightransmissionreliabilityrelativetothecurrentsystems.Multiple InputMul tiple Output(MIMO)systemusingmultipleantennasattransmitandreceiveendcanincrease…     

分布式天波超视距雷达体制研究

论述了天波超视距雷达及多输入多输出体制近年来的发展和研究状况.同时,从分布式天波超视距雷达所面临的任务需求和技术体制等方面展开分析,给出了雷达系统架构以及2种配置方式,并就其资源配置和信息融合进行了设计.最后,根据技术难点和成熟度提出了分布式天波超视距雷达"三步走"的技术发展路线及相应的阶段目标,对其中的关键技术还进行了评述.     

An Efficient Cyclic Prefix Reconstruction Technique for MIMO Single-Carrier Frequency-Domain Equalization

In this letter, an efficient cyclic prefix reconstruction (CPR) technique with turbo equalization is developed for a multi-input multi-output (MIMO) single-carrier frequency-domain equalization (SC-FDE) system. The proposed method consists of pre-processing estimation (PPE) and residual inter-carrier interference suppression (RICIS). The PPE is employed to compute initial values of MIMO turbo equalization, and the RICIS is used to mitigate residual intercarrier interference (ICI) after each iteration of the CPR. By applying the proposed method to MIMO SC-FDE system with insufficient cyclic prefix (CP), we can significantly improve its error performance, obtaining both the benefits of multiplexing gain and spectral efficiency gain     

Dynamic resource allocation with beamforming for MIMO OFDM systems: performance and effects of imperfect CSI

We propose three different dynamic resource allocation algorithms using adaptive beamforming for multiple-input multiple-output (MIMO) OFDM systems, and investigate their performance over multipath fading channels under perfect and imperfect channel state information (CSI). These approaches involve the use of adaptive modulation, adaptive frequency-domain power allocation, and/or adaptive sub-channel allocation. By employing the proposed approaches in MIMO/OFDM systems, significant performance improvement can be achieved compared to the conventional adaptive antenna array based OFDM. The investigation of the effects of imperfect CSI reveals that the adaptive-modulation based approach is too sensitive to channel estimation errors, and that its performance is worse than the adaptive frequency-domain power allocation and/or adaptive sub-channel allocation approaches. The performance analysis also shows that combining adaptive power allocation with sub-channel allocation yields the best performance under imperfect CSI while being robust to channel estimation errors.     

Energy efficiency comparison between distributed and co‐located MIMO systems

Energy efficiency (EE) is becoming more and more important in future wireless communications because of limited battery power in mobile terminals. In this paper, we compare EE of the distributed MIMO (D‐MIMO) and co‐located MIMO (C‐MIMO) in uplink systems. Taking into account both circuit and transmit power, we derive an analytical expression for EE of D‐MIMO and C‐MIMO systems in a composite Rayleigh‐lognormal channel. What is more, an optimization algorithm is proposed to get the optimal EE values while satisfying given spectral efficiency requirement for both D‐MIMO and C‐MIMO systems. Simulation results show that D‐MIMO systems are more energy effective than C‐MIMO systems when considering the realistic systems, and the optimal EE can be obtained by the proposed algorithm while satisfying given spectral efficiency requirement. Copyright © 2012 John Wiley & Sons, Ltd.     

Characterizing the capacity gain of stream control scheduling in MIMO wireless mesh networks

Stream control (SC) has recently attracted attentions in the research of multiple input multiple output (MIMO) wireless networks as a potential way to improve network capacity. However, inappropriate use of SC may significantly degrade network capacity as well. In this paper, we provide the first formal study on SC scheduling in MIMO wireless mesh networks (WMNs). We derive the theoretical upper bound on network capacity gain of SC scheduling. We also provide an efficient scheduling algorithm and show that its achieved network capacity gain is close to its theoretical upper bound. Moreover, we point out the poor performance of a previous SC scheduling algorithm SCMA under the general settings of WMNs. This formal characterization provides a deeper understanding of steam control scheduling in MIMO WMNs. Copyright © 2008 John Wiley & Sons, Ltd.     

Independent component analysis for multiple-input multiple-output wireless communication systems

Independent component analysis (ICA), an efficient higher order statistics (HOS) based blind source separation technique, has been successfully applied in various fields. In this paper, we provide an overview of the applications of ICA in multiple-input multiple-output (MIMO) wireless communication systems, and introduce some of the important issues surrounding them. First, we present an ICA based blind equalization scheme for MIMO orthogonal frequency division multiplexing (OFDM) systems, with linear precoding for ambiguity elimination. Second, we discuss three peak-to-average power ratio (PAPR) reduction schemes, which do not introduce any spectral overhead. Third, we investigate the application of ICA to blind compensation for inphase/quadrature (I/Q) imbalance in MIMO OFDM systems. Finally, we present an ICA based semi-blind layer space-frequency equalization (LSFE) structure for single-carrier (SC) MIMO systems. Simulation results show that the ICA based equalization approach provides a much better performance than the subspace method, with significant PAPR reduction. The ICA based I/Q compensation approach outperforms not only the previous compensation methods, but also the case with perfect channel state information (CSI) and no I/Q imbalance, due to additional frequency diversity obtained. The ICA based semi-blind LSFE receiver outperforms its OFDM counterpart significantly with a training overhead of only 0.05%.     

短波单载波空时分组码的频域均衡研究

短波通信受多径衰落、干扰复杂等影响严重。空时分组码(Space Time Block Code,STBC)技术在无需增加频谱资源和天线发射功率的前提下,可以利用多输入多输出(Multiple-Input Multiple-Output,MIMO)信道提供的分集增益提升传输可靠性。分析短波MIMO研究现状,提出短波单载波STBC频域均衡(Frequency-Domain Equalization,FDE)系统架构,针对短波信道引入的码间干扰研究MIMO MMSE-FDE均衡技术,并将单载波STBC频域均衡与时域均衡及短波现有波形进行仿真对比。仿真结果表明,相较于短波现有波形,单载波STBC频域均衡系统的可靠性有较大幅度提升,且性能与STBC时域均衡接近,但计算复杂度远低于STBC时域均衡。     

On blind identifiability of FIR-MIMO systems with cyclostationary inputs using second order statistics

We consider a general n/spl times/n multiple-input multiple-output (MIMO) system excited by unobservable inputs that are spatially independent, cyclostationary with unknown statistics. Such a MIMO scenario appears in many applications, such as multiuser communications and separation of competing speakers in speech processing. A special case of this problem, i.e., a 2/spl times/2 system case, was previously addressed in another work using frequency-domain correlations of the system output. In this paper, we provide a set of conditions under which a general n/spl times/n system is uniquely identifiable based on the second-order frequency-domain correlations of the system output. We provide a constructive proof for the uniqueness of the system solution, which could also serve as a basis for a practical algorithm for system identification.     

New transmit schemes and simplified receivers for MIMO wireless communication systems

In this paper, optimized transmit schemes for multiple-input multiple-output (MIMO) systems with simplified receivers are proposed for the downlink of high-speed wireless communication systems. In these systems, MIMO signal preprocessing is performed at the transmitter or base station with the receiver at the mobile station having a simplified structure that requires only limited signal processing. An important potential application for our transmit MIMO techniques is in the downlink of high-speed wireless communication systems with Vertical Bell Laboratories Layered Space-Time (V-BLAST) or a similar technique utilized in the uplink, creating a high-speed duplex system with a simplified mobile station transceiver structure. Two approaches are introduced and these depend on whether or not receive diversity is employed at the receiver. Both methods require that channel state information be available at the transmitter. In addition, some important associated issues such as peak-to-average power ratio requirements at the transmitter and robustness to downlink channel errors are also investigated and various solutions are proposed. Simulation results are provided and these show that performance improvement can be achieved when compared with other MIMO transmit schemes.