级联RS-空时格码OFDM系统的应用

提出了级联RS-空时编码的OFDM系统方案,分析了在无线衰落信道中的性能并给出了性能仿真结果,结果表明该系统能充分利用所有的分集资源,获得相当大的分集增益和编码增益.     

Space-Time Complementary Coding MIMO with Joint Spatial Diversity and Multiplex Capability

This paper introduces a new space-time coding scheme, namely Space-Time Complementary Coding (STCC) scheme. With the help of pair-wise complementary codes, an STCC MIMO system can achieve both spatial diversity and multiplex transmission. The scheme requires neither bandwidth expansion nor feedback information from receiver, and it offers a nearly interference-free and multipath-resist performance due to a widely open interference-free window of the pair-wise complementary codes. The analytical results reveals that it provides a uniquely high diversity-multiplex gain product for its applications in flat or frequency-selective fading channel.     

Performance Analysis of Combined Space Time Block Coding with Generalized Selection Combining in Underlay Cognitive Radio

Wireless Personal Communications - In this paper, we demonstrate the performance analysis of an underlay MIMO cognitive radios employing space time block coding at secondary’s user...     

On the Performance of Golden Space-Time Trellis Coded Modulation over MIMO Block Fading Channels

The Golden space-time trellis coded modulation (GST-TCM) scheme was proposed in [1] for a high rate 2 × 2 multiple-input multiple-output (MIMO) system over slow fading channels. In this letter, we present the performance analysis of GST-TCM over block fading channels, where the channel matrix is constant over a fraction of the codeword length and varies from one fraction to another, independently. In practice, it is not useful to design such codes for specific block fading channel parameters and a robust solution is preferable. We then show both analytically and by simulation that the GST-TCM designed for slow fading channels are indeed robust to all block fading channel conditions.     

The Optimization of Combined Beamforming with Space-Time Block Coding

The combination of beamforming and Alamouti space-time block coding may not be optimal in rich scattering since it only uses two equal energy loading beams. A new scheme combining beamforming with spacetime block coding is put forward in this paper. The new scheme requires only the knowledge of channel correlation at the transmitter, the optimization design turns out to be an eigen-beamformer with multiple beams pointing to orthogonal directions along the eigenvectors of the channel correlation matrix and combine with appropriate spacetime block coding. In order to minimize a tight upper bound on the symbol error rate the optimal energy loading algorithm is proposed in this paper. We assume that the channel receive vectors observed on different receive antennas are mutually uncorrelated, but have the same correlation matrix, thus the new scheme can be extended to multiple receivers. The combination of beamforming and Alamouti space-time block coding is a special case of the new scheme. Based on Laplace transform, this paper provides an algorithm to calculate the probability density function of the equivalent signal to noise ratio, thus the closedorm expressions for the symbol error rate of the new scheme are derived. Simulation results demonstrate the superiority of the new scheme.     

Cognitive Radio MIMO Gaussian Broadcast Channels with the Power Constraint

The cognitive radio multiple-input multiple-output Gaussian broadcast channels are studied where multiple antennas are available for both primary users and secondary users in a spectrum sharing environment, and the sum-rate capacity is also obtained under both the SUs’ transmit power constraint and interference power constraint at the primary receivers. The paper principally consists of two steps. First, a duality technique and dirty paper coding are adopted to simplify the channels. Second, we propose an iterative power allocation algorithm to obtain the maximum sum-rate capacity and examine the effects of the constraint parameters on the concerned quantities. Finally, numerical simulation results are presented to validate the proposed theoretical analysis.     

Optimization of Trellis Codes with Multilevel Amplitude Modulation with Respect to an Error Probability Criterion

An easily computed upper bound on the error probability of a data communications system with combined trellis coding and multilevel/phase modulation is derived, assuming an additive white Gaussian noise channel and maximum-likelihood decoding. This bound is used to search for codes obtained by set-partitioning that minimize the bound for a fixed number of trellis states. Only amplitude modulated signals typically used in voiceband modem applications are considered. The signal levels that minimize the error probability bound subject to an average power constraint are presented for some specific codes.     

On the Performance Analysis of Multi-User Massive MIMO Systems with Error Vector Signals for 5G Cellular Networks

Wireless Personal Communications - Cellular networks have been evolving at a great pace recently to keep up with the rapidly increasing demand for wireless data services. To cater for this demand,...     

Application of Cognitive Radio in TV and Radio Field

介绍了认知无线电技术的发展背景和当前的研究状况,论述了发展认知无线电的重要性,讨论了认知无线电领域的几种关键技术,论述了认知无线电在广电领域的应用范围和发展前景.举例说明了广电运营商可通过认知无线电系统接入除传统电视业务之外的多种业务.     

Massive MIMO在5G中的应用与挑战

5G无线技术有望建立一个丰富、可靠的超连接世界。但是无论是较高的通信频段、更高的带宽需求、极为高效的天线收发方式,亦或是新的波束赋形技术,5G NR(新空口)都提出创新性的设计。文章阐述单用户和多用户Massive MIMO(大规模多输入多输出)技术原理,分析Massive MIMO的应用背景,在此基础上指出MassiveMIMO的应用优势,并论述其在5G中的应用及挑战。     

有信道估计误差MIMO MRC系统性能研究

利用维希特随机矩阵理论和矩生成函数方法,推导了有信道估计误差的独立瑞利衰落信道上采用多输入多输出（MIMO）最大比合并（MRC）天线分集方案的矩形M进制正交幅度调制（MQAM）的平均误符号率（SER）解析表达式。数值计算结果阐明了信道估计误差和收发天线数对矩形MQAM调制MIMO MRC系统误码性能的影响。     

结合认知无线电的军事通信频谱管理研究

介绍了认知无线电的基本思想,分析了当前军事通信频谱管理由于其静态管理模式和较低的自适应能力所带来的局限性,探讨了未来军事通信频谱管理的发展方向,提出了一种引入认知无线电概念的频谱管理模式,并分析了这一新的管理模式所带来的好处。该模式的主要特点包括：动态频谱管理、监控装备与通信装备的融合、集中管理与分布式管理相结合等。最后,分析了目前需要解决的技术难题。     

联合LDPC码的多级编码调制迭代判决仿真分析

论文介绍了多级编码调制的基本原理和译码算法,以LDPC码作为多级编码调制的分量码,在译码过程中引入了迭代思想,分析了一种适用于多级编码调制的迭代判决算法,并建立了MLCM-ID系统模型.计算机仿真表明,该算法能够有效地提高系统性能,具有一定的应用价值.     

认知无线电关键技术及应用简

频谱资源成为无线通信的一个重要问题和制约无线通信发展的新瓶颈.认知无线电(Cognitive Radio,CR)技术成为解决频谱资源匮乏问题的有效方法.本文基于认知无线电在无线通信中的重要作用,介绍了认知无线电的概念,总结了认知无线电的关键技术,概述了认知无线电的应用情况,研究了主管部门在认知无线电下的频谱管理工作.     

ZF and MMSE Detectors Performances of a Massive MIMO System Combined with OFDM and M-QAM Modulation

Wireless Personal Communications - This paper presents a least squares channel estimation (LSCE) in the UpLink transmission for a Massive MIMO systems in 5G wireless communications, combined with...     

认知无线电技术在地空数据链系统中的应用浅析

将认知无线电思想引入到地空数据链组网系统中,提出了地空认知无线通信系统的概念,并重点探讨了地空认知无线通信系统的自适应功率控制应用。在自适应功率控制需求分析的基础上,明确了功率控制的典型应用场景,提出了自适应功率控制的总体实现方法,并以JTIDS数据链为对象分析了其关键技术的解决方案。     

On the Sum Rate Capacity of MIMO Broadcast Channels in Cognitive Radio Networks with Interference Power Constraints

This paper investigates the sum rate capacity of MIMO broadcast channels (MIMO-BCs) in cognitive radio networks. A suboptimal user-selection algorithm is proposed to achieve a large sum rate capacity with reduced complexity. This algorithm consists of two steps. First, zero-forcing beamforming is utilized as a downlink precoding technique that precancels inter-user interference. Second, singular value decomposition is applied to the channel matrices of all the secondary users and only consider the singular vectors corresponding to the maximum singular values. The proposed user-selection algorithm chooses singular vectors which are nearly orthogonal to each other and nearly orthogonal to the vector of primary users. With this algorithm, the sum rate capacity of MIMO-BCs in CR networks with interference power constraints and transmit power constraints is derived. We formulate the sum rate capacity as a multi-constraint optimization problem and develop an algorithm to solve the problem in its equivalent form. Finally, numerical simulations are conducted to corroborate our theoretical results in flat Rayleigh fading environments. It is shown that the proposed algorithms are capable of achieving a large sum rate capacity with a very low complexity.     

BER Analysis of M-QAM with Packet Combining Over Space-Time Block Coded MIMO Fading Channels

We analyze the bit error rate (BER) performance of M-ary quadrature amplitude modulation (M-QAM) when using space-time block coding (STBC) along with packet combining triggered by automatic repeat request (ARQ) retransmission over multiple-input multiple-output (MIMO) fading channels. Specifically, adopting a log-likelihood ratio (LLR) based approach and considering the 16-QAM case of study, we provide an exact formulation for the aggregate LLR distribution in the case the STBC codeword can be transmitted twice, and derive the resulting BER. For higher number of retransmissions, an approximation of the error function is used to derive the LLR distributions and the system's ensuing BER. Considering different values of combined transmissions and M-QAM with possible constellation rearrangement (CoRe), validation of the proposed BER analytical model through simulations and assessment of the advantages of packet combining are provided for transmissions over additive white Gaussian noise (AWGN) channel and orthogonalized MIMO Rayleigh fading channels with different STBC mappings.     

Uplink Sum-Rate Analysis of Massive MIMO System with Pilot Contamination and CSI Delay

We consider multi-cell multi-user massive MIMO system under correlated Rayleigh fading channels. Taking pilot contamination and CSI delay into consideration, we derive the equivalent channel model with MMSE channel estimation and one-tap prediction. Employing this equivalent channel model, the lower bound of the uplink sum-rate is derived, and its asymptotical performance is studied when the base station antenna number goes without bound. We find that if we schedule the \(k\) -th user of all cells who have the same prediction coefficient, the uplink sum-rate is the same as the one with no CSI delay when the number of BS antennas goes without bound at a much greater rate than the number of users. Simulation results show that the asymptotic approximation has good performance for large \(M\) , and suggest that large antenna array can compensate for the decay due to CSI delay. Simulation results also verify our guess that CSI delay does not necessarilly decrease the uplink sum-rate due to the impact of pilot contamination.     

The Combined Effects of Noise and Multipath Propagation in Multilevel PSK Radio Links

A general analysis of the behavior of multilevel PSK radio links is carried out under multipath propagation conditions. A method is proposed to evaluate system unavailability due to the combined effects of noise and faded channel distortion. The "outage domain," having fixed the transmission channel, is calculated in the space of the variables which characterize any anomalous propagation condition. In particular, with reference to a "twopath model" (a "direct ray" and an "echo"), variations of carrier and symbol synchronisms due to the echo are taken into account and their importance is emphasized in realizing the numerical results. These are shown to be in very good agreement with the experimental ones which have appeared in the literature. An analytical realization of the results obtained is developed and leads to a simple asymptotic formula explaining outage probability as a function of some parameters of the echo statistics, the transmission channel adopted, and the number of modulation levels. Rapid evaluation of this formula allows us to plot outage probability as a function of spectral efficiency, measured in bits/s/Hz.