AM—SCM光波技术的发展和展望

本文介绍了副载波复用的光通信技术的基本原理，２种调制方式的性能比较，ＡＭ－ＳＣＭ技术在ＣＡＴＶ网上的应用和发展。     

高副载波复用光纤CATV系统的优化设计

高副载波复用（ＳＭＣＭ）ＡＭ－ＶＳＢ ＣＡＴＶ系统在国内正日渐引起人们的关注。本文提出了采用掺饵光纤放大器（ＥＤＦＡ）和线性化外调制器在系统中进行优化,以实现高副载波复用。并首次采用定量的无约束数值优化法,即单纯形法,对全系统中一些关键参数进行优化,从而为ＭＳＣＭ ＡＭ－ＶＳＢ ＣＡＴＶ系统的优化提供了一种有实际意义的通用方法。     

基于小波包变换的多址通信

新一代无线通信系统要求大容量、高速率、综合业务、适用于各种环境。为满足上述要求,宜采用ＣＤＭＡ／ＴＤＭＡ／ＦＤＭＡ混合多址方式,其中多载波ＣＤＭＡ已成为目前研究热点。本文提出一种基于小波包变换的多载波ＣＤＭＡ或正交小波包分解复用（ＯＷＰＤＭ）－ＣＤＭＡ通信方式,介绍了其基本结构和主要优点。这是一种很有发展前景的多址通信技术。     

提高卫星通信系统容量的一种新技术

本文介绍了双和卫星通信领域的一种崭新的技术即对称载波复用（ＰＣＭＡ）技术,对称载波复用是一种全新的卫星系统的频率复用方式,利用它可将现有的卫星通信系统的容量提高１倍。文章分析了ＰＣＭＡ的基本原理,实现方案,最后给出了性能分析以及应用前景。     

中国卫星电视分配信道副载波传送NICAM－728数字立体声技术 第三讲 调制和传输

中国卫星电视分配信道副载波传送ＮＩＣＡＭ－７２８数字立体声技术第三讲调制和传输高少君（广电部广播科学研究院）１视频和调频电视伴音在卫星电视分配信道副载波传送ＮＩＣＡＭ－７２８数字立体声系统中，卫星电视调制参数仍依照国标ＧＢ１１４４３“国内卫星通信地球...     

卫星电视分配信道副载波传送数字立体声（NICAM－728）推广使用情况

卫星电视分配信道副载波传送数字立体声（ＮＩＣＡＭ－７２８）推广使用情况季淑芝（广电部广科院广播所）广播电影电视部决定从１９９５年３月１日起正式采用中国卫星电视分配信道副载波传送ＮＩＣＡＭ７２８数字立体声技术，通过中星五号（现改为亚太ＩＡ）ＣＣＴＶ－１...     

多路FM—SCM光波系统研制

介绍我们研制的多路ＦＭ－ＳＣＭ（调频副载波复用）光波系统及其性能，讨论了ＳＣＭ光波系统的噪声。该系统主要可用于多路ＣＡＴＶ光纤传输。采用Ｆ－Ｐ腔ＬＤ和ＰＩＮ－ＦＥＴ接收组件，通过系统优化，实现了接收端输出电视图象信号ＳＮＲ〉５５ｄＢ。     

多路FM－SCM光波系统研制

介绍我们研制的多路ＦＭ－ＳＣＭ（调频副载波复用）光波系统及其性能，讨论了ＳＣＭ光波系统的噪声。该系统主要可用于多路ＣＡＴＶ光纤传输。采用Ｆ－Ｐ腔ＬＤ和ＰＩＮ－ＦＥＴ接收组件，通过系统优化，实现了接收端输出电视图象信号ＳＮＲ＞５５ｄＢ。     

中国卫星电视分配信道副载波传送NICAM－728数字立体声技术──第二讲 NICAM－728编码原理

中国卫星电视分配信道副载波传送ＮＩＣＡＭ－７２８数字立体声技术──第二讲　ＮＩＣＡＭ－７２８编码原理高少君（广电部广播科学研究院）ＮＩＣＡＭ－７２８数字声编码的基本流程如图１所示。来自演播室的两路声音信号或一路立体声的左右声道信号经过Ｊ１７预加重，再...     

正交复用QAM系统的定时和载波相位跟踪新算法

在数字信号传输系统中，正交复用ＱＡＭ（ＯＭＱＡＭ）是目前最有效的一种抗信道失真传输技术，但它对系统的定时偏移和载波相位误差非常敏感。本文基于高阶累积量技术，导出了一种新的ＯＭＱＡＭ系统定时和载波相位的跟踪算法。计算机仿真证实了这一理论分析结果，并同原有的Ｈｉｒｏｓａｋｉ算法做了比较     

多输入多输出系统中的预编码技术研究

MIMO系统中的预编码技术,利用信道信息,使发射信号和空间信道相匹配,有效的对抗信道衰落,提高系统误码率和频谱利用效率,已成为无线通信技术的研究热点。本文首先对MIMO系统模型和容量进行了简单的介绍,然后分析了基于不同角度的预编码技术,其中主要针对基于信道预测的预编码技术的预测算法进行了研究。     

Tomlinson-Harashima precoding for the magnetic recording channel

A new view on Tomlinson-Harashima (TH) precoding demonstrates the applicability of this precoding technique to input restricted channels. TH precoders of this kind are derived, and a hybrid of decision feedback equalisation and TH precoding is proposed     

BER and Capacity Improvement for Multiuser MIMO System by MRT Precoding Technique

In recent years several of endeavors have been conducted in various papers to improve capacity and bit error rate performance of multiuser MIMO system. Every effort tried to increase gain of the individual stream between base station and users’ antennas while reducing the interference among multiple users and interference between streams of single user itself. All these papers adopted precoding techniques for beam forming of individual stream. Various papers have compared precoding techniques such as DPC, BD-ZF, BD-MMSE, BD-QR-MRL, and BD-QR-LRL. Block diagonalization technique is capable to reduce multiuser interference, but not able to combat interference between antennas of single user itself. BD combines with other techniques to overcome this problem. This paper also proposes a precoding technique called modified maximum ratio transmission, which is able to deal with the problem without much complexity. Simulation is done to compare all precoding technique with MRT. The paper tests the precoding techniques on the parameters of BER and capacity, to achieve optimum receiver performance. BER curve and capacity curve are plotted to conclude the paper.

     

A high-speed phosphorescent LED-based visible light communication system utilizing SQGNRC precoding technique

Peak-over-average power ratio (PAPR) control utilizing precoding technique based on square root-generalized raised cosine function is proposed and verified experimentally through a visible light communication system employing phosphor-based white light-emitting diodes for the first time. The simulation results show that the improved precoding matrix can further reduce PAPR by nearly 1 dB compared with existing precoding matrix based on square root raised cosine function and significantly achieve 3.5 dB improvement in contrast to original signals without precoding. The experimental result also proves that the bit error rate performance can be effectively improved by 1.62 dB at the same bandwidth and 0.76 dB at the same raw data rate in terms of quality factor when proposed precoding technique is applied, which clearly demonstrates its benefit and feasibility.     

Deep frameworks based on residual dense network and reinforcement learning for mmWave massive MIMO systems

In millimeter wave (mmWave) massive multiple-input-multiple-output (MIMO) systems, hybrid precoding plays a pivotal role in reducing complexity and cost while providing a good spectral efficiency. However, implementation of digital precoders with large number of antennas is difficult due to hardware constraints, while analog precoders offer confined performance. This leads to high computational complexity and cannot fully exploit the spatial information. Previous studies on hybrid precoding were based on exhaustive search solutions or greedy schemes, which result in higher complexity system performance. To face these challenges, this paper proposes deep hybrid precoding framework with phase quantization and residual dense network to design the matrix of analog and digital precoders. The proposed deep hybrid precoding technique consists of offline training stage and online deployment stage. In offline training stage, hybrid precoding is obtained assuming the approximate phase quantization. While in the online deployment stage, the matrix of analog precoding is calculated by exchanging approximate phase quantization with ideal phase and grouping the analog precoding vectors. In this paper, we also propose a deep reinforcement learning-based hybrid precoding. It consists of a deep reinforcement learning with employing convolutional neural network and long short-term memory (LSTM) methods. In our proposed frameworks, structures of proposed techniques are trained for maximum spectral efficiency. Our proposed techniques are compared with other precoding techniques. Results illustrate that the proposed techniques outperforms the other precoding techniques in terms of the spectral efficiency.     

多用户MIMO系统基于消息块预编码的可信通信技术

针对多用户MIMO窃听信道,提出了在未知非法接收者任何信息的前提下,实现可信通信的基于消息块的人为干扰和预编码算法,并且在实现可信通信"可信性"的同时,考虑了"有效性"和"效率"问题。人为干扰仅干扰非法接收者,而不对合法接收者产生任何影响。预编码算法是已有的用于消除多用户干扰的"迫零"方式与基于SVD分解的线性预编码方式的结合。与基于单消息符号的预编码方式相比,提高了可信通信的效率。仿真结果表明,其进一步降低了非法接收者的SINR,并提高了多用户MIMO系统的通信容量。     

多用户MIMO系统下行链路的随机多波束复用技术

该文提出了一种随机多波束多用户复用技术,充分利用多用户分集以及基站多天线的空间自由度来提高系统吞吐量。不同于传统的随机波束形成技术,该技术首先在给定预编码码本内随机选取一个码字,然后调度多个空分复用用户以及其余预编码矩阵。该文采用了一种逐次调度的方式,第一次训练调度一个主发送用户并确定一个次发送预编码矩阵,通过第二次训练选择次发送用户,这种方式能以很小的反馈开销有效控制复用用户之间的相互干扰。同时,该文所提技术能进一步推广到用户具有不同天线配置的异构情形。仿真结果表明,该文技术在具有不同相关性的信道环境下都能获得较优的系统吞吐量。     

基于SLNR预编码的感知无线电技术

感知无线电技术允许多个感知用户之间公平协调共享频谱,由于基站在同一频率同一时隙下可以和几个移动终端同时通信,这将引起用户间的共信道干扰（CCI）。本文引入了预编码的思想,多个感知用户感知并共享频谱时在发射端加入预编码矩阵,基于信漏噪比（SLNR）的预编码同时消除了共信道干扰（CCI）和噪声,提高了感知系统性能。仿真结果说明采用了基于SLNR的预编码后系统性能得到了明显改善,且发射天线数越多,系统性能越好。     

A Novel Lattice Reduction Precoding Method

In this work, a novel lattice reduction (LR) precoding method is proposed. The technique combines conventional LR precoding with a method of reducing the singular value coefficients of the LR-reduced basis matrix. The performance of the new technique was comparable to that of sphere encoding, while its complexity was lower than that of other sub-optimal methods.     

Interpolation Based Unitary Precoding for Spatial Multiplexing MIMO-OFDM With Limited Feedback

Spatial multiplexing with linear precoding is a simple technique for achieving high spectral efficiency in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. Linear precoding requires channel state information for each OFDM subcarrier, which can be achieved using feedback. To reduce the amount of feedback, this paper proposes a limited feedback architecture that combines precoder quantization with a special matrix interpolator. In the proposed system, the receiver sends information about a fraction of the precoding matrices to the transmitter and the transmitter reconstructs the precoding matrices for all the subcarriers. A new interpolator is proposed inspired by spherical interpolation that respects the orthogonal columns of the precoding matrices and the performance invariance to right multiplication by a unitary matrix. The interpolator is parameterized by a set of unitary matrices; a construction of a suitable set is briefly described. Simulations illustrate the performance of limited feedback precoding with coding, estimation or prediction error, and time variation for bit error rate (BER), mutual information, and mean squared error (MSE)