Cooperative Covert Communication in Multi-Antenna Broadcast Channels

With the gradual popularization of 5G communications,the application of multi-antenna broadcasting technology has become widespread.Therefore,this study aims to investigate the wireless covert communication in the two-user cooperative multi-antenna broadcast channel.We focus on the issue that the deteriorated reliability and undetectability are mainly affected by the transmission power.To tackle this issue,we design a scheme based on beamforming to increase the reliability and undetectability of wireless covert communication in the multi-antenna broadcast channel.We first modeled and analyzed the cooperative multi-antenna broadcasting system,and put forward the target question.Then we use the SCA(successive convex approximation)algorithm to transform the target problem into a series of convex subproblems.Then the convex problems are solved and the covert channel capacity is calculated.In order to verify the effectiveness of the scheme,we conducted simulation verification.The simulation results show that the proposed beamforming scheme can effectively improve the reliability and undetectability of covert communication in multi-antenna broadcast channels.

Multi-User Semantic Fusion for Semantic Communications over Degraded Broadcast Channels

Degraded broadcast channels(DBC) are a typical multiuser communication scenario, Semantic communications over DBC still lack in-depth research. In this paper, we design a semantic communications approach based on multi-user semantic fusion for wireless image transmission over DBC. The transmitter extracts semantic features for two users separately and then effectively fuses them for broadcasting by leveraging semantic similarity. Unlike traditional allocation of time, power, or bandwidth, the semantic fusion scheme can dynamically control the weight of the semantic features of the two users to balance their performance. Considering the different channel state information(CSI) of both users over DBC,a DBC-Aware method is developed that embeds the CSI of both users into the joint source-channel coding encoder and fusion module to adapt to the channel.Experimental results show that the proposed system outperforms the traditional broadcasting schemes.

A Deep Learning Based Broadcast Approach for Image Semantic Communication over Fading Channels

We consider an image semantic communication system in a time-varying fading Gaussian MIMO channel,with a finite number of channel states.A deep learning-aided broadcast approach scheme is proposed to benefit the adaptive semantic transmission in terms of different channel states.We combine the classic broadcast approach with the image transformer to implement this adaptive joint source and channel coding(JSCC)scheme.Specifically,we utilize the neural network(NN)to jointly optimize the hierarchical image compression and superposition code mapping within this scheme.The learned transformers and codebooks allow recovering of the image with an adaptive quality and low error rate at the receiver side,in each channel state.The simulation results exhibit our proposed scheme can dynamically adapt the coding to the current channel state and outperform some existing intelligent schemes with the fixed coding block.

Design Method for Optimizing the Interactive Interface of Live Broadcasting Platform for the Elderly Users

In the era of network live broadcasting for everyone,the development of live broadcasting platforms is also more intelligent and diversified.However,in the face of a large group of elderly users,the interface interaction design mode used is still mainly based on the interaction mode for young groups,and is not designed for elderly users.Therefore,a design method for optimizing the interaction interface of live broadcasting platform for elderly users was proposed in this study.Firstly,the case study method and Delphi expert survey method were used to determine the design needs of elderly users and the design mode was analysed.Secondly,the orthogonal design principle was used to design a test sample of the interactive interface of live broadcasting platform applicable for the elderly users,and then a user evaluation system was established to calculate the weights of the design elements using hierarchical analysis,and then the predictive relationship between the design mode of the interactive interface of live broadcasting platform and the elderly users was established by Quantitative Theory I.Finally,Genetic Algorithm was applied to generate the optimized design scheme.The results showed that the design method based on the Genetic Algorithm and the combination of Quantitative Theory can scientifically and effectively optimize the design of the interactive interface of the live broadcasting platform for the elderly users,and improve the experience of the elderly users.

Theoretical Analysis and Design Implementation of FM Broadcast Receiving System based on SDR

ADALM Pluto is a software-defined radio product.Based on theoretical analysis,this paper designs a Frequency Modulation(FM)broadcast receiving system using ADALM Pluto as a wireless receiver on the Simulink platform.The simulation results show that the theoretical analysis is correct and the parameter settings are reasonable,and the Software-Defined Radio(SDR)has the characteristics of high performance,high ease of use,and low cost.

基于DVB和IP双结构传输模式的复合流式虚拟视频点播系统设计

当虚拟视频点播系统遇到高访问量时会使其服务器负荷过大,导致视频传输速度下降、播放不连续。因此,设计一种基于DVB和IP双结构传输模式的复合流式虚拟视频点播系统,以适应用户需求和网络条件,动态调整视频流的传输质量和分辨率。构建基于DVB和IP双结构传输模式的复合流式虚拟视频点播系统框架,终端用户通过基础服务层的Web页面提交视频点播申请后,从视频编排层获取点播视频;控制层的播出控制模块调取PBHS算法来实现网络资源受限下的带宽自适应分配,以动态地调整不同带宽占用,优化网络资源利用,提高传输效率。通过视频传送模块输出点播视频,利用传输层的IP和DVB双结构传输模式将其输送到应用层,最终可视化呈现给用户。实验结果表明,所设计系统可实现虚拟视频点播,视频播放连续不卡顿、画面分辨率高,信令延迟仅34 ms,视频传输速度达到18 Mb/s,平均点播时间为1 320 ms,且拒绝用户数少。

Programming Technology of IP Multicast and Broadcast Based on Socket

Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcast based on socket is provided, according to TCP/IP protocol in LINUX system. The acquiring and converting of broadcast destination address and multicast address, the setting of multicast options, the joining in and withdrawing from the multicast group, and the receiving and sending of datagram are all demonstrated in it, the related system calls and simple explication of C programming are also included.

基于Broadcast模板的交互系统

本文提出了一种基于Ｂｒｏａｄｃａｓｔ模板开发交互系统的面向对象方法，并分析了此方法所带来的系统结构的清晰性、稳定性及软件部件的可重用性。

广播标记(Broadcast Flag)技术

近来,业界都在讨论广播标记(BroadcastFlag)技术。本文详细介绍了广播标记技术产生的背景、原理与实现,以及争论的焦点问题;最后针对广播标记技术是否可以应用于我国的数字电视领域给出了我们的看法和建议。

Wireless location algorithm using digital broadcasting signals based on neural network

In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. By the learning ability of the NN and the closely approximate unknown function to any degree of desired accuracy,the input-output mapping relationship between coordinates and the measurement data of time of arrival （TOA） and time difference of arrival （TDOA） is established. A real-time learning algorithm based on the extended Kalman filter （EKF） is used to train the multilayer perceptron （MLP） network by treating the linkweights of a network as the states of the nonlinear dynamic system. Since the EKF-based learning algorithm approximately gives the minimum variance estimate of the linkweights,the convergence is improved in comparison with the backwards error propagation （BP） algorithm. Numerical results illustrate thatthe proposedalgorithmcanachieve enhanced accuracy,and the performance ofthe algorithmis betterthanthat of the BP-based NN algorithm and the least squares （LS） algorithm in the NLOS environments. Moreover,this location method does not depend on a particular distribution of the NLOS error and does not need line-of-sight （ LOS ） or NLOS identification.

使用Broadcast Disks方法分布的空中位图索引

提出一种使用BroadcastDisks算法来分布位图索引的空中索引方法,根据数据项访问概率,使用位图作为数据广播的索引,减少了移动终端等待数据时保持激活状态的时间,达到节能的目的。

天拓五号卫星天基物联网系统关键技术与在轨验证

天基物联网是地基物联网的有效补充和延拓,是建设万物互联、泛在感知的基础性技术手段。以天拓五号卫星中集成的天基物联网系统为例,瞄准覆盖陆海空的多域多场景应用需求,重点解决船舶自动识别系统信号、广播式自动相关监视系统信号的高可靠侦收以及数据搜集系统的多址接入问题,实现航海目标、航空目标的实时监管以及极海量窄带物联传感终端的全球布局,为我国天基物联网的论证、建设、发展以及规模应用提供借鉴方案。

基于区块链的车联网跨域数据安全传输系统设计

为有效应对车联网系统在数据传输过程中的安全问题,提出一种基于区块链的车联网跨域数据安全传输系统。该系统将车联网安全数据传输过程划分为注册、安全通信与数据共享三个关键环节。在注册阶段,车辆和路边单元需要通过可信机构完成注册,以确保其的身份合法性;在通信阶段,为了减少路边单元与车辆频繁认证,设计了跨域认证的方法,保障数据传输的可靠性和完整性,并引入假名来保护用户隐私;在共享阶段,文中设计了基于多线程遍历共享广播森林的事务广播算法,利用广度优先搜索思想建立广播森林,并使用多线程遍历进行数据事务广播传输。实验仿真结果显示,文中方案的签名计算成本减少70%,验证计算成本减少41%;其次,在ER模型下,相比使用Gossip协议进行事务数据传输,该方案中交通数据事务总时间降低了93%;在BA模型下降低了87%。

Godson-T众核体系结构上的Broadcast性能优化

Godson-T是中国科学院计算技术研究所计算机系统结构重点实验室先进微系统组正在研制开发的适合于超深亚微米工艺实现的大规模片上众核系统.Godson-T片上存储的单端口结构节省了芯片面积但制约了共享数据的读取效率.直接在Godson-T上实现传统的Broadcast算法需要大量的同步互斥开销,无法达到很好的性能提升.基于Godson-T体系结构,对数据共享的重要并行算法Broadcast进行优化,提高了Godson-T体系结构下的数据共读的效率.主要采取了以下3项技术:消除大规模的线程同步,建立源地址到目的地址的映射表和用汇编语言实现Broadcast的核心部分.优化后Broadcast在小核数为32时即可达到5.8倍加速比.

基于广播电视卫星的双基海杂波建模与实测数据分析

针对无源雷达系统中的海面目标检测场景,提出了一种基于卫星发射源的海面回波信号仿真方法,得到理论仿真的双基海杂波数据。考虑卫星位置、接收机高度以及接收天线的波束宽度等因素,将海面照射范围划分成小面元,基于海面的电磁散射以及运动速度,利用卫星发射信号调制,得到具有物理机制的海杂波;同时实测得到中星九号照射下的双基海杂波,利用实测数据验证了理论仿真的有效性,并进一步对仿真数据进行分析。

NE-Gossip:基于邻居节点评估机制的Gossip广播算法

与传统中心化架构的系统相比,去中心化的区块链网络吞吐量仍处于较低水平。为此,许多研究从共识机制、分片机制等对区块链的可扩展性进行了探索。然而,随着吞吐量的提升,区块链系统对底层消息广播网络效率的要求也在不断提高。由此,着眼于底层P2P消息广播网络,在Gossip的算法中引入邻居节点评估机制,提出NE-Gossip广播算法,根据评估结果在消息转发时选择具有更好消息转发能力的节点。实验结果表明,在同样的广播冗余度下,NE-Gossip算法在广播覆盖率上具有更好的表现。

基于TD-OFDM的MESH自组网络广播信道设计方法

针对Wi-Fi MESH各节点发送数据时会发生丢包的现象,导致通信传输可靠性不高的问题,提出了一种基于TDOFDM的MESH自组网络广播信道设计方法。首先,进行帧结构设计,设计广播子帧和数据子帧的结构。接着,进行时间同步,同步完成后数据在物理层进行一系列流程,完成整个广播信道的设计。经过仿真,实验结果表明将物理广播信道加入MESH组网后对比基于Wi-Fi的MESH组网,自组网碰撞和重传大大减少,正确接收码字的概率提升了18.6%,提高了通信传输的可靠性。

地市级国产化广播制播系统建设实践

目前,信息系统项目必须按照政府采购需求标准要求进行建设,在媒体融合的大潮中,打造适应广播品牌美誉度和市场竞争力的信创基础底座技术平台尤为迫切。本文以广安市融媒体中心的广播融媒制播系统建设实践为例,介绍系统平台设计、功能设计和系统建设等相关内容。

广播电视发射台播出信号检测报警器设计制作分析

为提高电视广播节目的播出质量和效率,降低停播故障的发生概率,本文首先简要分析了广播电视发射台节目传播的常见故障问题,然后从信号检测转换电路、报警控制电路以及多路报警系统等多个维度出发,重点阐述了广播电视发射台播出信号检测报警器关键的设计制作技术。研究结果表明,利用现代科学技术,综合研发制作检测报警器,能够实现对广播电视发射台播出信号的动态检测,减少故障问题的出现。

广播电视工程系统接地技术分析

在广播电视工程中,接地技术具有十分重要的作用,其性能的优劣直接关系到广播电视系统运行的质量。因此,为了有效保证广播电视工作的质量,推动广播电视工作的顺利进行,必须对接地技术给予高度的重视。本文首先阐述了接地技术的基本原理,然后详细分析了接地技术的几种类型,探讨接地技术应用中需要注意的事项,以期提高广播电视工程接地系统安全。