Design of the D2D multicast transmission scheme in the LTE communication system

In order to improve spectrum efficiency and transmission reliability of the LTE communication system, its terminal users can be divided into the D2D communication cluster. Specially, the multicast transmission of data packets in the LTE system can be realized through two hop transmissions, namely, the base station multicasts data packets to all cluster-heads and each cluster-head in the D2D communication cluster broadcasts the received packets. Considering that the links may be unreliable in the D2D communication cluster, the ARQ retransmission algorithm based on network coding is adopted. By establishing the lost-packet list, the cluster-head operates the lost-packets by network coding, and broadcasts the encoded packets to reduce the number of retransmission. Performance analysis and simulation results show that the proposed scheme can achieve almost the same transmission efficiency as the existing scheme, but has a lower computational complexity. Compared with the traditional multicast retransmission scheme based on network coding in the cellular communication mode, the scheme only retransmits the lost-packets in D2D cluster, to reduce the pachets transmission number of base stations and decrease the spectrum resource consumption of the cellular network effectively at a high packet loss rate.     

基于D2D通信的V2X资源分配方案

针对基于设备到设备(D2D)的汽车间通信复用蜂窝资源带来的干扰问题,考虑在满足车辆用户(V-UEs)的通信要求下,通过一个启发式算法最大化蜂窝用户(C-UEs)总的吞吐量.首先通过图着色原理将没有干扰的车辆分在同一簇;其次根据分簇结果,利用改进的匈牙利指派算法为V-UEs分配信道;最后通过调整功率最大化C-UEs总的吞吐量.仿真结果表明,此算法能够很好地解决车通信(V2X)的同层干扰和跨层干扰问题,在保证V-UEs通信可靠性的前提下,提高了频谱利用率.     

Performance and Improvement of MCS Selection with Channel Quality Estimation Errors for HSDPA

The high-speed downlink packet access(HSD-PA)[1,2]is currently being standardized in3GPPforrelease5and release6.The main goal of HSDPAisto allow wideband code division multiple access(WCDMA)to support downlink peak data rates inthe range of approxi mately8-10Mbit·s-1for besteffort packet-data services[3,4].One major link adaptation(LA)technique em-ployedfor HSDPAis adaptive modulation and coding(AMC).The principle of AMCistochangethe mod-ulation and coding scheme(MCS)in accordan…     

Performance and Improvement Quality Estimation of MCS Selection with Channel Errors for HSDPA

The throughput performance of modulation and coding schemes （MCS） selection with channel quality estimation errors （CQEE） is analyzed for high-speed downlink packet access （HSDPA）. To reduce the loss of throughput caused by CQEE, the robust MCS selection method and adaptive MCS switching scheme are proposed. In addition, automatic repeat request （ARQ） scheme is used to improve the block error rate （BLER） performance. Simulation results show that the proposed methods decrease the throughput loss resulted from CQEE efficiently and BLER performance gets better with ARQ scheme.     

结合自适应调制和ARQ的跨层最优联合设计

考虑了一个结合自适应调制和自动重传请求的蜂窝下行系统,基站通过接收端的反馈获得其信道信息,然后在物理层通过自适应地选择调制和编码方式来最大化系统频谱效率,同时还在数据链路层采用自动重传技术来提高传输的鲁棒性.研究了在业务的平均延时约束下,通过最优选取自适应调制参数来最大化系统的频谱效率的方法.首先通过合理的假设对上述系统数学建模,然后将研究的问题建模为一个凸优化问题,并最终通过经典的拉格朗日乘数法给出了最优解.数值仿真表明本算法是最优的.     

基于WPD和(2D)~2PCA的步态识别方法

为了提高步态识别率,在步态能量图(gait energy image,GEI)基础上,提出了基于小波包分解(waveletpacket decomposition,WPD)和完全主成分分析(two-directional two-dimensional principal component analysis,(2D)2PCA)的步态识别方法.该方法采用基于人体轮廓的GEI来解决步态数据量过大的问题,并采用WPD和(2D)2PCA进行步态特征提取,解决了已有基于小波变换的步态识别方法中高频分量丢失或维数过高问题.在NLPR步态数据库上对该方法进行了评测,并与经典方法进行了比较.实验结果表明:该方法具有更高的识别率和视角变化的鲁棒性.     

选择重发型一点对多点(PMP)数据通信协议

本文提出了一种用于卫星广播信道的选择重发型一点对多点数据通信协议,并进行了理论分析和计算机模拟.结果表明,选择重发型 PMP 协议的性能优于集中反馈选择重发型 PMP 协议.在信道速率越高时,这种优势越明显.     

基于复数域网络编码的D2D传输方案设计

终端直通（D2D）用户在复用蜂窝网络频谱资源提高频谱效率的同时,不可避免地会受到蜂窝用户的干扰,为此该文提出一种基于复数域网络编码的D2D传输方案。D2D用户复用蜂窝下行链路频谱,将蜂窝基站和D2D发送端作为两个独立的信源,蜂窝用户作为中继节点。蜂窝用户对检测到的蜂窝信号和D2D信号进行复数域网络编码,D2D接收端采用最大似然多用户检测恢复出D2D信号,消除蜂窝用户对D2D用户的信号干扰。理论分析与仿真结果表明,该方案较传统的D2D传输方案,在确保消除蜂窝信号干扰的同时,能显著提高系统可达速率,降低符号错误概率。     

基于QoS的D2D资源分配算法

D2D通讯技术是5G通讯的一项关键技术,其最大的特点是数据无需经由基站转发并且能够有效地提升系统容量,提高频带利用率.但是它也存在一定缺陷,由于通讯过程中会占用原有蜂窝信道,D2D用户会对原始的小区用户产生干扰,并且这是一个两种用户相互干扰的过程.因此,D2D资源分配成为D2D技术引入的关键.为了克服在“一对一”D2D频谱分配过程中,每个D2D对仅可以占用一个移动信道的分配方式下,新加入D2D用户不一定会使得总容量变大这一问题,文中提出的算法兼顾了资源分配与功率控制两个方面.实验结果表明,在规定每对D2D用户可占用多个基站小区信道,新加入D2D用户不能使系统总容量减小的条件下,新的算法能有效地提升D2D用户总容量.     

Optimal power allocation and optimal relay selection for D2D communication

Cellular users can be regarded as relay nodes in cooperation with the Device-to-Device (D2D)communication so as to lower the cost, improve spectrum efficiency and solve the problems of network coverage, as well as improving service quality. In this paper an optimal power allocation and optimal relay selection algorithm based on network coding is proposed for using cellular users in the bidirectional relay nodes system. By fixing the total power of the D2D link to be transmitted, this algorithm optimizes the transmission power of each node, and selects the relay node which can maximize the channel capacity of the D2D link as the best relay node. Simulation results show that compared with other protocols, the proposed protocol can significantly improve the channel capacity of the D2D link.     

基于D2D的C-V2V车载协作通信资源分配算法

针对基于设备到设备(device-to-device,D2D)的蜂窝网络下车载无线通信技术(cellular-vehicle to everything,CV2X)中复用蜂窝用户资源带来的能效问题,提出了一种能效优化算法.通过新的功率控制方法最大化车载用户(vehicle user,V-UE)总能效,并利用能量收集技术...     

未知室外环境下移动机器人的三维场景重建

针对传统最近点迭代（iterative closest point,ICP）算法的局限性与大型室外场景的特点,在处理算法速度、算法精度以及迭代陷入局部最小问题等多个方面提出了改进的ICP配准算法.并且在处理多帧匹配问题时,提出了新的在线多帧匹配方法与减小累积误差的离线多帧匹配方法.利用改善的ICP算法与多帧匹配方法,依靠三维激光雷达与移动机器人,重建了室外场景,形成了完整的室外三维地图,为实现未知室外环境下移动机器人的定位与导航打下基础.实验表明,该方法快速、精度高、鲁棒性强,适用于重建大型复杂的室外环境.     

适用于三维有限元网格显示的逐步消隐法

在分析现有消隐方法及三维有限元网格划分特点的基础上,提出了一种将外法线法与线面比较法相结合的消隐方法──逐步消隐法,快速有效地实现了三维网格的可视化。结果表明,用于三维有限元网格划分的消隐是简便实用的。     

Resource reusing selection scheme for device-to-device communication underlaying LTE-A networks

Device-to-Device (D2D) communication underlaying LTE-A cellular networks is effective to improving spectral efficiency and offload traffic of the base station by reusing cellular resources. However, the mutual interference between D2D and cellular communications can degrade the performance of both D2D and cellular users. In this paper, a resource reusing selection scheme based on minimizing power increase is proposed, which enables selective compensation for signal to interference plus noise ratio (SINR) diminution caused by interference. Simulation results demonstrate that the proposed scheme notably improves the access grant probability of D2D users and increases the link spectral efficiency of D2D and cellular networks, without sacrificing the quality of cellular and D2D communication.     

三维模型拟合二维剖面数据反演调研

野外CSAMT大多采集的是二维剖面数据,如何利用这些二维剖面数据获得尽可能接近实际情况的地电断面是许多电磁学者关心的问题。在对电磁正反演充分调研的基础上,可以对二维CSAMT剖面数据进行三维模型的模拟反演,通过三维数值模拟解决人工场源的三维特征问题,保证对三维地质体的模拟,同时拟合二维剖面数据,减小野外施工难度。在充分调研的基础上,系统地介绍了电磁正反演的研究现状及发展方向,讨论了用三维模型拟合二维剖面数据反演的可行性。     

利用8098单片机的HSO实现多路D/A转换

本文针对利用8098单片机的HSO产生PWM信号实现多路D/A转换时经常出现的中断混乱问题,提出了一个简单实用的改进方案,本方案可以避免中断混乱的产生,顺利地实现多路的D/A转换。     

A/D、D/A转换器的自动化测试

从简化Ａ／Ｄ、Ｄ／Ａ器件测试,构建简单可靠,通用性好的自动测试系统出发,提出了一种软硬件相结合的测试方法,给出了实现原理图,并详细地描述了软件实现过程。该系统可用于制作中低频多功能仪器。     

电力物联网中节能的免许可D2D接入算法设计

针对免许可频段的终端到终端（D2D）通信的功耗问题,进行功率和频谱的联合分配,以寻找使系统终端功耗最小的资源分配方式. 在免许可频段为D2D提出信道接入协议,该协议在许可信道的协助下确定D2D终端可使用的免许可信道及对应信道可使用的时隙资源. 建立以最小化系统总功耗为目标的优化问题,考虑D2D用户对的数据速率和对基站（BS）产生的干扰的限制. 该问题被建模为凸优化问题,利用内点法求解. 通过数值仿真,对免许可频段的D2D通信（D2D-U）的工作情况进行验证,证明利用该算法能够得到最优的分配结果.     

同构零件的三维参数化系统的开发

提出了一种同构零件的三维参数化设计方法。这种方法从基于Solidworks开发的零件库中依据编码查找出同构零件,直接从数据库中调用参数生成新零件,能有效地避免重复工作。新零件可以在三维环境中进行模拟装配和机械运动实验,可进一步检验设计合理性,为改进设计提供依据。     

Estimation of access failure probability in D2D underlaid cellular networks

Device-to-Device (D2D) communication can reduce the mobile devices' energy consumption and increase the spectral efficiency in D2D underlaid cellular networks. However, D2D users will interfere with co-channel cellular users, which can lead to cellular communication access failures. There are two reasons for cellular communication access failures: (1)D2D interference and (2)insufficient spectrum resources. To address the absence of research on the performance of cellular services' access in D2D underlaid cellular networks, this paper defines the new services' access failure probability and handoff services' access failure probability to evaluate the effect of both D2D interference and limited resources on cellular communication access. Based on the stochastic geometry and stochastic process, a random network model is presented to estimate the access failure probabilities, which can provide guidelines for network design to ensure cellular services' access. The accuracy of the estimated access failure probability is validated through extensive simulations.