基于无线感知辅助的车联网下行无线资源分配方法

在车联网（vehicle-to-everything，V2X）中，感知与安全类数据的高速下发与共享对道路交通安全至关重要。然而，车辆高速移动所引起的通信链路不稳定，会导致现有的基于车辆位置信息上报的通信资源分配方法不再高效。为此，提出了一种基于通信节点无线感知辅助的车联网下行无线资源分配方法。首先，构建了通信与感知资源正交下的通信模式选择与无线资源分配联合优化问题；之后，为解决这一问题提出了基于Delaunay三角划分的分簇通信模式选择与基于改进图着色的资源分配策略，以实现下行吞吐量的提升；最后，仿真分析了无线感知估计误差、车辆数量对算法性能的影响。仿真结果表明，与传统方法相比，所提算法在相同感知带宽资源占比下可获得更好的下行通信性能增益，并能够承受更大的感知误差对性能的影响，同时，所提算法的计算复杂度较低，可节省网络算力资源。     

A software support infrastructure for wireless access routers

Routers are expected to play an important role in the Internet protocol-based wireless data network. Although a substantial number of adaptive and intercell coordination techniques have been proposed to improve wireless network performance under dynamic wireless channel conditions and host mobility, a system support framework is still missing. In this paper, we describe DIRAC, a software-based router system that is designed for wireless networks to facilitate the implementation and evaluation of various channel-adaptive and mobility-aware protocols. DIRAC adopts a distributed architecture that is composed of two parts: a router core (RC) shared by the wireless subnets, and a router agent (RA) at each access point/base station. RAs expose wireless link-layer information to the RC and enforce the control commands issued by the RC. This approach allows the router to make adaptive decisions based on link-layer information feedback on both data and control planes. It also permits the router to enforce its policies (e.g., policing) more effectively through underlying link-layer mechanisms. It further enables interaccess-point coordination at the RC. As showcases, we implement under DIRAC the prototypes of three wireless network services: link-layer assisted fast handover, channel-adaptive scheduling, and link-layer enforced policing. Our implementation and experiments show that our distributed wireless router provides a flexible framework, which enables advanced network-layer wireless services that are adaptive to channel conditions and host mobility.     

Capacity of wireless erasure networks

In this paper, a special class of wireless networks, called wireless erasure networks, is considered. In these networks, each node is connected to a set of nodes by possibly correlated erasure channels. The network model incorporates the broadcast nature of the wireless environment by requiring each node to send the same signal on all outgoing channels. However, we assume there is no interference in reception. Such models are therefore appropriate for wireless networks where all information transmission is packetized and where some mechanism for interference avoidance is already built in. This paper looks at multicast problems over these networks. The capacity under the assumption that erasure locations on all the links of the network are provided to the destinations is obtained. It turns out that the capacity region has a nice max-flow min-cut interpretation. The definition of cut-capacity in these networks incorporates the broadcast property of the wireless medium. It is further shown that linear coding at nodes in the network suffices to achieve the capacity region. Finally, the performance of different coding schemes in these networks when no side information is available to the destinations is analyzed.     

激光无线能量传输接收系统二次聚光研究

为了克服激光无线能量传输接收系统中聚焦光斑能量分布不均匀、光斑形状不匹配的缺陷,设计并加工了一种梯形二次聚光器。依据边缘光线理论分析了梯形二次激光器的设计原理,利用Tracepro软件进行了仿真,采用直角梯形拼接的方法加工成梯形二次聚光器。在激光无线传能系统中对梯形二次聚光器进行了实验研究,对比了菲涅耳透镜单次聚光和与梯形二次聚光器组合聚光时对激光电池效率的影响。实验得出,在激光电池接收功率一致的情况下,菲涅耳透镜与梯形二次聚光器组合产生的聚焦光斑能使激光电池的转换效率值提高6%~7%;在计入二次聚光器损耗后,激光电池的转换效率值提高2%~3%。结果表明:梯形二次聚光器的使用可以提升激光无线传能系统接收端的性能。     

无线传感器网络节点应用的硬件设计

针对无线传感器网络技术引入到矿下安全监测中,首先分析了无线传感器网络的结构、特点及研究重点,提出了无线传感器网络节点的整体设计方案.介绍了传感器的选择和处理器、通信器件的选择,并将硬件分为数据采集单元、数据处理单元和数据传输单元进行详细的说明.     

Throughput-range tradeoff of wireless mesh backhaul networks

Wireless backhaul communication is expected to play a significant role in providing the necessary backhaul resources for future high-rate wireless networks. Mesh networking, in which information is routed from source to destination over multiple wireless links, has potential advantages over traditional single-hop networking, especially for backhaul communication. We develop a linear programming framework for determining optimum routing and scheduling of flows that maximizes throughput in a wireless mesh network and accounts for the effect of interference and variable-rate transmission. We then apply this framework to examine the throughput and range capabilities for providing wireless backhaul to a hexagonal grid of base stations, for both single-hop and multihop transmissions for various network scenarios. We then discuss the application of mesh networking for load balancing of wired backhaul traffic under unequal access traffic conditions. Numerical results show a significant benefit for mesh networking under unbalanced loading.     

移动IP在无线局域网下的一种快速切换方法

针对移动IP在无线局域网下的应用,提出了一种新的基于链路层的移动IP快速切换方法,通过在无线局域网的无线接入点间加入特定的MAC网桥来减少移动节点在切换时产生的切换时延,进而减少移动节点上行和下行方向上的数据包的丢失,达到对移动IP切换进行优化的目的。此方法在无线局域网实际环境中进行了性能测试,结果证明优化后的时延较之原来普通移动IP切换时延有明显降低。     

Bandwidth-efficient wireless multimedia communications

Commencing with a brief history of mobile communications and the portrayal of the basic concept of wireless multimedia communications, the implications of Shannon's theorems regarding joint source and channel coding for wireless communications are addressed. Following a brief introduction to speech, video, and graphical source coding as well as the cellular concept, a rudimentary overview of flexible, reconfigurable, mobile radio schemes is provided. We then summarize the fundamental concepts of modulation, introduce an adaptive modem scheme, and argue that third-generation transceivers might become adaptively reconfigurable under network control in order to meet backward compatibility requirements with existing systems and to achieve best compromise among a range of conflicting system requirements, complexity and power consumption, robustness against channel errors, etc     

无线传感器网络的神经网络模型

无线传感器网络是复杂的无线网络。无线传感器网络拥有大量的网络节点。网络节点是无线传感器网络的基础。为了研究复杂的无线传感器网络，采用了神经元描述了WSN的网络节点，用神经元模型表示了无线传感器网络。给出了无线待感器网络节点的神经元模型和无线传感器网络的神经网络模型，并将神经网络应用于无线传感器网络的数据融合应用。结果表明，基于神经网络的无线传感器网络研究可以使得复杂研究变得简单，利于开展WSN的深入研究。     

无线网络多网协同下的规划优化

本文首先探究了无线网络规划中多网通信的特点以及无线网络多网协同下规划设计的原则,重点分析了增强多网协同下的无线网络规划优化的措施,以此来降低移动通信的建设成本,提高网络质量与安全.     

一种基于CNN的无线路由器指纹识别方法

针对无线设备"指纹"特征提取技术含量较高，且技术手段较为复杂的问题，在无线空间信道状态不变的前提下，提出了一种基于卷积神经网络（convolution neural network，CNN）自动分类无线路由器指纹的识别方法，解决无线设备"指纹"特征提取困难的问题.文章设计并实现了一种通过接收处理多输入多输出（multiple-input multiple-output，MIMO）信号幅度识别无线路由器的方法，该方法通过采集无线路由器的信道状态信息（channel state information，CSI），并对CSI的幅度数据进行预先平滑和去噪处理，然后把预处理后的幅度数据作为设备的指纹特征，最后通过机器学习的算法进行分类和识别.实验采用CNN对10台商用无线路由器进行分类和识别，准确率达到96%以上，证明了使用CSI来识别无线路由器是可行的.     

双模式可调的无线电能传输

无线电能传输是一种利用近场感应将能量传送的技术。电感耦合型无线电能传输存在一些关键问题有待解决,如：转化效率低,充电过程中产生环境电磁污染等缺点。本论文探索了方波触发下输电转化效率随频率和占空比的变化规律,设计出可调频率、可调占空比的磁共振式无线充电装置,该装置具有电能转化效率最高模式和充电输出功率最大模式双重功能。     

Reliability and lifetime modeling of wireless sensor nodes

The accuracy of system reliability analysis depends not only on system-level model construction, but also on realistic estimation of failure parameters at the component-level. In this paper, we model and evaluate the reliability and lifetime of a wireless sensor node under three typical working scenarios, contributing toward the accurate reliability analysis of wireless sensor network systems. According to the medium access control (MAC) protocols, the three working scenarios are defined based on the sensor node modes (sleep and active) and the mechanism of alternating between the modes. Reliability and lifetime of wireless sensor nodes under these three scenarios are illustrated and compared through numerical examples.     

Multi-ray channel modeling for programmable wireless environments in the terahertz band

Terahertz communication system based on programmable wireless environment allowed programming customization of electromagnetic wave propagation in the most suitable ways for different wireless devices.It could not only improve serious fading,interference and non-line-of-sight problems,but also significantly enhance the security and privacy of the system.The channel modeling of terahertz wireless communication in programmable wireless environment was focused.Firstly,a multi-ray channel model for terahertz-band programmable wireless environment was established based on ray tracing technology as well as the propagation model of line-of-sight and non-line-of-sight.Then,based on the established propagation model,reflection coefficient,the broadband channel capacity under the water-filling power allocation algorithm and the RMS delayed extension were further studied.The simulation and analysis results show that the programmable wireless environment greatly reduces the influence of path loss and multipath fading in terahertz wireless transmission through active interference in electromagnetic wave transmission,improves the transmission capacity of terahertz communication system,which provides a reference for the later design of terahertz communication system,especially indoor terahertz communication system.     

A hybrid network coding technique for single-hop wireless networks

In this paper, we investigate a hybrid network coding technique to be used at a wireless base station (BS) or access point (AP) to increase the throughput efficiency of single-hop wireless networks. Traditionally, to provide reliability, lost packets from different flows (applications) are retransmitted separately, leading to inefficient use of wireless bandwidth. Using the proposed hybrid network coding approach, the BS encodes these lost packets, possibly from different flows together before broadcasting them to all wireless users. In this way, multiple wireless receivers can recover their lost packets simultaneously with a single transmission from the BS. Furthermore, simulations and theoretical analysis showed that when used in conjunction with an appropriate channel coding technique under typical channel conditions, this approach can increase the throughput efficiency up to 3.5 times over the automatic repeat request (ARQ), and up to 1.5 times over the HARQ techniques.     

上下文感知的6G无线网络

ICDT深度融合是移动通信演进的重要技术趋势之一,如何实现无线网络和AI技术的深度融合是无线网络中演进的重要课题。基于内生AI（native AI）概念,研究在无线网络中使用AI工具进行无线资源优化。提出了一种上下文感知的6G无线网络架构,并在RRM中引入内生AI工具,形成智能控制器智能化无线资源管理（AI-driven RRM）,完成智能无线资源管理的控制器,在大数据和人工智能的驱动下,实现对无线资源的智能化管理。该部署方案把智能控制器按照功能进行部署,并支持动态的功能伸缩,让其部署独立于基站接入点之外以实现基站硬件成本最小化。     

Robust resource allocation algorithm for heterogeneous wireless networkwith SWIPT

To improve energy efficiency and robustness of heterogeneous wireless networks with wireless information and power transfer,the robust joint transmit power and power splitting resource allocation problem was studied.Based on mini-max probability machine and Dinkelbach method,the original NP-hard problem was transformed into a solvable convex optimization form,meanwhile a distributed dual resource allocation algorithm was proposed.Additionally,both computational complexity and robust sensitivity were analyzed.Simulation results show that the proposed algorithm can guarantee the quality of service requirements of macro cellular users and femtocell users under channel uncertainties.     

An integrated testbed for wireless multimedia computing

A testbed has been constructed to evaluate node architectures that support multimedia applications and services across a wireless network. Using this testbed, a low bitrate subband video compression algorithm has been prototyped in a field programmable gate array (FPGA) and evaluated for video networking across bandwidth-limited RF channels. A radio interface has been prototyped in an FPGA and a common applications programming interface (API) has been developed to allow experimentation with multiple radios. This testbed has been used to evaluate node performance under two different wireless applications: 1) simultaneous video and data networking (VTALK) and 2) TCP/IP utilities such as FTP and telnet. Based on this evaluation, the design of a battery-operated high throughput wireless multimedia node is presented.     

SDN-based wireless user management system

The degradation of end-to-end quality of service (QoS) on mobile users is becoming a common issue for IEEE 802.11 infrastructure-based networks in crowded areas. This research tackles the issue by employing an SDN framework on an integrated wireless/wired environment. Thereby, we present the development and implementation of a system that performs user management by analyzing the network load from the OpenFlow statistics, as well as the wireless information collected from the associated users. In order to analyse the behaviour of the proposed user migration algorithm, we evaluate the system under scenarios with different traffic load and user session duration. From the experiments, we observed that in several cases wireless users get a considerable QoS improvement at the application layer (up to 30% improvement in throughput and up to 20% in delay in our simulations) once the system is activated. Based on the results, we present an analysis on how and when user migration in multi-access point IEEE 802.11 networks can be most effective.     

Capacity of wireless networks under SINR interference constraints

A fundamental problem in wireless networks is to estimate their throughput capacity—given a set of wireless nodes and a set of connections, what is the maximum rate at which data can be sent on these connections. Most of the research in this direction has focused either on random distributions of points, or has assumed simple graph-based models for wireless interference. In this paper, we study the capacity estimation problem using a realistic Signal to Interference Plus Noise Ratio (SINR) model for interference, on arbitrary wireless networks without any assumptions on node distributions. The problem becomes much more challenging for this setting, because of the non-locality of the SINR model. Recent work by Moscibroda et al. (IEEE INFOCOM 2006, ACM MobiHoc 2006) has shown that the throughput achieved by using SINR models can differ significantly from that obtained by using graph-based models. In this work, we develop polynomial time algorithms to provably approximate the throughput capacity of wireless network under the SINR model.