Sum-rate maximization for UAV-enabled two-way relay systems

In this paper, an Unmanned Aerial Vehicle (UAV)-enabled two-way relay system with Physical-layer Network Coding (PNC) protocol is considered. A rotary-wing UAV is applied as a mobile relay to assist two ground terminals for information interaction. Our goal is to maximize the sum-rate of the two-way relay system subject to mobility constraints, propulsion power consumption constraints, and transmit power constraints. The formulated problem is not easy to solve directly because it is a mixed integer non-convex optimization problem. Therefore, we decompose it into three sub-problems, and use the mutation arithmetic of the Genetic Algorithm (GA) and Successive Convex Approximation (SCA) to dispose. Besides, a high-efficiency iterative algorithm is proposed to obtain a locally optimal solution by jointly optimizing the time slot pairing, the transmit power allocation, and the UAV trajectory design. Numerical results demonstrate that the proposed design achieves significant gains over the benchmark designs.     

Sum-rate maximization in MIMO NOMA system with imperfect CSI

In order to solve the problem of maximizing the sum rate under the constraints of transmission power limitation and users’ rates requirements,precoder and receiver were devised by combining multiple-input multiple-output (MIMO) and non-orthogonal multiple access (NOMA) based on imperfect channel state information (CSI).To take advantage of successive interference cancellation (SIC) techniques to eliminate interference from weak user’s signal,each data stream of the strong user needed to decode the corresponding weak user’s signal.Since the problem formed was non-convex,it was converted into the problem with the difference of two convex functions (D.C.) by using semi-positive definite programming and first-order Taylor expansion,and a penalty function was used to solve the constraint of the rank of the precoding covariance matrix.The simulation results show that compared with the orthogonal multiple access technology,the proposed D.C.algorithm can improve system sum rate.     

FSAE无线数据采集系统

本系统由32位MCU为主控制器,通过CAN总线、AD转换、输入捕获以及集成传感器等方式对赛车各动态数据进行采集记录并通过无线发送到电脑端显示分析.该系统通过CAN总线获得Motec M84采集的传感器数据,并可另外采集10路模拟量、4路脉冲采集,GPS信息采集,6轴传感器采集并支持4路PWM、4路IO控制和提供高达5V3A的电源输出.     

无线供能网络中数据收集的能量效率最大化方案

研究提出由多个射频能量源和汇聚节点组成的无线供能网络,通过联合最优化能量源的发送功率、能量发送时长和节点的数据发送时间,最大化数据收集的能量效率。首先对能量效率最大化问题进行建模。接着,分析得到发送功率的最优取值,并进一步推导出能量效率函数的单调性和吞吐量函数的凹凸性。最后,基于这些属性设计出联合使用黄金分割法和二分法的高效最优算法的快速得到最优解。仿真结果表明,相比于基准方法,所提出的最优算法能显著提高能量效率。     

An efficient data rate maximization algorithm for OFDM based wireless networks

In this paper we present a computationally efficient, suboptimal integer bit allocation algorithm that maximizes the overall data rate in multiuser orthogonal frequency division multiplexing (OFDM) systems implemented in wireless networks. Assuming the complete knowledge of a channel and allowing a subchannel to be simultaneously shared by multiple users we have solved this data rate maximization problem in two steps. The first step provides subchannel assignment to users considering the users’ requests on quality of service (QoS) expressed as the minimum signal-to-noise ratio (SNR) on each subchannel. The second step provides transmit power and bit allocation to subchannels in order to maximize the overall data rate. To reduce computational complexity of the problem we propose a simple method which assigns subchannels to users and distributes power and bits among them. We have analyzed the performance of our proposed algorithm by simulation in a multiuser frequency selective fading environment for various signal-to-noise ratios and various numbers of users in the system. We have concluded that our algorithm, unlike other similar algorithms, is suitable for OFDM wireless networks, especially when signal-to-noise ratio in the channel is low. Also, the results have shown that the total data rate grows with the number of users in the system.     

On subsurface wireless data acquisition system

Measurement, evaluation, and monitoring of subsurface objects often require wireless data transmission between an embedded sensor and an exterior host system. Such technologies find applications in many areas-medical imaging, space exploration, earth formation evaluation in oilfield industries, for example. This paper describes a complete wireless data acquisition system that includes design of a transceiver unit, as well as communication protocols for data encoding and decoding. Although the application considered in this paper pertains to the oilfield industry, the method is applicable to other areas as well. The transceiver design is highly constrained due to requirements on physical size, mechanical stability, and low-power consumption. The host antenna generally consists of ferrite-backed coils wound on a metallic cylinder. A critical requirement in the design of these coils is to produce a desired spatial variation of the magnetic field in a specified region. A genetic algorithm is used to optimize the location and excitation of each coil. A combination of finite-element method and superposition principle is used to speed up the solution of forward problem. The data measured by an embedded sensor are encoded with seven-bit cyclic redundancy code concatenated with Manchester code for error detection/correction and bit synchronization. Coded data are finally transmitted by binary frequency-shift keying modulation scheme. Numerical and experimental results for magnetic field, signal-to-noise ratio, and data demodulation are presented.     

MiniTE: data acquisition routing for wireless sensor networks

Routing is one of the most important supporting parts in wireless sensor networks (WSNs) application that directly affects the application efficiency. Routing time and energy consumption are two major factors used to evaluate WSNs routing. This article proposes a minimum routing time and energy consumption (MiniTE) routing, which can ensure feasibility of the routing protocol both in routing time and energy consumption. Based on the MiniTE, WSNs can be partitioned into different regions according to the received signal strength indication (RSSI). Messages are sent by nodes in the region to their parent node and again up to their parent node until finally to the sink node. Theoretic evaluation and simulation results are given to verify the features of the protocol.     

无线同步数据采集系统设计

设计了以微控制器为核心的数据采集子系统,利用GPS接收模块实现子系统的定位,应用GPS模块的PPS输出信号实现数据采集系统的同步采集,选择XBee-Pro（2．4GHz）无线传输模块实现数据的远距离传输,数据采集子系统的参数可以实现在线配置。通过野外试验验证,采集系统实现了子系统的定位,数据的同步采集,可靠通信距离达到1600米。该系统可方便代替远距离有线数据采集,具有较好的应用前景。     

数据采集及无线收发系统没计

介绍了一种简单的数据采集以及无线收发系统.该系统组成简单,使用方便,可以及时反馈实验测试结果,并且通过远程分析软件,对实验数据进行分析.该系统的主要特点是采用内部集成高精度ADC的1 ADuC841单片机作为主控芯片,通过数据传输单元DTU,利用现有通信网络GPRS,将数据发送到网络上指定的服务器,实现数据的无线收发....     

基于ZigBee的健身数据无线采集系统

文中设计是基于Zig Bee无线传感器网络技术,面向健身俱乐部开发的健身数据无线采集系统。系统主要由佩戴于每个健身会员腕部的无线采集节点、数据采集汇聚节点、计算机等组成,通过人体随身携带的无线终端实时采集运动者的体温与脉搏数据,所有节点与汇聚节点共同组成一个无线传感器网络,汇聚节点与计算机通过串口进行通信,节点采集的参数通过汇聚节点实时传递到计算机上位机程序中。通过文中系统可以实现健身会员的信息管理及健身参数的实时采集,并根据记录数据进行运动效果评价。适用于无线数据采集、健身者运动量分析评价以及长期的健康监测。     

无线数据采集时间同步协议研究与工程应用

无线通信技术给工程地质勘探带来便利的同时,也造成了各采集通道之间的时间同步难题,为此,采用nRF系列无线收发芯片组建工程地质勘探无线数据采集网络,并研究了无线同步协议。重点分析了无线时间同步误差来源,提出了提高时间同步精度的措施,并详细描述了配套的系统硬件、软件组成与实现方法,通过某地质调查项目实际工程应用对系统进行了检验。结果表明,实现了500 m近距离无误码无线数据采集,时间同步误差控制在2μs以内,同时提高了工作效率,工作时间缩短到有线方式的1/3。     

ZigBee无线温度数据采集系统设计

在传统的模拟信号远距离温度测量系统中,需要很好地解决引线误差补偿问题、多点测量切换误差问题和放大电路零点漂移误差问题等技术问题,才能达到较高的测量精度。另外一般监控现场的电磁环境都非常恶劣,各种干扰信号较强,模拟温度信号容易受到干扰而产生测量误差,影响测量精度。因此,在温度采集系统中,采用抗干扰能力强的新型数字传感器和新兴的ZigBee无线传输技术相结合的方案是解决这些问题的最有效方案,新型数字温度传感器DS18B20具有体积更小、精度更高、适用电压更宽、采用一总线、可组网等优点,在实际应用中得到了良好的测温效果,另外通过为系统添加新的测量手段,无线技术能够帮助其改进流程。     

Lifetime maximization for multicasting in energy-constrained wireless networks

We consider the problem of maximizing the lifetime of a given multicast connection in a wireless network of energy-constrained (e.g., battery-operated) nodes, by choosing ideal transmission power levels for the nodes relaying the connection. We distinguish between two basic operating modes: In a static power assignment, the power levels of the nodes are set at the beginning and remain unchanged until the nodes are depleted of energy. In a dynamic power schedule, the powers can be adjusted during operation. We show that while lifetime-maximizing static power assignments can be found in polynomial time, for dynamic schedules the problem becomes NP-hard. We introduce two approximation heuristics for the dynamic case, and experimentally verify that the lifetime of a dynamically adjusted multicast connection can be made several times longer than what can be achieved by the best possible static assignment.     

Energy-efficient and reliable data delivery in wireless sensor networks

Clustering has been used as one of energy-efficient mechanisms for data routing in wireless sensor networks. In hierarchical routing approaches, cluster heads are responsible for management (e.g. data aggregation, queries dispatch) and transmission of the collected data in the region controlled by them. For efficient data delivery, several researches have proposed various mechanisms for cluster organization and cluster head selection. However, less focus is given in the area of data transmission associated with Base Station (BS). In such a situation, any failure or packet loss may lead to considerable packet loss. For solving this problem, we propose an efficient data routing scheme for controlling data delivery from nodes to BS. In our proposed approach every node is aware about the link quality of all nodes and is able to deliver data to the BS through the most reliable and energy-efficient route.     

基于WiFi的无线数据采集系统设计

本设计采用Wi Fi技术进行数据和命令的双向传输。其主要包括数据采集控制器、路由器和上位机。控制器选用51系列单片机,通过各种接口与传感器和执行机构相连,完成多种环境参数采集与显示,同时可以通过键盘设定和查询参数。多个数据采集控制器与路由器相连,作为上位机的电脑或手机也与之相连。这样构成了一个多点无线数据采集及传输系统,可用于智能温室、医院病房等场所,无须布线、施工成本低、终端可以移动。     

物联网智能无线节点自动监控数据采集系统设计

在物联网环境下进行无线节点自动监控数据采集,提高数据检测和诊断分析能力,提出基于动态增益控制和DSP高速信号处理的物联网智能无线节点自动监控数据采集系统设计方法。基于微机总线技术进行无线节点自动监控数据采集系统的总体设计,系统主要包括DSP处理器和PCI总线两大功能模块设计,数据采集的传感器基阵由多传感信息融合的无线监测节点组成,设计收发转换电路和功率放大电路实现采集数据的信号放大和数/模转换。采用动态增益控制方法实现采集数据的放大和滤波处理,基于DSP信号处理器进行自动监控数据采集系统的集成设计。测试结果表明,采用该系统进行物联网智能无线节点自动监控数据采集,能实现持续的大于15 MB/s的实时数据采集和记录,总线持续数据传输速率超过20 MB/s,峰值传输速率也可超过33 MB/s,满足实时记录无线节点自动监控数据的需求。     

Adaptive delivery of video data over wireless and mobile environments

We present an architecture for the adaptable delivery of video data under variable connection characteristics and into devices of variable capabilities. The main application of the proposed architecture is video delivery in wireless and mobile environments. The architecture is based on the Universal Multimedia Access concept and the MPEG‐7 standard. Based on the network and the mobile device, as well as constraints imposed by user preferences and the multimedia content, video is delivered through a careful application of a combination of off‐line and on‐line reductions to the video stream. We present our architecture and describe an implementation of a system based on the architecture. We present basic performance evaluation results to quantify the merit of our approach. Copyright © 2002 John Wiley & Sons, Ltd.     

基于ZigBee的油井无线数据采集系统的设计

针对当代油田井口数据采集困难以及现场监测工作困难的现状,应用ZigBee技术设计了一个无线传感器网络系统来实现对油田数据的采集,以及对油田实时监控管理。其中无线传感器选用JN5139芯片作为主控芯片来设计网络中的协调器与终端节点,并且编写了芯片相应的控制程序。经过网络节点测试,系统满足灵敏度设计要求。     

基于ZigBee的无线数据采集系统的设计

以C8051F020和射频芯片CC2430为核心设计了低功耗的无线数据采集系统,介绍了ZigBee技术,并给出了基于ZigBee的无线数据采集系统的组成.最后通过使用CC2430芯片完成了采集节点,主控单元的硬件与软件设计,实现了数据的采集和无线传输.