基于FPGA的跳频通信系统开发

为了提高通信的抗干扰和保密性,对跳频通信进行了研究,通过分析跳频通信的实现方式,提出基于FPGA的跳频通信系统实现方案。该方案中发端信号采用QPSK调制,接收端采用超外差接收以达到减少噪声和提高接收灵敏度的效果,接收端跳频同步采用等待自同步的跳频捕获和基于延迟锁相环的跳频跟踪。测试结果表明所设计的跳频通信系统可以正确实现跳频通信。与传统跳频通信实现方案相比,该方案具有灵活性强、开发周期短、开发费用低等优点。     

跳频通信系统脉冲同步干扰仿真研究

跳频技术是目前通信领域应用非常广泛的一种通信方式。当跳速足够高、跳频带宽足够宽时,常规的干扰方法往往难以奏效。提出利用脉冲干扰信号对跳频信号的同步部分进行干扰的方法,并在MATLAB中建立典型跳频通信系统的信号级干扰仿真系统,采用脉冲信号进行干扰仿真研究。结果表明,脉冲干扰信号是一种对抗跳频通信的可行方式,针对跳频通信系统的同步部分进行干扰可以有效降低对脉冲信号源的综合指标要求。     

基于光纤布拉格光栅编解码器的直接序列扩频跳频光码分多址系统

提出了一种混合直扩跳频光纤码分多址（DS／FH－OCDMA）系统的实现方法，该系统采用跳频素数码作为扩频码，运用了光纤布拉格光栅序列作为编解码器，并在解码器两端安置了双硬限幅器以提高系统的性能，理论分析和仿真结果表明，该系统具有大用户容量，高功率效率和低误码率等方面的优点。     

LTE宽带无线通信系统在探测器网络中的应用

为提高探测器网络的数据传输能力,适应其网络化、协同化的工作方式,采用基于LTE标准的宽带无线通信系统来构建高速信息链路;为验证LTE宽带无线通信系统的传输能力,分别进行了内场和外场测试;测试结果表明,通过合理选择部署地点,该通信系统满足现有探测器网络更高数据传输容量和更低差错率的要求,同时实现了对通信资源的高效合理利用;LTE宽带无线通信系统具有数据速率高、设备精简、易于快速展开等优点,最后对LTE在专网中的应用前景作了展望。     

一种异步非正交跳频网台盲分选方法

提出了一种新体制跳频网台盲分选方法,针对跳频通信异步非正交组网方式,将基于最大信噪比算法的盲源分离技术应用于跳频网台分选。建立了跳频网台盲分选仿真数学模型并进行了多跳频网台分选仿真。仿真结果验证了盲源分离技术应用在跳频网台分选中的可行性和有效性,得出了跳频网台盲分选方法对异步非正交组网方式的分选性能。     

基于水声传感器网络的多路径协同多跳通信研究

针对水声网络高误码、大时延的特点,借鉴提出了一种多路径协同多跳通信协议,该协议通过多路径、多节点的协同多跳中继通信以及冗余判决,来完成网络中端对端的远程数据传输。通过数值仿真试验分析表明:与普通的点对点直接通信和单路径多跳中继通信方式相比,此协议具有低误码、高能效的特点(距离与能量相同时,误码率低一至两数量级;限定误码率时,每比特能耗降低一个数量级),能够减少数据重发几率,提高网络的通信效率和工作寿命,特别适于水声传感器网络应用。     

基于非参数方法的频率密度分布计算及其并行优化

跳频序列预测是信息对抗的关键问题之一。基于跳频序列具有的伪随机特性和数据之间连续分布的相似性,采用非参数密度估计方法计算并预测出频率的大概率分布区间,进而用于引导通信的梳状灵巧干扰。针对实际应用对实时性的要求,在多结点多核平台上实现了基于消息传递机制的可扩展计算。测试表明,并行程序计算结果正确,并且具有较好的可扩展性。     

基于ARM920T的嵌入式远程及时通信系统设计

目前随着交通复杂程度的不断增大,当前的交通通信系统无法满足车辆间远程、及时通信的要求,降低了行车安全性。为此,设计一种基于基于ARM920T的嵌入式远程及时通信系统,介绍了系统需实现的功能,以ARM920T芯片为核心,利用通信管理机完成数据交换,结合嵌入式系统平台完成系统硬件设计。基于ARM920T的车辆通信子系统通过车辆通信对车辆的行驶进行及时的路线跟踪、碰撞提醒,状态监测以及历史轨迹显示回放。对通信子系统进行设计,子系统分别为车辆定位系统以及车辆调度系统,构建车辆通信模型,进一步实现车辆精准远程通信,并结合蚁群算法对车辆通信模型进行求解。实验结果表明,所设计通信系统不仅通信精度高,而且成本较低,实时性优。     

光纤色度色散对快跳频光码分多址系统性能影响

利用仿真法研究光纤色度色散对快跳频光码分多址系统的影响,主要研究了光纤色散导致的码字自相关输出峰值、取样切普内光能量的减小、不同条件下所能达到的最大用户数据速率和最大传输距离.给出了几个具有不同q值的典型快跳频光码分多址系统的最大用户数据速率和传输距离.提出了减小q值以降低色散影响的码字优化法.讨论了该系统的应用场合问题.     

基于ARM和nRF905组网的智能家居系统设计

针对家居中电器种类和数目繁多且分散于各室造成控制不便,提出了一种利用nRF905射频模块实现无线通信的智能家居控制系统。系统对射频数据传输协议进行了设计,给出了室内多个微控制器的组网方案。用户通过手机短信或万能遥控器把对家电的控制信号发送至基于ARM平台搭建的主控中心,再由主控中心发送至若干个通信节点或智能插座,万能遥控器通过射频信号实现对家电的近距离遥控,手机通过GSM通信实现对家电的远程遥控。通信节点基于STC89C52RC单片机设计,能够实现对多种红外家电的控制并具备安防报警功能,智能插座则用于控制非遥控家电。实验表明,该系统可使网络中各节点、插座得到有效的控制,数据传输稳定、功能丰富、可扩展性强,具备较高的应用价值。     

Colloidal,Functional, Piezoelectric BaTiO3-Au Nanohybrid for Wireless Cell Therapy

Ultrasound-assisted reactive oxygen species (ROS) generation from piezoelectric nanomaterial offers unique wireless therapeutic approach in remote places. In the previous work, piezoelectric barium titanate (BaTiO₃) nanorod have been synthesized and used for wireless cell therapy. However, the piezoelectric property of BaTiO₃ nanorod needs further improvement for diverse applications. In this work, it is shown that gold nanoparticle conjugation with BaTiO₃ nanorod (BaTiO₃-Au) can significantly enhance the piezoelectric performance with the piezoelectric constant value of 110 pm V⁻¹. The colloidal BaTiO₃-Au is further functionalized with folate for selective targeting of folate-overexpressed cancer cells and used for wireless cell therapy via intracellular ROS generation under ultrasound exposure. The synthesized colloidal nanohybrid can be used for various therapeutic applications.     

Analysis of scalability for AODV routing protocol in wireless sensor networks

This paper presents preliminary work to address scalability concern over AODV protocol in wireless sensor network. Firstly, we discussed the scalability design issues with related work in context of wireless sensor networks (WSN). Following, we designed and illustrated wireless sensor network model. Finally, significance of scalability on the behaviour of application, MAC, transport and physical layer performance is described.     

Quantum-correlation-based free-space optical link with an active reflector

We present a quantum-correlation-based free-space optical(FSO) link over 250 m using an outdoor active reflector 125 m from the transceiver station. The performance of free-space optical communication can be significantly degraded by atmospheric turbulence effects, such as beam wander and signal fluctuations. We used a 660 nm tracking laser to reduce atmospheric effects, by analyzing the fast beam wander and slow temporal beam drift, using this information to correct the quantum channel alignment of the 810 nm signal photons. In this work, the active reflector consisted of a mirror, a 6-axis hexapod stage, and a long-range wireless bridge. The slow drift of the beam path due to outdoor temperature changes was steered and controlled using wireless optical feedback between the receiver units and the active reflector. Our work provides useful knowledge for improved control of beam paths in outdoor conditions, which can be developed to ensure high quality quantum information transfer in real-world scenarios, such as an unmanned FSO link for urban quantum communication or retro-reflective quantum communication links.     

西安理工大学无线光通信系统自适应光学技术研究进展

总结了国内外自适应光学技术在无线光通信系统应用中的研究进展和技术分类,同时介绍了西安理工大学在该领域的工作,包括有波前测量的自适应光学系统、无波前测量的自适应光学系统、液晶空间光调制器波前校正、偏摆镜和变形镜组合的波前校正、空间光光纤耦合自适应光学波前校正等。自适应光学技术可有效修正无线光通信系统中由大气湍流引起的畸变波前,提高耦合效率和通信性能。虽然这些方法在理论分析和工程实际中尚不完善,但不失为人们在该领域进行的有益探索。     

Optical design for an LED-based handheld underwater wireless optical communication system

We propose an LED reshaping lens design for a handheld underwater wireless optical system to solve the problem of targeting the receiver. The simulation results shows that the designed lens can achieve 0.91 light intensity uniformity and 91.39% optical efficiency in hemisphere space, even with the actual LED model. After fabrication with computer numeric control, the work demonstrates the design to be effective.     

Minority game for cognitive radios: Cooperating without cooperation

In this paper we report on our preliminary results and recent work on building cognitive wireless networks that achieve resource sharing in a local environment. We emphasize two major issues. First, the cross-layer optimization at the network level requires exchange of information between OSI-layers in the terminal and often among the nodes that form the network. Second, the cooperative behavior among the radios is often believed to require a rich exchange of information. We show in this paper that cooperation can be an emergent phenomenon without any complex signalling. We apply Minority Games to cognitive wireless networks to show that resource sharing can be achieved without detailed information exchange or coordination between strategies. We further argue that Minority Games are not only a useful analysis tool, but a potentially efficient method to develop actual resource sharing algorithms. We conclude the paper by pointing out that also other swarm intelligence type of solutions could be applied to cognitive radio communications.     

双基地混响平均强度理论及仿真预报

考察远程双基地界面混响,可以仅考察二维问题,其散射区域为一椭圆环带;对于近程双基地界面混响,必须讨论三维模型,其散射元分布在一椭球面上.对二维和三维双基地混响进行理论建模分析,该模型优点是无需使用无线电通信,借助GPS时钟即可同步工作,实现双基地声呐系统的测距及测向,便于双基地声呐系统的集成.推导出二维和三维模型的双基地声压混响理论预报公式.对三维矢量混响作仿真研究,并讨论矢量传感器组合指向性抗混响. 关键词： 双基地混响 声压混响 矢量混响     

Spatial networks with wireless applications

Many networks have nodes located in physical space, with links more common between closely spaced pairs of nodes. For example, the nodes could be wireless devices and links communication channels in a wireless mesh network. We describe recent work involving such networks, considering effects due to the geometry (convex, non-convex, and fractal), node distribution, distance-dependent link probability, mobility, directivity, and interference.     

物联网云平台ZigBee无线通信网络节点设计

随着科学技术的发展,无线通信技术不断成为当今社会的通信方面的主流发展方向;对于一种可以集所有通讯方式的优点为一体,并且可以实现远距离网络通信传输的方式成为现在通讯技术行业的主要研究方向;而文章根据一种基于ZigBee协议的无线网络通信架构进行研究,设计出一种可以满足当今通信需求的硬件平台;其中应用到ZigBee协议中的短距离传输技术和将其与SPI接口连接完成的一种通信技术手段;最后将ZigBee单片机通过USB接口与计算机相连接完成通信无线传输工作;文章中提出了这种平台设计的软件设计方案和硬件设计方案,并且通过软硬件设计,分析出其所具备的优点和未来发展能力;通过对比试验,得出这种无线传播方式有更好的传播效率和节省能源的优势。     

An overview of simultaneous wireless information and power transfer in massive MIMO networks: A resource allocation perspective

Providing a stable and perpetual source of energy to charge battery-powered wireless communication devices is viewed as a major challenge in wireless communication systems. This challenge leads to the trending research area where radio frequency signals are being exploited for energy harvesting purposes. The technique for achieving this is known as simultaneous wireless information and power transfer (SWIPT). In recent studies on SWIPT, the massive Multiple-Input-Multiple-Output (MIMO) aided energy harvesting has attracted considerable attention from the research community. This can be attributed to the high energy delivery rate of massive MIMO antenna systems due to their capacity to focus transmitted signals in the direction of the intended receivers. However, SWIPT in massive MIMO networks requires an optimal design to achieve a proper balance between different conflicting network objectives. In this article, we aim to discuss various contributions to SWIPT in massive MIMO networks in order to address critical design issues. In particular, we focus on the widely adopted approach to resolving SWIPT-related issues in massive MIMO networks, that is, the resource allocation design. We also extend our discussion to studies dedicated to solving critical design challenges. In this regard, we take into consideration the energy efficiency and security aspect of the system design. Finally, we identify potential areas that can be explored for future research work.