多音干扰下Nakagami-m信道传输Link16数据链的性能分析

Link16数据链的应用综合广泛,由于运用了跳扩频和编码技术使其具有强大的抗干扰能力。为了探究Link16数据链在衰落信道下的响应,在加性高斯白噪信道的基础之上,研究了Link16数据链经过Nakagami-m衰落信道的系统性能。着重推导了Link16数据链单脉冲结构在多音干扰下经过Nakagami-m衰落信道的误码率(bit error rate,BER)表达式,并给出了双脉冲结构BER公式。仿真实验结果验证了Link16数据链单脉冲结构在多音干扰下经过Nakagami-m衰落信道的BER公式的准确性,分析了多径参数对Link16数据链抗干扰性能的影响,得出增加衰落参数m和可分辨路径可以提升Link16数据链的系统性能,且当信干比一定、被干扰频点个数在25个及以上时系统BER达到10-1。

Shortest Link Scheduling in Wireless Networks with Oblivious Power Control

Link scheduling has always been a fundamental problem in wireless networks for its direct impacts on the performance of wireless networks such as throughput capacity,transmission delay,lifetime,etc.Existing work is mainly established under graphbased models,which are not only impractical but also incorrect due to the essentially fading characteristics of signals.In this paper,we study the shortest link scheduling problem under two more realistic models,namely the signal to interference plus noise ratio(SINR)model and the Rayleigh fading model.We propose a centralized square-based scheduling algorithm(CSSA)with oblivious power control under the SINR model and prove its correctness under both the SINR model and the Rayleigh fading model.Furthermore,we extend CSSA and propose a distributed square-based scheduling algorithm(DSSA).Note that DSSA adopts CSMA/CA so that a wireless node can compete for the wireless channel before starting its communication.We also show theoretical analysis and conduct extensive simulations to exhibit the correctness and efficiency of our algorithms.

On the System Performance of Mobile Edge Computing in an Uplink NOMA WSN With a Multiantenna Access Point Over Nakagami-m Fading

In this paper,we study the system performance of mobile edge computing(MEC)wireless sensor networks(WSNs)using a multiantenna access point(AP)and two sensor clusters based on uplink nonorthogonal multiple access(NOMA).Due to limited computation and energy resources,the cluster heads(CHs)offload their tasks to a multiantenna AP over Nakagami-m fading.We proposed a combination protocol for NOMA-MEC-WSNs in which the AP selects either selection combining(SC)or maximal ratio combining(MRC)and each cluster selects a CH to participate in the communication process by employing the sensor node(SN)selection.We derive the closed-form exact expressions of the successful computation probability(SCP)to evaluate the system performance with the latency and energy consumption constraints of the considered WSN.Numerical results are provided to gain insight into the system performance in terms of the SCP based on system parameters such as the number of AP antennas,number of SNs in each cluster,task length,working frequency,offloading ratio,and transmit power allocation.Furthermore,to determine the optimal resource parameters,i.e.,the offloading ratio,power allocation of the two CHs,and MEC AP resources,we proposed two algorithms to achieve the best system performance.Our approach reveals that the optimal parameters with different schemes significantly improve SCP compared to other similar studies.We use Monte Carlo simulations to confirm the validity of our analysis.

A 16-QAM 45-Gbps 7-m Wireless Link Using InP HEMT LNA and GaAs SBD Mixers at 220-GHz-Band

This paper presents a 220-GHz-band 7-m wireless link with a 45-Gbps transmission data rate by using 16 quadrature amplitude modulation(16-QAM).Super-heterodyne transceiver modules are developed for transmission and reception of the modulated signals,which consist of a Schottky barrier diodes(SBD)based sub-harmonic mixer(SHM),an InP HEMT low noise amplifier(LNA),a waveguide band-pass filter(BPF),and a 108-GHz local oscillator(LO)multiplier chain.The transmitter features a peak transmit power of 1.41 dBm,and the IF frequency varies from 5 GHz to 20 GHz.Besides,the receiver features a conversion gain of 9.3 dB in average and a noise temperature of 3052.8 K.The measured results indicate that the transceiver modules enable data transmission of a 45-Gbps 16-QAM signal with Signal-Noise-Ratio(SNR)from 11.59 dB to 15.36 dB in a 7-m line-of-sight channel.

A Comparison of Link Layer Attacks on Wireless Sensor Networks

Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions such as cost, invisible deployment and many application domains, lead to small size and resource limited sensors [3]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional network security techniques are unusable on WSNs [3];This is due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. Therefore security is a vital requirement for these networks;but we have to design a proper security mechanism that attends to WSN’s constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs’ link layer attacks and a comparison of them. This work enables us to identify the purpose and capabilities of the attackers;furthermore, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paper discusses known approaches of security detection and defensive mechanisms against the link layer attacks;this would enable IT security managers to manage the link layer attacks of WSNs more effectively.

A NOVEL LINK ADAPTATION SCHEME TO ENHANCE PERFORMANCE OF IEEE 802.11G WIRELESS LAN

A novel link adaptation scheme using linear Auto Regressive （AR） model channel estimation algorithm to enhance the performance of auto rate selection mechanism in IEEE 802.11g is proposed. This scheme can overcome the low efficiency caused by time interval between the time when Received Signal Strength （RSS） is measured and the time when rate is selected. The best rate is selected based on data payload length, frame retry count and the estimated RSS, which is estimated from recorded RSSs. Simulation results show that the proposed scheme enhances mean throughput performance up to 7%, in saturation state, and up to 24% in finite load state compared with those non-estimation schemes, performance enhancements in average drop rate and average number of transmission attempts per data frame delivery also validate the effectiveness of the proposed schelne.

经典Link数据链信道传输模型及特性研究

随着生活节奏不断加快,对通信信息的实时接收要求越来越高,需要各类信息能够快速传递,各个工作节点单元信息的共享、协作、同步已经逐渐成为成功与否的关键因素,而实现这一功能的数据链系统整体性能主要取决于其信道传输的性能。文中主要针对数据链技术中信息传输通道的性能进行研究,给出直接影响整个数据链系统性能的因素,并利用OPNET对Link-16数据链进行传输建模,采用无线信道连接的方式,设计了各种数据链通信环境以检验其性能指标,网络中每个节点的调制方式、带宽、码元传输速率、工作频段设置符合经典Link数据链的标准。仿真结果展示了信道传输的平均延时、错误数据、有效数据和接入节点随时间变化的情况,并给出调制方式对数据量丢包率、平均延时等数据链信道传输性能的影响结果,研究结论对数据链应用的发展具有一定的借鉴意义。

Optimizing Storage for Energy Conservation in Tracking Wireless Sensor Network Objects

The amount of needed control messages in wireless sensor networks(WSN)is affected by the storage strategy of detected events.Because broadcasting superfluous control messages consumes excess energy,the network lifespan can be extended if the quantity of control messages is decreased.In this study,an optimized storage technique having low control overhead for tracking the objects in WSN is introduced.The basic concept is to retain observed events in internal memory and preserve the relationship between sensed information and sensor nodes using a novel inexpensive data structure entitled Ordered Binary Linked List(OBLL).Whenever an object passes over the sensor area,the recognizing sensor can immediately produce an OBLL along the object’s route.To retrieve the entire information,the OBLL can be traversed with logarithmic complexity which is much less than the traversing complexity of existing linked list structures.Performance evaluation and simulations were carried out to ensure that the suggested technique minimizes the number of messages and thus saving energy and extending the network life.

Modelling a Learning-Based Dynamic Tree Routing Model for Wireless Mesh Access Networks

Link asymmetry in wireless mesh access networks(WMAN)of Mobile ad-hoc Networks(MANETs)is due mesh routers’transmission range.It is depicted as significant research challenges that pose during the design of network protocol in wireless networks.Based on the extensive review,it is noted that the substantial link percentage is symmetric,i.e.,many links are unidirectional.It is identified that the synchronous acknowledgement reliability is higher than the asynchronous message.Therefore,the process of establishing bidirectional link quality through asynchronous beacons underrates the link reliability of asym-metric links.It paves the way to exploit an investigation on asymmetric links to enhance network functions through link estimation.Here,a novel Learning-based Dynamic Tree routing(LDTR)model is proposed to improve network performance and delay.For the evaluation of delay measures,asymmetric link,interference,probability of transmission failure is evaluated.The proportion of energy consumed is used for monitoring energy conditions based on the total energy capacity.This learning model is a productive way for resolving the routing issues over the network model during uncertainty.The asymmetric path is chosen to achieve exploitation and exploration iteratively.The learning-based Dynamic Tree routing model is utilized to resolve the multi-objective routing problem.Here,the simulation is done with MATLAB 2020a simulation environment and path with energy-efficiency and lesser E2E delay is evaluated and compared with existing approaches like the Dyna-Q-network model(DQN),asymmetric MAC model(AMAC),and cooperative asymmetric MAC model(CAMAC)model.The simulation outcomes demonstrate that the anticipated LDTR model attains superior network performance compared to others.The average energy consump-tion is 250 J,packet energy consumption is 6.5 J,PRR is 50 bits/sec,95%PDR,average delay percentage is 20%.

基于复杂信道服务模型的高效可靠链路控制方法

面向无线通信网络化应用发展趋势,针对无线链路容错概率高、实时变化大、信道带宽窄导致链路可靠控制难的问题,提出了基于复杂信道服务模型的高效可靠链路控制方法;分析了无线传播复杂信道服务模型的多种特点,提出了基于无线信道服务模型紧密耦合高效适配的控制机制,设计了无线链路层自适应分组反馈控制流程,结合帧结构设计给出了数据分组长度、最大重数次数等关键参数演算方法;在物理层最小分组长度对应传输成功率85%~99%条件下,仿真给出最佳分组长度为最小分组的2~9倍,最大重数次数为9次缩减至4次;仿真验证表明:在业务数据包长度为最小分组长度的10~100倍时,相比无链路控制状态,传输成功率由1%~90%改进至99.99%以上,平均吞吐量可提升两倍以上。

基于扇形链路策略的改进蚁群分簇路由协议

针对网络覆盖区域较大、节点数量较多的无线传感器网络,容易出现部分节点过早死亡等情况,提出一种基于扇形链路策略的改进蚁群分簇路由协议RACO-SL。通过加入奖惩因子,同时对精英个体采用蚁群优化算法的概率生成新的后代个体,对于普通个体,通过与随机选择的精英个体进行交叉变异操作,改进蚁群优化算法,以整个网络每次通信的能耗为优化目标选取较优的簇头节点集。为待转发簇头节点设计从可动态调节的扇形区域中选择下一跳中继节点的链路转发策略。实验结果表明,与现有协议相比,该协议在延长网络寿命、提高通信链路质量、增强网络覆盖度方面表现良好。

一种基于动态门限与LMS算法相结合的多径干扰抑制算法

在船舰行驶过程中,信号的传输在岛屿反射与海面散射影响下易产生多径效应,使船舰的无线地空数据接收系统受到影响。为提高接收机的接收性能,首先完成了多径信道的建模,搭建了三径信道模型,并在此模型下,将动态门限法与最小均方(LMS)算法进行改进结合,并用此算法完成了信号处理的研究与仿真。仿真结果表明,所提算法优化方案可以提高在此种情况下信号接收系统的准确性。

基于REPBR跳数效用转发的改进路由算法

针对基于压力的水下无线传感器网络路由协议数据包传输路径距离过长、能量消耗不均衡等问题,提出一种基于REPBR跳数效用转发的改进路由算法。采用一种效用函数策略即加入剩余能量、节点间的跳数和链路质量3种因子解决能量消耗不均衡的问题,引入最小跳数算法获取节点到sink节点的跳数值,在数据包转发阶段综合比较路由效益选择最佳转发节点。仿真结果表明,改进后算法相比REPBR、EEDBR、DBR有较小的网络时延,提升了数据包的转发效率,提高了网络性能。

基于拓扑优化和链路感知的无线体域网路由协议

为解决无线体域网(Wireless Body Area Networks,WBAN)在人体运动过程中网络拓扑结构频繁变化导致链路质量和WBAN性能下降等问题,首先根据人体结构对WBAN网络拓扑进行优化,通过添加中继节点建立WBAN主干网,提供节点和hub之间相对稳定的链接,然后提出了适用于WBAN拓扑优化后的路由策略(Routing Protocol Based on Topology Optimization and Link Awareness,R-TOLA)。R-TOLA综合了链路质量感知和代价函数,通过调整主干网中继和节点中继获得最优化路径。仿真实验表明,基于拓扑结构优化和链路感知的R-TOLA协议和其他路由协议相比,在人体拓扑网络结构频繁变化的环境下具有网络生存时间更长、吞吐量更大等优势。

智能反射面辅助OFDMA云接入网的资源分配方法

本文研究了智能反射面(IRS)辅助OFDMA(Orthogonal Frequency Division Multiple Access,正交频分多址接入)云无线接入网(C-RAN)的下行链路传输系统,其中基带处理单元(BBU)池通过多个远端射频头(RRH)与多个用户进行通信.RRH到用户的接入链路采用OFDMA接入技术.对于BBU池到RRH,采用无线前传链路,并且部署多个IRS以增强链路传输能力.在BBU池和每个RRH发射功率约束下,本文提出通过联合优化前传链路和接入链路资源配置使下行用户和速率最大化.由于该资源配置问题是非凸的,首先采用连续凸逼近(SCA)对目标以及约束条件进行转换.其次,将转换后的问题拆分成三个子问题来交替性求解.最后,计算机仿真结果显示了所提出的联合资源分配方法与其他基准方案相比具有显著的传输性能增益.

TP-LINK新产品扩建企业无线网络的方案

为了解决企业内用户随时随地高质量上网的问题,提出一种用TP-LINK新产品扩建企业无线网络的方案。首先简述了无线局域网IEEE 802.11系列标准和主要设备,然后对某企业环境及其园区有线网络的拓扑结构进行分析,在企业现有有线网络的基础上,采用了基于TPLINK新产品的Fit AP+AC组网技术。实践证明该方案增强了企业网络信号的稳定性、提高了传输速率、增加了覆盖范围和带机量,满足了企业内移动用户高质量的上网要求。

RLINK:一种真实的无线传感器网络链路仿真模型(英文)

在网络仿真中,链路模型的精确性对仿真结果的真实性有着重要影响。基于在无线传感器网络实验中观察到的链路的核心特殊性质——不等向连通性,提出了一个真实的链路仿真模型RLINK.通过对不等向连通性的三个因素进行分析建模,即由遮蔽效应引起的路径衰减的差异、节点硬件的校准差异和天线的方向性差异,该模型实现了无线传感器网络链路的精确模拟。以链路不对称性的累积分布和算数平均值为指标,对比实验和仿真中获得的有关链路特性的统计数据,两者的一致性验证了RLINK的精确性。

基于自整定PID算法的无线通信网络传输链路拥塞控制方法

由于无线通信网络数据量大、拓扑结构复杂,导致传输链路拥塞控制效果差,为实现对链路拥塞现象的有效控制,提出基于自整定比例-积分-微分(PID)算法的无线通信网络传输链路拥塞控制方法。以无线自组网按需平面距离向量路由(AODV)协议作为链路拥塞控制的约束条件,保证传输链路中数据的调度格式。利用线性PID控制器设计无线通信网络传输链路拥塞控制器,灵活适应不同的拥塞控制需求。针对线性PID控制器参数设置精度较差的问题,引入自整定PID算法,通过计算占空比与阈值比对,得出传输链路拥塞状态的检测与预测结果。考虑链路容量计算拥塞控制量并反馈至自整定PID算法拥塞控制器,通过慢启动、拥塞避免、拥塞解除等操作完成拥塞控制任务。实验结果表明,无线通信网络中传输链路队列长度的平均值为29.2 Mbit,链路占比平均值为1.9%,平均传输速率为8.1 MiByte/s,验证了所设计方法的有效性。

双链路通信在露天矿山无人驾驶通信系统中的应用

信息时代给矿山行业带来了新的发展契机,露天矿山智慧化成为发展的必然趋势,无人驾驶作为智慧矿山的重要组成部分之一,为露天矿山生产提供强有力的支撑。在露天矿山无人驾驶场景中,确保通信的可靠性是重中之重,如果网络通信出现问题,则会对无人驾驶车辆的运行造成影响。因此,提升矿山网络通信的可靠性尤为必要,矿山企业可合理应用双链路通信技术,为无人驾驶提供通信保障。基于此,文章从露天矿山无人驾驶通信需求分析入手,论述了双链路通信技术在露天矿山无人驾驶通信系统中的应用。