一种在物理层实现协作分集的无线传感器网络

无线传感器网络通常具有存在大量冗余节点、共同的传送目标和能量资源极其有限等特性,因此可以在不同的协议层面上实现协作传输以提高能量有效性,从而延长网络的生命周期.本文研究了一种在物理层进行协作分集完成无线传感器网络中远距传输的方法,提出了可实现的信令和远程接收算法,分析了等效网络多径信道特性和远程接收机能够获得的最大分集增益以及影响分集增益的因素,提出了在分布式网络中提高空间分集增益的方法.     

一种机会空时协作网络编码及其性能分析

本文提出了一种机会空时协作网络编码(OST-CNC,opportunistic space-time-coded cooperative network coding),该技术将协作分集技术和网络编码技术有机结合,能够克服无线信道衰落、提高系统资源利用率和网络吞吐.针对间隔两跳的链状网络中进行端到端信息交换的情形,分析了OST-CNC的中断性能和获取的网络编码增益,结果表明:相对于传统的数据交互策略,机会空时协作网络编码在获得全分集(获得的分集阶数为参与协作的节点数)的同时,也获得了4/3倍的渐近网络编码增益,由于机会路由的形成,OST-CNC的网络编码增益在中低信噪比(SNR)区域更为突出.     

编码协作分集研究与展望

用户协作方案是协作分集研究的一个重要方面。在慢衰落和快衰落信道条件下,均能带来传输性能改善的编码协作分集方案,是目前协作分集方案中备受关注的一种。尤其在将空时编码的思想引入该方案后,更带来了编码协作分集在快衰落信道条件下的良好性能。用户要想从协作中受益,协作伙伴/中继节点的选取是编码协作分集中一个重点。     

一种基于空时码的协作网络编码技术及其性能分析

该文提出了一种基于空时码的协作网络编码技术(Cooperative Network Coding based on Space-Time code,ST-CNC),该技术将协作分集技术和网络编码技术有机结合,能够克服无线信道衰落,提高系统资源利用率和网络吞吐。推导了采用ST-CNC的两跳链状网络中端到端信息交换的误比特率,分析了该技术带来的分集增益和网络编码增益。结果表明:相对于传统的多跳链路的数据交互策略,该技术能够带来明显的性能增益。最后通过仿真验证了分析结果的正确性。     

一种用于信道分集性能研究的新方法

对于无线通信系统来说,信道分集是实现可靠通信、提高通信性能的有效方法.目前,分集复用折衷性能是衡量不同信道分集技术性能的常用方法,该法仅适应于高信噪比情况.本文基于信道分集因子统计特性从一个新的角度对信道分集进行了研究,针对传统信道分集技术提出了一种新的信道分集性能研究方法,理论分析及仿真结果表明方法是有效的.     

基于网络编码的用户协作分集系统性能分析

针对非协作通信和传统协作通信系统不能达到高天线分集增益的问题,提出基于网络编码的用户协作系统模型.研究了基于网络编码不同协作用户的天线分集增益,并分析非协作机制、传统用户协作机制和基于网络编码用户协作机制的中断概率.理论分析和系统仿真表明,基于网络编码的用户协作系统能显著降低系统中断概率,获得更大的分集增益,且协作用户数越多,系统分集度越好.     

基于分布式中继选择的自适应协作传输方案

协作分集通过使网络用户共享彼此天线以形成虚拟多天线阵列,可以显著提高网络容量,然而针对网络拓扑的动态变化与无线传输的时变特性,仅靠协作分集并不能十分有效地解决这些问题,必须结合考虑相应的自适应传输策略.本文提出动态网络环境中协作中继的最佳选择准则,在此基础上给出最佳协作中继的分布式选择协议.根据协作中继与源节点间的无线信道质量,进一步提出一种自适应协作传输方案,以有效抵抗多用户网络环境中的无线衰落.此外,对自适应协作传输方案的误码性能,在瑞利衰落信道下进行相应的理论分析,得到了系统误比特率的解析表达式,据此给出数值仿真实验以进行性能比较.结果表明:相对于传统协作分集而言,本文提出的自适应协作传输方案获得了进一步的性能增益,误比特率显著下降.     

基于网络编码的无线网络分布式协作通信机制

 本文提出了一种基于无线网络编码的协作通信机制NCCC.无线网络编码能够在取得合作分集的性能增益的同时,降低网络中断概率.分布式中继节点选择算法是NCCC机制的核心,该算法根据即时信道状态,选择执行网络编码操作的最优中继节点.理论和仿真结果证明, NCCC机制可以提高无线网络双向多信源多信宿传输的性能和鲁棒性.     

无线传感网物理层协作分集的性能分析

该文针对无线传感网中的远距传输问题,研究了一种无需网络同步和正交信道的协作分集方法的性能,给出了在两种典型信道中当解码转发存在误差传播时远程目的节点的误码率及分集指数;分析了当转发节点间为白高斯信道时增加协作节点数能够提高目的节点性能的条件。研究结果表明,当转发节点间为白高斯信道时,只要转发节点处于正常工作点,增加节点数就能提高目的节点的性能;当转发节点间为瑞利平衰落信道时,只有当转发节点处于一定位置时,协作分集相对于直接发送或传统空间分集才有性能增益;当转发节点间为瑞利平衰落信道时增加跳数性能更好,为白高斯信道时增加分支数更有效;当转发节点间为瑞利平衰落信道时,误差传播将使目的节点的分集指数为1,但在较低信噪比条件下对分集性能影响很小。     

一种无线Mesh网络中基于协同通信的多包接收方法

协同通信容许移动节点共享彼此的天线以构建虚拟多入多出系统,可有效获得空间分集增益。为利用虚拟多入多出信道的分集增益,该文提出了一种在无线Mesh网络上行链路中采用协同策略的多包接收方法。该方法中提出由发生冲突的Mesh终端及其协同节点构建虚拟多入多出信道,且多天线Mesh路由器通过串行干扰消除算法来快速分离冲突包。理论分析和仿真结果表明该方法可充分利用空间资源,相比NDMA和TDMA可有效提高系统的有效吞吐量并降低时延。     

Collision resolution in packet radio networks using rotationalinvariance techniques

This paper deals with the multiuser medium access problem in the packet radio environment. Under the framework of network diversity multiple access (NDMA), a previously proposed medium access method, a blind collision resolution scheme is proposed employing rotational invariance and factor analysis techniques. The proposed approach (dubbed B-NDMA for blind NDMA) overcomes the difficulty of orthogonal identification codes required by the original protocol, thereby improving channel utilization and system capacity, while being insensitive to multipath effects and synchronization errors. Performance issues of the proposed technique are addressed both analytically and numerically     

一种基于跨层设计的协作多址接入方案

协作通信容许移动节点共享彼此间的天线以构建虚拟多入多出系统,可以有效获得空间分集增益。提出了一种结合网络分集多址接入(NDMA)和协作通信的随机接入方案,利用多天线接收,可以快速分离冲突数据包,实现多包接收的能力。理论分析和仿真结果表明,所提方案能充分利用空间资源,相比传统NDMA方案和TDMA方案,可以显著提高系统的有效吞吐量。     

Cooperative Distributed MIMO Channels in Wireless Sensor Networks

The large number of network nodes and the energy constraints make Wireless Sensor Networks (WSN) one of the most important application fields for Cooperative Diversity. Node cooperation increases the spatial diversity of wireless channels and, thus, reduces the transmitted power. In this paper, we propose a multi-hop WSN with nodes grouped in cooperative clusters that exploits transmit and receive cooperation among cluster nodes. Multi-hop transmission is carried out by concatenating single cluster-to-cluster hops, where every cluster-to-cluster link is defined as a cooperative distributed multiple-input-multiple-output (MIMO) channel. Transmit diversity is exploited through a time-division, decoder-and-forward, relaying scheme based upon two time slots: the Intracluster Slot, used for data sharing within the cluster, and the Intercluster Slot, used for transmission between clusters. At the receiver side, a distributed reception protocol is devised based upon a Selection Diversity algorithm. The proposed multi-hop cooperative WSN is optimally designed for minimum end-to-end outage probability by deriving the optimum time and power allocated on the intracluster and intercluster slots of every single hop, given a per-link energy constraint. A simplified suboptimum resource allocation is also proposed, which performs close to the optimal policy. Results show that the proposed scheme achieves diversity equal to the equivalent MIMO system and significantly reduces energy consumption with respect to. the non-cooperative channel     

基于时空多样性编码的低轮值无线传感器网络可靠传输算法

提出了适用于低轮值无线传感器网络的可靠传输算法,主要特点是发掘并利用低轮值无线传感器网络特有的时空相关性,结合编码机制以获得较高的能量效率和较低的传输时延。针对编码块在多条路径上的最优分配问题进行了建模。由于求解最优策略是NP难题,给出了近似算法,并通过仿真分析了不同参数对近似算法的影响。仿真结果表明,基于时空多样性编码的分配算法能够在较低的能量开销条件下,实现低时延的可靠传输。     

Decentralized multiuser diversity with opportunistic packet transmission in MIMO wireless sensor networks

In this study, we consider a single-hop wireless sensor network where both the sensor nodes and the controller node have multiple antennas. We focus on single beam opportunistic communication and propose a threshold-based medium access control (MAC) scheme for uplink packet transmission which exploits multiuser diversity gain without feedback in a decentralized manner. Packet transfer from sensor nodes to the controller node is initiated when the channel quality of any node exceeds the predefined threshold based on the effective signal-to-noise ratio (ESNR) measurements at the sensor nodes through linear combining techniques. The optimum threshold is determined to maximize the probability of successful packet transmission where only one sensor node transmits its packet in one time-slot. The proposed scheme trades the successful packet rate to increase the SNR of the successful packets assuming Rayleigh fading and collision-based reception model. Computer simulations confirm that proposed scheme has higher successful packet SNR compared to the simple time division multiple access (TDMA)-based MAC scheme with round-robin fashion. The use of multiple antennas at the sensor nodes can also improve the throughput of proposed scheme compared with our previous scheme without implementing the spatial diversity at the SNs.     

双向中继系统中基于对角空时码的空间调制传输算法

在双向中继系统中,针对采用SSK传输不能获得发射分集且频谱效率较低的问题,提出了一种对角空时码空间调制算法,简称为DSTC-SM。该算法在源节点处采用DSTC-SM码字发送信号,在中继节点处配置单根天线对接收到的信号进行放大并将其转发至目的节点。DSTC-SM码字的构造中以对角码作为基本码块,并与空间调制（SM）技术相结合,采用循环结构来激活不同的天线。此外,通过对旋转角度的优化使该方案在即使只激活一根天线的情况下仍然可以获得发射分集增益。仿真结果表明,所提的算法比现有的算法具有较好的误码性能。     

Energy-Aware Healthcare System for Wireless Body Region Networks in IoT Environment Using the Whale Optimization Algorithm

Wireless Sensor Network (WSN) is one of the most significant technologies that typically involves of a large number of wireless sensor nodes with sensing, communications and computation capabilities. The sustained operation of WSN is achieved through the efficient consumption of node energy. The WSN is used to many applications especially military, science and medical. The WSN performance may be affect some issues such as load balancing, security and reduce energy consumption of the nodes. These issues must be reduced to enhance performance of the WSN structure in different applications. Henceforth, in this paper, Hybrid Emperor Penguin Optimization (EPO) is developed to solve load balancing, security enhancement and reduce energy consumption in WSN. The hybrid EPO is combined with Atom Search Optimization (ASO) algorithm, it is used to improve the updating function of the EPO algorithm. Three major objective functions can be considered towards improve the performance of WSN like load balancing, security enhancement in addition energy consumption reduction. The load balancing can be achieved by optimal clustering scheme which attained applying proposed hybrid EPO. The security also enhanced in WSN with the help of hybrid EPO by computing security measures. Similarly, energy consumption of WSN is achieved optimal routing scheme by hybrid EPO algorithm. The proposed methodology is developed to manage three objectives which is a major advantage. The projected technique can be implemented by NS2 simulator for validation process. The projected technology is contrasted with the conventional methods such as EPO and ASO respectively. The projected technique is evaluated in terms of delivery ratio, network lifetime, overhead, energy consumption, throughput, drop and delay.

     

基于人工蜂群寻优算法的WSN中继节点布局方案

无线传感器网络(WSN)环境下,中继节点位置布局性能优劣是影响网络寿命的关键因素之一。目前,针对三维空间高密度WSN,缺少能够在硬件成本和连通性双重约束条件下提高网络寿命的中继节点位置布局方案。基于网格布局方式,提出了一种基于人工蜂群优化算法的中继节点布局方案(ABC-RNDS)。ABC-RNDS方案采用双层网络拓扑结构,首先使用最小生成树法构建骨干网络,再使用人工蜂群优化算法通过网络参数寻优和限制中继节点总数的方法实现网络寿命的延长。实验验证分析表明,在成本和连通性受约束的条件下,ABC-RNDS算法与传统方案相比能够显著提高网络寿命。     

Detection of collision using optimized deep model and mitigation of collision using dolphin ant lion optimizer in wireless sensor network

Wireless sensor network (WSN) comprises automatic sensors that are dispersed into a huge region. WSN is constructed from huge sensors, which is allocated to a particular task and the majority of task involves reporting and monitoring. However, as the network can be extended to several sensor nodes, there is a high chance of collision. Thus, this paper devises a novel technique for performing both collision detection and mitigation in WSN. Initially, the simulation of WSN is performed, and then the selection of cluster head is done using fractional artificial bee colony (FABC). Here, the network-based parameter is extracted that involves received signal strength index (RSSI), priority level, delivery rate, and energy consumed. The deep recurrent neural network (DRNN) is adapted for collision detection. Here, the training of DRNN is done using lion crow search optimizer (LCSO). After collision detection, the collision mitigation is performed with a pre-scheduling algorithm, namely dolphin ant lion optimizer (Dolphin ALO). Here, fitness is considered for collision mitigation that includes energy, sleep index (SI), delivery rate, priority level, E-waste, and E-save. The proposed method outperformed with the smallest energy consumption of 0.185, highest throughput of 0.815, highest packet delivery ratio (PDR) of 0.815, and highest collision detection rate of 0.930.