基于差分信号强度的指纹室内定位算法

指纹定位以其低成本,高兼容性,高扩展性成为主流的室内定位技术。但是其依靠预先采集指纹强度的方式限定了其定位终端必须是采集信号的终端。这极大局限了指纹室内定位的应用场景。实验表明,不同终端之间在相同位置接收到相同接入点的信号可有5dBm-15dBm的误差。为了消去该误差对定位结果造成的影响,文中提出采用差分信号强度作为数据库指纹以计算定位结果。通过仿真,得到的结果表明这种定位方式明显提高了非采样终端的定位精度。     

Unsupervised learning of indoor localization based on received signal strength

Most indoor wireless sensor network localization methods require costly site surveys to collect fingerprint information for later comparison. Moreover, due to the dynamic nature of fingerprint information in indoor wireless environments, the need for site surveys may be ongoing. In this work, indoor localization is addressed with an unsupervised learning algorithm. Our novel algorithm based on received signal strength combines the information conveyed by both range‐based and range‐free localization with state‐of‐art optimization techniques. A specially designed hierarchical Bayesian hidden Markov model coupled with a particle filter helps mitigate non‐line‐of‐sight and multipath errors. This grid‐based data sample process, derived from the theory of Dirichlet processes, simplifies the global optimization problem of unsupervised learning by employing a single initial hyper‐parameter. Meanwhile, for obtaining accurate coordinates of mobile nodes, a unique semidefinite programming method is used to provide feedback to the radio propagation model. This feedback step can enable the grid‐based algorithms not only to establish the coordinates of a mobile node, but also to optimize the accuracy iteratively. Theoretical and experimental analyses indicate that the proposed algorithm can achieve better localization accuracy than conventional range‐based algorithms without adding computation cost. Copyright © 2016 John Wiley & Sons, Ltd.     

基于接收信号强度的WSN概率定位算法

定位对无线传感器网络的应用、操作和管理发挥着至关重要的作用.针对传感器节点的定位,提出了一种基于接收信号强度的概率定位算法.介绍了算法原理及实现过程,讨论了信标节点分布对该算法性能的影响,最后比较了本概率定位算法和最小二乘定位算法在传感器节点定位性能上的优劣.仿真结果表明,信标节点分布对未知节点的定位误差具有较大的影响,本定位算法的性能要优于最小二乘定位算法.     

Relay algorithm based on network coding in wireless local network

The network coding is a new technology in the field of information in 21st century. It could enhance the network throughput and save the energy consumption, and is mainly based on the single transmission rate. However, with the development of wireless network and equipment, wireless local network MAC protocols have already supported the multi-rate transmission. This paper investigates the optimal relay selection problem based on network coding. Firstly, the problem is formulated as an optimization problem. Moreover, a relay algorithm based on network coding is proposed and the transmission time gain of our algorithm over the traditional relay algorithm is analyzed. Lastly, we compare total transmission time and the energy consumption of our proposed algorithm, Network Coding with Relay Assistance (NCRA), Transmission Request (TR), and the Direct Transmission (DT) without relay algorithm by adopting IEEE 802.11b. The simulation results demonstrate that our algorithm that improves the coding opportunity by the cooperation of the relay nodes leads to the transmission time decrease of up to 17% over the traditional relay algorithms.     

基于IEEE802.11无线局域网的安全性研究

随着无线局域网的不断发展，网络安全问题日益突出。这里根据无线局域网信道的特点，首先介绍了无线局域网的安全需求，其次，描述了基于IEEE802．11无线局域网标准的有线等效保密（WEP）协议原理，并对WEP协议存在的安全漏洞及其相应的攻击进行了分析，最后，针对这些安全漏洞和攻击提出了增强无线局域网安全性的改进方案。     

An efficient handoff algorithm based on received signal strength and wireless transmission loss in hierarchical cell networks

Compared with the macrocell systems, the femtocell systems allow users to obtain broadband service with high data rate by using lower costs of transmit power, operation and capital expenditure. Traditional handoff algorithms used in macrocells cannot well satisfy the mobility of users efficiently in hierarchical macro/femto cell networks. In this paper based on the received signal strength (RSS) and wireless transmission loss, a new handoff algorithm in hierarchical cell networks called RWTL-HO is proposed, which considers the discrepancy in transmit power between macrocell and femtocell base stations. The simulation results show that compared with the conventional algorithm, the proposed algorithm improves the utilization of femtocells by doubling the number of handoffs; and in comparison with the handoff algorithm based on combining the RSSs from both macro and femto cell base stations, reduces half the number of redundant handoffs.     

基于局域信息和能量因素的WSN关键点判定算法

In the existing key node decision methods for wireless sensor network,the judgment index was so single that the result judged was deficient.In order to solve this problem,a new key node decision algorithm(KNDA)based on local information and energy factor was proposed.Firstly,the local information model based on the degree and neighbor information of node was established.Secondly,according to the residual energy of node and the change of network energy consumption after the node failed,the models of energy factors were established.Finally,an aggregative key node decision model was formed.Extensive simulation experiments were carried out in the MATLAB simulation platform,by comparing with other algorithms,the results verify that the key nodes obtained by this algorithm are more sufficient.Meanwhile when the key nodes judged by KNDA are protected,the network can show strong invulnerability.     

基于局域信息少数者博弈的拥塞控制算法

针对目前已有的拥塞控制算法普遍存在资源利用率低下、RTT不公平和多瓶颈链路不公平等问题,分析了网络拥塞控制中的博弈现象,考虑网络局域信息在拥塞控制过程中的影响,建立了一种基于局域信息少数者博弈的拥塞控制模型,提出并实现了一种基于局域信息少数者博弈的拥塞控制算法。仿真实验表明,该算法在保证瓶颈链路资源利用率的同时,有效地解决了异构RTT流的不公平性问题,实现了多瓶颈链路下的最大最小公平性。     

基于网络编码和ECC的无线体域网安全签名方案

针对无线体域网( WBAN)应用中人们关注的病患个人敏感数据在传输过程中容易受到攻击的安全问题,提出一种结合随机网络编码和椭圆曲线密码学( ECC)的安全签名方案。该方案首先在网络中引入随机网络编码建立多播网络模型,增加相同传输次数下的数据信息量;通过采用ECC算法对信息进行签名,保障病患相关生理信息的通信安全。该方案共有三个阶段,即创建、签名和验证阶段。理论证明了该方案是安全的,能够有效地对信息进行污染验证,并确定受攻击节点的位置。