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Li Li Wang Yang Md Zakirul Alam Bhuiyan Guojun Wang 《Wireless Communications and Mobile Computing》2016,16(15):2225-2237
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. 相似文献
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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. 相似文献
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基于IEEE802.11无线局域网的安全性研究 总被引:1,自引:0,他引:1
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。 相似文献
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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. 相似文献
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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. 相似文献
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