Green wireless local area network received signal strength dimensionality reduction and indoor localization based on fingerprint algorithm

Green wireless local area network (WLAN) is an emerging technology to achieve both the purposes of power conservation and high‐speed accessing to the Internet because of the working on‐demand strategy adoption and high density access points (APs) deployment. Although it is good news to data traffic service, Green WLAN brings severe challenges to the indoor localization service based on fingerprint algorithm. Redundant APs will greatly enlarge the radio map and introduce a much heavier computation burden to the terminal for localization in the online phase. In addition, APs in Green WLAN are powered on and off to make balances between data traffic service demand and energy saving goals so that the received signal strength (RSS) sampled online and recorded in the radio map offline are rarely matched in the same detected AP number, which leads to asymmetric matching problem occurring in the fingerprint algorithm. In this paper, we propose to make a nonlinear dimensionality reduction on the RSS by local discriminant embedding algorithm to realize both the computation burden decreasing and asymmetric matching problem resolving for the fingerprint algorithm in Green WLAN. The simulation results show that our proposed methods could effectively reduce the computation burden in the online phase and make the fingerprint algorithm operate more robustly when the RSS is reduced to the intrinsic dimensionality in Green WLAN. Copyright © 2013 John Wiley & Sons, Ltd.     

基于多核最大均值差异迁移学习的WLAN室内入侵检测方法

无线局域网(WLAN)室内入侵检测技术是目前智能检测领域的研究热点之一,而传统基于数据库构建的入侵检测技术没有考虑复杂室内环境中WLAN信号的时变性,从而导致WLAN室内入侵检测系统的鲁棒性较差。为了解决这一问题,该文提出一种基于多核最大均值差异(MKMMD)迁移学习的WLAN室内入侵检测方法。该方法首先利用离线有标记和在线伪标记的接收信号强度(RSS)特征来分别构建源域和目标域;其次,通过构造最优迁移矩阵以最小化源域和目标域RSS特征混合分布之间的MKMMD;再次,利用迁移后的源域RSS特征与对应标签来训练分类器,并将其用于对迁移后的目标域RSS特征进行分类以得到目标域标签集;最后,迭代更新目标域标签集直至算法收敛,进而实现对目标环境的入侵检测。实验结果表明,该文所提方法在保证较高检测精度的同时,能够有效克服信号时变性对检测性能的影响。     

Kernel-Based Positioning in Wireless Local Area Networks

The recent proliferation of location-based services (LBSs) has necessitated the development of effective indoor positioning solutions. In such a context, wireless local area network (WLAN) positioning is a particularly viable solution in terms of hardware and installation costs due to the ubiquity of WLAN infrastructures. This paper examines three aspects of the problem of indoor WLAN positioning using received signal strength (RSS). First, we show that, due to the variability of RSS features over space, a spatially localized positioning method leads to improved positioning results. Second, we explore the problem of access point (AP) selection for positioning and demonstrate the need for further research in this area. Third, we present a kernelized distance calculation algorithm for comparing RSS observations to RSS training records. Experimental results indicate that the proposed system leads to a 17 percent (0.56 m) improvement over the widely used K-nearest neighbor and histogram-based methods     

基于核直接判别分析和支持向量回归的WLAN室内定位算法

该文针对RSS信号的时变性降低WLAN室内定位精度的问题,提出了一种新的基于核直接判别分析和支持向量回归的定位算法。该算法利用核直接判别分析对原始RSS信号进行定位信息重组,去除冗余定位特征和噪声,提取最具判别力的定位特征,然后采用支持向量回归算法建立定位特征与物理位置的映射关系。实验结果表明,提出算法的定位精度明显高于传统定位算法,且大大降低了离线阶段数据采集的工作量。     

基于偏度-峰度检验的无线局域网室内定位算法

针对室内无线局域网环境下接收信号强度(RSS,received signal strength)样本总体分布不一致而产生较大定位误差的问题,提出了一种基于偏度-峰度检验的室内定位算法.利用偏度-峰度检验法检验RSS样本是否来自正态总体,接受零假设的样本用正态分布近似其总体分布,拒绝零假设的样本用核函数估计其概率密度.实验结果表明提出算法的定位精度比传统算法提高15％以上,而且在相同的定位精度下,能明显降低离线阶段的工作量.     

Signal Strength Ratio Based Vertical Handoff Decision Algorithms in Integrated Heterogeneous Networks

In this paper, we propose the signal strength ratio (SSR) based vertical handoff (VHO) algorithms and the averaged received signal strength (ARSS) based VHO algorithms for integrated networks of wireless local area network (WLAN) and 3G network. The performance of our proposed VHO algorithms with hysteresis and dwell timer approaches has been investigated for two different topologies of integrated heterogeneous network. Two different network topologies consider two different types of radio cell arrangement. A mobile terminal (MT) is moving within the coverage area of WLAN and 3G with constant velocity. The received signal strength at the MT of interest is measured at different sampling instant. The received signal strength with other additional parameters is used to determine the condition of VHO. We evaluate the decision delay, and the number of vertical handoffs between WLAN and 3G network using the proposed VHO algorithms. We compare the performance of our proposed VHO algorithms with existing RSS based VHO algorithm. Our proposed SSR and ARSS based VHO algorithms provide less decision delay as compared to existing RSS based VHO algorithm. Further, ARSS with dwell timer based VHO algorithm provides better performance than other VHO algorithms.     

面向WLAN室内定位的T检验样本容量优化方法

WLAN（Wireless Local Area Networks）室内定位已受到人们广泛的关注,而在离线指纹采集阶段常常容易造成位置指纹RSS数据采集的盲目性和不可靠性,并忽略所需采集RSS（Received Signal Strength）样本容量与定位性能的关系.为了解决这一问题,本文提出一种面向WLAN室内定位的T检验样本容量优化方法.该方法在离线阶段利用OC（Operating Characteristics）函数优化指纹数据库允许的最小RSS样本容量,而在在线阶段利用T检验方法对目标终端进行粗定位,并进而提出基于T检验的KNN（K-Nearest Neighbour）算法以完成对目标终端的精定位.此方法用有限的样本容量获得较稳定的定位性能分析结果,显著地减少了大量的人力和时间开销.     

Research on indoor localization algorithm based on kernel principal component analysis

An indoor localization algorithm based on kernel principal component analysis (KPCA) was proposed.It applied KPCA to train the original location fingerprint (OLF) and extract the nonlinear feature of the OLF data at the offline stage,such that the information of all AP was more efficiently utilized.At the online stage,an improved weight k-nearest neighbor algorithm for positioning which could automatically choose neighbors was proposed.The experiments were carried out in a realistic WLAN environment.The results show that the algorithm outperforms the existing methods in terms of the mean error and localization accuracy.Moreover,it requires less times of RSS acquisition and AP number.     

Vertical handoff algorithm in heterogeneous networks for reducing interference

A vertical handoff decision algorithm in heterogeneous networks composed of CDMA Cell Networks (CN) and Wireless Local Area Network (WLAN) is proposed to minimize the total interference in CDMA. The scope of WLAN is determined by minimizing interference and each communicating node shall handoff to WLAN as soon as it enters the scope. We first propose a model for heterogeneous networks, and based on it we obtain the close-form expression of interference. In order to minimize interference, we use simulation annealing method to get the WLAN radius, which is called basic algorithm. In order to reduce the interference further, we improve the basic and get the enhanced algorithm. Through numerical computing, we analyze the interference in condition of different call arrive rates, and results show that the enhanced can reduce interference more greatly than the basic.     

基于距离估计和NNSS的室内定位算法

基于室内RSS,在IEEE802.11信道模型基础上,文中提出了一种综合考虑数据库特性和信号传输信道特性的WLAN定位算法,通过仿真试验证明,该算法能够达到较高的定位精度,对参与定位的AP数量的灵敏度较低,从而具有很好的定位精度稳定性.     

Adaptive vertical handoff algorithm in heterogeneous networks

The integration of cellular network (CN) and wireless local area network (WLAN) is the trend of the next generation mobile communication systems, and nodes will handoff between the two kinds of networks. The received signal strength (RSS) is the dominant factor considered when handoff occurs. In order to improve the handoff efficiency, this study proposes an adaptive decision algorithm for vertical handoff on the basis of fast Fourier transform (FFT). The algorithm makes handoff decision after analyzing the signal strength fluctuation which is caused by slow fading through FFT. Simulations show that the algorithm reduces the number of handoff by 35%, shortens the areas influenced by slow fading, and enables the nodes to make full use of WLAN in communication compared with traditional algorithms.     

基于Mann-Whitney秩和检验的无线局域网室内映射与定位方法

该文提出一种基于Mann-Whitney秩和检验的无线局域网(WLAN)室内映射与定位方法。该方法首先根据实际定位精度需求对目标区域中的运动路径进行分段,同时基于Mann-Whitney秩和检验方法合并相似运动路径片段;然后,利用一种基于相似接收信号强度(RSS)序列片段的信号聚类算法,保证同一聚类中RSS样本的物理邻接关系;最后,通过骨干节点的扩散映射,建立物理与信号空间的映射关系,实现对运动用户的定位。实验结果表明,相比于已有WLAN室内映射与定位方法,该文方法在无需运动传感器辅助和构建位置指纹数据库的条件下,能够实现更高的映射与定位精度。     

Anonymous crowdsourcing-based WLAN indoor localization

In order to solve the problem of location privacy under big data and improve the user positioning experience, a new concept of anonymous crowdsourcing-based WLAN indoor localization is proposed by employing the Micro-Electro-Mechanical System (MEMS) motion sensors as well as WLAN module in off-the-shelf smartphones. First of all, the crowdsourced motion traces with similar Received Signal Strength(RSS) sequences are assembled into a motion graph. Second, the mobility map is constructed according to traces segmentation and clustering. Third, the pixel template matching is adopted to physically label the pre-constructed mobility map. Finally, the robust Extended Kalman Filter (EKF) is designed to perform localization by matching the newly-collected RSS measurements against the mobility map. The extensive experimental results show that the proposed approach is capable of constructing a physically-labeled mobility map from the sporadically-collected crowdsourced motion traces as well as achieving satisfactory localization accuracy in a cost-efficient manner.     

Seamless vertical handoff using modified weed optimization algorithm for heterogeneous wireless networks

In the global scenario, a variety of wireless access networks are available. Different types of applications such as real time, nonreal time, and high bandwidth availability are used for heterogeneous wireless networks. Therefore, it is necessary for a service provider to make an appropriate connection support. For better performance, connections are to be exchanged among the different networks using seamless vertical handoff (VHO). The proposed algorithm shows the effect of optimization technique, which involves handoff decision process using vertical handoff triggering and selection of the network. The handoff triggering is initiated by using the received signal strength (RSS). In traditional method, handoff triggering is initiated by using RSS only. This method, modified weed optimization (M-WO) algorithm, reduces the unnecessary handoff by considering both RSS and velocity of the mobile node in handoff triggering. The parameters such as battery lifetime, handoff call dropping rate, load, dynamic weights adaptation and so on are to be considered individually or combined to make an effective network selection process. This paper highlights a novel effect ofM-WOalgorithm for decision making during the VHO. Our effort is to essentially optimize the system load, so that it reduces the handoff call dropping rate and the battery power consumption of the mobile node (MN). Weight of each QoS metrics is adjusted along with the networks changing conditions to trace the M-WO. Therefore, the novel VHO decision-making algorithm is superior to the existing SSF and OPTG methods. The simulation results show that the performance ofM-WOalgorithm is far better than SSF andOPTGmethods in terms of load, handoff call dropping rate and battery lifetime of MN.     

基于半马尔可夫链的WLAN/CDMA联合呼叫接入控制

下一代网络（NGN）将融合多种异构无线接入网络。为了在满足QoS限制下,最大化网络收益,在对WLAN／CDMA等效带宽的研究基础上,提出一种基于SMDP（半马尔可夫决策规划）的最优的联合呼叫接入控制（JCAC）方案,方案考虑了WLAN和CDMA网络间的相互影响,并将网络连接的联合呼叫控制问题等效成一个半马尔可夫决策过程,仿真表明方案相对于离散时间的MDP和在MDP基础上的JCAC算法具有明显的优势。     

Effective VoIP call routing in WLAN and cellular integration

In cellular-WLAN integration, a dual-mode mobile station (MS) typically disables the WLAN module for power saving. A major problem is that for an incoming VoIP call (or data session), the MS will not be able to receive this call from the WLAN. It turns out that the call is directed to the cellular network. This letter proposes a simple push solution where an MS can accurately detect a VoIP call from paging signaling of the cellular network. Then the WLAN module of the MS is turned on and the VoIP call is connected to the MS through the relatively inexpensive WLAN.     

A call admission control framework for voice over WLANs

In this article a call admission control framework is presented for voice over wireless local area networks (WLANs). The framework, called WLAN voice manager, manages admission control for voice over IP (VoIP) calls with WLANs as the access networks. WLAN voice manager interacts with WLAN medium access control (MAC) layer protocols, soft-switches (VoIP call agents), routers, and other network devices to perform end-to-end (ETE) quality of service (QoS) provisioning and control for VoIP calls originated from WLANs. By implementing the proposed WLAN voice manager in the WLAN access network, a two-level ETE VoIP QoS control mechanism can be achieved: level 1 QoS for voice traffic over WLAN medium access and level 2 QoS for ETE VoIP services in the networks with WLANs as the local access. The implementation challenges of this framework are discussed for both level 1 and level 2. Possible solutions to the implementation issues are proposed and other remaining open issues are also addressed.     

WLAN-based Outdoor Localisation Using Pattern Matching Algorithm

Location detection is a very important issue in a wireless environment, allowing realisation of several useful services linked to the knowledge of the position of a mobile user (e.g. path optimisation, management of field crew in a large plant, providing a mobile robot with autonomous capabilities). Literature presents many approaches for location detection of a mobile device in a WLAN. One of these is based on the use of a pattern matching algorithm which provides for the position of the mobile device given the Radio Signal Strength (RSS) values received by it. Generally, localisation in WLAN environment is limited to indoor scenarios. Although GPS is commonly used for outdoor location detection, localisation in a WLAN communication infrastructure may be realised also for outdoor areas. The main advantage is a save in the hardware needed for the localisation, as it only requires the use of the WLAN communication card; further, the current limits of GPS, which may introduce not negligible errors in outdoor location detection, encourages the investigation of other techniques for outdoor localisation. On account of what said, the first aim of the paper is to investigate the feasibility of outdoor localisation of a mobile device in a WLAN environment; an IEEE 802.11b-based WLAN will be considered. Outdoor localisation has been realised using a pattern matching algorithm and the relevant performance, measured in terms of location errors, has been evaluated and compared with that commonly provided for by a GPS device. Then the paper will present a proposal for localisation, aimed to reduce the complexity typically featured by the pattern matching algorithm based approach when used for wide areas; the proposal is based on the use of a signal propagation model able to predict the RSS values available in each position of a IEEE 802.11b WLAN. Performance of the novel approach has been evaluated for outdoor localisation and the main results achieved will be shown in the paper. Finally, use of a Kalman filter for the location detection, will be presented in order to improve the performance of the pattern matching algorithm, making this technique very attractive for outdoor use.

On the support of voice call continuity across UMTS and wireless LANs

In this paper, we address the architecture and the procedures that can enable voice call handover from UMTS to WLAN and we also study how efficiently the WLAN can support the voice calls transferred from UMTS. Our study is based on a practical simulation model that lets us quantify the maximum number of voice calls that can be handed over from UMTS to WLAN, subject to maintaining the same level of UMTS QoS and respecting some WLAN policies. In addition, several other voice call performance metrics are derived. Our results indicate that an IEEE 802.11e access point can support a limited number of voice calls handed over from UMTS, which depends primarily on the applied WLAN bandwidth sharing policy (i.e., how the bandwidth is shared between WLAN voice and data users) and the QoS requirements. The performance of the WLAN scheduling algorithm is also of paramount importance and in our study we consider the so‐called ARROW scheduler. Although the simulation results are derived for a specific bandwidth sharing policy, they can readily be scaled and provide practical upper bounds for the number of UMTS voice calls that can be seamlessly admitted to a WLAN access point. Copyright © 2007 John Wiley & Sons, Ltd.     

一种LTE与WLAN间垂直切换新算法

为提高用户在异构网络中的服务质量(QoS),减少切换产生的乒乓效应,文中提出了一种LTE和WLAN网络垂直切换新算法。该算法考虑了衰落对接收信号强度(RSS)的影响,基于RSS选出目标网络,根据用户移动速度并结合代价函数选出最佳网络,代价函数中采用了层次分析法来确定时延、资费和用户偏好等参数的权重。仿真结果表明,文中所提的垂直切换算法有效降低了“乒乓效应”,并提高了通信网络的服务质量。