Velocity Of Mobile Users Research Articles

MPDHD-A Handover Decision Scheme for Seamless Connectivity in Wireless Network

Handover is one of the major concerns arising in wireless network due to increasing demand of services by the customers. Different studies have been performed to attain a seamless handover. Researchers are implementing novel technologies so that efficient decision can be made to maintain effective communication. Multilayer feed forward artificial neural network has been implemented in a recent study in which Received Signal strength indicator (RSSI), monetary cost, Data rate and Velocity of mobile users in the network are taken into account for handover decision in wireless network. Due to several limitations of this technique, a novel method- Multiple parameters dependent Handover decision (MPDHD) is presented in which Sugeno fuzzy model is amalgamated with neural network to form an intelligent system. In the system, neural network is trained by the fuzzy model which reduced the complexity of the existing work. Also along with the parameters used in existing work, a new user metric-Load is introduced to check the availability of the base station with minimum load of users connected to it. The simulation of the proposed work is carried out in the MATLAB environment. From, the experimental results, it is concluded that MPDHD is better than existing approaches and reduced the handover probability in the network.

Trajectory Clustering and k-NN for Robust Privacy Preserving Spatiotemporal Databases

In the context of this research work, we studied the problem of privacy preserving on spatiotemporal databases. In particular, we investigated the k-anonymity of mobile users based on real trajectory data. The k-anonymity set consists of the k nearest neighbors. We constructed a motion vector of the form (x,y,g,v) where x and y are the spatial coordinates, g is the angle direction, and v is the velocity of mobile users, and studied the problem in four-dimensional space. We followed two approaches. The former applied only k-Nearest Neighbor (k-NN) algorithm on the whole dataset, while the latter combined trajectory clustering, based on K-means, with k-NN. Actually, it applied k-NN inside a cluster of mobile users with similar motion pattern (g,v). We defined a metric, called vulnerability, that measures the rate at which k-NNs are varying. This metric varies from 1 k (high robustness) to 1 (low robustness) and represents the probability the real identity of a mobile user being discovered from a potential attacker. The aim of this work was to prove that, with high probability, the above rate tends to a number very close to 1 k in clustering method, which means that the k-anonymity is highly preserved. Through experiments on real spatial datasets, we evaluated the anonymity robustness, the so-called vulnerability, of the proposed method.

Second-Order Statistics Channel Model for 5G Millimeter-Wave Mobile Communications

Millimeter waves (mmWs) are considered as one of the most promising technologies for future 5G networks. The current study presents a three-dimensional (3D) geometry-based channel model for a fixed-to-mobile non-isotropic Ricean mmW scattering environment. According to this 3D reference model, the mmW complex faded envelope impulse response has been derived. This impulse response has been employed in estimating the second-order statistics of the mmW channel model. These statistics comprise both the 3D faded envelope level crossing rate (LCR) and the average fade duration (AFD). As a consequence, these statistics may contribute to the 5G network planning and engineering, especially for studying the phenomenon of fading with time, the 5G system characteristics, the handoff scenarios, and the relationship between the mobile user velocity and the fading rate. Furthermore, this study also provides a stochastic sum-of-sinusoids mmW channel simulator for comparison with analytical results. Numerical results validated the proposed analytical model and revealed the effect of channel parameters on both LCR and AFD in the mmW bands.

Effect of velocity on handover parameters in wireless networks

In this era of technology, wireless networks are supposed to provide continuous access to mobile users while they are roaming from one access network to another. In this paper, effect of velocity of mobile user, on handover parameters, is examined. The link down time and the handover delay are considered as handover parameters. The simulation results show that the velocity of mobile user has great impact on handover parameters. Moreover, the performance of handover algorithms also varies with velocity of mobile users. This evaluation is done based on probability of early handover and service disruption probability for different algorithms. Thus, it has been concluded that the velocity should be kept in mind while designing handover algorithms.

Effect of velocity on handover parameters in wireless networks

In this era of technology, wireless networks are supposed to provide continuous access to mobile users while they are roaming from one access network to another. In this paper, effect of velocity of mobile user, on handover parameters, is examined. The link down time and the handover delay are considered as handover parameters. The simulation results show that the velocity of mobile user has great impact on handover parameters. Moreover, the performance of handover algorithms also varies with velocity of mobile users. This evaluation is done based on probability of early handover and service disruption probability for different algorithms. Thus, it has been concluded that the velocity should be kept in mind while designing handover algorithms.

Cross Layer Based Dynamic Handover Decision in Heterogeneous Wireless Networks

Heterogeneous wireless networks encompass different radio access technologies to offer services as per the requirements of the users at anytime and anywhere. In such networks, mobile users have to undergo vertical and horizontal handovers to realize seamless communication with guaranteed quality of service. In this paper, we propose cross layer based dynamic handover decision algorithm to maximize resource utilization and to attain high QoS. The parameters measured at different layers are used through media independent handover functionality to estimate handover requirement and to select an appropriate target network. Based on user's preferences, different weights are assigned to handover decision parameters using fuzzy analytical hierarchical process. The weights, assigned to decision parameters, are made adaptive to call time, velocity of mobile user, type of application and remaining battery life of the mobile handset. A popular multiple attribute decision making technique, TOPSIS (technique for order preference by similarity to the ideal solution), is adopted to choose the most suitable target network. Numerical results are obtained through computer simulation for preference scores of different networks, security, end to end delay and available data rate, which show that QoS perceived by the end user is maintained consistently in varied conditions of the network and applications.

Cooperative data download on the move in indoor hybrid (radio‐optical) WLAN‐VLC hotspot coverage

ABSTRACTIn this work, we study the performance of hybrid (radio‐optical) wireless local area network (WLAN)‐visible light communication (VLC) hotspot and compare its performance with stand‐alone VLC‐only or WLAN‐only hotspot cases. We consider data download on move scenario in an indoor environment for single‐user and for multi‐user cases. Short‐range spotlighting cell so‐called VLC hotspot is considered for high data rate region. On the other hand, WLAN hotspot is used for providing reliable connectivity and moderate data rate support. Throughput–distance relationships are developed both for WLAN and VLC to evaluate the performance of indoor environment by taking into account the radio and optical channel characteristics. The impact of the velocity of mobile user(s) and the number of VLC hotspots present in the considered service area are also considered on the performance of hybrid WLAN‐VLC hotspot. Simulations have been performed to evaluate the performance of such network for data downloading on move scenario by taking into account performance metrics such as file size, average connectivity and system throughput. Simulation results reveal that the considered hybrid WLAN‐VLC performs always better than stand‐alone VLC‐only or WLAN‐only hotspots both for single and multi‐user cases. Copyright © 2014 John Wiley & Sons, Ltd.

Analytical modeling and resource planning for cognitive radio systems

AbstractCognitive radio heralds the next step in the evolution of wireless communications. In this paper, an analytical model for infrastructure based cognitive radio systems is proposed, and its performance is evaluated under bursty traffic scenarios in a multiple cell environment. Performance metrics like probabilities of dropping and blocking for primary and secondary users as well as forced termination and forced frequency handoff for secondary users are investigated, and the analytical model is verified with simulations. In addition to the analytical model, a new resource planning method is proposed to compensate for uneven traffic load distribution. The proposed method considers offered traffic, hop count to the heavily loaded cell, and velocity of mobile users during resource planning and performs better in terms of probability of blocking, dropping, and forced termination. The proposed method is promising in balancing the system performance measures, yet there is room for further improvement for finding a closed formula for the proposed analytical model. Copyright © 2010 John Wiley & Sons, Ltd.

Mobile velocity estimator for Ricean fading channels

A novel technique is presented for the estimation of the maximum Doppler shift and thus the mobile user velocity in a Ricean faded channel using the second-order statistics of the received signal. The estimator is shown to perform well under various channel conditions.