Short Survey of Wireless Indoor Positioning Techniques and Systems

Smart city offers different services to different people depending on a wish list. It fulfills people's aspiration level, wherever there is willingness to change and to reform. Due to the complexity people movement within and between cities, localization techniques became popular with the global positioning system for outdoor applications, followed by Personal Networks (PNs) localization for indoor applications. PN are designed to provide a flexible and fast wireless communication between user’s devices and other devices, in various indoor environment places. PN mainly uses indoor positioning systems (IPSs) for improving numerous factors such as Self-organizing sensor networks, location sensitive billing, ubiquitous computing, context- dependent information services, tracking, and guiding. This paper gives a short survey of some kinds of IPSs, and focuses on triangulation to predict the target location, where for example it calculates the distance by measuring time difference of signals arrival (TDOA) over Orthogonal Frequency Division Multiplexing (OFDM), as one of several techniques identify the distance between the transmitters and receiver

Link Layer Priority Management Techniques for Supporting Real Time Traffic in CDMA Based Wireless Mesh Networks

With the recent advances in the development of wireless communication networks, Wireless Mesh Networks (WMNs) have been receiving considerable research interests in recent years. Many challenges need to be addressed for successful WMN deployment. One of the fundamental challenges is the need to support integrated services and provision different Quality of Service (QoS) for various applications. In order to allow differentiated services, Medium Access Control (MAC) has to provide priority management techniques at the link layer. In Code Division Multiple Access (CDMA) based WMNs, the interference phenomenon and the simultaneous transmissions must be considered. We propose two priority schemes for a distributed CDMA-based MAC WMNs. We take into account interference, multiple services, QoS requirements for each type of traffic, and the simultaneous transmission in CDMA. The first priority scheme is within a node. Each node has independent queues for each traffic class. According to QoS requirements, the queue that should be served first is determined. The second priority scheme is among neighbour nodes. It is proposed for possible multiple simultaneous transmissions with CDMA. This scheme gives a higher chance of correct transmission to high priority traffic than low priority traffic. In addition, we propose to use an adaptive spreading gain and a frame structure to achieve high resource utilization. Simulation results demonstrate that the proposed schemes can achieve effective QoS guarantee