Wireless voice over internet protocol (VoIP) is an important emerging service in telecommunication due to its potential for replacing cell phone communication wherever a wireless local area network (WLAN) is installed. Recent studies, however, suggest that the number of voice calls that can be supported in the widely deployed IEEE 802.11 WLAN is limited. In this paper, we utilize a so-called tr...

One of the major constraints in wireless sensor networks (WSNs) is power consumption. In recent years, a lot of efforts have been put into the design of medium access control (MAC) protocols for WSN, in order to reduce energy consumption and enhance the network’s lifetime. In this paper, we surveyed some MAC protocols for WSN and compared their design tradeoffs. The goal is to provide a foundat...

Contributing to previous research that has identified differences in connection speed, user skill, and experience as mechanisms affecting digital divides among Internet users, this paper explores whether location of use should be considered a factor that limits or facilitates individual efforts to apply the Internet toward beneficial activities. At some locations, Internet users enjoy high leve...

The use of smart antennas in extending coverage range and capacity of wireless networks dictates the employment of novel media access control protocols, with which the base station (BS) or access point (AP) provides access to users by learning their locations. We consider the class of protocols that employ beamforming and use contention-based or contentionfree polling methods to locate users re...

In energy harvesting IoT networks, an energy queue state of an IoT device will change dynamically and the number of IoT devices that transmit data to the IoT AP will vary in a frame. So we need a MAC protocol to adjust the frame length taking the amount of energy of IoT devices into consideration. Since the existing Framed slotted ALOHA (F-ALOHA) Medium Access Control (MAC) protocol utilizes th...

Circularly polarized antennas are used in 2.4 GHz ZigBee radio modules to evaluate performance improvement of RSSI (Received Signal Strength Indicator) based location techniques, with respect to conventional linearly polarized antennas. Experimental RSSI measurements in an indoor environment clearly show that multipath fading is significantly reduced when CP antennas are used; this determines a...

Applications over Wireless Sensor Networks (WSNs) are various and different. Many routing protocols have been proposed for WSNs since a many years. Medium Access Control (MAC) protocols can differ from a network to another. The transmission range can also be variable from a sensor to another depending on their battery capacities. All these various protocols have an influence on the WSNs. It is ...

We present a mathematical model to study decentralized detection in clustered wireless sensor networks (WSNs). Sensors and fusion centers (FCs) are distributed with the aim of detecting an event of interest. Sensors are organized in clusters, with FCs acting as cluster heads, and are supposed to observe the same common binary phenomenon. A query-based application is accounted for; FCs periodica...

We propose a network implementation with enhanced security at the physical layer by means of time-hopping CDMA, supporting cryptographically secure point-to-point and point-to-multipoint communication. In particular, we analyze an active star topology optical network implementation capable of supporting 128 simultaneous users up to 20 km apart. The feasibility of the proposed scheme is demonstr...

With the developments of mobile communication, networks and information technology, many new information service patterns and dissemination modes emerge with some security and privacy threats in access control, i.e., the ownership of data is separated from the administration of them, secondary/mutiple information distribution etc. Existing access control models, which are always proposed for so...