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The ability to achieve a reliable and optimal design of a WBAN communication system relies largely on a thorough understanding of signal propagation through and around the complex human body as a medium, which differs significantly from one person to another. Hence, it is necessary to model the human body of interest in its corresponding environment to have a successful, reliable, and optimal WBAN. In this paper, we provide a path-loss model of the propagation channel medium between a transmitter antenna and a receiver antenna based on multiple experimental measurements. A number of transmit antennas (Tx) are situated on a wearable sensor nodes and spread on different major parts of the human body, while the receiver antenna (Rx) is kept on a sink node in constant proximity to the human body. The Tx and Rx devices communicate using ZigBee technology on 2.45 GHz band. Current literature addressed channel analysis at 2.45GHz around the surface of the body assuming simplified simulation setup or/and overlooking the impact of the indoor office environment. Our contribution in this paper is to investigate 2.45GHz Zigbee statistical path-loss model thoroughly based on realistic setup and using off-the-shelf devices in an indoor office environment. Channel characteristics from the experimental measurements are compared against representative semi-empirical path loss and log-normal shadowing models. [ABSTRACT FROM PUBLISHER]

The recent introduction of femtocells enabled high data rates and better coverage indoors without the need for upgrading the network infrastructure or site establishment. However, Femtocells may suffer from major interference problems due to their dense and ad hoc deployment. In this paper, we propose a frequency assignment optimal scheme for downlink femtocell networks. The algorithm is based on optimization search rather than greedy or heuristic methods. Simulation results show that the proposed scheme outperformed two representative algorithms used for comparison. [ABSTRACT FROM PUBLISHER]

Rate outage probability is an important performance metric to measure the level of quality of service (QoS) in the 4th Generation (4G) broadband access networks. Thus, in this paper, we calculate a closed form expression of the rate outage probability for a given user in a down-link multi-hop OFDMA-based system encountered as a result of links' channel variations. The channel random behavior on different subcarriers allocated to a given user are assumed to follow independent non-identical Nakagami-m distributions. Besides the rate outage probability formulas, we also derive a novel closed form formulas for the moment generating function, probability distribution function (pdf), and the cumulative distribution function (cdf) of a product of independent non-identical Gamma distributed random variables (RVs). These RVs are functions of the attainable signal-to-noise power ratio (SNR) on the allocated group of subcarriers. [ABSTRACT FROM PUBLISHER]