Department Publications

Vehicular ad-hoc networks (VANETs) play a vital role in enabling intelligent transport services (ITS). The state of art dedicated short range communication (DSRC), which is envisioned to facilitate the communication in VANETs, requires dedicated hardware. This hinders the penetration of ITS especially in developing countries. This paper studies the suitability of Wi-Fi Direct (WD), which is readily available on many smart phones, as an alternative communication technology for VANETs. Performance measures such as throughput, end-to-end delay, packet receiving/loss ratios for both WD and DSRC are presented through simulations, using network simulator NS3, and the traffic simulator Simulation of Urban Mobility (SUMO). Both single-hop and multi-hop communication is considered. The results show the potential of WD as an alternative communication technology for VANETs.

Visible Light Communication (VLC) is emerging as a next generation data transmission method for short-range communication applications. In this paper we implement and characterize two prototype stereo audio streaming methods utilizing VLC. A software architecture is developed to process and stream data. The software architecture is bridged with a hardware section, which facilitates free-space VLC channel, over a Universal Serial Bus (USB) to serial interface. A particularly attractive feature of our system is that it uses commonly available, low-cost components which enables its implementation in everyday applications.

This paper introduces a model to study both single tier and multitier wireless communication systems consisting of a multitude of wireless access points (AP), and operating according to the classical opportunistic beamforming framework. The AP locations in the proposed network model are determined by using planar Poisson point processes. The extreme value distribution of signal-to-interference-plus-noise-ratio (SINR) on a beam is of fundamental importance for obtaining performance bounds for such an opportunistic communication system. Two tight distribution approximation results are provided for the distribution of maximum SINR on a beam, which is hard to obtain due to correlation structure of the underlying inter-AP interference field, using key tools from stochastic geometry. These approximations hold for general path loss models that satisfy some mild conditions. Simulations and numerical evaluations …

Multiple antenna techniques, that allow energy beamforming, have been looked upon as a possible candidate for increasing the efficiency of the transfer process between the energy transmitter (ET) and the energy receiver (ER) in wireless energy transfer. This paper introduces a novel scheme that facilitates energy beamforming by utilizing Received Signal Strength Indicator (RSSI) values to estimate the channel. Firstly, in the training stage, the ET will transmit sequentially using each beamforming vector in a codebook, which is pre-defined using a Cramer-Rao lower bound analysis. The RSSI value corresponding to each beamforming vector is fed back to the ET, and these values are used to estimate the channel through a maximum likelihood analysis. The results that are obtained are remarkably simple, requires minimal processing, and can be easily implemented. Also, the results are general and hold for all …

We present the development and testing of a cellular network built on open source technologies. This network supports voice calls and text messages within the network or between networks. The main objective of this work is to develop a stand-alone mobile network consisting of one base station and a switch, the access to which can be controlled as required. The mobile network is also connected to public networks. The designed network is based on Global System for Mobile Communications (GSM). Our work includes the configuration of the embedded hardware components, selection and integration of the proper software combination, testing of compatible versions of the software, hardware-software integration within the embedded system, and interconnecting the systems via the Internet. The key contribution and novelty of the project is the development of a stand-alone mobile network base station/ switch …

The achievable average rate of a full-duplex (FD) multiple-input-single-output interference channel with linear transceiver structures is analyzed. The impact of transmit front-end noise is included in the analysis. Both cooperative and non-cooperative strategies for the FD interference channel are considered and the closed-form expressions are derived for the achievable average rate of each strategy.