Erry Gunawan

Modeling of transfer Characteristics for the broadband power line communication channel

This paper presents a novel approach to model the transfer function of electrical power lines for broadband power line communication. In this approach, the power line is approximated as a transmission line and the two intrinsic parameters, the characteristic impedance and the propagation constants, are derived based on the lumped-element circuit model. Using these intrinsic parameters, the transfer characteristics for a N-branch power distribution network are derived based on the scattering matrix method. Detail derivation of this line model is given in this paper. The model has been verified with practical measurements conducted on actual power networks. It is demonstrated that the model accurately determine the line characteristics under different network configuration and when different household appliances are connected.

Performance analysis of OFDM systems for broadband power line communications under impulsive noise and multipath effects

The impulsive noise and multipath effects are the main reasons to cause bit errors in power line communications. In this paper, the bit error rate (BER) performance of the orthogonal frequency division multiplexing (OFDM) system under the impulsive noise and multipath effects are theoretically analyzed in terms of closed form formulas. Through the analysis, it is shown that OFDM can mitigate the adverse effect of the impulsive noise and only the heavily disturbed impulsive noise will interfere the BER performance of the OFDM system. It is also shown that the adverse effect of multipath is more serious than that of impulsive noise. In this paper, the guard interval is used to improve the BER performance of the OFDM system. As the longer guard interval is inefficient in using the signal power, the optimum guard interval that can achieve the best BER performance is studied.

A transmission line model for high-frequency power line communication channel

This paper presents a novel approach to modelling the transfer function of the broadband power line communication channel. In the approach, the power line is firstly approximated as a two-wire transmission line. The two intrinsic line parameters, the characteristic impedance and the propagation constant, are derived based on the transmission line theory. Then from the derived line parameters, an echo-based model is used to determine the transfer function for communication signals in the frequency range of 1 MHz-30 MHz. This approach reaps the advantages of accuracy and simplicity of the conventional modeling approaches.

Cooperative Communications in Ultra-Wideband Wireless Body Area Networks: Channel Modeling and System Diversity Analysis

In this paper, we explore the application of cooperative communications in ultra-wideband (UWB) wireless body area networks (BANs), where a group of on-body devices may collaborate together to communicate with other groups of on-body equipment. Firstly, time-domain UWB channel measurements are presented to characterize the body-centric multipath channel and to facilitate the diversity analysis in a cooperative BAN (CoBAN). We focus on the system deployment scenario when the human subject is in the sitting posture. Important channel parameters such as the pathloss, power variation, power delay profile (PDP), and effective received power (ERP) crosscorrelation are investigated and statistically analyzed. Provided with the model preliminaries, a detailed analysis on the diversity level in a CoBAN is provided. Specifically, an intuitive measure is proposed to quantify the diversity gains in a single-hop cooperative network, which is defined as the number of independent multipaths that can be averaged over to detect symbols. As this measure provides the largest number of redundant copies of transmitted information through the body-centric channel, it can be used as a benchmark to access the performance bound of various diversity-based cooperative schemes in futuristic body sensor systems.

Opportunistic routing for body area network

Wireless body area network (WBAN) is an interesting application of sensor networks which can revolutionize our interaction with the outside world. WBAN like any other sensor network suffers limited energy resources and hence preserving the energy of the nodes is of great importance. Unlike typical sensor networks WBANs have few and dissimilar sensors. In addition, the body medium has its own propagation characteristic which means that the existing solution for preserving energy in wireless sensor networks might not be efficient in WBANs. The quality of the links between the nodes in WBAN is changing frequently due to the moving nature of the body. This can pose a major problem especially in the energy efficiency merit. In this work we have proposed an opportunistic scheme to exploit the body movements during the walking to increase the life time of the network. The results show that comparing to the existing methods this work can increase the life time of the network.

Pulse Design for Time Reversal Method as Applied to Ultrawideband Microwave Breast Cancer Detection: A Two-Dimensional Analysis

We conduct a two-dimensional study of pulse design for electromagnetic time-reversal (TR) imaging as applied to ultrawideband (UWB) breast cancer detection. We consider the situation when a tumor located in the human breast is surrounded by a large number of small tissue inhomogeneities that create strong signal clutter. When applying the TR algorithm, the excitation pulse should be properly designed such that there are distinguishable differences between the tumor and clutter responses. In this paper, we propose four pulse design criteria for the TR-based tumor detection. The modulated and modified Hermite polynomials (MMHPs) that fit well into the real pulse shapes are used as a general waveform template for the design process. Finally, numerical examples are used to demonstrate the usefulness of the proposed analytical framework. This paper can be a guide in the selection of suitable waveforms for which the tumor response can be enhanced and/or the clutter interference can be suppressed. The investigation is also well suited for applications to surface-penetrating radar using UWB signals

Development of a test bed for high-speed power line communications

This paper presents the development of a power line test bed which provides a platform to simulate the 230 V power line environment in a controlled and reproducible manner. The target is to communicate data reliably over power lines at speeds of at least 1 Mbits/s with frequency ranging from 1 MHz to 10 MHz. This test bed is integrated with a power line communication channel, power line couplers, loads and impairment devices for worst case environment simulation. A method for coupling the high-frequency signal onto and from the power line is discussed. The design of digital filters for transceivers using advanced digital signal processing techniques is presented. The digital filters are used to amplify, condition and recover the high-frequency signals which have been attenuated and corrupted by noise at the channel.

UWB Microwave Imaging for Breast Cancer Detection --- Experiments with Heterogeneous Breast Phantoms

The paper describes pulse-based ultra-wideband (UWB) radar microwave imaging experiments for breast cancer detection using breast phantoms with dielectric properties mimicking the human breast. Three homogeneous and seven heterogeneous breast phantoms are designed with a series of dielectric permittivity and variability and are used in tumor detection experiments. The experiments are conducted in time-domain with pulse generator and real-time oscilloscope.

HOMOGENEOUS AND HETEROGENEOUS BREAST PHANTOMS FOR ULTRA-WIDEBAND MICROWAVE IMAGING APPLICATIONS

The paper discusses fabrication of homogenous and heterogeneous breast phantoms to simulate the dielectric properties of human breast over the microwave frequency range from 0.5GHz to 13.5GHz. The breast phantoms have stable mechanical conflguration and dielectric properties suitable for microwave imaging experiments particularly ultra-wideband microwave imaging for breast cancer detection.

Performance study of close-loop power control algorithms for a cellular CDMA system

Performance of a reverse link code-division multiple-access (CDMA) system with fast close-loop power control algorithms is studied. It is found that if the fast close-loop power control algorithm functions effectively, the speed of the mobile unit is in the range such that its Doppler frequency is less than one tenth of the power control updating rate. This paper also proposes a new predictive power control algorithm with better performance in terms of system capacity than the conventional and adaptive step size algorithms. An increase in system capacity as high as 22% compared with the conventional algorithm can be achieved depending on the mobile velocity.