Wideband Impulse Modulation and Receiver Algorithms for Multiuser Power Line Communications
- PDF / 682,445 Bytes
- 14 Pages / 600.03 x 792 pts Page_size
- 109 Downloads / 161 Views
Research Article Wideband Impulse Modulation and Receiver Algorithms for Multiuser Power Line Communications Andrea M. Tonello Dipartimento di Ingegneria Elettrica, Gestionale, e Meccanica (DIEGM), Universit`a di Udine, Via delle Scienze 208, 33100 Udine, Italy Received 8 November 2006; Accepted 23 March 2007 Recommended by Mois´es Vidal Ribeiro We consider a bit-interleaved coded wideband impulse-modulated system for power line communications. Impulse modulation is combined with direct-sequence code-division multiple access (DS-CDMA) to obtain a form of orthogonal modulation and to multiplex the users. We focus on the receiver signal processing algorithms and derive a maximum likelihood frequency-domain detector that takes into account the presence of impulse noise as well as the intercode interference (ICI) and the multiple-access interference (MAI) that are generated by the frequency-selective power line channel. To reduce complexity, we propose several simplified frequency-domain receiver algorithms with different complexity and performance. We address the problem of the practical estimation of the channel frequency response as well as the estimation of the correlation of the ICI-MAI-plus-noise that is needed in the detection metric. To improve the estimators performance, a simple hard feedback from the channel decoder is also used. Simulation results show that the scheme provides robust performance as a result of spreading the symbol energy both in frequency (through the wideband pulse) and in time (through the spreading code and the bit-interleaved convolutional code). Copyright © 2007 Andrea M. Tonello. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1.
INTRODUCTION
The design of broadband communication modems for transmission over power lines (PL) is an interesting and open problem especially with reference to the development of reliable transmission and advanced signal processing techniques that are capable of coping with the harsh properties of the power line channel and noise [1]. In this paper, we deal with advanced signal processing algorithms for a wideband (beyond 20 MHz) impulse-modulated modem [2–4]. Up to date, impulse modulation has only been considered for application in ultra-wideband (UWB) wireless channels [5–7]. It has interesting properties in terms of simple baseband implementation and robustness against channel frequency selectivity and interference. Differently from the wireless context, PL channels have a narrower transmission bandwidth [8] and are characterized by several background disturbances as colored and impulse noise [9]. Nevertheless, wideband impulse modulation is an attractive scheme for application over this medium as experimental trials have shown [4]. The basic idea behind impulse modulation is to convey information by mapping an information symbol stream into a sequence of short-duration pulses. Pulses (ref
Data Loading...