Full Length Research Paper

Energy-efficient channel estimation for multiband UWB systems in presence of interferences

S. M. Riazul Islam* and Kyung Sup Kwak

Telecommunication Engineering Lab, Inha University, Incheon, 402-751, South Korea.

*Corresponding author. Email: riazuldu@yahoo.com.

Accepted 15 November, 2010

Abstract

Interference reduces the performance of a correct data signal detection and decoding. This problem becomes severe when interferences exist during the period of channel estimation. This will destroy the accuracy of channel estimation, and will eventually result to severe degradation in the performance of signal detection and decoding in the entire data packet/frame. In this article, we propose an improved channel estimation technique for multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) system in presence of interferences. In particular, we work towards a preamble-based channel estimation technique in multi-access and narrowband interfering environments. We construct two preamble symbols with opposite, both in amplitude and phase, sequences in frequency-domain. Time-domain redundancy is introduced into these preamble symbols before transmission. Based on this time-domain redundancy property, we eliminate multi-access interference (MAI) through an adaptive select and replace (ASR) scheme. We show that the use of opposite sequences in preambles leads a simple addition, subtraction and compare (ASC) scheme to cancel narrowband interference (NBI). In addition, we apply a frequency-domain filter, driven by channel’s power delay profile (PDP), to get a further enhancement in the estimation accuracy. Simulation results urge that our proposed technique outperforms the conventional channel estimation methods.

Key words: Ultra-wideband, channel estimation, channel impulse response (CIR), multiband orthogonal frequency division multiplexing, wireless personal area network (WPAN), narrowband interference, multi-access interference, and ECMA-368.