Generation of multiple orthogonal pulses and indoor channel modeling under consideration of ultra-wideband system restrictions

Abstract

Impulse Radio Ultra-wideband (IR-UWB) technology has been considered as a promising candidate for short-range indoor wireless communications. Due to the characteristic of extremely broad bandwidth, the regulations of considerate system have been existed such as pulse shape design to meet the spectral mask and reducing processing burden for practical implementation. In this paper, we propose the practical pulse shape design strategy and efficient low complexity channel modeling method in consideration of those UWB system restrictions. The pulse shape of UWB system needs to be judiciously designed in order to coexist with other narrow band systems and to meet the requirements on the power spectral mask defined by Federal Communications Commission (FCC) and the IEEE 802.15.4a standard. However, most of the research on pulse shape has focused on meeting the FCC spectral mask, while few studies have been conducted to satisfy the IEEE 802.15.4a standard. For orthogonal pulses which are often required for high-rate modulation, meeting both constraints becomes challenging. Therefore, in this letter, we propose a novel strategy to generate multiple orthogonal pulses taking both of the IEEE 802.15.4a and the FCC constraints into consideration. The modified root-raised cosine (MRRC) pulse is developed as a single pulse satisfying both constraints. By modulating the MRRC pulse with orthogonal bases generated by the Gram-Schmidt orthonormal process, the multiple pulses are established. In order to maintain the orthogonality of proposed multiple pulses at the receiver, we proposed a orthogonal design method using the QR decomposition method. The performance analysis is also presented with mathematical derivations and numerical simulations to show that the proposed pulses can be utilized for higher data rate or lower error rate. In indoor localization application using UWB signal, the accurate measurement and channel modeling in UWB system also need to estimate the accura...