This paper describes a novel modulation scheme for direct sequence ultra-wideband systems (DS-UWB), which have been considered a type of physical layer (PHY) suitable for high-speed wireless personal area networks (WPANs) in IEEE 802.15.3a. In DS-UWB systems, rake reception is essential to capture dispersive energy and to compensate interference generated by multipath fading. Simulation results show that the proposed modulation, named QBOK (quadrature binary orthogonal keying), outperforms the existing 4-ary biorthogonal keying (4-BOK) scheme under multipath environments in terms of bit error rate (BER) whilst allowing more simultaneous users. Additionally, a new correlator and I-Q demodulator structure based on the well-known six-port architecture is described from a theoretical perspective. Additionally, its application as RF frontend in RAKE receivers with analog emphasis is also investigated in this paper, resulting in reduction of the amount of digital signal processing, easing hardware requirements.
['J. Perez-Duenas', 'J.G. Wanguemert-Perez', 'I. Molina-Fernandez']
Novel modulation scheme and six-port based RAKE receiver for DS-UWB