Quadrature modulation for UWB wireless multipath channels

This paper introduces a quadrature pulse amplitude modulation (QPAM) scheme for ultrawideband (UWB) wireless communications by utilizing two orthogonal pulses. An important advantage of QPAM over binary PAM is that it is more power efficient and this is critical in UWB communications. In addition we investigate the use of M-ary binary-coded QPAM signals to further increase the bit transmission rate supported by UWB communication systems. The power efficiencies of bipolar QPAM and M-ary binary-coded QPAM are compared. We also present a comparison of the role of time hopping (TH) and direct-sequence (DS) spreading in providing robust performance in multipath environments for UWB communications.

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