Advanced Impulse Radio Techniques

Abstract

In Chap. 3 impulse radio was defined and various modulations and a multiple access scheme were described. There are, however, a few shortcomings associated with these schemes. First, the power spectral density (PSD) of IR could be undesirable. For instance, TH-OOK spectral spikes could interfere with other spectrum users. Secondly, the IR performance in multipath fading could be poor. Multi-path fading channel model can be incorporated into the receiver to improve performance. Thirdly, the existing schemes do not provide a trade-off between performance and complexity. To address these issues some advanced techniques are introduced here. Initially, power spectrum of IR signal is determined and techniques to mitigate PSD are discussed. Then for operation in multipath environments rake receiver and transmitted reference (TR) modulation are proposed and studied. Next a scheme known as dual format modulation (DFM) that accommodates both simple and complex demodulators is described and its performance is evaluated. Lastly, three IEEE 802.15.4a, IEEE 802.15.6 and IEEE 802.15.4f standards that utilize various forms of impulse radio are described in some details.