Linear combination of pulses for coexistence in the IEEE 802.15.4a standard

The low data rate, accurate location-ranging wireless personal area network (WPAN) standard IEEE 802.15.4a, which is based on ultra-wideband (UWB) impulse radios, suggests using linear combination of pulses to reduce interference to coexisting primary systems. In this paper, we consider possible implementations of linear combination of pulses as suggested in the standard, and study the generated notches in the resulting code spectrum. Using the z-transform approach, we show that the number of these notches is limited and the notch locations are not flexible due to the limited number of pulses allowed by the standard. We also make some suggestions for increasing the number of notches at desired frequencies.