Cross-modulation interference for pulse position modulated UWB signals

The detection issues of UWB signals depend on the type of modulation scheme used during the transmission. The cross-modulation interference (CMI) for pulse position modulated (PPM) UWB signaling is introduced. The effects of CMI on the detection mechanism of selective-Rake (SRake), transmitted-reference (TR) and energy detector (ED) receivers are analyzed. The bit-error-rate (BER) performance of all three receivers in the presence and absence of CMI are studied through computer simulations. The results show that the CMI amount varies according to the modulation index and the performance degradation due to CMI can be extremely severe depending on the modulation index for all three receivers. The validity of the conventional optimal and orthogonal PPM criteria are checked considering the CMI effects. The results demonstrate that the conventional orthogonal PPM for all three receivers and the conventional optimal PPM criterion for N-SRake and TR receivers can be used in the presence of CMI. On the other hand, the BER performance of ED receivers using the conventional optimal PPM criterion result in error floor and this criterion is not valid to be used for ED receivers