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Following FCC approval of ultra-wide band (UWB) radio rules for commercial applications in 2002, a UWB radio physical layer standard is currently under development. Although the UWB transmitting UWB band are spelled out by the FCC, neither UWB signal forms nor modulation schemes are defined by the regulations, stated in ref. [1]. This paper presents the models of two types of impulse radio UWB modulation systems and their simulation performance. They are direct sequence UWB (DS-UWB) and time hopping UWB (TH-UWB). Unique ways of modulating and positioning the impulses, as in transmitted-reference delay (TRD) modulation and pulse-position modulation (PPM) , can result in the simple UWB radio architectures. Systems of TRD for DS-UWB and PPM for TH-UWB are simulated under the same UWB working data rate and under the same AWGN (additive white Gaussian noise) channel conditions. The simulation shows that DS-TRD system presents superior performance over PPM-TH system, which is shown in the comparison chart of the paper. The simulation was verified with ideal calculated performance for DS-TRD modulation. The UWB applications are also discussed in the paper. The original manuscript of the findings in the paper is published in the conference ref. [2]. [ABSTRACT FROM AUTHOR]

M-ary baseband FSK modulated signals, which utilize M-set different frequencies, can be modelled as a set of complex rotating phasors. The received modulated signals can be detected by counting the speed and the direction of the complex phasor rotation. Conventional methods such as zero-crossing detection used this baseband FSK signal property. The detection approach presented in this paper is to count the number of quadrant crossing instead of zero crossing in a symbol period to demodulate FSK signals. Counting quadrant crossings acts as a noise filtering and improves the detection performance. The performance is improved further by using decision rules at fuzzy boundary and soft decision detection. The system modelling and simulation methods are illustrated in the paper. The performance comparison and improvement are shown by a 4-ary FSK signal example on wireless Rayleigh fading channels. [ABSTRACT FROM AUTHOR]