F. Ramirez-Mireles

On the performance of ultra-wide-band signals in Gaussian noise and dense multipath

An ultra-wide-band (UWB) signal is characterized by a radiated spectrum with a very wide bandwidth around a relatively low center frequency. In this paper, we study the reduced fading margin property of UWB signals. To evaluate the fading margin, we compare the performance of UWB signals in an environment with only additive white Gaussian noise (AWGN) versus the performance of UWB signals in a dense multipath environment with AWGN. The assumption here is that the presence of multipath causes a small increase in the signal-to-noise ratio required to achieve reasonable levels of bit error rate. A numerical example confirms this assumption, more specifically, the example shows that to achieve a bit error rate equal to 10/sup -5/, we require about 13.5 dB in the AWGN case and about 15 dB in the multipath case, resulting in a fading margin of just 1.5 dB. This small fading margin can be understood by the ability of the UWB signal to resolve the dense multipath.

Multiple-access performance limits with time hopping and pulse position modulation

The use of spread spectrum time hopping in combination with pulse position modulation for multiple access communications is studied. The multiple access performance is described in terms of the number of users supported by the system for a given bit error rate and bit transmission rate. Expressions for the maximum number of users and maximum transmission capacity in bits per second are found. Asymptotic values for these quantities are derived.

Multiple-access with time hopping and block waveform PPM modulation

The use of time-hopped block waveform encoding PPM signals sets for multiple access communications is studied. The multiple access performance is analyzed in terms of the number of users supported by the system for a given bit error rate and bit transmission rate. The analysis shows that this technique is potentially able to provide multiple-access communications with a combined transmission capacity of over 500 Megabits per second at bit error rates in the range 10/sup -4/ to 10/sup -8/ using receivers of moderate complexity.

System performance analysis of impulse radio modulation

We present a system performance analysis of impulse radio modulation using block waveform encoding signal sets. We analyze both the multiple-access performance in a channel with additive white Gaussian noise, and the single-link performance in a channel with dense multipath.

Ultra-wide bandwidth (UWB) signal propagation for outdoor wireless communications

Ultra-wide bandwidth (UWB) signal propagation experiment is performed in a rural terrain to characterize the outdoor UWB signal propagation channel. The bandwidth of the signal used in this experiment is in excess of one GHz. The test apparatus and measurement technique are described. From the measured pulse response the mean delay, delay spread, propagation loss and forestation loss are determined.

Signal design for ultra-wide-band communications in dense multipath

Ultra-wide-band (UWB) wireless communications utilizes information signals characterized by a radiated spectrum with a very wide bandwidth around a relatively low center frequency. We formulate the signal design for binary UWB communications taking into consideration the particular characteristics of UWB propagation in a dense multipath channel.

Performance of equicorrelated ultra-wideband pulse-position-modulated signals in the indoor wireless impulse radio channel

Impulse radio (IR) is a spread spectrum (SS) wireless technique in which ultra-wideband (UWB) communication waveforms that consist of trains of time-shifted subnanosecond pulses are modulated to convey information exclusively in the relative time position of the pulses. In this paper we describe the construction of equally correlated (EC) pulse position modulation (PPM) signals, using trains of binary time-shift-keyed UWB subnanosecond pulses. The performance of the EC UWB PPM signals in the indoor IR channel with detection using a Rake receiver is analyzed.

Signal selection for the indoor wireless impulse radio channel

In this paper we investigate communications using quaternary pulse position data modulation over the indoor impulse radio multiple access channel disturbed with multipath. The performance of four quaternary signal sets with different correlation properties is assessed.

Performance of ultra-wideband time-shift-modulated signals in the indoor wireless impulse radio channel

Impulse radio (IR) is a spread spectrum (SS) wireless technique in which ultra-wideband (UWB) communication waveforms that consist of trains of time-shifted sub-nanosecond pulses are modulated to convey information exclusively in the relative time position of the pulses. We make an assessment of the performance of non-binary IR modulation in the presence of multipath with detection using a RAKE receiver.

Signal design for ultra wideband PPM communications

Ultra wideband (UWB) wireless communications utilizes information signals characterized by a radiated spectrum with a very wide bandwidth around a relatively low center frequency. In this work we formulate the signal design for binary UWB pulse position modulated (PPM) communications taking into consideration the particular characteristics of UWB propagation in a dense multipath channel.