This paper presents a study into different angles for the New spread matrix developed for BSOFDM. It varies the angles for the matrix to develop different constellation schemes which are useful in overcoming the frequency selective channels which are encountered in mobile communication systems. Previously it has been discussed that this new matrix (the rotation matrix) has some advantages over Hadamard and the rotated Hadamard matrix in certain channels. This paper presents a study of varies angles with this new matrix over the UWB channels CM1 to CM4. Disciplines Physical Sciences and Mathematics Publication Details

This paper continues the work on the new Rotation matrix developed for BSOFDM which showed improvement in frequency selective channels such as the UWB IEEE defined CM1 to CM4 and overall system performance. This paper presents a method by which higher order Rotation matrix can be derived and simulation results are used to show that the higher order Rotation matrix outperforms the Hadamard matrix in frequency selective channels. KeywordsRotation spreading matrix, BSOFDM, Frequency selective channel Disciplines Physical Sciences and Mathematics

In this paper, we derive and analyze a companding algorithm based on the hyperbolic tangent and inverse hyperbolic tangent functions for use in orthogonal frequency division multiplexing (OFDM) transceivers. Probability density functions (PDFs) that approximate the transmitted and received OFDM signals in the presence of additive white Gaussian noise (AWGN) are derived and used to analyze the degree of companding relative to the signal-to-noise ratio (SNR) and clipping level. A set of optimal companding linearity coefficients for the multiband OFDM (MB-OFDM) ultra-wideband (UWB) standard are presented. are derived and used to analyze the degree of companding relative to the signal-to-noise ratio (SNR) and clipping level. A set of optimal companding linearity coefficients for the multiband OFDM (MB-OFDM) ultra-wideband (UWB) standard are presented. Disciplines Physical Sciences and Mathematics

This paper investigates inter-piconet interference (IPI) in the multi-band orthogonal frequency division multi-plexing (MB-OFDM) ultra-wideband (UWB) standard. IPI is caused when the time-frequency codes (TFCs) that delineate MB-OFDM piconets collide. An upper-bound on the severity of the IPI problem is obtained through a theoretical analysis of data-rate-specific punctured convolutional codes. Using these results, several methods for adaptive TFCs are proposed and analyzed. Comprehensive simulation results show how packet error rates (PERs) for simultaneous operating piconets (SOPs) can be improved by up to 2 dB by enabling adaptive TFCs at the transmitter. Several combinations of data rate, TFC, channel model and interferer power are studied. Abstract-This paper investigates inter-piconet interference (IPI) in the multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) standard. IPI is caused when the time-frequency codes (TFCs) that delineate MB-OFDM piconets collide. An upper-bound on the severity of the IPI problem is obtained through a theoretical analysis of data-rate-specific punctured convolutional codes. Using these results, several methods for adaptive TFCs are proposed and analyzed. Comprehensive simulation results show how packet error rates (PERs) for simultaneous operating piconets (SOPs) can be improved by up to 2 dB by enabling adaptive TFCs at the transmitter. Several combinations of data rate, TFC, channel model and interferer power are studied. Disciplines Physical Sciences and Mathematics

In this paper we present extremely low-complexity adaptive infinite impulse response (IIR) filters that approximate minimum mean square error (MMSE) channel estimation in orthogonal frequency-division multiplexing (OFDM) systems. We show how the packet error rate (PER) can be significantly improved over conventional zero-forcing (ZF) estimation without incurring a significant increase in computational complexity. All quantitative results are provided in the context of multi-band OFDM (MB-OFDM) ultrawideband (UWB) with standard IEEE channel models. Abstract-In this paper we present extremely low-complexity adaptive infinite impulse response (IIR) filters that approximate minimum mean square error (MMSE) channel estimation in orthogonal frequency-division multiplexing (OFDM) systems. We show how the packet error rate (PER) can be significantly improved over conventional zero-forcing (ZF) estimation without incurring a significant increase in computational complexity. All quantitative results are provided in the context of multi-band OFDM (MB-OFDM) ultra-wideband (UWB) with standard IEEE channel models.