In this paper, we present a method to obtain a set of orthogonal pulses to be used in pulse-shape modulation (PSM) for ultra-wideband communications. The pulses are built as linear combinations of Hermite functions, which are shown to have unique advantageous features. Mathematical restrictions of orthogonality and spectral efficiency are introduced as guidelines to a fully explained search procedure to find the best set of pulses. Additionally, this procedure is adapted and used to find a single FCC-compliant pulse shape. A quaternary PSM scheme is implemented with orthogonal pulses obtained by the proposed method, and the results of a simulation are shown
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"Several modulation schemes such as pulse position modulation (PPM) (Win and Scholtz, 1998), pulse shape modulation (PSM) (da Silva and de Campos, 2002 de Campos, , 2007), and combinations of them (Mitchell et al., 2003; da Silva and de Campos, 2003) are proposed for UWB transmission. Time-hopping pulse position modulation (TH-PPM) scheme utilises Gaussian monocycles as the transmitted pulse shape (Win and Scholtz, 2000). "
[Show abstract][Hide abstract]ABSTRACT: Choice of ultra wideband (UWB) pulse shapes has become an interesting challenge such that the spectral limits of the frequency band approved by the Federal Communications Commission (FCC) can be utilised efficiently. In this paper, we compare the efficiency of various UWB pulse shapes based upon their power spectral density (PSD) and autocorrelation functions (ACF). We propose a set of prolate spheroidal wave functions (PSWF) for a typical M-ary pulse shape modulation (PSM) scheme. In the process, we show closed form expressions for the ACF of PSWF-based UWB pulse shapes of different orders.
Full-text · Article · Jan 2014 · International Journal of Ultra Wideband Communications and Systems
"As it is stated, the method that is proposed in  for the design of the timeorthogonal shaping filters guarantees that all of them have the same time-duration and (practical) bandwidth . Although the time-orthogonal filter design in  was proposed for Ultra Wide Band systems, the authors show in  that the time-duration and bandwidth of the filters can be adequately scaled for narrowband systems, and so the same design can be used. Hence, the time-orthogonal shaping filters can be designed to have the same bandwidth requirements as a single filter narrowband system. "
[Show abstract][Hide abstract]ABSTRACT: In this article, we propose a closed-loop precoding method for the Generalized Space Shift Keying (GSSK) modulation scheme, suitable for Multiple-Input-Single-Output (MISO) systems and denoted as adaptive GSSK (AGSSK), which achieves transmit-diversity gains in contrast to GSSK. For the case of a perfect feedback channel, we analytically show that for three and four antennas at the transmitter and rates 1 and 2 bits per channel use (bpcu), respectively, a full transmit-diversity can be achieved without reducing the achievable rate. For higher number of transmit antennas and rates, the performance of the proposed scheme degrades due to the smaller average minimum Euclidean distance as the rate increases. Due to this, we, furthermore, propose an enhancing method for AGSSK which relies on the use of time-orthogonal shaping filters for the different constellation points. For the enhanced method, named as AGSSK with time-orthogonal signal design (AGSSK-TOSD), we analytically prove that it offers transmit-diversity gains which are greater than the number of active transmit antennas for any number of transmit antennas and supported rate. This is attained without any antenna subset selection technique, which alleviates the processing burden on the terminal side. Monte Carlo simulations show that AGSSK significantly outperforms GSSK in terms of average bit error probability (ABEP) and, moreover, for medium to high rates and practical signal-to-noise ratio (SNR) regions AGSSK-TOSD outperforms well-known feedback-based multiple-antenna schemes. This advantage of AGSSK-TOSD is further substantiated with an energy effficiency comparison over the conventional schemes for a target (uncoded) ABEP.
Full-text · Article · Feb 2013 · EURASIP Journal on Wireless Communications and Networking
"A number of design approaches such as modified Hermite pulses (MHP) are proposed as UWB pulses those are orthogonal with short time duration, and are derived by successive differentiation of Gaussian shaped pulses , . Pulse shape modulation (PSM) utilizes the spectral efficiency of UWB pulses ,  in UWB impulse radio (IR) transmission scheme. The underlying idea is to represent the symbols with a set of orthogonal pulses resulting in an M -ary PSM . "
[Show abstract][Hide abstract]ABSTRACT: Ultrawideband (UWB) pulse shapes based on modified Hermite pulses (MHP) are considered to be good candidates to meet Federal Communications Commission (FCC) regulations. In this paper, we present an analysis of power spectral density (PSD) and autocorrelation function (ACF) of MHP. The properties of ACF and PSD are discussed as an application in an M-ary pulse shape modulation scheme.