Analysis of Nyquist Pulse Shapes for Carrierless Amplitude and Phase Modulation in Visible Light Communications

Abstract

Abstract-This paper proposes and experimentally demonstrates, for the first time, two new candidate pulse shapes for carrier-less amplitude and phase modulation in the context of visible light communications. It is commonly accepted that the pulse shape at the heart of the Hilbert pair used to generate the required orthogonal signal spaces should be the square-root raised cosine. In this work, we introduce two additional candidate pulse shapes, namely the first-order Xia pulse and the socalled better-than-Nyquist pulse. We demonstrate experimentally that the better-than-Nyquist pulse offers superior bit-error rate performance compared to the square-root raised cosine and Xia pulses under additive white Gaussian noise channel conditions, whilst offering lower computational complexity.

Quadrupling the Data Rate for Narrowband Internet of Things without Modulation Upgrade

“…The up-sampled symbols are then filtered by the Hilbert filter pair, giving S 1 and S 2 . The summation of the filtered signals on two paths output the transmitted signal s(t), given by: The Hilbert transform pair, namely the g(t) andĝ(t), are generated by a square root raised cosine (SRRC) pulse p(t) in the proposed system, which is expressed as [19]:…”

Doubling the Rate of Spectrally Efficient FDM Systems Using Hilbert Pulse Pairs

“…Traditionally, a pair of sinusoidal carrier and co-sinusoidal carriers are used to form the Hilbert pair. Subsequently, the impulse response of the shaping pulse filters are the product of the pulse p(t) and the carrier pair of frequency f c , given by [12]:…”

“…The second stage employs time-reversed matched filtering (MF) without the use of advanced detection methods. The matched filtering pair at the first stage can be obtained by flipping the Hilbert pulse pair in the time domain, as given by [12]:…”

“…Advantageously, signals can be generated using a Hilbert pair, which is a pair of pulse shapes that generate orthogonal signals as has been recently utilised in optical carrier-less amplitude and phase Modulation (CAP) [12]. In this work, we propose to couple the Hilbert pair with a SEFDM to improve further bandwidth efficiency relative to conventional SEFDM systems.…”

A 3 × 25 Mbps WDM-Ro-VLC System for Amateur Radio Applications

“…The proposed scheme includes pre-and post-equalizations, micro LEDs, and advanced detection circuits and multi-level and multi-carrier modulations [1][2]. The latter includes single carrier frequency domain equalization, multi-band carrier-less amplitude and phase modulation, orthogonal frequency division multiplexing (OFDM), and OFDM/offset quadrature amplitude modulation [6][7][8][9]. As for modulation schemes used in VLC systems, the multi-level and multi-carrier modulation formats offers increased data rates both implementation but at the cost of increased complexity and cost as well as have a limited peak to average power ration to ensure operation within the linear region of the LED light source.…”