Abstract
In this paper, we experimentally demonstrate the performance of a non-orthogonal multi-band super-Nyquist carrier-less amplitude and phase (m-SCAP) modulation for visible light communications (VLC). We break the orthogonality between sub-bands in the frequency domain by compressing the spectrum, purposely overlapping them, and introducing inter-band interference (IBI). We demonstrate that our proposed system can tolerate IBI, and hence spectral efficiency can be increased without introducing additional complexity to the receiver. We show that m-SCAP can tolerate up to 30% and 20% compression for 4- and 16-level quadrature amplitude modulation, respectively, thus leading to an improvement in spectral efficiencies up to 40% and 25%, respectively, at the cost of bit error rate performance, which however remains below the 7% forward error correction limit. Moreover, the experimental results are supported by numerical simulations.
Highlights
The need for communication systems using modulation schemes that offer high spectral efficiency is evident especially due to the ever-increasing end-user demands for high-speed data services [1]
In order to validate the experimentally measured bit-error rate (BER) results, we carried out a numerical simulation in MATLAB, which used the measured system responses (i.e. L-I-V curve and the bandwidth as given in [7], as well as the signal-to-noise ratio (SNR) of ∼ 19.5 dB measured experimentally)
Higher multi-band super-Nyquist carrier-less amplitude and phase (m-SCAP) (i.e., ≥ 8) can support α of 30%, which corresponds to a saving in the bandwidth of 900 kHz
Summary
The need for communication systems using modulation schemes that offer high spectral efficiency is evident especially due to the ever-increasing end-user demands for high-speed data services [1]. The same idea has been translated into the timedomain in the form of faster-than-Nyquist signalling [18], where an improvement in spectral efficiency is achieved by intentional aliasing of pulse shaping filters at the cost of introducing inter-symbol interference (ISI) In these systems, knowledge of the interference characteristics allows amelioration of interference effects at the receiver and in SEFDM this has resulted in the demonstration of systems that can increase throughput by up to 60% with a tolerable loss of performance [19,20,21,22]. The results are demonstrated experimentally and validated by numerical simulations
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