Author Affiliations
Abstract
Electrical and Computer Engineering Department, University at Albany, New York 12222, USA
A plethora of physical-layer techniques aim to enhance the performance of communication systems in several ways. Spectral efficiency and security are on the top of the list of enhancements; however, both are isolated and antagonistic islands of research. Augmented communication (ACom) is introduced in this Letter as the first technique that aims to combine these two enhancements in visible light communications (VLCs). The dividends of the proposed concept are demonstrated via simulations and the performance is experimentally validated. Results show that ACom can simultaneously provide the high spectral efficiency and the resistance to eavesdropping, while introducing minimal signal-to-noise ratio penalties.
augmented communications orthogonal frequency division multiplexing spectral efficiency physical layer security visible light communications Chinese Optics Letters
2020, 18(9): 090601
Author Affiliations
Abstract
Optical spatial modulation (OSM) is a multiple-transmitter technique that can provide higher data rates with low system complexity as compared with single-input single-output systems. Orthogonal frequency division multiplexing (OFDM) is widely implemented to achieve better spectral efficiency in wireless channels. Asymmetrically clipped optical OFDM (O-OFDM) and DC-biased O-OFDM are two well-known O-OFDM techniques suitable for intensity-modulation direct-detection optical systems. In this work, sample indexed spatial OFDM (SIS-OFDM) is proposed to combine OSM and O-OFDM in a novel way and achieve significant performance gain. By assigning time-domain samples of the O-OFDM transmit symbol to different transmitters, SIS-OFDM achieves much better spectral efficiency and reduces computational complexity at the transmitter as compared with previous work that combines OSM with O-OFDM in the frequency domain. We also consider the impact of optical source biasing on overall performance, and the relative performance of imaging receiver (ImR) versus non-imaging receiver (NImR) design for our proposed SIS-OFDM technique. Results indicate that for an Ntx × Nrx multiple-input multiple-output configuration where Ntx = Nrx = 4, SIS-OFDM using ImR can achieve up to 135 dB of signal-to-noise ratio gain over comparable system using a NImR. Also, using Nsc number of O-OFDM subcarriers provides up to Nsc × log2(Ntx) additional bits per symbol of spectral efficiency over techniques that combine OSM and O-OFDM in the frequency domain.
060.4080 Modulation 060.4230 Multiplexing 060.4510 Optical communications 060.2605 Free-space optical communication Chinese Optics Letters
2014, 12(9): 090602
