ABSTRACT
In this Letter, we propose a flexible bandwidth compression scheme for visible light communication (VLC) systems employing multi-band carrierless amplitude and phase (CAP) modulation. The scheme combines a narrow filtering for every subband at the transmitter and an N-symbol look-up-table (LUT) based maximum likelihood sequence estimation (MLSE) at the receiver. The N-symbol LUT is generated by recording pattern-dependent distortions induced by inter-symbol-interference (ISI), inter-band-interference (IBI), and the other channel effects upon the transmitted signal. The idea is experimentally demonstrated on a 1 m free space optical transmission platform. The results show that the proposed scheme can improve the subband overlap tolerance up to 42% in subband overlapping scenarios, that is, 3 bit/s/Hz, which is the highest spectral efficiency (SE) among the experimented schemes.
ABSTRACT
Novel photosensitizers beta-(hydroquinon-2-yl)-5,10,15,20-tetra(4-hydroxylphenyl)porphyrinato zinc(II) (Zn(II)P) and beta-(hydroquinon-2-yl)-5,10,15,20-tetra(4-hydroxylphenyl)porphyrinato copper(II) (Cu(II)P) were synthesized and characterized. Their ability of producing singlet oxygen under irradiation was detected by the measurement of decomposition of 1,3-diphenylisobenzofuran (DPBF). The preliminary biological activity studies show that the Zn(II)P has photo-toxicity on human chronic myelogenous leukemia cell (K562) and could cleave supercoiled DNA (pBR 322 DNA), while the Cu(II)P has inferior biological activity. Results showed Zn(II)P having high anti-tumor activity, which presents a promising photosensitizer for photodynamic therapy.
