Optical digital pulse-position modulation: experimental results for heterodyne detection using suboptimal filtering

Abstract Visible light communication (VLC) has recently drawn more attention due to the existing light sources having a bandwidth that can deliver data transmission at higher bit rates. To maintain desired brightness levels along with reliable data transmission, VLC requires to control dimming levels. In this paper, a dimming control scheme based on pulse position modulation (PPM) is proposed, which constructs a dimming encoded frame per symbol of input data. The scheme utilizes multiple headers, which is selected depending on the dimming levels and the number of bits in a symbol of input data. The proposed scheme for the VLC system supports various dimming levels. The multi header PPM frame generation for input data K = 4 $K=4$ and dimming values α = 0.25, 0.375, and 0.5 is simulated using NI Labview. The proposed dimming scheme has an excellent short-run length property which is well under the maximum flickering time period and is thus capable of flicker mitigation. The slot error performance of the proposed dimming control scheme in a VLC system for varying dimming levels is simulated in Matlab. Simulation results show that the proposed scheme has excellent error performance for a low dimming value of α = 0.25. The experimental results are also carried out in the optisystem considering the practical measured parameters of the indoor environment for free space channel and simulating the VLC system for the proposed scheme. The simulation is carried for different data rates over varying link ranges and the experimental results show that the proposed scheme performs best when dimming value α = 0.25 and data rate 2 Gbps.

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Fast word synchronisation for digital pulse-position modulation

Electronics Letters ◽

10.1049/el:19990228 ◽

1999 ◽

Vol 35 (4) ◽

pp. 274 ◽

Cited By ~ 1

Author(s):

V. Jungnickel ◽

A. Can ◽

C. von Helmolt

Keyword(s):

Pulse Position Modulation ◽

Digital Pulse

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Research on Modulations of Wireless Optical Communication System Based on RS Code under Weak Turbulence Atmosphere Channel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.4945 ◽

2014 ◽

Vol 556-562 ◽

pp. 4945-4949

Author(s):

Yang Liu ◽

Guoan Zhang

Keyword(s):

Bit Error Rate ◽

Error Rate ◽

Forward Error Correction ◽

Error Rates ◽

Pulse Interval ◽

Pulse Position Modulation ◽

Weak Turbulence ◽

Rate Performance ◽

Free Space Optical ◽

Digital Pulse

The free space optical (FSO) system model is analyzed based on on-off keying (OOK), pulse position modulation (PPM), differential pulse position modulation (DPPM) and digital pulse interval modulation (DPIM) under the weak turbulence atmosphere. To improve the system performance, one effective way is to use forward error correction (FEC).The bit error rate (BER) calculating formula of uncoded system is derived under all above the modulations firstly, then as a benchmark, under the case of independent with identical distribution, the average bit error rates of RS coded system are derived, respectively. Simulations of the average bit error rate performance of these systems are done. Simulation results show that, PPM has the best bit error rate performance, RS coded is efficient to get the code gain and to improve jamming-rejection capability of system.

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