UDC 621.371
BANDWIDTH CAPACITY OF UNDERWATER WIRELESS OPTICAL TELECOMMUNICATION CHANNEL WITH PULSE-CODE MODULATION BY INTENSITY
S. N. Kirillov, Dr. Sc. (Tech.), full professor, Head of the Department, RSREU, Ryazan, Russia;
orcid.org/0000-0002-3673-5709, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
L. V. Aronov, Senior lecturer, RSREU, Ryazan, Russia;
orcid.org/0000-0001-9010-3836, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Underwater wireless optical communication channel capacity with pulse-code modulation by intensity (PCM) is estimated. The aim is to substantiate signal statistical model at receiver photodetector output of underwater wireless optical communication channel, taking into account the internal noise of photosensitive element, as well as to assess the feasibility of using correction codes. The statistical characteristics of optical receiver photodetector noise designed to operate as part of underwater wireless optical (laser) communication channel are considered. The statistical model is substantiated and the channel capacity is determined in absence and presence of Reed-Solomon code. The form of probability density function has been substantiated and the statistical characteristics of additive noise as well as the mixture of noise and useful signal have been calculated. The probabilities of binary signal reception error during PCM modulation in underwater wireless optical communication channel are obtained; the results have shown that at a distance of 10 to 100 m the probability of erroneous reception is from 0,23·10-9 to 4,2·10-1 s with high detection threshold from 1 to 0,056 μA and channel bandwidth from 100 to 1000 MHz. With given channel parameters and transmitter power of 0,1 W, it is possible to ensure the operation of optical communication channel in clear sea, at the distance of up to 100 m, with 1,6 MHz bandwidth and error probability per binary symbol of no more than 10-6. Using Reed-Solomon correction code with code rate of 0.143 data transmission range is increased by 115 % for 100 MHz bandwidth and by 34 % for 1 GHz bandwidth.
Key words: underwater optical wireless communication channel, optical communication, free space optical channel, mathematical model, underwater communications systems.