OPTICALCOMMUNICATIONPPT BHUVANA

8/6/2019 OPTICALCOMMUNICATIONPPT BHUVANA

http://slidepdf.com/reader/full/opticalcommunicationppt-bhuvana 1/22



Presented by,

R.BHUVANESHWARI S.S.MANOVIDHYAA

3RD ECE 3RD ECE

[email protected] [email protected]



ABSTRACT Underwater Monitoring, Observing systems -

underwater wireless comm. , sensor n/w.

Providing high data rate.

Communication performance with absorption

Alternative to overcome acoustic comm. The link models



INTRODUCTION

PROPERTIES OF UNDERWATER W/L OPTICAL

COMMUNICATION

COMMUNICATION LINK MODELS

BER CALCULATION

NUMERICAL EXAMPLES CONCLUSION



Acoustic underwater communication.

Data rates.

Speed of acoustic waves in ocean-1500 m / s.

Distresses to marine mammals due to acoustic waves.

alternative means of underwatercommunication.

Examples- UUVs and other network controlsystems.





Light pulse-attenuation-wavelength

The extinction co-eff icient[e.o.e]

c(e) = (a) + 3(s)

extinction coeff icient c(e)

Absorption(a) Scattering coeff icients3(s)



Absorption, scattering, and extinction

coeff icients for four types of water such as pure sea water,

clean ocean water,

coastal ocean water, and

turbid harbor water at

520-nm wavelength.

Turbidity e.o.e

The propagation loss



The line-of -sight communication

linkThe modulating retro ref lector

communication link

T

he ref le

cti

on

communi

cati

on link





� Most common link btwn two pts.

� Light beam from transmitter to receiver

� Signal reaching receiver

PR los = PT T RLpr .,(d/ cosx) ( ARec cos x)/{ 2 d 2(1 cos x}

PT Avg. transmitter optical power

T,R-Optical efficiency of the transmitter, receiverd- perpendicular distance btwn. receiver

transmitter

x- laser beam divergence angle



One has high resources than other

e.g.: submarine, diver Interrogator illuminates modulating retro

ref lector by continuous wave beam

Receiver Ref lects with modulatedinformation



If LOS not available

Transmitter emits light wave by 0min, 0max,0i,0t

light reaching ocean-air surf ace bounce back

Ref ractive index<waterTIR

Anular area

Aann = 2 (h + x ) 2(1 cos 0max 1+

cos0min)= 2 (h + x )2(cos 0min cos 0max) Received power

P R ref(0) ARec f Rref(0)



simple, widespread technology

intensity modulation, OOK Receiver based on SiMPs

photo detector f abricated- form of

arrays of photodiodes operated inGeiger mode to create a photon-

counting device.



Accoding to poisson,gaussian distribution

BER = 1/ 2 erfc r1T-r0T

Ertc ( j) =2/j exp (-2)d

Where,r 1 = r d + r bg + r s

r 0 = r d + r bg

rd,rbg-sources of additive noise due to dark

counts and background illumination



LINK PHOTONS

LOS 8000

REFLECTIVE 10RETRO

REFLECTIVE

2



LINK DISTANCEREFLECTIVE 40m

RETRO

REFLECTIVE

50m

LOS 60m



(a) when only

absorption isconsiderers

(b) when absorptionand scattering are

considered



High data rate

Mesg. transmission long distance-multiple relaynode

Hybrid An improvement

Acoustic-low data rate-high turbidity,distance

Optic-high data rate

Complexity ,cost increases In Future more accurate numerical results

Design multiple access, WDM, CDMA



S. Arnon and D. Kedar, Non-line-of sight underwater optical wire-lesscommunication network, J. Opt.

Soc. Am. A 26(3), 530539(2009)

B. Cochenour, L. Mullen, and A. Laux,Spatial and temporal dispersion in

high bandwidth underwater lasercommunication links, inPr oc. IEEE

Military Communications Conf ., pp.17 (2008).





Documents

OPTICALCOMMUNICATIONPPT BHUVANA