Experimental validation of an undersea free space laser network

physical layer simulator

David Rashkin*, Fraser Dalgleish**, Ionut Cardei*, Bing Ouyang**, Anni Vuorenkoski**,

Mihaela Cardei*

*Florida Atlantic University, Department of Computer and Electrical Engineering and Computer Science, Boca Raton, Florida

**Ocean Visibility and Optics Lab, Harbor Branch Oceanographic Institute, Fort Pierce, Florida

Agenda

Introduction Physical Layer Simulator Experimental Setup Results Discussion / Future Work Questions

Introduction

Complete network simulator requires accurate physical layer model

Gbps communication requires laser sources capable of sub-nanosecond pulses

With these timing requirements, it is necessary to understand how the channel affects the pulses

Use 95% CL BER as

performance metric

Physical Layer Simulator

Modulator Channel Model PMT Detector Model Demodulator

Modulator Inputs:

Sampling interval (1 ns) Source laser peak power (160 mW) Source laser variance (~ 3-5%) Modulation scheme (PPM-16) Pulse repetition rate (100Mhz, 200Mhz, 250Mhz,

500Mhz) Bitstream (pseudorandom)

Outputs: 1 dimensional array representing clean signal

Channel Model Inputs:

Beam attenuation coefficient (c)

Absorption coefficient (a)

Scattering phase function

Position and orientation of source and receivers in 3D space

Beam divergence

Receiver half-angle, radius and acceptance shape

Outputs:

Two impulse response matrices, one for a receiver in forward direction and another for a receiver collecting the backscattered signal

Channel Model

Channel Model

PMT Detector Model

Inputs: 1 dimensional array representing simulated signal

in terms of optical power Source laser wavelength Detector quantum efficiency Detector gain

Outputs: 1 dimensional array representing noisy signal in

terms of voltage

PMT Detector Model

Shot noise limited Continuous Poisson random variable Per-sample noise drawn from multivariate

Gaussian distribution

Demodulator

Inputs: 1 dimensional array representing noisy signal Pulse repetition rate (frequency) Sampling interval Modulation scheme

Outputs: Demodulated bitstream

Experimental Setup

North Lab

WestLab

East Lab

Movable Catwalk (Z)

Linear Drive (X,Y)3 Axis Deployment Carriage

12.5 x 7.5 x 2.5 m

Turbidity controlled using ISO 12103-1 A1 Ultrafine Arizonta Test Dust

Beam attenuation and absorption coefficients measured using Wet Labs AC9

Experimental Setup

Omicron A350 405nm pulsed laser,160mW peak power

Agilent 81130A pulse generator Hamamatsu R9880U-210 PMT PXI 5154 high speed 8-bit digitizer (1 Gsps)

Results

Results

Discussion / Future Work

Off axis cases Full duplex / half duplex communication System design tool NLOS communication scenarios At-sea data

Acknowledgments

ONR Joe Shirron, Metron Inc. Tom Giddings, Metron Inc. Benjamin Metzer, HBOI Walter Britton, HBOI Brian Ramos, HBOI Drew Krupski, HBOI

Questions?

?

Previous Work

[1] Dalgleish, Fraser; Vuorenkoski, Anni; Ouyang, Bing; Caimi, Frank; Shirron, Joseph; Giddings,Thomas; Mazel, Charles, “Experimental and analytical channel impulse Response investigation for distributed laser serial imaging and non line of sight communications sensors in turbid coastal conditions”, In Proc. Ocean Optics XXI, Glasgow, UK. October 2012.

[2] Vuorenkoski, A. K., Dalgleish, F. R., Metzger, B., Giddings, T. E. and Shirron, J. J. "Multi-path effects on optical communications links," Proc. ONR/NASA Ocean Optics XX. Sept 27th-Oct 1st 2010. Anchorage, AK.

[3] Rashkin, D.; Cardei, I.; Cardei, M.; Dalgleish, F.; Giddings, T., "Detector noise model verification for undersea free space optical data links," Oceans, 2012 , vol., no., pp.1,7, 14-19 Oct. 2012

[4] Ouyang, B. Dalgleish, F. R. Vuorenkoski, A.K., Britton, W.B., Ramos B. and Metzger, B., "Visualization for Multi-static Underwater LLS System using Image Based Rendering", IEEE Journal of Oceanic Engineering. 2012. (accepted)