Abstract

We consider short-range (1–3-km) free-space optical communication between moving parties when covertness is the overriding system performance requirement. To maximize covertness, it is critical to minimize the time required for the acquisition phase, during which the party initiating contact must conduct a broad-field scan and so risks revealing his position. Assuming an elliptical Gaussian beam profile, we show how to optimize the beam divergence angles, scan speed, and design of the raster scan pattern so as to minimize acquisition time. In this optimization, several constraints are considered, including: signal-to-noise ratio, required for accurate bearing detection and reliable decoding; limited receiver bandwidth; limited scanner speed; and beam divergence as limited by the scanner mirror dimensions. The effects of atmospheric turbulence are also discussed.

© 2002 Optical Society of America

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References

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  1. I. M. Teplyakov, “Acquisition and tracking of laser beams in space communications,” Acta Astron. 7, 341–355 (1980).
    [CrossRef]
  2. R. M. Gagliardi, S. Karp, Optical Communications (Wiley, New York, 1976).
  3. J. M. Lopez, K. Yong, “Acquisition, tracking, and fine pointing control of space-based laser communication system,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 100–114 (1981).
  4. S. G. Lambert, W. L. Casey, Laser Communications in Space (Artech House, Boston, Mass., 1995).
  5. E. S. Clarke, H. D. Brixey, “Acquisition and tracking system for a ground-based laser communication receiver terminal,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 162–169 (1981).
  6. R. B. Deadrick, “Design and performance of a satellite laser communications pointing system,” Adv. Astronaut. Sci. 57, 155–166 (1985).
  7. M. Scheinfeild, N. S. Kopeika, R. Melamed, “Acquisition system for microsatellites laser communication in space,” in Free-Space Laser Communication Technologies XII, G. S. Mecherle, ed., Proc. SPIE3932, 166–175 (2000).
  8. A. Yariv, Introduction to Optical Electronics, 2nd ed. (Holt, Rinehart and Winston, New York, 1976).
  9. J. D. Barry, G. S. Mecherle, “Beam pointing error as a significant design parameter for satellite-borne free-space optical communication systems,” Opt. Eng. 24, 1049–1054 (1985).
    [CrossRef]
  10. J. G. Proakis, Digital Communications, 3rd ed. (McGraw-Hill, New York, 1995).
  11. P. Djahani, J. M. Kahn, “Analysis of infrared wireless links employing multi-beam transmitters and imaging diversity receivers,” IEEE Trans. Commun. 48, 2077–2088 (2000).
    [CrossRef]
  12. A. L. Bloom, Gas Lasers (Wiley, New York, 1968).
  13. B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1991).
  14. L. C. Andrews, R. L. Phillips, Laser Beam Propagation through Random Media (SPIE Optical Engineering Press, Bellingham, Wash., 1998).
  15. C. C. Davis, I. I. Smolyaninov, “Effect of atmospheric turbulence on bit-error rate in an on-off-keyed optical wireless system,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 126–137 (2002).
  16. X. Zhu, J. M. Kahn, “Free-space optical communication through atmospheric turbulence channels,” IEEE Trans. Commun. 50, 1293–1300 (2002).
    [CrossRef]
  17. L. C. Andrews, R. L. Phillips, “Impact of scintillation on laser communication systems: recent advances in modeling,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 23–34 (2002).

2002

X. Zhu, J. M. Kahn, “Free-space optical communication through atmospheric turbulence channels,” IEEE Trans. Commun. 50, 1293–1300 (2002).
[CrossRef]

2000

P. Djahani, J. M. Kahn, “Analysis of infrared wireless links employing multi-beam transmitters and imaging diversity receivers,” IEEE Trans. Commun. 48, 2077–2088 (2000).
[CrossRef]

1985

R. B. Deadrick, “Design and performance of a satellite laser communications pointing system,” Adv. Astronaut. Sci. 57, 155–166 (1985).

J. D. Barry, G. S. Mecherle, “Beam pointing error as a significant design parameter for satellite-borne free-space optical communication systems,” Opt. Eng. 24, 1049–1054 (1985).
[CrossRef]

1980

I. M. Teplyakov, “Acquisition and tracking of laser beams in space communications,” Acta Astron. 7, 341–355 (1980).
[CrossRef]

Andrews, L. C.

L. C. Andrews, R. L. Phillips, Laser Beam Propagation through Random Media (SPIE Optical Engineering Press, Bellingham, Wash., 1998).

L. C. Andrews, R. L. Phillips, “Impact of scintillation on laser communication systems: recent advances in modeling,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 23–34 (2002).

Barry, J. D.

J. D. Barry, G. S. Mecherle, “Beam pointing error as a significant design parameter for satellite-borne free-space optical communication systems,” Opt. Eng. 24, 1049–1054 (1985).
[CrossRef]

Bloom, A. L.

A. L. Bloom, Gas Lasers (Wiley, New York, 1968).

Brixey, H. D.

E. S. Clarke, H. D. Brixey, “Acquisition and tracking system for a ground-based laser communication receiver terminal,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 162–169 (1981).

Casey, W. L.

S. G. Lambert, W. L. Casey, Laser Communications in Space (Artech House, Boston, Mass., 1995).

Clarke, E. S.

E. S. Clarke, H. D. Brixey, “Acquisition and tracking system for a ground-based laser communication receiver terminal,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 162–169 (1981).

Davis, C. C.

C. C. Davis, I. I. Smolyaninov, “Effect of atmospheric turbulence on bit-error rate in an on-off-keyed optical wireless system,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 126–137 (2002).

Deadrick, R. B.

R. B. Deadrick, “Design and performance of a satellite laser communications pointing system,” Adv. Astronaut. Sci. 57, 155–166 (1985).

Djahani, P.

P. Djahani, J. M. Kahn, “Analysis of infrared wireless links employing multi-beam transmitters and imaging diversity receivers,” IEEE Trans. Commun. 48, 2077–2088 (2000).
[CrossRef]

Gagliardi, R. M.

R. M. Gagliardi, S. Karp, Optical Communications (Wiley, New York, 1976).

Kahn, J. M.

X. Zhu, J. M. Kahn, “Free-space optical communication through atmospheric turbulence channels,” IEEE Trans. Commun. 50, 1293–1300 (2002).
[CrossRef]

P. Djahani, J. M. Kahn, “Analysis of infrared wireless links employing multi-beam transmitters and imaging diversity receivers,” IEEE Trans. Commun. 48, 2077–2088 (2000).
[CrossRef]

Karp, S.

R. M. Gagliardi, S. Karp, Optical Communications (Wiley, New York, 1976).

Kopeika, N. S.

M. Scheinfeild, N. S. Kopeika, R. Melamed, “Acquisition system for microsatellites laser communication in space,” in Free-Space Laser Communication Technologies XII, G. S. Mecherle, ed., Proc. SPIE3932, 166–175 (2000).

Lambert, S. G.

S. G. Lambert, W. L. Casey, Laser Communications in Space (Artech House, Boston, Mass., 1995).

Lopez, J. M.

J. M. Lopez, K. Yong, “Acquisition, tracking, and fine pointing control of space-based laser communication system,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 100–114 (1981).

Mecherle, G. S.

J. D. Barry, G. S. Mecherle, “Beam pointing error as a significant design parameter for satellite-borne free-space optical communication systems,” Opt. Eng. 24, 1049–1054 (1985).
[CrossRef]

Melamed, R.

M. Scheinfeild, N. S. Kopeika, R. Melamed, “Acquisition system for microsatellites laser communication in space,” in Free-Space Laser Communication Technologies XII, G. S. Mecherle, ed., Proc. SPIE3932, 166–175 (2000).

Phillips, R. L.

L. C. Andrews, R. L. Phillips, “Impact of scintillation on laser communication systems: recent advances in modeling,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 23–34 (2002).

L. C. Andrews, R. L. Phillips, Laser Beam Propagation through Random Media (SPIE Optical Engineering Press, Bellingham, Wash., 1998).

Proakis, J. G.

J. G. Proakis, Digital Communications, 3rd ed. (McGraw-Hill, New York, 1995).

Saleh, B. E. A.

B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1991).

Scheinfeild, M.

M. Scheinfeild, N. S. Kopeika, R. Melamed, “Acquisition system for microsatellites laser communication in space,” in Free-Space Laser Communication Technologies XII, G. S. Mecherle, ed., Proc. SPIE3932, 166–175 (2000).

Smolyaninov, I. I.

C. C. Davis, I. I. Smolyaninov, “Effect of atmospheric turbulence on bit-error rate in an on-off-keyed optical wireless system,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 126–137 (2002).

Teich, M. C.

B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1991).

Teplyakov, I. M.

I. M. Teplyakov, “Acquisition and tracking of laser beams in space communications,” Acta Astron. 7, 341–355 (1980).
[CrossRef]

Yariv, A.

A. Yariv, Introduction to Optical Electronics, 2nd ed. (Holt, Rinehart and Winston, New York, 1976).

Yong, K.

J. M. Lopez, K. Yong, “Acquisition, tracking, and fine pointing control of space-based laser communication system,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 100–114 (1981).

Zhu, X.

X. Zhu, J. M. Kahn, “Free-space optical communication through atmospheric turbulence channels,” IEEE Trans. Commun. 50, 1293–1300 (2002).
[CrossRef]

Acta Astron.

I. M. Teplyakov, “Acquisition and tracking of laser beams in space communications,” Acta Astron. 7, 341–355 (1980).
[CrossRef]

Adv. Astronaut. Sci.

R. B. Deadrick, “Design and performance of a satellite laser communications pointing system,” Adv. Astronaut. Sci. 57, 155–166 (1985).

IEEE Trans. Commun.

P. Djahani, J. M. Kahn, “Analysis of infrared wireless links employing multi-beam transmitters and imaging diversity receivers,” IEEE Trans. Commun. 48, 2077–2088 (2000).
[CrossRef]

X. Zhu, J. M. Kahn, “Free-space optical communication through atmospheric turbulence channels,” IEEE Trans. Commun. 50, 1293–1300 (2002).
[CrossRef]

Opt. Eng.

J. D. Barry, G. S. Mecherle, “Beam pointing error as a significant design parameter for satellite-borne free-space optical communication systems,” Opt. Eng. 24, 1049–1054 (1985).
[CrossRef]

Other

J. G. Proakis, Digital Communications, 3rd ed. (McGraw-Hill, New York, 1995).

M. Scheinfeild, N. S. Kopeika, R. Melamed, “Acquisition system for microsatellites laser communication in space,” in Free-Space Laser Communication Technologies XII, G. S. Mecherle, ed., Proc. SPIE3932, 166–175 (2000).

A. Yariv, Introduction to Optical Electronics, 2nd ed. (Holt, Rinehart and Winston, New York, 1976).

R. M. Gagliardi, S. Karp, Optical Communications (Wiley, New York, 1976).

J. M. Lopez, K. Yong, “Acquisition, tracking, and fine pointing control of space-based laser communication system,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 100–114 (1981).

S. G. Lambert, W. L. Casey, Laser Communications in Space (Artech House, Boston, Mass., 1995).

E. S. Clarke, H. D. Brixey, “Acquisition and tracking system for a ground-based laser communication receiver terminal,” in Control and Communication Technology in Laser Systems, K. Yong, ed., Proc. SPIE295, 162–169 (1981).

L. C. Andrews, R. L. Phillips, “Impact of scintillation on laser communication systems: recent advances in modeling,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 23–34 (2002).

A. L. Bloom, Gas Lasers (Wiley, New York, 1968).

B. E. A. Saleh, M. C. Teich, Fundamentals of Photonics (Wiley, New York, 1991).

L. C. Andrews, R. L. Phillips, Laser Beam Propagation through Random Media (SPIE Optical Engineering Press, Bellingham, Wash., 1998).

C. C. Davis, I. I. Smolyaninov, “Effect of atmospheric turbulence on bit-error rate in an on-off-keyed optical wireless system,” in Free-Space Laser Communication and Laser Imaging, D. G. Voelz, J. C. Ricklin, eds., Proc. SPIE4489, 126–137 (2002).

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Figures (4)

Fig. 1
Fig. 1

Example of a short-range free-space optical communication system configuration.

Fig. 2
Fig. 2

Link initiation–acquisition protocol. IV code, identity-verifying code.

Fig. 3
Fig. 3

Scan patterns for the standard raster scan and the double-looped raster scan. The rectangular search field is divided into many columns. Each column contains n vertical paths. In each column the initiator first performs a standard raster scan, transmitting the all-1 code. At the end of this scan, the beam is then moved back n paths, and a double-looped scan is performed, sending the all-1 code and an IV code on alternate loops.

Fig. 4
Fig. 4

Scanning geometry during the acquisition process. The rectangle inside the beam is referred as the effective beam spot.

Tables (2)

Tables Icon

Table 1 Double-Looped Raster Scan: Optimal Beam Divergences, Bit Interval, and Minimized Full-Field Scan Timea

Tables Icon

Table 2 Standard Raster Scan: Beam Divergences, Optimal Value of Round-Trip Scan Time, and Minimized Full-Field Scan Time

Equations (31)

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Tacq=mτs+τd=mτs+mτd.
Tacq=Ts+Td.
PΦx, Φy, βx, βy=2IΦx, Φy, βx, βyLoARPt cos Ψ/πd2,
IΦx, Φy, βx, βy=exp-2βx2/Φx2+βy2/Φy2/ΦxΦy.
Φx=2βx, Φy=2βy.
PMD=ProbUi<h|pixel i illuminatedJ=Qμ1-hσ1J,
PFA=1-ProbUi<h|pixel i not illuminatedM=1-1-Qhσ1M.
PsΦx, Φy, βx, θy=2LoARPt cos Ψπd2ΦxΦyexp-12×exp-2θy2Φy2,
SNR=-RPsJωdθy2N0Tint,
SNR=κT12/Φx2,
Ts=αT1/2Φx.
Ts=α/2SNR/κ.
Pb=QSNR/2.
PMD=1-1-PbN.
PFA=12N-1i=1NNiPbi1-PbN-i=PMD2N-1.
Pd=2LoARPt cos Ψ/πed2ΦxΦy,
SNR=R2Pd2T/JN0=χT/Φx2Φy2,
Td=αT2/Φx.
ΦxΦxminλ/πr, ΦyΦyminλ/πr,
Tsmin=α/2SNR1/κ.
ΦxSNR1/κTy.
TΦx2Φy2SNR2/χ.
TΦyTy/2Nα.
T1/Brec.
Td2Nα2 maxAΦxΦy, BΦx, CΦxΦy,
Tdmin=2Nα2AC.
ΦyΦymax.
Tdmin=2Nα2ABΦymin.
pi=12πσliexp-12σl2ln i+12σl22,
Pb=120Qi-ithSNRpidi+QithSNR,
PMD=0QiSNR-h/σ1pidiJ,

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