Abstract

The free-space optical (FSO) communications can provide any connectivity need at high-speed. However, an optical wave propagating through the atmosphere experiences the variation in amplitude and phase due to scintillation. To enable high-speed communication over strong atmospheric turbulence channels, we propose to transmit the encoded sequence over both FSO and wireless channels, feedback channel state information of both channels by RF-feedback, and adapt powers and rates so that total channel capacity is maximized. The optimum power adaptation policy maximizing total channel capacity is derived. We show significant spectral efficiency performance improvement by employing this approach. We further show that deep fades in the order 35 dB and above can be tolerated by proposed hybrid communication scheme.

© 2009 OSA

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References

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  1. L. C. Andrews, and R. L. Philips, Laser Beam Propagation through Random Media (SPIE Press, 2005).
  2. I. B. Djordjevic, B. Vasic, and M. A. Neifeld, “LDPC coded OFDM over the atmospheric turbulence channel,” Opt. Express 15, 6332–6346 (2007).
    [CrossRef]
  3. I. B. Djordjevic, S. Denic, J. Anguita, B. Vasic, and M. A. Neifeld, “LDPC-coded MIMO optical communication over the atmospheric turbulence channel,” J. Lightwave Technol. 26(5), 478–487 (2008).
    [CrossRef]
  4. J. A. Anguita, M. A. Neifeld, B. Hildner, and B. Vasic, “Raptor codes for the temporally correlated FSO channel,” submitted for publication.
  5. S. Denic, I. B. Djordjevic, J. Anguita, B. Vasic, and M. A. Neifeld, “Information theoretic limits for free-space optical channels with and without memory,” J. Lightwave Technol. 26(19), 3376–3384 (2008).
    [CrossRef]
  6. A. Goldsmith, Wireless Communications (Cambridge University Press, Cambridge 2005).
  7. A. Goldsmith and S.-G. Chua, “Adaptive coded modulation for fading channels,” IEEE Trans. Commun. 46(5), 595–602 (1998).
    [CrossRef]
  8. M. D. Yacoub, “The α-μ distribution: a general fading distribution,” in Proc. IEEE Int. Symp. PIMRC, vol. 2, pp. 629–633, 2002.
  9. M. D. Yacoub, “The α-μ distribution: a physical fading model for the Stacy distribution,” IEEE Trans. Vehicular Technol. 56(1), 27–34 (2007).
    [CrossRef]
  10. M. A. Al-Habash, L. C. Andrews, and R. L. Phillips, “Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media,” Opt. Eng. 40(8), 1554–1562 (2001).
    [CrossRef]
  11. J. A. Anguita, I. B. Djordjevic, M. A. Neifeld, and B. V. Vasic, “Shannon capacities and error–correction codes for optical atmospheric turbulent channels,” J. Opt. Netw. 4(9), 586–601 (2005).
    [CrossRef]
  12. M. P. C. Fossorier, “Quasi-cyclic low-density parity-check codes from circulant permutation matrices,” IEEE Trans. Inf. Theory 50(8), 1788–1793 (2004).
    [CrossRef]
  13. H. Xiao-Yu, E. Eleftheriou, D.-M. Arnold, and A. Dholakia, “Efficient implementations of the sum-product algorithm for decoding of LDPC codes,” In Proc. IEEE Globecom 2001, vol. 2, pp. 1036–1036E, 2001.
  14. T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
    [CrossRef]
  15. A. A. Farid, and S. Hranilovic, “Upper and lower bounds on the capacity of wireless optical intensity channels,” in Proc. ISIT 2007, pp. 2416–2420, Nice, France, June 24-June 29, 2007.

2008 (2)

2007 (2)

M. D. Yacoub, “The α-μ distribution: a physical fading model for the Stacy distribution,” IEEE Trans. Vehicular Technol. 56(1), 27–34 (2007).
[CrossRef]

I. B. Djordjevic, B. Vasic, and M. A. Neifeld, “LDPC coded OFDM over the atmospheric turbulence channel,” Opt. Express 15, 6332–6346 (2007).
[CrossRef]

2005 (1)

2004 (2)

M. P. C. Fossorier, “Quasi-cyclic low-density parity-check codes from circulant permutation matrices,” IEEE Trans. Inf. Theory 50(8), 1788–1793 (2004).
[CrossRef]

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

2001 (1)

M. A. Al-Habash, L. C. Andrews, and R. L. Phillips, “Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media,” Opt. Eng. 40(8), 1554–1562 (2001).
[CrossRef]

1998 (1)

A. Goldsmith and S.-G. Chua, “Adaptive coded modulation for fading channels,” IEEE Trans. Commun. 46(5), 595–602 (1998).
[CrossRef]

Akita, M.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Al-Habash, M. A.

M. A. Al-Habash, L. C. Andrews, and R. L. Phillips, “Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media,” Opt. Eng. 40(8), 1554–1562 (2001).
[CrossRef]

Andrews, L. C.

M. A. Al-Habash, L. C. Andrews, and R. L. Phillips, “Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media,” Opt. Eng. 40(8), 1554–1562 (2001).
[CrossRef]

Anguita, J.

Anguita, J. A.

Chua, S.-G.

A. Goldsmith and S.-G. Chua, “Adaptive coded modulation for fading channels,” IEEE Trans. Commun. 46(5), 595–602 (1998).
[CrossRef]

Denic, S.

Djordjevic, I. B.

Fossorier, M. P. C.

M. P. C. Fossorier, “Quasi-cyclic low-density parity-check codes from circulant permutation matrices,” IEEE Trans. Inf. Theory 50(8), 1788–1793 (2004).
[CrossRef]

Fujita, H.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Goldsmith, A.

A. Goldsmith and S.-G. Chua, “Adaptive coded modulation for fading channels,” IEEE Trans. Commun. 46(5), 595–602 (1998).
[CrossRef]

Kobayashi, T.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Kubo, K.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Kuno, K.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Miyata, Y.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Mizuochi, T.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Motoshima, K.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Neifeld, M. A.

Ouchi, K.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Phillips, R. L.

M. A. Al-Habash, L. C. Andrews, and R. L. Phillips, “Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media,” Opt. Eng. 40(8), 1554–1562 (2001).
[CrossRef]

Shimizu, K.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Tagami, H.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

Vasic, B.

Vasic, B. V.

Yacoub, M. D.

M. D. Yacoub, “The α-μ distribution: a physical fading model for the Stacy distribution,” IEEE Trans. Vehicular Technol. 56(1), 27–34 (2007).
[CrossRef]

Yoshida, H.

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron. (1)

T. Mizuochi, Y. Miyata, T. Kobayashi, K. Ouchi, K. Kuno, K. Kubo, K. Shimizu, H. Tagami, H. Yoshida, H. Fujita, M. Akita, and K. Motoshima, “Forward error correction based on block turbo code with 3-bit soft decision for 10-Gb/s optical communication systems,” IEEE J. Sel. Top. Quantum Electron. 10(2), 376–386 (2004).
[CrossRef]

IEEE Trans. Commun. (1)

A. Goldsmith and S.-G. Chua, “Adaptive coded modulation for fading channels,” IEEE Trans. Commun. 46(5), 595–602 (1998).
[CrossRef]

IEEE Trans. Inf. Theory (1)

M. P. C. Fossorier, “Quasi-cyclic low-density parity-check codes from circulant permutation matrices,” IEEE Trans. Inf. Theory 50(8), 1788–1793 (2004).
[CrossRef]

IEEE Trans. Vehicular Technol. (1)

M. D. Yacoub, “The α-μ distribution: a physical fading model for the Stacy distribution,” IEEE Trans. Vehicular Technol. 56(1), 27–34 (2007).
[CrossRef]

J. Lightwave Technol. (2)

J. Opt. Netw. (1)

Opt. Eng. (1)

M. A. Al-Habash, L. C. Andrews, and R. L. Phillips, “Mathematical model for the irradiance probability density function of a laser beam propagating through turbulent media,” Opt. Eng. 40(8), 1554–1562 (2001).
[CrossRef]

Opt. Express (1)

I. B. Djordjevic, B. Vasic, and M. A. Neifeld, “LDPC coded OFDM over the atmospheric turbulence channel,” Opt. Express 15, 6332–6346 (2007).
[CrossRef]

Other (6)

L. C. Andrews, and R. L. Philips, Laser Beam Propagation through Random Media (SPIE Press, 2005).

J. A. Anguita, M. A. Neifeld, B. Hildner, and B. Vasic, “Raptor codes for the temporally correlated FSO channel,” submitted for publication.

A. Goldsmith, Wireless Communications (Cambridge University Press, Cambridge 2005).

M. D. Yacoub, “The α-μ distribution: a general fading distribution,” in Proc. IEEE Int. Symp. PIMRC, vol. 2, pp. 629–633, 2002.

H. Xiao-Yu, E. Eleftheriou, D.-M. Arnold, and A. Dholakia, “Efficient implementations of the sum-product algorithm for decoding of LDPC codes,” In Proc. IEEE Globecom 2001, vol. 2, pp. 1036–1036E, 2001.

A. A. Farid, and S. Hranilovic, “Upper and lower bounds on the capacity of wireless optical intensity channels,” in Proc. ISIT 2007, pp. 2416–2420, Nice, France, June 24-June 29, 2007.

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Figures (7)

Fig. 1
Fig. 1

System model. S/P: serial-to-parallel conversion, LD: laser diode, ADC: A/D converter, P/S parallel-to-serial converter, APP: a posteriori probability.

Fig. 2
Fig. 2

Non-adaptive uncoded and LDPC(16935,13550)-coded MQAM and MAPM BERs for: (a) FSO channel, and (b) α-μ wireless fading channel.

Fig. 3
Fig. 3

Spectral efficiencies of FSO system against symbol SNR for different target bit probabilities of error: (a) in weak turbulence regime, and (b) in strong turbulence regime.

Fig. 4
Fig. 4

Spectral efficiencies of hybrid FSO-RF system with α = 3, μ = 2 fading against symbol SNR for different target bit probabilities of error: (a) in weak turbulence regime, and (b) in strong turbulence regime.

Fig. 5
Fig. 5

Spectral efficiencies of hybrid FSO-RF system with α = 2, μ = 1 (Rayleigh) fading against symbol SNR for different target bit probabilities of error: (a) in weak turbulence regime, and (b) in strong turbulence regime.

Fig. 6
Fig. 6

BER performance of adaptive LDPC code for QPSK with Gray mapping.

Fig. 7
Fig. 7

Spectral efficiencies against symbol SNR for adaptive LDPC-coded modulation: (a) FSO with RF feedback only, and (b) hybrid FSO-RF system.

Equations (21)

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sk=rkejγkck+wk,
p(rk)=αμμrkαμ1r^αμΓ(μ)exp(μrkαr^α),
μ=E2{rkα}/Var{rkα},
r^=E{rkα}α.
zk=rkck+wk.
yk=Rikxk+nk,
p(ik)=2(α'β')(α'+β')/2Γ(α')Γ(β')ik(α'+β')/21Kα'β'(2α'β'ik), ik>0
α'=1exp[0.49σR2(1+1.11σR12/5)7/6]1,                         β'=1exp[0.51σR2(1+0.69σR12/5)5/6]1
σR2=1.23Cn2k7/6L11/6,
H=[III...IIPS[1]PS[2]...PS[wr1]IP2S[1]P2S[2]...P2S[wr1]...............IP(wc1)S[1]P(wc1)S[2]...P(wc1)S[wr1]],
PbMPAMM1Mlog2Merfc(3Γ0MPAM2(M1)(2M1)),
PbMPAM0.2exp[1.85Γ0MPAM22.19log2M1].
R=12.19BFSOlog2(1+KFSOΓ0FSO)+BRFlog2(1+KRFΓ0RF),
R=12.19BFSOlog2(1+KFSOΓFSO(ik)PFSO(ik)P)+BRFlog2(1+KRFΓRF(h)PRF(h)P),
KFSOPFSO(ik)P={1Γtsh1ΓFSO,   ΓFSOΓtsh0,     ΓFSO<Γtsh,             ΓFSO=Γ0FSOik2KRFPRF(h)P={1Γtsh1ΓRF,   ΓRFΓtsh0,     ΓRF<Γtsh,             ΓRF=Γ0RFh2         
Γtsh/Γ0FSO(1KFSOΓtsh1KFSOΓ0FSOik2)p(ik)dik+bΓtsh/Γ0RF(1KRFΓtsh1KRFΓ0RFh2)p(h)dh=1
RB=12.19Γtsh/Γ0FSOlog2(Γ0FSOik2Γtsh)p(ik)dik+bΓtsh/Γ0RFlog2(Γ0RFh2Γtsh)p(h)dh   [bits/s/Hz]
PFSO(ik)P={1ik2EΓtshFSO[1/ik2],     ΓFSOΓtsh0,                                       ΓFSO<itsh                 PRF(h)P={1h2EΓtshRF[1/h2],     ΓRFΓtsh0,                                                   ΓRF<Γtsh
EΓtshFSO[1ik2]=Γtsh/Γ0FSOp(ik)ik2dik,   EΓtshRF[1h2]=Γtsh/Γ0RFp(h)h2dh
R=maxΓtsh{12.19BFSOlog2(1+KFSOΓ0FSO1EΓtshFSO[1/ik2])P(ikΓtsh/Γ0FSO)                                           +BRFlog2(1+KRFΓ0RF1EΓtshRF[1/h2])P(hΓtsh/Γ0RF)}
P(ikΓtsh/Γ0FSO)=Γtsh/Γ0FSOp(ik)dik                 P(hΓtsh/Γ0RF)=Γtsh/Γ0RFp(h)dh

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