A novel repetition space-time coding scheme for mobile FSO systems

Abstract

Considering the influence of more random atmospheric turbulence, worse pointing errors and highly dynamic link on the transmission performance of mobile multiple-input multiple-output (MIMO) free space optics (FSO) communication systems, this paper establishes a channel model for the mobile platform. Based on the combination of Alamouti space-time code and time hopping ultra-wide band (TH-UWB) communications, a novel repetition space-time coding (RSTC) method for mobile 2×2 free-space optical communications with pulse position modulation (PPM) is developed. In particular, two decoding methods of equal gain combining (EGC) maximum likelihood detection (MLD) and correlation matrix detection (CMD) are derived. When a quasi-static fading and weak turbulence channel model are considered, simulation results show that whether the channel state information (CSI) is known or not, the coding system demonstrates more significant performance of the symbol error rate (SER) than the uncoding. In other words, transmitting diversity can be achieved while conveying the information only through the time delays of the modulated signals transmitted from different antennas. CMD has almost the same effect of signal combining with maximal ratio combining (MRC). However, when the channel correlation increases, SER performance of the coding 2×2 system degrades significantly.

Keywords

Channel State Information / Channel Gain / Maximal Ratio Combine / Symbol Error Rate / Free Space Optic

References

[1] LiM, HuangY, CaoY, YangS-w. Journal of Optoelectronics·Laser, 2014, 25: 1310

[2] LiM, LiS-m, YangS-w. Journal of Optoelectronics·Laser, 2013, 24: 710

[3] LiM, CaoY, LiS. Chinese Journal of Lasers, 2013, 40: 0405004

[4] LiM, HuangY, AiY. Infrared and Laser Engineering, 2010, 39: 270

[5] LiM, HuangY, AiY. China Communications, 2010, 7: 138

[6] HaasS M. Space-time Codes for Wireless Optical Channels, 2001, Washington, DC, IEEE Transactions on Information Theory, 244

[7] KeX, SongP, PeiG. Acta Optica Sinica, 2011, 31: 1

[8] ZhaoL, KeX, WangH. Chinese Journal of Lasers, 2009, 36: 2757

[9] WangH, KeX. Chinese Journal of Lasers, 2008, 35: 874

[10] WangH, KeX. Acta Optica Sinica, 2008, 29: 132

[11] WangH, KeX, ZhaoL. Science in China Series F, 2009, 52: 1483

[12] BayakiE, SchoberR. Journal of Lightwave Technology, 2011, 30: 1569

[13] Abou-RjeilyC. IEEE Journal on Selected Areas in Communications, 2008, 26: 938

[14] Abou-RjeilyC. IEEE Transactions on Wireless Communications, 2011, 10: 2402

[15] BayakiE, SchoberR. IEEE Transactions on Communications, 2010, 58