A novel timing synchronization for CO-OFDM systems using CAZAC sequences

Abstract

A novel symbol timing synchronization algorithm based on constant amplitude zero auto correlation (CAZAC) sequences is proposed for coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. The training symbol of the proposed algorithm is comprised of four different parts, utilizing even symmetry property of each part to accomplish timing synchronization. The performance of the proposed algorithm is demonstrated by means of simulations in OFDM and CO-OFDM systems. The proposed algorithm is shown to eliminate the timing sidelobes of Park’s algorithm and has a more accurate timing estimation. In the condition of chromatic dispersion (CD), the timing metric of the proposed method still maintains its peak value at the correct timing point, while the values are almost 0 at all the other positions. Meanwhile, the timing mean square error (MSE) of the proposed algorithm remains around 10^-6.

References

[1] CHENGZ-H, BAIC-l, LUOQ-L, SUNW-T. Journal of Optoelectronics·Laser, 2015, 26: 1097

[2] ShuaiZ, Shun-changB, Cheng-linB, Qing-longL. Optoelectronics Letters, 2014, 10: 140

[3] ZhaoB. Li Li, Han Li and Hu Gui-jun, Journal of Optoelectronics·Laser, 2016, 27: 1005

[4] LeS T, McCarthyM E, GiacoumidisE, DoranN JAdaptive Time Synchronization and Frequency Offset Estimation for CO-OFDM9th International Symposium on Communication Systems, 2014,

[5] Bai Cheng-lin and Cheng Zhi-hui, Optoelectronics Letters 12, 353 (2016).

[6] DuX, ZhangJ, XuZ. Opt. Express, 2016, 24: 19969

[7] WangL, XianfengT, XiaoguangZ, ZhangX, LixiaX. Modified Timing Synchronization Methods for CO-OFDM System Stressed by CD and PMD, Asia Communications and Photonics Conference, 2013,

[8] SchmidlT M, CoxD C. IEEE Trans. Commun., 1997, 45: 1613

[9] MinnH, ZengM, BhargavaV. Communications Letters, 2000, 4: 242

[10] ParkB, CheonH, KangC. Communications Letters, 2003, 7: 239

[11] ShaoH, LiY, TanJ, XuY, LiuGRobust Timing and Frequency Synchronization Based on Constant Amplitude Zero Autocorrelation Sequence for OFDM SystemsIEEE International Conference on Communication Problem-solving, 2014, 14

[12] WangH, ZhuL, ShiY, WangY. Comput. Inf. Syst., 2012, 8: 2275

[13] SilvaC E M, HarrisF J, DolecekG JSynchronization Algorithms Based on Weighted CAZAC Preambles for OFDM Systems13th International Symposium on Communications and Information Technologies, 2013, 192

[14] JiantaoJ. Science and Technology, 2015, 33: 66

[15] OluyemiO, DeyuanC, JingwenZ, OctaviaD, RamachandranV. Optics Express, 2015, 23: 5377

[16] LiL, WuD. Journal of Optoelectronics·Laser, 2015, 26: 1692