Time synchronization method of access system of optical orthogonal frequency division multiplexing-based passive optical network (OOFDM-PON)

Abstract

The invention discloses a time synchronization method in a system of an optical orthogonal frequency division multiplexing-based passive optical network (OOFDM-PON). The scheme comprises an optical line terminal (OLT) and an optical network unit (ONU), wherein the OLT comprises a laser, a modulator, an OFDM signal generating module and an optical multiplexer. The ONU comprises an optical demultiplexer, a time delay compensator, an optical detector and an OFDM receiving module. At the transmitting end of the OLT, optical signals for modulating optical OFDM signals and timing information are divided into two branches. The optical signals are divided into two branches after transmitted by optical fibers, wherein a timing signal is extracted from the branch for carrying the timing information by the optical detector after time-delay compensation, and the OFDM signals are accurately received at the receiving end of the ONU. The invention has the characteristics of simple design principle, easy realization, low cost and the like.

Description

technical field [0001] The invention belongs to the technical field of optical communication, and in particular relates to an optical orthogonal frequency division multiplexing-based passive optical network (OOFDM-PON) access and time synchronization technology. Background technique [0002] Synchronization technology is one of the key technologies of Orthogonal Frequency Division Multiplexing (OFDM) communication system, and it is also the key technology of Optical Orthogonal Frequency Division Multiplexing (OOFDM) and Optical Orthogonal Frequency Division Multiplexing-based Passive Optical Network (OOFDM-PON). The key to the practicality of the access system. OOFDM-PON access is divided into two systems: coherent and non-coherent. Among them, the performance of the coherent OOFDM-PON access system is better, but it is difficult to implement and the cost is high; the non-coherent OOFDM-PON access technology uses direct modulation intensity detection. The implementation is ...

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Problems solved by technology

Some documents directly cite some commonly used synchronization methods in wireless OFDM technology, such as M.Schmidl and D.Cox, "Robust frequency and timing synchronization for OFDM," IEEE Trans.Commun., vol.45, pp.1613 -1621, Dec.1997; H.Minn, M.Zeng and V.Bhargava, "On timing offset estimation for OFDM systems," IEEE Commun.Lett., vol.4, pp.242-244, July 2000; B. Park, H.Cheon, C.Kang, "A Novel Timing Estimation Method for OFDM Systems," IEEE Lett.Commun., 2003, 7(5): 239-241 and other algorithms, but the classic algorithms in these wireless channels are basically Pilot signals are required, on the one hand, the effectiveness of the system is reduced, and complex data processing is required at the receiving end, which will occupy a large amount of data processing resources in a high-speed transmission system, and the cost will be very high

In the high-speed OOFDM-PON system, it is obviously unreasonable to realize high-speed data processing at the receiving end, because it needs to occupy a lot of resources and the cost is also high

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