A method and system for constructing a two-dimensional bipolar code with zero correlation region in time/frequency domain

Abstract

The present invention provides a method and a system for constructing a two-dimensional bipolar code with a time / frequency domain zero-correlation zone. The construction method comprises: A. constructing a time domain zero-correlation zone spreading sequence LA having a zero-correlation zone; B. constructing a single-coincidence sequence in a frequency domain; C. constructing a Walsh sequence; D. combining the time domain zero-correlation zone spreading sequence having the zero-correlation zone with the single-coincidence sequence in the frequency domain to form a two-dimensional optical orthogonal code with a time / frequency domain zero-correlation zone; and E. combining the two-dimensional optical orthogonal code with the time / frequency domain zero-correlation zone with the Walsh sequence to form a two-dimensional bipolar code with a time / frequency domain zero-correlation zone. The present invention is beneficial in that the present invention completely eliminates multiple access interference and beat noise of a two-dimensional coherent OCDMA system, and can also eliminate the near-far effect of the two-dimensional coherent OCDMA system. Therefore, the present invention can realize a large-capacity two-dimensional coherent OCDMA system for application to an optical access network, an optical local area network, an optical code label switching network, a fiber optic sensor network, and the like.

Description

technical field [0001] The invention relates to the field of communication technology, in particular to a construction method and system for a time / frequency domain zero-correlation zone two-dimensional bipolar code. Background technique [0002] Optical Code Division Multiple Access (OCDMA) has the characteristics of broadband, security and random instant access, and is one of the best solutions for future high-speed local area networks and access networks. According to the degree of freedom, it can be divided into one-dimensional OCDMA system and two-dimensional OCDMA system. The address code of the two-dimensional OCDMA system not only expands in the time domain, but also expands in the wavelength, which is called two-dimensional optical orthogonal code. [0003] At present, many scholars at home and abroad have constructed many types of two-dimensional OCDMA address codes. PC / PC and EQC / PC were constructed based on Primecode (Primecode), Tancevski.L, etc. The autocorrel...

AI Technical Summary

Problems solved by technology

At present, the two-dimensional coherent OCDMA system uses a bipolar m-frequency hopping sequence, the address code cannot be completely orthogonal (the minimum cross-correlation limit is 1), and the cross-correlation characteristics are not ideal, so the system has multiple access interference and beat noise

Especially when the number of concurrent users is large, multiple access interference and beat noise become the most important noises, causing the bit error rate of the two-dimensional coherent OCDMA system to rise sharply, thereby limiting the number of access users of the two-dimensional coherent OCDMA

At the same time, since the address codes cannot be completely orthogonal, the near-far effect exists in the two-dimensional coherent OCDMA system, which requires complex power control

Therefore, the current two-dimensional coherent OCDMA system is difficult to be practical

[0006] Ji Jianhua and others constructed a bipolar frequency hopping code with no collision zone, which can eliminate multiple access interference and beat noise, but the code word capacity is small (equal to the effective number of wavelengths of the system), which limits the capacity of the two-dimensional coherent OCDMA system. Unable to realize large-capacity two-dimensional coherent OCDMA system

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