Method and system for constructing no-hit-zone bipolar frequency hopping code

Abstract

The invention provides a method and system for constructing a no-hit-zone bipolar frequency hopping code. The method for constructing the no-hit-zone bipolar frequency hopping code includes the steps that first, a no-hit-zone frequency hopping sequence NHZ is constructed; second, a Walsh sequence is constructed; third, the no-hit-zone frequency hopping sequence NHZ and the Walsh sequence are combined to form the no-hit-zone bipolar frequency hopping code. The method and system for constructing the no-hit-zone bipolar frequency hopping code have the advantages that according to the constructed no-hit-zone bipolar frequency hopping code, all codons are totally orthogonal as long as the delay between users is within a zero correlation zone, so that multi-site interference and beat noise of a two-dimensional coherent OCDMA system will be completely eliminated, and the near-far effect of the two-dimensional coherent OCDMA system can also be eliminated. Therefore, by means of the no-hit-zone bipolar frequency hopping code constructed through the method and system, a high-capacity two-dimensional coherent OCDMA system can be achieved, and the no-hit-zone bipolar frequency hopping code can be applied to an optical access network, an optical local area network, an optical code label switching network, an optical fiber sensor network and the like.

Description

technical field [0001] The invention relates to the fields of optical access network, optical local area network, optical code label switching network, optical fiber sensor network, etc., and in particular relates to a construction method and system of a bipolar frequency hopping code with no collision area. 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. Based...

AI Technical Summary

Problems solved by technology

[0006] At present, the two-dimensional coherent OCDMA system uses a bipolar m-frequency hopping sequence, and the address codes 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

Images