基于2D-OOC的OCDMA系统的地址码结构研究

提出了二维光正交码(2D-OOC)设计方案,围绕光码分多址(OCDMA)技术实用化的两个主要指标-最大并发用户数和系统误码率的改进和提高,系统地研究了基于2D-OOC的OCDMA的性能,分析了2D-OOC码字的相关性,导出了系统的最大用户容量,详细研究了2D-OOC系统以多址干扰为主的系统误码率.研究表明:较之一维时域扩频码或一维谱域扩频码,2D-OOC系统性能大大提高,在大信息量传输时,适当选择码长和码重,系统总容量可高达Tbits/s量级,性能优于基于1D-OOC的OWDM和OCDMA混合系统.

Configuration Research of 2D-OOC Signature Sequence Code for OCDMA System

For suiting the rapidly increasing requirement of communication, optical code division multiple access (OCDMA) technology has received the world-wide recognitions, because of its capacities of carrying heavy, bursty and asynchronous traffic. The key problems in its road to be actually applied are the maximum number of users it can contain and the bit error ratio (BER) of the system. Thinking of shortcomingof OCDAM system based on the one-dimensional optical orthogonal codewords (1D-OOC), such as using large bandwidth expansion or the need of complicated and not-yet-feasible optical processing, the scheme of two-dimensional optical orthogonal codewords (2D-OOC) code-designing is established, by terms of extending one-dimensional optical orthogonal codewordsto 2D-OOC. Focusing at the improvement in the maximum number of users and the bit error ratio, the two most important targets of the system optimization, the general performance of the OCDMA system with 2D-OOC has been discussed, the autocorrelation and the cross-correlation properties of the codes has been analyzed, the upper bound of the simultaneous number of users has been given, and particularly the bit error ratio of the system has been deeply researched. The results indicate that the number of simultaneous users that can be contained in this system will be much larger than that in the system with 1D-OOC under the same bandwidth expansion or the same BER requirement, and the total transmitting capacity of the system will reach the level of Tbits/s satisfying the requirement of BER less than 10 -9when the code length is longer than 43, which can be feasible easily now. Compared to the hybrid system of wavelength division multiplexing (WDM) and OCDMA with 1D-OOC, the general performance of 2D-OOC system will be comparable for the medium traffic, but for the heavy transmitting traffic, OCDMA system with 2D-OOC will perform much better than WDM +CDMA.