Design And Research Of Address Code In OCDMA System

Optical code division multiple access(OCDMA)technology has received wide attention due to its inherently high confidentiality,which offers significant advantages in different transmission rates and different quality of service(QoS).One of the main reasons of the current OCDMA technology has not been commercialized is that it can not find a high-value optical code set.Therefore,the main content of this thesis is the design and performance analysis of the excellent optical address code.The main work is as follows:(1)A new two-dimensional optical orthogonal code(2D-OOC)with a large code-word capacity and excellent error performance is designed.The expand secondary prime code/mutually orthogonal latin square(ESPC/MOLS).Under the same code-word parameter,when the number of wavelengths q is the prime power,the capacity of the ESPC/MOLS codeword is up to q times that of the extended secondary prime code/one coincidence sequence(ESPC/OCS).The numerical simulation is carried out after deriving the error rate formula of the code.The error rate of ESPC/MOLS under the same code-word parameter can be lower than that of the similar 2D-OOC.The OCDMA system simulation experiments conducted in Optisystem show that: A system with ESPC/MOLS can achieve an eye diagram that is more positive and clear with a lower bit error rate than ESPC/OCS.Finally,in the two-dimensional electric domain codec system built in the laboratory,the transmission experiment of the code at the signal rate of312.5Mb/s is completed,and the two-way user eye diagram is clear and correct.It is preliminarily verified that the experimental system using ESPC/MOLS at low rate can accurately transmit user information.(2)An extended internal recycle prime code(EIRPC)for spectral amplitude codec(SAC)systems was designed.The use of balance detection eliminates multiple access interference between the code-words.After deriving its bit error rate under the influence of noise,the three-dimensional surface map of the system error rate with the code weight p and the number of concurrent users K is plotted,which is a way for the SAC-OCDMA system to quickly find a certain communication quality.The best combination of code weight and maximum concurrent users provides new ideas.Subsequent performance comparisons with similar SAC in the presence of noise,EIRPC has a shorter code length and a smaller bit error rate under the same code-word parameters.Finally,the influence of different noises on the performance of the receiver with the effective power of the receiver in the SAC-OCDMA system using this code issimulated and analyzed.This result provides a feasible way to effectively reduce the influence of different noise on the bit error rate of SAC-OCDMA system.(3)A new two-dimensional variable weight optical orthogonal code(2D-VWOOC)suitable for multi-QoS-OCDMA systems is designed by using the optimal variable weighted optical orthogonal code(OVWOOC).The numerical simulation of the error rate formula caused by multiple access interference under different code weights is analyzed and deduced.The results show that in the same group of VWOOC: An address code having a larger code weight has a lower bit error rate;The bit error rate of the same code decreases as the number of code weights in the system increases.Finally,in the Optisystem,the two codewords generated when the shortest code length is selected are used to perform the two-dimensional transcoding and grading code division multiple access simulation experiment.Obtaining an eye pattern with a code weight of 5 and a code weight of 3 is more clear than the end,and the error rate between the two codewords is nearly ten orders of magnitude different.It is preliminarily proved that the OCDMA system using OVWOOC/MOLS can provide multiple QoS services for the uplink users.