Abstract
This paper presents a new family of spreading code sequences called hybrid prime code (HPC), to be used as source code for the optical code division multiple access (OCDMA) network for large network capacity. The network capacity directly depends on the number of available code sequences provided and their correlation properties. Therefore, the proposed HPC is designed based on combining two or more different code words belonging to two or more different prime numbers. This increases the number of code sequences generated. The code construction method utilized allows the generation of different code sets, each with different code length and weight, according to the number of prime numbers used. In addition, the incoherent pulse position modulation (PPM) OCDMA system is proposed based on the HPC code. Furthermore, the bit error rate (BER) performance analysis is introduced versus the received optical power and the number of active users. Moreover, the error vector magnitude (EVM) is calculated versus the optical signal-to-noise ratio. This work proves that using two prime numbers simultaneously generates far more codes than using prime numbers separately. It also achieved an OCDMA system capacity higher than the system that uses the optical orthogonal codes (OOCs), modified prime codes (MPCs) families, and two code families with separate simultaneously prime numbers, at a BER below 10−9 which is the optimum level.
Highlights
In the last three decades, there were two main categories of optical orthogonal codes, based on (0, 1) logic, and were introduced into the optical code division multiple access (OCDMA) networks
The main objective of this study is to propose a new code family called hybrid prime codes (HPC) that is not related to the modified prime codes (MPCs) and their method of construction but only depends on the code words of the PC
orthogonal codes (OOCs), MPC, active users based on the proposed HPC
Summary
In the last three decades, there were two main categories of optical orthogonal codes, based on (0, 1) logic, and were introduced into the optical code division multiple access (OCDMA) networks. The first code category refers to the optical orthogonal codes (OOCs) and is designed with low off-peak, auto- and cross-correlation properties for the purposes of frame synchronization and minimum interference [1,2,3,4,5,6,7,8,9]. The second one refers to the prime codes (PCs) and is designed to sacrifice the auto-correlation property [10,11,12,13,14,15,16,17,18,19,20,21]. All code sequences are orthogonal and share the same available bandwidth such as the OOCs, MPCs, and other spreading codes in the literatures.
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