Performance Control of Incoherent Synchronous PPM-OCDMA Networks

Abstract

In this paper, the structure of an incoherent synchronous optical encoding–decoding technique utilizing Optical Code Division Multiple Access (OCDMA) network is introduced. Such technique is called Time Domain Encoding (TDE), which is based on Optical Delay Lines (ODLs). The paper analyzes the performance of OCDMA Bit Error Rate (BER) for different new efficient OCDMA codes. These codes are namely Modified Prime Code sequences (MPCs), Padded MPCs (PMPCs), new MPCs (n-MPCs), Double Padded MPCs (DPMPCs), Enhanced MPCs (EMPCs), and Weighted MPCs (WMPCs). The BER performance is evaluated with respect to the received optical power and the number of active users. While several noise sources can affect the system performance, the paper takes in the analysis the Multiple Access Interference (MAI) as the only source of noise. Furthermore, the Pulse Position Modulation (PPM) is used as a modulation technique to improve the system capacity and control the transmission power efficiency. Additionally, the Manchester encoding technique and the MAI Cancellation (MAIC) receiver are used simultaneously to enhance the BER performance. Finally, the results showed that the system BER performance is enhanced by controlling the pulse duration using the WMPC, and that the utilized WMPC sequence outperforms all the other MPCs family.