An access optimization approach for FFH-OCDMA system's fiber Bragg gratings encoder

This paper suggests an adaptive 2-D Optical CDMA coding system based on one-coincidence frequency hopping (OCFH) code combined with an optical orthogonal code (OOC) in the format OCFH/OOC, suitable for the fast frequency hopping optical code division multiple access (FFH-OCDMA) channel, encoded by the Bragg gratings encoder with an aim to optimize the access network in terms of number of users and transmitted power. As wavelength hopping (WH) code, the OCFH code is herein adapted to the constraints of the encoder: the Bragg gratings chain put on the optical fiber. As the time spreading (TS) code, the code length bounds of the OOC and its new extended sequence derived from the introduction of run length constraints are given. The multiple access interference (MAI) of the resulting combined sequence is evaluated based on the number of coincidences and a performance comparison is made between the new congruence class of (9, 3,1)-OOC obtained and the previous well-known congruence class of (7, 3,1)-OOC.