Design and analysis of spreading code and transceiver architectures for optical CDMA networks

Abstract

In this thesis, firstly we have reviewed both previous and current state of optical CDMA (OCDMA) technologies. Search for appropriate spreading codes is one of the main challenges of OCDMA applications and hence is an important topic which is heavily addressed in the literature. Existing codes have restrictions on code-lengths, weights and correlation properties where the number of generated codes is severely limited. Secondly, we have paid a particular attention to proposing a novel spreading code, hereby referred to as Double Padded Modified Prime Code (DPMPC) which suppresses the multiple-access interference and also enhances the network capacity. Then, we have applied the DPMPC to both coherent and incoherent time-spreading OCDMA transceivers and analysed their overall performances. We have also proposed novel transceivers which are power-efficient, simple and able to accommodate great number of simultaneous users. Accordingly, an advanced two-dimensional frequency-polarization modulation for OCDMA has been introduced, for the first time, to elevate the system security as well as the performance. Finally, the application of OCDMA in the passive optical network leading to the OCDMA-PON architecture has been established including the optical line terminal and network units. Since Internet protocol is currently the dominant network protocol, IP-over-OCDMA network node configuration ha