In this paper we present an in-depth review on the trends and the directions taken by the researchers worldwide in Optical Code Division Multiple Access (OCDMA) systems. We highlight those trends and features that are believed to be essential to the successful introduction of various OCDMA techniques in communication. Systems and data networks in near future. In particular we begin by giving a comprehensive review on the constructions of optical orthogonal codes (OOC). In our system study we first focus and discuss on various OCDMA techniques such as 1-D, 2-D and spectrally-encoded ultra short light pulse CDMA, and discuss their pros and cons. A comprehensive discussion takes place on all important aspects of each OCDMA technique. In particular, we elaborate on enabling technologies that are needed prior to full scale consideration of OCDMA in communication systems. We extend our discussion to various data networks, including fiber-based and WIRELESS to indicate the directions and the applications that OCDMA systems are considered for. It is believed that OCDMA once fully developed and matured will be an inseparable part of advanced optical communication systems and networks due to its various desirable features and functionalities, in not so distant future.

A new detection technique based on subtraction technique is proposed for a hybrid of subcarrier multiplexed spectral-amplitude-coding optical code division multiple access (SCM SAC-OCDMA) of a point-to-point system. SAC-OCDMA is used because of its ability to cancel the multiple access interference (MAI) when code sequences with fixed in-phase cross correlation are used. On the other hand, the SCM technique is able to enhance the channel data rate of OCDMA systems. This hybrid scheme is proposed for the purpose of combining the advantages of both schemes. As a result, the hybrid system is robust against interference and is much more spectrally efficient. A new code structure for SAC-OCDMA system based on double weight (DW) code family is employed. The simulation results show that the proposed new subtraction detection technique improves the system performance significantly compared to the conventional subtraction detection technique.

As WIRELESS networks with high data rate get widely deployed, improving the performance of TCP over these networks plays vital role. WIRELESS link losses have dramatic adverse impact on TCP performance due to the difficulty in distinguishing the congestion losses from WIRELESS link losses. We first, studied the various existing Bandwidth Estimation Algorithms over the WIRELESS networks. In this paper, we propose an enhanced bandwidth estimation technique with congestion control algorithms to improve TCP performance over WIRELESS link with random loss. We propose, a new technique called TCP- BWIW to estimate the bandwidth and the congestion window is set accordingly. The performance of TCP-BWIW is analyzed, and it mitigates the Network congestion.