# A New Hybrid Prime Code for OCDMA Network Multimedia Applications
## 2 Literature Review  
The main disadvantage of the 1D code is the need for a long code length for a large system capacity, where a large bandwidth is used in spectral coding and ultrashort pulses have to be used in temporal coding. Various 2D schemes are proposed to circumvent this problem. The 2D code can be constructed through various combinations of time, spectral, and space. There has been much research into the 2D spectral/time, spectral/space, and space/time domains. One of the most popular schemes is the MPC. In this scheme, different data bits are temporally spread by using optical delay lines for the incoherent OCDMA networks. In this section, we will present the most important previous research, as well as what has been accomplished in each research. This will lead us to present the idea and importance of the proposed code. In [34], the design of a 2D temporal/spatial incoherent OCDMA system is presented based on matrix codes with experimental results. The proposed system BRE performance was compared with the performance of the other system which uses the temporal codes. The results showed that the system performance based on the proposed designed code is better than the systems that use other codes. This is due to the lower losses with no side lobes in auto-correlation property. In [35], the authors proposed a new set of 2D wavelength/time codes with orthogonal properties in both domains for the OCDMA network. This code set was generated by an array of fiber gratings and was constructed based on the expansion operation from the 1D to 2D Hamming correlation. The BER performance was derived theoretically in terms of only the MAI and all other noise sources are neglected. The numerical simulations proved that the BER was improved compared with the BER of the systems that use other codes when using the smallest number of wavelength sets. In [36], the generation of a 2D pseudo-orthogonal code sequence was presented using the optimum Golomb rules. The authors analyzed the BER performance of a synchronous OCDMA system using 2D wavelength/time codes. It was shown that this code has higher cardinality and good spectral density than the linear code sequence. In [37], the spatial/spectral codes and corresponding system architecture were presented. The developed code was constructed based on two 1D M-sequences. The detection operation at the receiver was performed using only a binary multiplier. The authors proved that these codes have better BER performance than 1D M-sequence code if the number of active users is increased in the network. However, the MAI limits the system performance because of the dependency on the 1D M-sequence for the code construction. In [38], a new code family named 2D projection code was proposed with a balanced detection receiver. The code construction was based on the projection of 2D code into 1D wavelength code. The MAI was eliminated using the balanced detector. The BER performance was improved at the higher number of active users compared with the differential detection techniques. In [39], a 2D wavelength/time OOCs family was constructed for asynchronous OCDMA systems. These codes have more flexibility than the conventional 2D codes relative to the code size. The system performance based on the Markov chain technique was analyzed. The authors proved that this code provides better BER performance than the others, and the number of active users is dependent on the code size. In [40], the authors developed a 2D spatial/spectral code and used a MAI cancellation technique to enhance the BER performance. This code family was constructed based on a 1D perfect difference code and was named 2D perfect difference code. Moreover, the transceiver architecture was presented based on this 2D code and the results indicated that this system can accommodate more active users than the 2D M-sequence codes. In [41], the authors combined one-coincidence frequency hop code (OCFHC) and OOC to demonstrate a new code called OCFHC/OOC. In this code, each code word used a single wavelength.