High Performance with Avalanche Photodiode in Wavelength/Time Optical Code Division Multiple Access

Abstract

In order to increase the number of users as increasing the data rate and transmission distance, then to reduce the impact of multi-access interference (MAI) and the effect of phase-induced intensity noise (PIIN). This study proposed the utilizing of an avalanche photodiode (APD) on two-dimension optical code division multiple access (2-D OCDMA). APD detector is more sensitive than positive-intrinsic-negative (PIN) photodiode, due to its inherent gain that increases the signal to noise ratio (SNR) of the system by amplifying the received signal prior to proceeding to next stage. In this research, an improvement of realizable system capacity APD performance of different gain applied for Wavelength/Time modified double weight (MDW) code for cardinality, bit error rates (BER) and noise interference are analyzed. MATLAB is utilized as a software for theoretical results to study the APD gain effect upon the probability density function (PDF) and SNR performance. The results in very good approval indicate that 95.45% cardinality improvements compare to 2-D MDW code with PIN at 1.25 Gbps data bit rate. The Psr = -14 dBm for 500 active users by using APDs with gain =5, but 5 dBm effective receive power for PIN error floor 10-9 for 500 users. The usage of APD over (PIN) photodiode provides a high performance for a long transmission distance and high data bit rate that improved in the simulation for real environment by using the Optiwave software version 11.0. Seemingly, the system supports more no. of users, less bit error rate, and large data rate transmission.