Projected parallel interference cancellation multiuser detector for asynchronous upstream OCDMA-PON

OCDMA is a promising candidate for Next Generation Passive Optical Networks (NG-PON). OCDMA-PON can potentially provide all customers with a Gb/s-cIass bandwidth upstream with inherent flexibility. Unfortunately OCDMA suffers from Multiple Access Interference (MAl) and various detection noises. To mitigate MAl we propose a novel parallel interference cancellation technique for incoherent DS-OCDMA that better exploits the positivity of the solution. The proposed PIC scheme incorporates this additional information into its structure. The proposed PIC detector is shown to outperform the conventional correlator detector, the decorrelator detector, the Linear Parallel Interference Cancellation (LPIC) detector and even the Linear Minimum Mean Square Error (LMMSE) detector. As a matter of fact, our detector achieves more than 1 dB enhancement in SNR at 10.3 average BER for 32 active users compared to the LMMSE detector. This gain can be used to reduce the code length required to support a higher number of users.