Performance Analysis of Slotted ALOHA Random Access Packet-Switching Optical CDMA Networks Using Generalized Optical Orthogonal Codes and M-ary Overlapping PPM Signaling

In this paper we study slotted ALOHA random access optical code division multiple access packet-switching networks with a chip-level receiver structure. We use generalized optical orthogonal codes (GOOCs) and the overlapping pulse position modulation (OPPM) signaling technique to improve system performance. The impact of physical layer parameters such as the GOOC cross-correlation value and the OPPM overlapping index on key performance benchmarks such as network throughput and delay are analyzed. We also study the stability of the network based on the number of backlogged users, using the expected state drift. It has been shown that using GOOC instead of strict optical orthogonal codes improves the network average delay and throughput. Moreover, by comparing M-ary OPPM and conventional OOK signaling with a fair criterion we have demonstrated that OPPM signaling can substantially improve both steady state and transient network characteristics. This improvement can be obtained without introducing additional complexity in the receiver and transmitter structure.