Performance Analysis of Two-Level Asynchronous Optical CDMA Systems Utilizing Wrapped OPPM

Abstract

In this paper the performance and the capacity of<br><br>two-level asynchronous incoherent optical CDMA (OCDMA) systems<br><br>employing wrapped overlapping pulse position modulation<br><br>(WOPPM) and optical AND logic gate receiver are analyzed. These<br><br>analyses are performed by considering the multiple access interference<br><br>as the main limiting factor. Because of the power limitation<br><br>in some laser sources, the same-symbol-power scheme for all users<br><br>is assumed. Optical orthogonal codes with the same length are assigned<br><br>to the users of each class. Considering the throughput as<br><br>constraint, the effects of the number of users in each class and the<br><br>weight of low-weight users on the performance of each class are<br><br>examined and the results are compared with the same-mark-power<br><br>case. Finally, the effect of WOPPM signaling parameters such as<br><br>overlapping index and total number of symbols on the error probability<br><br>of each class is investigated in the presence and in the absence<br><br>of throughput constraint. Our results show that when the multilevel<br><br>technique is employed inWOPPM OCDMA systems, one can<br><br>find solutions for some design problems that cannot be handled by<br><br>conventional one-levelmethods. In addition to this benefit, employing<br><br>this technique leads to a less complex transceiver structure.