Abstract

In this paper, we present a novel multirate, differentiated quality of service (QoS) optical CDMA (OCDMA) system using multilevel signaling technique. The emphasis is on OCDMA systems employing multi-length variable-weight optical orthogonal codes (MLVW-OOC) as signature sequence. We begin by presenting a two-class variable-weight OCDMA system in which all users have the same energy level in one bit duration. As a consequence, high weight users transmit their corresponding optical pulses at a lower power while low weight users transmit their corresponding optical pulses at a higher power level. We show that using this multilevel signaling technique, while employing the well known optical AND logic gate receiver structure, we achieve a considerable improvement in the performance of low-weight (high-power) users while the performance of high-weight (low-power) users not altered in comparison to one-level system. In the next step, we indicate that by using the recently introduced multistage receiver structure, which employs advanced optical logic gate elements, interferences at different power levels are distinguishable so that the performance of both high-weight and low-weight users are improved. Furthermore, we employ multilevel signaling technique in OCDMA system based on MLVW-OOC (multirate, differentiated QoS system). We show that using multilevel signaling technique in such a system results to the performance improvement. To analyze the performance of the system we obtain a closed-form relation expressing an upper bound on the probability of error of the system. Finally, to validate the upper bound, the analytical results are compared to the results of system simulation. The numerical closeness between the analytical and system simulation reveals the tightness of the obtained upper bound, hence making them quite useful in evaluating the above system's performance.

© 2009 IEEE

PDF Article

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription