Optical CDMA via temporal codes

Abstract

We provide an analysis to the performance of Optical Orthogonal Codes(OOC) in an Optical Code Division Multiple Access(CDMA) network by considering the probability distribution of the interference patterns. We show that the actual performance is close to a previous estimate. We also consider a less structured temporal code in which the code words are allowed to overlap at two pulse positions. We obtain the bit error probability for this class of codes for two cases: with and without optical hard-limiting at the receivers. We show that this code may increase the number of users in the network considerably without a significant loss in the performance. We also provide a simple partial construction scheme for this code.

Analytical comparison of various fiber-optic CDMA receiver structures

“…We adopt the notation in [5] to model the interference patterns. We denote by the number of interfering pulses received in th pulse position and by the vector of received interference.…”

“…Assuming interfering pulses, pattern can be produced in ways each with probability . Therefore, if is the probability of error given interference pattern , then error probability can be expressed as (3) where from [5] (4) where depends on receiver structure as well as interference pattern .…”

“…We will denote by the number of ways that only out of boxes are filled with distinguishable balls. We know from [5] that is on the form of We note that . Therefore,…”

“…A spread spectrum multi-access system, using optical orthogonal codes (OOCs) as spreading codes, was proposed in [1] for intensity modulation/direct detection OOK optical signals. Performance analysis of such systems with various receiver structures was the subject of many articles [2], [5]- [7]. Salehi and Brackett [2] analyzed the system performance taking into account channel interference and have shown the usability of OOCs in ideal interference limited cases.…”

Introduction to Optical Communications

“…hundreds of users; enhanced bandwidth of 100 + Gbps; and higher scalability at long distances such as tens or hundreds of kilometres for LANs and metropolitan area networks (MAN). Significant progress of OCDMA research has been achieved worldwide in recent years, including several different OCDMA schemes that have been proposed based on different choices of sources [54,66,70,82], coding schemes [37,59,67] and detections [76,80,[83][84][85][86][87] which will be discussed in detail in this book through the following chapters.…”