A new Protocol for high Performance Fiber Optics Star Networks based on FDM Technique

Abstract

In an optical LAN based on linear topology there are important issues, as the connection of new nodes and the amount of cumulative losses encountered by optical signals, which make it difficult to meet the general requirements of LAN, such as expansibility, reliability and modularity. On the contrary the star topology shows a positive feature in terms of reliability and expansibility. This paper deals with a protocol conceived for fiber optics LANs based on coherent transmission. It is particularly suitable for implementation in a star topology, which allows both integration of services over the same network and high speed operation of the physical layer. Moreover, such protocol allows to avoid collision problems, which in general arise into a star topology network. In particular, this last problem is solved by the protocol on the ground of the knowledge of nodes Queue Status, which is achieved considering that in a star topology the star center is the only shared resource.By measuring the distance from nodes to the star center and communicating in each header the packets priority and the status of the node, it is possible to guarantee the continuity of the information flow in the star center. In such a way the influence of network propagation delay on protocol performance is reduced. The performance evaluation of the protocol in terms of delay a packet and the average throughput of the single node is presented and discussed.