We study networks based on torus topologies enhanced with additional, arbitrary assigned links. We develop a method for analyzing the expected number of hops which can be applied to any torus topology with randomly assigned extra links when the simplest greedy routing is used. Using this method, we study the following topologies with extra links: one-dimensional unidirectional and bidirectional torus (i.e., ring), and two-dimensional bidirectional and unidirectional torus (e.g., bidirectional Manhattan network and Manhattan street network). We also show how these results can be extended to some non-torus topologies with extra links, such as the bus and the two-dimensional grid. From our analysis we find that the expected number of hops in a D-dimensional N-node torus with extra links grows as O(/sup D+1//spl radic/N) and that it can be reduced to O(/sup 2D//spl radic/N) with the orthogonal assignment of extra links.

In this paper, we study the benefits of wavelength translation in all-optical networks providing clear channel circuit-switching among users. We first establish approximate analytical models for a static-routing circuit-switched network with an arbitrary topology, both with and without wavelength translation. We then study the performance of the nonblocking centralized switch, the mesh-torus network and the ring network, using the analytical models and simulation results. It is shown that the analytical models match the simulation results very well in the case of the centralized switch and the mesh network. The results of our study also show that the benefits of wavelength translation are modest for the centralized switch and the ring network. On the other hand, the results show that wavelength translation can significantly improve the performance of a large mesh-torus network.

We propose a new scheme for optical signal routing within linear lightwave network (LLN) subnets. The LLN is a fiber optic network which performs only linear operations on optical signals: power combining, splitting and possibly linear optical amplification. The LLN can be partitioned into several subnets where each subnet is a tree providing full broadcast among all stations connected to it. We study the synchronization problem that exists in these subnets which prevents efficient implementation of time division multiple access schemes for sharing a common broadcast medium. A solution to this problem is proposed, based on a new optical signal routing scheme, called rooted routing. The impact of rooted routing on power losses is analyzed, and an approach for minimizing power loss in LLNs with rooted routing is presented. It is shown that when link and excess losses are small, rooted routing power budget can be made close to the power budget yielded by the original, shortest path routing scheme. It is also shown that rooted routing power budget can be significantly improved using a single optical amplifier.

The authors study the effect of channel sharing on the performance of multihop lightwave networks when channel sharing is achieved by using a time-division multiple-access (TDMA) technique. They present a result which gives an upper bound for the throughput that can be achieved with any virtual topology that can be established with N stations assuming that the traffic distribution is uniform and that all virtual links have the same capacity. Using this result they determine the optimal degree of channel sharing that maximizes throughput. They also determine the optimal degree of channel sharing when the criterion is to maximize the network power, which is defined as a ratio of throughput and delay.>

Given that many optical fibers can be economically packaged within a single cable, the design of communication networks that exploit multifiber topologies is considered. A network architecture that uses the multifiber tree topology to provide high-speed datagram and circuit-switching communication services to a large population of stations is presented. Using a combination of space-, wavelength-, and time-division multiplexing, this network architecture provides all-optical transmission media to its stations and can interconnect several thousand stations in a metropolitan region without the need for optical amplification or electrooptical signal regeneration.>

The authors propose a new scheme for optical signal routing within linear lightwave network (LLN) subnets. They study the synchronization problem that exists in these subnets which prevents efficient implementation of time division multiple access schemes for sharing a common broadcast medium. A solution for this problem is proposed, based on a new optical agent signal routing scheme, called rooted routing. The impact of the rooted routing on power losses is analyzed, and an approach for optimizing the power losses in LLNs with rooted routing is presented. It is shown that when the link and excess losses are small, the optimal power budget is close to that when the original, shortest path routing scheme is used. It is also shown that the power budget in LLNs with rooted routing can be significantly improved using a single optical amplifier.>