Jane M. Simmons

High-density micromachined polygon optical crossconnects exploiting network connection-symmetry

Optical-layer crossconnects with high port count appear to be emerging as key elements for provisioning and restoration in future wavelength-division-multiplexed networks. We demonstrate here a means of achieving high-density optical crossconnects utilizing free-space micromachined optical switches that exploit connection-symmetry in core-transport networks. The micromachined polygon switches proposed here are strictly nonblocking. Measured insertion losses of 3.1-3.5 dB for a 16/spl times/16 (8/spl times/8 bidirectional) switch suggest the promise of scaling to large port count.

On the value of wavelength-add/drop in WDM rings with uniform traffic

Summary form only given. For WDM SONET ring networks transporting uniform traffic, we have devised a traffic-bundling methodology that enables one to both quantify the maximum terminal-equipment savings attainable using wavelength-add/drop, and to produce constructions that achieve these optima. Maximum terminal-equipment savings are seen to increase swiftly, over the region of interest, with both network size and inter-node demand.

Optical crossconnects of reduced complexity for WDM networks with bidirectional symmetry

One promising approach to provisioning and restoration in long-haul wavelength-division-multiplexing (WDM) networks is to deploy a mesh of optical crossconnects that operate on individual wavelengths. As wavelength-count and traffic demand rapidly increase, however, this approach will likely require high-port-count optical crossconnects that severely strain the capabilities of known device technologies. Thus, it is critical to devise ways to build large crossconnects from a small number of constituent switches, each with reduced port count. We present a general means of accomplishing this for networks, such as current long-haul networks, that demonstrate bidirectional symmetry. We describe a broad class of symmetry-exploiting architectures that yield N/spl times/N crossconnects, both rearrangeably nonblocking and strictly nonblocking, using constituent switch fabrics no larger than N/2/spl times/N/2. By exploiting connection-symmetry, these architectures reduce the number of such N/2/spl times/N/2 fabrics by 30%-50% compared with corresponding fully connected three-stage Benes and Clos switch structures.

The value of optical bypass in reducing router size in gigabit networks

With the expected explosive growth in data traffic, the required processing demands at network nodes, e.g., in routers, will likely present a significant bottleneck. Optical bypass potentially alleviates this bottleneck by allowing a wavelength to bypass a node if it contains no traffic that needs to be processed there. We explore the value of optical bypass in gigabit networks by measuring the fractional decrease in required router size one can expect. We consider both ring and mesh topologies, and both uniform and distance-dependent traffic. We show that the reduction in router size can be very significant, with the fractional savings increasing as the size of the network increases and the amount of traffic increases, indicating that this technique will scale well in future networks.

Proof of correctness of ATM retransmission scheme

Abstract The ITU has designed a poll-based retransmission scheme as part of the Service Specfic Connection Oriented Protocol for ATM systems. The basic scheme consists of the transmitter periodically sending polls to the destination indicating which frames have been sent, and the receiver responding with a status message indicating which of these frames have not been received. Many additional features have been included in the scheme in order to reduce the retransmission delay and prevent unnecessary retransmissions. With the added complexity of these features, it is not readily apparent whether the scheme operates correctly. In this paper, it is shown that the scheme does satisfy the liveness and safety: the source can continue forever to accept frames for transmission, and all frames are eventually delivered in proper sequence at the destination, assuming that certain conditions hold. In addition, it is shown that unnecessary retransmissions do not occur.

Optical regional access network (ORAN) project

The DARPA-sponsored ORAN project is an architectural study of economically providing broadband wavelength-division multiplexing access to high-end users. The ORAN architecture is a scalable, flexible, cost-effective access network that delivers both huge bandwidth and high degree of upgradability.

Architectural advantages of WDM technology in access networks

The flexibility and scalability of a WDM access architecture have been discussed. WDM will play an important role in deploying access networks that can meet future customer demand in both the business and residential markets.

Connection-symmetric micromachined polygon optical crossconnects for WDM lightwave networks

Optical crossconnects are likely to emerge as critical network elements for provisioning and restoration in core WDM networks. The chief physical challenge facing these elements is that of scalability to high port-count. We demonstrate a route to achieving high port count by exploiting connection-symmetry in micromachined polygon switches. Insertion losses as low as 3.1 ~ 3.5 dB for a 16 x 16 (8 bi-directional) switch suggest the promise of scaling to large port count.