Savings in switching costs of an optical cross-connect can be achieved by grouping together a set of consecutive wavelengths and switching them as a single waveband. This technique is known as waveband switching. While previous work has focused on either uniform band sizes or nonuniform band sizes considering a single node, in this paper we focus on the number of wavebands and their sizes for ring topologies. First, we show that such solutions are inadequate when considering the entire network. We then present a novel framework for optimizing the number of wavebands in a ring network for deterministic traffic. The objective of the Band Minimization Problem is to minimize the number of nonuniform wavebands in the network while using the minimum possible number of wavelengths. We show that the problem is NP-hard and present heuristics for it. We then consider a specific type of traffic, namely all-to-all traffic, and present a construction method for achieving the minimum number of wavebands in the ring. Our results show that the number of ports can be reduced by a large amount using waveband switching compared to wavelength switching, for both all-to-all traffic and random traffic. We also numerically evaluate the performance of our waveband design algorithms under dynamic stochastic traffic.

We consider routing multicast traffic requests originating in a hierarchical optical network architecture with multiple access networks attached to a core network. A request originates in a source access network (also called collection network) and include multiple destinations in different access networks (also called distribution networks). We call them together as collection-distribution networks (CDN). The connection points between a CDN and the core network is an edge node which can groom several multicast connections together. In such an architecture, given a set of multicast requests, our goal is to maximize the amount of multicast destinations and bandwidth served. Therefore, we formulate an optimization problem with an objective of maximizing the product of bandwidth-number of destinations according to partial multicast service discipline. We show that this is an NP-hard problem and present a suboptimal and a heuristic algorithm. We develop a lower bound on the performance. We present numerical results and show that our algorithms achieve a very close performance to the lower bound.

Waveband switching saves port costs in optical crossconnects by grouping together a set of consecutive wavelengths and switching them as a single waveband. Previous work has focused on either uniform band sizes or non-uniform band sizes considering a single node. In this paper, we show that such solutions are inadequate when considering the entire network, and present a novel framework for optimizing the number of wavebands in a ring network for deterministic traffic. We then consider a specific type of traffic, namely, all-to-all traffic and present bounds and heuristic solutions for the problem. Our results show that the number of ports can be reduced by a large amount using waveband switching compared to wavelength switching. We also numerically evaluate the performance of our waveband design algorithms under dynamic stochastic traffic.

Wireless infrastructure networks that provide ubiquitous connectivity to mobile nodes in metro areas are becoming increasingly popular. The nodes in such backbone networks are often equipped with multiple transceivers to allow for simultaneous transmissions in multiple non-overlapping channels. In this paper, we develop an analytical model for evaluating the throughput and delay performance of wireless infrastructure networks employing Slotted Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) over multiple channels. The analytical model, which takes into account the correlation due to multi-hop transmissions, approximates the performance observed through simulations accurately.

The blocking performance of limited-reconflgurable all-optical networks is investigated in this paper. Reconfigurability is achieved by reconflgurable optical add-drop multiplexers (ROADMs) and tunable transponders. An analytical model is developed adopting a share-per-node model for the sharing of transponders within a reconfigurable node. The set of wavelengths that can be added/dropped at a reconfigurable node depends on the constraints of ROADMs as well as the (possibly limited or narrowly) tunable transponders. The size of the wavelength set to which a transponder is tunable (tuning range), and the number of transponders are the key parameters that affect the blocking. A lightpath request can be established depending on the transponders' ability to tune to the available wavelengths along the route. We call this constraint as wavelength termination constraint. Both analytical and simulation results show that narrowly tunable transponders achieve a similar performance as widely tunable transponders. The effect of the number of transponders or the number of ports of a ROADM on blocking is also investigated.

In this paper, we investigate the blocking performance of all-optical ring and mesh networks with Reconfigurable Optical Add-Drop Multiplexers (ROADMs) and tunable transponders. The ROADMs and transponders together determine the number and set of wavelengths that can be added/dropped leading to a wavelength termination constraint in addition to the well-known wavelength continuity constraint. We develop an analytical model for the blocking probability by accounting for both constraints and validate the model using simulation results. Specifically, a model for computing the blocking probability in a reconfigurable network of arbitrary topology wherein the number and tunability of the transponders are given parameters is presented. It is found that narrowly tunable transponders with a tuning range of about 4 in a 32-wavelength network provides nearly as good a performance as widely tunable transponders (tunable over the entire range of wavelengths), for a wide range of loads and number of transponders. Moreover, waveband assignment to narrowly tunable transponders is found to be a factor in some cases, and we present some results for two different assignment schemes.