Passive optical network (PON) is one of the most successful broadband access architectures being deployed worldwide. PONs provide high capacity, increased reach, and low-power consumption at a very reasonable cost, on par with the cost of DSL deployments today. This paper provides an overview of present and emerging PON technologies, and discusses PON's important role in the evolution of optical access from the architectural perspective. While describing the evolution of optical access architecture, we present two important integration options: optical+wireless access integration and metro+access integration. Potential PON capacity upgrades are discussed with special emphasis on achieving a seamless upgrade. We evaluate different PON evolution strategies in the context of next-generation PON, where gradual, demand-based migration demonstrates a number of significant benefits.

The Passive Optical Network (PON) is an attractive solution for high-bandwidth access networks. In the context of a broadband access network, the term open access implies the ability of multiple service providers to share the deployed access network infrastructure to make services available to the end users. Multiple services may thereby be delivered over a shared access channel. Open access requires fairness in terms of throughput, delay, jitter, and other network parameters in the access channel among the sharing entities, namely service providers and end users. Since the traffic in an access network is very bursty, an access network may be frequently subjected to high loads for certain durations of time. Meeting the above fairness requirements under such conditions is therefore very challenging. In this study, we first motivate the problem of meeting fairness requirements simultaneously to both service providers and users, which are located at opposite ends of an access channel. We then investigate the importance of two different sets of Service-Level Agreements (SLAs), which we call Dual SLAs. After formulating a mathematical model, we propose an efficient scheduling algorithm to meet Dual SLAs which is based on the well-known concept of max-min fairness. We then demonstrate the effectiveness of our proposed algorithm through simulations using a discrete-event-simulator-based PON set-up, which compares the fairness of the Dual-SLA scheduling algorithm with that of other traditional fair queuing algorithms such as Deficit Round Robin (DRR)

Ethernet passive optical networks (EPONs) are an attractive solution for meeting the broadband access requirements of residential users. Open access is a regulatory requirement in many countries which mandates that the access infrastructure must be open to various service providers for free competition. Thus, different service providers may cater services to same or different users using the same shared access channel. Open access demands fairness in the use of network resources among sharing entities, namely service providers and end users. In this study, we investigate scheduling algorithms for fair bandwidth sharing in the context of open access for EPONs.

Integrated circuits (ICs) must be robust to manufacturing variations. Circuit simulation at a set of worst case corners is a computationally efficient method for verifying the robustness of a design. This paper presents a new statistical methodology to determine the worst case corners for a set of circuit performances. The proposed methodology first estimates response surfaces for circuit performances as quadratic functions of the process parameters with known statistical distributions. These response surfaces are then used to extract the worst case corners in the process parameter space as the points where the circuit performances are at their minimum/maximum values corresponding to a specified tolerance level. Corners in the process parameter space close to each other are clustered to reduce their number, which reduces the number of simulations required for design verification. The novel concept of a relaxation coefficient to ensure that the corners capture the minimum/maximum values of all the circuit performances at the desired tolerance level is also introduced. The corners are realistic since they are derived from the multivariate statistical distribution of the process parameters at the desired tolerance level. The methodology is demonstrated with examples showing extraction of corners from digital standard cells and also the corners for analog/radio frequency (RF) blocks found in typical communication ICs.

In this paper, we propose and investigate the characteristics of a fair queueing with service envelopes (FQSE) algorithm-a hierarchical fair-share scheduling algorithm for access networks based on a remote scheduling system such as Ethernet passive optical networks (EPON) or cable TV network. FQSE is designed to overcome the limiting factors of a typical remote scheduling system such as large control-plane delay, limited control-plane bandwidth, and significant queue switch-over overhead. The algorithm is based on a concept of service envelope-a function representing the fair allocation of resources based on a global network condition called satisfiability parameter (SP). We define properties of cousin-fairness and sibling-fairness and show the FQSE to be cousin-fair. FQSE is unique in that it is the only hierarchical algorithm that is simultaneously cousin-fair. Furthermore, we show the necessary techniques to adapt FQSE to variable-sized packet-based networks. We analyze FQSE performance in EPON serving 1024 independent queues and demonstrate FQSE's ability to provide guaranteed bandwidth to each queue and to share the excess bandwidth fairly.