In this tutorial overview, the principles, advantages, challenges, and practical requirements of optical orthogonal frequency division multiplexing (OFDM)-based optical access are presented, with an emphasis on orthogonal frequency division multiple access (OFDMA) for application in next-generation passive optical networks (PON). General OFDM principles, including orthogonality, cyclic prefix use, frequency-domain equalization, and multiuser OFDMA are summarized, followed by an overview of various optical OFDM(A) transceiver architectures for next-generation PON. Functional requirements are outlined for high-speed digital signal processors (DSP) and data converters in OFDMA-PON. A techno-economic outlook for such a “software-defined,” DSP-based optical access platform is also provided.

OFDM for Next-Generation Optical Access Networks

https://www.cs.uic.edu/~ygu/paper/udt-comnet-v3.pdf

UDT: UDP-based data transfer for high-speed wide area networks

The hybrid wireless-optical broadband-access network (WOBAN) is a promising architecture for future access networks. Recently, the wireless part of WOBAN has been gaining increasing attention, and early versions are being deployed as municipal access solutions to eliminate the wired drop to every wireless router at customer premises. This architecture saves on network deployment cost because the fiber need not penetrate each end-user, and it extends the reach of emerging optical-access solutions, such as passive optical networks. This paper first presents an architecture and a vision for the WOBAN and articulates why the combination of wireless and optical presents a compelling solution that optimizes the best of both worlds. While this discussion briefly touches upon the business drivers, the main arguments are based on technical and deployment considerations. Consequently, the rest of this paper reviews a variety of relevant research challenges, namely, network setup, network connectivity, and fault-tolerant behavior of the WOBAN. In the network setup, we review the design of a WOBAN where the back end is a wired optical network, the front end is managed by a wireless connectivity, and, in between, the tail ends of the optical part [known as optical network unit (ONU)] communicate directly with wireless base stations (known as ldquogateway routersrdquo). We outline algorithms to optimize the placement of ONUs in a WOBAN and report on a survey that we conducted on the distribution and types of wireless routers in the Wildhorse residential neighborhood of North Davis, CA. Then, we examine the WOBAN's routing properties (network connectivity), discuss the pros and cons of various routing algorithms, and summarize the idea behind fault-tolerant design of such hybrid networks.

Hybrid Wireless-Optical Broadband-Access Network (WOBAN): A Review of Relevant Challenges

Passive optical networks are used for fiber-to-the-home/curb/cabinet/building applications. Today, two PON variants with time-domain multiple access, GPON and EPON, are being used for mass roll-outs. WDM-PONs are the next step up from these PONs to accommodate traffic growth and new applications. This article analyzes WDM-PON variants and proposes they be used for a unified optical access and back-hauling network.

PON in adolescence: from TDMA to WDM-PON

Long-Reach optical access is a promising proposal for future access networks. This technology can enable broadband access for a large number of customers in the access/metro area, while decreasing capital and operational expenditures for the network operator. First, the paper reviews the evolutionary path of access networks and shows the drivers from technology and business perspectives for high bandwidth and low cost. A variety of research challenges in this field is reviewed, from optical components in the physical layer to the control and management issues in the upper layers. We discuss the requisites for optical sources, optical amplifiers, and optical receivers when used in networks with high transmission rate (10 Gbps) and large power attenuation (due to large split, transmission over 100 km and beyond, and propagation), and the key topological structures that allow to guarantee physical protection (tree-and-branch, ring-and-spur). Then, some relevant demonstrations of Long-Reach Optical Access Networks developed worldwide by different research institutes are presented. Finally, Dynamic Bandwidth Allocation (DBA) algorithms that allow to mitigate the effect of the increased control-plane delay in an extended-reach network are investigated.

Long-reach optical access networks: A survey of research challenges, demonstrations, and bandwidth assignment mechanisms

Feature Issue on
Optical Access Networks (OAN) The passive optical network (PON) is
an optical fiber based network architecture, which can provide much higher bandwidth
in the access network compared to traditional copper-based networks. Incorporating
wavelength-division multiplexing (WDM) in a PON allows one to support much higher
bandwidth compared to the standard PON, which operates in the "single-wavelength
mode" where one wavelength is used for upstream transmission and a separate one is
used for downstream transmission. We present a comprehensive review of various
aspects of WDM-PONs proposed in the literature. This includes enabling device
technologies for WDM-PONs and network architectures, as well as the corresponding
protocols and services that may be deployed on a WDM-PON. The WDM-PON will become a
revolutionary and scalable broadband access technology that will provide high
bandwidth to end users.

/pdf/wavelength-division-multiplexed-passive-optical-network-wdm-428jyy569l.pdf

Wavelength-division-multiplexed passive optical network (WDM-PON) technologies for broadband access: a review (Invited)

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.

/pdf/fair-queueing-with-service-envelopes-fqse-a-cousin-fair-2rfj1ion2o.pdf

Fair queueing with service envelopes (FQSE): a cousin-fair hierarchical scheduler for subscriber access networks

With the development of optical technology, the span of a broadband access network using passive optical network (PON) technology can be increased from today's standard of 20 km to 100 km or higher. As a result, we have the long-reach (LR) PON which not only has extended reach, but which can also support a large base of users by employing wavelength-division multiplexing (WDM) for its data transmissions. However, a major challenge in the LR-PON is that the propagation delay (for data as well as control signals) between the telecom central office (CO) and the end user is increased by a very significant amount. Now, traditional PON algorithms for scheduling the upstream transmission, such as dynamic bandwidth allocation (DBA) algorithms, may not be sufficient; actually, they may lead to degraded performance because of the long delay of the "control loop" between the CO and the users. This challenge motivates us to investigate a multi-thread polling algorithm to distribute the upstream bandwidth dynamically in the LR-PON. In this study, we analyze key parameters of the algorithm, such as initiating and tuning multiple threads. We then demonstrate the algorithm's advantage to decrease the average packet delay under varying offered loads.

Multi-Thread Polling: A Dynamic Bandwidth Distribution Scheme in Long-Reach PON

A control-plane architecture for supporting advance reservation of dedicated bandwidth channels on a switched network infrastructure is described including the front-end web interface, user and token management scheme, bandwidth scheduler, and signaling daemon. A path computation algorithm for bandwidth scheduling is proposed based on an extension of Bellman-Ford algorithm to an algebraic structure on sequences of disjoint non-negative real intervals. An implementation of this architecture for UltraScience Net is briefly described.

Control Plane for Advance Bandwidth Scheduling in Ultra High-Speed Networks

Systems and methods for preferentially assigning virtual machines (VMs) on a particular NUMA node with network queues on the same NUMA node are described. A load balancer process on a host assigns multiple VMs to network queues. The assignment of the VMs to a network queues is performed with a bias toward assigning VMs using a particular NUMA node to network queues on the same NUMA node. A scheduler on the host assigns VMs to NUMA nodes. The scheduler is biased toward assigning VMs to the same NUMA node as the PNIC and/or the same NUMA node as a network queue assigned to the VM.

Amitabha Banerjee

Papers

Wavelength-division-multiplexed passive optical network (WDM-PON) technologies for broadband access: a review (Invited)

Fair queueing with service envelopes (FQSE): a cousin-fair hierarchical scheduler for subscriber access networks

Multi-Thread Polling: A Dynamic Bandwidth Distribution Scheme in Long-Reach PON

Control Plane for Advance Bandwidth Scheduling in Ultra High-Speed Networks

NUMA I/O aware network queue assignments