Nishaanthan Nadarajah

Protection switching and local area network emulation in passive optical networks

This paper proposes and experimentally demonstrates an automatic-protection-switching (APS) mechanism against distribution fiber breaks in passive optical networks (PONs). The protection of optical-network units (ONUs) that are located at the customer premises is carried out by monitoring the distribution fiber using the traffic that is transported among the customers in the PON. This configuration emulates a local area network (LAN) over the existing PON while facilitating the switching of signal transmissions to a predetermined protection path in an event of a distribution fiber break. As failure detection and APS are performed independently by each ONU in a distributed manner, the processing complexities and delays are reduced at the central office (CO). The restoration of the traffic transported between the CO and an ONU in the event of the distribution fiber break is performed by interconnecting adjacent ONUs and carrying out signal transmissions via an independent but interconnected ONU. Such a protection mechanism enables multiple adjacent ONUs to be simultaneously protected by a single ONU utilizing its maximum available bandwidth. This paper experimentally verifies the feasibility of the proposed protection mechanism in conjunction with two different LAN-emulation schemes with a 1.25-Gb/s upstream baseband transmission to the CO and a 155-Mb/s LAN data transmission on a radio-frequency carrier. The experimental results obtained from both schemes are compared, and the power budgets are calculated to analyze the scalability of each scheme.

Novel schemes for local area network emulation in passive optical networks with RF subcarrier multiplexed customer traffic

This paper proposes two novel optical layer schemes for intercommunication between customers in a passive optical network (PON). The proposed schemes use radio frequency (RF) subcarrier multiplexed transmission for intercommunication between customers in conjunction with upstream access to the central office (CO) at baseband. One scheme employs a narrowband fiber Bragg grating (FBG) placed close to the star coupler in the feeder fiber of the PON, while the other uses an additional short-length distribution fiber from the star coupler to each customer unit for the redirection of customer traffic. In both schemes, only one optical transmitter is required at each optical network unit (ONU) for the transmission of customer traffic and upstream access traffic. Moreover, downstream bandwidth is not consumed by customer traffic unlike in previously reported techniques. The authors experimentally verify the feasibility of both schemes with 1.25 Gb/s upstream baseband transmission to the CO and 155 Mb/s customer data transmission on the RF carrier. The experimental results obtained from both schemes are compared, and the power budgets are calculated to analyze the scalability of each scheme. Further, the proposed schemes were discussed in terms of upgradability of the transmission bit rates for the upstream access traffic, bandwidth requirements at the customer premises, dispersion tolerance, and stability issues for the practical implementations of the network.

A novel local area network emulation technique on passive optical networks

An optical layer solution for intercommunication between customers in a passive optical network by placing a narrow-band fiber Bragg grating close to the star coupler in the feeder fiber is proposed. The local area network (LAN) emulation technique is experimentally demonstrated with 1.25-Gb/s upstream transmission to the central office and with 155 Mb/s customer data transmission that is multiplexed on a 5-GHz radio frequency carrier. Experimental results show that this technique has the potential to support high data rate LAN traffic while imposing minimal penalty on downstream and upstream transmissions.

Implementation of multiple secure virtual private networks over passive optical networks using electronic CDMA

An optical layer solution for implementing multiple secure virtual private networks (VPNs) over a passive optical network (PON) using electronic code-division multiple access is proposed. The multiple virtual private networking capability is experimentally demonstrated with 40-Mb/s data multiplexed with a 640-Mb/s electronic code that is unique to each of the VPNs in the PON, and the transmission of the electronically coded data is carried out using Fabry-Peacuterot laser diodes. Experimental results show that this technique can potentially support high data rate traffic while imposing minimal penalty resulting from optical beat interference

Upstream Access and Local Area Networking in Passive Optical Networks Using Self-Seeded Reflective Semiconductor Optical Amplifier

A scheme for upstream access and local area networking in passive optical networks (PONs) using a single self-seeded reflective semiconductor optical amplifier (RSOA) placed in customer premises is proposed and experimentally demonstrated. The self-seeding of the RSOA is performed with the use of fiber Bragg gratings placed at the customer premises to obtain two separate wavelength channels for the transmission of upstream access traffic and local area network traffic. The experimental results show that this scheme is capable of supporting high bandwidth data transmission in a PON.

Internetworking VCSEL-Based Hybrid Base Station Towards Simultaneous Wireless and Wired Transport for Converged Access Network

A hybrid base-station (H-BS) scheme that has the potential to establish intercommunications among neighboring access nodes without sending the signals to the edge node to simultaneously transport wireless and wireline services to integrated access nodes is proposed. As the scheme uses vertical-cavity surface-emitting lasers as the light source in the H-BS, it can potentially be realized at low cost without any temperature control.

Popularity-Aware Caching Algorithm for Video-on-Demand Delivery over Broadband Access Networks

Video on Demand (VoD) service is regarded as one of the most promising services over increasingly deployed next generation broadband access networks. The distributed server architecture, in which the popular content is cached at a location closer to the viewer, is a widely used methodology to optimize the transport capacity of VoD delivery. However, due to the dynamic (change with time) nature of movie popularity distribution, identifying the popular content and updating the cache servers accordingly is not straightforward. In this paper, using a novel caching architecture for Passive Optical Networks (PON), we discuss the need for a fast caching algorithm that can respond to time changing movie popularity distribution, and we propose a novel Last-k caching algorithm, which identifies the popular content using the most recent statistics. The proposed algorithm estimates movie popularity using most recent inter-arrival times of movie requests and updates the cache accordingly such that the most popular content at any given time would reside in the cache. Simulations indicate that the proposed algorithm out-performs existing algorithms by effectively responding to the dynamic nature of movie popularity distribution.

10 Gb/s upgrade for high-split and long-reach PON using remote repeater

We report a 10 Gb/s upgrade mechanism of an existing optical access network while enabling high split and long reach transmissions using a remote repeater. The proposed system employs standard transceivers and demonstrates good performance.

LAN emulation on passive optical networks using RF subcarrier multiplexing

This study has proposed and experimentally demonstrates a technique for physical layer LAN emulation on a PON using RF subcarrier multiplexed transmission of LAN data. The results show that this technique is capable of supporting high bandwidth LAN data while having minimal effect on the PON transmissions.

Multiple secure virtual private networks over passive optical networks using electronic CDMA

In this paper, we present the experimental investigation of the use of electronic code division multiple access technique to achieve multiple secure virtual private networks over passive optical network architecture. We also discuss the scalability of this technique using analytical modelling.