Nishaanthan Nadarajah

We review recent progress on all-optical virtualprivate-network (VPN) schemes in passive optical networks (PONs). PON is a promising candidate in future access areas to provide broadband services with low cost. With all-optical virtual private network (VPN) function, PON can support efficient internetworking among end users with dedicated optical channels, thus enabling guaranteed bandwidth and enhanced security at the physical layer. Here, we discuss and compare existing schemes of all-optical VPNs in time-division-multiplexed (TDM) PONs, and also recently proposed schemes for deployment in wavelength-division-multiplexed (WDM) PONs and two-stage TDM/WDM PONs. OLT

ABSTRACT 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.

Optical fibre communication is very much preferred for the communication of signals over bandwidth of a gigabits per second over distances more than hundreds of kilometres. For a long period of time optical fibre communication has been about how to provide higher bandwidths with reduced cost per bit transmitted. However, this trend has changed from optical transmission to optical networking. By exploiting the wavelength division multiplexing (WDM) technology, optical networks have expanded from backbone networks to metropolitan and access networks to deliver high bandwidth services to the users in a seamless fashion with reduced cost. The ultimate evolution of the optical access network involves fibre-to-the-home (FTTH) technologies, which can potentially offer every kind of information and communication related services. Out of all FTTH technologies, the passive optical network (PON) can potentially offer the most cost-effective solution as the optical network is shared between a n...

ABSTRACT We propose and experimentally demonstrate an in-service surveillance scheme for passive optical networks using electronic code division multiple access. We show that this technique can be used to monitor users with minimal penalty for upstream-data.

ABSTRACT We propose and experimentally demonstrate the feasibility of a control packet signaling technique using electronic code division multiple access for a wavelength division multiplexing packet-based network, whereby each wavelength channel is assigned a unique electronic code based label on a radio frequency subcarrier. Such a technique allows each wavelength channel to be electronically identified without requiring the use of a WDM demultiplexer. We experimentally demonstrate this technique with two wavelength channels each with 1.25 Gb/s baseband payload data and 10 Mb/s header coded onto an electronic code at 160 Mb/s. A performance study of the electronic code division multiple access based control signaling scheme in a wavelength division multiplexed packet-based access network is also performed in terms of the required power budget to monitor the electronic code division multiple access control signals in the presence of several sources of noise for error-free transmission of both payload data and electronic code division multiple access based control signals. It is shown that the modulation depth of each signal impacts the amount of required optical tap power. As the modulation depth of the electronic code division multiple access based control signal is increased, the required optical tap power is reduced. However, this increases the bit-error-rate for the payload data. Therefore, there lies a maximum and a minimum of the required tap optical power for the successful recovery of both signals. The lower bound of this range is usually determined by the successful recovery of electronic code division multiple access based control signal while the upper bound is determined by the successful recovery of payload data. The required optical tap power is analyzed for different transmission bit rates of the payload data for various receiver architecture scenarios without an optical amplifier at the receiver. The scalability analyses were repeated with an optical amplifier placed in the receiver terminal of the network. The resulting optical tap power that is required for the successful monitoring of the electronic code division multiple access based control signals are compared with that of the case without the amplifier.

We propose and experimentally verify a scheme for fast automatic protection switching and customer networking in an Ethernet passive optical network by redirecting the upstream signals back to the customers using a secondary distribution fibre.

ABSTRACT We have proposed and experimentally demonstrated a scheme for upstream transmission and LAN emulation in PONs using a single wavelength-seeded RSOA at the ONU. The upstream and LAN wavelength channels for wavelength seeding were delivered to all ONUs from the CO, thereby eliminated optical sources at the ONU. The experimental results show that all signals can be recovered with minimal penalty

ABSTRACT A hybrid base station scheme that has the potential to establish inter-communications 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. This scheme uses a single reflective semiconductor optical amplifier at the hybrid base station for both the upstream transmission and the local networking. The reflective semiconductor optical amplifier is self-seeded with the use of narrowband fiber Bragg gratings and therefore it does not require external seeding sources and hence provides wavelength switchable capabilities.

ABSTRACT We propose a scheme for a signalling mechanism for routers and/or switches in an optical network while enabling monitoring of chromatic dispersion using an inband RF subcarrier channel. We experimentally demonstrate the proposed scheme with a RF subcarrier at 7 GHz transmitting 3 Mb/s data over 52.8 km SMF along with a 10 Gb/s baseband data channel with a power penalty of less than 0.5 dB.

ABSTRACT A novel scheme for upstream transmissions and local area network emulation amongst customers in passive optical networks by current-tuning a vertical cavity surface emitting laser placed at the customer premises is proposed and experimentally demonstrated.

ABSTRACT We propose and experimentally demonstrate a scheme for upstream transmissions in passive optical networks using electronic code division multiple access. We theoretically show the scalability of the scheme in terms of number of simultaneously supported customer units and bandwidth in the presence of optical beat interference.

ABSTRACT A performance study of electronic code division multiple access (E-CDMA) based control signaling scheme is presented in terms of power budget for error-free recovery of payload and E-CDMA signals in the presence of several noise sources.

ABSTRACT 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.

ABSTRACT A first-order polarisation mode dispersion (differential group delay (DGD)) monitoring technique using a low-speed detector for 40 Gb/s return to zero data transmission is proposed and experimentally demonstrated. The monitoring technique is based on adding an additional optical carrier which is frequency-shifted with respect to the data carrier at an orthogonal polarisation state. The added carrier beats with the data clock tones generating new RF tones at the photodetector output whose power depends on a sinusoidal function. By properly setting the frequency shift between optical carriers, a low-frequency radio-frequency (RF) tone is generated and used for DGD monitoring of high-speed data, providing a cost-effective solution, high resolution and wide monitoring range compared to traditional RF-tone-based DGD monitoring techniques. Experimental results show successful DGD monitoring from 0 to 25 ps with an RF-tone dynamic range of 18 dB. Insensitivity of the proposed technique to chromatic dispersion and optical signal-to-noise ratio is also demonstrated.

ABSTRACT An optical layer solution for implementing multiple virtual private networking capabilities over a passive optical network using subcarrier multiplexed (SCM) transmission is proposed and experimentally demonstrated with 60-Mb/s data multiplexed with two radio-frequency subcarriers. The transmission of the SCM data is carried out using Fabry-Perot laser diodes. Experimental results and theoretical analysis show that our technique can potentially support high data rate traffic from a large number of simultaneous virtual private networks with minimal penalty resulting from optical beat interference

ABSTRACT We propose and experimentally verify a scheme for fast automatic protection switching and customer networking in an Ethernet passive optical network by redirecting the upstream signals back to the customers using a secondary distribution fibre. (2 pages)

A source-free base station scheme with the capability to provide simultaneous access to wireless and wireline services is proposed. The proposed scheme can establish inter-communications among neighboring base stations without sending the signals to the central office.

We report a low-cost and bandwidth-efficient scheme for delivering video services to customers over a repeater-based optical access network. Video channels are locally regenerated and delivered on a single wavelength channel together with downstream data.

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.