A Simple One-System Solution COF-PON for Metro/Access Networks

In this paper, next-generation ultralong reach code division multiplexing (CDM) on fiber (COF) passive optical network (COF-PON) based on CDM (multiplexing carried out in electrical domain) presented here. We describe the system configuration, COF transceiver, key merits such as bidirectional transmission (on the same wavelength with single fiber), extending the reach by coding gain, and offering huge bandwidth to large number of subscribers by overlaying on coarse wavelength division multiplexing (CWDM)/wavelength division multiplexing (WDM). We believe our newly proposed ultralong reach COF-PON will help to drastically reduce the Capex and Opex costs by consolidating metro and access networks into one simple network. We demonstrated initial experimental results over 100-km bidirectional COF-PON overlay on 4lambda-CWDM channels' transmission without the use of an optical amplifier     

Simplified method for passive optical network in-service fibre-fault monitoring based on fibre Bragg gratings

The fibre-fault monitoring is a crucial network element, especially for passive optical networks. In this work is presented and demonstrated experimentally a simplified method for the optical access network monitoring, based on fibre Bragg gratings, deployed near vulnerable network locations. We experimentally demonstrated the use of this technique in a four-branch PON with a maximum span of 60 km, with the FBG monitors placed in several positions along the network. From the experimental results, the proposed method applicability is set for up to 90-km-long networks. Since this method does not require active optical devices, it could be applied in extended reach networks, with reduced implementation costs, which is an advantage to other monitoring methods.     

Low‐Cost,Low‐Power,High‐Capacity 3R OEO‐Type Reach Extender for a Long‐Reach TDMA‐PON

This paper proposes a low‐cost, low‐power, and high‐capacity optical‐electrical‐optical‐type reach extender that can provide 3R frame regeneration and remote management to increase the reach and split ratio with no change to a legacy time division multiple access passive optical network. To provide remote management, the extender gathers information regarding optical transceivers and link status per port and then transmits to a service provider using a simple network management protocol agent. The extender can also apply to an Ethernet passive optical network (E‐PON) or a gigabit‐capable PON (G‐PON) by remote control. In a G‐PON, in particular, it can provide burst mode signal retiming and burst‐to‐continuous mode conversion at the upstream path through a G‐PON transmission convergence frame adaptor. Our proposed reach extender is based on the quad‐port architecture for cost‐effective design and can accommodate both the physical reach of 60 km and the 512 split ratios in a G‐PON and the physical reach of 80 km and the 256 split ratios in an E‐PON.     

A novel approach for physical layer security in future-generation passive optical networks

The ever increasing growth of users and network capacity makes the security of passive optical networks (PON) an issue of great concern. In this paper, we present a novel work to enhance the physical layer security for wavelength division multiplexing orthogonal frequency division multiplexing PON. Elliptic curve with Diffie–Helman key exchange protocol is employed to derive a session key for Advanced Encryption Standard algorithm at optical line terminal and optical network units to provide secure communication. Encryption is applied on partial data of I/Q channel in order to reduce the computational time. Successful transmission of 16-Quadrature Amplitude Modulation encrypted OFDM signals at a distance of 100 km is demonstrated within the limits of peak to average power ratio value.     

12.5 Gbit/s fibre-optic network using all-optical processing

A 12.5 Gbit/s fibre-optic network is implemented with a central mode-locked laser clock, integrated-optic waveguide modulators, optical time-multi/demultiplexing and an optical reservation protocol. The network accommodates 125 stations transmitting at 100 Mbit/s each, using receiver-fixed assignment time-division multiple access.     

SIP mediated services

In this paper we discuss how we can use the session initiation protocol (SIP) to offer advanced services for mobile users over BT’s 21st Century Network (21CN). We provide a brief overview of the advantages of using SIP and describe how SIP can play a vital role in today’s and future heterogeneous networks, such as BT’s 21CN. We demonstrate some advantages of using SIP for handover in these varied networks and we compare it against using other methods for handover, e.g. mobile IP. With the current and anticipated demand for users with multiple devices, we introduce the benefits of using SIP for personal mobility, including the concept of transferring sessions between a user’s many and varied devices. We then consider quality of service issues that present themselves when moving frequently between varied, particularly wireless, networks with varying capabilities and congestion. We describe how we have used codec switching to cope with these adverse conditions, and consider the benefits of shifting the control of this adaptation to the network. This work centres on a custom-built test-bed together with our own real-time SIP-based videoconferencing application with codec switching capability. We present this test-bed, and results based on its use.     

A wireless access network based on WDM-PON for HMIPv6 mobility support

In this paper, an IP-based wireless access network is proposed, which is designed to support the hierarchical MIPv6 standard on the wavelength division multiplexed passive optical network access network in order to provide a fast and seamless handoff support. Two schemes for enhancing the mobility management are included in the proposed network’s infrastructure support. Firstly, the local-link channels between sub-networks are provided to improve the mobility management efficiency for the mobile nodes roaming between neighboring sub-networks. Secondly, the early route optimization scheme has been applied, which optimizes the mobility management process between the corresponding node and the home agent (HA), resulting in reduced bandwidth waste and long end-to-end packet delays, as well as lowering the heavy burden on the HA. The performance of the proposed mobility management scheme has been evaluated in terms of handoff delays, packet losses and transmission costs. The superior performance of the proposed scheme has been verified and compared to other schemes.     

Access points vulnerabilities to DoS attacks in 802.11 networks

We describe possible denial of service attacks to access points in infrastructure wireless networks using the 802.11b protocol. To carry out such attacks, only commodity hardware and software components are required. The experimental results obtained on a large set of different access points show that serious vulnerabilities exist in any device we tested and that a single malicious station can easily hinder any legitimate communication within a basic service set. Francesco Ferreri graduated in Software Engineering in 2004 at Rome University “Tor Vergata”. He then joined CASPUR (Italian Interuniversities Consortium for Supercomputing Applications) where he led research activities involving wireless networks and IPv6 integration. He’s currently employed at NaMeX, Rome’s Internet Exchange Point, as a network and systems engineer. Leonardo Valcamonici graduated in Maths in 1994 at “La Sapienza” University in Rome. After that he joined CASPUR (Italian Interuniversities Consortium for Supercomputing Applications) where, in the beginning, he was involved in research activities in the field of parallel and distributed computing. After that he became a network and security engineer. He is now CASPUR’s Information Systems Security Officer and Network Applications and Services Team Leader.” Massimo Bernaschi graduated in physics in 1987 at “Tor Vergata” University in Rome. After that he joined the IBM European Center for Scientific and Engineering Computing (ECSEC) in Rome. He spent ten years with IBM working in the field of parallel and distributed computing. Currently he is with the Italian National Research Council (CNR) as chief technology officer of the Institute for Computing Applications. Moreover, he is an adjunct professor of Computer Science in “La Sapienza” University in Rome.     

Designing a 21st and 22nd century fibre broadband access network

DSL technology has been incredibly successful at allowing copper telephony wires to deliver broadband services. However, the physics of copper dictate that as speeds increase further it will be necessary to push optical fibre closer to the customer — to the cabinet, and ultimately to the premises. Deploying optical fibre to the mass consumer is well known as representing a significant capital investment and will take many years to deploy. It would be fair to say that putting fibre in the residential access network is a ‘once in a century’ investment. There are many different choices of ‘high fibre’ broadband access systems and as technology develops further, this situation is likely to continue. When operators deploy fibre in the access network, it is therefore vital that they do so in a future-proof manner which can support technologies and architectures yet to come, and allow migration and further evolution.     

ARMS — application of AI and OR methods to resource management

This paper documents work on automating resource management in BT Retail. BT Retail manages BT’s access network and provides telecommunications services to its customers. BT Retail’s field engineers are allocated jobs via an information system known as Work Manager. In order to proactively position the engineers (i.e. resources) so as to service jobs in an optimal manner, resource managers are involved in analysing the profiles of engineers in the light of incoming jobs and ’selecting’ those profiles that will yield best quality of service and reduce operational costs. A profile is a set of attributes that define a resource’s capabilities (i.e. skills), capacity (i.e. availability), and location (i.e. area). Resource planning involves identifying an ‘optimal’ set of resource profiles. Accurate workload forecasting is sine qua non for optimal resource planning. To this end we have developed ARMS, Automated Resource Management System, a suite of components for workload forecasting and resource planning.     

Designing a 21st and 22nd century fibre broadband access network

DSL technology has been incredibly successful at allowing copper telephony wires to deliver broadband services. However, the physics of copper dictates that as speeds increase further it will be necessary to push optical fibre closer to the customer — to the cabinet, and ultimately to the premises. Deploying optical fibre to the mass consumer is well known as representing a significant capital investment and will take many years to deploy. It would be fair to say that putting fibre in the residential access network is a ‘once in a century’ investment. There are many different choices of ‘high fibre’ broadband access systems and as technology develops further, this situation is likely to continue. When operators deploy fibre in the access network, it is therefore vital that they do so in a future-proof manner which can support technologies and architectures yet to come, and allow migration and further evolution.     

Dynamic Bandwidth Allocation Algorithm for Multimedia Services over Ethernet PONs

Ethernet passive optical networks (PONs) are an emerging access network technology that provides a low‐cost method of deploying optical access lines between a carrier's central office and a customer site. In this paper, we propose a new algorithm of dynamic bandwidth allocation for multimedia services over Ethernet PONs. To implement the suggested dynamic bandwidth allocation algorithm, we present control message formats that handle classified bandwidths in a multi‐point control protocol of Ethernet PONs.     

A simple broad-band coherence multiplexed optical access networkand its scalability

This paper proposes a novel and simply configured broad-band optical access network that uses coherence multiplexing (CM) and half-duplex bidirectional transmission. It allows the on-demand use of broad bandwidth on existing fiber-to-the-home (FTTH) access lines. The design of the proposed CM network considers degradation factors in CM systems. This paper introduces two analyses. The first one is a numerical simulation to optimize the tradeoff between available user number and fiber dispersion degradation, and the second estimates acceptable access-line loss in the network. These analyses show that 16 users×100 Mb/s (or 12 users×155 Mb/s) bandwidth Is possible on a standard single-mode fiber access line whose loss and length are under 9 dB and 10 km (and 7 km), respectively. The feasibility and scalability of the proposed network are verified by an experiment in which eight-channel 155-Mb/s half-duplex optical packet transmission is successfully demonstrated on a 7-km standard fiber access line with bit error rates better than 1×10^-9. This study shows that the capacity of existing FTTH access lines that employ star couplers can be significantly enhanced     

Reconfigurable 2.5-Gb/s Baseband and 60-GHz (155-Mb/s) Millimeter-Waveband Radio-Over-Fiber (Interleaving) Access Network

In this paper, we propose a dynamic reconfigurable wavelength division multiplexed (WDM) millimeter-waveband radio-over-fiber (RoF) and baseband access network. We also demonstrate dynamic channel allocation capability of millimeter-waveband optical RoF and baseband signals in WDM access network using a supercontinuum (SC) light source, arrayed-waveguide gratings, and a reconfigurable optical crossconnect switch. The dynamic reconfigurable RoF and baseband network architecture is presented and its features are described. Two 155-Mb/s RoF channels and two 2.5-Gb/s baseband channels are effectively generated, transmitted through 25 km of fiber, switched, and then transmitted again through 2 km of fiber and detected with error-free operation (bit error rate $≪ 10^{-9}$). The proposed architecture allows the RoF and baseband to coexist and is highly scalable, both in terms of channel counts and access point (AP) counts.      

A reconfigurable ethernet/SONET circuit-based metro network architecture

We propose a service concept in which high-speed Ethernet interfaces from end hosts are dynamically cross-connected to equivalent-rate Ethernet-over-SONET (EoS) optical circuits for transport across metro-area networks and/or wide-area networks. We call our service concept reconfigurable Ethernet/SONET circuits to end users (RESCUE). We describe how RESCUE can be used for two applications: dial-up service to Internet service provider routers and file transfers. We propose to deploy RESCUE service as an "add-on" to current Internet access for many reasons. Primary among these is that it allows a metro optical circuit-switched network to be operated at a high utilization, which is important to achieve a cost-effective bandwidth-efficient network. Given that end hosts with access to RESCUE service will have a choice of two paths, the primary Internet path and a secondary RESCUE option, end-host applications will need to make a routing decision. We carry out a quantitative analysis to provide a basis for this routing decision for both dial-up service and file transfers. For example, with the file-transfer application, if call-blocking probability on the optical circuit-switched network is 30% and the packet-loss rate on the transmission control protocol/Internet protocol path is 1%, a circuit setup should be attempted for files 180 KB or larger in low-propagation delay environments.     

Analysis and Simulation of a Plastic Optical Fiber Access Network Based on OCDMA Technology

In this paper a plastic optical fiber (POF) access network based on optical code-division multiple access (OCDMA) technology is proposed. Recently, optical transmission using POF has received much attention due to its low weight, large core diameter, flexibility, and easy installation. Specially, its high bandwidth makes POF a very attractive candidate for a transmission media in an access network based on OCDMA technology. A conventional OCDMA system only allows a finite number of units to transmit and access simultaneously according to the number of channels which is restricted by BER. To resolve this problem a novel protocol is also proposed in this paper. The protocol can efficiently support variable-sized messages, and any new unit can join the network at any time without requiring network initialization. To implement the demonstration, each optical network unit is equipped with a fixed and a tunable optical encoder/decoder. The optical encoder/decoder employing planar holographic optical processors (HOPs) in this system may be of low fabrication cost. The network throughput and average delay using various system parameters has been investigated by numerical analysis and simulation experiments. It is shown that the dynamic control protocol in this POF access network based on OCDMA technology is valid and efficient.     

Seeker: A bandwidth-based association control framework for wireless mesh networks

The rapid deployment of wireless mesh networks across universities and enterprises, and the pervasiveness of mobile devices equipped with Wi-Fi connectivity, has resulted in a scenario wherein end users have the option to choose from a multitude of access points at any given location. Moreover, with the increasing availability of rich online content, there has been a steady increase in mobile Internet traffic. Since the choice of access point that a user associates with will directly impact his performance, it is imperative that there exist an efficient association control mechanism, in order to enhance the end user’s experience. As part of this work, we propose Seeker, a novel framework for association control in wireless networks that utilizes “available bandwidth” as the design metric. The goal of Seeker is to assist the mesh network in making an intelligent decision regarding which access point a client should associate with. As part of our scheme, we implement and evaluate a passive tool to estimate available bandwidth in wireless networks. We then describe how we use this tool to implement our association control scheme, and evaluate it via extensive experiments on an outdoor testbed. Seeker takes into consideration the performance of the mesh backhaul, in addition to the client-to-AP link quality, thereby achieving significant advantages over traditional association control schemes for wireless-LANs.     

Realising the potential of access networks using DSL

This paper provides an overview of digital subscriber line (DSL) technology and describes some of the key technical issues facing BT’s DSL engineering team. The factors which determine the theoretical information-carrying capacity of BT’s access network cables are discussed to give the reader a feel for the potential of the existing access network to deliver broadband services. Transmission on this network will be subject to impairments which will limit the achievable capacity, and there is an urgent need to ensure that all DSL systems are spectrally compatible if the capacity of the network is to be fully realised.     

Architectures and technologies for high-speed optical data networks

Current optical networks are migrating to wavelength division multiplexing (WDM)-based fiber transport between traditional electronic multiplexers/demultiplexers, routers, and switches. Passive optical add-drop WDM networks have emerged but an optical data network that makes full use of the technologies of dynamic optical routing and switching exists only in experimental test-beds. This paper discusses architecture and technology issues for the design of high performance optical data networks with two classes of technologies, WDM and time division multiplexing (TDM). The WDM network architecture presented stresses WDM aware Internet protocol (IP), taking full advantage of optical reconfiguration, optical protection and restoration, traffic grooming to minimize electronics costs, and optical flow-switching for large transactions. Special attention is paid to the access network where innovative approaches to architecture may have a significant cost benefit. In the more distant future, ultrahigh-speed optical TDM networks, operating at single stream data rates of 100 Gb/s, may offer unique advantages over WDM networks. These advantages may include the ability to provide integrated services to high-end users, multiple quality-of-service (QoS) levels, and truly flexible bandwidth-on-demand. The paper gives an overview of an ultrahigh-speed TDM network architecture and describes recent key technology developments such as high-speed sources, switches, buffers, and rate converters