High deployment cost with respect to expected revenue is the main barrier to fiber-to-the-home (FTTH) roll-out in rural areas. This problem, as shown in this paper, is exacerbated by the uncertainty associated with the end-user take-up rate. The randomness associated with subscribers’ service take-up yields considerable fluctuation and escalation in the total cost of deployment. This adverse and varying environment makes it difficult to produce firm business cases and can increase the reluctance of potential investors and incumbent operators to deploy FTTH access networks. In this paper, we develop a holistic framework for examining real-world FTTH deployment scenarios, taking as a case study one of the most rural counties in Ireland. Further, we carry out an in-depth techno-economic analysis identifying the methods more applicable in the rural scenario. We analyze the cost effectiveness of FTTH deployment, also proposing solutions that provide different levels of upfront investment risk, relating it to uncertainty in customers’ take-up rates. For example, we show how a lower take-up rate can be made profitable by adopting a strategy that favors lower upfront costs at the expense of higher connectivity costs.

The physical layout of cables and nodes in many of today’s passive optical networks (s) still dates back to the early days of copper loop installations, with customer to exchange node distances limited to a few kilometers largely by the transmission distance of analogue telephony over the copper pairs. However, modern optical communication technologies can enable much longer transmission distances, and through the use of optical amplification can effectively integrate the access and metro portions of the network into a single all-optical communication system, which is commonly referred to as “Long-reach PON” () or “Amplified PON”. LR-PONs offer several advantages in terms of infrastructure sharing, network node consolidation and core network delayering.

10-gigabit-capable Passive Optical Network XG-PON, one of the latest standards of optical access networks, is regarded as one of the key technologies for future Internet access networks. This paper presents the design and evaluation of our XG-PON module for the ns-3 network simulator. This module is designed and implemented with the aim to provide a standards-compliant, configurable, and extensible module that can simulate XG-PON with reasonable speed and support a wide range of research topics. These include analyzing and improving the performance of XG-PON, studying the interactions between XG-PON and the upper-layer protocols, and investigating its integration with various wireless networks. In this paper, we discuss its design principles, describe the implementation details, and present an extensive evaluation on both functionality and performance.

The convergence of multiple service demands and different user types on a single physical layer can be enabled by dynamically reconfigurable time-division multiplexing (TDM) dense wavelength division multiplexing (DWDM) long-reach passive optical networks (PONs). In this paper we demonstrate two TDM-DWDM PON designs, the first one for densely populated urban areas and the second one better suited for rural deployment. Heterogeneous services and modulation formats, i.e. residential 10G PON channels, business 100G dedicated channel and wireless fronthaul are demonstrated experimentally coexisting on long reach TDM-DWDM PON systems, with at least 100km reach, 1024 users and emulated system load of 40 channels. End-to-end software defined networking (SDN) management of the access and core network elements is also implemented and integrated with the PON physical layer in order to demonstrate two service use cases: a fast protection mechanism with end-to-end service restoration in the case of a primary link failure; and dynamic wavelength allocation (DWA) in response to an increased traffic demand.

Metro-scale TDM-DWDM PONs can enable consolidation of network resources and the convergence of multiple service types on the same infrastructure. Two different SDN enabled metro-scale PON configurations are reported, for densely and sparsely populated areas, supporting 10G PON channels, wireless fronthaul and 100G enterprise services.

The challenging performance targets of future 5G networks will require a radical change in the network design with a much closer interaction between wireless and optical systems. Dynamically reconfigurable time-division multiplexing (TDM) dense wavelength division multiplexing (DWDM) long-reach passive optical networks (PONs) provide a promising platform to enable the convergence of residential broadband, enterprise connectivity and wireless data traffic onto a single network architecture by exploiting the dynamic allocation of DWDM channels. In this paper we describe the architectural choices and the specific technologies that are required by these designs. We also demonstrate the co-existence of heterogeneous services and modulation formats, i.e. residential 10G PON channels, business 100G dedicated channel and wireless fronthaul on long reach TDM-DWDM PON systems. Two different TDM-DWDM PON designs are demonstrated: the first one for densely populated urban areas; and the second one better suited for rural deployment. Two service use cases are also demonstrated by implementing end-to-end software defined networking (SDN) management of the access and core network elements: a fast protection mechanism with end-to-end service restoration in the case of a primary link failure; and dynamic wavelength allocation (DWA) in response to an increased traffic demand.

A dynamically reconfigurable TDM-DWDM PON for converged multi-services at the physical layer (10G, 100G and wireless fronthaul) has been demonstrated for the first time implementing end-to-end SDN management of the access and core network elements.

Long-reach passive optical networks (LR-PONs) prove to be a suitable candidate for future broadband access networks. The longer reach of the feeder fiber in a LR-PON enables us to consolidate a large number of end users. The longer reach also eliminates a degree of electronic processing by eliminating the metro network and connecting the local exchanges (or the central offices) directly to a consolidated metro/core (MC) node. However, longer reach makes the feeder fiber more vulnerable to failures, and therefore, for resiliency purposes, a dual-homed architecture is proposed. For the usual case of 1 + 1 protection, the dual-homed secondary MC node would contain duplicate resources that would take over in the event of the failure of any of the individual working optical line terminals (OLTs) or the entire primary MC node in the case of a catastrophe. In this work we propose an Nl1 protection mechanism to reduce backup OLTs in a resilient dual-homed LR-PON deployment. We model the problem as an integer linear program and solve it for Irish and UK network deployments. Our results show that the percentage of backup OLTs can be reduced by 6 times for Ireland and by 4 times for the UK compared to a 1 + 1 protection deployment scenario.

Maximum balanced load is the load above which mean packet delay and packet loss ratio increase rapidly, queues start to build up and packets start to drop. In this paper, we propose theoretical formulas to analyse the maximum balanced load in Long-Reach Passive Optical Networks (LR-PONs). This is done for two algorithms, the GIANT algorithm and a proposed BwUpdate algorithm. We compare the expressions obtained with simulation studies and find the simulation results match the theory well. We compare the two algorithms as a function of the Assured Bandwidth Restoration Time (ABRT) and find that the BwUpdate algorithm increases the maximum balanced load, for assured bandwidth restoration times longer than 3.75 milliseconds.

Hierarchical metro and core network designs, which dominate today's networks, become increasingly cost-inefficient as traffic grows. In this paper we show that flat architectures are lower cost and we propose a migration strategy that ensures cost-efficiency throughout the migration process.

Dynamically reconfigurable time-division multiplexing (TDM) dense wavelength division multiplexing (DWDM) long-reach passive optical networks (PONs) can support the reduction of nodes and network interfaces by enabling a fully meshed flat optical core. In this paper, we demonstrate the flexibility of the TDM-DWDM PON architecture, which can enable the convergence of multiple service types on a single physical layer. Heterogeneous services and modulation formats, i.e., residential 10G PON channels, business 100G dedicated channel, and wireless fronthaul, are demonstrated co-existing on the same long reach TDM-DWDM PON system, with up to 100 km reach, 512 users, and emulated system load of 40 channels, employing amplifier nodes with either erbium-doped fiber amplifiers or semiconductor optical amplifiers. For the first time, end-to-end software-defined networking management of the access and core network elements is also implemented and integrated with the PON physical layer in order to demonstrate two service use cases: a fast protection mechanism with end-to-end service restoration in the case of a primary link failure; and dynamic wavelength allocation in response to an increased traffic demand.

Seeking reduction of capital and operational costs on next-generation fiber networks is the holy grail of network planning and deployment for all operators worldwide. In particular, efficient deployment strategies of next-generation fiber access networks is of paramount importance to enable wide-scale ubiquitous deployment of high-speed broadband services. Exploiting the large capacity of fiber networks to support heterogeneous services from residential and business users is a promising strategy toward this goal. Long-reach passive optical networks (LR-PON) is one such strategy that also adopts greater sharing of active and passive components, together with consolidation of central offices, to reduce capital and operational expenditures. However, due to its long reach and large split ratio, protection mechanisms become a major consideration when designing an LR-PON, as a single feeder cable cut could disrupt services for several thousand users. In this paper, we demonstrate fast restoration of LR-PON services using a dual-homed shared optical line terminal (OLT) protection mechanism. Our end-to-end testbed connects our optical access broadband laboratory operating on custom built LR-PON ONU and OLT field programmable gate array prototypes with a Europe-wide testbed core network. We use a software-defined network control plane to manage the dual-homed N:M protection switching and traffic reroute in the core and achieve access protection and end-to-end services restoration times of 40 and 80 ms, respectively.

Long reach-passive optical networks (LR-PON) are being proposed as a means of enabling ubiquitous fiber-to-the-home (FTTH) by massive sharing of network resources and therefore reducing per customer costs to affordable levels. In this paper, we analyze the chain solutions for LR-PON deployment in urban and rural areas at 100-Gb/s point-to-point transmission using dual polarization-quaternary phase shift-keying (DP-QPSK) modulation. The numerical analysis shows that with appropriate finite impulse response (FIR) filter designs, 100-Gb/s transmission can be achieved with at least 512 way split and up to 160 km total distance, which is sufficient for many of the optical paths in a practical situation, for point-to-point link from one LR-PON to another LR-PON through the optical switch at the metro nodes and across a core light path through the core network without regeneration.

Future network operation will be influenced by business and ownership models and the regulatory environment as future superfast and flexible broadband networks emerge. This paper discusses the issues affecting operators and network operations as network evolution progresses.

We demonstrate fast restoration of PON services with a dual-homed, shared-OLT protection mechanism. Using the SDN-controlled pan-European GEANT core network, we demonstrate PON protection and end-to-end service restoration times within 40ms and 155ms respectively.

Tackling the digital divide has become one of the main goals of many governments around the world, and a main target for the European Commission. Fibre-to-the-premises (FTTP) is the only access technology that has the potential to totally eliminate the digital divide since, within access distances, fibre capacity can be considered distance independent. In practice, however the higher cost means that many rural areas might not be served by FTTP services, further widening the capacity gap between rural and urban access. However, while fibre roll out is certainly less cost-effective in rural than urban areas, a proper deployment strategy that minimises cable installation costs can increase the network profitability and thus the rural FTTP coverage. In this paper, we propose a novel agglomerative clustering algorithm. The algorithm together with ILP and heuristic models, attempt to minimise the total fibre cable required to connect sparse rural users to a drop PON splitter located up to several kilometres away from the user. Our results show that proper deployment strategies can increase the use of large last-stage splitter, thus increasing sharing of fibre among users, while still minimising the overall cable length. In addition, we show that our heuristic is able to obtain similar results as the ILP (i.e. within an 8% margin), but can reduce the computation time by about 6 times, for the scenarios we have considered.

Fiber to the premises has promised to increase the capacity in telecommunications access networks for well over 30 years. While it is widely recognized that optical-fiber-based access networks will be a necessity in the short to medium-term future, its large upfront cost and regulatory issues are pushing many operators to further postpone its deployment, while installing intermediate unambitious solutions such as fiber to the cabinet. Such high investment cost of both network access and core capacity upgrade often derives from poor planning strategies that do not consider the necessity to adequately modify the network architecture to fully exploit the cost benefit that a fiber-centric solution can bring. DISCUS is a European Framework 7 Integrated Project that, building on optical-centric solutions such as long-reach passive optical access and flat optical core, aims to deliver a cost-effective architecture for ubiquitous broadband services. DISCUS analyzes, designs, and demonstrates end-to-end architectures and technologies capable of saving cost and energy by reducing the number of electronic terminations in the network and sharing the deployment costs among a larger number of users compared to current fiber access systems. This article describes the network architecture and the supporting technologies behind DISCUS, giving an overview of the concepts and methodologies that will be used to deliver our end-to-end network solution.

Network protection is a key feature of communications systems to ensure minimal packet loss when failure occurs in the data path. Segment protection is typically used to reroute data around a failed link, using secondary backup paths. We propose a novel solution to this problem, proposing an Independent Transient Plane (ITP) design that reduces the complexity of the path configuration process and the usage of resources in the routing elements, compared to current solutions. This work complements our previous studies, by reporting the results of an international testbed implementation over a pan-European network, showing protection times below 20 ms.