High-Level Network Overview
Gigabit broadband is a crucial infrastructure, empowering citizens and businesses in underserved areas with high-speed Internet access and fostering prosperity in today’s interconnected global economy. Simultaneously, it establishes a robust communications foundation for utilities, supporting a reliable and efficient grid. Additionally, it facilitates the integration of distributed renewable energy resources, contributing to carbon reduction objectives.
To enhance the viability of the business case, utilities are exploring various options to expedite fiber-to-the-home (FTTH) deployments, share investments and risks, and boost service adoption. An increasingly favored approach involves leveraging open access networks to align with their business goals.
Broadband networks comprise three fundamental levels, and a power utility may require any combination of these:
Access Network
Links residences and businesses to access nodes, where initial traffic aggregation occurs.
Aggregation Network
This network combines traffic from multiple local access nodes and extends it further into the network (regional, metro, or backhaul network).
Core Network
Connects traffic from different areas, municipalities, or regions (backbone network).
For smaller areas, a basic broadband network may consist of a few access nodes and a software platform managing services for each user. However, open-access broadband networks for larger regions typically encompass aggregation and core networks, providing more intricate functionalities. Decisions are influenced by factors such as network size, coverage area, and the connection point with the national network.
The aggregation network comprises aggregation access nodes, while the core network includes service routers and transmission switches. Service routers play a pivotal role in forwarding data packets, ensuring the right quality of service for each user based on service level agreements. They may also function as full broadband network gateways (or edge routers) for retail-type services, acting as a hand-off between networks.
Aggregation and core networks can be structured in various topologies:
Tree
Aggregates traffic hierarchically, cost-effective but less robust.
Ring
Establishes a ring connection for added security in case of faults, albeit more expensive.
Meshed
Connects each network element to several others, offering the highest level of robustness but at increased cost and complexity.
Mixed
This type of network Combines tree, ring, and meshed structures, tailoring it to specific needs (e.g., tree for residential, ring for businesses, meshed for critical establishments like hospitals and data centers).
The Access Network
The access network is the gateway for subscribers to connect to the broader network through an access node. Various fixed access technologies are available for this purpose, depending on the physical medium to link subscribers—such as copper, optical fiber, or coaxial cable. This discussion focuses on optical fiber, particularly in the context of a Fiber-to-the-Home (FTTH) network, which is a prevalent choice for open-access broadband deployments.
The FTTH access network may interconnect the following entities:
- Residential users
- Businesses, schools, universities, hospitals, and other organizations
- Mobile network base stations and antennas
- Public security structures encompassing sensors, surveillance cameras, and alarms.
Within an FTTH access network, two end-points are crucial, each serving distinct functions:
Subscriber’s Premises
This end-point features an Optical Network Termination (ONT) device at the subscriber’s premises. The ONT connects to various home devices, including PCs, TVs, set-top boxes, phones, and Wi-Fi devices like tablets and smartphones. Functioning as a demarcation point, the ONT delineates the home and operator networks.
Access Node (OLT)
The second end-point is the access node, the Optical Line Termination (OLT) point. Typically located in a central office or a field cabinet, the access node aggregates connections from multiple users, linking them to the aggregation or core network.
The outside plant comprises passive components, including:
- Optical fiber cables
- Splitters facilitating signal sharing from the access node among several users
- Duct or micro-duct systems housing the fiber-optic cable
- Fiber splice enclosures
- Drop cables, installed when a subscriber subscribes to the service
- Network access points or terminal points to which drop cables connect
- Optical distribution frames organize fiber-optic cable connections.
The distribution network (feeder plant) within the outside plant extends from the access node to the main fiber connection, covering several kilometers or miles.
The connection to homes and businesses, known as the “last mile,” can adopt two basic topologies:
Point-to-Multipoint (P2MP)
The access node links multiple users over the same shared medium using a single transmitter. This approach is widely employed in wireless (e.g., 3G and 4G networks) and wired communications (PON and cable networks), with a splitter dividing the signal from the fiber feeder into output branches.
Point-to-Point (P2P)
The access node connects multiple users, each with a dedicated connection utilizing a corresponding number of transmitters. This method finds application in radio communications, copper-based broadband technologies (xDSL), and Ethernet point-to-point setups.
Network Planning
Investing significantly in FTTH infrastructure demands meticulous planning to mitigate costs and risks. Successful business cases hinge on thorough planning throughout the development process, considering economic, legal, political, and business factors that influence the deployment and operation of a broadband services network. In this context, we’ll delve into the technological considerations.
When modeling network economics, it is crucial to consider numerous parameters and identify the most sensitive ones pivotal to decision-making. Network planning involves distinct phases:
Strategic Network Planning
- Outputs: Business case and major strategic decisions.
- Examples: Choice of technology and type of outside plant to deploy.
High-Level Network Planning
- Outputs: Lowest-cost network design within strategic planning boundaries.
- Includes: Construction strategy, redundancy paths, demarcation points, preliminary bill of materials, points of presence (POP), and distribution points.
Detailed Network Planning
- Provides tailor-made network drawings and documentation for build-out and operations.
- Requires decisions based on a clear vision of services offered, network operation, deployment and operation costs (CAPEX/OPEX), accurate geographical and local data, and technical details of the network’s capabilities.
- Collecting comprehensive data is crucial for early, informed decision-making.
- Corrective decisions may be needed as the project progresses and new information arises.
For utilities venturing into the FTTH open-access network, relying on industry experts and software-based planning tools is essential. These tools help process data, create scenarios with different assumptions, compare results, select the optimal proposal, and generate detailed build plan documentation. This approach ensures a well-informed and adaptive strategy throughout the FTTH network implementation.
Technology Choices (H3)
A pivotal decision in broadband projects revolves around choosing between Ethernet Point-to-Point (P2P) and Passive Optical Network (PON) technology. While both technologies offer advantages and have found applications in broadband networks, PON has emerged as the dominant choice in contemporary FTTH deployments.
In a PON network, the outside plant demonstrates significant economic advantages. It operates passively, eliminating the need for power supplies, batteries, electronic maintenance, or upgrades. Technological advancements, such as spanning fiber, enclosures, fiber management cabinets, splitters, fusion splicing, and active equipment, have optimized PON. These enhancements enable the density and flexibility required for large-scale deployments. As a result, PON stands out as the fastest-growing access technology in today’s landscape.
It’s worth noting that PON encompasses various types, each offering distinct capabilities and features. This diversity allows for flexibility in addressing specific requirements and scenarios in FTTH deployments.
GPON (Gigabit Passive Optical Network) stands out as the global technology of choice for delivering high-speed broadband services, with successful implementations in open-access broadband projects like EPB Chattanooga, Bolt Fiber Optic Services, and LUS Fiber. Major service providers such as AT&T and Verizon also leverage GPON technology.
High Speed
GPON transmits data from the access node at a swift speed of 2.5 Gbps.
Shared Technology
GPON operates as a shared technology, using a single fiber-optic cable in the distribution network. A passive splitter near users fans out multiple fibers, sharing bandwidth among users (typically 32 users).
Cost-Efficient and Simplified
Fewer active components are required, resulting in lower costs, reduced complexity, lower power consumption, less floor space in the central office, and simplified management compared to active technologies.
Long Reach and Coverage
GPON has a long reach and can cover large areas, connecting hundreds of users from a single access node. This is particularly beneficial in lightly populated areas, reducing deployment costs.
Dynamic Bandwidth Allocation
Allows dynamic bandwidth allocation based on usage demand, ensuring optimal broadband speeds for users. For example, increased speed during large file or movie downloads enhances user experience.
Future-Ready
Easily upgradeable to next-generation technologies without altering the fiber plant. Introducing TWDM-PON electronics, for instance, can increase network capacity by 20 using the same fiber infrastructure and passive components.
In contrast, Ethernet Point-to-Point (P2P) technology provides a direct and dedicated fiber connection from the Ethernet switch to a single household or business. While most Ethernet P2P networks deliver 1 Gbps to each user (upgradeable to 10 Gbps), they come with higher operational costs than GPON. Dedicated connections result in more fibers, larger ducts, increased maintenance, more equipment in the central office, and longer repair times in case of cable cuts or other issues. The Ethernet switch may be located in the central office or deeper in the network, adding complexity and operational costs.
Network Capacity
In the face of escalating traffic volumes, network providers must make informed decisions regarding network capacity. Failure to accurately assess capacity requirements can result in subpar network performance and customer dissatisfaction and necessitate additional investment cycles. Conversely, overestimation may lead to unnecessary overinvestment, tying up capital that could be allocated elsewhere.
To determine network capacity, it is imperative to consider both current and future user demands and identify potential bottlenecks in the network. Nokia offers a distinctive bandwidth-modeling tool, leveraging global experience to forecast aggregated bandwidth demand in fixed networks. This tool analyzes user traffic patterns, consumer behavior, and service evolutions, aiding network providers in making well-informed decisions.
Key Insights on Bandwidth Demand Trends:
Types of User Traffic
Sustained and burst traffic are two distinct types, each influencing network capacity differently.
Dominance of Video
Video, encompassing pay TV, video on demand, and over-the-top internet video (e.g., YouTube, Netflix), constitutes the most significant component of sustained bandwidth demand.
Contributors to Bursts
Speed tests and file transfers primarily contribute to traffic bursts, creating peak bandwidth demand. Calculations must account for both sustained and burst traffic.
Asymmetrical Traffic Patterns
While the demand for upstream capacity is rising, overall traffic patterns are becoming increasingly asymmetrical, with greater bandwidth required for downstream traffic.
Access Network Performance Sensitivity Points
Last-Mile Connection
The last-mile connection to users, influenced by access medium (e.g., copper or fiber) and transmission technology (e.g., xDSL or GPON), determines available bandwidth. Fiber, with virtually unlimited potential, requires careful consideration in point-to-multipoint networks like GPON, where bandwidth is dynamically shared.
Access Node Capacity
The access node, aggregating traffic from multiple users, necessitates sufficient switching capacity. This includes the capacity of the connection point, internal links between hardware components, and the processing capacity of the controller unit.
Uplink Capacity
Ensuring adequate uplink capacity from the access node to the aggregation or core network is crucial. The access node must provide an efficient upgrade path to accommodate additional capacity.
Future-Readiness and Total Cost of Ownership (TCO)
Given the growing demand for high-bandwidth services, network operators should invest in high-capacity access nodes to make their networks future-ready. This strategic approach eliminates the need for frequent investment cycles in the short- or mid-term, ultimately reducing the total cost of ownership.
Service Delivery Model
Utility broadband services can be deployed through two distinct models: the Retail Service Delivery Model and the Open Access/Open Service Model.
Retail Service Delivery Model
In the Retail Service Delivery Model, the utility acts as both the network operator and service provider.
This model is preferable when the infrastructure network provider (utility):
- Desires full control over services delivered.
- Intends to operate both the network and services.
- Possesses staff and experience in running networks and providing services, such as municipal utilities.
In this model, the utility owns the relationship with subscribers, defining, promoting, delivering services, and billing subscribers. It involves direct competition with other service providers in the area.
Open Service Delivery Model
The Open Service Delivery Model is chosen when the infrastructure network provider (utility):
- Lacks available or experienced staff in network operation.
- Prefers to outsource network operation.
- Does not want to compete or is legally restricted from competing against service providers.
- Seeks the option of having multiple service providers as tenants.
Benefits of Open Access Service Delivery
- Diverse Service Providers: Supports various complementary or competing service providers.
- Competition and Choice: Multiple service providers can use the same network asset and compete for subscribers.
- Operational Efficiency: Qualified network operators handle network maintenance and management, relieving utility administrators of operational burdens.
- User Freedom: Users are not bound by specific contracts and can freely choose among all service offerings.
For the success of the Open Access business model, the network architecture must facilitate connectivity for a variety of service providers, ensuring transparent and impartial service delivery, performance guarantees, and deployment flexibility, all at a low Total Cost of Ownership (TCO). Innovations like Software Defined Access Networks (SDAN) contribute to achieving these goals more efficiently.
SDAN
Network Functions Virtualization (NFV)
NFV conceptualizes the virtualization and centralization of network node functions in the cloud.
Software Defined Network (SDN)
As an approach in network management, SDN delivers automated and intelligent control over nodes and other assets within the network.
Defining network behavior from the cloud enables operators to access data throughout the network, facilitating the execution of algorithms and analytics. This results in a network that is not only programmable but also automated. Moreover, it fosters the establishment of open interfaces and standards, enabling seamless integration across diverse technologies, systems, and vendor environments.
The hardware and software disaggregation in independent modules provides operators with expanded engineering options to evolve the access network. This versatility allows them to respond swiftly to changing demands or usage trends, elevate network performance, and minimize service impact during software upgrades or equipment replacements.
Outside Plant Deployment Options
The decision on deployment techniques for network infrastructure is crucial, as it can account for up to 70% of the total network cost. Continuous innovations in techniques and materials are reducing deployment costs, offering network providers increased flexibility. Multiple techniques can be employed based on factors such as network size, available infrastructure, synergies with other projects, and specific circumstances.
In network planning, leveraging different right-of-way access points is vital. Options like deploying aerial cables or utilizing water, gas, or sewage infrastructure can yield substantial cost savings and enhance the overall business case. Compliance with regulations and initiating the permission process in a timely manner are essential considerations.
Various duct infrastructures, ranging from large to micro and flexible to rigid, are available for underground cabling. This allows for diverse installation tactics and supports network growth. Micro-trenching offers a shallow underground route that is resistant to damage but at a higher cost, while full trenching is a more secure but costlier method.
Aerial cabling, using poles and existing infrastructure, is more cost-effective than underground cabling, significantly reducing deployment costs. Although fast and easy to install, aerial cabling is more sensitive to environmental damage. Considerations for aerial cabling include:
- Existing pole infrastructure load capacity.
- Cabling type.
- Hardware for cable fixation.
- Protection against vandalism.
The choice of deployment technique requires careful evaluation of cost, regulations, and infrastructure considerations, with a strategic mix of techniques being a viable approach for optimal results.
Deployment Inside Residential/Business Properties
FTTH networks drive the gigabit revolution, offering endless possibilities for premium consumer and business experiences across devices. The increasing complexity of home networks, driven by diverse devices and gigabit speed demands, presents challenges for users and service providers.
Equipment inside the home in an FTTH network includes the ONT and the Residential Gateway (RGW). The ONT terminates the fiber connection, while the RGW provides in-home network connectivity and services support. Integrating home network.
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