Therefore, the network infrastructure must adapt to these growing demands. In the external plant of the network, this means replacing copper technology with fiber optics. Since fiber optics are already very close to the end customer in many cities, it is possible to connect buildings directly using FTTH (Fiber to the Home) or FTTB (Fiber to the Building) solutions.
Residential and commercial buildings (Multi-Dwelling Units, or MDUs) play a key role. Due to the high density of end customers, the investment per customer required by telecommunications companies becomes cost-effective. However, connecting MDUs to the network requires a precise understanding of local conditions. A wide variety of different communication infrastructures, developed over time, exist in different EU countries. Furthermore, numerous regulations and conditions must be met.
Connection strategies also differ depending on whether the goal is to upgrade existing infrastructure or connect a new area. To address these diverse connection conditions, in addition to specific projects, solutions that can be flexibly adapted are required.
While the US prefers the installation of connectors, especially in the form of Plug & Play modular units in P2MP (Point-to-Multi-Point) fiber optic networks, European networks have thus far been dominated by P2P (Point-to-Point) networks, often with permanent splice structures. Debating which of the two alternatives is better is pointless when such a wide range of constraints must be addressed. Rather, the two technologies should complement each other in a comprehensive solution that can be individually tailored to each project with maximum flexibility.
MDUs, vital for network operators offering FTTH.
In Europe, the FTTH (Fiber to the Home) market is very different from its US counterpart. Typically, in the US, large, homogeneous residential developments, business parks, and industrial zones predominate, many of which are greenfield or brownfield projects—that is, newly developed or redeveloped areas. These areas, usually created uniformly, offer ample space and facilitate the planning of the connection infrastructure.
In contrast, Europe is characterized by heterogeneous infrastructure resulting from historical growth and irregular street layouts. In densely populated regions, most buildings consist of multi-dwelling units (MDUs) ranging from three to eight stories. In addition to residential units, these buildings often also house commercial spaces (mixed-use). Nearby are also homes, service providers, and small and medium-sized enterprises.
MDUs are of great importance to FTTH strategies. While in the US it is estimated that almost a third of end customers are located in MDUs (Main Transit Units), in the EU almost 70 percent of the population lives and works in cities, mostly in MDUs. Broadband service providers can serve many customers in a small area, but fiber optic connectivity requires a comprehensive approach that encompasses all possible connection conditions.
The access area
: From the headend (Central Office, CO), buildings are connected either directly via P2P fiber networks or via P2MP fiber distributions using splitters located in the field or within the building.
The fiber optic network rollout typically follows the existing copper infrastructure. However, along the route to the MDU (Maintenance Unit), the problem often arises that existing conduits are already heavily loaded, and water and gas supply pipes usually run beneath sidewalks. Laying additional cable for the FTTH infrastructure is quite difficult and frequently requires costly earthmoving work. If empty conduits are available, the optical fiber can be blown into them over several hundred meters (blown fiber technique). We do not typically consider external cabling to the building, at least in our countries, although it is common practice in others.
Distribution Design:
The way fiber optic lines are laid, terminated, and installed directly influences the performance, lifespan, and cost-effectiveness of a network. Therefore, cable management is of vital importance. The network's flexibility to adapt to future demand also depends on it.
Widespread use of connectors and Plug & Play solutions allows for flexible network setup and expansion, and facilitates access for testing. This allows network participants in a given area to connect gradually.
In many cases, permanent connections via splices are unavoidable. For example, if space limitations prevent the use of junction boxes with additional pathways, or if the available budget for attenuation requires strict cost-cutting on attenuators.
Different Building Types
: Typical MDUs consist of three to eight floors with two to four units each. The ground floor is often used for commercial purposes, such as shops, restaurants, or banks. The units on the remaining floors are used for residential or professional purposes, such as medical practices, offices, or law firms.
These multi-unit buildings present a significant challenge for fiber optic cabling and require individual planning to ensure the FTTH network can be scaled efficiently and reliably on each floor. It is also important to determine whether each unit is owned or rented. In these types of buildings, it can be particularly advantageous for network operators to upgrade from FTTB to FTTH and supply each unit directly with fiber optic cable. If FTTB is continued—that is, if fiber optic cable is only brought to the building—the operator must connect to the building's existing infrastructure, primarily copper, ideally without interruption. This connection is technically complex and involves numerous legal considerations. Direct fiber optic delivery to each unit depends on the infrastructure available for laying the cables, as well as property ownership. Complex negotiations may be necessary in these cases.
Some of these buildings have vertical and horizontal cable ducts that already carry coaxial cables for cable television networks or other utility lines. Fiber optic cables can also be run through these ducts; due to their physical properties, these fiber optic cables can be deployed alongside power supply cables. If dedicated fiber optic ducts are not available, or are unsuitable, network designers face a significant challenge: cabling to the different floors must be carried out without incurring exorbitant costs and without the installation being visually unsightly. Disused chimney flues are often also used. Depending on the building's condition, in recently renovated buildings, subsequent fiber optic cabling may not be possible for an extended period. Network operators should try to discuss the appropriate options and measures with MDU owners as soon as possible.
Housing complexes are also typical MDUs. They usually have two to four stories and several apartments per floor. In older buildings, the future installation of fiber optic cables was often not planned for, resulting in a lack of the necessary infrastructure. This presents a significant challenge for network designers, as previously mentioned. Due to the irregular structure, connecting each building is often difficult. Earthworks are frequently required in the exterior areas as well. These installations are complex and costly.
Connecting MDUs to Fiber Optic Networks:
Among the biggest challenges in connecting buildings are project development planning and logistics. Good project planning helps minimize logistical work and execution time, reducing costs. When planning an MDU connection, always keep the following questions in mind:
1. Type and age: Is the building a national monument? If so, special regulations will most likely apply.
2. Condition of the building: Has it recently been renovated, or is renovation still pending?
3. Use: Is it a residential complex, an office/commercial building, or a mixed-use building?
4. Ownership: Does the building consist of owner-occupied or rented units?
5. Access: Where is the cable connection point? Are there existing conduits? Is there access for maintenance?
6. Infrastructure: Does the building only have copper wiring? How old are the copper lines installed in the building? Are there existing cable conduits that can be reused? Who owns the lines and conduits?
7. Competitors: Are there other active service providers in the building? For example, empty conduits from a cable television provider could potentially be used to run fiber optic cable to the apartments/offices.
Technicians can only enter the property after scheduling an appointment. Furthermore, it is essential to clarify the property's status and the responsibilities within the property before installation. To minimize the number of permits required, additional access points should primarily be located in common areas, such as the entrance to a shared basement. This ensures easy access for any future work.
FTTH connection typically occurs in two stages. First, the fiber optic cables from outside the building are terminated in the basement. There, the transmission medium is switched to the existing copper wiring. Customer connection via FTTB/FTTH.
The direct connection of end customers to the fiber optic network (i.e., the actual FTTH connection) often occurs in a second, subsequent stage. This requires addressing other issues. Unlike in the US, in Europe, for example, it is not common practice to run cables or lines overhead or in conduits on building walls. Therefore, technicians must utilize vertical shafts, such as disused chimney flues, to reach end users on different floors. In this case, fire safety and architectural regulations must also be considered.
In building cabling, the type of fiber optic cable and its quality are crucial factors. Fiber optics are not as easy to install as copper cable: they are sensitive to mechanical stress, which increases signal attenuation. Therefore, recent advancements (such as robust single-mode fiber cables with a reduced bending radius) can play a key role in this situation.
Connectorization or splicing?
This question is difficult to answer definitively. Typically, both connection systems are combined. Due to their flexibility, connectors are often used in P2P networks at the headend (Central Office/CO) and at the customer end. In P2MP networks, connectors are also used to quickly and flexibly insert and switch services in outside plant (OSP) areas, e.g., in distribution frames with Plug & Play splitters. The most suitable procedure also depends on whether an existing infrastructure exists and how colocation (access to other operators' networks) is addressed. To develop the network cost-effectively in a wide range of possible scenarios, the best approach is to use flexible and easily adaptable solutions. Therefore, a suitable combination of pre-configured standard components
and customized solutions (splicing and
quick-connects) is crucial during planning and installation.
ADC Krone is the right partner.
ADC Krone offers a comprehensive range of products for fiber optic network infrastructure, covering all the needs of an FTTH network, from the headend and outside network to the subscriber connection.
Thanks to its long-standing global market presence, ADC Krone has a deep understanding of the conditions in each country, both in Europe and the rest of the world. Through this knowledge and close collaboration with its customers, ADC Krone has developed structured, flexible fiber optic solutions tailored to the demands of each market.
With its expertise in the various country-specific regulations and authorization procedures, and its comprehensive product portfolio, ADC Krone can help its customers anticipate challenges during the planning process. Operators can then deliver their services faster and gain a competitive edge.
Author:
José Luis González, Technical Director of ADC KRONE in Iberia
