• May 4, 2021

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Powering Strategies to Enable Smart & Healthy Buildings

By Rodger Hyle

In a world of evolving and expanding technology, one factor remains constant: the ever-increasing need for greater bandwidth and increased power consumption at the network’s edge. New applications such as smart and healthy buildings continue to place more and more pressure on already constrained copper-based enterprise networks. This dynamic is driving the need for new networking architectures and innovative power system platforms to support them.

What Are Smart & Healthy Buildings?

At the heart of a healthy world is a healthy building. Smart and healthy buildings are dynamic smart facilities with connected solutions for healthy people, healthy places, and a healthy planet. These unique solutions improve operating efficiency, boost productivity, and increase occupancy. In addition to being “smart,” healthy buildings solutions help to ensure the safe return of people to the workplace. New technology such as Johnson Control’s OpenBlue Healthy Buildings enables spaces to be used dynamically while powering adoption of the “new normal,” promoting health and wellness in the post-pandemic environment. Some of these solutions include:

Challenges of Smart Healthy Buildings

Copper-based LAN networks of yesterday are already stretched to their limits, especially now with the proliferation of policy-controlled edge computing and new artificial intelligence (AI) driven sensing and monitoring systems. With the Internet of Things (IoT) and Wi-Fi 6, we are seeing a whole new multi-device convergence with bandwidth and power requirements that are further straining existing copper-based network infrastructures.

The Passive Optical LAN (POL)

Fortunately, there is a better way. A way to accommodate the new bandwidth challenges for the LAN of today and tomorrow – the POL.

What is POL?

Built on the foundation of the passive optical network (PON), the POL is a high-bandwidth, highly secure, more reliable fiber-optic-based technology. Its architecture implements a point-to-multipoint network topology where converged wireless, voice, video, and smart building applications can be transported at 10+ Gpbs speeds, via single optical fibers, to serve multiple users inside buildings and across an extended campus.

A POL consists of an optical line terminal (OLT), fiber optic cabling, optical splitters, and optical network terminals (ONTs) to transmit multiple services. An optical splitter, as shown in Figure 1, splits downstream signals and combines upstream signals to and from the connected devices, all on one strand of single mode fiber using a technique known as wavelength division multiplexing (WDM). Additionally, since the ONTs can support multiple devices, POLs require less cable (and the labor and infrastructure to install it) to support the network.

Key Benefits of a POL

• Reduced Costs
• Significant savings in CAPX, OPEX, and construction costs
• Considerably reduced cable weight and fire loading
• Futureproofing
• Provides unlimited bandwidth
• Upgrade only endpoints for migration
• Scale & Reach
• Easy moves, adds, and changes (MACs)
• No 300-feet limitations

Synergies with POL, Wi-Fi 6, & 5G

By leveraging the same high-bandwidth fiber infrastructure in a deep fiber POL network, synergies exist between POLs, Wi-Fi 6, and private 5G networking solutions. Regardless of if Wi-Fi 6 and 5G coexist or converge, enterprises will require a robust, fiber-optic data transport infrastructure to be able to realize all the benefits of 5G technology. If Wi-Fi becomes the access technology of choice to deliver 5G services, there are many distinct benefits of subtending Wi-Fi 6 wireless access points (WAPs) onto a POL.

POL Network Architecture

Figure 1 | Source: 2019 BICSI Winter Conference & Exhibition

Challenges to Implementing POLs

A POL solves the bandwidth problems for networking challenges but also introduces a new challenge: how to provide power and resiliency to all the required parts of the POL including the OLT, ONTs, and non-Power over Ethernet (PoE) compliant network edge devices. Without a copper infrastructure, PoE to the ONT is not an option. Plus, some edge devices simply have too high of power requirements or require AC power, which is not compatible with PoE. Simply put, just as with so many other advances in technology, power becomes the enabler to technological advancement.

Strategies for Powering the POL

There are two main areas to be concerned with to provide power and battery backup in a POL.

• The OLT located at the main distribution frame (MDF)
• The ONTs units and other high-power devices located at the network edge

The method to provide power to the OLT equipment is well known and standardized in the industry, where the best practice of provisioning carrier grade power and battery plants are routinely followed. However, the options at the network edge, where the ONTs and other high-power consuming devices live, can vary widely. Two main topologies exist for supporting these important network elements – local power and line power.

Local Power

The conventional means of powering ONTs and/or remote devices is through a DC power supply or UPS connected to a local electrical outlet. This local power technique is costly, requires batteries at each remote device, and promotes downtime during extended power outages. In some cases, if not already existing, electrical outlets need to be installed by licensed electricians.

Concerns with Local Powering:

Line Power

Fortunately, there is an alternate method known as line powering. Line powering systems use copper cabling run alongside or together with fiber in both vertical and horizontal spaces to deliver power to remote devices from a centralized source. By capitalizing on National Electric Code (NEC) wiring standards, line powering parallels many of the key benefits of an all-optical networking infrastructure, enabling PO
Ls to realize long-term key advantages more fully. Today, line powering platforms are grouped into two main categories for enterprise applications – Analog (class 2) and Digital ElectricityTM (DE).

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Analog vs. DE Line Powering for POL

Analog (Class 2)

In a class 2 line powering architecture, a 48Vdc power plant and batteries are located in a central site, such as a main distribution frame (MDF) or intermediate distribution frame (IDF) equipment room. This 48VDC power is converted or “boosted” to 57VDC and is then distributed over standard 12AWG to 20AWG single or multi-conductor copper cable or composite (hybrid) fiber cables to energize remote devices. These (100W) current limited power circuits service devices with a range between 30 to 90W and a reach up to several hundred feet based on wire gauge. These circuits meet the NEC requirements for class 2 circuits, thus qualifying for class 2 wiring methods. This means traditional copper cable can be used in this architecture, eliminating the need for conduit or armored cabling, and can be installed by telecommunications technicians rather than licensed electricians.

A class 2 line power solution is a very useful tool in the toolbox of any power system designer for enterprise networking projects. Class 2 line power solutions are ideal for enterprise applications like POL or smaller indoor DAS deployments with shorter distances and lower power radio access units (RAUs). Although class 2 line powering systems are ideal for distributing low power from IDF closets to the network edge, using a class 2 system exclusively reduces the value of the key class 2 benefits. With the class 2 distribution located in the IDF locations, class 1 circuits (either 120/240VAC or -48VDC) would still need to be run to each IDF telecommunications room to support either a distributed or centralized power system architecture. Class 1 circuits do not qualify for class 2 wiring methods, which means conduit or armored cabling would be required to be installed by licensed electricians to connect the MDF to the IDF locations. In addition, this model greatly reduces the flexibility to move or scale the IDF/splitter locations in the future.

DE

What About AC-Powered Edge Devices?

There is a misconception that very few options exist for providing power and backup for AC-powered ONTs and edge devices. Traditional line powering systems can only provide nominal 48VDC power at the network’s edge. So, conventional wisdom suggested the only option was to provide a UPS at the network’s edge, which means a local powering architecture is the only option for AC devices. However, DE is different and can provide both 48VDC as well as pure sine wave AC to power devices located indoors or outdoors up to a mile away from the main MDF location. This is all backed up with a single power plant using highly reliable telecommunications-grade batteries that are used in macro cell sites today.

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Power System Architectures

Several different power system architectures exist to incorporate these ideal line powering platforms into the network infrastructure. The sections below describe each power system architecture using deep fiber topology examples including the positives and negatives of each (pun intended).

• Distributed architecture
• Centralized architecture
• Centralized digital architecture

Distributed Architecture

In a distributed system architecture, a main telecommunications-grade power and battery plant resides at the MDF and it is provisioned to be able to provide power and battery backup to only the electrical loads at the MDF location, mainly the OLT. In addition, smaller rectifier shelves and battery plants required to support class 2 distribution systems need to be provisioned at each of the IDF locations where the passive spitters reside. The class 2 system will in turn provide up to 32 circuits of power to supply the ONT devices via separate copper or hybrid cable that can be run according to class 2 wiring methods. In this model, however, there needs to be work done by local electrical contractors to run 208V-240VAC (class 1) circuits using either armored cable or conduit to each of the zone IDF locations. This method is common when using a class 2 power distribution system since the MDF may be too far away from the ONT locations or the edge devices may require too much power for the class 2 system.

Pros:

• The benefits of using a mid-span class 2 system from IDF locations to power each ONT provides flexible ONT placement

Concerns:

• Space must be found for power equipment at the IDF locations
• Multiple power and battery plants must be maintained
• Electricians need to install class 1 AC electrical circuits into each zone IDF if they do not exist
• In this model, only the class 2 circuits can be run in same pathway as fiber

Distributed Power Architecture

Centralized Architecture

The centralized system architecture is almost identical to the distributed system architecture except there is no need for individual rectifiers or battery banks in each IDF location. In this model, the centralized power and battery plant is provisioned to handle the OLT loading and all the ONTs (including any connected devices they serve with PoE) throughout the entire network. Class 2 power distribution shelves will still need to be located in each IDF location as with a distributed system architecture. But rather than electricians having to run AC circuits to energize class 2 systems at each IDF/splitter location, a -48VDC circuit will be pulled from the centralized DC power plant located at the MDF. These circuits are still classified as class 1 circuits, which means they will need to be either armored cable or enclosed in conduit.

Pros:

• The benefits of using a mid-span class 2 system at the IDF locations to power each ONT provides flexible ONT placement with carrier-level survivability
• Single centralized power and battery plant
• Central monitoring and control point for all power circuits
• No heavy, bulky power plants/batteries in each IDF

Concerns:

• Electricians needed to install -48VDC class 1 electrical circuits into each zone IDF
• Main power plant needs to be upsized to offset cable losses to IDF locations
• In this model, only the class 2 circuits can be run in same pathway as fiber

Centralized Power Architecture

Centralized Digital Architecture (CDA)

A CDA blends the benefits of DE with the benefits of a class 2 system. With a CDA, a centralized, carrier-grade power and battery backup plant, located in the MDF, energizes both the OLT and is used to supply significant power thousands of feet away via DE. These bulk digital transmission circuits can be used to supply as much as 2,000W of power to each flexible splitter location where it can be converted into class 2 circuits (<100W each) and safely distributed to up to 32 ONTs per zone. Or, it can be sent directly to alternative locations, such as 5G remote radios, using class 2 wiring methods requiring neither conduit nor licensed electricians. Hybrid copper/fiber cables can be installed by telecommunications technicians in either vertical or horizontal spaces minimizing cable pulls and drastically improving speed to install. This strategy enables complete site freedom and flexibility for passive splitter locations as well as high-power radio placement. When DE is used in conjunction with a class 2 system, network engineers have an effective radius of up to 1.75 miles for resilient ONT positioning from the MDF.

Pros:

• Single, resilient, and redundant centralized power and battery plant
• No heavy, bulky power plants/batteries in each IDF
• Central monitoring and control point for all power circuits
• Speed to install vs. traditional AC installations
• No class 1 circuits between the MDF and IDF, no electricians – no conduit
• Dedicated circuits can be run directly from the MDF to edge device locations
• Indoor/outdoor and AC/DC edge device locations are supported
• Future 5G private networks can leverage POL fiber and DE power infrastructure
• Entire network power cabling can be run in same pathway as fiber

Centralized Digital Power Architecture

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Summary of Key Benefits for Centralized Digital Power Architecture:

Fast

• Reduces or eliminates class 1 AC or DC circuits beyond the MDF
• Speed to install and more control of network deployment

Flexible

• MACs easily as spaces change and reconfigure
• Both power and passive LAN systems can easily scale by upgrading only endpoints
• DE and class 2 power can be run in same pathway as fiber

Safe

• Power-limited circuits are touch safe
• 500 safety checks per second on every DE circuit

Survivable

• Promotes network survivability and reduces monitoring complexity with a single redundant central head end power/battery system

Smart

• DE provides integrated policy control for remote monitoring and autonomous control at the zone level for remote power cycling and energy management decisions

Green

• Reduces proliferation of lead acid batteries in local UPS at ONT/edge locations
• In modern photovoltaic (PV) or wind assisted DC architectures, DE is extremely energy efficient and can qualify for leadership in energy and environmental design (LEED) credits

In conclusion, as technology evolves and expands, new bandwidth and power requirements continue to put pressure on existing copper-based enterprise networks. A new, centralized, and digitally powered POL addresses these concerns by providing an optimized network architecture that is highly flexible, scalable, and survivable.

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Sources:

johnsoncontrols.com/openblue/openblue-healthybuildings

pcmag.com/news/wi-fi-6-may-be-faster-but-its-also-more-challenging-for-it

apolanglobal.org/blog/passive-optical-lan-cost-comparison/

tellabs.com/benefits-of-subtending-wi-fi-waps-onto-a-passive-optical-lan-network/

voltserver.com/

Figure 1, 2019 BICSI Winter Conference & Exhibition