Extended Reach: the Fact File

Before discussing how to solve the problem, let’s understand it a little better. Why exactly is there a 100 m limit?

The 100 m distance limitation as codified in the industry standards (namely, ANSI/TIA-568, ISO 11801 and other cabling standards for commercial buildings) is based on the electrical limitations of twisted-pair copper cabling. As the signal travels from one end of the cable to the other, its strength is affected by certain parameters, primarily insertion loss. The longer the cable, the greater the insertion loss. Based on these performance parameters, the industry standardized on the 100 m distance.

The distance limitation represents a worst case scenario for a given application and length when conducting a signal at the cable’s maximum frequency. It assumes a four-connector channel using a 90 m trunk and a 5 m patch cable at either end.

The limit was standardized in the 1990s and has stood the test of time, even as higher-frequency applications and new cable constructions have entered the market. In that time, network equipment vendors cost-optimized their transceivers based on the 100 m limit—further solidifying it as the accepted distance boundary.

On one hand, the 100 m channel limit has simplified the job of developing reliable performance specifications for new technologies extrapolating supportable distances for each new generation of cabling.

On the other hand, the distance barrier has created a new challenge for network designers. Enterprise networks are expanding faster than the budgets that are needed to implement and manage them. This is happening as available space for additional network components shrinks. As major trends such as Industry 4.0 and the onslaught of IoT/IIoT advance, network managers must be able to support more network-connected devices and systems—throughout buildings, across campuses and, especially, at the edge. 

Another approach is to install a PoE extender in-line between the power source equipment and device. A PoE extender offers two major advantages. Each side of the link—from the power source equipment (PSE) to the extender and the extender to the device—can span 100 m, meaning network designers can essentially double the length of the channel. Some PoE extenders support daisy-chaining multiple units for spans of 500+ meters. It also provides a relatively inexpensive standards-based solution.

However, a PoE extender (aka “repeater”) is subject to the power and bandwidth limitations of the PoE technology and cable medium used. This means it can only serve a few devices. It also requires dedicated space and, without careful tracking and documentation of where extenders have been installed, management and troubleshooting can be difficult. While an extender allows networks to leverage the existing copper cabling, it requires local power, which can be difficult to access in some areas.  

Yet another option is to deploy a system of hybrid cables containing copper conductors and fiber-optic cores that feed power and data to PoE extender devices. “Powered fiber,” as it is known, has the ability to extend the network coverage up to 3 kilometers, making it a good alternative for both in-building and campus-wide applications.  

Powered fiber cabling solutions combine high-performance, low-latency fiber-optic data connectivity with a copper low-voltage direct current (dc) power connection. This enables the connection of any number of powered remote devices without the need for new conduit. With the powered fiber cable solution, the network gains access to a vast and growing ecosystem of applications, including:

• Emergency phones
• HD security cameras
• Digital signage
• Wi-Fi access points (APs)
• Small cells
• Optical LAN
• An array of low-voltage dc-powered devices

Powered fiber is widely used in situations where large areas need to be cost-effectively served by a single power and data network. These solutions, however, require more expensive fiber transmission equipment, as well as a Class 2 limited power source (LPS).

Learn more: Powered fiber fact file

A fourth option for delivering power and data to devices located over 100 m from the TR is to simply use a longer twisted-pair cabling link. While this method is not supported by the cabling standards, it is possible to use the application standards in conjunction with application testing to create a reliable link. Application standards help network designers gauge whether a specific application can run on a link segment, regardless of the cabling components used and the distance traversed.

For a more detailed analysis of this approach and the use of application standards and application testing, check out this article from Cabling Installation & Management.

Thoroughly vetted and correctly installed, the extended twisted-pair solution supports centralized management and efficient PoE delivery while reducing the number of link components and providing familiar RJ45 connectivity and installation.

There are several considerations to consider before making a decision to design structured cabling with extended reach for some edge devices. No more daunting or important than solving the issue of the 100 m distance limitation.

We’ve already touched on this issue above, but the context there was primarily performance-related (frequency, insertion loss, resistance, temperature, propagation, etc.). What about the effects of the 100 m barrier on cable and connectivity providers?

We know the velocity at which a signal travels down individual pairs in a four-pair cable impacts the cable’s ability to support extended distances. We’ve also mentioned that cabling standards are designed for a worst-case scenario and/or minimally compliant components. In response, reputable cabling and connectivity vendors build in “additional headroom” by ensuring their products exceed the standards. For lower-bandwidth devices—such as access control devices like parking lot entrance gates, emergency call boxes and security cameras—the extra headroom isn’t necessary.

Other applications do require the channel’s maximum available bandwidth. Therein lies the challenge: today’s convergent enterprise networks must support a mix of low-, medium- and high-bandwidth applications as well as those needing low, medium, and high power.

But remember, our primary goal here is extending the distance, which is affected by bandwidth and power requirements but not defined by them. In fact, in a converged network, there are many low- or medium-rate applications that benefit substantially from extended-reach cabling:

• Building environmental control automation
• Security monitoring and surveillance
• Digital signage systems
• Enhanced PoE applications
• IoT devices and sensors

The maximum distance will depend on:

• Category of cabling used
• Application speeds to be supported
• Environmental conditions such as operating temperatures

For example, a PoE+ (PoE type 2) application can support up to 30 watts of power over 150 m or more. The maximum distance depends on the speed required and type of device supported:

• Maximum horizontal distance at 10 Mbps: 185 m
• Maximum horizontal distance at 100 Mbps: 150 m
• Video surveillance (1080p HD or 4K UHD): 150 m

All numbers above from Application Guide: Utility Grade Infrastructure (UTG) 

UTG is a complete technology platform/assurance program/design approach. It unlocks a smart building’s full potential by redefining the infrastructure layer to support building subsystems, technologies and applications.

The UTG infrastructure platform features:

• Utility-ready structured cabling and connectivity from CommScope
• Advanced, tested power delivery
• UL verification of all performance and application claims

As a single converged infrastructure platform, UTG solutions bridge the gap between information technology (IT) and operational technology (OT). Now, building owners, operators and managers can navigate seamlessly between a broad range of technologies while cost-effectively improving network reliability and performance.

UTG infrastructure enables a range of existing and next-generation network capabilities, from standardized applications such as connecting Wi-Fi access points (APs) or IP phones, to those whose needs go beyond the standards, like extended distance, power, and cybersecurity.

Examples of UTG applications include:

• Building environmental control automation
• Security monitoring and surveillance
• Digital signage systems
• Enhanced PoE applications
• IoT devices and sensors
• Wi-Fi APs
• VoIP devices

Managing multiple systems on one robust platform accelerates efficiencies, increases business intelligence, strengthens cybersecurity, enhances productivity, optimizes performance and reduces operational costs.

It will take time for the standards bodies to catch up to the extended-reach performance of the UTG infrastructure platform. Therefore, CommScope has worked alongside Anixter, UL and other third-party technology experts to validate all performance claims. These efforts have resulted in UTG-specific performance standards and UTG-rated infrastructure cabling solutions. Together, they support diverse applications, systems and devices on a common network.

All performance claims and UTG ratings are independently tested and verified by UL laboratories for optimal application assurance and design on a single building platform. The results are based on real-world, definitive application testing and UTG-exclusive testing protocols. Based on UL’s testing, CommScope’s UTG solutions outperform non-UTG cabling.

Customers deploying UTG infrastructure solutions enjoy a similar level of application support available through CommScope’s SYSTIMAX Application Assurance program. This support provides the design capabilities and performance helps building owners and enterprises need to migrate with confidence. In fact, the UTG program is highly complementary with the SYSTIMAX Application Assurance program, and we believe we can build on it to extend beyond what we currently support.  

CommScope continues to focus on innovation and continual improvement, investing almost $200 million in R&D, including investments in our SYSTIMAX solutions. These investments, combined with a UL verification program to validate emerging and enhanced technologies, give our customers the satisfaction of knowing their CommScope products and solutions are indeed best-in-class. 

 

For more information on CommScope’s UTG infrastructure portfolio:

Application guide: Utility grade infrastructure (UTG)

Brochure: Utility grade infrastructure solutions

Equipment used

RUCKUS ICX7650-48ZP multi-gigabit PoE switch (ports 25 through 48):
100 MbE/1 GbE/ 2.5 GbE/5 GbE/10 GbE POH capable

GigaSPEED® Category 6A cable channel:
configured with up to four connections using GigaSPEED X10D® 2091B cable and 360GS10E cords

RUCKUS R850 AP:
Wi-Fi 6 PoE enabled, supports 5GBASE-T and 2.5GBASE-T applications

• 5GBASE-T applications are supported when the R750 AP is connected to ports 25 to 48 of the ICX7650-48ZP using up to 180 m of GigaSPEED X10D cabling
• 5GBASE-T applications are supported when the R850 access point is connected to ports 25 to 48 of the ICX7650-48ZP using up to 180 m of GigaSPEED X10D cabling
• 5GBASE-T applications are supported when the R850 access point is connected to ports 25 to 48 of the ICX7650-48ZP using up to 125 m of GigaSPEED X10D cabling

It is important to emphasize that these results were achieved using a “closed-loop” channel in which all equipment, cabling and connectors were engineered and manufactured by CommScope. While similar results using other manufacturers’ components may be possible, channel performance over extended distances cannot be guaranteed using non-CommScope components.

For a detailed analysis of the extended reach testing, results and limiting parameters, download the Extended reach installation guidelines.

Insertion loss (aka “attenuation”) is the reduction in signal strength suffered by an electrical signal as it propagates along a transmission medium, and it is present in all media types. It determines the maximum distance over which a transmitted signal can be resolved and, therefore, the maximum distance two devices can be separated while maintaining communication.

Insertion loss is usually expressed in decibels per unit length (e.g., dB/1,000 feet) and is a measure of how much a signal is weakened or reduced in amplitude as it travels down a cable. It also increases as the cable’s operating temperature increases. In a copper wire, insertion loss is caused by two main factors:

Copper loss is related to the thickness of copper used in the construction of the cable. Increasing the copper would inflate the cost of the cable and be unnecessary for the vast majority of installations that are less than 100 m in length. Increasing the conductor size also impacts the ability of the conductor to mate properly with connectivity in the form of jacks and/or plugs. Hence, dramatic increases in attenuation would be achievable only with the adoption of a new connector—something most users do not want.

Dielectric loss (aka “dissipation”) is related to the electrically lossy properties of the insulation and jacketing materials used to construct the cable. The choice of insulating and jacketing material impacts the insertion loss of the cable but also determines how the cable performs during important safety tests such as those intended to characterize flammability and smoke release. Often, tradeoffs between the electrical and safety performance of a cable dictate the types of materials employed. This is further complicated by the existence of regional safety standards such as those for plenum rated and low-smoke-zero-halogen rated environments.

It’s important to note that there are other factors that can influence insertion loss, such as resistance and heat. For example, the maximum allowed insertion loss for Category 6A (at 500 MHz) is 42.8 dB, compared to Category 6 (at 250 MHz), which is 31.1 dB. This is also why links involving smaller-gauge wires with more resistance, and where the ambient temperature is above 20°C (68°F), can require length de-rating. The higher the insertion loss, the shorter the reach must be for a signal at the far end of the link to be understandable. This is a key reason why insertion loss has such an important impact on the supported distance.

Propagation delay is the time needed for a signal initiated at one end of the channel to be received at the opposite end. In twisted-pair cabling, this time interval is impacted by the cable’s length and operating frequency, previously discussed, as well as a third factor: nominal velocity of propagation (NVP). NVP is a relative measure of the signal’s speed compared to the speed of light in a vacuum (c). Typical structured wiring cables exhibit an NVP of 0.6 c to 0.9 c, meaning the signal travels at 60 to 90 percent the speed of light in a vacuum.

A cable’s maximum NVP is dictated, in part, by physical characteristics such as the number and tightness of twists in a pair of strands. As the number of twisted pairs in a cable bundle increases, the chances of disparities in the twists among pairs also increase. The difference in propagation speeds between the fastest and slowest pairs is known as the “propagation delay skew.” As propagation delay skew grows, the network equipment has more difficulty reading the signal. Extended cable lengths can exacerbate this issue.

When we compare the different categories’ performances in light of the aforementioned parameters, it’s easy to understand the advantage of Cat 6A when we need to go further than the standard 100 m:

• At 100 MHz, Category 5e has an insertion loss maximum of 24 dB, while Category 6 is at 21.3 and Category 6A is at 20.9 (per TIA channel specifications). Remember: The lower the dB for insertion loss, the better.
• Common 6A cable and cordage gauge is larger (thicker) than for other categories, which improves insertion loss, resistance and SNR parameters.
• Cable heating is lower for 6A when transmitting the same current and wattage for PoE purposes, which makes possible larger cable bundles.
• As previously mentioned, first-class 6A solutions are carefully tuned up to provide lower signal reflection.
• All of the above advantages, combined with the inherently superior performance for alien crosstalk, make Cat 6A the perfect choice.