Smart Amplifiers, Smart Results
By Chris Topazi
As many operators are moving toward DOCSIS 4.0-capable network upgrades, much of the industry is migrating toward more intelligence deeper in the network. Continuing the trend from distributed access architectures (DAAs) using remote PHY, active network elements are becoming a vital means of collecting metrics and enabling faster and more efficient troubleshooting. In this article, we discuss ongoing trials of this technology at our company, including some of the potential that we see as transformative to our operational models.
What is a “smart” amplifier anyway?
Traditionally in North America, RF amplifiers—whether system amplifiers or line extenders—have been pure RF devices, providing two-way amplification, a fixed diplex filter, and plug-in modules for control of gain, equalization, automatic gain control and other functions. While cost-effective and simple to understand and operate, these amplifiers have some distinct disadvantages. Namely:
- Network technicians must stock many possible values of plug-ins in their vehicles, including plug-ins for each vendor’s equipment that is present in their service area.
- Technicians must be physically present at the network element to make any adjustments or measurements.
- No audit trail of changes made to the network element, leading to outdated and incorrect documentation.
- Technicians must visit each amplifier in a cascade to rebalance the gain structure at time of construction or periodic maintenance.
Smart amplifiers address each of these disadvantages and provide further benefits as well, including:
- Software-controlled RF circuitry, reducing or eliminating the need for plug-in modules.
- Capability for remote configuration of RF parameters, along with the ability for local control through an app on the technician’s phone or tablet.
- Mechanisms for authorization and tracking of changes made to network elements via software.
- In some cases, auto-leveling functions that can align entire cascades with the press of a button.
- Additionally, smart amplifiers can also provide metrics and telemetry back to a central monitoring location to be used in problem identification, localization and ticketing. We will dive into this in more detail, as it is of massive operational value.
How do smart amplifiers connect to the network?
Smart amplifiers, similar to DAA nodes, need a network layer connection back to a central controller. This is achieved through means of a transponder device within the amplifier housing. Transponders are not really new technology—in fact, most operators use transponders in their power supplies today for monitoring health and status of those devices. For traditional RF amplifiers, because there was little to monitor and control outside of power supply voltages and temperatures, it was difficult to justify the cost and extra power required for transponders. In the latest iterations of amplifiers, though, software control of RF circuitry is commonplace, and enhanced monitoring capabilities are available, leading the industry to accept the additional capital cost incurred for operational advantages.
Transponders come in many varieties, with the main differentiation at the physical and MAC layers. Fortunately, control of these devices and metric collection do not require high-bandwidth connections, so many protocols provide sufficient capability.
Some legacy transponders use DOCSIS 2.0 or DOCSIS 3.0 chipsets, hardened for outdoor environmental requirements. These chipsets are rapidly becoming obsolete and are harder to obtain. This potential obsolescence is leading the industry toward other standards. One of these transponder types is HMS or the later standard of HMSv2, which is intended to be compatible with the frequency splits used in DOCSIS 4.0. HMS and HMSv2 are much more cost-effective but provide less bandwidth to each network element for control and metric collection. Finally, there are transponder options for using the LoRaWAN technology that is used widely in IoT applications. There may be future options as well, with even more capability.
As with any product with multiple options, there are pros and cons for each. As you consider which transponders to use in your network applications, these are all factors to weigh—and keep in mind that systems designed to interface with transponders may have to be capable of communicating with multiple types.
What are considerations when deploying smart amplifiers in my network?
As we have begun trials and are examining future-state architectures for our smart amplifiers, we are examining many cross-functional areas that should be considered by any operator employing these new capabilities. These include:
- Which type(s) of transponder will be deployed?
- What controllers / aggregation points are needed to interface with those transponders?
- Where, physically in my facilities, do those controllers need to reside and how do they scale?
- What types of data should be collected and how frequently?
- Which other internal systems should have this data fed to them, and what mechanisms exist for doing so?
- Who should have access to this data?
- Who should have authorization for control of RF parameters and to what extent?
- What auditing capabilities are necessary?
- What guardrails should be placed programmatically to reduce human errors in configuration?
- What provisioning, automation and process steps are necessary for bringing these devices online, replacing failed devices and tracking where they are?
- What security measures are necessary to protect my network from harmful actors?
- How is accuracy of network topology data maintained—to ensure that network technicians are sent to the correct location to resolve issues?
And those are just scratching the surface. As we move forward with proving the concept and early deployments, there will be many more questions to be answered.
Wow. Those are a lot of factors to consider. Is this smart amp thing truly worth it?
Yes, yes, and more yes! Let’s consider the operational impacts for a moment, shall we?
Beginning with construction, imagine activating an amplifier by scanning a QR code with your phone. The transponder is provisioned, the amplifier name and geographic location are associated to it, its location in the network is recorded—including the preceding amplifier in the cascade, and a template for the RF parameters is downloaded to the device. The configuration on the amplifier matches the design completely. If the design isn’t quite perfect, and minor modifications need to be made, the installation technician pulls up the app, modifies the configuration (within guardrails and limits), and the configuration is saved back to a central repository of “as-built” data. Now, a complete birth certificate for the amplifier is stored. No more mismatch between design and as-built data, no question about what plug-ins are installed in the amplifier.
Now, it’s time for maintenance and troubleshooting. Without smart amplifiers, we are reliant on other systems monitoring cable modem RF parameters to identify that an issue exists and to try and localize it. With smart amplifiers, though, if the input level to the amplifier dips below a threshold, or the slope of the input signal is outside configurable limits, it can generate an alarm and inform the operator. Using topology data, those alarms allow much faster localization of the problem and can give an exact cable span in the location for the maintenance ticket. And that annoying upstream ingress? A skilled technician can attenuate legs of amplifiers while watching a spectrum view, traversing the tree and branch structure from the comfort of the indoors, finding spans with ingress sources. Soon, it will be possible to achieve this programmatically. Further reducing the time spent locating the network issue, increasing accuracy, and greatly improving time to repair—a win for both our technicians and our customers. Even better, data from smart amps can be used in conjunction with other metrics to provide a more holistic view of network health.
This sounds amazing! Is there anything that these smart amps can’t do?
At the end of the day, nothing replaces the skill and expertise of a well-trained network technician. It is still required for a human to resolve the underlying network issues. These technologies will not address the underlying issue or “self-heal” the network. They are simply a force multiplier—identifying issues faster, routing technicians to the most impactful impairments the first time around, and localizing issues to a single span between amplifiers. These improvements will likely result in higher customer satisfaction and service reliability. This also leads to an improved employee experience for technicians. Doesn’t everyone love moving down an amplifier cascade in freezing or sweltering weather, in aerial plant with backyard easements, while avoiding aggressive dogs (and maybe homeowners)?! So yes, we hope to achieve tremendous improvements in operational efficiency with the use of these amplifiers.
Wait a minute…you said something about results! So…what are they?
You’ll have to stay tuned for future Broadband Library articles from my colleagues for these. We are in the beginning stages of our journey, now having deployed these smart amplifiers to several of our markets. We are currently conducting trials of their effectiveness to validate the expected improvements. We are actively using the new smart amp functionality in the service areas where these have been deployed to see how much time and effort is saved over traditional troubleshooting methods. We are also forging ahead with plant designs and architecture using smart amps to help transform our network in preparation for DOCSIS 4.0.
Until then, consider having your amplifiers help you work smarter, not harder.
Chris Topazi
Principal Architect
Cox Communications, Inc.
Chris Topazi is a Principal Architect at Cox Communications, where he is responsible for testing and development of deployment guidelines for DOCSIS 3.1/4.0 technology. He has worked in the cable telecommunications industry for more than 25 years, including the past 12 years at Cox. Prior to joining the Cox Communications team, Chris designed and developed products for both headend and outside plant applications at Scientific Atlanta and Cisco.
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