By Scott Neal and Darek Wieczorek | Mission Critical Magazine
About a decade ago, the commercial wireless sector launched networks based 4G LTE. The public-safety community, via the First Responder Network Authority (FirstNet), made a similar decision to deploy 4G LTE for its nationwide public safety broadband network (NPSBN), which is being implemented in concert with AT&T. From the beginning, it was assumed that the NPSBN would leverage, on some level, commercial infrastructure.
Very good reasons exist for why LTE has been embraced by the commercial wireless and public-safety sectors, starting with its name. Long Term Evolution was intended from its inception to provide a technological foundation for next-generation networks that would be highly adaptable as market conditions and the needs of service providers and end users changed. LTE first was proposed by Japan’s NTT Docomo in 2004 and was ratified by the Third Generation Partnership Project (3GPP) in 2008. The first 4G networks followed two years later.
Apart from its moniker, LTE is a great choice because it is suitable for all kinds of demanding data applications, from short messages to high-quality video. It also integrates a point-to-point voice communications capability. And, because the inherent latency is low and can be controlled, there are indications that the technology is suitable for even the most sensitive situations. In tests conducted last year at the National Renewable Energy Laboratories (NREL), latency below 30 milliseconds (ms) consistently was achieved, even with high-traffic volumes.
Standardization of LTE networks permits reasonably priced and power efficient chipsets that enable wireless devices to be manufactured to provide high throughputs suitable for the widespread deployment of the internet of things (IoT). LTE networks are able to mix both high- and low-level densities of devices, making it feasible to install sensors and modems on individual utility poles, for instance, to monitor and report network integrity. Large electric power utilities are responsible for thousands of poles that support cables and equipment, the status of which is important to isolating faults that may interrupt service.
Due to the robust schema used for their over-the-air (OTA) protocol, LTE networks provide a high level of interference resiliency. Adaptive modulation schemes allow the information flow to continue, albeit at a slower rate, in the face of interference or network congestion. While the information flow may slow, it is unlikely to be completely interrupted.
LTE has a very impressive list of advanced features, giving it unparalleled functionality and flexibility regarding quality of service (QoS), including priority and pre-emption; advanced mobility; and scalability from a single station (eNodeB in LTE jargon) to very wide-area networks.
RF spectrum is also a significant factor. The public-safety and utility sectors long have relied on LMR systems for their mission-critical communications because such systems are highly evolved, reliable and secure. However, they also are highly complex and expensive to deploy, and they operate in RF spectrum that is very crowded, which creates significant capacity and interference concerns.
The spectrum issues that afflict LMR systems are nowhere near as onerous concerning LTE networks, and promise to be even less so due to a FCC order that was issued in May 2020. The commission ordered reconfiguration of the 900 MHz business industrial (B/I) band to allow broadband operations, such as LTE, in airwaves that traditionally had been allocated for narrowband communications. The new rules divide the band, with 4 megahertz set aside for incumbent narrowband operations and the remaining 6 megahertz made available for broadband operations.
Finally, LTE is a global standard that was designed with high levels of cybersecurity protections from the very beginning. Advanced end-to-end encryption and provisions that ensure authentication, such as subscriber identification module (SIM) cards, are just two of the important cybersecurity features provided by LTE networks.
In the public safety sector, many devices and systems that enable the transmission of mission-critical data to and from personnel in the field are available, particularly in the law enforcement community. These include: body-worn cameras, fixed and vehicle-mounted cameras, thermal-imaging cameras, unmanned aerial vehicles (UAV), closed-circuit television, smartphones, holster sensors, biometric sensors, gunshot detection/location systems, facial-recognition systems, automatic vehicle location (AVL) systems, GPS and mobile data terminals (MDT)/rugged laptops/tablets.
Collectively, all of this gadgetry exists to provide personnel in the field and their incident commanders with unprecedented situational awareness, and to provide commanders with vital health and safety information about their personnel. However, the ability to achieve this depends on access to a broadband communications network. Without one, most of the devices and systems referenced above would be unusable because the size of the data files they generate would choke a narrowband system, causing significant latency and perhaps preventing data transmission altogether.
The same holds true in the utility sector. The critical nature of electric power utilities has been recognized for a long time and most are continually improving reliability in many areas. Critical needs for robust and efficient data communications networks have emerged as utilities pursue increased reliability of electric power delivery in their fast-changing environments. These include the smart grid, distribution automation and advanced meter reading. New challenges have emerged as well, related to the quickly growing renewable energy sources, the expected exponential growth of electric vehicles, and new forms of energy storage.
There are also practical day-to-day factors that must be considered. For instance, let’s say that during a storm a tree falls, and in the process downs electric power lines. In such a circumstance, the ability to remotely turn off power to those lines from a control station located miles away, within milliseconds (ms), potentially will save lives and/or hundreds of thousands of dollars in equipment damage and labor.
All of this requires broadband communications capabilities to handle the vast volumes of data that will be gathered, transmitted and processed, and to deliver the ultra-low latency demanded by some applications. LTE is the best choice for delivering these capabilities.
Commercial versus private
Public-safety agencies and electric power utilities have numerous opportunities that require robust, reliable and cost-effective broadband communications. LTE networks are capable of meeting these needs.
Two ways exist to leverage LTE: commercial networks and private networks. FirstNet’s NPSBN leverages commercial infrastructure, but with a critically important caveat: priority and preemption are granted to public-safety entities so that the network is available to them whenever they need it, for however long they need it. This is not true for utilities. While they are considered NPSBN secondary users, and thus would have limited pre-emption privileges, they could be bumped off the band during times of heavy use by primary public-safety users.
At first glance, it might seem logical for utilities to turn to commercial wireless carriers for LTE. But, such carriers are profit driven and thus focus on the enormous consumer markets. That translates into limited flexibility and responsiveness to the needs of industrial entities, even large, major investor-owned utilities. Thus, they are unable to make all of LTE’s flexibility and advantages available to industrial entities within a guaranteed service level agreement (SLA).
Further, coverage and capacity are designed based on population and do not necessarily cover utilities’ critical areas. Because commercial wireless carriers have to put their consumer customers first, can any electric power utility be assured that its critical control functions will not be impaired when millions of wireless subscribers are streaming the Super Bowl on their smartphones? The answer to that question is a resounding no.
Consequently, private ownership of a custom-built LTE network may be the best approach for the utility sector because it provides the winning combination of highly suitable technology with total network control. It is the only way that utilities can ensure that they will have the bandwidth and throughput they need at all times. The advantages of such networks are numerous:
• Coverage. This is the king of any wireless system’s requirements. With private ownership, the number and location of sites can be designed up front to meet the requirements of the organization; they also can be adjusted as needs change, such as if a new power plant is constructed or an old plant is shut down.
• Capacity. When device density does not coincide with the general population, or changes due to specific activities, additional sites can be provided on a permanent or temporary basis as needed to support the required data volumes.
• Configuration and customization. In the consumer world, voice communications may have priority over other types of traffic, primarily data. In a network owned and operated by an electric power utility, data communications may require preferential treatment — the need to disconnect faulty circuits could take priority over any other traffic, for example.
• Upgrades and maintenance. The ability to plan upgrades or maintenance so that they do not interfere with the utility’s primary mission, as opposed to depending on a commercial carrier’s schedule, is a key element for mission-critical operations.
• Expansion. Electric power utilities exist in a dynamic environment. Mergers and acquisitions are common and such events may require network expansion. Experience has shown that incompatibilities between the respective communications networks can delay or diminish integration of the involved utilities after an acquisition or merger.
• Access to multiple spectra (licensed, unlicensed or shared). The ability to mix and match spectrum can be advantageous because doing so may provide technical and financial advantages. For example, not all applications are equally sensitive, and devices that operate in unlicensed spectrum may be significantly less expensive than equipment operating in the licensed airwaves. Also, different frequency ranges are characterized by different coverage performance; hence, mixing and matching them is another important design optimization tool.
• Security. In addition to the cybersecurity features inherent to LTE, private ownership of a network provides an opportunity for total isolation from public networks, if so desired.
• Fault tolerance.This is crucial and often cited as the commercial wireless networks’ Achilles heel; commercial carriers design high levels of coverage overlap in high-density population areas and are just not that concerned about losing a site for a while. They also are reluctant to invest in physical security, backup power, redundant backhaul and other measures required by electric power utilities. With a privately owned network, utilities are in total control of the fault-tolerance aspects of network design.
• Fixed cost/revenue potential. Last, but not least, private ownership provides not only a potentially higher level of control over costs, but also, in some circumstances, provides income opportunities borne of sharing excess resources with other entities.
But what about public safety agencies? Do any scenarios exist that would justify a private LTE network? The answer to that question is an equally resounding no — at least for the foreseeable future.
A case could be made, on a high level, that a private LTE network could make sense for an urban agency that has many users within a relatively small footprint, including secondary and tertiary users such as departments of transportation, public works and motor vehicles, and has decided to use LTE for all of its voice and data communications.
A compelling reason for doing so would be to realize complete visibility into the network, something that public-safety agencies never will receive with the NPSBN, despite repeatedly asking for it, or any other commercial network for that matter. Such visibility would enable agencies to better understand the strengths, weaknesses and vulnerabilities of the network. But public-safety agencies are forced to trust the commercial service providers’ networks are mission-critical grade and capable of meeting their needs.
But even in cases such as the one described above, whereby private LTE would make sense in theory, a lot of things would have to happen for it to make sense practically, and it will be a decade or two before those things are realized fully. One concerns mission-critical push to talk (MCPTT) over LTE networks. This capability has come a long way — there was a time when many in the public-safety community believed that it never would come to fruition — and continues to evolve.
However, capabilities that are essential for an emergency response environment still are lacking. Foremost among them is an inability of MCPTT over LTE to provide public-safety-grade, point-to-multipoint voice communications, which is a hallmark of LMR systems. Generally, the group communications capabilities provided by LTE networks, commercial or private, while making progress, are still inferior to those provided by LMR systems.
The utility sector relies heavily on data communications and its voice communications tend to be one on one with group communications much less common. But, while data continues to become more and more important in emergency response, voice is still king and will remain so for the foreseeable future. So, it will be many years before it makes sense for a public-safety agency to abandon its LMR network. Thus, implementing a private LTE network to handle its data needs while continuing to use an LMR system for its voice needs would be extremely cost prohibitive for any public-safety agency.
Simply put, LMR systems are great for voice but limited for data, while LTE networks are great for data but limited for group voice communications. Again, PTT voice is king for public safety, while data is king for utilities. So, point-to-multipoint communications represent a huge hurdle to clear for MCPTT over LTE. An equally tall obstacle concerns talkaround, or direct unit-to-unit communications. This is a vitally important capability, especially for fireground communications. It enables field personnel to communicate with each other when they cannot connect to the LMR system’s repeater, a common occurrence in places where signal penetration is problematic, predominantly in large and/or concrete structures such as warehouses, parking garages, shopping malls and basements. In a mayday scenario, talkaround capability can mean the difference between life and death for firefighters.
While it can be argued that the point-to-multipoint and talkaround issues will be resolved eventually, it just won’t happen in the foreseeable future. But, even when it does happen someday, it likely won’t be enough to convince a public-safety agency to abandon LMR and consolidate all voice and data communications onto an LTE network.
This circles back to the aforementioned lack of transparent visibility into commercial networks. Without it, there is no way for public-safety agencies to assess the performance of such networks regarding coverage, capacity and fault tolerance, or the ability of a network to continue operating properly in the event that some of its components have failed. Regarding fault tolerance, it is important that a public-safety agency understands the network’s backup capabilities, from knowing which sites have generators to knowing how traffic is rerouted in the case of an outage. This knowledge is crucial to gaining the agency’s trust, and without it, no agency will put all of its communications eggs into the LTE basket. Recall the earlier assertion in this article that private LTE only would make sense for agencies that decided to use LTE for all of its voice and data communications.
The only conclusion that can be reached, at least for right now, is that private LTE networks do not make sense for public-safety agencies. It is an entirely different matter for utilities. While LTE networks on a high level will meet their communications needs, the standard services offered by commercial wireless carriers will not. Consequently, utilities, particularly electric power utilities, seriously should consider deploying a private LTE network to realize all of the advantages identified in this article.