The electric utility sector is seeing a continuous investment in modernizing the communication infrastructure to enable grid modernization. The interest in mission-critical private communications has never been higher. Over the last two years, we have seen rapid development with the private LTE ecosystem from Tier 1 base radio equipment vendor product community, spectrum availability, and complementary products and services, making an end-to-end solution viable. Many utilities are advancing from their development phases - business case/feasibility level, into public service commission approvals or other regulatory body approvals, and then into pre-deployment planning, design, and early deployments. We are seeing this development within all electric utility sectors - co-ops, munis, and IOUs. Over a dozen utilities have purchased spectrum for private LTE. They are either in the design and initial deployment stages, about another dozen are deep into the business case stage, and many others are just beginning their analysis. The private LTE development has rapidly advanced following the key milestones highlighted below:
Utility Field Area Network Communications Evolution
Most utilities with larger service territories have been adding new applications that require communications backhaul for over 25 years. Their networks are a mixture of 1990s vintage through the most modern wireless and fiber optics infrastructure. Much of the field area networks are comprised of proprietary serial communications that have met the needs for Distribution Automation programs that were typically deployed starting around 2005 to the current state. Still, now we are seeing the need for sometimes a ten-fold increase in the number of end-devices to be deployed, new applications such as for customer and utility provided DER, more sophisticated routing through the ADMS, and upgrading of aging mobile voice systems. And all this with a preference to move away from proprietary communication protocols. The communications evolution has evolved significantly since the 1980s/1990s with many utilities now using a mixture of the following communication technologies for their mission-critical Field Area Network applications.
Why Private LTE?
First off, private LTE is not for all utilities as other technologies, or a combination of technologies will simply be more effective. However, the author sees consistent trends with some of the common utility themes driving the business cases for private LTE:
- Private LTE is global standard. Utilities are not at the mercy of proprietary technologies if a vendor discontinues a product line or goes out of business. Therefore, having a long-life cycle with the spectrum and infrastructure is much more likely than many other technologies.
- The utilities existing DA and substation communications backhaul is a hodge-podge of older communication technologies similar to the list above,
- Land Mobile Radio (LMR) is not going away! At many utilities their land mobile radio systems have aged, and the mobile voice spectrum is insufficient to scale to newer digital product lines. Commerical cellular is still not mission critical,
- The number of new DA devices, the number of new DER locations, and the latency expectations are all increasing. While the current technologies have met the needs, the products are at the end of life, now failing at a much higher rate and unable to scale,
- Many utility’s AMI systems are now about ten years into their life cycle, and many of these utilities are now working on their next generation AMI migration plan. While the current AMI has been highly effective, new requirements are surfacing for behind-the-meter use cases requiring open protocols and greater bandwidth than AMI delivers. Some utilities are evaluating the use of private LTE as their communications for their next generation AMI or even performing as a hybrid solution where private LTE metering could be deployed with locations where behind the meter DER, EV, or PV communications are preferred. Other utilities are comfortable with commercial cellular in the meter or sensor as opposed to private LTE. The AMI vendor community also is stepping up to enable private LTE as the transport of metering-related use cases
- Private LTE offers greater control of the product life cycle. The life cycle is a key driver in the business case. The longer life cycle is expected, with LTE being the sole protocol for 5G cellular across the globe. The industry is expecting continuous backward/forward evolution of LTE. If you recall, cellular from 2G to 4G consisted of several technologies – various GSM and CDMA vintage (CDMA 2000, TD-SCMA, TD-CDMA, etc.), sometimes different by country or carrier, etc., often leading to shorter life spans. With private LTE, the utility has control of their own life cycle for their base station and end devices
- Also noteworthy is that LTE offers strong security layers. With the above list of drivers, the private LTE business case typically has layers of scenarios i.e., Private LTE just for the FAN, with adding as a mobile radio system replacement, for next generation AMI or a hybrid for Behind the Meter use cases, others.
Filling Private LTE Coverage Gaps
For many utilities, ~70/80%% of their end devices are in urban/suburban areas, but just ~20% of the end-devices can comprise 50% or more of the overall service territory. Therefore, in some cases, purchasing spectrum to cover the entire service territory footprint and deploying base stations/towers to cover the secondary markets can be cost-prohibitive. Because of this, some utilities are electing to use a hybrid with the use of FirstNet, commercial cellular, or other technologies with the use of LTE end devices where possible. The business case will typically model various deployment scenarios if private LTE becomes difficult to justify across the entire footprint. However, one of the key benefits of private LTE is the flexibility to design and build it where desired versus where the commercial cell carriers have elected to provide 4G/5G cell sites.
Spectrum for Private Wireless
To operate private LTE, the minimum requirement is 1.4 MHz Transmit/1.4 MHz Receive or transmit/receive at 3 MHz. However, individual channels can typically consist of 180 KHz channels. Spectrum of 3 MHz or greater is available at 900 MHz from Anterix. To offer true 5G. this requires 5 MHz Tx/5 MHz Rx. This spectrum is available within CBRS, 600 MHz and 1.6 GHz.
At 600 MHz, several other spectrum choices exist from Dish Network, US Cellular in their markets, and a few other sources. Private LTE infrastructure can also be deployed over 3.5 GHz referred to as Band 48. In this band, several utilities purchased exclusive spectrum for their use through an FCC auction. This is referred to as PALs (Priority Authorized Access). The registered and unprotected 3.5 GHz is referred to as GAA (General Authorized Access). The GAA 3.5 GHz (CBRS Spectrum) is available to be registered through one of the four Spectrum Access System coordinators, but this GAA CBRS spectrum does not have stringent rules to protect from interference as the PALs and other licensed spectrum provides.
In more rural or secondary market areas or lower density service territories, we are seeing some utilities deploy with 220 MHz or 700 MHz spectrum through spectrum brokers such as Select Spectrum, Choctaw Communications, or wide-band 900 MHz spectrum (100 KHz channels) from Space Data Corporation. However, at 220 MHz and narrow-band 900 MHz, the underlying technology is not private LTE. Also, new developments were released earlier this year by Ligado Networks at the 1.6 GHz band. This is another emerging spectrum/technology that can meet many utility needs in both rural an urban areas.
Under the LTE umbrella (3GPP) is a solution protocol named Narrowband Internet of Things (NB-IoT. This is also gaining momentum in the utility sector. NB-IoT is gaining acceptance for field applications that are difficult to reach locations for the lower bandwidth applications such as DA backhaul. NB-IoT requires less power can operate on batteries and applications that can tolerate a few seconds of latency that may only require hourly or less frequent transmissions.
Robust Equipment Vendor Community
The vendor community for private LTE is strong. Let’s start with the consulting firms with deep insights with private LTE. Companies such as Black & Veatch, Burns & McDonnell, and West Monroe Partners all have key resources to conduct business cases, evaluate spectrum alternatives, and provide regulatory guidance, design, and deployment support. The base station vendors are classified as Tier 1 trusted brands – Ericsson, Nokia, Motorola, Atos, and others. The private LTE end devices are manufactured by many leading firms - 4RF, GE, Telit, Cisco, MulitTech, Aviat Networks, Nokia, Motorola, Sierra Wireless, and others. Companies such as Anterix can bundle solutions together from within the vendor community. We are also seeing new business models surface, such as Network as a Service, where a third party can manage the infrastructure on behalf of the utility.
In prior generations, utilities typically lacked spectrum but had a strong equipment vendor community. We now have spectrum available but at a premium cost. As stated above, some utilities will find the cost of the spectrum and the cost of the Private LTE infrastructure to be a business case barrier, yet others will find positive cost/benefit return. We are fortunate to have a solid consulting community, spectrum available, and Tier 1 equipment vendors. The author also believes once the chip technology supply chain stabilizes and the competition for LTE chips and other form factors intensifies, the end device price points will decline over time with hyper competition expected.
While this article focuses primarily on private LTE, as stated above, other choices can be better for some utilities. For example, some utilities are building their next generation AMI with utility-owned fiber to all their AMI take-out points and then building their next generation wireless AMI with significant resiliency/redundancy and with the preference to use AMI as the communications backhaul for everything in their Field Area Network and Behind the Meter and IoT assets. Some utilities are deploying fiber to the home or partnering with broadband providers and bypassing large wireless investments. Other utilities have found solutions at 220 and 700 MHz. Also, using unlicensed spread spectrum and cellular represents viable solutions or gap fillers. Yet Private LTE will prove to be best for others.
Typical Approach for the Communications Infrastructure Journey
Regardless of the technologies selected, most utilities, whether they are co-ops, munis, or IOUs, typically follow a similar staging/phasing development process as described below.
Conclusions
Communication infrastructure is a crucial building block for grid modernization. The reliability/resiliency of the communications infrastructure is now believed to be just as mission critical as the electric grid. Selecting the communications infrastructure for the future starts with a marriage between the utilities’ strategic and grid modernization plans. The evaluation could conclude private LTE could become the long-term solution for the FAN, substations, metering, LMR, Behind the Meter, and other applications combined with a fiber optic backbone. However, more communication breakthroughs have occurred in the last three years compared to the last ten years. Take a close look at Private LTE; you’ll like what you see.