Legacy Radio Technology – Time to Move on to 3GPP Based Networks!

Many countries are in the process of moving off legacy, voice centric, radio technology for their first responders. The new networks are based on 3GPP standards like 4G/LTE with a roadmap to migrate to 5G, the same technology that mobile operators around the globe are using. Staying too long on the legacy technology increases time to benefit as well as introduces risk.?

Summary

The legacy Emergency Services Networks (ESNs) are usually based on radio technologies like APCO25 or TETRA (based on region) that have been around for about 3 decades. They’re very voice centric and can at best offer data speeds of up to 120 Kbit/s, if data is supported at all. The same technologies are frequently also used by airports, oil and gas companies and public transport to mention a few users of Land Mobile Radio (LMR) technology. The use of mobile data has permeated society at large and first responders needs these services too for things like video or drone footage from an accident scene, access to blueprints or transmitting cardiograms from an ambulance to be assessed by a remote physician. Relying on two separate networks and two separate devices is far from optimal for first responders. Staying too long on aging legacy technology hampers productivity, introduces technical risk and becomes more and more expensive as you get closer to sunset of a technology. Users of legacy ESN and LMR technologies should plan for a sunset around 2030 and migrate away by year end 2028 to have some margin.

The need for data

Having access to reliable and reasonable data bandwidth has become key for many first responder organization. Being able to get access to information from an accident scene increases the safety of the first responders as well as reduces time to rescue as relevant information helps optimizing the decisions. In the same way, being able to stream video from the accident scene, body cams or drones to a gold command center improves significantly the ability to effectively command and control the first responder resources compared to a voice only situation. This is highly applicable also to ambulances where the ability to transmit vital signs and cardiograms for review of a remote physician that can then prescribe the correct treatment.

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The timing is right now

As usual, timing a move from a legacy technology to a modern technology is key, especially if the technology is used in a mission critical way. The difference between leading edge and bleeding edge is significant, not only in financial terms but also when it comes to credibility. The UK was one of the first countries to announce the intent to migrate from the nationwide TETRA based Airwave network to LTE. The announcement came back in 2014 and EE (now part of BT) was announced as the network provider in late 2015. The original intent was to move to LTE by end of 2019. This was subsequently moved to end of 2022 ?and the latest plan is to start in 2024 and complete in 2026. The major driver in the UK for the early transition was that the regulatory authority denied Airwave additional spectrum needed to upgrade the TETRA network to support limited data rates. The biggest delays has been caused by slow build out of additional LTE base stations to achieve full geographic coverage and the development of a mission critical Push-to-Talk (PTT) application. Originally, the contract with EE called for extending their existing network with some 500 additional base stations. That was subsequently increased to 700. This proved to not be enough so the UK government is building an additional 292 carrier neutral sites to achieve the needed geographic coverage. The UK clearly ended up on the bleeding edge side by moving prematurely and under stress.

?Standards based Mission Critical Push-to-Talk (MCPTT) was first introduced in the 3GPP Release 13 (R13) in 2016. Additional improvements came in R14 (2017) and R15 (2018) to increase its usefulness. Standards based MCPTT solutions are now available from leading vendors such as Ericsson, Motorola Solutions, Nokia and Samsung. FirstNet in the US launched its first MCPTT service in 2020.

In short, the underlying technology is now ready since a couple of years and proven. There is really only one desired remaining feature left, the ability to interoperate with legacy ESN technology to ease the transition for large first responder organizations and enable different organizations to migrate at different points in time while still being able to communicate with each other. There are several interoperability initiatives on its way. One example of such technology is the InterWorking Function (IWF) standard introduced in R17 (mid-2022). FirstNet is piloting ?such a solution from Samsung and Etherstack. Another such technology is Radio-over-IP (RoIP) introduced in R12 (2015) with products from companies like Catalyst and Cubic. FirstNet introduced an RoIP based solution based on technology from company Cubic in 2021. A third solution suitable for more regional implementations is from company InstantConnect that allows integrating LMR voice into IP based talk groups.

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The Risk of staying too long

By not migrating to new technology, the time to benefit by providing good data connections to first responders will be delayed or forcing first responders to leverage multiple networks and devices to get the job done.

The main problems arising from staying too long include:

• There is a cost overhead of keeping a legacy network while increasingly adding mobile broadband services as well
• Many first responders end up carrying two devices
• As fewer and fewer are buying the legacy technology, vendors in the space reduces R&D to a minimum or sell of their product portfolio. Innovation will disappear, no new devices will come to market and equipment will get harder and harder to procure leading to higher prices, grey markets and second hand equipment.
• Supply chain issues may arise if many organizations are forced to move in a short time period.

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Additional users of legacy ESN technology

The same legacy ESN technology that first responders use on a national level are also used by other companies or organizations on a regional, plant or campus level. These organizations could be airports, oil and gas companies or public transport to mention a few users. This is usually referred to as Land Mobile Radio (LMR) technology. What’s applicable to a nationwide legacy ESN is equally relevant for a local or regional deployment of the same technology.

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What are the unique features in legacy ESN?

Some of the most important characteristics:

• Typically operates in low spectrum, around 380-395 MHz, which is great when building out a cost effective geographical coverage. The drawback is that it’s difficult to support any substantial data speeds.
• In the case of TETRA, the ability to use a TETRA terminal as a relay (see figure 1 below for an illustration)
• Ability to communicate Terminal to Terminal when there is no network available

?The different forms of 3GPP based ESN solutions

Unless it’s a very small country to cover, the only realistic solution is a Private Public Partnership (PPP) where an established MNO provides a slice of its public Radio Area Network (RAN) to be used by the ESN. These agreements are usually very long, typically around 20 years. The existing MNO RAN almost always needs to be extended with additional base stations to provide the needed geographic coverage. There is typically three different routes to take, see figure 2 below. Procuring either the entire ESN as a managed service or the RAN component from a MNO usually makes a lot of sense since there is a lot of very specific competency required to plan, build and operate a RAN.

?What are some of the mitigation strategies when migrating away from legacy ESN to 3GPP based solutions

Problems or issues that need a mitigation strategy typically tend to appear in the following areas:

• Geographical Coverage – Accidents and disasters tend to frequently happen outside of densely populated areas. Mobile Network Operators (MNOs) tend to focus their coverage on where people (customers) live, work or travel.
• The quality of the network service delivered – what will be the characteristics of the “slice” of the MNO radio network that is provided as the ESN Radio Network
• Vendor lock in – There has to be a way to migrate/move to another vendor if the first one fails to deliver or at the end of the contract when it’s time to re-tender.
• Maturity of software solutions offered.
• Support during disasters – Hurricanes, landslides, flooding, tsunamis or massive power grid failures have a tendency to wipe out or deteriorate existing infrastructure. If existing equipment remain operative, the capacity may need to be increased to support large amounts of first responders.

?Possible mitigation strategies include:

• Geographical Coverage – The coverage requirements need to be clearly documented and how the cost for reaching the enhanced coverage requirements should be handled. Coverage may be required to include coastal areas, lakes as well as remote wilderness. There needs to be an SLA around the minimum throughput and concurrent users as well.
• The quality of the network service delivered – There needs to be SLAs around minimum service levels for the “slice” and things like pre-emption (giving first responders higher priority including bursting into other slices and “throwing out” consumers and corporate users if required). There is usually a need to have more than one first responder profile and different SLAs per profile. In most countries, government entities can order shutdown of mobile communication in a certain area or base station (typically used to deprive terrorists communication). In a modern ESN this needs to be implentement so that the ESN slice survives and only the other slices are disabled.
• Vendor lock in – Solutions should be based on recognized 3GPP standards like MCPTT, IWF or RoIP. Proprietary solutions should be avoided. Great care needs to be taken around how a move to another MNO RAN in the future would work given the need for coverage improvements.
• Maturity of solutions offered – Proposed solutions, including command center applications, should have reference installations by now. If the requirements can only be met by custom development or extensions of existing products on the market – verify that the requirements are really “must have” and not just “nice to have”.
• Support during disasters – Ensure that the RAN provider have rapid deployment equipment available that can be airlifted or immediately transported to a disaster area, complete with satellite backhaul and staff on call. Another aspect that needs to be covered is having a plan to power base stations in case of power grid failure including refueling generators.

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Recommendations

It’s time to execute the migration plans for both first responder organizations as well as other organizations that use legacy radio technology. The vendor landscape for legacy radio technology is already contracting and staying will become expensive and risky. Plan for legacy radio technology to effectively sunset around 2030 and plan to be off by YE 2028 to have some margin. Historically, legacy technology tend to stay around way too long after the major vendors have left the market and leaving it to opportunistic small vendors with questionable viability. There needs to be plans and provisions in place to prevent that some organizations lag behind and requests continued service beyond what is reasonable and safe.

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Sources

This article is based on publicly available information from mobile operators, mobile equipment manufacturers, ESN country organizations like FirstNet as well as my own analysis.

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