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LTE for Critical Communications – Mind the Step

Time to Turn Page

Terrestrial Trunked Radio (TETRA) standard was first introduced in 1995 by ETSI as a mobile communications system for mission critical operations: public safety, rail transport and military among other use cases. It has been proven to work well in more than hundred countries, but now it is starting to show its age.

The biggest drawback of TETRA is obviously the low data rate, with TETRA we are still talking about kilobits per second. Due to this – and a few other issues – LTE (3GPP Long Term Evolution) and its future extensions are emerging to be the dominant design. I suspect we will see major share of the current TETRA operators migrating to LTE in next couple of years.

Time to Define the Deployment Strategy

Having assessed the situation, I think TETRA operators migrating to LTE have basically four alternative deployment strategies. On high-level, the options are:

  1. Dedicated: Build a completely new own LTE network
  2. Hybrid: Build own LTE in selected areas/network functions, lease rest from MNO(s)
  3. Lease: Fully leased LTE network from a MNO
  4. Multi Lease: Fully leased LTE network from several MNOs

All of the above alternatives are fully viable migration paths. And all of them come with their own benefits and caveats. The main point is that TETRA operators should carefully study those alternatives before jumping into any bandwagon. This is a decision that will have permanent impact on network Cost, Security, Reliability and Deployment Time.

Deployment strategy has permanent impact on cost, security, reliability and deployment time

Network Cost

Building a Dedicated LTE network has obviously the highest Total Cost of Ownership as it involves a significant upfront Capex. Hybrid network, which also comes with a Capex element, has the second highest TCO. Leasing the network from an MNO means that the only cost elements are the network Opex and device costs. Furthermore, the leasing may become even more cost-efficient if sourced from multiple MNOs.

Dedicated LTE comes with the highest TCO

Security and Reliability

With reliability, I actually mean everything related to the service availability – including capacity, coverage and resiliency issues. Obviously, the highest security and reliability comes with a dedicated network (1). And thinking the coverage – commercial operators might have little or no incentive to build radio coverage in locations with low subscriber density. And yet the same locations might be of strategic importance for mission critical communications. This means repeaters and specific indoor solutions and hence increased cost (or lost cost savings) for the public safety network.

A dedicated public safety LTE network (1) yields clearly the highest security and reliability. In all other deployment strategies (2, 3, 4) the network design will eventually be a compromised combination of mission critical and commercial mobile communications.

Dedicated LTE gives the highest security and reliability

Deployment Time

Dedicated (1) and Hybrid (2) approaches are the only deployment strategies requiring a serious rollout and deployment time. The former is naturally the slower option as the whole network would be built from scratch. Leasing the network from one or multiple MNOs involves only the time for completing the contract negotiations and sourcing the devices. This on the other hand, is not necessarily a short task. In any case, one can conclude that leasing will guarantee the shortest time for a fully functional LTE.

Dedicated and Hybrid approaches require serious deployment time


In short, one can summarise the alternative deployment strategies as follows:

  1. A dedicated LTE is a decision for maximum Security and Reliability with the expense of maximum network Cost and Deployment Time.
  2. A leased or hybrid LTE is a decision for relief in network Cost burden and Deployment Time with the expense of compromised Security and Reliability.

How high the TCO of a dedicated network will be? How does the cost compare to other deployment strategies? What kind of security and reliability risks are present with leased LTE networks? Can I afford or mitigate the risks?…These are the questions the decision makers should be asking themselves right now. Having multiple years of experience in the field I know that the answers are not the same in different markets.

The fact is that the needs of mission critical communications have grown beyond TETRA capabilities. Or maybe the needs were there already 20 years ago, but it’s just that with modern technologies we can now meet the criteria. In any case, I think the time has come to turn the page. If you’d like to discuss more about the issue, call/email me and let’s sit down together!