LTE and TETRA: Winner Take All?

Will TETRA become obsolete as we see LTE gain foothold in mission critical networks?

Terrestrial Trunked Radio (TETRA) was designed as a dedicated network to meet the needs of public safety users—not just for global crisis situations, but also for services such as power and water, which are essential to the smooth running of communities. If TETRA is perfect where reliable, robust and secure communications are essential, why is the buzz on the street that we will replace TETRA with LTE networks?

Figure 1: In a January 2016 review performed by RootMetrics, Bank of America Stadium in Charlotte, NC had the fastest median upload speed; Ford Field, Detroit, MI had the lowest median upload speed.

Figure 1: In a January 2016 review performed by RootMetrics, Bank of America Stadium in Charlotte, NC had the fastest median upload speed; Ford Field, Detroit, MI had the lowest median upload speed.

TETRA Origins

Standardized by the European Telecommunications Standards Institute (ETSI), TETRA is similar in many ways to cellular mobile telephony. It began using 2G and 3G/HSDPA connectivity and can link with microwave technology in remote areas.

TETRA frequencies are mainly in the 380-470 MHz range, and as they have a lower frequency, they travel more distance making them very suitable to mission-critical features such as instant connection, push to talk, direct mode, and group calls, which were added to ensure quick instant contact in times of crisis such as those involving police and other first responders.

As late as 2013, at the TETRA World Congress, Phil Kidner, CEO of the TETRA Critical Communications Association (TCCA) said that TETRA standards were continually evolving with new features, devices, applications and infrastructure being added. Recently the introduction of TETRA Enhanced Data Service (TEDS) gave providers the ability to deploy wideband data services with the same security and resilience as TETRA.  Kidner went on to say that “LTE standards do not currently support any of the services considered vital for critical users such as group working or direct mode. LTE does not provide the coverage, enhanced resilience and security required by mission-critical users.” 

Who Uses TETRA?

TETRA became very popular in the UK where a full-fledged TETRA network was established for the country’s ESN (Emergency Services Network (ESN). But now the UK taxpayer is paying £450m/year to run the TETRA network. UK government is calling for change and considering 4G/LTE as a cheaper alternative. In the US, back in 2012, the FCC ruled to effectively extend the FCC’s temporary waiver issued in 2011 that permitted TETRA deployments in the U.S.  Some US cities, such as New Jersey, benefit from TETRA where the New Jersey Transit uses the TETRA radio system to provide a mission-critical data conduit for AVL information from buses as well as voice connectivity through a computer-aided dispatch system.

It’s also used to coordinate light rail vehicle movements and for fleet vehicle communications.  In 2012, the First Responder Network Authority (FirstNet) was created in the U.S. claiming for the first time “public safety communications will be based on commercial standards.”  It now looks like that standard will be based on LTE technology. The U.S. Government will not build FirstNet on its own, but instead will allow an existing wireless network to build and operate the network, requesting that the bidder must be able to implement coverage in all areas including highways and rural areas. The government has allocated $7 billion in funding for the network. Final proposals to build the nationwide wireless broadband publicity safety network are due by May 13, 2016 with AT&T and Verizon throwing their hats in the ring.

Making TETRA Networks Work

But can we really turn over the communications tools—those that help save lives, solve crimes, keep communities safe and connect emergency responders—to a public bid? Consider that TETRA is a mature, well-established technology that’s been working in the market for decades. TETRA uses the lower frequencies in the range of 400 MHz, thus allowing longer range suitable for areas of low connectivity, and it’s a very robust technology for communications.  For civil or emergency systems in Europe the frequency bands 380-400, 410-430, 450-470 and 870-921 MHz have been allocated for TETRA. I

TETRA uses the spectrum efficiently, and because it’s a low data network it requires relatively low bandwidth. Mission-critical communications has not been typically used for video, but given our reliance on visual streamed media in our social lives, this requirement may need changing in emergency situations. After all, a picture is worth a thousand words.

TETRA is unrivaled in terms of security and call set-up time, and gives instant access. It uses low speed packet, short data services, is resilient and is always available using site trunking to give coverage in rural areas. TETRA networks also have priority for establishing calls and have the ability to disconnect non-priority calls. Despite these many advantages, cost is an obstacle. TETRA requires its own network, which is costly to build and maintain. Would the American taxpayer be willing to foot the bill for this service even if it is for communicating during an emergency? 

Experts at the LTE World Summit in 2015 claimed that TETRA has interoperability issues with other standards such as P25, TETRAPOL, etc. The people at TETRA TCCA, on the other hand, say that TETRA is an evolving technology, noting there is room for growth if governments or the authorities value it enough. Certainly, antennas are the key link to ensuring connectivity to the TETRA network. One such antenna, the 2J7010B, possesses highly desired characteristics for critical communications such as a high efficiency of 80%, a high peak gain of 2.5dBi and omnidirectional properties. It’s the important glue in making TETRA networks work.

Ubiquitous, but…

LTE has the obvious advantage of being a global standard leveraging economies of scale worldwide. According to the industry association the GSMA, in the United States, coverage is already approaching 100% and in the Europe Union, it’s hovering at a little more than half where LTE will make up 53% of connections in Europe by 2020, and coverage will reach 91% of the population. Because LTE is widely adopted, governments do not have to spend money on creating a completely new infrastructure, setting up base stations or commissioning costly truck rolls.

But LTE, for all its ubiquity, brings the problem of low coverage in rural areas. Commercial operators and service providers are driven by business models and need to generate revenue from mass market communications, so blanketing a rural area with high bandwidth LTE does not always make sense. The overriding worry, however, is that LTE has never been tested in a large crisis situation—could the backend servers stand a tsunami flood of calls and video images being sent through an LTE network during a terrorist attack, for example?  Could we stand a situation where everyone is using the cellular network and in a disaster situation, the police and emergency services as well as the public are using the same backend technology?  In January RootMetrics tested the mobile performance of each NFL stadium during football games[1]. With 91% of America having cell phones, they say a large focus of consumer demand is based around mobile performance. The winner was Bank of America Stadium in Charlotte, NC with 14.2Mbps at the fastest median upload speed and the worst was Ford Field Stadium in Detroit, MI with 0.0Mbps. What if disaster struck during a game at Ford Field Stadium?

Another issue discussed at the most recent LTE World Summit: possible lack of adequate available spectrum in the appropriate bands and—even more worrying—LTE’s greater vulnerability to hackers as compared to TETRA networks. The most important part of ensuring that LTE services work is ensuring that antennas are highly efficient and connect to the network easily.  An example of an LTE antenna that offers strong connectivity with almost 60% efficiency across worldwide LTE bands is the 2J7050Ba antenna. A robust LTE-MIMO solution, this antenna also combines other communications standards used in the industrial, scientific and medical (ISM) sectors, in the frequencies of 915MHz, 2.4 and 5.0 GHz, with GNSS active antenna for navigation and geolocation. It has a heavy duty, high ingress protection IP69K with high gain for LTE secure connection.

LTE and TETRA: A Marriage Made in Heaven?

What’s the solution for this essential service? Will it be an all or nothing situation where one technology wins out over others?  I believe what’s best for communities is a combination of both technologies—LTE complementing TETRA. LTE offers the ability to stream high quality video and transport very large data files. TETRA availability in large population areas would afford reliable, resilient coverage. It would mean that in crisis times, when commercial networks are highly stressed and have to be limited or even closed down, TETRA would assure reliable connectivity, with LTE offering broadband services.

Ruben1Ruben Cuadras is Engineering Manager, 2J Antennas USA. Cuadras is a renowned specialist in antenna and RF solution design and services dedicated to the M2M and IoT market. He has been working for more than 10 years with M2M and IoT vendors and has a wide knowledge of certifications, carrier approvals and FCC considerations. Prior to 2J, Cuadras was Head Engineer with Taoglas. Cuadras has worked on more than 800 projects involving antennas, RF design, active optimization, emissions, approvals, noise and quiet board layout. He has been granted five patents granted with seven more pending. His experience spans the spectrum from 13.56 MHz to 25 GHz, for technologies such as 4GLTE, LoRa, 3G, CMDA, ISM, WiFi, RFID, Satellite, GNSS and others.


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