The case for public safety spectrum

Mission critical broadband for use by public safety services could prove vital in the fight against crime and terrorism. But if it is to be relied on in future it must be secure and robust, and that calls for dedicated spectrum, argues Motorola

The case for public safety spectrum

Every major disaster report since the 1950s has highlighted the weakness of communications among the public safety organisations responding to the emergencies.

The inquiry in the UK into the 7/7 bombings in London serves as a useful reminder of the difficulties caused by lack of adequate interoperable communications among the various emergency services. TETRA was not in use across the emergency services in London at the time and the events of that day served as a driver to accelerate the rollout and extend coverage, especially on the London Underground network.

The communication problems encountered in the events of 7/7 go a long way to making the case for Governments to provide dedicated public safety spectrum, not just for mission critical voice, but for mission critical broadband.

The advantages for public safety organisations to have access to services such as real-time, high quality video streaming co-ordinated with voice traffic are many. The question is: ‘How can it be delivered?’ The options are: a dedicated public safety service (PSS) network, like the current TETRA networks; a shared service run on commercial networks; or a mix of the two.

The problem with the last two options is that public safety communications have unique and stringent requirements in terms of integrity, security, coverage, capacity, reliability, availability, redundancy and reconfigurability.

Given these requirements, the risk of trying to implement a shared system on public cellular networks, which will allow emergency service communications to be prioritised at very short notice, is highly problematic.

Commercial networks are driven by different requirements. They are not optimised to meet the operational requirements of mission critical data applications, including secure data transfer, nationwide coverage, guaranteed availability and control.

A shared network scenario would require ‘pre-emptable capacity’, whereby the commercial networks would guarantee to clear spectrum for emergency purposes on demand. There are a number of risks associated with this in terms of making it failsafe and it is debatable how willing the mobile networks will be to provide such a service – if this is not part of the license agreements from day one.

That leaves dedicated PSS networks. Voice capacity and thus spectrum for PSS was initially estimated back in 1994. The current dedicated narrowband and wideband 380-470MHz network allocation of only two 5MHz-wide blocks for PSS in many countries is not sufficient to meet future needs. They are limited in capacity and the volume of data they can provide, and congestion on the TETRA network may necessitate the use of insecure communications for data communications, which would be a problem in a major emergency.

The integrated broadband services now emerging require more bandwidth for use by PSS. Consequently, that means additional dedicated spectrum must be reserved.

European Governments are aware of the problem and 27 countries, including the UK, have agreed on the need for more spectrum for today’s mission critical voice and future data services. Spectrum below 1GHz will be the most cost effective for society, as spectrum above that level will incur much higher infrastructure rollout costs.

So, the key task is to find a tranche of spectrum for broadband use below 1GHz. And as far as the users are concerned it would be preferable if a pan-EU allocation of spectrum could be found to facilitate common standards and interoperability, even though different parts of the same frequency bands might be used in each country. It has been suggested that the ideal for public safety services would be two blocks of 10MHz between 400MHz and 800MHz.

So, the question is: will European regulators reserve some spectrum for dedicated public sector broadband? Harmonised spectrum planning takes many years to bring to fruition. Work on harmonisation was initiated three years ago and is progressing slowly, but there is a pressing need to ensure that dedicated spectrum is allocated now. So, where can spectrum be found?

It is a task fraught with difficulty. The UK, for example, has several ‘no go’ areas. The 800MHz and 2.6GHz are due to be auctioned off in 2011. None of the NATO bands will be released for decades. The current 2012 Olympic band allocations are being reserved, but that allocation will be withdrawn at the end of the event.

However, 380-430MHz is the European home of public safety voice and wideband communications. In the UK, the independent regulator Ofcom is likely to be directed to find capacity somewhere. Motorola believes there are two logical possibilities.

Let us first consider the tuning range of TETRA (380-430MHz). It would be very complex to clear the band, but it is possible. But there is still only enough for wideband here. It is possible that ‘ransom strips’ of bandwidth could be taken from current incumbents such as the Ministry of Defence, Arquiva and the Department of Health.

The 450-470MHz band is another possibility for wideband but it is heavily used and in the UK uplink/downlink frequencies are reversed compared with the rest of Europe. The 600MHz band is another possibility, but only in the UK.

That leaves the next digital dividend below 790MHz as a possibility for broadband spectrum or alternatively in the NATO bands below 380MHz.

There is no easy answer as to where dedicated public safety broadband spectrum can be found. In the end it is a political question: what should the balance be between HDTV channels, military capability and the effectiveness of the emergency services? Today, the emergency services only have 0.9% of harmonised spectrum.

But as stated at the outset, there is an accepted need that spectrum must be found. Threats to security are higher than ever and the subject of dedicated spectrum is on the agenda of the UK and other European countries.

The technology for real-time video exists or is being refined. Spectrum can, and indeed must, be found.

However, at present there is a lack of an effective voice from the public safety user lobby. There is a real risk that the lack of a clear voice could be mistaken for a lack of need. The opportunity needs to be seized now.

If this window is missed there is a real risk that it will be 15 years or more before effective public safety and security broadband provision is available. The case for dedicated PSS spectrum is compelling.

This is an advertisement feature from Motorola

Written by Wireless magazine
Wireless magazine

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