LA PAROLA A… Andrew Howell, chairman of 3GPP SA WG6

Why LTE has been chosen for Public Safety services? And how much is important a common standardization between cellular and PS (Public Safety) systems?
The move to using LTE for Public Safety services was initially started during 2011 when the FCC (in the USA) selected LTE as the long-term technology of choice for public safety communications. Since then other governments around the world have also chosen LTE for their public safety communication needs and a number of them now attend 3GPP meetings.
The main reason for choosing LTE is that it is capable of delivering better performance than the current systems in use, while the large scale deployment of LTE promises to enable cost savings for Public Safety Agencies.
LTE and the 3GPP system already meet a number of the requirements for deployment though it is recognized that further updates are needed (hence the establishment of SA6 and the ongoing work on MCPTT). In summary the aspects of LTE that make it attractive for public safety communications are: capacity, interoperability/ roaming capabilities, the broadband capabilities it offers, the evolutionary path of 3GPP technologies, the economies of scale due to commercial deployments, and security.
It is important that as far as possible there is common standardization between cellular and Public Safety systems, this is to ensure that Public Safety Agencies (e.g USA, UK, South Korea) benefit from economies of scale with regards to equipment and are able to take advantage of deployment models that leverage commercial infrastructure (as proposed in the UK). To this end a large number of companies and Public Safety Agencies have been active within 3GPP to ensure that Public Safety requirements can be meet and supported by the developing 3GPP Technical Specifications.

UK in Europe is a pioneer in renewing the legacy TETRA system towards LTE: which are the LTE functionalities that are more important / urgent for Public Safety standardization? And which are the related Business model? (National Agency ruled network Vs Commercial operators networks, a mix….)
For Public Safety authorities there are certain capabilities provided by their current networks/equipment that are needed for public safety communications. For example, Mission Critical Push To Talk is an essential function of the current public safety communication systems that are deployed using Land Mobile Radio technology, e.g. TETRA, P25, TETRAPOL and GSM-R.
To be successful as a public communications systems and to position LTE as the future technology for critical communications LTE needs to provide the means to effectively support group communication services and proximity services (direct device to device communications) , which are essential to critical communications users including public safety first responders as well as other users such as utility companies and railways.
Back in June 2013 service requirements for Group Communication System Enablers for LTE (GCSE_LTE, TS 22.468) and Proximity Services (ProSe, TS22.278, TS22.115) were approved. However, while these service requirements provide essential LTE enablers for communications independent of any particular type of media, specific service/system/EPS/application requirements are needed for development of network and application architectures, security, RAN aspects, and network and application protocols, in particular to support MCPTT (Mission Critical Push To Talk over LTE).
In addition to work directly related to enhancing LTE for public safety (i.e. MCPTT, GCSE, ProSe, SC-PTM, IOPS) there are also other work items which, although not directly linked to Public Safety and triggered by commercial requirements (e.g. latency reduction) will be very useful for public safety communications. A key advantage of migrating to 3GPP based systems is it allows public safety to benefit from enhancements driven by consumer demand.
As part of the ongoing work within 3GPP it is clear that there are different business models that need to be considered. No one business model can be said to cover all the public safety communication needs, especially as there will be different business models that suit different countries. The commercial and services related factors that drive deployment and implementation decisions differ from country to country and governments the world over are looking carefully at business costs before making commitments to system rollouts etc. However, there are a number of common factors that need to be considered in each country. These include availability of spectrum, societal/ political factors, finance, current arrangements, geography, coverage of commercial networks, commercial network operator interest etc.

What are the main features that are required to start a Public Safety service based on LTE? When do you expect the full list of required features will be made available by 3GPP?
As has already been mentioned more and more Public Safety agencies are moving towards basing their next generation systems on LTE and, with every new country that states an interest or preference in LTE this increases the potential market for LTE Public Services and helps provide further impetus to the work in 3GPP, with more suppliers and operators also becoming interested in providing services.
To support this expanded interest in the use of LTE, 3GPP has sent a clear signal of intent, shown through the focus of Release 12 and Release 13 work on the needs of public safety. In addition, a number of the key organizations involved with Public Safety related work have recognized that there is a need for a single point of focus for the application related work and this has led to the creation of 3GPP TSG SA WG6.
One of the key features of any Pubic Safety system is the ability for good communications and this is why the focus within Release 13 is to provide a robust, feature rich, MCPTT (Mission Critical Push To Talk) service. It is fair to say that the Release 13 timescales are very tight but those involved with the development of the 3GPP specifications (Public Safety agencies, operators, manufacturers, etc.) are keenly aware of the need to provide a stable set of specifications which is the primary task of 3GPP. At this stage of the specification development cycle it is maybe a little early to state exactly which features will be available within the Release 13 timescale but it is expected that the main features related to Group Communication (as specified in TS 22.179) will be met.
Replacing a public safety network is a large undertaking that requires a different kind of co-ordination compared to the deployment of commercial network. In particular the requirements, security and robustness of a Public Safety system are driven by the very particular needs of the nature and sensitivity of the work done by the users of the network. In addition there are often political aspects involved, governments do not generally deploy networks with the regularity of an MNO, which means that there are considerations other than just the availability of standards that may produce different answers in different countries.
The UK, South Korea and the US all have publicly stated timelines for deployment of LTE based systems; see the following links for reference. [nota 1]
However the situation in each country differs so, like the deployment model considerations, each country will make the decision regarding the main features that are required to start a Public Service system and will have to consider the best balance of factors for them. 3GPP is actively working with the various Public Safety agencies to ensure that the main features are supported by the 3GPP specifications in a timely manner.

Our always-connected society is relying more and more on mobile technologies for its economic growth and well being, as well as for its security. We have seen an increasing presence of government organizations sitting in 3GPP meetings, how this participation is going to affect 3GPP roadmap in the future?

With the decision taken by Public Safety agencies to move towards LTE there was a clear indication that the 3GPP based systems are already seen to be an important part of the ongoing development within our always-connected society and an acknowledgement of the key role that mobile technologies play in supporting economic growth as well as providing secure communication systems. However, it is also acknowledged that Public Safety systems have particular requirements that require further support from the 3GPP specifications if the needs of public safety users are to be fully met (e.g. robust group communication).
One of the strength of 3GPP is that participants involved in the specification development work come from a broad background covering user organization, operators, network and terminal vendors, regulatory authorities, test houses, and now Public Safety agencies. Clearly each group has differing needs and requirements but the single underlying requirement is a stable set of specifications that provides support for all the services needed.
With the increasing presence of government organizations sitting in 3GPP meetings and the involvement of Public Safety agencies there will be an impact on the 3GPP roadmap especially as a lot of the features on which Public Safety relies (e.g. proximity services, group call system enablers, etc.) also have significance for the commercial side of mobile communication. So as work develops into the future perhaps one of the key impacts on the work of 3GPP will be a convergence on requirements and services. It is likely that as work develops it will be seen that Public Safety related considerations are incorporated into work items developed for the ‘commercial’ market rather than being given separate work tracks of their own.
As with any work in 3GPP there is only a finite amount of time available in which to progress the work. This means that there has to be an ongoing review of how work is progressing and the needs of the users for whom the work is being done. It might be in the future that the public safety agencies will just look to exploit commercial developments as and when they choose.
Having said the above one of the key strength of 3GPP is its ability to respond to the changing needs of the markets it is serving. The structure of the committees is such that Public Safety related work is not focused solely on one single group, which means that the impacts on existing work will be mitigated. 3GPP also has the flexibility to organize work in a way that, as far as is possible, minimizes the impacts on non-related work items. By creating 3GPP TSG SA WG6 to concentrate on the architecture related to MCPTT services 3GPP has demonstrated an understanding that there is a need to carefully manage all the work being done (not just Public Safety related aspects) while also providing a focal point for the initial development of Public Safety related applications. 

 

Torna all'articolo


Andrew Howell

is a Technical Specialist, working as a consultant to the UK Home Office, a ministerial department in charge of immigration and passports, drugs policy, crime policy and counter-terrorism. He was elected fist chairman of 3GPP SA6 after the group was established in December 2014. SA6 is the group responsible for the definition, evolution and maintenance of technical specification(s) for application layer functional elements and interfaces supporting critical communications (e.g. Mission Critical Push To Talk.