1. TETRA Inter System Interface (ISI)
Good morning Ladies and Gentlemen
The Association has received many enquiries regarding the Intersystem interface from both Korea and other countries planning TETRA networks.
We therefore felt that it would be useful to give a short update on the status of the standard for the ISI and for the TETRA Interoperability Profiles and test plans for the standard,
This presentation is based upon some of the questions we have received.
An update and review of specific issues
John Cox
CEO TETRA MoU Association

2. Inter System Interface (ISI)
An important part of the TETRA standards suite
Defines interoperability between radio networks
Published by ETSI (European Telecommunications Standards Institute)
Korean National version published by TTA (Korean Standardisation Organisation)
The ISI is a fundamental and important part of the TETRA standard and defines interoperability between radio networks.
The standard is published and maintained by ETSI the European Telecommunications Standards Institute and we understand that a Korean National version has now been published.
TETRA based national radio systems are now operational or becoming operational in Finland, The Netherlands, United Kingdom, Belgium, Austria, Sweden and Greece and as we will hear later trials of the ISI have been conducted by three of these countries.

3. ISI usage International cross-border cooperation ISI Country A
Country B
It is important to understand that the ISI is not only about cross border cooperation and working. It may be used in a number of ways.
Some examples are:
Across national border between countries for cooperation

4. ISI Usage National Multivendor Cooperation ISI Subnetwk B Subnetwk A
National multi vendor environment where two organisations decide that they need to cooperate

5. Local In Country Cooperation
ISI Usage
Local In Country Cooperation
User A Network
User B Network
ISI
Local in country environment where two user organisations need to cooperate

6. Interoperability Certification Process
Managed by TETRA MoU Association
Ensures genuine multi-vendor market for operators, users and suppliers of TETRA
TETRA Interoperability Profile (TIP) specifications are produced to…
Guide the implementation and
Give detailed instructions for conducting Interoperability test sessions
Test sessions are carried out under the supervision of an independent Italian Government Organisation, ISCTI
As you heard in the previous paper, the Association plays a key role in the IOP process which ensures a genuine multi vendor market and user choice of supply.
Much of the past work has concentrated on the Air Interface but increasingly attention is on the network interfaces and in particular the ISI. As more organisations plan and implement their TETRA networks so the importance of the ISI has grown.
The Test Sessions are carried out in a multi-vendor environment by recording and analysing the details of interaction between equipment from different manufacturers and under the supervision of an independent Authority. This supervisory role is currently covered by ISCTI, a Governmental Institution that reports to the Italian Ministry of Telecommunications. Successfully passed Test Sessions result in Interoperability Certificates being issued by ISCTI to the participating manufacturers. The Certificates provide results of all conducted test cases and the verdict of the Authority.

7. Status of ISI TIP’s – June 2005
Comprehensive set of TETRA ISI TIP’s have been published for the implementation of operational network solutions:
Individual Call
Mobility Management
Short Data Service
Group Call
Voice Transmission Format
Lower Layer Protocols
Test Plan Documents
Original Plan – reviewed by Member’s Enquiry (ME)
Revised Plan – about to re-enter the ME stage
ISI and related Test Sessions
Air Interface Migration tested April 2005 (required for terminals to roam across an ISI)
ISI test
Planned for later in 2005
Awaiting manufacturers to inform TETRA MoU Association that they are ready
The Association has already published TETRA ISI TIP’s for Individual Call, Mobility Management, Short Data Service, Group Call, Voice Transmission Format and the Lower Layer Protocols. These published TIP’s form a comprehensive set of documents for implementation of operational network solutions. The TETRA ISI Test Plan documents are still under development, the first Plan has been through review with the Member’s Enquiry (ME) and the resulting revised plan is expected to enter the ME shortly. The first test sessions to certify the Air Interface Migration signalling, which is required for terminals roaming across the ISI were conducted in April The Association will be organising formal test sessions for ISI, when two or more manufacturers are ready.

8. 3-Country Pilot - Interworking Verification Project
Tested interworking between national networks
Security agencies from Belgium, Germany & the Netherlands participated
Equipment
Networks from Motorola & Nokia
Terminals from Motorola, Nokia and other manufacturers
Phase 1 report concluded “… that the European TETRA standard provides the communication requirements for the future emergence of a new dimension of co-operation of security agencies in Europe.”
Full report available at
As you may be aware, a verification project known as the 3 Country Pilot, has been running in Europe for some time. The purpose of this project is to test interworking between national TETRA networks, to determine the operational processes for cross-border cooperation and to verify the suitability of the TETRA ISI for this cooperation The Pilot Project was a final key activity in the Schengen agreement, which pointed to TETRA, after successful completed cross-border tests. The project was conducted between the security agencies of Belgium, Germany and The Netherlands together with their TETRA system suppliers Motorola and Nokia. TETRA radio terminals from third parties were also used in the testing. The end report of the 3-Country Pilot phase 1 was published in November 2003 and concluded ” … that the European TETRA standard provides the communication requirements for the future emergence of a new dimension of co-operation of security agencies in Europe.” The report is available at
You will hear more detail about this Project in a presentation later today.

9. Developments after the 3-Country Pilot
Functional Requirements Specification developed
Produced by combined group working from:
Belgian and Dutch Security Agencies
Motorola and Nokia
Scope – detail the communicating technology needs based on the development scenarios (the practical tests carried out by multi-agency teams during the pilot)
Specification now an ETSI Technical Report – TR
After the 3-Country Pilot phase 1 Belgian and Dutch security forces together with Motorola and Nokia produced a Functional Requirements Specification to detail the communication technology needs based on the developed scenarios. This Specification has now been converted to an ETSI Technical Report TR : ”Functional Requirements for the TETRA ISI derived from the Three Country Pilot Scenarios” that will be published by ETSI in the near future.

10. ETSI Project TETRA – additional ISI specifications
TR analysed by ETSI Project TETRA and TETRA ISI TIP Working Group
New work item established, supported by
Astrid (Belgian Public Safety)
ISC (The Netherlands Public Safety)
Motorola
Nokia
New requirements for TETRA ISI TIP specification identified
Additional functionality for group attachment through the ISI to the TETRA ISI Mobility Management standard
ETSI Project TETRA has been replaced by TETRA Technical Committee
This new report text was analysed by ETSI Project TETRA and the TETRA ISI TIP Working Group and as result a couple of new requirements were identified in addition to the contents of the current TETRA standards and TETRA ISI TIP specifications. Consequently, a new work item has been opened within ETSI Project TETRA (supported by Astrid/Belgium, ISC/The Netherlands, Motorola and Nokia) to include the additional functionality for group attachment through the ISI to the TETRA ISI Mobility Management standard.
At this point it I would like to deliver a very important piece of information.
Until very recently, the TETRA standard was under the management of ETSI Project TETRA which as a Project was subject to funding and annual review. Very recently, the ETSI management agreed that ETSI Project TETRA (EPT) should transfer to a permanent ETSI committee called ETSI TETRA Technical Committee This confirms that TETRA will now have permanent maintenance and support within the standardisation body thus further confirming its long term future.

11. Update on specific functions supported by current ISI TIP specification
Priority call & Emergency call
Can be delivered through ISI allowing emergency call to continue on other side of ISI
Individual call
Test plan currently at ME stage – anticipated to be completed by the end of June 2005
No restoration during migration – not identified as necessary by 3-Country Pilot teams
Group call
Not covered in ISI TIP as calls can be re-established by Late Entry or by pushing PTT once
The current ISI TIP specifications support delivery of call priorities – including the emergency call priority – through the ISI thus allowing emergency call to continue properly as an emergency call at the other side of the ISI. Test Plan for Individual Call is currently in Members’ Enquiry with comments resolution meeting expected to take place in June.
The current versions of the ISI TIP’s do not assume call restoration of individual calls to be performed during migration and neither has that been a requirement from the Public Safety users in the 3-Country pilo). Group calls on the other hand are re-established implicitly either by having Late Entry service activated for the group or by the user pushing the PTT key once. Thus the ISI TIP’s does not separately address restoration of group calls.

12. Encrypted functionality and the ISI
Current ISI TIP’s are ready for air interface encryption with Dynamic Cipher Key (DCK)
Over The Air Rekeying (OTAR) and Group Cipher Key (GCK) functions could all be included if they become user organisation requirements
The current versions of the ISI TIP’s are ready for air interface encryption with Dynamic Cipher Key (DCK) method, in which the air interface encryption is enabled by the user authentication, which takes place between the radio terminal and base station. More complex functions such as Over The Air Rekeying (OTAR) and Group Cipher Key (GCK) functions could all be included at some future time if they become user organisation requirements.

13. Group attachments across the ISI
Current situation
ISI TIP’s assume that group attachments are done in the network where the radio is registered using a local ‘agent’
New ETSI work item identified
Work in progress to allow the network identifier part of the group number to be delivered across the ISI to enable direct attachment from the other side of the ISI
TIP and test case will be updated when the content of the new standard is finalised
The current versions of the ISI TIP’s assume that group attachments are done in the network where the radio is registered by sending the attachment request to the local ”agent” of the group in that network and receiving the acknowledgement via that ”agent”, in line with the current standards. As explained, there is now a new work item in ETSI to allow the network identifier part of the group number to be delivered across the ISI to enable direct attachment from the other side of the ISI. The TIP and the associated future test case will be updated when the content of the new standard is known.

14. Dynamic Group Number Assignment across the ISI
DGNA handling logic is same as for Group Attachments:
DGNA is performed in the network where the radio is located
DGNA message sent by the dispatcher located in the same network as the radio
Current ISI TIP’s do not support DGNA between networks
In line with how the current versions of the ISI TIP’s handle group attachments it is assumed that DGNA is performed in the network where the radio is located, i.e. the DGNA message would be sent by the dispatcher located in the same network where the radio is located. The current ISI TIP’s does not support DGNA between networks.

15. Radio Enable/ Disable across the ISI
Amendment to current ISI TIP was identified in 3-Country Pilot
ISI TIP Working Group suggestion:
Enabling/disabling should be linked with authentication
Home network of a stolen radio would not grant other networks a permission to authenticate that radio
Modification to the ISI standards NOT needed if this proposal is accepted by users
Concerning the radio enable/disable service, the 3-Country Pilot specification identified a need for amendment. Currently the ISI TIP Working Group has suggested a method to the 3-Country Pilot group in which the enabling/disabling is linked with authentication so that the home network of a stolen radio would not grant other networks a permission to authenticate that radio,. If this proposal is accepted by the users, no modification to the ISI standards are needed.

16. Packet Mode Data Call across the ISI
IPI (Internetwork Packet Interface) is Packet Data Gateway standard for TETRA
ETSI reference is ETSI TS ‘IP Interworking (IPI)’
Same interface as ALREADY used to connect TETRA packet core networks to the Internet
Additional specification to cover packet data NOT required
There has not so far been any plan to incorporate packet data in the ISI. There is an existing packet data gateway standard for TETRA, known as the IPI (Internetwork Packet Interface), published as ETSI TS “IP Interworking (IPI)”. Technically that is the same interface as the one used to connect TETRA packet core networks (or other mobile core networks) to the Internet. Packet data is thus not seen as an issue for the ISI TIP’s.

17. End to end encryption across the ISI
Current ISI TIP's support end-to-end encryption
ISI delivers TETRA voice frames transparently through the interface
SwMI’s should be expected to transport end-to-end encrypted communication as long as they are:
Compliant with SFPG recommendations, and
Can support ISI connectivity
It is considered that the current ISI TIP's already support end-to-end encryption because the ISI is delivering the TETRA voice frames transparently through the interface. Therefore any two SwMI’s – which are compliant to the SFPG recommendations – and able to support ISI connectivity - should be expected to transport end-to-end encrypted communication

18. Future revisions of documents
Drafting work for TIP’s and Test Plans is done by voluntary resources from the manufacturers
Manufacturer priorities typically depend on demand from the operators and users
In general, ISI work has high priority
Required amendments are quite minor
Time required to make the identified revisions is shorter than the time required to produce the ISI Test Plans
Conclusion
‘revision’ work would NOT be the limiting factor in the time-to market for interoperable TETRA ISI
One question we are frequently asked is when will all of the documentation be complete?
There is no straightforward answer to this questions. It has to be understood that the drafting work for TIP’s and Test Plans is in practice done by voluntary resources from the manufacturers and the priorities of the manufacturers typically depend on the demand from the operators and users often defined in contracts. However, in general the ISI work has high priority on the agenda of the TETRA community and we believe that the required resources will be identified by the participating manufacturers. Understanding that the required amendments to the TIP’s are quite minor, our overall estimation is that the time required to make the identified revisions is shorter than the time required to produce the ISI Test Plans that are still nonexistent, and thus this ”revision” work in reality would not be the limiting factor in the time-to market for interoperable TETRA ISI.

19. Sources of further information
The three sources of information presented are
The TETRA MoU web site
Three country pilot web site
The ETSI web site

20. Chief Executive Officer
Thank you
John Cox
Chief Executive Officer
TETRA MoU Association