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TETRA Inter System Interface (ISI) An update and review of specific issues John Cox CEO TETRA MoU Association 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) ISI usage International cross-border cooperation ISI Country A Country B ISI Usage National Multivendor Cooperation ISI Subnetwk B Subnetwk A ISI Usage Local In Country Cooperation ISI User B Network User A Network 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 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 – – Original Plan – reviewed by Member’s Enquiry (ME) Revised Plan – about to re-enter the ME stage – 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 Test Plan Documents ISI and related Test Sessions – 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 www.3countrypilot.com 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 101 448 ETSI Project TETRA – additional ISI specifications • TR 101 448 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 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 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 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 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 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 Packet Mode Data Call across the ISI • IPI (Internetwork Packet Interface) is Packet Data Gateway standard for TETRA • ETSI reference is ETSI TS 101 747 ‘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 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 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 Sources of further information www.tetramou.com www.3countrypilot.com www.etsi.org Thank you John Cox Chief Executive Officer TETRA MoU Association [email protected]