PAGE CONTENTS
Objectives
Within the framework of the Iris programme, the development of end-user satellite equipment on the ground and on-board aircraft will be undertaken. This will require the development of test beds for interoperability testing including functionalities not covered by the satellite communication standard.
In this context, one identified activity is the development of the Mobility Testing Environment (MTE) for the ATM safety communications in order to test the performance of the Air-Ground Router (AGR). The AGR is being produced within a separate ESA funded task and is based on internet protocol suite version 6 (IPv6). AGR is placed at the boundary of the ground network infrastructure of the European Air Traffic Management Network (EATMN). It offers an interface with the Ground Earth Station (GES) of the new satellite communication (SATCOM) sub-network.
As such, the MTE will be realised as a set of SW and HW elements with external IP interface to the AGR (therefore, physically decoupled from the AGR). Therefore, the MTE will allow the verification of the functionality of AGRs from different vendors.
The main objective of the present project is the design and development of a Mobility Testing Environment (MTE) for validation and verification of Air-Ground Router (AGR).
The MTE shall allow the testing of any commercially available AGR along with the customized solution developed under separate ESA contract that comprises an AGR as well as functional enhancements to the AGR called Routing Enhancements for Iris Link (REIL).
It is expected that some parts of MTE may in future be upgraded and used within appropriate ANTARES verification platforms.
Challenges
One key issue in the MTE project will be testing options for extending the period of an interruption-free IP connectivity between moving aircraft and the ATC/AOC ground-based units.
Due to the assumed topology where each GES is served by its dedicated AGR, when the AES moves between GESs, this automatically means changing the L3 point of attachment for the MN(s) served by this AES. Therefore, L2 handover between GESs will trigger L3 handover between associated AGRs. After a break-before-make L2 handover has been initiated, a given MN within the concerned aircraft will be no longer reachable for the ground CNs under its old IP (CoA) address. It may take significant time until MN has configured its new CoA and performed successful registration at HA. Without specific measures taken, this may cause that existing transport sessions between CNs and this MN will break and will have to be re-established when the new CoA becomes registered. MTE shall enable investigating the efficiency of supplementary mechanisms for avoiding connectivity loss during handovers.
Similarly, MTE shall allow for validating supplementary enhancements to the GES switchover in case of primary GES failure, including these for GES status monitoring and implicitly signalling the GES failure to GGR.
Plan
The project plan comprises 3 tasks as described below:
- Task 1: Specification of the test framework technical requirements
The main objective of this task is to capture the technical functional requirements necessary for the development of the MTE. The requirements will be based on ICAO Doc 9896, as well as relevant deliverables of ARTES 10(Iris) and ARTES 1.
ICAO Document 9896 specifies the standards for the Aeronautical telecommunication network based on IPv6. IETF RFCs deliver the detailed standards for IPv6 protocol suite including mobility management. However, existing RFCs put no particular focus on satellite based communication and are even less concerned with safety-critical ATS services, therefore another objective of this task is to merge and harmonize requirements specified by ICAO and IETF.
The outputs of task 1 are the Technical Requirements Document (TRD) and Test Plan Document (TPD) that serve as inputs to task 2.
- Task 2: Development of the test framework
The objective of this task is to define the SW and HW architecture of the MTE and develop the MTE framework based on the TRD along with related test/validation scenarios defined in TPD. The task comprises development, integration and configuration of all required software modules on LINUX-based PCs.
Task 2 provides the Software/Hardware Architecture Document (SHAD) as an input to task 3.
- Task 3: Validation of the mobility test framework
The main objective of this task is the validation of the MTE test framework according to scenarios defined in TPD. Validation will span all components being produced or purchased under MTE task (MN, GGR, HA, CN).
TPD and SHAD are inputs to task 3 that will actually produce the MTE and associated documentation: Validation Results Document (VRD) and User Manual (UM), including detailed configuration and installation information. This task will also provide all MTE hardware and software.
Current Status
From the beginning of the MTE project onwards, a full set of deliverables has been produced, reviewed and accepted by ESA:
- Technical Requirements Document (TRD)
- Test Plan Document (TPD)
- Software/Hardware Architecture Document (SHAD)
MTE hardware has been configured, required software installed, and required features implemented, followed by the validation activities. Recently, MTE validation – checking the compliance of the MTE implementation with TRD – has been successfully closed. In the course of MTE validation further two deliverables have been produced, reviewed and accepted:
- Validation Results Document (VRD)
- User Manual (UM)
Current MTE implementation allows for emulating the SATCOM UT with two radio units (supporting two independent channels between the UT and two different GESs).
The MTE project is completed.
The MTE hardware/software will remain available for subsequent functional enhancements and testing, e.g. for integrated end-to-end tests with real AGR(s). Such tests could significantly contribute to the optimization of various IPv6/MIPv6 adjustable parameters within the challenging SATCOM context.