Evaluation of practical impacts on Frequency Management for separation of vdl 2 / am-dsb services

Working Group B

San Diego, USA

15-23 January 2001

Presented by EUROCONTROL

In this paper, a first evaluation is made for the ICAO EUR region of the frequency management implications for separating any VDL2 channels by 6 VHF channels from the most adjacent protected AM/DSB frequency service used at airports .

1. Introduction

In the EUROCONTROL’ working paper “VDL mode 2 test results and frequency planning criteria proposal” [3], analysis of the EEC/Bretigny results of interference testing is made and recommendations for VDL 2 frequency planning criteria have been derived .

2. Likely frequency Plan on top of AERONAUTICAL VHF band

Taking into account the recent developments at ICAO FMG EUR for deployment of data-link, and the current frequency protection criteria evaluations , it seems reasonable to assume for the medium/long term the following frequency plan as a likely example :

A provision is made on top of the VHF -band for up to 4 VDL Mode 2 channels that would be progressively deployed; it is assumed that the current ACARS channels would then be replaced by those VDL 2 channels. The proposed separation between those VDL 2 channels is 2 x 25 kHz (1 guard-band channel between them).

Provision is made for one VDL 4 channel (GSC) , with the assumption that the second would be planned at a much distant frequency (this being for VDL 4-robustness purpose considering the certification issues for ADS services). It is also assumed that VDL 4 separation to AM/DSB must be similar to the VDL 2 separation to AM/DSB (6 channels for ground scenarios).
It must be recalled that those VDL services are subject to all be used in a same service volume. From the beginning of the VDL 2 deployment, the CSC will be world-wide dedicated to VDL 2 signalling (and traffic) .
In such case the frequency management constraint to analyse is that only the frequencies lower or equal to 136.625 MHz would be authorised for protected AM/DSB service at airports .

3. Analysis of current frequency allocations above 136.625 MHz.

Based on current ICAO FMG EUR ‘COM 2’ table –version dated 03/01/2001 (a regularly maintained frequency allocation register annexed to EUR Air Navigation Plan), an analysis of the impact on frequency management has been made as follows :

• 
  The European ‘PLANIF’ tool used to perform allocations of aeronautical VHF services has been used to simulate and check feasibility of a complete re-allocation of all current services known beyond 136.625 MHz in the COM 2 table.
  
  
  
• 
  The OPC allocations are IATA non-protected service. Additionally, IATA plans to re-allocate those lower in another IATA sub-band . For these reasons current OPC allocations have not been considered for re-allocation in the simulation.
  
  
  
• 
  The ACC allocations have been given medium priority for re-allocation, as those are exclusively used for aircraft in flight.
  
• 
  Russian allocations have been removed as being outside the ECAC region of concern.
  
• 
  The tool re-allocates in priority the highest frequencies.

  In annex is given a table containing the current allocations beyond 136.625 MHz as introduced for re-assignment simulation in ‘PLANIF’.

  
  
  
  

4. ResulTs of REASSIGNMENT simulaTION

It came out of the simulation that among the 33 services identified to be shifted:

• 
  26 can directly be assigned to another frequency (including 6 implying a shift with a high probability of success).
  

• 
  7 services do not get a re-allocation frequency identified by the tool. Among these 7 services, 5 (ACC or unprotected) are likely not to imply perturbation in the environment considered (airport).
  

• 
  In conclusion, only 2 services, which have no reallocation identified, would need to be further investigated (operational usage, location of the equipment, …).
  

Therefore, this simulation confirms that the re-assignment required by such VDL 2/VDL 4 deployment is feasible.

The details of the simulation have been annexed to this document: first the existing allocations subject to re-assignment are tabled, then the results of PLANIF exercise are listed; those are the re-assignments proposed, and the required additional shifts with candidate frequencies.

5. Reference papers

[2] Meeting report of 8^th working group B meeting of Aeronautical Mobile Communications Panel. Rio de Janeiro, Brasil, 18^th-27^th January 2000.