Title: CPDLC - Erroneous handling of unexpected QOS

PDR Reference:                                        	98050012
Originator Reference:                           	ATNSI_CPC02 
SARPs Document Reference:                  	CPDLC SARPs, Sections 2.3.5.4.6.1 and 2.3.5.6.6.1
Status:                                            		REJECTED 
PDR Revision Date:                                 	10/06/98 (SUBMITTED -> REJECTED)
PDR Submission Date:                               	12/05/98 
Submitting State/Organization:                     AIRSYS ATM (ACI/ATNSI)
Submitting Author Name:                           	Ilkiewicz, M / Stokes, S.
Submitting Author E-mail Address:          	michel.ilkiewicz@cdv.vly.sextant.thomson.fr 
					Shawn.Stokes@ATNSI.COM 
Submitting Author Supplemental 
Contact Information:                       
SARPs Date:                                        	IV1.1
SARPs Language:                            	English

Summary of Defect:

On receipt of a D-START indication with an unexpected QOS, if the CPDLC-user is active, the CPDLC-ASE invokes the CPDLC-provider-abort indication service primitive.

This is erroneous, because the CPDLC-user cannot be active. Anyway the CPDLC-user does not need to be notified a CPDLC-provider-abort indication, because no CPDLC connection has been set up yet. It should specified that the CPDLC-ASE can only be in the IDLE state. It thus does not need to enter the IDLE state at the end of the exception handling procedure, but just needs to remain in the IDLE state.

Furthermore, the CPDLC-ASE should create an AircraftPDUs APDU or a GroundPDUs APDU with a CPDLCProviderAbortReason [invalid-QOS-parameter] APDU message element and invoke the D-ABORT request service primitive.

Assigned SME:                              		Sub-Volume II SME

Proposed SARPs amendment: 

The requirement in section 2.3.5.4.6.1 should be changed to:

If a D-START indication QOS Priority parameter does not have the abstract value of "high priority flight safety message" or if the QOS Residual Error Rate parameter does not have the abstract value of "low", if the CPDLC-air-ASE is in the IDLE state, the CPDLC-air-ASE shall:

a) create an AircraftPDUs APDU with a CPDLCProviderAbortReason 
[invalid-QOS-parameter] APDU message element,

b) invoke D-ABORT request with:

1) the abstract value "provider" as the D-ABORT Originator 
parameter value, and

2) the APDU as the D-ABORT User Data parameter value, and

c) remain in the IDLE state.

The requirement in section 2.3.5.6.6.1 should be changed to:

If a D-START indication QOS Priority parameter does not have the abstract value of "high priority flight safety message" or if the QOS Residual Error Rate parameter does not have the abstract value of "low", if the CPDLC-ground-ASE is in the IDLE state, the CPDLC-ground-ASE shall:

a) create an GroundPDUs APDU with a CPDLCProviderAbortReason 
[invalid-QOS-parameter] APDU message element,

b) invoke D-ABORT request with:

1) the abstract value "provider" as the D-ABORT Originator 
parameter value, and

2) the APDU as the D-ABORT User Data parameter value, and

c) remain in the IDLE state.

SME Recommendation to CCB:                 

The problem raised in this PDR has been fixed already in PDR 97100026 resolution, items #7 and #8.
However, this resolution has not been correctly applied (see PDR 98050018).

CCB Decision:                                      	atnp_ccb_chair: SUBMITTED (12/05/98)
					atnp_ccb_chair: REJECTED (10/06/98)