7.1 NAS PCO and ASP definitions

34.123-33GPPPart 3: Abstract test suite (ATS)TSUser Equipment (UE) conformance specification

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

7.1.1 NAS PCO Definitions

Table 7.1.1.1: Dc PCO Type Declarations

PCO Type Declarations
PCO Type	Dc_SAP
Role	LT
Comments	The PCO type for NAS testing

Table 7.1.1.2: Dc PCO Declarations

PCO Declarations
PCO Name	Dc
PCO Type	Dc_SAP
Role	LT
Comments	Carry transmission and reception of NAS messages

7.1.2 Primitives used at Dc PCO

The Dc PCO is used to transmit and receive NAS (MM, CC, SM, SS) messages. Two categories of primitives are operated at the Dc PCO:

– RRC_DataReq for transmission of a NAS PDU;

– RRC_DataInd for reception of a NAS PDU.

These primitives are declared in TTCN tabular form, see Tables 7.1.2.1-1 and 7.1.2.1-2.

Table 7.1.2.1-1: Primitive RRC_DataInd used at the Dc PCO

ASP Name	RRC_DataInd
PCO Type	Dc_SAP
Comments	The ASP is used to indicate the receipt of the NAS PDU message using acknowledged operation (NAS <- RRC).
Parameter Name		Parameter Type	Comments
cellId		INTEGER	Cell Id
rB_Id		SS_RB_Identity	RB identity (RB3 or RB4)
ch		LogicChGERAN	Logical channel (used for interworking with GERAN)
sapId		SapId	RRC SAP identifier (SAP0)
cN_Domain		SS_CN_DomainIdentity	CN domain identity
start		START_Value	Mandatory in INITIAL DIRECT TRANSFER
msg		PDU	NAS PDU
Detailed Comments

Table 7.1.2.1-2: Primitive RRC_DataReq used at the Dc PCO

ASP Name	RRC_DataReq
PCO Type	Dc_SAP
Comments	The ASP is used to request the transmission of the NAS PDU message using acknowledged operation (NAS -> RRC).
Parameter Name		Parameter Type	Comments
cellId		INTEGER	Cell Id
rB_Id		SS_RB_Identity	RB identity (RB3 or RB4)
ch		LogicChGERAN	Logical channel (used for interworking with GERAN)
sapId		SapId	RRC SAP identifier (SAP0)
cN_Domain		SS_CN_DomainIdentity	CN domain identity
msg		PDU	NAS PDU
Detailed Comments

The RB Identity and CN domain parameters defined in the primitives are mandatory for UTRAN and not applicable for GERAN.

The START parameter is mandatory in INITIAL DIRECT TRANSFER; each time when it is received the new START shall be downloaded to the SS to reinitialize counters-C and counters-I.

The LogicChGSM and SapId parameters are mandatory for GERAN and not applicable for UTRAN. They are defined because they may be used for future TTCN test cases.

Except the initial, uplink and downlink direct transfer procedures, the NAS TTCN specification uses the TTCN test steps to realize all RRC functions for testing. The single layer test concept is kept for the NAS tests.

A simple RRC emulation shall be maintained for the NAS tests. It has four functions:

– Emulate the three direct transfer procedures.

– Convert the NAS downlink messages defined in 3GPP TS 24.008 [9] in table format to the NAS message in ASN.1 octet string specified in 3GPP TS 25.331 [21]. Convert the NAS uplink message in the reverse way.

– PER encoding and decoding.

– Have the integrity protection.

RB3 and RB4 are specifically used for the NAS signalling. When an uplink message entered the receiving buffer at AM-SAP from the RLC emulation, either an RRC test step if running will take it out; or the RRC emulation if running will pick the received message from the buffer. Activation of any RRC test steps and activation of any NAS test steps at the same time shall be excluded in TTCN (no concurrency between them).