Content for TS 23.304 Word version: 19.1.0

1… 4… 4.2.3… 4.2.7… 4.3… 5… 5.1.4… 5.1.5… 5.2… 5.3… 5.4… 5.5… 5.6… 5.7 5.8… 5.9… 6… 6.1.2… 6.2… 6.3… 6.3.2… 6.3.2.3… 6.3.2.4… 6.4… 6.4.3… 6.5… 6.5.2… 6.6… 6.7… 6.7.2… 6.8… 7… 7.2…

6.3.2.3 5G ProSe UE-to-Network Relay Discovery 6.3.2.3.1 General 6.3.2.3.2 Procedure for 5G ProSe UE-to-Network Relay Discovery with Model A 6.3.2.3.3 Procedure for 5G ProSe UE-to-Network Relay Discovery with Model B
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6.3.2.3 5G ProSe UE-to-Network Relay Discovery p. 101

6.3.2.3.1 General p. 101

5G ProSe UE-to-Network Relay Discovery is applicable to both 5G ProSe Layer-3 and Layer-2 UE-to-Network relay discovery for public safety use and commercial services. To perform 5G ProSe UE-to-Network Relay Discovery, the 5G ProSe Remote UE and the 5G ProSe UE-to-Network Relay are pre-configured or provisioned with the related information as described in clause 5.1.

In 5G ProSe UE-to-Network Relay Discovery, the UEs use pre-configured or provisioned information for the relay discovery procedures as defined in clause 5.1.4.1.

The Relay Service Code (RSC) is used in the 5G ProSe UE-to-Network Relay discovery, to indicate the connectivity service the 5G ProSe UE-to-Network Relay provides to the 5G ProSe Remote UE. The RSCs (including the dedicated one(s) for emergency service) are configured on the 5G ProSe UE-to-Network Relay and the 5G ProSe Remote UE as defined in clause 5.1.4. The 5G ProSe UE-to-Network Relay and the 5G ProSe Remote UE are aware of whether a RSC is offering 5G ProSe Layer-2 or Layer-3 UE-to-Network Relay service and whether a RSC is for emergency service, based the policy as specified in clause 5.1.4. A 5G ProSe UE-to-Network Relay supporting multiple RSCs can advertise the RSCs using multiple discovery messages, with one RSC per discovery message.

Additional information not directly used for discovery can also be advertised using the PC5-D protocol stack in single or separate discovery messages of type "Relay Discovery Additional Information" as defined in clause 5.8.3.1.

6.3.2.3.2 Procedure for 5G ProSe UE-to-Network Relay Discovery with Model A p. 101

Depicted in Figure 6.3.2.3.2-1 is the procedure for 5G ProSe UE-to-Network Discovery with Model A.

Copy of original 3GPP image for 3GPP TS 23.304, Fig. 6.3.2.3.2-1: 5G ProSe UE-to-Network Relay Discovery with Model A

Figure 6.3.2.3.2-1: 5G ProSe UE-to-Network Relay Discovery with Model A
(⇒ copy of original 3GPP image)

Step 1.

The 5G ProSe UE-to-Network Relay sends a UE-to-Network Relay Discovery Announcement message. The UE-to-Network Relay Discovery Announcement message contains the Type of Discovery Message, Announcer Info and RSC and is sent using the Source Layer-2 ID and Destination Layer-2 ID as described in clause 5.8.3.

For 5G ProSe Layer-3 UE-to-Network Relay, the 5G ProSe Layer-3 UE-to-Network Relay shall only include a RSC in the UE-to-Network Relay Discovery Announcement when the S-NSSAI associated with that RSC belongs to the Allowed NSSAI of the UE-to-Network Relay.

The 5G ProSe Remote UE (1 to 3) determines the Destination Layer-2 ID for signalling reception. The Destination Layer-2 ID is configured with the UE(s) as specified in clause 5.1.4.1.

5G ProSe Remote UE (1 to 3) monitors announcement messages with the 5G ProSe UE-to-Network RSC corresponding to the desired services.

Optionally, the 5G ProSe UE-to-Network Relay may also send Relay Discovery Additional Information messages as defined in clause 6.5.1.3. The parameters contained in this message and the Source Layer-2 ID and Destination Layer-2 ID used for sending and receiving the message are described in clause 5.8.3.

The 5G ProSe Remote UE selects the 5G ProSe UE-to-Network Relay based on the information received in step 1.

6.3.2.3.3 Procedure for 5G ProSe UE-to-Network Relay Discovery with Model B p. 102

Depicted in Figure 6.3.2.3.3-1 is the procedure for 5G ProSe UE-to-Network Relay Discovery with Model B.

Copy of original 3GPP image for 3GPP TS 23.304, Fig. 6.3.2.3.3-1: 5G ProSe UE-to-Network Relay Discovery with Model B

Figure 6.3.2.3.3-1: 5G ProSe UE-to-Network Relay Discovery with Model B
(⇒ copy of original 3GPP image)

Step 1.

The 5G ProSe Remote UE sends a 5G ProSe UE-to-Network Relay Discovery Solicitation message. The 5G ProSe UE-to-Network Discovery Solicitation message contains the Type of Discovery Message, Discoverer Info, RSC and optionally Target Info and is send using the Source Layer-2 ID and Destination Layer-2 ID as described in clause 5.8.3. The 5G ProSe Remote UE discovering a 5G ProSe UE-to-Network Relay sends a solicitation message with the RSC which is associated to the desired connectivity service. The RSC is based on the Policy/Parameters specified in clause 5.1.4.1.

How the 5G ProSe UE-to-Network Relays (1 to 3) determine the Destination Layer-2 ID for signalling reception is specified in clause 5.8.3. The Destination Layer-2 ID is configured with the UE(s) as specified in clause 5.1.4.1.

Step 2.

If the RSC contained in the solicitation message matches any of the (pre)configured RSC(s), as specified in clause 5.1.4.1, of a 5G ProSe UE-to-Network Relay, and the Target Info contained in the solicitation message, if any, matches the 5G ProSe UE-to-Network Relay, the 5G ProSe UE-to-Network Relays (e.g. 1 and 2) respond to the 5G ProSe Remote UE with a UE-to-Network Relay Discovery Response message. The 5G ProSe UE-to-Network Relay Discovery Response message contains the Type of Discovery Message, Discoveree Info and RSC and is sent using the Source Layer-2 ID and Destination Layer-2 ID as described in clause 5.8.3.

For 5G ProSe Layer-3 UE-to-Network Relay, the 5G ProSe UE-to-Network Relay shall only respond to a matching RSC in the UE-to-Network Relay Discovery Solicitation message when the S-NSSAI associated with that RSC belongs to the Allowed NSSAI of the 5G ProSe UE-to-Network Relay.

The 5G ProSe Remote UE selects the 5G ProSe UE-to-Network Relay based on the information received in step 2.