Path section between Uu and PC5

1 . A method implemented in a first user equipment, UE, the method comprising:

sending, over PC5, a direct communication request message, to initiate a link establishment procedure, the direct communication request message comprising: a Uu-status parameter, the Uu-status parameter requesting Uu status information that indicates whether a second UE has an established protocol data unit (PDU) session with a mobile network, the Uu-status parameter indicating a request for communication latency information through the second UE's Uu interface;

receiving, from the second UE, the requested Uu status information; and

using a path selection algorithm to select between a PC5 path and a Uu path to communicate with the second UE, the selection being based on the requested Uu status information.

2 . The method of claim 1 , wherein:

sending the direct communication request message comprising the Uu-status parameter to initiate a layer-2 link establishment procedure.

3 . The method of claim 1 , wherein the Uu-status parameter indicates a request for one or more of:

whether the second UE is able to communicate with a proximity-based service, ProSe, application server;

a path selection policy associated with the second UE;

Uu path availability information from the second UE; and

the second UE's communication capabilities associated with the Uu interface.

4 . The method of claim 1 , wherein the direct communication request message further includes an indication of a path selection policy associated with the first UE.

5 . The method of claim 1 , further comprising one or more of:

as a result of sending the direct communication request message including the Uu-status parameter, receiving, from the second UE, a direction communication accept message including at least one of the requested Uu status information; and

as a result of receiving from the second UE the direction communication accept message including the at least one of the requested Uu status information, using at least one of the at least one requested Uu status information to select one of the PC5 and a Uu path to communicate with the second UE.

6 . The method of claim 5 , further comprising:

when the first UE does not receive the direct communication accept message from the second UE, attempting to communicate with the second UE through the Uu path via a proximity-based service, ProSe, application server.

7 . A method implemented in a first user equipment, UE, the method comprising:

receiving, over PC5, from a second UE, a direct communication request message to initiate a link establishment procedure, the direct communication request message including a Uu-status parameter, the Uu-status parameter requesting Uu status information that indicates whether the first UE has an established protocol data unit (PDU) session with a mobile network, the Uu-status parameter indicating a request for communication latency information through the first UE's Uu interface; and

sending, to the second UE, the requested Uu status information for selection, using a path selection algorithm and the Uu status information, between a PC5 path and a Uu path for communication with the first UE.

8 . The method of claim 7 , wherein:

receiving the direct communication request message comprising the Uu-status parameter from the second UE is to initiate a layer-2 link establishment procedure.

9 . The method of claim 7 , wherein the Uu-status parameter indicates a request for one or more of:

whether the first UE is able to communicate with a proximity-based service, ProSe, application server;

a path selection policy associated with the first UE;

Uu path availability information from the first UE; and

the first UE's communication capabilities associated with the Uu interface.

10 . The method of claim 8 , wherein the direct communication request message further includes an indication of a path selection policy associated with the second UE, the direct communication request message being from the second UE.

11 . The method of claim 9 , further comprising one or more of:

as a result of receiving the direct communication request message including the Uu-status parameter, sending, to the second UE, a direction communication accept message including at least one of the requested Uu status information; and

as a result of receiving the direct communication request message including the Uu-status parameter, negotiating with the second UE to select one of the PC5 and a Uu path to communicate with the second UE.

12 . The method of claim 11 , further comprising:

when the first UE does not send the direct communication accept message to the second UE in response to the received direction communication request message, receiving an attempt to communicate with the first UE through the Uu path via a proximity-based service, ProSe, application server.

13 . A first user equipment, UE, comprising processing circuitry, the processing circuitry configured to cause the first UE to:

send, over PC5, a direct communication request message to initiate a layer-2 link establishment procedure, the direct communication request message including a Uu-status parameter, the Uu-status parameter requesting Uu status information that indicates whether a second UE has an established protocol data unit (PDU) session with a mobile network, the Uu-status parameter indicating a request for communication latency information through the second UE's Uu interface;

receive, from the second UE, the requested Uu status information; and

use a path selection algorithm to select between a PC5 path and a Uu path to communicate with the second UE, the selection being based on the requested Uu status information.

14 . The first UE of claim 13 , wherein:

the processing circuitry is further configured to cause the first UE to send the direct communication request message comprising the Uu-status parameter to initiate a layer-2 link establishment procedure.

15 . The first UE of claim 13 , wherein the Uu-status parameter indicates a request for one or more of:

whether the second UE is able to communicate with a proximity-based service, ProSe, application server;

a path selection policy associated with the second UE;

Uu path availability information from the second UE; and

the second UE's communication capabilities associated with the Uu interface.

16 . The first UE of claim 13 wherein the direct communication request message further includes an indication of a path selection policy associated with the first UE.

17 . The first UE of claim 13 , wherein the processing circuitry is further configured to cause the first UE to one or more of:

as a result of sending the direct communication request message including the Uu-status parameter, receive, from the second UE, a direction communication accept message including at least one of the requested Uu status information; and

as a result of receiving from the second UE the direction communication accept message including the at least one of the requested Uu status information, use at least one of the at least one requested Uu status information to select one of the PC5 and a Uu path to communicate with the second UE.

18 . A first user equipment, UE, comprising processing circuitry, the processing circuitry configured to cause the first UE to:

receive over PC5, from a second UE, a direct communication request message to initiate a link establishment procedure, the direct communication request message including a Uu-status parameter, the Uu-status parameter requesting Uu status information that indicates whether the first UE has an established protocol data unit (PDU) session with a mobile network, the Uu-status parameter indicating a request for communication latency information through the first UE's Uu interface; and

send, to the second UE, the requested Uu status information for selection, using a path selection algorithm and the requested Uu status information, between a PC5 path and a Uu path to communicate with the first UE.

19 . The first UE of claim 18 , wherein:

the processing circuitry is further configured to cause the first UE to receive the direct communication request message comprising the Uu-status parameter from the second UE to initiate a layer-2 link establishment procedure.

20 . The first UE of claim 18 , wherein the Uu-status parameter indicates a request for one or more of:

whether the first UE is able to communicate with a proximity-based service, ProSe, application server;

a path selection policy associated with the first UE;

Uu path availability information from the first UE; and

the first UE's communication capabilities associated with the Uu interface.

21 . The first UE of claim 18 , wherein the direct communication request message further includes an indication of a path selection policy associated with the second UE, the direct communication request message being from the second UE.

22 . The first UE of claim 19 , wherein the processing circuitry is further configured to cause the first UE to one or more of:

as a result of receiving the direct communication request message including the Uu-status parameter, send, to the second UE, a direction communication accept message including at least one of the requested Uu status information; and

as a result of receiving the direct communication request message including the Uu-status parameter, negotiate with the second UE to select one of the PC5 and a Uu path to communicate with the second UE.