Path switching procedure for device-to-device communication

1. A communication device that maintains session continuity, for applications executing in the communication device, in switching from an infrastructure mode communication path to a direct mode communication path, the communication device comprising:

a non-transitory computer readable medium containing program instructions; and

one or more processors, to execute the program instructions to:

determine a public-facing address corresponding to the infrastructure path of the communication device;

replace, for a packet that is to be transmitted over the direct mode communication path to a second communication device, a source address field of the packet with the determined public-facing address;

encapsulate the packet with source and destination address fields corresponding to the communication device and the second communication device, respectively, through the direct mode communication path; and

transmit the encapsulated packet to the direct mode communication path.

2. The communication device of claim 1 , wherein the one or more processors are further to execute the program instructions to:

decapsulate packets received over the direct mode communication path from the second communication device, the decapsulation including replacing destination address fields of the packets with a private address of the communication device in the infrastructure path; and

provide the decapsulated packets to an application layer of the communication device.

3. The communication device of claim 1 , wherein the source address field of the packet that is to be transmitted over the direct mode communication path is initially created by the communication device as an address corresponding to the infrastructure path of the communication device.

4. The communication device of claim 1 , wherein the replaced source address field of the packet includes a public-facing address that refers to a private address of the communication device in the infrastructure path.

5. The communication device of claim 1 , wherein the public-facing address and the source address each include an Internet Protocol (IP) address and a port number.

6. The communication device of claim 1 , wherein the one or more processors, when determining the public-facing address, are further to:

query a Port Control Protocol (PCP) server, a Session Traversal Utilities for Network Address Translation (STUN) server, or a Traversal Using Relays around Network Address Translation (TURN) server.

7. The communication device of claim 1 , wherein the direct mode communication path includes wireless communications based on Institute of Electrical and Electronics Engineers (IEEE) 802.11-based wireless communication standards or based on 3rd Generation Partnership Project (3GPP) standards.

8. The communication device of claim 7 , wherein communications over the infrastructure mode communication path includes communications based on cellular wireless communication standards.

9. A communication device to maintain session continuity, for applications executing in the communication device, in switching from a direct mode communication path to an infrastructure communication path, the communication device including:

a non-transitory computer readable medium containing program instructions; and

one or more processors, to execute the program instructions to:

determine a public-facing address corresponding to the infrastructure path of the communication device;

transmit, over the direct mode communication path and to a second communication device, the public-facing address;

receive, over the infrastructure path, an encapsulated packet from the second communication device;

decapsulate the received encapsulated packet to obtain a packet that includes addressing information corresponding to the direct mode communication path; and

provide the decapsulated packet to an application layer of the communication device.

10. The communication device of claim 9 , wherein the one or more processors are further to execute the program instructions to:

receive, from the second communication device and over the direct mode communication path, a public-facing address corresponding to the infrastructure communication path of the second communication device.

11. The communication device of claim 9 , wherein the one or more processors are further to execute the program instructions to:

encapsulate, by the communication device, packets that are to be delivered to the second communication device, the encapsulation being based on the public-facing address corresponding to the second communication device; and

transmit, by the communication device and over the infrastructure path, the encapsulated packets.

12. The communication device of claim 9 , wherein the public-facing address includes an Internet Protocol (IP) address and a port number.

13. The communication device of claim 9 , wherein when determining the public-facing address, the one or more processors are further to:

query a Port Control Protocol (PCP) server, a Session Traversal Utilities for Network Address Translation (STUN) server, or a Traversal Using Relays around Network Address Translation (TURN) server.

14. The communication device of claim 9 , wherein the direct mode communication path includes wireless communications based on Institute of Electrical and Electronics Engineers (IEEE) 802.11-based wireless communication standards or based on 3rd Generation Partnership Project (3GPP) standards.

15. User equipment (UE) comprising:

a memory to store instructions; and

at least one processor to execute the instructions stored by the memory to:

connect with a second UE, using a communication session formed over an infrastructure path; and

switch communication paths, with the second UE, from the infrastructure path to a direct wireless communication path to the second UE, the switching being performed transparently to an application layer process that is executing at the UE and that is communicating with the second UE, wherein the at least one processor, when switching communication paths is to further execute the instructions stored by the memory to:

replace, for a packet that is to be transmitted over the direct wireless communication path to the second UE, a source address field of the packet with a public-facing address of the UE in the infrastructure path;

encapsulate the packet with source and destination address fields corresponding to the UE and the second UE, respectively, through the direct wireless communication path; and

transmit the encapsulated packet over the direct wireless communication path.

16. The UE of claim 15 , wherein the at least one processor is to further execute the instructions stored by the memory to:

decapsulate packets received over the direct wireless communication path from the second UE, the decapsulation including replacing destination address fields of the packets with a private address of the communication device in the infrastructure path; and

provide the decapsulated packets to an application layer of the communication device.

17. A method for maintaining session continuity, for applications executing in a communication device, in switching from an infrastructure mode communication path to a direct mode communication path, the method comprising:

determining, by the communication device, a public-facing address corresponding to the infrastructure path of the communication device;

replacing, by the communication device and for a packet that is to be transmitted over the direct mode communication path to a second communication device, a source address field of the packet with the determined public-facing address;

encapsulating, by the communication device, the packet with source and destination address fields corresponding to the communication device and the second communication device, respectively, through the direct mode communication path; and

transmitting the encapsulated packet to the direct mode communication path.

18. The method of claim 17 , further comprising:

decapsulating, by the communication device, packets received over the direct mode communication path from the second communication device, the decapsulation including replacing destination address fields of the packets with a private address of the communication device in the infrastructure path; and

providing the decapsulated packets to an application layer of the communication device.

19. The method of claim 17 , wherein the source address field of the packet that is to be transmitted over the direct mode communication path is initially created by the communication device as an address corresponding to the infrastructure path of the communication device.

20. The method of claim 17 , wherein the replaced source address field of the packet includes a public-facing address that refers to a private address of the communication device in the infrastructure path.

21. The method of claim 17 , wherein the public-facing address and the source address each include an Internet Protocol (IP) address and a port number.

22. The method of claim 17 , wherein the determining the public-facing address includes:

querying a Port Control Protocol (PCP) server, a Session Traversal Utilities for Network Address Translation (STUN) server, or a Traversal Using Relays around Network Address Translation (TURN) server.

23. The method of claim 17 , wherein the direct mode communication path includes wireless communications based on Institute of Electrical and Electronics Engineers (IEEE) 802.11-based wireless communication standards or based on 3rd Generation Partnership Project (3GPP) standards.

24. The method of claim 23 , wherein communications over the infrastructure mode communication path includes communications based on cellular wireless communication standards.