METHOD AND APPARATUS FOR TRANSMITTING DEVICE-TO-DEVICE (D2D) SYNCHRONIZATION SIGNALS

• US 20160330702A1
• Filed: 05/02/2016
• Published: 11/10/2016
• Est. Priority Date: 05/04/2015
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: SORRENTINO, Stefano
• Granted Patent: US 10,075,930 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/0025 synchronizing potentially movable access points
• CPC Class Codes: H04W 76/14 Direct-mode setup
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals

Abstract

A method and apparatus in a first User Equipment (UE) that reduces the number of required transmissions when transmitting device-to-device (D2D) synchronization signals or broadcast channels in a wireless network. The first UE determines its level of interest in being received by a second UE that is within network coverage, and adapts a time pattern for transmission of synchronization signals or broadcast channels, depending on the determined level of interest of the first UE. The first UE'"'"'s interest may be determined by analyzing a type of service that the first UE is interested in performing, and concluding the first UE is interested in being received by the second UE only when the first UE is interested in performing a certain type of service.

Claims

1. A method in a first User Equipment (UE) for transmitting device-to-device (D2D) synchronization signals or broadcast channels in a wireless network, said method comprising:

determining, at the first UE, the first UE'"'"'s level of interest in being received only by a second UE that is within network coverage; and

adapting, at the first UE, a time pattern for transmission of synchronization signals or broadcast channels, depending on the determined level of interest of the first UE.

2. A method in a User Equipment (UE) for transmitting device-to-device (D2D) synchronization signals or broadcast channels, said method comprising:

determining, at the UE, the UE'"'"'s level of interest in being received by a second UE that uses the same or a different synchronization reference; and

adapting, at the UE, a time pattern for transmission of synchronization signals or broadcast channels, depending on the determined level of interest of the UE.

3. The method as recited in claim 2, wherein determining the first UE'"'"'s level of interest includes:

analyzing a type of service that the first UE is interested in performing; and

concluding the first UE is interested in being received by the second UE only when the first UE is interested in performing a certain type of service.

4. The method as recited in claim 3, wherein determining the first UE'"'"'s level of interest also includes:

determining whether the second UE is compatible with the certain type of service; and

concluding the first UE is interested in being received by the second UE only when the second UE is compatible with the certain type of service.

5. The method as recited in claim 3, wherein the first UE is outside network coverage, and the step of determining the first UE'"'"'s level of interest includes determining whether the first UE is interested in performing commercial discovery or Public Safety discovery, wherein the time pattern for transmission of synchronization signals or broadcast channels is different for commercial discovery and Public Safety discovery;

and

wherein the step of adapting the time pattern for transmission includes selecting an appropriate time pattern based on the determination of whether the first UE is interested in performing commercial discovery or Public Safety discovery.

6. The method as recited in claim 2, wherein determining the first UE'"'"'s level of interest includes:

determining whether the second UE is inside a coverage area of an eNodeB;

when the second UE is inside the coverage area of the eNodeB, determining whether the second UE is capable of relaying a synchronization reference that originated from the eNodeB; and

when the second UE is capable of relaying the synchronization reference that originated from the eNodeB, determining the first UE is interested when the first UE desires to synchronize with the eNodeB.

7. The method as recited in claim 2, wherein when the second UE uses the same synchronization reference, adapting the time pattern includes performing one of:

transmitting synchronization signals or broadcast channels only at a time coinciding with a discovery resource pool;

or

refraining from transmitting any synchronization signals or broadcast channels.

8. The method as recited in claim 2, wherein when the second UE uses a different synchronization reference and is outside a coverage area of an eNodeB, adapting the time pattern includes periodically transmitting synchronization signals or broadcast channels only during a device-to-device (D2D) interval or until the first UE changes its relay preference.

9. The method as recited in claim 2, wherein when the second UE uses a different synchronization reference and is inside a coverage area of an eNodeB, adapting the time pattern includes:

receiving a synchronization reference signal from the second UE;

determining whether the synchronization reference signal originated from the eNodeB;

when the synchronization reference signal originated from the eNodeB, preforming one of;

transmitting synchronization signals or broadcast channels only at a time coinciding with a discovery resource pool;

or

refraining from transmitting any synchronization signals or broadcast channels; and

when the synchronization reference signal did not originate from the eNodeB, periodically transmitting synchronization signals or broadcast channels.

10. An apparatus in a first User Equipment (UE) for transmitting device-to-device (D2D) synchronization signals or broadcast channels in a wireless network, said apparatus comprising:

a transceiver; and

a processor coupled to a non-transitory memory that stores computer program instructions, wherein when the processor executes the instructions, the processor controls;

an interest determining circuit configured to determine the first UE'"'"'s level of interest in being received by a second UE that uses the same or a different synchronization reference; and

a transmission time pattern adapting circuit configured to adapt a time pattern for transmission of synchronization signals or broadcast channels, depending on the determined level of interest of the first UE.

11. The apparatus as recited in claim 10, wherein the interest determining circuit is configured to determine the first UE'"'"'s level of interest by:

analyzing a type of service that the first UE is interested in performing; and

concluding the first UE is interested in being received by the second UE only when the first UE is interested in performing a certain type of service.

12. The apparatus as recited in claim 11, wherein the interest determining circuit also determines the first UE'"'"'s level of interest by:

determining whether the second UE is compatible with the certain type of service; and

concluding the first UE is interested in being received by the second UE only when the second UE is compatible with the certain type of service.

13. The apparatus as recited in claim 11, wherein the first UE is outside network coverage and the interest determining circuit is configured to determine whether the first UE is interested in performing commercial discovery or Public Safety discovery, wherein the time pattern for transmission of synchronization signals or broadcast channels is different for commercial discovery and Public Safety discovery;

and

wherein the transmission time pattern adapting circuit is configured to adapt the time pattern for transmission by selecting an appropriate time pattern based on the determination of whether the first UE is interested in performing commercial discovery or Public Safety discovery.

14. The apparatus as recited in claim 10, wherein the interest determining circuit is configured to determine the first UE'"'"'s level of interest by:

determining whether the second UE is inside a coverage area of an eNodeB;

when the second UE is inside the coverage area of the eNodeB, determining whether the second UE is capable of relaying a synchronization reference that originated from the eNodeB; and

when the second UE is capable of relaying the synchronization reference that originated from the eNodeB, determining the first UE is interested when the first UE desires to synchronize with the eNodeB.

15. The apparatus as recited in claim 10, wherein when the second UE uses the same synchronization reference, the transmission time pattern adapting circuit is configured to adapt the time pattern by controlling a UE transceiver to perform one of:

transmitting synchronization signals or broadcast channels only at a time coinciding with a discovery resource pool;

or

refraining from transmitting any synchronization signals or broadcast channels.

16. The apparatus as recited in claim 10, wherein when the second UE uses a different synchronization reference and is outside a coverage area of an eNodeB, the transmission time pattern adapting circuit is configured to adapt the time pattern by controlling a UE transceiver to periodically transmit synchronization signals or broadcast channels only during a device-to-device (D2D) interval or until the first UE changes its relay preference.

17. The apparatus as recited in claim 10, wherein when the second UE uses a different synchronization reference and is inside a coverage area of an eNodeB and a synchronization reference signal is received from the second UE, the transmission time pattern adapting circuit is configured to adapt the time pattern by:

determining whether the synchronization reference signal originated from the eNodeB;

when the synchronization reference signal originated from the eNodeB, preforming one of;

transmitting synchronization signals or broadcast channels only at a time coinciding with a discovery resource pool;

or

refraining from transmitting any synchronization signals or broadcast channels; and

when the synchronization reference signal did not originate from the eNodeB, periodically transmitting synchronization signals or broadcast channels.

18. A system for adapting a first User Equipment'"'"'s transmission time pattern for transmitting device-to-device (D2D) synchronization signals or broadcast channels in a wireless communication network, wherein the first User Equipment (UE) is operating outside a coverage area of an eNodeB in the wireless communication network, said system comprising:

an apparatus in the first UE, comprising;

a processor that executes computer program instructions stored in a non-transitory memory;

an interest determining circuit controlled by the processor and configured to determine the first UE'"'"'s level of interest in being received by a second UE that uses the same or a different synchronization reference; and

a transmission time pattern adapting circuit controlled by the processor and configured to adapt a time pattern for transmission of synchronization signals or broadcast channels, depending on the determined level of interest of the first UE; and

the second UE that provides a relay to the eNodeB.

19. The system as recited in claim 18, wherein the interest determining circuit is configured to determine the first UE'"'"'s level of interest by:

analyzing a type of service that the first UE is interested in performing; and

concluding the UE is interested in being received by the second UE only when the first UE is interested in performing a certain type of service.

20. The system as recited in claim 19, wherein the interest determining circuit also determines the first UE'"'"'s level of interest by:

receiving from the second UE, information regarding capabilities of the second UE and whether the second UE is operating inside or outside the coverage area of the eNodeB;

determining whether the second UE is capable of relaying information for the certain type of service; and

concluding the first UE is interested in being received by the second UE only when the second UE is capable of relaying information for the certain type of service.

21. The system as recited in claim 20, wherein the interest determining circuit is configured to determine the first UE'"'"'s level of interest by:

determining whether the second UE is inside the coverage area of the eNodeB by analyzing the information received from the second UE regarding whether the second UE is operating inside or outside the coverage area of the eNodeB;

when the second UE is inside the coverage area of the eNodeB, determining whether the second UE is capable of relaying a synchronization reference that originated from the eNodeB; and

when the second UE is capable of relaying the synchronization reference that originated from the eNodeB, determining the first UE is interested when the first UE desires to synchronize with the eNodeB.

22. The system as recited in claim 19, wherein the first UE is outside network coverage and the interest determining circuit is configured to determine whether the first UE is interested in performing commercial discovery or Public Safety discovery, wherein the time pattern for transmission of synchronization signals or broadcast channels is different for commercial discovery and Public Safety discovery;

and

wherein the transmission time pattern adapting circuit is configured to adapt the time pattern for transmission by selecting an appropriate time pattern based on the determination of whether the first UE is interested in performing commercial discovery or Public Safety discovery.

23. The system as recited in claim 18, wherein when the second UE uses the same synchronization reference, the transmission time pattern adapting circuit is configured to adapt the time pattern by controlling a transceiver of the first UE to perform one of:

transmitting synchronization signals or broadcast channels only at a time coinciding with a discovery resource pool;

or

refraining from transmitting any synchronization signals or broadcast channels.

24. The system as recited in claim 18, wherein when the second UE uses a different synchronization reference and is outside the coverage area of the eNodeB, the transmission time pattern adapting circuit is configured to adapt the time pattern by controlling a transceiver of the first UE to periodically transmit synchronization signals or broadcast channels only during a device-to-device (D2D) interval or until the first UE changes its relay preference.

25. The system as recited in claim 18, wherein when the second UE uses a different synchronization reference and is inside the coverage area of the eNodeB and the first UE receives a synchronization reference signal from the second UE, the transmission time pattern adapting circuit is configured to adapt the time pattern by:

determining whether the synchronization reference signal originated from the eNodeB;

when the synchronization reference signal originated from the eNodeB, preforming one of;

transmitting synchronization signals or broadcast channels only at a time coinciding with a discovery resource pool;

or

refraining from transmitting any synchronization signals or broadcast channels; and

when the synchronization reference signal did not originate from the eNodeB, periodically transmitting synchronization signals or broadcast channels.