Systems, methods, and devices for synchronization source selection for device-to-device communication

Patent metadata

Field	Value
Publication number	US-10813068-B2
Application number	US-201414582580-A
Country	US
Kind code	B2
Filing date	Dec 24, 2014
Priority date	May 8, 2014
Publication date	Oct 20, 2020
Grant date	Oct 20, 2020

Abstract

A user equipment (UE) is configured to scan for device-to-device synchronization sources based on scanning configuration information. The UE is configured to report detection of a device-to-device synchronization source to an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (eNB) in response to determining that the device-to-device synchronization source meets one or more reporting requirements of the scanning configuration information. The UE is configured to receive a communication from the eNB enabling the UE as a synchronization source and transmit signals to provide a synchronization reference to one or more in-range UEs including the device-to-device synchronization source.

First claim

The invention claimed is:

1. An apparatus for use in user equipment (UE), comprising:
measurement logic, at least a portion of which comprises circuitry, to determine a reference signal received power (RSRP) measurement of a signal received from a cell of an evolved universal terrestrial radio access network (E-UTRAN); and
processing logic, at least a portion of which comprises circuitry, to:
determine that the UE is in coverage of the cell of the E-UTRAN based on the RSRP; and
configure the UE to transmit a direct link synchronization signal (SS) using a PC5 interface for discovery or communication in either a radio resource configuration (RRC) connected state or an RRC idle state, wherein to configure the UE, the processing logic is configured to:
decode a system information block (SIB) message from the E-UTRAN to determine a signal strength threshold for determining whether to generate the direct link SS, the signal strength threshold being between −115 dbM and −60 dbM;
compare the RSRP measurement to the signal strength threshold; and
in response to a determination that the RSRP measurement is below the signal strength threshold, generate synchronization information for the direct link SS for transmission using the PC5 interface.

2. The apparatus of claim 1 , wherein to configure the UE to transmit the direct link SS, the processing logic is configured to autonomously activate the UE as a synchronization source without being configured by dedicated signaling from the E-UTRAN to transmit synchronization information.

3. The apparatus of claim 2 , wherein to autonomously activate the UE as a synchronization source, the processing logic is to configure the UE to periodically transmit at least one of the direct link SS and a direct link information message.

4. The apparatus of claim 1 , wherein the processing logic is configured to derive synchronization information for the direct link SS from information or signals received from at least one of the E-UTRAN and a peer UE acting as a synchronization reference.

5. The apparatus of claim 1 , wherein the processing logic is further to:
determine that the UE is in coverage on a frequency used for direct link discovery; and
configure the UE to transmit the direct link SS in a subframe on the frequency used for direct link discovery.

6. The apparatus of claim 5 , wherein the processing logic is further to:
generate a direct link information message comprising configuration parameters for direct link communication; and
configure the UE to transmit the direct link information message on the frequency used for direct link discovery in the same subframe as the direct link SS.

7. The apparatus of claim 5 , wherein the processing logic is further to select the subframe based on a determination that the subframe is not used by the UE for uplink transmission.

8. The apparatus of claim 1 , wherein the processing logic is further to:
determine that the UE is in coverage on a frequency used for direct link communication;
configure the UE to transmit the direct link SS in a subframe on the frequency used for direct link communication;
generate a direct link information message comprising configuration parameters for direct link communication; and
configure the UE to transmit the direct link information message on the frequency used for direct link communication in the same subframe as the direct link SS.

9. The apparatus of claim 8 , wherein the processing logic is further to select the subframe within the same time period in which the UE is configured to transmit direct link control information.

10. An apparatus for use in user equipment (UE), comprising:
a transceiver to communicate with an evolved universal terrestrial radio access network (E-UTRAN) node B (eNB); and
one or more processors coupled to the transceiver to:
perform a cell search and synchronize with a serving eNB, wherein the UE is configured to camp on a serving cell corresponding to the serving eNB and to receive, from the serving eNB through the transceiver, a threshold value for determining whether to generate the direct link synchronization information, the threshold value being between −115 dbM and −60 dbM;
derive direct link synchronization information from one or more of a system information message and a dedicated direct link configuration information message received through the transceiver from the serving eNB;
configure the UE to transmit, through the transceiver, the direct link synchronization information in a synchronization reference signal to one or more direct communication UEs that are out-of-coverage of the serving eNB in response to any of at least two trigger conditions comprising:
a network based trigger condition wherein the UE is in a radio resource configuration (RRC) connected state, the UE is in coverage of the cell of the E-UTRAN, and is configured to transmit the direct link synchronization information by dedicated signaling from the serving eNB; and
a UE based trigger condition wherein the UE is in either an RRC connected state or an RRC idle state, and wherein a reference signal received power (RSRP) of the serving eNB is below the threshold value, the second trigger condition causing the UE to generate the direct link synchronization information.

11. The apparatus of claim 10 , wherein the direct link synchronization information is included in the system information message, wherein the direct link synchronization information comprises information regarding resources available for direct link synchronization information transmission, direct link synchronization information reception, and the threshold value, wherein the one or more processors configure the UE to transmit the direct link synchronization information in the resources used for direct link synchronization information transmission in response to any one of the at least two trigger conditions.

12. The apparatus of claim 10 , wherein the one or more processors are further configured to generate one or more measurement reports based on reporting criteria configured by the serving eNB.

13. The apparatus of claim 12 , wherein the UE is further configured to perform measurements for evaluating the reporting criteria based on scanning configuration information.

14. The apparatus of claim 12 , wherein the one or more measurement reports comprise one or more of:
an identity of the one or more direct communication UEs that sent the direct link synchronization signal,
a stratum level of the one or more direct communication UEs that sent the direct link synchronization signal, and
a signal strength of the direct link synchronization signal.

15. The apparatus of claim 10 , wherein to generate the direct link synchronization information to provide a synchronization reference is in response to a direct link data communication trigger by an upper layer of the UE.

16. The apparatus of claim 10 , wherein the one or more processors further configure the UE to transmit the direct link synchronization information to provide the synchronization reference by transmission of at least one of a direct link synchronization and a direct link information message comprising configuration parameters for direct link communication.

17. A non-transitory machine readable storage medium including machine-readable instructions, when executed by one or more processors of a first user equipment (UE), to:
derive synchronization information from information or signals received from at least one of an evolved universal terrestrial radio access network (E-UTRAN) and a second UE acting as a synchroniz

Assignees

• Apple Inc

Inventors

• He Hong
• Khoryaev Alexey
• Chatterjee Debdeep
• Shilov Mikhail
• Zong Pingping

Classifications

• H04W56/0015

  one node acting as a reference for the others · CPC title

• H04W24/10 Primary

  Scheduling measurement reports {; Arrangements for measurement reports} · CPC title

• H04W56/0025 Primary

  synchronizing potentially movable access points · CPC title

• H04W48/16

  Discovering, processing access restriction or access information · CPC title

• H04W8/005

  Discovery of network devices, e.g. terminals · CPC title