Handover of device-to-device (D2D) user equipment (UE) devices using D2D subframes with cell identifiers

• US 9,992,783 B2
• Filed: 12/18/2014
• Issued: 06/05/2018
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Kalhan, Amit, Chang, Henry
• Primary Examiner(s): Han, Clemence
• Application Number:
  US15/105,536
• Publication Number:
  US 20160330781A1
• Time in Patent Office: 1,265 Days
• CPC Class Codes: H04L 67/104 Peer-to-peer [P2P] networks
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/0061 of neighbour cell information
• CPC Class Codes: H04W 36/305 Handover due to radio link failure control signalling for hand-off failure H04W36/0079
• CPC Class Codes: H04W 36/36 by user or terminal equipment
• CPC Class Codes: H04W 4/08 User group management
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 48/14 using user query or user detection
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/1215 for collaboration of different radio technologies
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: H04W 72/56 based on priority criteria
• CPC Class Codes: H04W 76/14 Direct-mode setup
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A Device-to-device (D2D) user equipment (UE) device communicating with another D2D UE device within a first cell transmits a D2D subframe that includes a cell identifier a second cell when the UE device moves from the first cell to the second cell. After a handover to the second cell is initiated, the D2D UE device can suspend D2D communication. The D2D UE device transmits the D2D subframe, such as D2D discovery subframe, identifying the second cell when the handover is complete. The other D2D UE device identifies the second cell to the base station providing the first cell. The base stations providing the first cell and the second cell coordinate to determine resources for D2D communication between the D2D UE devices.

Claims

1. A method performed at a device-to-device (D2D) user equipment (UE) device, the method comprising:

communicating with another D2D UE device using D2D communication while the D2D UE device and the another D2D UE device are located within a first cell provided by a first base station;

transmitting a D2D subframe to the another D2D UE device after a handover from the first cell to a second cell is complete, the D2D subframe conveying a cell identifier identifying the second cell;

transmitting a D2D request to a second base station providing the second cell;

receiving, from the second base station, communication resource information identifying D2D communication resources; and

continuing D2D communication with the another D2D UE device using the D2D communication resources.

2. The method of claim 1, further comprising:

after the handover is initiated, transmitting a message with the cell identifier and a frequency of the second cell.

3. The method of claim 2, wherein reception at the another D2D UE device of the message with the cell identifier and frequency triggers a timer at the another D2D UE device, wherein if the timer is stopped before expiration, the another D2D UE device monitors for discovery signal in accordance with the frequency indicated in the message.

4. The method of claim 1 further comprising:

suspending D2D communication after the handover is initiated.

5. The method of claim 1, wherein transmitting the D2D subframe comprises transmitting a D2D discovery subframe to the another D2D UE device in response to completion of the handover independent of a status of a discovery signal buffer at the D2D UE device.

6. The method of claim 1, wherein the handover is triggered by a measurement report sent by the D2D UE device.

7. The method of claim 1, wherein the D2D subframe includes a D2D message comprising the cell identifier.

8. The method of claim 1, wherein a scrambling sequence for scrambling a reference signal of the D2D subframe is a function of the cell identifier.

9. A method performed at a first device-to-device (D2D) user equipment (UE) device, the method comprising:

communicating with a second D2D UE device using D2D communication while the first D2D UE device and the second D2D UE device are located within a first cell provided by a first base station;

receiving a D2D subframe from the second D2D UE device after a handover of the second D2D UE device to a second cell is complete, the D2D subframe conveying a cell identifier identifying the second cell;

transmitting a cell ID update message including the cell identifier to the first base station;

receiving, from the first base station, communication resource information identifying D2D communication resources; and

continuing D2D communication with the second D2D UE device using the D2D communication resources.

10. The method of claim 9, further comprising:

after the handover is initiated, receiving a message with the cell identifier and a frequency of the second cell; and

monitoring a channel for the discovery signal in accordance with the frequency.

11. The method of claim 10, further comprising:

initiating a timer in response to receiving the message with the cell identifier and frequency at the first D2D UE device; and

monitoring, at the first D2D UE device, the channel for the discovery signal in accordance with the frequency only if the timer is stopped before expiration of the timer.

12. The method of claim 9 further comprising:

suspending D2D communication after the handover is initiated.

13. The method of claim 9, wherein the handover is triggered by a measurement report sent by the second D2D UE device.

14. The method of claim 9, wherein the D2D subframe includes a D2D message comprising the cell identifier.

15. The method of claim 9, wherein a scrambling sequence for scrambling a reference signal of the D2D subframe is a function of the cell identifier.

16. A method comprising:

providing a first cell for communication from a first base station;

providing a second cell for communication from a second base station, a first user equipment (UE) device and a second UE device communicating over a device-to device (D2D) communication link within the first cell;

receiving, at the first base station, a measurement report from the second UE device to trigger a handover of the second UE device from the first base station to the second base station;

after the handover is complete, receiving, at the second base station from the second UE device, a request for D2D resources;

receiving, at the first base station from the first UE device, a cell identifier identifying the second cell as the serving cell of the second UE device;

coordinating between the first base station and the second base station to identify common D2D resources for D2D communication between the first UE device and the second UE device; and

transmitting communication resource information from the first base station to the first UE device and from the second base station to the second UE device, the communication resource information identifying the common D2D resources.

17. The method of claim 16, wherein the cell identifier is received at the first UE device from the second UE device in a D2D subframe.

18. The method of claim 17, wherein the cell identifier is received at the first UE device from the second UE device in a D2D discovery signal.

19. The method of claim 16, wherein the base stations and UE devices operate in accordance with at least one release of The Third-Generation Partnership Project Long-Term Evolution (3GPP LTE) communication specification.

20. A device-to-device (D2D) user equipment (UE) device comprising:

a transceiver configured to exchange D2D signals from another D2D UE device using D2D communication while the D2D UE device and the another D2D UE device are located within a first cell provided by a first base station,

the transceiver comprising a transmitter and a receiver, the transmitter configured to;

transmit a D2D subframe to the another D2D UE device after a handover of the D2D UE device from the first cell to a second cell is complete, the D2D subframe conveying a cell identifier identifying the second cell and to transmit a D2D request to a second base station providing the second cell;

the receiver configured to receive, from the second base station, communication resource information identifying D2D communication resources, the transceiver configured to resume D2D communication with the another D2D UE device using the D2D communication resources.

21. The D2D UE device of claim 20, wherein the D2D subframe includes a D2D message comprising the cell identifier.

22. The D2D UE device of claim 20, wherein a scrambling sequence for scrambling a reference signal of the D2D subframe is a function of the cell identifier.