D2D DEVICE DISCOVERY METHOD AND APPARATUS BASED ON LTE CELLULAR COMMUNICATIONS SYSTEM

• US 20150078466A1
• Filed: 11/21/2014
• Published: 03/19/2015
• Est. Priority Date: 05/23/2012
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Zhou, Han, Feng, Shulan
• Granted Patent: US 9,584,997 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 17/16 Test equipment located at the transmitter
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04W 40/246 Connectivity information discovery
• CPC Class Codes: H04W 56/004 compensating for timing error of reception due to propagation delay
• CPC Class Codes: H04W 76/14 Direct-mode setup
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

This invention is applicable to the field of communications technologies, and provides a device to device (D2D) discovery method and a first D2D user equipment (UE). The method includes: the first D2D UE acquires timing information of the first D2D UE from a Lont Term Evolution (LTE) cellular communications system; receives in a discovery subframe, a device discovery signal from a second D2D UE according to the timing information, wherein the device discovery signal comprises a pilot orthogonal frequency division multiplexing (OFDM) symbol and a device information OFDM symbol; acquires an arrival time of the device discovery signal by performing a time domain correlation of the pilot OFDM symbol of the device discovery signal and a local pilot sequence, acquires device information of the second D2D UE by parsing the device information OFDM symbol of the device discovery. This invention enables a D2D UE to effectively discover other D2D UEs, improves system efficiency, and saves power of the D2D UE.

Claims

1. A discovery method in a device to device (D2D) communications system, the method comprising:

acquiring, by a first D2D user equipment (UE), timing information of the first D2D UE from a Long Term Evolution (LTE) cellular communications system;

receiving, by the first D2D UE in a first discovery subframe, a device discovery signal from a second D2D UE according to the timing information, and the device discovery signal comprises a pilot orthogonal frequency division multiplexing (OFDM) symbol and a device information OFDM symbol; and

acquiring, by the first D2D UE, an arrival time of the device discovery signal sent by the second D2D UE by performing a time domain correlation of the pilot OFDM symbol of the device discovery signal received in the first discovery subframe and a local pilot sequence, and acquiring device information of the second D2D UE by parsing the device information OFDM symbol of the device discovery signal received in the first discovery subframe.

2. The method according to claim 1, wherein:

the first discovery subframe comprises a plurality of OFDM symbols, and each of the OFDM symbols is divided into M frequency resource elements in a frequency domain, wherein M is an integer greater than or equal to 1; and

one or more frequency resource elements of each OFDM symbol serve as a device discovery resource element, and one or more of the device discovery resource elements are selected by each D2D UE as a carrier for a device discovery signal of the each D2D UE.

3. The method according to claim 1, wherein, when the timing information is uplink timing information or downlink timing information, receiving, by the first D2D UE in a first discovery subframe, a device discovery signal from a second D2D UE according to the timing information comprises:

receiving, by the first D2D UE in the first discovery subframe, the device discovery signal from the second D2D UE according to the uplink timing information or the downlink timing information of the first D2D UE.

4. The method according to claim 1, wherein the first discovery subframe comprises a plurality of OFDM symbols, and each of the OFDM symbols comprises a cyclic prefix (CP), and a guard interval (GI) is added to the first discovery subframe, wherein the GI is located between the first discovery subframe and an adjacent paging subframe following the first discovery subframe, and the length of the CP of the first discovery subframe is determined according to the GI.

5. The method according to claim 1, wherein:

the first discovery subframe comprises a plurality of OFDM symbols, and each of the OFDM symbols comprises a cyclic prefix (CP); and

both the first discovery subframe and an adjacent paging subframe following the first discovery subframe use normal CPs or extended CPs.

6. The method according to claim 1, wherein the first discovery subframe comprises a plurality of OFDM symbols, and a frame structure of the first discovery subframe is:

in a plurality of OFDM symbols of the first discovery subframe, at least two OFDM symbols are selected as one group, each group comprises one pilot OFDM symbol and at least one device information OFDM symbol.

7. The method according to claim 6, wherein when the number of OFDM symbols comprised in each group is greater than 2, the pilot OFDM symbol is located in a non-edge location in each group.

8. The method according to claim 6, wherein when the first discovery subframe comprises 14 OFDM symbols, the frame structure of the first discovery subframe

every seven OFDM symbols of the first discovery subframe are divided into one group, and, in each group, any one symbol among the second symbol to the sixth symbol is a pilot OFDM symbol and other six OFDM symbols are device information OFDM symbols.

9. The method according to claim 1, further comprising:

sending, by the first D2D UE, a device discovery signal to the second D2D UE in a second discovery subframe according to the timing information, so that the second D2D UE receives, in the second discovery subframe, the device discovery signal sent by the first D2D UE, performs a time domain correlation of a pilot OFDM symbol of the device discovery signal received in the second discovery subframe and a local pilot sequence, to acquire an arrival time of the device discovery signal sent by the first D2D UE, parses a device information OFDM symbol of the device discovery signal received in the second discovery subframe, to acquire device information of the first D2D UE.

10. The method according to claim 1, further comprising:

calculating, by the first D2D UE, a time at which a signal is sent to the second D2D UE, according to the acquired arrival time of the device discovery signal sent by the second D2D UE and the device information of the second device.

11. A device to device (D2D) user equipment (UE), comprising:

an acquiring unit, configured to acquire timing information of the D2D UE from a Long Term Evolution (LTE) cellular communications system;

a receiver, configured to receive, in a first discovery subframe, a device discovery signal from a second D2D UE according to the timing information, and the device discovery signal comprises a pilot orthogonal frequency division multiplexing (OFDM) symbol and a device information OFDM symbol; and

a discovering unit, configured to;

acquire an arrival time of the device discovery signal sent by the second D2D UE by performing a time domain correlation of the pilot OFDM symbol of the device discovery signal received in the first discovery subframe and a local pilot sequence, and acquire device information of the second D2D UE by parsing the device information OFDM symbol of the device discovery signal received in the first discovery subframe.

12. The D2D UE according to claim 11, wherein:

the first discovery subframe comprises a plurality of OFDM symbols, and each of the OFDM symbols is divided into M frequency resource elements in a frequency domain, wherein M is an integer greater than or equal to 1; and

one or more frequency resource elements of each OFDM symbol serve as a device discovery resource element, and one or more of the device discovery resource elements are selected by each D2D UE as a carrier for a device discovery signal of the each D2D UE.

13. The D2D UE according to claim 11, wherein, when the timing information is uplink timing or downlink timing, the receiver is configured to receive, in the first discovery subframe, the device discovery signal from the second D2D UE according to the uplink timing or the downlink timing of the D2D UE.

14. The D2D UE according to claim 11, wherein the first discovery subframe comprises a plurality of OFDM symbols, and each of the OFDM symbols comprises a cyclic prefix (CP), and a guard interval (GI) is added to the first discovery subframe, wherein the GI is located between the first discovery subframe and an adjacent paging subframe following the first discovery subframe, and the length of the CP of the first discovery subframe is determined according to the GI.

15. The D2D UE according to claim 11, wherein:

the first discovery subframe comprises a plurality of OFDM symbols, and each of the OFDM symbols comprises a cyclic prefix (CP); and

both the first discovery subframe and an adjacent paging subframe following the first discovery subframe use normal CPs or extended CPs.

16. The D2D UE according to claim 11, wherein the first discovery subframe comprises a plurality of OFDM symbols, and a frame structure of the first discovery subframe is:

in a plurality of OFDM symbols of the first discovery subframe, at least two OFDM symbols are selected as one group, each group comprises one pilot OFDM symbol and at least one device information OFDM symbol.

17. The D2D UE according to claim 16, wherein when the number of OFDM symbols comprised in each group is greater than 2, the pilot OFDM symbol is located in a non-edge location in each group.

18. The D2D UE according to claim 16, wherein when the first discovery subframe comprises 14 OFDM symbols, the frame structure of the first discovery subframe is:

every seven OFDM symbols of the first discovery subframe are divided into one group, and, in each group, any one symbol among the second symbol to the sixth symbol is a pilot OFDM symbol and other six OFDM symbols are device information OFDM symbols.

19. The D2D UE according to claim 11, further comprising:

a transmitter, configured to send a device discovery signal to the second D2D UE in a second discovery subframe according to the timing information, so that the second D2D UE receives, in the second discovery subframe, the device discovery signal sent by the D2D UE, performs a time domain correlation of a pilot OFDM symbol of the device discovery signal received in the second discovery subframe and a local pilot sequence, to acquire an arrival time of the device discovery signal sent by the D2D UE, parses a device information OFDM symbol of the device discovery signal received in the second discovery subframe, to acquire device information of the D2D UE.

20. The D2D UE according to claim 19, wherein, when the timing information is uplink timing or downlink timing, the transmitter is configured to send the device discovery signal to the second D2D UE in the second discovery subframe according to the uplink timing or the downlink timing of the D2D UE.