Cell detection in a cellular communications network

Patent metadata

Field	Value
Publication number	US-2016227462-A1
Application number	US-201514694620-A
Country	US
Kind code	A1
Filing date	Apr 23, 2015
Priority date	Jan 30, 2015
Publication date	Aug 4, 2016
Grant date	—

Abstract

Systems and methods relating to cell detection are disclosed. In some embodiments, systems and methods are disclosed for performing cell detection while suppressing interference from either a current serving cell or a previous serving cell of a wireless device depending on whether the wireless device is approaching the current serving cell or leaving the current serving cell. In this manner, cell detection is improved in a manner that is particularly suitable for, e.g., high speed train scenarios, but the systems and methods disclosed herein are not limited thereto.

First claim

1 . A method of operation of a wireless device comprising:
determining whether the wireless device is moving toward a current serving cell of the wireless device or away from the current serving cell of the wireless device; if the wireless device is moving toward the current serving cell, initiating suppression of transmissions from a previous serving cell of the wireless device during detection of a predetermined signal from another cell; and if the wireless device is moving away from the current serving cell, initiating suppression of transmissions from the current serving cell of the wireless device during detection of a predetermined signal from another cell.

2 . The method of claim 1 wherein:
initiating suppression of transmissions from the previous serving cell of the wireless device during detection of the predetermined signal from another cell comprises initiating suppression of transmissions from a perceived direction of the previous serving cell of the wireless device during detection of the predetermined signal from another cell; and
initiating suppression of transmissions from the current serving cell of the wireless device during detection of the predetermined signal from another cell comprises initiating suppression of transmissions from a perceived direction of the current serving cell of the wireless device during detection of the predetermined signal from another cell.

3 . The method of claim 2 wherein the predetermined signal is one of a group consisting of: a synchronization signal, a discovery signal, a reservation signal, and a reference signal.

4 . The method of claim 1 wherein determining whether the wireless device is moving toward the current serving cell of the wireless device or away from the current serving cell of the wireless device comprises determining a direction of movement of the wireless device relative to the current serving cell of the wireless device based on at least one of a group consisting of:
a measured time drift of the current serving cell;
a measured reference signal received power of the current serving cell;
a channel quality indicator for the current serving cell;
a signal to interference plus noise ratio for the current serving cell;
a detected Doppler frequency shift of the current serving cell; and
one or more timing advance commands received from a base station controlling the current serving cell.

5 . The method of claim 1 wherein determining whether the wireless device is moving toward the current serving cell of the wireless device or away from the current serving cell of the wireless device comprises determining a direction of movement of the wireless device relative to the current serving cell of the wireless device based on at least one of a group consisting of:
a location of the wireless device as determined via a positioning system; and
historical information.

6 . The method of claim 1 wherein:
initiating suppression of transmissions from the previous serving cell of the wireless device during detection of the predetermined signal from another cell comprises running a cell detection procedure with interference suppression of transmissions from the previous serving cell of the wireless device if the wireless device is moving toward the current serving cell; and
initiating suppression of transmissions from the current serving cell of the wireless device during detection of the predetermined signal from another cell comprises running the cell detection procedure with interference suppression of transmissions from the current serving cell of the wireless device if the wireless device is moving away from the current serving cell.

7 . The method of claim 1 further comprising:
determining whether the wireless device is in a high speed train scenario; and
upon determining that the wireless device is in a high speed train scenario, performing the steps of determining whether the wireless device is moving toward the current serving cell of the wireless device or away from the current serving cell of the wireless device, initiating suppression of transmissions from the previous serving cell of the wireless device during detection of the predetermined signal from another cell if the wireless device is moving toward the current serving cell, and initiating suppression of transmissions from the current serving cell of the wireless device during detection of the predetermined signal from another cell if the wireless device is moving away from the current serving cell.

8 . The method of claim 1 further comprising:
detecting a change of a state of the wireless device, the state of the wireless device being maintained as either moving toward the current serving cell of the wireless device or away from the current serving cell of the wireless device based on a direction of movement of the wireless device relative to the current serving cell of the wireless device; and
upon detecting a change of the state of the wireless device, performing the steps of determining whether the wireless device is moving toward the current serving cell of the wireless device or away from the current serving cell of the wireless device initiating suppression of transmissions from the previous serving cell of the wireless device during detection of the predetermined signal from another cell if the wireless device is moving toward the current serving cell, and initiating suppression of transmissions from the current serving cell of the wireless device during detection of the predetermined signal from another cell if the wireless device is moving away from the current serving cell.

9 . The method of claim 1 wherein:
determining whether the wireless device is moving toward the current serving cell of the wireless device or away from the current serving cell of the wireless device comprises determining that the wireless device is moving away from the current serving cell of the wireless device; and
initiating suppression of transmissions from the current serving cell of the wireless device during detection of the predetermined signal from another cell is performed upon determining that the wireless device is moving away from the current serving cell of the wireless device;
wherein the method further comprises, after performing an intra-frequency handover from the current serving cell to a new current serving cell, continuing to suppress transmission from the current serving cell of the wireless device during detection of the predetermined signal from another cell while the wireless device is moving toward the new current serving cell.

10 . The method of claim 1 further comprising:
if the wireless device is moving toward the current serving cell, compensating for a negative frequency offset during cell detection; and
if the wireless device is moving away from the current serving cell, compensating for a positive frequency offset during cell detection.

11 . The method of claim 10 wherein cell detection comprises detecting a secondary synchronization signal such that:
compensating for the negative frequency offset during cell detection comprises compensating for the negative frequency offset during detection of the secondary synchronization signal; and
compensating for the positive frequency offset during cell detection comprises compensating for the positive frequency offset during detection of the secondary synchronization signal.

12 . The method of claim 10 wherein the negative frequency offset is equal to −2 times a Doppler shift of a serving cell of the wireless device, and the positive frequency offset is equal to +2 times the Doppler shift of the serving cell of the wireless device.

13 .

Assignees

• Ericsson Telefon Ab L M

Inventors

• Axmon Joakim
• Alriksson Peter
• Palenius Torgny

Classifications

• H04W16/28

  using beam steering · CPC title

• H04B7/0842

  Weighted combining · CPC title

• H04B7/022 Primary

  Site diversity; Macro-diversity (using two or more spaced independent antennas H04B7/04) · CPC title

• H04B7/0404

  the mobile station comprising multiple antennas, e.g. to provide uplink diversity · CPC title

• H04W36/32 Primary

  by location or mobility data, e.g. speed data · CPC title