Cell reselection using not updated mobility information

Patent metadata

Field	Value
Publication number	US-10506478-B2
Application number	US-201615553462-A
Country	US
Kind code	B2
Filing date	Mar 22, 2016
Priority date	Apr 20, 2015
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

A communications device for communicating via a mobile communications network, includes a transmitter, a receiver, and a controller. The transmitter is configured to transmit signals to one or more infrastructure equipment of the mobile communications network when in a connected mode, the receiver is configured to receive signals from the infrastructure equipment, and the controller is configured to control the receiver to acquire mobility information, the mobility information providing an indication of communications parameters relating to a wireless access interface provided by one or more infrastructure equipment for receiving signals at the receiver. When in an idle mode, the controller is configured to measure signals received from at least one of the one or more infrastructure equipment using latest mobility information, and to perform a cell reselection process based on the measured signals to reselect one of the one or more infrastructure equipment, using the latest mobility information.

First claim

The invention claimed is:

1. A communications device for communicating via a mobile communications network, the communications device comprising:
a transmitter configured to transmit signals to one or more infrastructure equipment of the mobile communications network via a wireless access interface provided by the one or more infrastructure equipment when in a connected mode;
a receiver configured to receive signals from the one or more infrastructure equipment via the wireless access interface; and
a controller configured to control the receiver to acquire mobility information, the mobility information providing an indication of communications parameters relating to the wireless access interface provided by the one or more infrastructure equipment for receiving signals at the receiver, and the controller is further configured
to store the mobility information as the latest mobility information in a data store,
to detect that the communications device cannot receive updated mobility information broadcast by a first of the one or more infrastructure equipment or any of the other one or more infrastructure equipment when a location of the communications device is changed from being completely out of coverage into a coverage enhanced region of the first of the one or more infrastructure equipment, and
when in an idle mode and the controller detects that the communication device cannot receive the updated mobility information based on the changed location
to measure signals received from at least one of the one or more infrastructure equipment using the latest mobility information stored in the data store, and
to perform a cell reselection process based on the measured signals in order to reselect one of the one or more infrastructure equipment, using the latest mobility information stored in the data store, only when the communication device previously received mobility information from a third of the one or more infrastructure equipment that is a neighbor of the first of the one or more infrastructure equipment.

2. The communications device as claimed in claim 1 , wherein the controller is configured with the receiver
to detect that the communications device cannot receive updated mobility information by determining that the communications device has entered a coverage extension condition in which data is communicated with the communications device by repeated transmission of signals representing the data to extend a radio coverage provided by one or more of the one or more infrastructure equipment.

3. The communications device as claimed in claim 1 , wherein the controller is configured in combination with the receiver
to detect that system information received from a infrastructure equipment relating the wireless access interface has become invalid,
to determine that the communications device is in a coverage extension mode for signals received from the first infrastructure equipment, for which updated mobility information cannot be received as part of the system information, and
to reuse the latest mobility information received from the first infrastructure equipment when in the coverage extension mode.

4. The communications device as claimed in claim 1 , wherein the controller is configured in combination with the receiver
to detect that system information received from a first of the one or more infrastructure equipment relating the wireless access interface has become invalid,
to determine that the communications device is in a coverage extension mode for signals received from a second infrastructure equipment of the one or more infrastructure equipment, for which updated mobility information cannot be received as part of the system information, and
to reuse the latest mobility information received from the first infrastructure equipment when in the coverage extension mode.

5. The communications device as claimed in claim 4 , wherein the controller is configured
to detect that the communications device can receive signals from the second infrastructure equipment in a coverage extension mode in which updated mobility information cannot be received by the communications device from the second infrastructure equipment,
to form a list of the one or more infrastructure equipment as candidates for reselection using the latest mobility information stored in the data store, the list being formed to include an indication the second infrastructure equipment as a current cell and the first infrastructure equipment as a neighbouring cell.

6. The communications device as claimed in claim 1 , wherein the controller is configured to control the receiver to receive system information provided in system information block transmitted repeatedly to extend a radio coverage of a cell served by the one or more infrastructure equipment, wherein the mobility information is not transmitted repeatedly with the system information so that the receiver cannot receive the updated mobility information when in a coverage extension mode.

7. The communications device as claimed in claim 1 , wherein the controller is configured with the transmitter and the receiver
to request from the first infrastructure equipment the updated mobility information,
to receive in response to the request the updated mobility information, and
to store the received updated mobility information in the data store as the latest mobility information.

8. The communications device as claimed in claim 1 , wherein the controller is configured with the receiver
to scan for signals transmitted by the one or more infrastructure equipment, to detect a plurality of the one or more infrastructure equipment as candidates for reselection,
to form updated mobility information from the detected candidate infrastructure equipment,
to store the updated mobility information as the latest mobility information in the data store, and
to use the updated mobility information for measuring the signals received from the candidate infrastructure equipment using the latest mobility information stored in the data store, and performing the cell reselection process based on the measured signals.

9. The communications device as claimed in claim 8 , wherein the controller is configured
to detect that the receiver cannot receive signals from one of more of the one or more infrastructure equipment identified by the latest mobility information stored in the data store, and if the receiver cannot receive the signals from the identified infrastructure equipment,
to scan for the signals transmitted by the one or more infrastructure equipment, to detect the plurality of the one or more infrastructure equipment as candidates for reselection.

10. The communications device as claimed in claim 1 , wherein the controller is configured with the receiver to acquire the latest mobility information by
scanning for signals transmitted by the one or more infrastructure equipment,
detecting one or more of the one or more infrastructure equipment as candidates for reselection using predetermined signal detection thresholds, and
forming the latest mobility information from the one or more detected candidate infrastructure equipment.

11. The communications device as claimed in claim 1 , wherein the controller is configured with the receiver to acquire the latest mobility information by
receiving the latest mobility information which has been broadcast by a first of the one or more infrastructure equipment.

12. A method of controlling a communications device for communicating via a mobile communications network, the method comprising:
transmitting signals from the communications device to one or more infrastructure equipment of the mobile commun

Assignees

• Sony Corp

Inventors

• Martin Brian Alexander

Classifications

• H04W36/0061 Primary

  of neighbour cell information · CPC title

• H04W36/0083

  Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists · CPC title

• H04W36/00837

  Determination of triggering parameters for hand-off · CPC title

• H04W36/00835

  Determination of neighbour cell lists · CPC title