Communications system, infrastructure equipment, communication terminal and method

Patent metadata

Field	Value
Publication number	US-10531383-B2
Application number	US-201414916897-A
Country	US
Kind code	B2
Filing date	Aug 4, 2014
Priority date	Sep 11, 2013
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

A communications system for communicating data to and from a communication terminal, including infrastructure equipment forming a mobile communications network arranged to transmit and receive signals representing data to and from the communication terminal via a wireless access interface. The communication terminal is configured to transmit and receive signals representing data to/from the infrastructure equipment and to enter a reduced-power state, during which the communication terminal is configured to periodically recover data from the signals received from the infrastructure equipment, to measure a parameter indicating a characteristic of at least some of the signals received from the infrastructure equipment during the reduced power state, and to exit the reduced power state and to transmit a message to the infrastructure equipment, the message requesting resources of the wireless access interface, in dependence upon the measured parameter relative to a predetermined threshold.

First claim

The invention claimed is:

1. A communications system comprising:
a first base station;
a second base station;
a communication terminal configured to communicate with the first base station and the second base station at least by transmitting and receiving signals to and from the first base station and the second base station;
wherein the communication terminal is configured to:
enter a reduced-power state;
obtain data from the signals received from the first base station and the second base station during the reduced-power state;
measure a parameter indicating a characteristic of at least some of the signals received from the first base station and the second base station during the reduced-power state;
determine a first radio link quality level of the first base station and a second radio link quality level of the second base station based on the measured parameter;
determine that the first radio link quality level of the first base station is below a first threshold, wherein the first threshold is dynamically adjustable based on (i) a probability of a radio link failure with the first base station, (ii) a first power consumed by the communication terminal when exiting from the reduced-power state relative to a second power consumed by the communication terminal as a result of the radio link failure, and (iii) a probability of the communication terminal exiting from the reduced-power state;
exit the reduced-power state when the first radio link quality level of the first base station is below the first threshold;
transmit a first message to the first base station upon exiting the reduced-power state, wherein the first message includes a report on the first radio link quality level;
determine that the second radio link quality level of the second base station is above a second threshold while the first radio link quality level of the first base station is below the first threshold; and
transmit a second message to the first base station upon determining that the second radio link quality level is above the second threshold while the first radio link quality level is below the first threshold, wherein the second message includes a report on the first and second radio link quality levels and a request for uplink resources to commence a handover of the communication terminal from the first base station to the second base station;

wherein the first base station is configured to receive the first message and the second message from the communication terminal and to grant the uplink resources to the communication terminal based on the request in the second message.

2. The communications system as claimed in claim 1 , wherein the reduced-power state includes a first period during which the communication terminal is configured to obtain the data from the signals and a second period during which the communication terminal is configured not to obtain the data from the signals, and
wherein the communication terminal is configured to measure the parameter during the second period.

3. The communications system as claimed in claim 1 , wherein the measured parameter includes a received power of a reference signal transmitted by the first base station.

4. The communications system as claimed in claim 1 , wherein the second threshold is greater than the first threshold.

5. The communications system as claimed in claim 1 , wherein the first threshold is determined by the first base station and the communications terminal is provided with an indication of the first threshold by the first base station.

6. The communications system as claimed in claim 1 , wherein the first threshold is stored in a memory of the communication terminal.

7. A communication terminal comprising:
a transceiver configured to communicate with a first base station and a second base station of a plurality of base stations at least by transmitting and receiving signals to and from the first base station and the second base station; and
a controller configured to:
enter a reduced-power state;
obtain data from the signals received from the first base station and the second base station during the reduced-power state;
measure a parameter indicating a characteristic of at least some of the signals received from the first base station and the second base station during the reduced-power state;
determine a first radio link quality level of the first base station and a second radio link quality level of the second base station based on the measured parameter;
determine that the first radio link quality level of the first base station is below a first threshold, wherein the first threshold is dynamically adjustable based on (i) a probability of a radio link failure with the first base station, (ii) a first power consumed by the communication terminal when exiting from the reduced-power state relative to a second power consumed by the communication terminal as a result of the radio link failure, and (iii) a probability of the communication terminal exiting from the reduced-power state;
exit the reduced-power state when the first radio link quality level of the first base station is below the first threshold;
transmit, via the transceiver, a first message to the first base station upon exiting the reduced-power state, wherein the first message includes a report on the first radio link quality level;
determine that the second radio link quality level of the second base station is above a second threshold while the first radio link quality level of the first base station is below the first threshold;
transmit, via the transceiver, a second message to the first base station upon determining that the second radio link quality level is above the second threshold while the first radio link quality level is below the first threshold, wherein the second message includes a report on the first and second radio link quality levels and a request for uplink resources to commence a handover of the communication terminal from the first base station to the second base station.

8. The communication terminal as claimed in claim 7 , wherein the reduced-power state includes a first period during which the communication terminal is configured to obtain the data from the signals and a second period during which the communication terminal is configured not to obtain the data from the signals, and
wherein the controller is configured to measure the parameter during the second period.

9. The communication terminal as claimed in claim 7 , wherein the measured parameter is a received power of a reference signal transmitted by the first base station.

10. The communication terminal as claimed in claim 7 , wherein the second threshold is greater than the first threshold.

11. The communication terminal as claimed in claim 7 , wherein the communication terminal is provided with an indication of the first threshold by the first base station.

12. The communication terminal as claimed in claim 7 , wherein the first threshold is stored in a memory of the communication terminal.

13. An infrastructure equipment comprising:
a transceiver configured to communicate with a communication terminal and a target base station at least by transmitting and receiving signals to and from the communication terminal and the target base station;
wherein the communication terminal is configured to:
enter a reduced-power state;
obtain data from signals received from the infrastructure equipment and the target base station during the reduced-power state;
measure a parameter indicating a characteristic of at least some of the signals received from the infrastructure equipment and the target base station during the reduced-power state;

Assignees

• Sony Corp

Inventors

• Kahtava Jussi
• Richards Derek John

Classifications

• H04W72/542

  using measured or perceived quality · CPC title

• H04W76/28

  Discontinuous transmission [DTX]; Discontinuous reception [DRX] · CPC title

• H04W52/0225 Primary

  using monitoring of external events, e.g. the presence of a signal · CPC title

• H04W36/26

  by agreed or negotiated communication parameters · CPC title

• H04W52/0245

  according to signal strength · CPC title