Communications device for determining beam failure during inactive state and method
A communications device is provided. The communications device comprises transceiver circuitry configured to transmit signals and receive signals to and from a wireless communications network, and controller circuitry. The controller circuitry is configured in combination with the transceiver circuitry to transmit to the wireless communications network, whilst operating in an inactive state, one or more signals comprising uplink data using a first of a plurality of beams each for transmission in a different one of a plurality of spatial directions, to detect, whilst operating in the inactive state, that the first beam satisfies a beam failure condition a specified number of consecutive times, and subsequently to determine, whilst operating in the inactive state, that the first beam has failed.
1. A communications device comprising
transceiver circuitry configured to transmit signals and receive signals to and from a wireless communications network, and
controller circuitry configured in combination with the transceiver circuitry
to transmit to the wireless communications network, whilst operating in an inactive state, one or more signals comprising uplink data using a first of a plurality of beams each for transmission in a different one of a plurality of spatial directions,
to detect, whilst operating in the inactive state, that the first beam satisfies a beam failure condition a specified number of consecutive times, subsequently
to determine, whilst operating in the inactive state, that the first beam has failed,
to reset, whilst operating in the inactive state, a timer each time a signal comprising uplink data is transmitted, the timer being configured to expire after a specified period of time, and
to detect, whilst operating in the inactive state, that the beam failure condition is satisfied when the communications device determines that a response has not been received from the wireless communications network for a transmitted signal comprising uplink data before the timer has expired.
2. The communications device according to claim 1 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to perform, whilst operating in the inactive state, measurements on the first beam, and
to detect, whilst operating in the inactive state, that the beam failure condition is satisfied when a value of the measurement of the first beam is below a threshold value.
3. The communications device according to claim 2 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to perform, whilst operating in the inactive state, measurements on one or more others of the plurality of beams to the first beam,
to select, whilst operating in the inactive state, one of the other beams on which the measurements were performed, the selected other beam having been measured by the communications device to have a value of the measurement above the threshold value, and
to initiate, whilst operating in the inactive state, a random access, RACH, procedure with the wireless communications network using the selected other beam, the initiated RACH procedure providing an indication to the wireless communications network that the first beam has failed and an indication that the communications device is performing a beam failure recovery procedure.
4. The communications device according to claim 3 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to receive, from the wireless communications network whilst operating in the inactive state, a response message to the imitated RACH procedure, and
to determine, based on the reception of the response message and whilst operating in the inactive state, that the beam failure recovery procedure is successful.
5. The communications device according to claim 3 , wherein the first beam and the selected other beam form part of a same cell of the wireless communications network.
6. The communications device according to claim 2 , where the measurements are performed with a set period.
7. The communications device according to claim 2 , where the measurements comprise one or both of a Channel State Information-Reference Signal-Reference Signal Received Power, CSI-RS-RSRP, measurement and a Synchronisation Signal Block-Reference Signal Received Power, SSB-RSRP, measurement.
8. The communications device according to claim 2 , where the threshold value is predetermined and known to the communications device.
9. The communications device according to claim 2 , where an indication the threshold value is received by the communications device as a signal from the wireless communications network.
10. The communications device according to claim 1 , where the specified period of time is predetermined and known to the communications device.
11. The communications device according to claim 1 , where an indication of the specified period of time is received by the communications device as a signal from the wireless communications network.
12. The communications device according to claim 1 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to initiate, whilst operating in the inactive state, RACH procedure with the wireless communications network, and
to express an intention for transition from the inactive state into a connected state with the wireless communications network.
13. The communications device according to claim 12 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to transmit, whilst operating in the connected state, the signals comprising uplink data to the wireless communications network.
14. The communications device according to claim 1 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to transition from the inactive state into an idle state.
15. The communications device according to claim 14 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to receive, whilst operating in the idle state, a paging message from a core network, CN, part of the wireless communications network, the paging message indicating that the communications device should transition from the idle state into a connected state with the wireless communications network, and
to transition from the idle state into the connected state with the wireless communications network.
16. The communications device according to claim 15 , wherein the controller circuitry is configured in combination with the transceiver circuitry
to transmit, whilst operating in the connected state, the signals comprising uplink data to the wireless communications network.
17. A method of operating a communications device, the method comprising
transmitting to the wireless communications network, whilst operating in an inactive state, one or more signals comprising uplink data using a first of a plurality of beams each for transmission in a different one of a plurality of spatial directions,
detecting, whilst operating in the inactive state, that the first beam satisfies a beam failure condition a specified number of consecutive times, subsequently
determining, whilst operating in the inactive state, that the first beam has failed,
resetting, whilst operating in the inactive state, a timer each time a signal comprising uplink data is transmitted, the timer being configured to expire after a specified period of time, and
detecting, whilst operating in the inactive state, that the beam failure condition is satisfied when the communications device determines that response has not been received from the wireless communications network for a transmitted signal comprising uplink data before the timer has expired.
18. A method of operating an infrastructure equipment forming part of a wireless communications network, the method comprising
transmitting, to a communications device whilst the communications device is operating in an inactive state, one or more downlink signals using a first of a plurality of beams each for transmission in a different one of a plurality of spatial directions,
detecting that, for a specified number of consecutive times, a response to one or more of the downlink signals has not been received from the communications device, subsequently
determining that the first beam has failed, and
resetting, whilst operating in the inactive state, a timer each time a signal comprising uplink data is transmitted, the timer being configured to expire after a specified period of time,
detecting, whilst operating in the inactive state, that the beam failure condition is satisfied when the communications device determines that response has not been received from the wireless communications network for a transmitted signal comprising uplink data before the timer has expired.