Occupied target channel notification for conditional handovers with unlicensed frequency bands
A user equipment (UE) device receives, from base station providing a source cell, a conditional handover command identifying a target frequency on a target cell for conditional handover. After determining that conditions have been met for the conditional handover, the UE device observes the target frequency. If the target frequency is occupied, the UE device transmits, to the serving base station, an indication that the target frequency is unavailable for the conditional handover. The indication may include, or be transmitted with, a measurement report.
1. A method performed at a communication device, the method comprising:
receiving, from a serving base station providing a source cell, a conditional handover command identifying a target frequency on a target cell for conditional handover;
determining conditions have been met for the conditional handover;
determining the target frequency is not available for the conditional handover; and
transmitting, to the serving base station, an indication that the target frequency is unavailable for the conditional handover.
2. The method of claim 1 , wherein the conditional handover command comprises a plurality of target frequencies and the indication identifies each target frequency determined to be unavailable for the conditional handover.
3. The method of claim 2 , further comprising: receiving an updated conditional handover command that does not include each target frequency determined to be unavailable for the conditional handover.
4. The method of claim 1 , wherein the transmitting the indication comprises transmitting a measurement report indicating at least a Received Signal Strength Indicator (RSSI) measurement and a channel occupancy indicator for each target cell frequency determined to be unavailable for the conditional handover.
5. The method of claim 1 , where in the conditional handover command further indicates a source cell frequency for the conditional handover, the method further comprising:
in response to determining the target cell target frequency is unavailable for the conditional handover, performing the conditional handover to the source cell frequency.
6. The method of claim 1 , further comprising: receiving an updated conditional handover command that does not include the target frequency.
7. The method of claim 1 , further comprising performing a minimum drive test (MDT) logging procedure comprising:
logging MDT logged information identifying at least one target cell frequency unavailable for the conditional handover and comprising at least one of a channel occupancy of the at least one target cell frequency, an Received Signal Strength Indicator (RSSI) of the at least one target cell frequency, a location, a time stamp, a cell ID, a wireless local area network service set identifier (WLAN SSID), and a base service set identifier (BSSID); and
reporting the MDT logged information to a network of the base station after connection to the network.
8. A user equipment communication device (UE device) comprising:
a receiver configured to receive, from a serving base station providing a source cell, a conditional handover command identifying a target frequency on a target cell for conditional handover;
a controller configured to determine that conditions have been met for the conditional handover and to determine that the target frequency is not available for the conditional handover; and
a transmitter configured to transmit, to the serving base station, an indication that the target frequency is unavailable for the conditional handover.
9. The UE device of claim 8 , wherein the conditional handover command comprises a plurality of target frequencies and the indication identifies each target frequency determined to be unavailable for the conditional handover.
10. The UE device of claim 9 , the receiver further configured to receive an updated conditional handover command that does not include each target frequency determined to be unavailable for the conditional handover.
11. The UE device of claim 8 , wherein the transmitted is configured to transmit a measurement report indicating at least a Received Signal Strength Indicator (RSSI) measurement and a channel occupancy indicator for each target cell frequency determined to be unavailable for the conditional handover.
12. The UE device of claim 8 , where in the conditional handover command further indicates a source cell frequency for the conditional handover, the controller further configured to, in response to determining the target cell target frequency is unavailable for the conditional handover, perform the conditional handover to the source cell frequency.
13. The UE device of claim 8 , the receiver further configured to receive an updated conditional handover command that does not include the target frequency.
14. The UE device of claim 8 , the controller configured to perform a minimum drive test (MDT) logging procedure comprising:
logging MDT logged information identifying at least one target cell frequency unavailable for the conditional handover and comprising at least one of a channel occupancy of the at least one target cell frequency, an Received Signal Strength Indicator (RSSI) of the at least one target cell frequency, a location, a time stamp, a cell ID, a wireless local area network service set identifier (WLAN SSID), and a base service set identifier (BSSID), the transmitter configured to transmit the MDT logged information to a network of the base station after connection to the network.