Two-stage grants in unlicensed cells

A radio base station for scheduling a user equipment with uplink radio resources on an unlicensed cell, wherein at least one unlicensed cell is configured for communication between the user equipment and the radio base station, the radio base station comprising;

• a processor, which in operation, generates a first-stage uplink resource scheduling message and a second-stage uplink resource scheduling message that is related to the first-stage uplink resource scheduling message,
• the first-stage uplink resource scheduling message indicating uplink radio resources usable by the user equipment to perform an uplink transmission via the unlicensed cell and a time period,
• the generating of the first-stage uplink resource scheduling message including setting one or more bits of one or more data fields in the first-stage uplink resource scheduling message to respectively predetermined values,
• the user equipment determines that the first-stage uplink resource scheduling message is valid in case the one or more bits of the one or more data fields are confirmed to be set to the respective predetermined values and the second-stage uplink resource scheduling message is received within the time period after reception of the first-stage uplink resource scheduling message,
• the user equipment determines that the uplink transmission is scheduled in case the user equipment determines that the first-stage uplink resource scheduling message is valid,
• the user equipment, in case the user equipment determines that the uplink transmission is scheduled, performs the uplink transmission via the unlicensed cell according to the uplink radio resources indicated in the first-stage uplink resource scheduling message;
• and
• a transmitter, which in operation, transmits the first-stage uplink resource scheduling message to the user equipment, and transmits the second-stage uplink resource scheduling message to the user equipment subsequent to the first-stage uplink resource scheduling message being transmitted to the user equipment.

A method performed by a user equipment for being scheduled with uplink radio resources, wherein at least one unlicensed cell is configured for communication between the user equipment and a radio base station that is responsible for scheduling uplink radio resources on the unlicensed cell, the method comprising:

• receiving, from the radio base station, a first-stage uplink resource scheduling message indicating uplink radio resources usable by the user equipment to perform an uplink transmission via the unlicensed cell and a time period;
• receiving, from the radio base station and subsequent to the first-stage uplink resource scheduling message being received, a second-stage uplink resource scheduling message that is related to the first-stage uplink resource scheduling message;
• determining whether the first-stage uplink resource scheduling message is valid or not, the first-stage uplink resource scheduling message being determined to be valid in case one or more bits of one or more data fields in the first-stage uplink resource scheduling message are set to respectively predetermined values and the second-stage uplink resource scheduling message is received within the time period after reception of the first-stage uplink resource scheduling message;
• determining that the uplink transmission is scheduled in case the first-stage uplink resource scheduling message is determined to be valid;
• and
• performing, in case it is determined that the uplink transmission is scheduled, the uplink transmission via the unlicensed cell according to the uplink radio resources indicated in the first-stage uplink resource scheduling message.