A radio receiver (300) includes: a decoding stage (301) configured to decode a downlink control channel (310) comprising an uplink grant and to derive a time budget (311) from a decoded uplink grant; a processing stage (302) configured to determine an amount of payload potentially generated for an uplink transport block (313) based on the time budget (311) and to generate a payload section (312) of the uplink transport block (313) based on the determined amount of payload; and an encoding stage (303) configured to generate a padding section of the uplink transport block (313) and to encode the uplink transport block (313) comprising the payload section (312) and the padding section.