This disclosure relates to techniques for reducing latency in a high-propagation-delay wireless communication system. A base station (BS) may receive from a user equipment (UE) a first buffer status report (BSR) indicating an amount of uplink data buffered by the UE for transmission to the BS, and may subsequently receive a first BSR update message indicating that an additional amount of uplink data has been buffered by the UE subsequent to transmission of the first BSR. The first BSR update message may be received prior to expiration of a timer authorizing transmission of a second BSR following the first BSR. In response, the BS may allocate resources for transmission to the UE, based on the first BSR and the first BSR update message. The BS may provide an uplink grant identifying the allocated resources.