In a packet repeater of a wireless base station, a packet analyzer receives uplink packets from mobile terminals and stores data indicating quality of each wireless link between the base station and each mobile terminal in a memory. A packet sorter receives downlink packets from a network and stores the received packets into buffers according to the destinations of downlink packets and their service classes. According to the data stored in the memory, packets in the buffers are into a first group of queues in which quality of service is not satisfied and a second group of queues in which quality of service is satisfied. A packet scheduler sequentially transmits all packets from the first-group queues to mobile terminals, and reorders the second-group queues in a descending order of their qualities of wireless links and sequentially transmits all packets from the reordered queues to the mobile terminals.