In a packet data transmission and reception system, a media access control (MAC) message is broadcast by a base station to a plurality of mobile stations. The MAC message contains packet data transmission scheduling information which allows the base station to preemptively control mobile station access to traffic channels in order to maximize the efficiency of packet data transmissions and allow scheduling consideration including priority access, quality of service and maximum bytes per transfer. The MAC message consists of a control frame structure, which comprises scheduling parameters including MAC IDs fields, activity fields, and a field representing the number of free traffic channels in a cell. These parameters enable multiple mobile stations to share, in a time multiplexed fashion, traffic channels for packet data transmission on CDMA based mobile communication systems.