Employing smart antennas in the basestation of packet radio network is studied.An adaptive slot allocation multiple access protocol (ASAMA) is proposed.In ASAMA protocol

Time-Division Duplexing is adopted

and pilot signals are transmitted orderly by mobile terminals (MTs) at the beginning of one frame

so the spatial signatures of MTs can be obtained by the smart antennas.Based on the optimal SINR beamforming method

two slot allocation algorithms

which are point-by-point optimizing (PPO) and global optimizing (GO)

are presented.On condition that all packets can be received successfully

the basestation dynamically schedules uplink and downlink traffic to achieve that several data packets can be simultaneously transmitted in one traffic slot.Therefore

efficient space-division-multiple-access (SDMA) can be obtained.Approximate analysis of channel utilization is presented.Simulations show that ASAMA protocol effectively supports the application of smart antennas and provides higher channel utilization and lower delay.