A radio communication system comprising: at least one interrogator including: means for transmitting a downlink information modulated radio signal for an interrogation; means for receiving an uplink radio signal; and, means for transmitting a downlink acknowledgement radio signal in response to receiving said uplink radio signal; and at least one tag including: means for receiving said downlink information modulated radio signal; and means for demodulating said downlink information modulated radio signal to recover said downlink information; characterized by the at least one tag further including: means for scheduling transmission of a plurality of said uplink radio signals for said interrogation, in response to receiving said downlink information modulated radio signal; means for transmitting said uplink radio signal using modulated backscatter in cooperation with said scheduling means; means for receiving said downlink acknowledgement radio signal; and means for canceling any remaining scheduled transmissions of said uplink radio signal upon receiving said downlink acknowledgement radio signal. at least one interrogator including: means for transmitting a downlink information modulated radio signal for an interrogation; means for receiving an uplink radio signal; and, means for transmitting a downlink acknowledgement radio signal in response to receiving said uplink radio signal; and means for transmitting a downlink information modulated radio signal for an interrogation; means for receiving an uplink radio signal; and, means for transmitting a downlink acknowledgement radio signal in response to receiving said uplink radio signal; and at least one tag including: means for receiving said downlink information modulated radio signal; and means for demodulating said downlink information modulated radio signal to recover said downlink information; characterized by the at least one tag further including: means for scheduling transmission of a plurality of said uplink radio signals for said interrogation, in response to receiving said downlink information modulated radio signal; means for transmitting said uplink radio signal using modulated backscatter in cooperation with said scheduling means; means for receiving said downlink acknowledgement radio signal; and means for canceling any remaining scheduled transmissions of said uplink radio signal upon receiving said downlink acknowledgement radio signal. means for receiving said downlink information modulated radio signal; and means for demodulating said downlink information modulated radio signal to recover said downlink information; characterized by the at least one tag further including: means for scheduling transmission of a plurality of said uplink radio signals for said interrogation, in response to receiving said downlink information modulated radio signal; means for transmitting said uplink radio signal using modulated backscatter in cooperation with said scheduling means; means for receiving said downlink acknowledgement radio signal; and means for canceling any remaining scheduled transmissions of said uplink radio signal upon receiving said downlink acknowledgement radio signal. means for scheduling transmission of a plurality of said uplink radio signals for said interrogation, in response to receiving said downlink information modulated radio signal; means for transmitting said uplink radio signal using modulated backscatter in cooperation with said scheduling means; means for receiving said downlink acknowledgement radio signal; and means for canceling any remaining scheduled transmissions of said uplink radio signal upon receiving said downlink acknowledgement radio signal.