| 摘要 |
<p>A base station supports a contention-based channel and a schedule-based channel. If too many mobile terminals simultaneously transmit on the contention-based channel, the base station schedules retransmissions to those terminals on the schedule-based channel. Supporting this, a terminal transmits a user transmission on the contention-based channel that includes both a data transmission and a reference signal. The terminal derives this reference signal by selecting one of a plurality of cyclic shifts (CSs). Correspondingly, the base station receives the user transmission and can determine the selected CS even if it is unable to demodulate the data transmission. The base station then determines a retransmission identifier (RTI) mapped to that CS, according to a mapping between CSs and RTIs, and sends scheduling information for any needed retransmission to the terminal by addressing that information to the RTI. Meanwhile, the terminal knows this mapping and monitors for scheduling information addressed to that RTI.</p> |
