Radio communication system, method, base station and terminals

Application Number  00129213 Application Date  2000.09.28
Publication Number  1290080 Publication Date  2001.04.04
Priority Information   1999/9/28 JP 275225/1999  
Applicant(s) Name  K.K. Toshiba  
Inventor(s) Name  Kagami Kiyoshi  
Patent Agency Code  11038 Patent Agent  wu lili
AbstractThere is disclosed a multicast transmission system in which an efficient and highly reliable multicast transmission can be performed. In the multicast transmission system for performing multicast transmission to a plurality of terminal stations from a base station, when an error is detected in the terminal station, the terminal station utilizes some of sub-carriers constituting an OFDM symbol to generate and transmit a NAK signal to the base station. A level judgment section 25 in the base station resends a packet to each terminal station when a reception signal level exceeds a threshold. Since the number M of sub-carriers able to be utilized to generate the NAK signal and the number L of sub-carriers necessary for generating the NAK signal are determined based on the number of terminal stations, packet communication quality, and the like, an erroneous detection probability and detection miss probability of the NAK signal can both be lowered.