Wireless communication system

A modulator applied to a wireless communication system that conducts wireless communication by a multi-carrier modulation level using a communication frame composed of a plurality of slots;

• comprising:
• a slot generation part generating said slots by multiplexing header information containing at least channel estimation information for estimating channel, modulation level information for notifying a receiving side of a modulation level of each sub-carrier, and user data;
• and
• a slot number information generation part that estimates the number of slots in which said modulation level information is to be contained and generates slot number information for notifying the receiving side of said estimated number of slots, wherein
• said slot generation part generates, after generating said estimated number of slots by adding said slot number information to said modulation level information, slots which do not contain said modulation level information in a relevant communication frame.

A demodulator applied to a wireless communication system that conducts wireless communication by a multi-carrier modulation level using a communication frame composed of a plurality of slots containing at least modulation level information to notify a receiving side of a modulation level of each sub-carrier and user data;

• said modulator comprising:
• an extraction part extracting said modulation level information and slot number information added to said modulation level information to indicate the number of slots containing said modulation level information existing in same said communication frame;
• a modulation level/slot number information demodulation part demodulating said extracted modulation level information and slot number information;
• and
• a user data demodulation part that determines whether or not said modulation level information and slot number information has been successfully demodulated and, when said demodulation has been successful, eztracts said number of slots to identify a last slot containing said modulation level information and slot number information based on the extracted number of slots, and uses said successfully demodulation level information to demodulate each sub-carrier corresponding to said user data of each slot existing in the same communication frame after the slot following said identified slot.