Patent ID: 7190689
Filing Date: 2007-03-13
Classification: H04L

Abstract:
1. A retransmission control apparatus for use in a radio communication system that uses an orthogonal frequency division multiplexing technique, said apparatus comprising: a transmitter which transmits to a radio station a data sequence, which serves as communication data that has been transformed into a time waveform of an orthogonal frequency division multiplexing symbol; a receiver which receives from said radio station a retransmission request for retransmitting the communication data; a transformation mechanism configured to transform, in response to the retransmission request, the data sequence of the communication data to be retransmitted into an orthogonal frequency division multiplexing symbol having a time waveform different from the time waveform of the orthogonal division multiplexing symbol which had been sent before the retransmission request; and a retransmitting mechanism configured to retransmit the communication data transformed by said transformation means to said radio station; wherein said transformation mechanism comprises: a scramble mechanism configured to scramble, in response to the retransmission request, the data sequence of the communication data to be retransmitted at least for the same communication data in accordance with a scramble sequence that varies every time the data sequence is retransmitted, and wherein the scramble sequence used by said scramble means varies according to the number of times that the retransmission request for the same communication data has been received.