| 摘要 |
In a communication system, when packet data units (PDUs) to be transmitted from a transmitter apparatus are modulated according to Orthogonal Frequency Division Multiplexing (OFDM), the waveforms representing the modulated PDUs will experience different peak to average ratio values (PAR) making the PDUs differently sensitive to non-ideal transmitter characteristics. To minimize errors in the transmitted PDUs, at least two PDUs ( 304, 305, 306 ) are scrambled and modulated in parallel and substantially simultaneously in the transmitter ( 100 ), and the PAR values of the at least two PDUs ( 304, 305, 306 ) are determined at each transmit instance. The measured PAR values of the at least two PDUs are compared in a scheduler ( 310 ), and the scheduler selects for transmission the PDU with the lowest PAR value. The scheduler ( 310 ) then instructs the transmitter ( 100 ) to transmit the selected PDU. If the PDUs that were not selected for transmission are re-scrambled and re-modulated before they are transmitted, the average PAR value for a transmitted PDU can be lowered by 2-3 dB with the invention if 8 PDUs are compared at each transmit instance.
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