| 摘要 |
PURPOSE:To relax the congestion of the system by employing multiplex level modulation or QAM so as to revise a modulation scheme for a period when the processing quantity is a maximum thereby sending plural spread aloha packets in parallel. CONSTITUTION:A data packet outputted from a BBP 10 is stored in a buffer memory 11, spread timewise by a logic circuit 12 and extracted sequentially, then converted into an analog signal by a D/A converter 13. A modulator 14 modulates a carrier by using a converted analog signal and outputs an intermediate frequency signal. When the communication processing quantity is increased, a binary phase-shift keying (BPSK) scheme is expanded into a multiplex level BPSK (M-BPSK) or quadrature amplitude modulation (QAM) scheme. Moreover, a modulation bit map is changed from the BPSK into the M-BPSK or QAM map dynamically. Then the spread aloha packet depending on the selected modulation scheme is sent in parallel by using the buffer memory 11. |
