| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The research results on the project "Simultaneous Spread-Time and Spread-Spectrum Modulations with Software Radio Techniques" are summarized as follows.
(1) The simultaneaous spread spectrum and spread time modulation system is developed. The modulation is obtained by the spread of spread spectrum FSK in time axis.
(2) The waveform, spectrum, and error probability of the developed system are given by the sumulations. The capacity of the system is derived theoretically, and it is shown to be the same as those of spread time PPM and spread spectrum FSK.
(3) In the simultaneous spread spectrum and spread time modulation system, the performance depends on the assignment method of channel resource, which is the number of independent dimensions employed in the bandwidth-time space. The assinment method is developed for an adaptive operation to the channel condition.
(4) The transmitter function of the simultaneous spread spectrum and spread time modulation system is included in the program of DSP, which generates the waveform of the system.
(5) As the error correction of the simultaneous spread spectrum and spread time modulation system, the separate coding with iterative decoding is introduced. The corelation information of the received PPM time slot is effectively employed at the iterative decoding, and the coding gain is shown to be almost the same as full states decoding. The turbo coding is also applied to the system for further improvement.
(6) For the efficient use of frequency spectrum, the new modulation is developed. The modulated signal is sent after the cut of discrete spectrum, and the spectrum is recovered in the receiver. The error probability for 1/2, 1/4, and 1/8 spectrum PPM is demonstrated for the example.
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