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Shuichi TOMABECHI Atsushi KOMURO Takashi KONNO Hiroyuki NAKASE Kazuo TSUBOUCHI
We have proposed and implemented a spread spectrum (SS) wireless switch using 2.4 GHz front-end AlN/Al2O3 surface acoustic wave (SAW) matched filter (MF). Since the SAW MF has radio frequency (RF) front-end operation, RF components are not needed in the received circuit. High impedance in the peripheral circuit using passive devices has been employed for low current consumption. The SS wireless switches have been designed with the power consumption of less than 100 µW by using the SAW MF. It is confirmed that implemented SS wireless switch has a long battery life of 10 years and communication range of 30 m.
Hiroyuki NAKASE Yosuke IIZUKA Suguru KAMEDA Shuichi TOMABECHI Atsushi KOMURO Kazuo TSUBOUCHI
We have proposed the packet SS-CDMA scheme for downlink of SS-CDMA flexible wireless cellular network. Transmission packet is framed with synchronization block with 11 chip Barker code and information block with orthogonal spreading code. The chip synchronization is carried out using short code surface acoustic wave (SAW) matched filter. The code de-spreading is carried out using in-line de-spreader. Multi-channel downlink of 63 channels can be designed using orthogonal m-sequence. Simulation results show more than 15 channels without degradation from theoretical value can be used under multi-path environment. The packet SS-CDMA modem has been implemented using a 2.4 GHz front-end SAW matched filter. Degradation of Eb/N0 of less than 0.5 dB is experimentally achieved with four-channel multiplex.
Hiroyasu ISHIKAWA Hideyuki SHINONAGA Hideo KOBAYASHI
A wireless communications system with a transmission rate of 10 Mbit/s using Japanese ISM band (2471-2497 MHz) is presented. This system employs a novel spread spectrum multiple access method named "CFO-SS (Carrier Frequency Offset-Spread Spectrum)" method. In the CFO-SS system, a single PN code is commonly assigned to all the multiple carriers, and the frequency offset between the carriers is determined by the information symbol rate, which is small as compared with the spread bandwidth of the signal. Bit error rate performance of the proposed CFO-SS system under multipath environments is investigated by computer simulation, and the performance of the CFO-SS method is confirmed for wireless LAN systems using the 2.4 GHz ISM band.