User-Identification Position-Sensing Asynchronous CDMA Communication System Using Finite-Length PN-Sequences

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In the ad hoc network or sensor network, a technique to identify a signal sender and simultaneously to sense the position of the sender is desired. This project aimed to develop an asynchronous CDMA communication and position-sensing system using finite-length PN sequences. The achievements of the research are as the followings.(1) Research on real-valued finite-length sequences For this system, a sequence set to bring high transmission efficiency has been developed. For user's selective formation of wireless network, other sequence pairs with impulsive correlation are investigated, to bring a little lower transmission efficiency.(2) Development of multiplexing communication system The communication system for 4 users allotted by real-valued sequences of length 65 has been developed to transmit two-valued modulated signal from multi-rate data and to demodulate the data with interference, noise and amplitude distortion suppressed through correlation processing. This system has high efficiency of frequency usage and the stronger tolerance with amplitude distortion than the OFDM system (as adopted to terrestrial TV system).(3) The position sensing system has been developed to calculate the position by intersecting the hyperbolas derived from distance differences between a transmitting antenna and three Deceiving antennas placed on the apex of a triangle. The accuracy of detected position depends on the distances between the antennas and on the time interval of system clock.The developed system for detecting the person or object possessing a code and communicating with each is a proposal. The future subject is the research and development of improvements for practical use.