Pulse or digital communications – Repeaters – Testing
Patent
1994-02-23
1996-10-01
Cain, David C.
Pulse or digital communications
Repeaters
Testing
H04K 100
Patent
active
055616860
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a radio information communication system for constructing an information transmission network represented by a LAN (Local Area Network) by use of a radio circuit.
BACKGROUND ART
In the premises of a university, office or factory, a wired LAN using coaxial cables is often used in order to effect data transfer between information communication devices such as personal computers, work stations or facsimile devices. However, in the wired LAN, a large-scale work must be effected when the layout is changed after construction of the system. Thus, it has a problem that it is difficult to easily cope with a change in the layout after construction of the system. Therefore, recently, it is strongly required to provide a LAN using a radio circuit.
However, many factors must be taken into consideration in order to realize the radio LAN. For example, they include band-narrowing of the frequency band to be used, suppression of influences by the multipath and portabi-frequency selectivity fading, and achievement of portability of terminal devices as typical factors.
Conventionally, various studies have been made for the above various problems. However, effective solutions are not yet provided.
DISCLOSURE OF INVENTION
A first object of this invention is to provide a radio information communication system for permitting the radio information communication of high quality to be effected by suppressing influences by the frequency selectivity fading and multipath.
A second object of this invention is to provide a radio information communication system for permitting the high quality communication to be effected by suppressing influences by interfering waves even when an interfering wave generating source is present in or near the radio area.
A third object of this invention is to provide a radio information communication system which makes it possible to suppress influences by the frequency selectivity fading and multipath without using a complicated signal process and large-scale antenna, thereby permitting a radio station to be easily constructed at low cost and providing sufficient portability due to the small size and light weight for the radio station.
A fourth object of this invention is to provide a radio information communication system capable of suppressing a frequency band to be used to a narrow bandwidth.
A fifth object of this invention is to provide a radio information communication system capable of reducing the data discarding ratio by permitting data re-transmission, thereby making it possible to keep the throughput high.
A sixth object of this invention is to provide a radio information communication system and an error correction method capable of efficiently correcting errors occurring in a reception bit string.
A seventh object of this invention is to provide a radio information communication system for permitting the same frequency to be used in a plurality of adjacent radio zones by steadily avoiding collision between transmission information items, thereby making it possible to enhance the utilization factor of the frequency.
This invention is constructed as follows in order to attain the above first to fourth objects. That is, when transmission data is transmitted by radio in a radio information communication terminal device on the transmission side, at least part of a transmission data string is first divided into a plurality of bit strings. A plurality of carrier waves having different frequencies are subjected to the primary modulation by use of the divided bit strings. Then, each of the primary-modulated carrier waves is subjected to the secondary modulation by the spread spectrum system and a modulated wave obtained by the secondary modulation is transmitted.
Therefore, according to this invention, the data string is divided into a plurality of bit strings which are then transmitted in parallel. For this reason, the transmission speed of each bit string can be made low. Therefore, it becomes possible to set time for one symbol of the carrier wave mo
REFERENCES:
patent: 3916313 (1975-10-01), Lowry
patent: 4355399 (1982-10-01), Timor
patent: 4515852 (1985-05-01), Katabe et al.
patent: 4584678 (1986-04-01), Ozeki et al.
patent: 5029183 (1991-07-01), Tymes
Communication from European Patent Office dated Feb. 3, 1995.
Laurence B. Milstein et al., "Coding and Modulation Techniques for Freuency-Hopped Spread-Spectrum Communications Over a Pulse-Burst Jammed Rayleigh Fading Channel," IEEE Journel on Selected Areas in Communications, SAC-3, No. 5, Sep. 1985 (New York).
"Pulsed FM(Chirp) Systems", R. C. Dixon, Spread Spectrum Systems, pp. 40-43, 1976.
Haruyama Hideaki
Kamura Kouichiro
Kobayashi Hiroshi
Ozawa Kazuyoshi
Yano Motomitsu
Cain David C.
Kabushiki Kaisha Toshiba
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