National Institute of Information and Communications Technology, Incorporated

Sumitomo Osaka Cement Co., Ltd.

National Institute of Information and Communications Technology, Incorporated Administrative Agency

Sharp Kabushiki Kaisha Corporation

Oki Electric Industry Co., Ltd.

Communications Research Laboratory, Independent Administrative Institution

Yozo Shoji

Hiroyo Ogawa

Kiyoshi Hamaguchi

Yoshihiro Hashimoto

Junichiro Ichikawa

Hiroyuki Tsuji

Eiji Suematsu

Kaoru Higuma

Shingo Mori

Seiji Nishi

Hok Huor Ou

Hirokazu Sawada

A channel characteristic analyzing apparatus that can ensure modeling of a more adequate propagation path by processing position parameters needed in a two-wave model which is used as a line-of-sight propagation path model in a stochastic manner is provided. The channel characteristic analyzing apparatus for analyzing the propagation channel characteristics of a reception apparatuswhich has received a radio signal of a millimeter wave band, transmitted from a transmission antennaof a transmission apparatus, via a reception antenna, includes computation means which computes h(t) expressed by the following equation (1) as a channel response to the propagation channel characteristic.()=&#x3b2;&#x3b4;()&#x2003;&#x2003;(1)where &#x3b2; is derived as a result of processing the position parameters needed also in the two-wave model in the stochastic manner.

Channel characteristic analyzing apparatus and method

Disclosed is a wireless communication method for executing transmission and reception of a radio signal among communication terminals via a plurality of base stations connected to an IP (Internet Protocol) network. One of the base stations performs AD conversion on a radio signal received via an antenna from one of the communication terminals without demodulation, packetizes the AD-converted radio signal into packet data, and transmits the packet data to another base station over the IP network. The another base station performs DA conversion on the packet data received over the IP network from the one base station, transforms the DA-converted packet data into a radio signal without modulation, and transmits the radio signal to another base station via the antenna.

Wireless communication system

A low-cost, compact circular waveguide array antenna which improves an antenna reflection loss characteristic and enables an improvement in radiation characteristics, particularly radiation gain. The circular waveguide array antenna includes feeding portions which feed electromagnetic waves to one ends of circular waveguides and radiation apertures which radiate the electromagnetic waves at the opposite ends. Each circular waveguide includes a conical horn, with a diameter of a feeding side aperture at the feeding portion end being a, a diameter of the radiation aperture being d, which is larger than the diameter a of the feeding side aperture, and an opening angle being 2&#x3b1;. If a wavelength of a central frequency of an employed frequency band is &#x3bb;, then a value of &#x3b1;, which is half of the opening angle, is set between 0.8&#xd7;Arcsin(0.1349114/(d/&#x3bb;)) and 1.2&#xd7;Arcsin(0.1349114/(d/&#x3bb;)).

Circular waveguide antenna and circular waveguide array antenna

A method for generating a carrier residual signal and its device, in which a heterodyne optical signal used in a photometric field or an optical fiber radio communication field can be stably generated with a simplified structure. The device includes an optical modulating unit that includes a light source generating a light wave having a specific wavelength, and an SSB optical modulator. A light wave emitted from the light source enters into the optical modulating unit. A light wave emitted from the optical modulating unit includes a carrier component related to a zero-order Bessel function and a specific signal component related to a specific high-order Bessel function while suppressing signal components other than the specific signal component related to the specific high-order Bessel function, and a ratio of optical intensity between the carrier component and the specific signal component is set substantially to 1.

Method for generating carrier residual signal and its device

A transmitter shown in FIG.inputs to a mixeran IF band modulation signal generated from transmission data and a frequency hopping signal obtained by a hopping synthesizercontrolled by a hopping pattern generator, thereby obtaining a frequency hopping radio signal to be transmitted. In a receiver shown in FIG., a received signal is amplified and an unnecessary wave is removed from the signal, and the resultant signal is input to a mixer. The mixerreceives an output signal of a hopping synthesizercontrolled by a signal obtained by adding a fixed frequency offset signal to the hopping pattern generator. A signal downconverted to a first IF band without frequency hopping corresponding to the offset signal with a radio frequency band signal maintaining the relative spectrum relationship appears in the output of the mixer. An unnecessary wave of the signal is removed, a square unitperforms square detection, and a modulation signal in the intermediate frequency band used by the source is regenerated. The obtained IF band signal is modulated, thereby receiving desired data.

Method and system for frequency hopping radio communication

In a radio optical fusion communication system with the integration of an optical fiber transmission path and a radio propagation path, wherein by first and second light sources, an intermediate-frequency signal generating means for generating a modulating signal at an intermediate frequency band, a modulator for modulating an optical signal from the first light source into an SSB modulated optical signal using the intermediate-frequency signal, and an optical mixer for mixing the modulated optical signal with the optical signal from the second light source to obtain an optical transmission signal in a base station, the frequency of either of the optical signals is controlled such that the difference in frequency between the optical signals is a desired frequency of a modulated radio signal, thus switching the frequency channel of the modulated radio signal in the radio propagation path.

Method for changing frequency and base station in radio optical fusion communication system

The present invention provides a radio communication device, a transmitter and a receiver capable of handling a plurality of signal waves. A radio communication device has a millimeter-wave transmitter () and a millimeter-wave receiver (). Millimeter-wave transmitter () includes a multiplexing circuit (), a millimeter-wave up-converter () and an antenna (), and the millimeter-receiver includes an antenna (), a millimeter-wave down-converter () and an output processing circuit (). The signal waves dedicated to the user are modulated by a modulation circuit (to) so as to be allocated between the ground broadcast waves and satellite broadcast waves. The frequencies are multiplexed in an intermediate frequency band, after that, the multiplexed frequencies are converted into a millimeter-wave band and the resultant is transmitted. On the reception side, the multiplexed waves are down-converted, separated to signal waves and demodulated.

Radio communication apparatus, transmitter apparatus and receiver apparatus

A receiver receives an RF-band modulated signal transmitted from a transmitter, as well as an un-modulated carrier also transmitted from the transmitter and having a phase noise characteristic coherent with that of the modulated signal, and a product of the two components is generated to thereby restore an IF-band transmission source signal. In the receiver, a small planar antenna having a broad beam characteristic such as a single-element patch antenna is combined with an amplifier and a mixer circuit, which are formed on a micro planar circuit by an MMIC technique, so as to form a unit receiving circuit. A plurality of such unit receiving circuits are disposed on the receiver at intervals smaller than a wavelength corresponding to an IF band, and detection outputs from the unit receiving circuits are power-mixed. Thus, the receiver serves as a high-gain antenna having a detection function, and can realize a broad beam radiation characteristic comparable to that of a single-element antenna. The composed IF-band composite output is demodulated in an IF-band demodulation circuit. The present invention enables construction of a low-cost radio communication system, transmission of high-quality signals, and production of a wide beam antenna which has a high gain and which is convenient for use.

Millimeter-wave-band radio communication method in which both a modulated signal and an unmodulated carrier are transmitted to a system with a receiver having plural receiving circuits

A reference local oscillation signal transmission stationradiates a reference local oscillation signal to a service zone. A portion of the signal received by each radio slave station terminalis branched and fed to an injection locked oscillator. As a result, a local oscillation signal which is synchronized with the reference local oscillation signal is obtained. In the slave station terminal, the thus-obtained local oscillation signal is fed to a transmission frequency converter (mixer)and a reception frequency converter (mixer). An IF band transmission modulated signal is fed to the mixerfor frequency conversion to a radio frequency band, and the thus-obtained radio-frequency modulated signal is transmitted. Meanwhile, a received radio-frequency modulated signal is fed to the mixerfor down conversion, and the thus-obtained signal is fed to an IF band demodulatorso as to restore an information signal. The present invention not only solves the problem of deterioration of signal quality stemming from phase noise and frequency offset generated in a millimeter wave band oscillator, but also improves the efficiency of frequency use.

Radio communication method and system for performing communication among a plurality of radio communication terminals

A transmittertransmits from a transmission antennaa mixture signal containing a radio-frequency (RF)-band modulated signal, and a portion of power of a local oscillation signal used for frequency conversion. Meanwhile, a receiverdetects the transmitted signal by means of a reception antenna-detection section. In the reception antenna-detection section, a plurality of base unit reception circuitsare disposed. Each base unit reception circuitincludes a planar printed antennasuch as a patch antenna, an amplifier circuitformed on a very small planar circuit by means of an MMIC technique, and a mixer circuitserving as a square-law detector. Respective outputs of the base unit reception circuitsare power-mixed and fed to the IF signal demodulation section. The IF signal demodulation sectiondemodulate reception data. This configuration enables realization of a reception antenna which occupies a very small space, has a detection function and a high gain, and has a wide beam characteristic comparable to that of a single-element antenna.

Radio communicate method and system

A wireless communication system according to the invention is to perform communication with a terminal station at a radio frequency higher than a millimeter wave band. The wireless communication system includes, as transmission devices to the terminal station, a center station device which forms a baseband signal to the terminal station and a plurality of access point devices which receive delivered signals from the center station device and emit radio waves to the terminal station. Cover areas of the access point devices partially overlap to constitute a service area to the terminal station by all the cover areas. In this manner, a frequency higher than a millimeter wave band is applied to wireless communication to the terminal station to make it possible to widen the service area. When each of the access point devices has a configuration which simultaneously sends a transmission signal main body and a local oscillation signal of a radio frequency and the terminal station has a configuration which perform a square-law detection to a synthesized signal of the received transmission signal main body and the local oscillation signal, the terminal station can obtain a demodulated signal which is free from a frequency offset and a phase fluctuation of the local oscillation signal and which is reduced in doppler frequency.

This invention includes a wireless transmitter comprising an IF-signal generator that modulates input signals into those of an intermediate frequency band, signal distributors that distribute signals from the IF-signal generator, and a plurality of signal-transmission units that convert the signals distributed by the signal distributors into those of a radio frequency band, and then transmit the converted radio signals. The invention also includes a wireless receiver that receives the radio-frequency-band modulated signals and restores the signals of the intermediate frequency band. In this way, effective diversity is realized and signal interruptions are prevented. In addition, a handy, low-cost wireless communications system is provided.

Wireless communications system, wireless transmitter, and wireless receiver

Only a first radio station is equipped with a local oscillation signal source. A signal transmitted to a second radio station includes local oscilaation signal components used to up-convert a modulated intermediate frequency band signal in addition to intermediate frequency band signal components. The second radio station that receives the signal from the first radio station extracts and regenerate the local oscillation signal used at the first radio station using a local oscillation signal regenerator. The extracted and regenerated local oscillation signal is used to down-convert modulated radio signal components to the intermediate frequency band and simultaneously up-convert to the radio frequency band the modulated intermediate frequency band signal to be transmitted to the first radio station.

Two-way radio communication system and two-way radio communication method

In a radio communication apparatus and method, on the transmitting side, an input signal is modulated in an intermediate frequency band to produce a modulated intermediate frequency band signal, a local oscillation signal is used to up-convert the modulated intermediate frequency band signal to a modulated radio frequency band signal, and the local oscillation signal and the modulated radio frequency band signal are simultaneously transmitted as a radio signal, and, on the receiving side, the radio signal from the transmitter is received, the received signal is down-converted by multiplying the local oscillation signal component and the modulated radio frequency band signal component contained in the received signal to generate a multiplication component and thereby produce a modulated intermediate frequency band signal, and the modulated intermediate frequency band signal is demodulated.

Growing community of inventors

Tokyo, Japan

Yozo Shoji