Nec Corporation

Nippon Electric Co., Ltd.

Kokusai Denshin Denwa Co., Ltd.

Lenovo Innovations Limited

Yukitsuna Furuya

Masaki Ichihara

Kazuhiro Okanoue

Akihisa Ushirokawa

Hideho Tomita

Toshifumi Sato

Masanori Taketsugu

Toshihito Kanai

Junji Namiki

Fumio Akashi

Masahiro Ooki

Kojiro Hamabe

Shuji Murakami

Masahiro Ohki

Soichi Tsumura

Yoshihiko Akaiwa

Kazutomo Kobayashi

Katsuhiro Nakamura

Yoshio Matsuo

Yasuo Hirata

Yutaka Yasuda

There are obtained a transmitting apparatus capable of easily notifying information regarding radio waves required for an objective apparatus, a communication apparatus or a receiving apparatus capable of easily setting a frequency required at each place. a communication system or a broadcast receiving system employing the transmitting apparatus, the communication apparatus, and the receiving apparatus; and a control program, a communication method, and a broadcast receiving method to be used in the communication apparatus or the receiving apparatus. The radio wave towertransmits not only radio waves for the television and the radio, but also the radio wave informationfor communication and for reception of broadcasts by use of the radio wave information transmitting apparatus. For example, the portable terminalfirst receives the radio wave informationin a new place and then obtains a center frequency based on the information for communication with the base station. This also applies to television and radio frequencies.

Transmitting apparatus, communication apparatus, receiving apparatus, communication system, broadcast receiving system, control program, communication method and broadcast receiving method

To provide an orthogonal frequency division multiplex modem circuit which can multiplex signals, whose bit rates and QoS are different from one another, and can transmit the signals via one OFDM line. A serial/parallel converter converts input signals into a complex parallel signal respectively, and a sub carrier and a modulation system are assigned every communication channel. A randomizer changes the alignment sequence of the signal, a discrete inverse Fourier transformer processes the signal, a parallel/serial converter converts the signal into a serial signal, and a transmitter performs the orthogonal modulation of the signal to output the signal from an antenna. A receiver performs orthogonal demodulation of the signal received with an antenna, a serial/parallel converter converts the signal into a parallel signal, and a discrete Fourier transformer processes the parallel signal. In addition, a de-randomizer restores the alignment sequence of the subcarriers into the original condition, and a parallel/serial converter decodes and outputs the signal.

Orthogonal frequency division multiplex modem circuit

A system for efficiently utilizing a transmission capacity without complicated processing a hierarchical code comprised of a plurality of layers having different error correcting capabilities. In a transmitter, an encoding unit encodes an image in accordance with a hierarchical coding scheme to generate a plurality of layer data. An error correcting code addition unit performs error correction coding on each of at least one layer data including the lowermost layer data in accordance with an error correction coding scheme which gives higher error correcting capabilities to a lower layer than a higher layer. A transmission unit transmits each of the layer data and error correcting codes onto a transmission path. A receiver corrects possible errors introduced on the path into the layer data received from the transmitter according to the error correction coding scheme, and decodes layer data received in a quality available for decoding to restore the image.

Image communication system using a hierarchical code comprised of a plurality of layers

In a transmission side, a k-bit parallel signal is divided into n signals, which are respectively encoded and then phase-shifted so as to causing a mutual phase difference of &pgr;/2 . Spectrum spreading is performed on the phase-shifted encoded signals which are combined together to produce a transmission digital signal. In a receiving side, reverse spreading is performed on a receiving signal to produce reverse-spread signals, which are given the phase difference to cancel the phase shift of the transmission side, and then decoded. Thus, the original k-bit parallel signal is reproduced in the receiving side.

Radio data communication system using spread spectrum scheme

In a transmission diversity system for selecting one of a plurality of radio transmission systems in a base station to perform diversity transmission of data to a mobile station, the base station adds transmission data and identification signals different in the plurality of radio transmission systems to transmit resultant radio signals from the plurality of radio transmission systems, and transmits transmission data from one radio transmission system based on optimal radio transmission system information transmitted as a radio wave from the mobile station. The mobile station determines an identification signal representing an optimal reception state from the plurality of identification signals detected from the data received from the plurality of radio transmission systems of the base station and transmits the determined optimal radio transmission system information to the base station.

Transmisson diversity system

In a spread spectrum device including a serial to parallel converter (14) for converting a serial information signal (10) into a parallel signal of n bits, where n represents an integer not smaller than two, an information modulator (20) carries out information modulation on m bits among the n bits of the parallel signal and produces a modulated information signal, where m represents a positive integer smaller than n. A selective spreading code producing circuit (21, 22) has spectrum spreading codes which are equal in number to 2.sup.(n-m) and are different from one another. The selective spreading code producing circuit selectively produces, as a selected spreading code, one of the spectrum spreading codes that is specified by remaining (n-m) bits among the n bits of the parallel signal. A spectrum spreading circuit (23) carries out spectrum spreading on the modulated information signal on the basis of the selected spreading code and produces a spectrum spread signal (13). The spectrum spread signal may be transmitted by a radio portion (18) as a radio information signal (11).

Spread spectrum method for transmitting an information signal as a radio

In a base station transmitter/receiver of a cellular system, a plurality of antennas are oriented in each sector and radiate radio transmission signals and receive radio reception signals to produce received signals. A signal processing circuit is connected to the antennas to process the received signals into output reception signal and to process input transmission signal into the radio transmission signals in response to the received signal. Thus, the signal processing circuit serves to vary the directivities of the antennas in each sector and to thereby control a composite directivity formed by the varied directivities.

Base station transmitter/receiver capable of varying composite

It is an object of the present invention to provide a base station transmission-reception apparatus wherein an increase in the number of sectors does not increase the load to a control center arising from hand-over between sectors and does not increase the number of processing sections for each channel. In the apparatus, each of baseband signal processing sections 1-1 to 1-N includes a transmission signal selection circuit 202 for outputting a transmission signal from a transmission signal processing section 201 to only a sector antenna 107 indicated by a selection signal, a reception signal selection circuit 204 for selecting a reception signal of a sector indicated by the selection signal, a reception signal processing section 203 for detecting reception data corresponding to its own communication channel from the reception signal from a reception signal selection circuit 204, and a control section 207 for providing the selection signal to the transmission signal selection circuit and the reception signal selection circuit.

Base station transmission-reception apparatus for cellular system

In a variable modulation communication method, the transmission quality of a transmission path is monitored. If the transmission quality is good, communication is performed while the transmission time is shortened by using a multilevel modulation scheme. If the transmission quality is bad, communication is performed while the transmission time is prolonged by using a modulation scheme having a smaller number of levels than the multilevel modulation scheme. A variable modulation communication apparatus is also disclosed.

Variable modulation communication method and system

A maximum likelihood sequence estimation apparatus decodes a digital data signal. The apparatus includes: a sampling device to perform sampling and to output a received signal by sampling pulses having a constant time interval T and N different sampling phases; an operation device to operate a branch metric of the received signal sampled by the N different sampling phases; and a device to perform maximum likelihood sequence estimation of the branch metric.

Maximum likelihood sequence estimation apparatus

A half duplex radio communication system having including a plurality of terminal equipments and a base station for relaying communications between the terminal equipments is characterized by, in each of the terminal equipments, transmitting a transmission right demand signal upon initiation of transmission and a transmission end signal upon termination of transmission. The base station is responsive to the transmission right demand signal from the terminal equipment for assigning a transmission channel, and is responsive to the transmission end signal for releasing the channel assignment and for assigning the transmission channel for the terminal equipment newly obtaining the transmission right.

Half duplex communication system having quick channel assignments

In a TDMA cellular mobile communication system, incoming signals from the public switched network are converted by speech coder/data compressor units of a MTSO (mobile telephone switching office) to low-bit-rate signals and combined into a first TDM signal for transmission to a base station. The components of the first TDM signal are respectively routed according to a channel assignment signal and fed into desired modulators which are periodically activated according to the channel assignment signal to transmit signals on assigned channels to mobile units. Signals from the mobile units are received by demodulators at the base station and combined into a second TDM signal which is transmitted to the MTSO. The components of the second TDM signal are routed according to the channel assignment signal to appropriate speech decoder/data expander units for conversion to the original high-bit-rate signals for transmission to the network.

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Tokyo, Japan

Yukitsuna Furuya