Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Tohoku University

Fumio Ishizu

Keishi Murakami

Kenji Itoh

Ryoji Hayashi

Hiroaki Nagano

Takatoshi Katsura

Mitsuru Mochizuki

Yoshinori Matsunami

Shinjirou Fukuyama

Akinori Taira

Noriyuki Fukui

Shigenori Tani

Yasushi Sogabe

Mitsuhiro Shimozawa

Akinori Fujimura

Tadashi Takagi

Kouji Ueda

Kazuo Tsubouchi

Hiroyuki Nakase

Suguru Kameda

Shoichi Oshima

The number of communication channels necessary for communication with a terminal is calculated by using type and volume of data to be transmitted. When calculated number of communication channels is one, a single communication channel is allocated based on quality information of a communication line to the terminal and, when calculated number of communication channels is more than one, then more than one communication channels are allocated based on the quality information. Allocation information used for notifying of allocated communication channels is generated based on virtual channels, which are defined in advance as channel units having a combination of a plurality of consecutive communication channels, and the allocation information is transmitted to the terminal.

Channel allocation notifying method, communication method, and communication apparatus

A transmission device () includes: a series/parallel converter (); an MSK modulator () for modulating a signal on a channel basis; a D/A converter (); a frequency converter () for conversion into different carrier frequencies; a synchronization circuit (); an amplifier (); a multiplexer () for multiplexing amplification signals; and an antenna (). A reception device () includes: an antenna (); a demultiplexer (); a frequency converter () for converting signal demultiplexed on a channel basis into a baseband frequency; a low-pass filter () for removing a higher-harmonic component of the signal; an A/D converter (); a digital filter () for extracting a main wave component from the digital signal; a sampling point detection circuit () for detecting a sampling point from the main wave component; an MSK demodulator () for reproducing and demodulating a symbol point based on detection information by an interpolation process; and a parallel/series converter () for restoring an original signal from the demodulated signal.

Radio communication system

The number of communication channels necessary for communication with a terminal is calculated by using type and volume of data to be transmitted (Step S). When calculated number of communication channels is one, a single communication channel is allocated based on quality information of a communication line to the terminal and, when calculated number of communication channels is more than one, then more than one communication channels are allocated based on the quality information (Step S). Allocation information used for notifying of allocated communication channels is generated based on virtual channels, which are defined in advance as channel units having a combination of a plurality of consecutive communication channels, and the allocation information is transmitted to the terminal (Steps Sand S).

In a data transmission system, a transmitter adds control data to transmission data, and modulates the resultant signal by a predetermined modulation method, and sends the result in a wireless manner. A receiver detects a reception power intensity by use of the control data contained in the transmitted signal. A random pattern is used for a reception-power detecting portion for detecting a reception power intensity, which is contained in the control data.

Data transmission system, data transmitter and data receiver used in the data transmission system

A radio communication apparatus at a transmission side that includes a plurality of transmission antennas and performs a communication using at least one carrier. The radio communication apparatus includes a channel dividing unit configured to divide a transmission signal into a plurality of channels based on channel structure information returned from another radio communication apparatus at a reception side and indicating a structure of a space-division-multiplexing-channel and a space-time-coding channel between transmission and reception antennas, and a space-time-coding unit configured to realize transmission diversity by performing a space-time-coding processing for each of the plurality of channels.

Radio communication apparatus, transmitter apparatus, receiver apparatus and radio communication system

In a cellular telephone provided with a receiving circuit of a direct conversion type, a passive low-pass filter is arranged between a mixer for an I-channel and a base band circuit for removing interference waves of or above a channel next to a channel neighboring to the I-channel, and another passive low-pass filter is arranged between a mixer for a Q-channel and the base band circuit for removing interference waves of or above a channel next to a channel neighboring to the Q-channel. Since the low-pass filters for removing the interference waves of or above the channel next to the neighboring channel are of a differential type, the circuit scale can be small, and the power consumption is small. Since the interference waves are removed by the passive low-pass filters and the active low-pass filters, only the desired channel can be reliably received.

Wireless terminal device

A level of a base band signal at an input side of a variable gain amplification circuit is detected by a logarithmic amplifier having a wide input voltage range at a start of an operation, a control unit then performs a coarse feedforward control on a gain of the variable gain amplifier based on the detected level and finds a level of an output of an A/D converter by a mean square deriving circuit and inputs the resulting signal to the control unit. Then the control unit performs a fine feedback control on the variable gain amplifier based on the detected level.

A demodulator is constituted by: a clock recovery circuit for generating a recovered clock from the series of received data and outputting the recovered clock; a state estimation circuit for making an estimation about a reception state such as waveform distortion or the like from the series of received data, and outputting waveform information based on the result of the estimation; and a correlator for correcting a reference and/or sample points on the basis of the recovered clock and the waveform information, obtaining a correlation value between the series of received data and the reference from a plurality of the sample points, and outputting demodulated data on the basis of the correlation value.

Demodulator, clock recovery circuit, demodulation method and clock recovery method

The multicarrier transfer system employing the OFDM/CDMA modulation system comprises a transmitter having an S/P converter which two-dimensionally arranges spread signals for a transmission data array on a frequency and time axes system and then rearrange the spread signals for one transmission data array arranged two-dimensionally. The transmitter transmits the signals generated in the S/P converter. A receiver receives the signals transmitted by the transmitter and demodulates the signal to reconstruct the transmission data array.

Multicarrier transfer system and multicarrier modulation method

In a cellular telephone having a receiving circuit of a direct conversion type using an even harmonic orthogonal mixer, high-pass filters for removing a DC offset component are arranged before and after a variable gain amplifier in a base band circuit. The DC offset component occurred in the even harmonic orthogonal mixer is always constant, and the DC offset component occurred in the variable gain amplifier frequently varies so that a cutoff frequency of the front high-pass filter is set to be lower than a cutoff frequency of the rear high-pass filter, and the frequencies are set to achieve a fast transition response.

At the onset of an operation, a level of a base band signal at an input side of a variable gain amplifying circuit is detected by a logarithmic amplifier having a wide dynamic range, and, a control unit controls a gain of a low-noise amplifier in a previous step of a low-pass filter based on the detected level and also controls a gain of variable gain amplifier, whereby saturation at an analog base band portion is prevented even when the level of the input signal is high.

Growing community of inventors

Tokyo, Japan

Fumio Ishizu