Nec Corporation

Nippon Electric Co., Ltd.

Lenovo Innovations Limited (hong Kong)

Lenovo Innovations Limited

Masaki Ichihara

Yukitsuna Furuya

Michio Nagai

Shigeo Yoshihara

Tsuguo Maru

Yusuke Kimata

Kozo Maemura

Satoshi Niwa

This invention includes a waveform analyzing means () for calculating an estimated value of a back-off value required by a power amplifier (), which amplifies a high-frequency signal generated from a baseband signal (I, Q) to a predetermined transmission power, by analyzing the waveform of the baseband signal (I, Q), and a control means () for controlling at least one of the amplitude of high-frequency power input to the power amplifier () and the supply power of the power amplifier () on the basis of the estimated value. The invention calculates the estimated value of a back-off value by analyzing the waveform of a baseband in this manner, and hence need not generate a table in advance by calculating a back-off value for each combination of code channels. The invention can therefore be applied to even a case in which the number of code channels greatly increases, and can effectively prevent an increase in adjacent channel leakage power due to a signal obtained by multiplexing these code channels.

Distortion control device and method

A mobile communication system comprises a server, a cellular phone and a computer. The server sends/receives data through a network. The cellular phone downloads data to be used by itself, which is stored in the server. The computer transmits data to be used by the mobile communication terminal to the server. A user of the cellular phone updates or inputs data to be installed in the cellular phone from the computer. The data can be downloaded from the computer to the cellular phone.

Server, mobile communication system, and data updating method in the same

An OFDM receiving device for settling a problem of complicated configuration is provided, in that the OFDM receiving device receives an OFDM signal where no smaller than one specific sub-carriers among plurality of sub-carriers are modulated by a known modulation signal s(t), and includes a converting means for converting the received OFDM signal into the received signals for each sub-carrier, an extracting means for extracting the ingredient caused by a frequency drift and a phase noise based on received signal r(t) of the specific sub-carrier and the known modulation signal s(t), and a compensating means for H) compensating the received signal of the sub-carrier using the extracted ingredient.

OFDM receiving device and OFDM 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

Input average levels and output average levels of digital channel filtersandare computed in amplitude calculation circuitsand. In a gain difference calculation circuit, a gain difference of the input levels and the output levels is computed as a multiplier &#x3b1; so that a difference between the input levels and the output levels are eliminated or adjusted to be within a certain value. The outputs of the digital channel filtersandare multiplied by the multiplier &#x3b1; in multiplier unitsand. The multiplication results are outputted as corrected digital signals to a subsequent digital signal processing circuit.

Receiving amplitude correction circuit, receiving amplitude correction method, and receiver using the same

Reception levels are measured in respective branches to compare the results of the measurements with one another to select the result of the measurement of a maximum reception level which is the highest reception level. The gains of variable gain amplifiers () of all the branches including variable gain amplifiers () included in a branch corresponding to the maximum reception level are adjusted to the same value such that output levels of the variable gain amplifiers () are set to a preset target level.

Diversity receiver and gain adjusting method therefor

A multi-band wireless transceiver having a plurality of signal-processing paths, and further having a function of making wireless communication through a plurality of frequency bands by selecting one of the signal-processing paths, includes a band identification circuit for identifying a frequency band, the band identification circuit identifying a frequency band in dependence on a frequency-band information received from a controller which controls an operation of the multi-band wireless transceiver, and selecting one of the signal-processing paths in accordance with the identified frequency band.

Multi-band wireless transceiver and method of controlling the same

Variable gain circuits 16A and 16B are provided, respectively, on an output side of spreading circuits 15A and 15B disposed for each code channel, and after the outputs from the variable gain circuits 16A and 16B are added by adders 17 and 18, orthogonal modulation is applied to the outputs by a modulator 20, and a transmission signal is obtained. Furthermore, a variable gain circuit 22 for adjusting a level of the transmission signal is provided. An adjustment of average transmission power of the code channels is conducted by the variable again circuit 22, and an individual adjustment is conducted by the variable gain circuits 16A and 16B.

Method and apparatus for adjusting transmission power of CDMA terminal

A geomagnetic sensor for detecting geomagnetism is provided in a mobile terminal device. The output value of the geomagnetic sensor is compared with a first set value that has been set in advance, and the mobile terminal device is determined to be stationary when the output value of the geomagnetic sensor continues to be smaller than a first set value for at least a first set time period that has been set in advance, and the mobile terminal device is determined to be moving when the output value of the geomagnetic sensor fluctuates by at least the first set value. The determination results are transmitted to the base station, and the base station decreases the number of times for executing a process of registering the position of the mobile terminal device to the base station when the mobile terminal device is stationary, and increases the number of times of executing the process for registering position when the mobile terminal device is moving.

Mobile terminal device and positional information system

A base band circuit of a receiver and a low cut-off frequency control means can quickly converge transition state due to gain fluctuation with setting a low cut-off frequency of a high-pass filter as low as possible. The base band circuit of a receiver has a variable amplifier variably amplifying a base band signal depending upon a gain control signal, a high-pass filter provided in a path of the base band signal, and a controller detecting variation magnitude of the gain control signal and controlling variation of a low cut-off frequency of the high-pass filter means depending upon the detected variation magnitude.

Base band circuit of receiver and low cut-off frequency control method

In order to always maintain a frequency of an oscillator within a proper range, the frequency chages due to temperature and a secular change, a method is disclosed in which the secular change is calculated from past control information, and the frequency of the oscillator is corrected according to the secular change. A storing unit records the past control information for the oscillator. A processing unit calculates the secular change of the frequency of the oscillator from the past control information. Thereafter, the processing unit gives the oscillator new control information for correcting the calculated secular change.

Frequency correction method and apparatus for correcting secular change

A novel amplitude deviation correction circuit which corrects an amplitude deviation between an I signal and a Q signal is disclosed. An average amplitude deviation between an I signal amplified by a variable gain amplifier and a Q signal amplified by another variable gain amplifier is detected by an amplitude comparison circuit, and +1 volt or &#x2212;1 volt is outputted in response to a result of the detection. An integration circuit integrates the output of the amplitude comparison circuit and controls the gains of the variable gain amplifiers in response to a result of the integration.

Amplitude deviation correction circuit

A base band circuit forms a part of an automatic gain controller incorporated in a direct conversion receiver, and includes a series of variable gain amplifiers controlled by a gain controller and a feedback loop connected between the output node and the input node of the series of variable gain amplifiers, wherein the feedback loop has an attenuation circuit connected between the output node of the series of variable gain amplifiers and an inverted integrating circuit which, in turn, is connected through an adder and a low pass filter to the input node of the series of variable gain amplifiers so that direct current offset voltage is eliminated from the output signal of the series of variable gain amplifiers without change of cut-off frequency.

Growing community of inventors

Tokyo, Japan

Masaki Ichihara