Ntt Mobile Communications Network, Inc.

Ntt Docomo, Inc.

Nec Corporation

Tomohiro Dohi

Mamoru Sawahashi

Fumiyuki Adachi

Koji Ohno

Narumi Umeda

Yukihiko Okumura

Sung Uk Moon

Toshiyuki Futakata

Syunsuke Seo

Hiroyuki Ishii

Toshifumi Sato

Shinji Uebayashi

Akihiro Higashi

Atsushi Fujiwara

Etsuhiro Nakano

Mayu Yamada

Takayuki Ishiguro

There is provided a control device enabling switching of communication of a mobile terminal with one system to communication with another system while reducing power consumption and workload of the mobile terminal. The control device is used in a communication system including a first mobile communication system, a second mobile communication system, and a mobile terminal being in communication with the first mobile communication system. The control device comprises a position measuring unit for measuring the position of the mobile terminal, a judgment unit for making a determination whether or not to switch the communication of the mobile terminal from the first mobile communication system to the second mobile communication system according to a position measurement result of the position measuring unit, and a switching unit for performing the above switching operation according to the determination of the judgment unit.

Control device of mobile communication system

There is provided a radio communication device able to adaptively adjust a pilot symbol insertion rate and improve efficiency of channel estimation and data transmission. It comprises a channel estimation unit that performs the channel estimation using the pilot symbols, a storage unit that stores a plurality of estimated values obtained by the channel estimation unit, a determination unit that compares the estimated values stored in the storage unit and determines an amount of change of the estimated values, and a notification unit that notifies the pilot symbol insertion unit of the amount of change of the estimated values.

Radio communication device and method thereof

An error rate of received signal is measured by a received signal error measuring unit , and a target SIR is changed by a target SIR decision unit using the error rate. It is also possible to detect error rate of received signal in an unit of frame using a CRC signal of a frame. It is further possible to detect error rate of received signal by detecting errors of known pilot signals inserted in a constant interval.

Power controller for mobile communication system wherein a signal to interference threshold is dynamically moved based on an error rate measurement

A coding and decoding system which uses CRC check bits is disclosed. When a coding apparatus performs coding, symbol interleaving is performed after coding by an outer code of a concatenated code, and coding by an inner code is performed after CRC check bits are added. Then, upon decoding by a decoding apparatus, error detection using the CRC check bits is performed after decoding of the inner code. After symbol deinterleaving is performed, decoding of the outer code by erasure decoding or error correction is performed depending upon the number of symbols included in a frame in which an error has been detected.

Coding and decoding system using CRC check bit

Method and instrument for measuring receiving SIR and transmission power

A transmission power control scheme for a mobile communication system for suppressing the transmission power to an absolutely necessary minimum level, and increasing the subscriber capacity by reducing an amount of interference. In this scheme, at a time of controlling a transmission power of each radio channel at one of the base station and the mobile station so as to make a difference between a target CIR and a reception CIR of each radio channel at another one of the base station and the mobile station smaller, the target CIR for all radio channels at that another one of the base station and the mobile station are set independently, and/or the target CIR for each radio channel is changed at that another one of the base station and the mobile station, according to a channel quality of each radio channel at either one of the base station and the mobile station.

Transmission power control apparatus and method in a mobile

A frequency correction device for a spread-spectrum communication receiver requiring no high-accuracy, high-stable VCO as a local signal oscillator. It includes a quasi-coherent quadrature detector detecting an intermediate frequency signal using a local signal from a fixed frequency local oscillator, a correlation detector producing a despread signal by demodulating the output of the detector, a clock signal generating portion generating a pair of clock signals whose frequency is deviated a little with respect to a clock signal for driving the correlation detector. The pair of clock signals are used to drive two correlation detectors, and the amplitude of the outputs of the correlation detectors are squared, and then subtracted, thereby generating a correlation output error signal. Since the correlation output error signal has one to one correspondence with the frequency difference between the chip frequency of the spread spectrum signal outputted from the quasi-coherent quadrature detector and the frequency of the clock signal, a frequency correction signal can be generated by converting the correlation output error signal into the frequency error. The frequency difference between despread signal and the clock signal, which arises from the difference between the center frequency of a received signal and the local signal, can be corrected by correcting the frequency of the despread signal by the frequency correction signal.

Frequency error correction device of a spread-spectrum communication

A communication apparatus is disclosed which is capable of measuring levels of carrier signals used in adjacent zones during telecommunication with a small circuit scale, and capable of simultaneously transmitting/receiving to FDMA-system signals through a plurality of communication channels. All of transmission signals received through the communication channels under use are wholly converted into an intermediate signal by a mixer. The intermediate signal is quadrature-detected and then A/D-converted into digital I/Q-channel signals by A/D-converters. Thereafter, the digital I/Q-channel signals are frequency-converted by frequency converting circuits in such a manner that center frequencies of these I/Q-channel signals become zero, two sets of I/Q-channel signals may be demodulated by two sets of demodulating circuits. Otherwise, one of these I/Q-channel signals is demodulated by a single demodulating circuit, and the other is level-detected by a level detecting circuit.

Communication system capable of performing FDMA transmission

Maximum likelihood differential detecting method and differential

Receiver and repeater for spread spectrum communications

Correlation detector and communication apparatus

A transmission power control method is disclosed for controlling transmission power of radio communications in a CDMA system. The transmission power of a first transmitted signal transmitted from a first station is determined by a transmission power control signal contained in a second transmitted signal sent from a second station. The first station receives the second transmitted signal in the form of convolutional codes, and decodes it by using a first Viterbi decoder and a second Viterbi decoder. The first and second Viterbi decoders includes path memories with the path history length of different first predetermined lengths. The transmission power control signal contained in the second transmitted signal is extracted from the output of the second Viterbi decoder, whereas the other information data is obtained from the output of the first Viterbi decoder. The first station controls the transmission power of the first transmitted signal on the basis of the extracted transmission power control signal.

Transmission power control method and apparatus for mobile

A transmission power control method of a spread-spectrum communication system which determines transmission power in accordance with a transmission power control bit. The transmission power control bit is extracted at a base station from a signal sequence obtained by receiving a signal transmitted from a mobile station, and by despreading and demodulating the received signal. When the same value of the transmission power control bit is consecutively received, the transmission power of the base station is controlled in accordance with transmission power control quantities which are predetermined in accordance with the consecutive number of receptions of the same value of the transmission power control bit. This is because the consecutive receptions of the same value of the transmission power control bit suggests that the received power of the other party (the mobile station in this case) changes greatly. Thus, an amount of an increment or a decrement in the transmission power is increased with the duration of the consecutive receptions. This makes it possible for the transmission power control to follow sudden changes in propagation paths.

Transmission power control method of a spread-spectrum communication

Spread spectrum communication receiver

A CDMA communications method capable of multiplex transmission of data over a wide range from a low rate to high rate such as image data without a considerable increase in a circuit scale. A fundamental transmission rate is determined, for example, at 32 kbps, a rate higher than 8 kbps conventionally used. The data whose transmission rate is equal to the fundamental transmission rate is transmitted in frames including no vacant portion. Data whose transmission rate is lower than the fundamental transmission rate (16 kbps, for example) is transmitted in frames including vacant portions. The vacant portions are not transmitted. This makes it possible to receive data through other channels during a time period associated with the vacant portions. Data of a higher transmission rate, 128 kbps, for example, can be multiplexed and transmitted through four channels using different spreading codes.

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Yokohama, Japan

Tomohiro Dohi