Fujitsu Corporation

Morihiko Minowa

Tokuro Kubo

Noriyuki Kawaguchi

Dai Kimura

Kensuke Sawada

Satoshi Nakamura

Sadao Takenaka

Yoshihito Aono

Takanori Iwamatsu

Kazuhisa Obuchi

Hiroshi Nakamura

Yoshihiko Asano

Tetsuhiro Futami

Yoshimasa Daidoh

Kazuo Nagatani

Tsuyoshi Shimomura

Koji Matsuyama

Nobutsugu Fujino

Tadashi Nakamura

Tamio Saito

Yoshimasa Daido

Toshiaki Sakane

Tokurou Kubo

Masatsugu Takeuchi

A phase error detector in a base transceiver station detects a phase error caused by a Doppler shift in a received wave from a mobile station. A phase rotator rotates a phase of a transmission symbol in a base band region so as to cancel the Doppler shift, which occurs in a downlink from a base transceiver station to a mobile station based on the phase error detected by the phase error detector.

Mobile communication system, and base transceiver station apparatus and mobile station apparatus used in mobile communication system

The invention relates to an apparatus and a method for estimating a fading frequency of incoming received waves in a receiving station of a radio communication system or radio transmission system. An object of the invention is to estimate a fading frequency efficiently and accurately without substantially complexing the configuration of the system. To this end, the invention provides an apparatus for estimating a fading frequency from a pilot signal in a reception signal, which includes a calculation unit for calculating a magnitude of a complex product of two symbols that are received at different instants, and an estimation unit for estimating a fading frequency according to the calculated magnitude of the complex product.

Apparatus and method for fading frequency estimation

In a channel estimating circuit, a Sync Word is demodulated by using a channel estimation value not with a symbol or a slot including the Sync Word to be demodulated, but with its preceding and succeeding symbols or slots. Furthermore, in a channel estimation process, if a Synch Word to be demodulated is included in any of groups into which a plurality of symbols are divided, the Sync Word is demodulated by using a channel estimation value obtained with the channel estimation process using not this group but another group.

Synchronization detecting apparatus

An input signal includes spread signals which are respectively transmitted over a plurality of channels. First and second despread demodulators demodulate the spread signals transmitted over first and second communications channels by despreading them with first and second spread codes, respectively. A path detector generates a timing signal for instructing the timing at which the despread demodulators perform the despread operation. The path detector is shared by the first and the second despread demodulators, and operates in a time-division manner.

Receiving device for use in CDMA communications

In a CDMA receiver for applying despread processing to direct wave or delayed waves that arrive via each path of multiple paths, applying synchronous detection processing to the despread signals obtained, combining the detection signals of respective paths and discriminating the received data on the basis of the combined signal, (1) a weighting unit provided for every path measures power of delayed received waves that arrive via its own path and, if the reception power is less than a set level (breakpoint level), subjects an output signal to weighting conforming to the reception power; (2) a RAKE combiner combines signals output from the weighting units of the respective paths; and (3) a data discrimination unit discriminates receive data based upon the output signal of the combiner.

CDMA receiver

An apparatus includes a plurality of received-signal registers which receive and store therein a plurality of respective received-signal sequences, a selector which selects one of the received signal sequences stored in the received-signal registers, at least one code register which stores therein a de-spreading-code sequence, a multiplication circuit which multiplies the selected one of the received-signal sequences by the de-spreading-code sequence, and a summation circuit which obtains a sum of results of the multiplication to obtain a correlation between the selected one of the received-signal sequences and the de-spreading-code sequence.

Apparatus producing continuous stream of correlation values

The invention relates to a radio receiver which receives reception waves modulated with a frame being a sequence of slots and reproduces transmission information that is distributed to the slots. An object of the invention is to increase the reliability of channel inference and improve the transmission quality without substantially altering a basic configuration. A radio receiver of the invention performs quasi-synchronous detection on reception waves modulated with a frame; determines an error in a sequence of first vectors and a sequence of second vectors as an average of deviations of particular symbol positions to be indicated by the sequence of first vectors indicating a sequence of words included in each slot in a signal space, and the sequence of second vectors indicating known information included in the slots; and compensates for the error in the signal space.

Radio receiver

In a transmission power control apparatus for measuring SIR, which is a ratio of a receive signal to an interference signal, and controlling transmission power of a mobile station in such a manner that the measured SIR will agree with a target SIR, a fading detector detects the rate of change in fading, a correction unit corrects the target SIR based upon the rate of change in fading, and a transmission power control command creation unit creates a command for controlling transmission power of the mobile station in such a manner that the measured SIR will agree with the corrected target SIR, and transmits this command. Further, a searcher detects multipath and the levels of signals that arrive via respective ones of the paths, a level-difference calculation unit calculates level differences between the paths, a correction unit corrects the target SIR based upon the level differences between the paths, and a transmission power control command creation unit creates a command for controlling transmission power of the mobile station in such a manner that the measured SIR will agree with the corrected target SIR, and transmits this command.

Transmission power control apparatus

This invention relates to a radio base station equipment and a mobile station equipment in a mobile communication system that operate as determination stations adapted for a predetermined navigation or associate with other radio base station(s) or mobile station(s) to radio-determine the location of a desired mobile station. The mobile communication system achieves a radio determination economically and reliably while flexibly adapting itself to the substantial traffic distribution and transmission characteristics in individual wireless zones as well as the zone configuration, channel allocation, the procedure of channel control, and the structure of hardware.

Radio base station equipment and mobile station equipment determining location of mobile station by associating with another radio base station or mobile station in a mobile communication system

When an antenna receives a signal, the signal is inputted to delayers through a frequency converter, A/D converters, quadrature demodulators, filters and simultaneously is inputted to a MUX. The receiving signal inputted to the MUX is transmitted to an interference canceler panel, and the interference canceler panel generates both an interference replica signal and a symbol replica signal. The interference canceler panel demodulates the receiving signal for a channel corresponding to the symbol replica signal using both the interference and symbol replica signals. The interference replica signal generated by the interference canceler panel is transmitted to a transmitting/receiving panel and is inputted to interference elimination units. The interference elimination units eliminates interference components by subtracting the interference replica signal from the receiving signal delayed by the delayers and transmits the signal to a baseband signal processing panel.

Code division multiplex radio equipment with interference canceler

A searcher for a CDMA receiver apparatus includes a correlator obtaining a correlation value between a spreading code sequence and a spreading code sequence within a received signal, and a non-linear processor carrying out a non-linear conversion to convert one of the correlation value and a predetermined value indicative of the correlation value into correlation value information which has a data width smaller than that of the one of the correlation value and the predetermined value. The correlation value information is used to carry out a search process to search for a synchronizing timing with respect to the spreading code sequence within the received signal.

Searcher for CDMA receiver apparatus

A communication control apparatus installed in a base station or a mobile station in mobile communications system estimates the relative moving speed of an opposing station, and adjusts the values of communication parameters for a searcher, a transmission power control unit, an absolute synchronous detector unit, etc. according to an obtained moving speed.

Apparatus and method for controlling communications based on moving speed

A mobile communication terminal receives a control command transmitted on a down-link from a base station and controls a transmission power so that a reception state on an up-link becomes approximately constant at the base station. The mobile communication terminal is provided with a moving speed inferring unit which infers a moving speed of the mobile communication terminal, and a transmission power controller which varies a varying width of the transmission power depending on the moving speed of the mobile communication terminal.

Mobile communication terminal and transmission power control method therefor

A speed estimation apparatus detects the change of a transmission power control command transmitted from a receiving station and estimates the moving speed of the receiving station in mobile communications of a spread spectrum system. The speed estimation apparatus also generates a desired signal power by extracting a desired signal from received signals and estimates the moving speed of a corresponding transmitting station using the desired signal power.

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Kawasaki, Japan

Morihiko Minowa