Ntt Mobile Communications Network, Inc.

Ntt Docomo, Inc.

Koji Ohno

Akihiro Higashi

Mamoru Sawahashi

Takehiro Nakamura

Etsuhiro Nakano

Hiroshi Kawakami

Motoshi Tamura

Seizo Onoe

Junichiro Hagiwara

Hiroki Morikawa

Masatomo Nakano

Fumiyuki Adachi

Yukihiko Okumura

Tomohiro Dohi

Narumi Umeda

Shinji Uebayashi

Koichi Okawa

Kenichi Higuchi

Takaaki Sato

Seizou Onoe

A base station including a transmitting and receiving amplifier for amplifying CDMA signals exchanged with a mobile station; a radio stage connected to the transmitting and receiving amplifier for carrying out D/A conversion of a transmitted signal that undergoes baseband spreading, followed by quadrature modulation, and for carrying out quasi-coherent detection of a received signal, followed by A/D conversion; a baseband signal processor connected with the radio stage for carrying out baseband signal processing of the transmitted signal and the received signal; a transmission interface connected with the baseband signal processor for implementing interface with external channels; and a base station controller for carrying out control such as management of radio channels and establishment and release of the radio channels. The base station communicates with the external channels by mapping logical channels into physical channels. The CDMA signals are spread using a short code and a long code.

Base station apparatus of mobile communication system

A DS-CDMA transmission method capable of improving the accuracy of channel estimation using pilot symbols by eliminating cross-correlation between pilot symbols inserted into code channels in CDMA multiplexing carrying out fast signal transmission. In each frame assembler, the pilot symbols, which are used for channel estimation for coherent detection, are inserted into coded information data on code channels at fixed intervals, and then the data is modulated by the modulator. The modulated data symbols in each code channel from the modulator are spread by the spreading modulator, the pilot symbols are spread using a spreading code, whereas the information symbols are spread using different spreading codes assigned to respective code channels. The spread signals of the code channels are summed up by the adder to be transmitted.

DS-CDMA transmission method

A base station including a transmitting and receiving amplifier for amplifying CDMA signals exchanged with a mobile station; a radio stage connected to the transmitting and receiving amplifier for carrying out D/A conversion of a transmitted signal that undergoes baseband spreading, followed by quadrature modulation, and for carrying out quasi-coherent detection of a received signal, followed by A/D conversion; a baseband signal processor connected with the radio stage for carrying out baseband signal processing of the transmitted signal and the received signal; a transmission interface connected with the baseband signal processor for implementing interface with external channels; and a base station controller for carrying out control such as management of radio channels and establishment and release of the radio channels. The base station communicates with the external channels using ATM cells, and with the mobile stations using the CDMA signals by mapping a plurality of logical channels into a plurality of physical channels. The CDMA signals are spreading using two types of spreading code sequences, that is, a short code and a long code.

Signal transmitting method, transmitter, receiver, and spread-spectrum

A RAKE receiver which is employed in a direct sequence spread spectrum communication system, and which can effectively receive multipath signals. A path searcher measures the amplitude of each path, selects N paths with larger amplitudes in descending order of magnitude, where N is the number of despreaders, and assigns the despreaders to the selected paths to despread the signals of the paths. This assignment of the despreaders to the paths is carried out such that a path with a large amplitude and a path with a small amplitude are assigned to adjacent despreaders and are input to the same pre-detection combiner. The outputs of the despreaders are combined by the pre-detection combiners, and detected by detectors whose outputs are RAKE combined by a post-detection combiner.

Rake receiver

A downlink transmission power control scheme for a mobile communication system using the site diversity, which carries out a primary downlink transmission power control using a primary control signal which is transmitted from the mobile station and terminated at each base station, and an additional downlink transmission power control using additional control signals which are transmitted from the base station control station to the base stations. The additional downlink transmission power control may also use a secondary control signal which is transmitted from the mobile station and terminated at the base station control station. The primary downlink transmission power control can be carried out during a non-site diversity period while the additional downlink transmission power control is carried out during the site diversity period, or the primary downlink transmission power control and the additional downlink transmission power control can be both carried out during the site diversity period.

Downlink transmission power control scheme for mobile communication

Variable rate transmission method, transmitter and receiver using the

Coherent detector and a coherent detection method for a digital

Receiver and repeater for spread spectrum communications

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

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Yokohama, Japan

Koji Ohno