Ntt Mobile Communications Network, Inc.

Yozan Corporation

Other

Ntt Docomo, Inc.

Nippon Telegraph and Telephone Public Corporation

Renesas Electronics Corporation

Nippon Telegraph and Telephone Corporation

Intelligent Cosmos Research Institute

Fumiyuki Adachi

Mamoru Sawahashi

Changming Zhou

Guoliang Shou

Tomohiro Dohi

Makoto Yamamoto

Sunao Takatori

Xuping Zhou

Yukihiko Okumura

Sadayuki Abeta

Akihiro Higashi

Koji Ohno

Kenichi Higuchi

Takeshi Hattori

Hiroyuki Atarashi

Seizo Onoe

Yasushi Yamao

Shinji Uebayashi

Shogo Ito

Akihiro Maebara

Takehiro Ikeda

Kunihiko Suzuki

Koichi Okawa

Jie Chen

Shinzo Ohkubo

Masaharu Hata

Kenkichi Hirade

Xiaoling Qin

Syunsuke Seo

Hidehiro Andou

Kobaruto Shimada

Toshinori Fujii

Yukihiko c/o Ntt Docomo Inc Okumura

Akihiro Hayashi-Syataku 3-301 Higashi

Koji Tomioka-Syataku 8-502 Ohno

A spread spectrum clock generator includes: a phase comparing unit that receives a reference clock signal and a feedback clock signal, and generates a control voltage corresponding to a phase difference between the reference clock signal and the feedback clock signal; a voltage-controlled oscillator that oscillates at an oscillating frequency corresponding to the control voltage, and generates an output clock signal; a delta-sigma modulator that receives a waveform signal for controlling spreading of a spectrum of the output clock signal, and outputs bits larger than 1 bit based on the waveform signal; a control circuit that controls a multiplication number according to an output signal of the delta-sigma modulator; and a divider that generates the feedback clock signal by dividing the output clock signal according to the multiplication number controlled by the control circuit, and supplies the feedback clock signal to the phase comparing unit.

Spread spectrum clock generator

A spread spectrum clock generator includes: a phase comparing unit that receives a reference clock signal and a feedback clock signal, and generates a control voltage corresponding to a phase difference between the reference clock signal and the feedback clock signal; a voltage-controlled oscillator that oscillates at an oscillating frequency corresponding to the control voltage, and generates an output clock signal; a delta-sigma modulator that receives a waveform signal for controlling spreading of a spectrum of the output clock signal, and outputs bits larger than 1 bit based on the waveform signal; a control circuit that controls a multiplication number according to an output signal of the delta-signal modulator; and a divider that generates the feedback clock signal by dividing the output clock signal according to the multiplication number controlled by the control circuit, and supplies the feedback clock signal to the phase comparing unit.

A communication technology for allowing a mobile communication system to accommodate variable rate users, while obtaining a frequency diversity effect. A transmitter apparatus using, for transmission, transmission signals produced based on data symbols of a predetermined transmission method, comprising an FFT processing part for converting the data symbols to frequency domain data; an interleaver for sorting the frequency domain data; and an IFFT processing part for converting the sorted frequency domain data to a time domain signal; wherein the FFT processing part subjects Q received data symbols to Q-point FFT processing, the interleaver produces N data from Q data outputted from the FFT processing part (where N&#x3e;Q), and the IFFT processing part subjects the N data outputted from the interleaver to N-point IFFT processing.

Transmitter apparatus, communication system, and communication method

The present invention provides a single carrier/DS-CDMA packet transmission method wherein a predetermined time slot is assigned to reservation demand packet transmission in regard to a spreading code, and the reservation demand packet and data packets are time-multiplexed for transmission. An uplink packet transmission method in a multi-carrier/DS-CDMA mobile communication system is also provided, wherein frames are set up in each communication channel of a subcarrier, time slots which are time-segments of the frames are set up further, and a mobile station spreads a packet to be transmitted by a spreading code and the information signal is transmitted to a base station in a predetermined time slot. A downlink channel configuration in a multi-carrier/DS-CDMA mobile communication system is further provided, wherein a plurality of communication channels assigned to each of a plurality of subcarriers are divided for every predetermined time frame, and multiplexed, and the plurality of the communication channels assigned to each subcarrier include a common-control channel used by a plurality of users in common, and communication channels peculiar to each user.

Single-carrier/DS-CDMA packet transmitting method, uplink packet transmitting method in multi carrier/DS-CDMA mobile communication system, and structure of downlink channel in multi carrier/DS-CDMA mobile communication system

A CDMA receiver and a CDMA transceiver are provided which have high resistance to fading fluctuations, and carry out highly accurate channel estimation, considering the rate of channel fluctuations. When carrying out the channel estimation by calculating weighted sums of the (average values of) pilot symbols interposed into a data symbol sequence, the weighting control is performed considering the rate of the channel fluctuations. For example, the weighting control is carried out using, as its update values, inner products of the channel estimation values and the (average values of) pilot symbols. This makes it possible to achieve the highly accurate channel estimation.

CDMA receiver and CDMA transmitter/receiver

There are provided a channel estimation unit for achieving highly accurate channel estimation, a CDMA receiver and a CDMA transceiver with the channel estimation unit. Channel estimates of data symbols are obtained from pilot symbols in a combined symbol sequence which has a plurality of slots and includes the data symbols and the pilot symbols. First, the pilot symbols in the combined symbol sequence are located. Second, pilot blocks are generated by extracting the pilot symbols from two or more slots in the combined symbol sequence. Third, channel estimates of the data symbols are obtained by calculating a weighted sum of averages of the pilot symbols in the individual pilot blocks. The weighted sum is carried out using appropriate weighting factors for individual data symbols in each slot. This enables highly accurate channel estimation.

Channel estimation unit, and CDMA receiver and CDMA transceiver with channel estimation unit

A transmission method for implementing variable rate transmission. Part of the baseband processing of a transmitter based on a CDMA transmission scheme is described. A transmitted information sequence in the form of a digital signal is phase modulated by a phase modulator . An orthogonal code generator selects, in response to rate information of the transmitted signal, the orthogonal code to be generated. The bit rate of the orthogonal code the orthogonal code generator generates is double the maximum transmission rate. The modulated transmitted signal is multiplied by the orthogonal code corresponding to the rate information with a multiplier . The transmitted signal, which is multiplied by the orthogonal code corresponding to the rate information, is further multiplied by a spreading code sequence with a multiplier to be spread into a CDMA signal, and is transmitted under power transmission control based on the rate information. A receiving side can detect the rate without information about the transmission rate.

Variable rate transmission and reception methods, and variable rate transmission and reception devices

There are provided a channel estimation unit for achieving highly accurate channel estimation, a CDMA receiver and a CDMA transceiver with the channel estimation unit. Channel estimates of data symbols are obtained from a pilot symbol sequence which is parallel with a data symbol sequence. First, a plurality of pilot blocks are generated from the pilot symbol sequence. The channel estimates of the data symbols are obtained by calculating a sum of appropriately weighted averages of pilot symbols in the individual pilot blocks. This enables highly accurate channel estimation. More accurate channel estimation can be achieved by carrying out the channel estimation of the data symbols using the pilot symbols belonging to other slots rather than limiting to the pilot symbols in the slot to which the estimated data symbol belongs.

A plurality of sets of spreading code sequences are stored in registers and selectively supplied to matched filters. The soft-handover, multi-code processing and long-delay paths can be processed by a small circuit.

Signal reception apparatus for DS-CDMA cellular system

A signal reception apparatus for DS-CDMA communication system having a complex matched filter for despreading a received signal into I- and Q-components D and D of despread signal. D and D are input to a path selection portion for extracting a phase error in a pilot symbol block of the despread signal. A phase compensation signal is calculated according to the phase error in the portion An information symbol is compensated according to the phase compensation signal. An electrical power is calculated from an average of the phase compensation signal of several slots for selecting paths to be received. The selected paths are combined with phase synchronized by a rake combiner

Signal reception apparatus for DS-CDMA communication system

A digital modulation and demodulation scheme for radio communications which is capable of reducing errors due to fading while maintaining the characteristic of the M-ary modulation and demodulation scheme that it is robust against interferences. At the transmitting side, transmission data are divided in advance into blocks of LN bits length each and each block is divided into N sets of L bits data sequences. Then, orthogonal codes of M bits length each corresponding to L bits codes given by the L bits data sequences are generated, and N sets of orthogonal codes for each block are multiplexed into a multiplexed signal, such that M bits constituting each orthogonal code are dispersed in time in the multiplexed signal. A digital modulation is then applied to a carrier using the multiplexed signal.

Robust digital modulation and demodulation scheme for radio communications involving fading

A signal reception apparatus in the spread spectrum communication system requires only a small amount of circuitry and consumes a small amount of electric power. A quadrature detector decomposes received signals into in-phase components and quadrature components, and supplies them to a complex-type matched filter. The complex-type matched filter de-spreads the in-phase components and the quadrature components and sends them to a multi-path selector. The multi-path selector selects, from among the received de-spread signals, multiple paths having high levels of signal electric powers and sends the received signals of the selected paths to multiple phase correction blocks. Analog operation circuits calculate phase errors of the received signals of two successive pilot symbol blocks for each path. An analog operation circuit corrects the phases of the received signals of the information symbol block that has been received between the two successive pilot symbol blocks. A rake combiner synchronously combines the phase-corrected de-spread received signals of each path.

Receiver in a spread spectrum communication system having low power analog multipliers and adders

An output of analog complex matched filter is simplified to be a one dimensional signal such as electrical power. Multi-path detection is performed by the simplified signal. The output of the matched filter is received and processed only when peaks occur in the one dimensional signal.

Receiver apparatus for CDMA communication system

The present invention provides a path-diversity system featuring a small-size phase compensating circuit. This circuit calculates a compensating coefficient according to the signals of a pilot block or a pair of pilot blocks surrounding an information block, and then compensates information signals thereafter by the calculated compensating coefficient.

Path-diversity receiving method and system of spread spectrum communication

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

Growing community of inventors

Yokohama, Japan

Fumiyuki Adachi