Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Yuuri Yamamoto

Yoshinori Kunieda

Hiroshi Ohnishi

Kenichi Takahashi

Kouei Misaizu

Akihiko Matsuoka

Hidekuni Yomo

Naoki Matsubara

Mitsuo Makimoto

Hiroshi Onishi

Yoshihito Kawai

An A/D conversion section performs oversampling on an analog signal at a rate M times a symbol rate to convert the analog signal into a digital signal. A FIR filtering section has two delay-element sequences, each with a plurality of delay elements. The two delay-element sequences have different delay directions, i.e., a forward direction and a reverse direction. The delay directions can be switched, and according to a finite impulse response train having such delay-element sequences, a convolutional calculation is performed. A phase determining section determines a phase used in making a decision in a decision section. The decision section makes a decision on a filtered signal using the phase determined in the phase determining section to generate bit data. A digital signal receiving apparatus is thus achieved which determines a phase with a high accuracy without increasing the oversampling number, and performs a fast calculation while having a reduced circuitry scale.

Finite impulse response filter and digital signal receiving apparatus

A relay apparatus, terminal apparatus and relay method for relaying signals with a reduced scale of the apparatus, without temporally switching between transmission and reception and with reduced waste of time when relay is performed at the same frequency on a radio communication network on which bidirectional communication is performed. A radio reception sectionoutputs information signals to a switch, outputs relay control signals to a demodulation sectionafter subjecting predetermined radio reception processing. The demodulation sectiondemodulates a relay control signal. A relay control signal processing sectiondecides the possibility of relay of information signals and inquires, when the relay is possible, whether the terminal apparatus on the receiving side can receive this information signal or not. Furthermore, the relay control signal processing sectionconnects a switchduring the stored relay time. The switchis connected only the information signals to be relayed are received under the control of a relay control section

Relay apparatus, terminal apparatus and relay method

A receiving ckt for receiving a transmitted SIG including FRQ divided carriers, comprises: a FRQ conversion ckt responsive to the LO SIG with a LO for generating a LO SIG with LO FRQ controlled according to a FRQ CONT SIG for FRQ converting the transmitted SIG into an IF SIG; a orthogonal signal separation ckt separating the IF SIG into I and Q components; a complex FFT conversion ckt for complex FFT converting the I and Q components and outputting conversion SIGs to be decoded arranged in FRQ base; an ELEC PWR measurement ckt measuring values of ELEC PWRs of the conversion SIGs; and a prediction ckt for predicting a CTR FRQ of the FRQ divided carriers from a FRQ distribution of the values of ELEC PWRs from the ELEC PWR measurement ckt and generating the FRQ CONT SIG according to the predicted center FRQ. The CTR FRQ may be detected by a REF carrier detection ckt responsive to the complex FFT processing ckt detecting a REF carrier or a carrier pattern included in the transmitted SIG. A correlation between the conversion SIGs and a REF SIG having values varied every predetermined interval within a symbol period is detected to generate the FRQ CONT SIG, wherein a phase compensating ckt for compensating phase of the conversion SIGs in response to the FRQ CONT SIG may be provided.

Receiving circuit having a frequency compensated local oscillation

A timing signal generator includes a demodulator for an input modulated signal to provide first and second baseband signals having a quadrature relation relative to each other. A converter is used to convert the first and second baseband signals into angle data representing a phase, and a calculator is used to calculate a difference between the phase represented by current angle data and the phase represented by previous angle data, preceding the current angle data by a 1-symbol interval. The calculator outputs data representative of the calculated phase difference. A further converter converts the calculator output data into a binary reference signal responsive to which of predetermined divided regions contains a point corresponding to the calculated difference data. Also included is a generator for generating a symbol timing signal in synchronism with the binary reference signal.

Timing signal generator

In a frame synchronizing apparatus for a receiver apparatus of a digital data radio communications system in which data are transmitted in frame periods with a fixed data sequence contained each frame, a data correlation circuit obtains successive sequences of values of vector difference between vector values constituting a demodulated digital baseband signal, and successively compares these sequences with a fixed vector difference sequence corresponding to the fixed data sequence, to derive a correlation signal substantially unaffected by any phase rotation in the baseband signal. A frame synchronizing circuit formed as a PLL for generating a frame synchronizing signal, includes a phase comparator which periodically indicates whether a detected phase difference between the correlation signal and frame synchronizing signal is effectively zero, positive or negative, and a counter holding a count value indicating a cumulative phase error between these signals. So long as the detected phase differences are successively effectively zero and the cumulative phase error is sufficiently small, the phase of the frame synchronizing signal is held unchanged, thereby achieving a high degree of phase stability.

Frame synchronizing apparatus for quadrature modulation data

A complex angle converter includes a comparing device. The comparing device operates to derive first difference data representing a difference between predetermined reference data and data represented by a first baseband signal. The comparing device further operates to derive second difference data representing a difference between the predetermined reference data and data represented by a second baseband signal having a quadrature relation with the first baseband signal. The comparing device further operates for comparing absolute values of the first difference data and the second difference data, and for outputting a signal representative of a result of the comparing. The complex angle converter also includes a device serving to group an inversion of a highest bit of the first baseband signal and second highest and lower bits of the second baseband signal into a first set. An additional device serves to group a highest bit of the second baseband signal and second highest and lower bits of the first baseband signal into a second set. A selector operates to select one of the first set and the second set in response to the output signal of the comparing device. A decoder is included for decoding the highest bit of the first baseband signal, the highest bit of the second baseband signal, and the selected one of the first set and the second set into data representing a complex angle.

Complex angle converter

A quadrature demodulator includes a device for generating first and second reference signals having a quadrature relation with each other. A first demodulating device serves to compare phases of the first reference signal and an input modulated signal to demodulate the input modulated signal into a first binary baseband signal. A second demodulating device serves to compare phases of the second reference signal and the input modulated signal to demodulate the input modulated signal into a second binary baseband signal having a quadrature relation with the first baseband signal. A first counting device operates to count pulses of a clock signal in response to the first baseband signal. A second counting device operates to count pulses of the clock signal in response to the second baseband signal. An address signal is generated in response to the output signals of the first and second counting devices. Data representative of an absolute phase of the input modulated signal is generated in response to the address signal.

Quadrature demodulator

A diversity receiver includes a first antenna and a second antenna. A first receiving section connected to the first antenna serves to convert a digital modulation wave induced at the first antenna into a first intermediate-frequency signal. A first band pass filter connected to the first receiving section serves to subject the first intermediate-frequency signal to a band pass filtering process. A second receiving section connected to the second antenna serves to convert a digital modulation wave induced at the second antenna into a second intermediate-frequency signal. A second band pass filter connected to the second receiving section serves to subject the second intermediate-frequency signal to a band pass filtering process. A switch alternately selects one of output signals of the first and second band pass filters at a period equal to a half of a period corresponding to the symbol rate. A quadrature demodulator connected to the switch serves to demodulate an output signal of the switch into quadrature baseband signals. An analog-to-digital converter connected to the quadrature demodulator converts the quadrature baseband signals into corresponding digital signals. A decision feedback adaptive equalizer connected to the analog-to-digital converter serves to subject the digital signals to an equalizing process.

Diversity receiver

A terminal unit apparatus for a time division multiplexing access radio communications system formed of a base station and a number of terminal units remote from the base station, includes a 2-dimensional adaptive equalizer circuit for equalizing two quadrature-relationship baseband signals which are obtained from a received quadrature digital modulation signal during receiving operation of the terminal unit, and an internal signal source which generates a local oscillator signal for use in demodulating a received signal to obtain these baseband signals. A frequency correction quantity is derived from the average rate of variation in each symbol interval of the ratio of the two main tap coefficients of the 2-dimensional adaptive equalizer circuit, and used to correct the frequency of operation of the internal signal source during both receiving operation and also in transmitting operation, in which the internal signal source provides a carrier signal for modulation. Frequency correction can thereby be achieved that is independent of the effects of multi-path interference to the transmission path upon the received quadrature digital modulation signal.

Terminal unit apparatus for time division multiplexing access

A base station transmits a radio-frequency signal to a mobile station. The radio-frequency signal includes a frequency calibration signal. The mobile station includes a receiver receiving the radio-frequency signal. The receiver includes a referance oscillator generating a reference signal whose frequency is controlled in accordance with the frequency calibration signal. The receiver includes mixers and local oscillators. The mixers mix the radio-frequency signal with local oscillator signals from the local oscillator signals and convert the radio-frequency signal into a corresponding intermediate-frequency signal. The local oscillator signals are synchronized with the reference signal. The frequency of the intermediate-frequency signal is divided to derive a frequency-divided signal. The frequency of the reference signal is controlled in accordance with the frequency-divided signal.

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Yokohama, Japan

Yuuri Yamamoto