Mitsubishi Electric Corporation

Akinori Ohashi

Hiroshi Nishimoto

Masatsugu Higashinaka

Shusaku Umeda

Yasunori Noda

A communication device includes a signal determiner determining whether there is a reception signal, and a period estimator estimating an interruption period of interruption of a signal transmitted from a device as a source of the reception signal, using a determination result from the signal determiner. The period estimator includes a differential operator calculating a differential value of the determination result, a masking operator calculating a provisional period of the interruption period using the differential value, controlling use of the differential value and provisional period based on internal state, and outputting the provisional period to be used, a period calculator calculating the interruption period using the provisional period, a signal existing section calculator calculating a signal existing section using the provisional period, a periodic timing estimator estimating periodic timing using the provisional period and signal existing section, and a state determiner determining the internal state using the interruption period.

Communication device, method for predicting interruption, control circuit, and program recording medium

A communication system using hierarchical modulation and capable of flexibly adjusting line quality includes a transmission apparatus that hierarchically modulates and transmits signal sequences, a reception apparatus that hierarchically demodulates a received signal, and a hierarchization-parameter setting unit that sets hierarchization parameters. The transmission apparatus includes a hierarchical modulation unit that superimposes signals from layers while maintaining gray codes. The reception apparatus includes a hierarchical demodulation unit that demodulates and separates hierarchically modulated signals and detects signals from layers. The hierarchization-parameter setting unit sets a hierarchization ratio which is a signal power ratio used for superimposing a higher layer and a lower layer, a mapping pattern capable of selecting two patterns, and a mapping pattern mixing ratio indicating a ratio with which two mapping patterns are mixed.

Communication system, transmission apparatus, reception apparatus, and digital transmission method

A bit-likelihood calculating apparatus includes an initial-bit-likelihood calculating unit obtaining an inter-transmission-signal-point distance corresponding to N, a region number indicating a determination region of a transmission signal point nearest from data, and inter-nearest-point distance from a transmission signal point of initial bit=0 nearest to the data and a transmission signal point of initial bit=1 nearest to the data, and calculating likelihood of initial bit of the data serving as initial term of a recurrence formula for recursively calculating bit likelihood, an i-th-bit-likelihood calculating unit calculating, when N is 2 or larger, difference between inter-nearest-point distance with respect to (i&#x2212;1)th bit and inter-nearest-point distance with respect to i-th bit and calculating likelihood of i-th bit of the data from likelihood of (i&#x2212;1)th bit and the difference using the recurrence formula, and a processing-step control unit controlling calculation processing for bit likelihood based on N.

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Tokyo, Japan

Akinori Ohashi