Communication system
First Claim
1. A communication system comprising:
- a transmitter having a signal input means, a modulator means for producing m (m≧
4) signal points in a signal space diagram expressed at least in a polar coordinate system (r, θ
) through modulation of a carrier wave using an input signal fed from the signal input means, and a transmitting means for transmitting a modulated signal modulated in said modulator means, in which said input signal contains a first data stream of n values and a second data stream, said m signal points are divided into n signal point groups, said n values of the first data stream are assigned to specify said n signal point groups respectively, and said second data stream is assigned to specify signal points in each signal point group; and
a receiver having an input means for reception of said modulated signal transmitted from the transmitter, a demodulating means for demodulating said modulated signal into a multi-level signal representing P signal points in a signal space diagram expressed at least in the polar coordinate system (r, θ
), and an output means for outputting a signal demodulated by said demodulating means, in which said P signal points are divided into signal point groups of n values, the first data stream of n values is demodulated so as to be assign to said n values of said signal point groups, and the second data stream of P/n values is demodulated so as to be assigned to P/n signal points of each point group for reconstruction of data of the first and second data streams.
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Accused Products
Abstract
At the transmitter side, carrier waves are modulated according to an input signal for producing relevant signal points in a signal space diagram. The input signal is divided into, two, first and second, data streams. The signal points are divided into signal point groups to which data of the first data stream are assigned. Also, data of the second data stream are assigned to the signal points of each signal point group. A difference in the transmission error rate between first and second data streams is developed by shifting the signal points to other positions in the space diagram expressed at least in the polar coordinate system. At the receiver side, the first and/or second data streams can be reconstructed from a received signal. In TV broadcast service, a TV signal is divided by a transmitter into, low and high, frequency band components which are designated as a first and a second data streams respectively. Upon receiving the TV signal, a receiver can reproduce only the low frequency band component or both the low and high frequency band components, depending on its capability. Furthermore, a communication system based on an OFDM system is utilized for data transmission of a plurality of subchannels, wherein the subchannels are differentiated by changing the length of a guard time slot or a carrier wave interval of a symbol transmission time slot, or changing the transmission electric power of the carrier.
92 Citations
8 Claims
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1. A communication system comprising:
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a transmitter having a signal input means, a modulator means for producing m (m≧
4) signal points in a signal space diagram expressed at least in a polar coordinate system (r, θ
) through modulation of a carrier wave using an input signal fed from the signal input means, and a transmitting means for transmitting a modulated signal modulated in said modulator means, in which said input signal contains a first data stream of n values and a second data stream, said m signal points are divided into n signal point groups, said n values of the first data stream are assigned to specify said n signal point groups respectively, and said second data stream is assigned to specify signal points in each signal point group; and
a receiver having an input means for reception of said modulated signal transmitted from the transmitter, a demodulating means for demodulating said modulated signal into a multi-level signal representing P signal points in a signal space diagram expressed at least in the polar coordinate system (r, θ
), and an output means for outputting a signal demodulated by said demodulating means, in which said P signal points are divided into signal point groups of n values, the first data stream of n values is demodulated so as to be assign to said n values of said signal point groups, and the second data stream of P/n values is demodulated so as to be assigned to P/n signal points of each point group for reconstruction of data of the first and second data streams. - View Dependent Claims (2, 3)
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4. A communication system based on an OFDM system in which a plurality of carriers being quadrate with each other are used for data transmission of a plurality of subchannels, characterized in that
a guard time slot containing no signal, disposed in front of a symbol transmission time slot on time base, is differentiated in each subchannel.
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6. A communication system based on an OFDM system in which a plurality of carriers being quadrate with each other are used for data transmission of a plurality of subchannels, characterized in that
a guard time slot containing no signal is disposed in front of a symbol transmission time slot on time base, and a carrier wave interval of said symbol transmission time slot is differentiated in each subchannel.
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8. A communication system based on an OFDM system in which a plurality of carriers being quadrate with each other are used for data transmission of a plurality of subchannels, characterized in that
transmission electric power of said carrier is differentiated in each subchannel.
Specification