Modulating apparatus, mobile communication system, modulating method, and communication method
View Patent ↗An encoder encodes sound data and the like to generate a binary signal. A mapper converts the binary signal into a four-level symbol and outputs the four-level symbol. A base band filter includes a root raised cosine filter and a sinc filter. The base band filter blocks a predetermined frequency component of a symbol to shape the symbol into a waveform signal and outputs the waveform signal shaped. An FM modulator transmits a signal subjected to FM modulation according to a magnitude of an amplitude of a waveform signal to a receiving unit. When a symbol of ±3 is outputted from the mapper, a frequency shift of a signal transmitted from the FM modulator has a predetermined value in a range of ±0.822[kHz] to ±0.952[kHz]. This makes it possible to provide a modulating apparatus, a mobile communication system, a modulating method, and a communication method that use a modulating method that can conform to the FCC rule to be enforced in 2005 without using a linear power amplifier.
1. A mobile communication system comprising:
a transmitter that performs transmission of data at a transmission rate of 2400×(n+1) (n: natural number) [bps]; and
a receiver that receives data transmitted from the transmitter,
the transmitter includes:
encoding means for encoding predetermined data to generate a binary signal;
symbol converting means for sequentially converting the binary signal generated by the encoding means into a 2 (n+1) -ary symbol, which includes (2 (n+1) +1−2 k) (1≦k≦2 (n+1) ) values, (n+1) bits at a time and outputting the symbol;
a first base band filter that blocks an unnecessary frequency component of the symbol inputted from the symbol converting means and outputs a waveform signal; and
frequency shifting and modulating (FM) means for transmitting a signal, which is obtained by shifting to modulate a frequency according to a magnitude of an amplitude of the waveform signal inputted from the first base band filter, to the receiver,
the receiver includes:
demodulating means for demodulating the signal transmitted from the transmitter and received and outputting a 2 (n+1) -ary signal;
a second base band filter that blocks an unnecessary frequency component of the 2 (n+1) -ary signal outputted from the demodulating means and outputs the 2 (n+1) -ary signal;
binary signal converting means for sequentially converting the 2 (n+1) -ary signal inputted from the second base band filter into the binary signal of (n+1) bits and outputting the binary signal; and
decoding means for decoding the binary signal inputted from the binary signal converting means and outputting the predetermined data, and
wherein when a symbol of +(2 (n+1) −1) and a symbol of −(2 (n+1) −1) are alternately and repeatedly outputted from the symbol converting means, a frequency shift of the signal outputted from the frequency shifting and modulating means is set within a range of ±0.822 [kHz] to ±0.952 [kHz], and
wherein the transmission path from the encoding means included in the transmitter to the decoding means included in the receiver forms a Nyquist transmission path.
2. A communication method in a mobile communication system including a transmitter that performs transmission of data at a transmission rate of 2400×(n+1) (n: natural number) [bps] and a receiver that receives data transmitted from the transmitter, characterized by comprising:
an encoding step of encoding predetermined data to generate a binary signal;
a symbol converting step of sequentially converting the binary signal generated by the encoding step into a 2 (n+1) -ary symbol, which includes (2 (n+1) +1−2 k) (1≦k≦2 (n+1) ) values, (n+1) bits at a time and outputting the symbol;
a first base band filtering step of blocking an unnecessary frequency component of the symbol inputted from the symbol converting step and outputting a waveform signal;
a frequency shifting and modulating step of transmitting a signal, which is obtained by shifting to modulate a frequency according to a magnitude of an amplitude of the waveform signal inputted from the first base band filtering step, to the receiver;
a demodulating step of demodulating the signal transmitted from the transmitter and received and outputting a 2 (n+1) -ary signal;
a second base band filtering step of blocking an unnecessary frequency component of the 2 (n+1) -ary signal outputted from the demodulating step and outputting the 2 (n+1) -ary signal;
a binary signal converting step of sequentially converting the 2 (n+1) -ary signal inputted from the second base band filtering step into the binary signal of (n+1) bits and outputting the binary signal; and
a decoding step of decoding the binary signal inputted from the binary signal converting step and outputting the predetermined data,
wherein when a symbol of +(2 (n+1) −1) and a symbol of −(2 (n+1) −1) are alternately and repeatedly outputted from the symbol converting step, a frequency shift of the signal outputted from the frequency shifting and modulating step is set to take a value within a range of ±0.822 [kHz] to ±0.952 [kHz] and
wherein the transmission path from the encoding step to the decoding step forms a Nyquist transmission path.