Transmission apparatus and a reception apparatus in a multicarrier transmission system and a transmission method and a reception method using the multicarrier transmission system
Inter-carrier interference caused by frequency fluctuations, amplitude fluctuations, phase fluctuations, or the like is reduced without reducing a transmission efficiency. A receiving end has a canceling filter section that alleviates the inter-carrier interference caused by the frequency fluctuations, the amplitude fluctuations, the phase fluctuations, or the like through filtering processing. A transmitting end has a precoding section that facilitates determination of demodulation data in a vector demodulation section on the receiving end through precoding processing. Or, the receiving end has a trellis decoding section that decodes the demodulation data through trellis decoding processing.
1. A reception apparatus in a multicarrier transmission system which subjects a plurality of subcarriers, which are orthogonal with each other, to multicarrier modulation and transmits digital data, the reception apparatus comprising:
a multicarrier demodulation section for receiving a multicarrier modulation signal, demodulating the received multicarrier modulation signal, and outputting demodulation vectors obtained by the demodulation;
a canceling filter section for receiving the demodulation vectors, subjecting the demodulation vectors, which respectively correspond to the subcarriers neighboring in a frequency axis direction, to filtering processing which cancels inter-carrier interference, and outputting filtered demodulation vectors obtained by the filtering processing; and
a vector demodulation section for determining received data from the filtered demodulation vectors and outputting the data, wherein
the multicarrier demodulation section demodulates modulation vectors which modulate the subcarriers in a one-on-one relationship, and
the filtered demodulation vectors uniquely correspond to precoded modulation information obtained by subjecting transmitted data to precoding processing in a transmission apparatus, and a correspondence relationship thereof is determinable in the vector demodulation section.
2. The reception apparatus in the multicarrier transmission system according to claim 1 , wherein at a start of the filtering processing, the canceling filter section previously receives, from the transmission apparatus, and holds (L−1) demodulation vectors Y 2-L , . . . , Y 0 , which are needed when a first value Y 1 among values of the demodulation vectors is subjected to the filtering processing by using an equation for performing the filtering processing, as initial values prior to receiving the first value Y 1 among the values of the demodulation vectors vectors, the equation being:
Y
i
′
=
∑
l
=
0
L
-
1
P
l
Y
i
-
l
,
where
L is an integer that is greater than or equal to 2,
Y is a demodulation vector,
Y′ is a demodulation vector that has been subjected to filtering, and
P is a polynomial.
3. The reception apparatus in the multicarrier transmission system according to claim 1 , further comprising
a fluctuation amount estimation section for estimating a fluctuation amount of any one of frequency fluctuations, amplitude fluctuations, and phase fluctuations in the received multicarrier modulation signal, wherein
the fluctuation amount estimation section controls filter coefficients of the canceling filter section in accordance with the estimated fluctuation amount.
4. The reception apparatus in the multicarrier transmission system according to claim 1 , wherein the canceling filter section is constructed of an FIR (Finite Impulse Response) filter in which an impulse response, when a delay element is D, is represented as (1−D) (L−1) , where L is an integer that is greater than or equal to 2.
5. The reception apparatus in the multicarrier transmission system according to claim 1 , further comprising
a moving velocity measurement section for detecting a velocity at which the reception apparatus moves, wherein
filter coefficients of the canceling filter section are controlled in accordance with moving velocity information obtained by the moving velocity measurement section.
6. The reception apparatus in the multicarrier transmission system according to claim 5 , further comprising:
a velocity pulse generation section for a mobile unit, wherein
the moving velocity measurement section, based on a velocity pulse outputted by the velocity pulse generation section, obtains the moving velocity information of the reception apparatus.
7. The reception apparatus in the multicarrier transmission system according to claim 5 , wherein the moving velocity measurement section acquires positional information of the reception apparatus at predetermined time intervals and based on the positional information and the time intervals, obtains the moving velocity information of the reception apparatus.
8. A reception apparatus in a multicarrier transmission system which subjects a plurality of subcarriers, which are orthogonal with each other, to multicarrier modulation and transmits digital data, the reception apparatus comprising:
a multicarrier demodulation section for receiving a multicarrier modulation signal from a transmission apparatus, demodulating the multicarrier modulation signal, and outputting demodulation vectors obtained by the demodulation;
a canceling filter section for receiving the demodulation vectors, subjecting the demodulation vectors, which respectively correspond to the subcarriers neighboring in a frequency axis direction, to filtering processing which cancels inter-carrier interference, and outputting filtered demodulation vectors obtained by the filtering processing; and
a trellis decoding section for receiving the filtered demodulation vectors, subjecting the filtered demodulation vectors to decoding processing based on trellis transition using a state variable of the filtering processing, and outputting received data obtained by the decoding processing, wherein
the multicarrier demodulation section demodulates modulation vectors which modulate the subcarriers in a one-on-one relationship.
9. The reception apparatus in the multicarrier transmission system according to claim 8 , wherein at a start of the filtering processing, the canceling filter section previously receives, from the transmission apparatus, and holds (L−1) demodulation vectors Y 2-L , . . . , Y 0 , which are needed when a first value Y 1 among values of the demodulation vectors is subjected to the filtering processing by using an equation for performing the filtering processing, as initial values prior to receiving the first value Y 1 among the values of the demodulation vectors, the equation being:
Y
i
′
=
∑
l
=
0
L
-
1
P
l
Y
i
-
l
,
where
L is an integer that is greater than or equal to 2,
Y is a demodulation vector,
Y′ is a demodulation vector that has been subjected to filtering, and
P is a polynomial.
10. The reception apparatus in the multicarrier transmission system according to claim 8 , further comprising
a fluctuation amount estimation section for estimating a fluctuation amount of any one of frequency fluctuations, amplitude fluctuations, and phase fluctuations in the received multicarrier modulation signal, wherein
the fluctuation amount estimation section controls filter coefficients of the canceling filter section in accordance with the estimated fluctuation amount.
11. The reception apparatus in the multicarrier transmission system according to claim 8 , wherein the canceling filter section is constructed of an FIR (Finite Impulse Response) filter in which an impulse response, when a delay element is D, is represented as (1−D) (L−1) , where L is an integer that is greater than or equal to 2.
12. The reception apparatus in the multicarrier transmission system according to claim 8 , further comprising
a moving velocity measurement section for detecting a velocity at which the reception apparatus moves, wherein
filter coefficients of the canceling filter section are controlled based on moving velocity information obtained by the moving velocity measurement section.
13. The reception apparatus in the multicarrier transmission system according to claim 12 , further comprising:
a velocity pulse generation section for a mobile unit, wherein
the moving velocity measurement section, based on a velocity pulse outputted by the velocity pulse generation section, obtains the moving velocity information of the reception apparatus.
14. The reception apparatus in the multicarrier transmission system according to claim 12 , wherein the moving velocity measurement section acquires positional information of the reception apparatus at predetermined time intervals and based on the positional information and the time intervals, obtains the moving velocity information of the reception apparatus.
15. A reception method using a multicarrier transmission system which subjects a plurality of subcarriers, which are orthogonal with each other, to multicarrier modulation and transmits digital data, the reception method comprising:
a multicarrier demodulation step of receiving a multicarrier modulation signal, demodulating the received multicarrier modulation signal, and outputting demodulation vectors obtained by the demodulation;
a canceling filter step of receiving the demodulation vectors, subjecting the demodulation vectors, which respectively correspond to the subcarriers neighboring in a frequency axis direction, to filtering processing which cancels inter-carrier interference, and outputting filtered demodulation vectors obtained by the filtering processing; and
a vector demodulation step of determining received data from the filtered demodulation vectors and outputting the data, wherein
the multicarrier demodulation step demodulates the modulation vectors which modulate the subcarriers in a one-on-one relationship, and
the filtered demodulation vectors uniquely correspond to precoded modulation information obtained by subjecting transmitted data to precoding processing in a transmission apparatus, and a correspondence relationship thereof is determinable at the vector demodulation step.
16. A reception method using a multicarrier transmission system which subjects a plurality of subcarriers, which are orthogonal with each other, to multicarrier modulation and transmits digital data, the reception method comprising:
a multicarrier demodulation step of receiving a multicarrier modulation signal from a transmission apparatus, demodulating the multicarrier modulation signal, and outputting demodulation vectors obtained by the demodulation;
a canceling filter step of receiving the demodulation vectors, subjecting the demodulation vectors, which respectively correspond to the subcarriers neighboring in a frequency axis direction, to filtering processing which cancels inter-carrier interference, and outputting filtered demodulation vectors obtained by the filtering processing; and
a trellis decoding step of receiving the filtered demodulation vectors, subjecting the filtered demodulation vectors to decoding processing based on trellis transition using a state variable of the filtering processing, and outputting received data obtained by the decoding processing, wherein
the multicarrier demodulation step demodulates modulation vectors which modulate the subcarriers in a one-on-one relationship.