WE CLAIM:
1. A transmitter compatible with a multicarrier block
transmission scheme, the transmitter comprising:
a fixed sequence generation unit to generate a fixed sequence;
a data sequence generation unit to convert data symbols into a time domain signal to generate a data signal;
a multiplexing unit to divide the fixed sequence into two divisions, place one of the two divisions at a head and another one of the two divisions at a tail of a block, and place a data sequence that is an output signal from the data sequence generation unit between the two divisions to generate a block signal; and
an interpolation unit to perform interpolation processing on the block signal.
2. The transmitter according to claim 1, wherein
the fixed sequence generation unit generates a nonzero fixed sequence.
3. The transmitter according to claim 1, wherein
the fixed sequence generation unit is a first fixed sequence generation unit to generate a zero sequence, and
the transmitter further including:
a second fixed sequence generation unit to generate a nonzero fixed sequence and perform interpolation processing on the generated nonzero fixed sequence to generate an interpolated fixed sequence; and
a combining unit to combine the block signal subjected to the interpolation processing in the interpolation unit and the interpolated fixed sequence.

4. The transmitter according to any one of claims 1 to 3,
wherein
the data sequence generation unit includes:
a data generation unit to generate the data symbols;
a conversion unit to convert the data symbols into the data signal; and
an adjustment unit to generate the data sequence for adjusting a length of the data signal to be equal to a difference between a length of the block signal and a length of the fixed sequence.
5. The transmitter according to any one of claims 1 to 3,
wherein
the data sequence generation unit includes:
a data generation unit to generate the data symbols;
and
a conversion unit to convert the data symbols into the
data signal having the same length as a difference between
a length of the block signal and a length of the fixed
sequence to generate the data sequence.
6. The transmitter according to any one of claims 1 to 5,
wherein
the interpolation unit includes:
a frequency domain conversion unit to convert the block signal into a frequency domain signal;
a zero insertion unit to insert zeros into the frequency domain signal; and
a time domain conversion unit to convert the frequency domain signal including the zeros inserted by the zero insertion unit into a time domain signal.
7. The transmitter according to any one of claims 1 to 6,

wherein
the fixed sequence generation unit generates the fixed sequence having the length determined based on a state of a transmission path to a receiver that receives the block signal.
8. The transmitter according to claim 7, wherein
the state of the transmission path is a maximum value of a delay time that is added on the transmission path to a signal transmitted by the transmitter.
9. The transmitter according to any one of claims 1 to 8,
wherein
the two divisions of the fixed sequences which are obtained by dividing the fixed sequence into two divisions by the multiplexing unit have lengths determined based on an amount of suppression of out-of-band power of a signal transmitted by the transmitter.
10. A receiver that receives a signal transmitted from the
transmitter according to any one of claims 1 to 9, the
receiver comprising:
a signal waveform restoration unit to execute, on a reception signal, reverse processing of the interpolation processing performed by the interpolation unit, and execute frequency domain equalization on the obtained signal;
a signal extraction unit to extract the data sequence from the signal obtained using the frequency domain equalization; and
a demodulation unit to demodulate the data sequence extracted by the signal extraction unit.
11. A communication system comprising:

a base station including the transmitter according to any one of claims 1 to 9; and
a terminal including the receiver according to claim 10.
12. A transmission method that is executed by a transmitter compatible with a multicarrier block transmission scheme, the method comprising:
a fixed sequence generation step of generating a fixed sequence;
a data signal generation step of converting data symbols into a time domain signal to generate a data signal;
a data sequence generation step of generating a data sequence based on the data signal;
a multiplexing step of dividing the fixed sequence into two divisions, placing one of the two divisions at a head and another one of the two divisions at a tail of a block, and placing the data sequence between the two divisions to generate a block signal; and
an interpolation step of performing interpolation processing on the block signal.