Signal generation method and signal generation device

1. An OFDM signal generation method of a transmission system, the transmission system having a first transmitter and a second transmitter, the OFDM signal generation method comprising:

encoding input data to coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;

modulating each of the coded blocks to a first modulated signal s 1 and a second modulated signal s 2 , data included in the first modulated signal s 1 being same as data included in the second modulated signal s 2 ;

applying precoding by a fixed matrix F to the first modulated signal s 1 and the second modulated signal s 2 to obtain a first pre-coded signal z 1 ′ and a second pre-coded signal z 2 ′, wherein

the matrix F is expressed as:

F

=

1

α

2

+

1

⁢

(

ⅇ

j0

α

×

ⅇ

jπ

α

×

ⅇ

j0

e

j0

)

where α represents 0;

inserting one or more pilots to each of the first pre-coded signal z 1 ′ and the second pre-coded signal z 2 ′ to obtain a first pilot-inserted signal z 1 ″ and a second pilot-inserted signal z 2 ″, respectively;

phase-changing, while regularly varying a scheme of phase change for each of a plurality of slots, at least one of the first pilot-inserted signal z 1 ″ and the second pilot-inserted signal z 2 ″ to obtain a first transmission signal z 1 and a second transmission signal z 2 , wherein at least one of the encoding, the modulating, the precoding, the inserting, and the phase-changing is performed by both the first transmitter and the second transmitter; and

converting, by the first transmitter, the first transmission signal z 1 to a first OFDM signal to be transmitted from a first antenna at a first period at a first frequency; and

converting, by the second transmitter, the second transmission signal z 2 to a second OFDM signal to be transmitted from a second antenna at the first period at the first frequency.

2. An OFDM signals generation system comprising:

a first OFDM signal generator; and

a second OFDM signal generator,

wherein both the first OFDM signal generator and the second OFDM signal generator are operable to:

encode input data to coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;

modulate each of the coded blocks to a first modulated signal s 1 and a second modulated signal s 2 , data included in the first modulated signal s 1 being same as data included in the second modulated signal s 2 ;

apply precoding by a fixed matrix F to the first modulated signal s 1 and the second modulated signal s 2 to obtain a first pre-coded signal z 1 ′ and a second pre-coded signal z 2 ′, wherein

the matrix F is expressed as:

F

=

1

α

2

+

1

⁢

(

ⅇ

j0

α

×

ⅇ

jπ

α

×

ⅇ

j0

e

j0

)

where α represents 0;

insert one or more pilots to each of the first pre-coded signal z 1 ′ and the second pre-coded signal z 2 ′ to obtain a first pilot-inserted signal z 1 ″ and a second pilot-inserted signal z 2 ″, respectively; and

phase-change, while regularly varying a scheme of phase change for each of a plurality of slots, at least one of the first pilot-inserted signal z 1 ″ and the second pilot-inserted signal z 2 ″ to obtain a first transmission signal z 1 and a second transmission signal z 2 ; and

the first OFDM signal generator is operable to:

convert the first transmission signal z 1 to a first OFDM signal to be transmitted from a first antenna at a first period at a first frequency; and

the second OFDM signal generator is operable to:

convert the second transmission signal z 2 to a second OFDM signal to be transmitted from a second antenna at the first period at the first frequency.

3. A reception data generation method of a reception apparatus, the method comprising:

acquiring a reception signal obtained by converting a first OFDM signal transmitted from a first antenna of a first transmitter at a first period at a first frequency and a second OFDM signal transmitted from a second antenna of a second transmitter at the first period at the first frequency, the first OFDM signal and the second OFDM signal having been generated through a predetermined generation process; and

demodulating the reception signal to reception data, through a demodulation process corresponding to the predetermined generation process, wherein

at least one of the acquiring and the demodulating is performed by the reception apparatus, and

the predetermined generation process is a process of:

encoding input data to coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;

modulating each of the coded blocks to a first modulated signal s 1 and a second modulated signal s 2 , data included in the first modulated signal s 1 being same as data included in the second modulated signal s 2 ;

applying precoding by a fixed matrix F to the first modulated signal s 1 and the second modulated signal s 2 to obtain a first pre-coded signal z 1 ′ and a second pre-coded signal z 2 ′, wherein

the matrix F is expressed as:

F

=

1

α

2

+

1

⁢

(

ⅇ

j0

α

×

ⅇ

jπ

α

×

ⅇ

j0

e

j0

)

where α represents 0;

inserting one or more pilots to each of the first pre-coded signal z 1 ′ and the second pre-coded signal z 2 ′ to obtain a first pilot-inserted signal z 1 ″ and a second pilot-inserted signal z 2 ″, respectively;

phase-changing, while regularly varying a scheme of phase change for each of a plurality of slots, at least one of the first pilot-inserted signal z 1 ″ and the second pilot-inserted signal z 2 ″ to obtain a first transmission signal z 1 and a second transmission signal z 2 ;

converting, by the first transmitter, the first transmission signal z 1 to the first OFDM signal; and

converting, by the second transmitter, the second transmission signal z 2 to the second OFDM signal.

4. A reception data generation apparatus comprising:

a memory; and

control circuitry,

wherein the control circuitry is operable to perform the steps of:

acquiring a reception signal obtained by converting a first OFDM signal transmitted from a first antenna of a first transmitter at a first period at a first frequency and a second OFDM signal transmitted from a second antenna of a second transmitter at the first period at the first frequency, the first OFDM signal and the second OFDM signal having been generated through a predetermined generation process; and

demodulating the reception signal to reception data, through a demodulation process corresponding to the predetermined generation process, wherein

at least one of the acquiring and the demodulating is performed by the control circuitry, and

the predetermined generation process is a process of:

encoding input data to coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;

modulating each of the coded blocks to a first modulated signal s 1 and a second modulated signal s 2 , data included in the first modulated signal s 1 being same as data included in the second modulated signal s 2 ;

applying precoding by a fixed matrix F to the first modulated signal s 1 and the second modulated signal s 2 to obtain a first pre-coded signal z 1 ′ and a second pre-coded signal z 2 ′, wherein

the matrix F is expressed as:

F

=

1

α

2

+

1

⁢

(

ⅇ

j0

α

×

ⅇ

jπ

α

×

ⅇ

j0

e

j0

)

where α represents 0;

inserting one or more pilots to each of the first pre-coded signal z 1 ′ and the second pre-coded signal z 2 ′ to obtain a first pilot-inserted signal z 1 ″ and a second pilot-inserted signal z 2 ″, respectively; and

phase-changing, while regularly varying a scheme of phase change for each of a plurality of slots, at least one of the first pilot-inserted signal z 1 ″ and the second pilot-inserted signal z 2 ″ to obtain a first transmission signal z 1 and a second transmission signal z 2 ;

converting, by the first transmitter, the first transmission signal z 1 to the first OFDM signal; and

converting, by the second transmitter, the second transmission signal z 2 to the second OFDM signal.