# US 9,882,618 B2 · Signal generation method and signal generation device

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- Number: US 9,882,618 B2
- Document ID: US9882618B2
- Status: Granted
- Kind: B2
- Application number: 15/240,187
- Filed: 2016-08-18
- Published: 2016-12-29
- Granted: 2018-01-30
- Earliest claimed: 2010-12-10
- Assignees: Sun Patent Trust
- Applicants: Sun Patent Trust
- Inventors: Yutaka Murakami; Tomohiro Kimura; Mikihiro Ouchi
- Web page: https://patentgrep.com/patent/US9882618B2

## CPC

- H04B 7/0413: MIMO systems
- G06F 11/10: Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's
- H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B 7/0482: {Adaptive codebooks}
- H04B 7/0682: {using phase diversity (e.g. phase sweeping)}
- H04B 7/0697: {using spatial multiplexing}
- H04L 1/0058: {Block-coded modulation}
- H04L 5/005: {of common pilots, i.e. pilots destined for multiple users or terminals}
- H04L 25/0224: {using sounding signals}
- H04L 25/03898: {codebook-based design (selection of codebook or precoding matrix for MIMO diversity systems H04B7/0456)}
- H04L 25/067: {providing soft decisions, i.e. decisions together with an estimate of reliability (H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178)}
- H04L 27/2627: {Modulators}
- H04W 72/044: based on the type of the allocated resource
- H04B 7/0669: {using different channel coding between antennas (space-time coding H04L1/0618)}
- H04B: TRANSMISSION
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A transmission method simultaneously transmitting a first modulated signal and a second modulated signal at a common frequency performs precoding on both signals using a fixed precoding matrix and regularly changes the phase of at least one of the signals, thereby improving received data signal quality for a reception device.

## Claims

### Claim 1

An OFDM signal generation method of a transmission system, the transmission system having a first transmitter and a second transmitter, the OFDM signal generating method comprising:
modulating, by the first transmitter, each of a plurality of coded blocks to a first modulated signal s1, the coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;
modulating, by the second transmitter, each of the coded blocks to a second modulated signal s2, data included in the first modulated signal s1 being same as data included in the second modulated signal s2;
inserting, by the first transmitter, one or more pilots to the first modulated signal s1 to obtain a first pilot-inserted signal s1′;
inserting, by the second transmitter, the one or more pilots to the second modulated signal s2 to obtain a second pilot-inserted signal s2′;
phase-changing, by the first transmitter, while regularly varying a first scheme of phase change for each of a plurality of slots, the first pilot-inserted signal s1′ to obtain a first transmission signal z1; and
phase-changing, by the second transmitter, while regularly varying a second scheme of phase change for each of the plurality of slots, the second pilot-inserted signal s2′ to obtain a second transmission signal z2; and
converting, by the first transmitter, the first transmission signal z1 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 z2 to a second OFDM signal to be transmitted from a second antenna at the first period at the first frequency.

### Claim 2

An OFDM signal generation system comprising:
a first OFDM signal generator; and
a second OFDM signal generator,
wherein the first OFDM signal generator, in operation,
modulates each of a plurality of coded blocks to a first modulated signal s1, the coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;
inserts one or more pilots to the first modulated signal s1 to obtain a first pilot-inserted signal s1′;
phase-changes, while regularly varying a first scheme of phase change for each of a plurality of slots, the first pilot-inserted signal s1′ to obtain a first transmission signal z1; and
converts the first transmission signal z1 to a first OFDM signal to be transmitted from a first antenna at a first period at a first frequency; and
wherein the second OFDM signal generator, in operation,
modulates each of the coded blocks to a second modulated signal s2, data included in the first modulated signal s1 being same as data included in the second modulated signal s2;
inserts the one or more pilots to the second modulated signal s2 to obtain a second pilot-inserted signal s2′;
phase-changes, while regularly varying a second scheme of phase change for each of the plurality of slots, the second pilot-inserted signal s2′ to obtain a second transmission signal z2; and
converts the second transmission signal z2 to a second OFDM signal to be transmitted from a second antenna at the first period at the first frequency.

### Claim 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:
modulating, by the first transmitter, each of a plurality of coded blocks to a first modulated signal s1, the coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;
modulating, by the second transmitter, each of the coded blocks to a second modulated signal s2, data included in the first modulated signal s1 being same as data included in the second modulated signal s2;
inserting, by the first transmitter, one or more pilots to the first modulated signal s1 to obtain a first pilot-inserted signal s1′;
inserting, by the second transmitter, the one or more pilots to the second modulated signal s2 to obtain a second pilot-inserted signal s2′;
phase-changing, by the first transmitter, while regularly varying a first scheme of phase change for each of a plurality of slots, the first pilot-inserted signal s1′ to obtain a first transmission signal z1; and
phase-changing, by the second transmitter, while regularly varying a second scheme of phase change for each of the plurality of slots, the second pilot-inserted signal s2′ to obtain a second transmission signal z2; and
converting, by the first transmitter, the first transmission signal z1 to the first OFDM signal, which is transmitted from the first antenna at the first period at the first frequency; and
converting, by the second transmitter, the second transmission signal z2 to the second OFDM signal, which is transmitted from the second antenna at the first period at the first frequency.

### Claim 4

A reception data generation apparatus comprising:
a memory; and
control circuitry,
wherein the control circuitry, in operation, performs 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:
modulating, by the first transmitter, each of a plurality of coded blocks to a first modulated signal s1, the coded blocks each made up of a plurality of bits by using a predetermined error correction block coding scheme;
modulating, by the second transmitter, each of the coded blocks to a second modulated signal s2, data included in the first modulated signal sl being same as data included in the second modulated signal s2;
inserting, by the first transmitter, one or more pilots to the first modulated signal s1 to obtain a first pilot-inserted signal s1′;
inserting, by the second transmitter, the one or more pilots to the second modulated signal s2 to obtain a second pilot-inserted signal s2′;
phase-changing, by the first transmitter, while regularly varying a first scheme of phase change for each of a plurality of slots, the first pilot-inserted signal sl′ to obtain a first transmission signal z1; and
phase-changing, by the second transmitter, while regularly varying a second scheme of phase change for each of the plurality of slots, the second pilot-inserted signal s2′ to obtain a second transmission signal z2; and
converting, by the first transmitter, the first transmission signal z1 to the first OFDM signal, which is transmitted from the first antenna at the first period at the first frequency; and
converting, by the second transmitter, the second transmission signal z2 to the second OFDM signal, which is transmitted from the second antenna at the first period at the first frequency.