OFDM communication method and OFDM communication device

• US 7,463,577 B2
• Filed: 04/09/2003
• Issued: 12/09/2008
• Est. Priority Date: 04/09/2002
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation, Panasonic Mobile Communications Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Sudo, Hiroaki, Sugiyama, Takatoshi, Asai, Yusuke
• Primary Examiner(s): Pham; Brenda
• Assistant Examiner(s): Davenport; Mon Cheri S
• Application Number:
  US10/488,610
• Publication Number:
  US 20040233838A1
• Time in Patent Office: 2,071 Days
• Field of Search: 370/203, 370/208, 370/210, 370/295, 370/319, 370/334, 370/339, 370/343, 370/349
• US Class Current: 370/208
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 25/0232 by interpolation between sounding signals
• CPC Class Codes: H04L 25/0244 with inversion
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0028 Variable division signaling therefor H04L5/0092
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0082 at predetermined intervals
• CPC Class Codes: H04L 5/0085 when channel conditions change

Abstract

When OFDM signals are transmitted from a plurality of antennas, a pilot carrier is transmitted from one antenna among the plurality of antennas, and a null signal is transmitted from an antenna other than that antenna by a subcarrier of the frequency band that transmits the pilot carrier.

Claims

1. An orthogonal frequency division multiplexing (OFDM) communication apparatus comprising:

a plurality of antennas;

an OFDM signal forming section that forms a plurality of OFDM signals transmitted from the plurality of antennas by executing OFDM processing of a plurality of transmit data; and

a selection section that selects whether to insert a known signal or a null signal in a predetermined subcarrier of each OFDM signal in a cycle of predetermined time, wherein;

during a first cycle of time, the selection section inserts a known signal in a subcarrier of a first OFDM signal for transmission by a first antenna and inserts a null signal in a corresponding subcarrier of a second OFDM signal for transmission by a second antenna, such that the corresponding subcarriers within the first cycle of time have the same frequency band,

during a second cycle of time that does not overlap the first cycle of time, the selection section inserts a null signal in a subcarrier of a third OFDM signal for transmission by the first antenna and inserts a known signal in a corresponding subcarrier of a fourth OFDM signal for transmission by the second antenna, such that the corresponding subcarriers within the second cycle of time have the same frequency band,

the subcarrier conveying the known signal within the first OFDM signal has the same frequency band as the subcarrier conveying the null signal in the third OFDM signal, and

the subcarrier conveying the null signal in the second OFDM signal has the same frequency band as the subcarrier conveying the known signal in the fourth OFDM signal.

2. An orthogonal frequency division multiplexing (OFDM) communication method comprising the steps of:

forming a plurality of OFDM signals transmitted from a plurality of antennas by executing OFDM processing of each of a plurality of transmit data;

inserting, during a first cycle of time, a known signal in a subcarrier of a first OFDM signal for transmission by a first antenna and inserting a null signal in a corresponding subcarrier of a second OFDM signal for transmission by a second antenna, such that the corresponding subcarriers within the first cycle of time have the same frequency band; and

inserting, during a second cycle of time that does not overlap the first cycle of time, a null signal in a subcarrier of a third OFDM signal for transmission by the first antenna and inserting a known signal in a corresponding subcarrier of a fourth OFDM signal for transmission by the second antenna, such that the corresponding subcarriers within the second cycle of time have the same frequency band, wherein;

the subcarrier conveying the known signal within the first OFDM signal has the same frequency band as the subcarrier conveying the null signal in the third OFDM signal, and

the subcarrier conveying the null signal in the second OFDM signal has the same frequency band as the subcarrier conveying the known signal in the fourth OFDM signal.