Radio transmitting apparatus and radio transmission method

• US 7,324,481 B2
• Filed: 08/04/2004
• Issued: 01/29/2008
• Est. Priority Date: 08/07/2003
• Status: Active Grant

• Current Assignee: Redwood Technologies, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Murakami, Yutaka, Kobayashi, Kiyotaka, Orihashi, Masayuki
• Primary Examiner(s): Nguyen, Duc M.
• Assistant Examiner(s): Elcenko, Eric J
• Application Number:
  US10/566,682
• Publication Number:
  US 20060189279A1
• Time in Patent Office: 1,273 Days
• Field of Search: 370/334, 370/339, 455/101, 455/103, 455/522
• US Class Current: 370/334
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

A radio transmitting apparatus that has a plurality of antennas and changes the number of modulated signals transmitted simultaneously according to the propagation environment and so forth. A transmission power changing section 12 of a radio transmitting apparatus of the present invention adjusts the pilot symbol signal level so as to match the data symbol composite signal level according to the number of transmit modulated signals set by a modulated signal number setting section 11. By this means, the operating range of received pilot symbols and the operating range of received data symbols become approximately the same on the receiving side, enabling pilot symbol quantization error to be reduced. As a result, the precision of radio wave propagation environment estimation, time synchronization, and frequency offset estimation using pilot symbols improves, and consequently data reception quality improves.

Claims

1. A radio transmission method for transmitting data symbols using at least one antenna, the method comprising:

transmitting a first preamble including a signal point amplitude greater than a maximum signal point amplitude among signal point amplitudes of the data symbols, using at least one antenna; and

transmitting a second preamble including a signal point amplitude smaller than the signal point amplitude included in the first preamble, using a greater number of antennas than the at least one antenna transmitting the first preamble.

3. The radio transmission method of claim 1, further comprising:

transmitting the data symbols after transmitting the first preamble and the second preamble, using at least one antenna.

5. The radio transmission method of claim 1, wherein the second preamble comprises an AGC symbol.

2. A radio transmission method for transmitting data symbols, a first preamble and a second preamble using a first antenna and a second antenna, the method comprising:

transmitting the first preamble including a signal point amplitude greater than a maximum signal point amplitude among signal point amplitudes of the data symbols, using at least one of the first antenna and the second antenna; and

transmitting the second preamble including a signal point amplitude smaller than the signal point amplitude included in the first preamble, using the first antenna and the second antenna.

4. The radio transmission method of claim 2, further comprising:

transmitting the data symbols after transmitting the first preamble and the second preamble, using at least one of the first antenna and the second antenna.

6. The radio transmission method of claim 2, wherein the second preamble comprises an AGC symbol.