Data unit detection including antenna diversity

• US 20050096001A1
• Filed: 12/07/2004
• Published: 05/05/2005
• Est. Priority Date: 06/29/1999
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kandala, Srinivas
• Granted Patent: US 7,450,922 B2
• Time in Patent Office: Days
• US Class Current: 455/269
• CPC Class Codes: H04B 7/0808 comparing all antennas before reception

Abstract

A system adjusts a receiving device in response to sensing symbols. An automatic gain control is adjusted in response receiving a first symbol of a data unit from a first antenna. After adjusting the automatic gain control at least a second and a third symbol of the data unit are received, and in response thereto (1) a first energy of at least one of the second and third symbols is calculated, (2) a first frequency offset of at least one of the second and third symbols is calculated, and (3) a first temporal offset of at least one of the second and third symbols is calculated. The automatic gain control in response receiving a fourth symbol of the data unit from a second antenna is received. After adjusting the automatic gain control at least a fifth and a sixth symbol of the data unit is calculated, and in response thereto (1) a second energy of at least one of the fifth and sixth symbols is calculated, (2) a second frequency offset of at least one of the fifth and sixth symbols is calculated, and (3) a second temporal offset of at least one of the fifth and sixth symbols is calculated. At least one of the first and second antenna is selected based upon a comparison between the first and second energy. In this manner, antenna diversity selection may be performed within a limited duration of available symbols.

Claims

1. A method of adjusting a receiving device in response to sensing symbols comprising:

(a) adjusting an automatic gain control in response receiving a first symbol of a data unit from a first antenna;

(b) after adjusting said automatic gain control receiving at least a second and a third symbol of said data unit and in response thereto

(1) calculating a first energy of at least one of said second and third symbol, (2) calculating a first frequency offset of at least one of said second and third symbol, and (3) calculating a first temporal offset of at least one of said second and third symbol;

(c) adjusting said automatic gain control in response receiving a fourth symbol of said data unit from a second antenna;

(d) after adjusting said automatic gain control receiving at least a fifth and a sixth symbol of said data unit and in response thereto

(1) calculating a second energy of at least one of said fifth and sixth symbol, (2) calculating a second frequency offset of at least one of said fifth and sixth symbol, and (3) calculating a second temporal offset of at least one of said fifth and sixth symbol; and

(e) selecting at least one of said first and second antenna based upon a comparison between said first and second energy.

2. The method of claim 1 wherein said automatic gain control is a single automatic gain control circuit.

3. The method of claim 1 wherein said first, second, third, fourth, and fifth symbols are in a non-sequential order.

4. The method of claim 1 wherein said automatic gain control adjusts the amplitude variation of the received symbols at the input to an analog-to-digital converter.

5. The method of claim 1 wherein said first frequency offset and said second frequency offsets are coarse offset frequency determinations.

6. The method of claim 1 wherein said first temporal offset and said second temporal offset are timing synchronization.

7. The method of claim 1 wherein said comparison between said first and second energy is a magnitude determination.

8. The method of claim 1 further comprising sensing an initial symbol from said first antenna prior to said first symbol.

9. The method of claim 8 further comprising sensing an intermediate symbol from said second antenna prior to sensing said fourth symbol and after sensing said third symbol.

10. The method of claim 9 further comprising switching from said first antenna to said second antenna prior to receiving said fourth symbol and after receiving said first symbol.

11. The method of claim 10 wherein said switching occurs during one symbol duration.

12. The method of claim 10 wherein said first symbol, said second symbol, said third symbol, said fourth symbol, said fifth symbol, said sixth symbol, said switching, said initial symbol, and said intermediate symbol occurs within a time duration of nine symbols.

13. The method of claim 12 further comprising switching from said second antenna to said first antenna after receiving said sixth symbol and no later than a tenth symbol of said data unit.

14. The method of claim 8 wherein said sixth symbol is received no later than a tenth symbol of said data unit.

15. The method of claim 9 wherein said sixth symbol is received no later than a tenth symbol of said data unit.

16. The method of claim 10 wherein said sixth symbol is received no later than a tenth symbol of said data unit.

17. The method of claim 12 wherein said sixth symbol is received no later than a tenth symbol of said data unit.