Packet Detection Apparatus and Method, Wireless Communication Apparatus and Method, and Computer Program

• US 20090304128A1
• Filed: 08/04/2009
• Published: 12/10/2009
• Est. Priority Date: 08/06/2008
• Status: Abandoned Application

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Ito, Osamu, IZUMI, Seiichi
• Application Number:
  US12/535,405
• Publication Number:
  US 20090304128A1
• Time in Patent Office: Days
• US Class Current: 375/343
• CPC Class Codes: H04L 27/2655 Synchronisation arrangements
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation

Abstract

A packet detection apparatus detects a packet from a received signal by using a preamble containing an established, repeating training sequence. A first autocorrelation calculator computes a first autocorrelation of the received signal over a first interval. A first determining unit determines packet discovery by comparing the first autocorrelation to a first autocorrelation threshold value. A second autocorrelation calculator computes a second autocorrelation of the received signal over a second interval equivalent to the interval length for packet discovery announcement. A second determining unit determines packet discovery announcement by comparing the second autocorrelation to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

Claims

1. A packet detection apparatus that detects a packet from a received signal by using a preamble made up of an established, repeating training sequence added to the beginning of the packet, the packet detection apparatus comprising:

a first autocorrelation calculator configured to solve for a first autocorrelation of the received signal over a first interval;

a first determining unit configured to make a packet discovery determination on the basis of the result of comparing the first autocorrelation computed by the first autocorrelation calculator to a first autocorrelation threshold value;

a second autocorrelation calculator configured to solve for a second autocorrelation of the received signal over a second interval equivalent to the interval length for packet discovery announcement; and

a second determining unit configured to make a packet discovery announcement determination on the basis of the result of comparing the second autocorrelation computed by the second autocorrelation calculator to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

2. The packet detection apparatus according to claim 1, wherein the first interval is equivalent to the preamble interval length, and the second interval is shorter than the first interval.

3. The packet detection apparatus according to claim 1, wherein the first and the second autocorrelation calculators respectively compute moving averages of the complex conjugate multiplication results for the received signal and a delay signal received earlier by one repeating period of the training sequence in the first and second intervals.

4. The packet detection apparatus according to claim 1, wherein the first determining unit additionally makes a packet discovery announcement if the second determining unit has not yet made a packet discovery announcement determination at the time of the first determining unit determining packet discovery.

5. A packet detection apparatus that detects a packet from a received signal by using a preamble made up of an established, repeating training sequence added to the beginning of the packet, the packet detection apparatus comprising:

an autocorrelation calculator configured to solve for the autocorrelation of the received signal for each repeating period of the established training sequence;

a normalizer configured to normalize the autocorrelation computed by the autocorrelation calculator to the average received signal power in a given interval;

a plurality of serially-connected delay units each configured to apply delay equal to one repeating period of the established training sequence, wherein the number of delay units corresponds to the number of times the established training sequence is repeated;

a first summing unit configured to calculate the sum of the normalized autocorrelations respectively output from the normalizer and all of the serially-connected delay units;

a first determining unit configured to make a packet discovery determination on the basis of the result of comparing the first normalized autocorrelation sum output by the first summing unit to a first autocorrelation threshold value;

a second summing unit configured to calculate the sum of the normalized autocorrelations respectively output from the normalizer and a predetermined number of serially-connected delay units starting from the first; and

a second determining unit configured to make a packet discovery announcement determination on the basis of the result of comparing the second normalized autocorrelation sum output by the second summing unit to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

6. The packet detection apparatus according to claim 5, wherein the total delay time calculated by the second summing unit and found in the output of the last delay unit is equivalent to the interval length for packet discovery announcement.

7. The packet detection apparatus according to claim 5, wherein the first determining unit additionally makes a packet discovery announcement if the second determining unit has not yet made a packet discovery announcement determination at the time of the first determining unit determining packet discovery.

8. A packet detection method whereby a packet is detected from a received signal by using a preamble made up of an established, repeating training sequence added to the beginning of the packet, the method comprising the steps of:

calculating a first autocorrelation of the received signal over a first interval;

making a packet discovery determination on the basis of the result of comparing the first autocorrelation computed in the first autocorrelation calculating step to a first autocorrelation threshold value;

calculating a second autocorrelation of the received signal over a second interval equivalent to the interval length for packet discovery announcement; and

making a packet discovery announcement determination on the basis of the result of comparing the second autocorrelation computed in the second autocorrelation calculating step to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

9. A packet detection method whereby a packet is detected from a received signal by using a preamble made up of an established, repeating training sequence added to the beginning of the packet, the method comprising the steps of:

calculating the autocorrelation of the received signal for each repeating period of the established training sequence;

normalizing the autocorrelation computed in the autocorrelation calculating step to the average received signal power in a given interval;

calculating a first sum of the normalized autocorrelation obtained in the normalizing step and a number of delay signals wherein the normalized autocorrelation is successively delayed by one repeating period of the established training sequence, and wherein the number of delay signals is equal to the number of times the established training sequence is repeated;

making a packet discovery determination on the basis of the result of comparing the first normalized autocorrelation sum output in the first summing step to a first autocorrelation threshold value;

calculating a second sum of the normalized autocorrelation obtained in the normalizing step and a number of delay signals wherein the normalized autocorrelation is successively delayed by one repeating period of the established training sequence, up to a delay time equivalent to the interval length for packet discovery announcement; and

making a packet discovery announcement determination on the basis of the result of comparing the second normalized autocorrelation sum output in the second summing step to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

10. A wireless communication apparatus, comprising:

a receiver configured to receive a packet wherein a preamble made up of an established, repeating training sequence has been added to the beginning thereof;

a first autocorrelation calculator configured to solve for a first autocorrelation of a received signal over a first interval;

a first determining unit configured to make a packet discovery determination on the basis of the result of comparing the first autocorrelation calculated by the first autocorrelation calculator to a first autocorrelation threshold value;

a second autocorrelation calculator configured to solve for a second autocorrelation of the received signal over a second interval equivalent to the interval length for packet discovery announcement;

a second determining unit configured to make a packet discovery announcement determination on the basis of the result of comparing the second autocorrelation computed by the second autocorrelation calculator to a second autocorrelation threshold value lower than the first autocorrelation threshold value; and

a packet discovery announcement processor configured to conduct predetermined processing in accordance with the packet discovery announcement determination made by the second determining unit.

12. The wireless communication apparatus according to claim 10 or 11, wherein, in accordance with the packet discovery announcement, the packet discovery announcement processor outputs a CCA signal from the physical layer to the MAC layer or locks the AGC gain in the receiver.

11. A wireless communication apparatus, comprising:

a receiver configured to receive a packet wherein a preamble made up of an established, repeating training sequence has been added to the beginning thereof;

an autocorrelation calculator configured to solve for the autocorrelation of a received signal for each repeating period of the established training sequence;

a normalizer configured to normalize the autocorrelation computed by the autocorrelation calculator to the average received signal power in a given interval;

a plurality of serially-connected delay units each configured to apply delay equal to one repeating period of the established training sequence, wherein the number of delay units corresponds to the number of times the established training sequence is repeated;

a first summing unit configured to calculate the sum of the normalized autocorrelations respectively output from the normalizer and all of the serially-connected delay units;

a first determining unit configured to make a packet discovery determination on the basis of the result of comparing the first normalized autocorrelation sum output by the first summing unit to a first autocorrelation threshold value;

a second summing unit configured to calculate the sum of the normalized autocorrelations respectively output from the normalizer and a predetermined number of serially-connected delay units starting from the first;

a second determining unit configured to make a packet discovery announcement determination on the basis of the result of comparing the second normalized autocorrelation sum output by the second summing unit to a second autocorrelation threshold value lower than the first autocorrelation threshold value; and

a packet discovery announcement processor configured to conduct predetermined processing in accordance with the packet discovery announcement determination made by the second determining unit.

13. A wireless communication method, comprising the steps of:

receiving a packet wherein a preamble made up of an established, repeating training sequence has been added to the beginning thereof;

calculating a first autocorrelation of the received signal over a first interval;

making a packet discovery determination on the basis of the result of comparing the first autocorrelation calculated in the first autocorrelation calculating step to a first autocorrelation threshold value;

calculating a second autocorrelation of the received signal over a second interval equivalent to the interval length for packet discovery announcement;

making a packet discovery announcement determination on the basis of the result of comparing the second autocorrelation computed in the second autocorrelation calculating step to a second autocorrelation threshold value lower than the first autocorrelation threshold value; and

conducting predetermined processing in accordance with the packet discovery announcement determination made in the packet discovery announcement determining step.

14. A wireless communication method, comprising the steps of:

receiving a packet wherein a preamble made up of an established, repeating training sequence has been added to the beginning thereof;

calculating the autocorrelation of the received signal for each repeating period of the established training sequence;

normalizing the autocorrelation computed in the autocorrelation calculating step to the average received signal power in a given interval;

calculating a first sum of the normalized autocorrelation obtained in the normalizing step and a number of delay signals wherein the normalized autocorrelation is successively delayed by one repeating period of the established training sequence, and wherein the number of delay signals is equal to the number of times the established training sequence is repeated;

making a packet discovery determination on the basis of the result of comparing the first normalized autocorrelation sum computed in the first summing step to a first autocorrelation threshold value;

calculating a second sum of the normalized autocorrelation obtained in the normalizing step and a number of delay signals wherein the normalized autocorrelation is successively delayed by one repeating period of the established training sequence, up to a delay time equivalent to the interval length for packet discovery announcement;

and making a packet discovery announcement determination on the basis of the result of comparing the second normalized autocorrelation sum computed in the second summing step to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

15. A computer program stated in a computer-readable format so as to execute, on a computer, processing to detect a packet from a received signal by using a preamble made up of an established, repeating training sequence added to the beginning of the packet, the computer program causing the computer to execute the steps of:

calculating a first autocorrelation of the received signal over a first interval;

making a packet discovery determination on the basis of the result of comparing the first autocorrelation computed in the first autocorrelation calculating step to a first autocorrelation threshold value;

calculating a second autocorrelation of the received signal over a second interval equivalent to the interval length for packet discovery announcement; and

making a packet discovery announcement determination on the basis of the result of comparing the second autocorrelation computed in the second autocorrelation calculating step to a second autocorrelation threshold value lower than the first autocorrelation threshold value.

16. A computer program stated in a computer-readable format so as to execute, on a computer, processing to detect a packet from a received signal by using a preamble made up of an established, repeating training sequence added to the beginning of the packet, the computer program causing the computer to execute the steps of:

calculating the autocorrelation of the received signal for each repeating period of the established training sequence;

normalizing the autocorrelation computed in the autocorrelation calculating step to the average received signal power in a given interval;

calculating a first sum of the normalized autocorrelation obtained in the normalizing step and a number of delay signals wherein the normalized autocorrelation is successively delayed by one repeating period of the established training sequence, and wherein the number of delay signals is equal to the number of times the established training sequence is repeated;

making a packet discovery determination on the basis of the result of comparing the first normalized autocorrelation sum computed in the first summing step to a first autocorrelation threshold value;

calculating a second sum of the normalized autocorrelation obtained in the normalizing step and a number of delay signals wherein the normalized autocorrelation is successively delayed by one repeating period of the established training sequence, up to a delay time equivalent to the interval length for packet discovery announcement; and

making a packet discovery announcement determination on the basis of the result of comparing the second normalized autocorrelation sum computed in the second summing step to a second autocorrelation threshold value lower than the first autocorrelation threshold value.