Method and Receiver for Identifying a Leading Edge Time Period in a Received Radio Signal

• US 20090170458A1
• Filed: 07/19/2005
• Published: 07/02/2009
• Est. Priority Date: 07/19/2005
• Status: Abandoned Application

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Sahinoglu, Zafer, Molisch, Andreas F., Guvenc, Ismail
• Application Number:
  US11/995,394
• Publication Number:
  US 20090170458A1
• Time in Patent Office: Days
• US Class Current: 455/226.100
• CPC Class Codes: H04B 1/71637 Receiver aspects H04B1/7183 takes precedence
• CPC Class Codes: H04B 1/7183 Synchronisation

Abstract

A method for identifying a leading edge time period of a received radio signal includes identifying a greatest energy time period in a sequence of time periods. The received radio signal has a greatest average energy in the greatest energy time period. The method also includes identifying a least energy time period in the sequence of time periods. The received radio signal has a least average energy in the least energy time period. Further, the method includes setting a threshold energy based on the greatest average energy and the least average energy, determining a number of window time periods based on a characteristic of a radio channel used by the received radio signal, and identifying as a leading edge time period an earliest time period that precedes the greatest energy time period within the number of window time periods. The received radio signal in the leading edge time period has an average energy greater than or equal to the threshold energy.

Claims

1. A method for identifying a leading edge time period of a received radio signal, comprising:

identifying a greatest energy time period in a sequence of time periods, the received radio signal having a greatest average energy in the greatest energy time period;

identifying a least energy time period in the sequence of time periods, the received radio signal having a least average energy in the least energy time period;

setting a threshold energy based on the greatest average energy and the least average energy;

determining a number of window time periods based on a characteristic of a radio channel used by the received radio signal; and

identifying as a leading edge time period an earliest time period that precedes the greatest energy time period within the number of window time periods, and the received radio signal in the leading edge time period having an average energy greater than or equal to the threshold energy.

2. The method of claim 1, wherein the setting further comprises setting the threshold energy based on a normalized value between the greatest average energy and the least average energy.

3. A method for identifying a leading edge time period of a received radio signal, comprising:

identifying a greatest energy time period in a sequence of time periods, the received radio signal having a greatest average energy in the greatest energy time period; and

identifying as the leading edge time period a latest time period preceding the greatest energy time period immediately following a number of adjacent low energy time periods, the received radio signal having an average energy greater than or equal to a threshold energy in the leading edge time period, and the received radio signal having an average energy less than the threshold energy in each of the adjacent low energy time periods.

4. The method of claim 3, further comprising:

identifying a mean noise energy level and a noise energy variance of a radio channel used by the received radio signal; and

setting the threshold energy based on identified mean noise energy level and the noise energy variance of the radio channel.

5. The method of claim 4, wherein the setting further comprises:

setting the threshold energy ξ

, according to the following equation;

ξ

=σ

_edQ<sup>−

1</sup>(P_fa)+μ

_ed

wherein μ

_ed is mean noise energy level, σ

_ed is identified noise energy variance, P_fa is a probability of incorrectly identifying the leading edge time period, and Q is

$Q<br><br>\left(x\right)=\frac{1}{\sqrt{2<br><br><br><br>\mathrm{\pi <br><br>}}}<br><br>{\int <br><br>}_x^{\mathrm{\infty <br><br>}}<br><br>{\mathrm{<br><br>}}^{-t^2/2}<br><br><br><br><br><br>t.$

6. The method of claim 4, wherein the setting further comprises:

setting the threshold energy ξ

, according to the following equation;

$\mathrm{\xi <br><br>}={\mathrm{\sigma <br><br>}}_{\mathrm{ed}}<br><br>Q^{-1}<br><br>\left(1-{\left(1-P_{\mathrm{fa}<br><br>}\right)}^{\frac{1}{K}}\right)+{\mathrm{\mu <br><br>}}_{\mathrm{ed}}$

wherein μ

_ed is mean noise energy level, σ

_ed is identified noise energy variance, P_fa is a probability of incorrectly identifying the leading edge time period, and Q is

$Q<br><br>\left(x\right)=\frac{1}{\sqrt{2<br><br><br><br>\mathrm{\pi <br><br>}}}<br><br>{\int <br><br>}_x^{\mathrm{\infty <br><br>}}<br><br>{\mathrm{<br><br>}}^{-t^2/2}<br><br><br><br><br><br>t.$

7. The method of claim 3, further comprising:

predicting a number of signal clusters preceding the greatest energy time period based on a radio channel used by the received radio signal; and

setting the number of adjacent low energy time periods based on the number of signal clusters.

8. The method of claim 3, further comprising:

predicting a delay between signal clusters based on a radio channel used by the received radio signal; and

setting the number of adjacent low energy time periods based on the delay between signal clusters.

9. The method of claim 3, further comprising:

predicting a number of time periods per signal cluster based on a radio channel used by the received radio signal; and

setting the number of adjacent low energy time periods based on the number of time periods per signal cluster.

10. A receiver configured to identify a leading edge time period of a received radio signal, comprising:

a receiving section configured to identify a greatest energy time period in a sequence of time periods, the received radio signal having a greatest average energy in the greatest energy time period;

an identifying section configured to identify a least energy time period in the sequence of time periods, the received radio signal having a least average energy in the least energy time period;

a setting section configured to set a threshold energy based on the greatest average energy and the least average energy;

a determining section configured to determine a number of window time periods based on a characteristic of a radio channel used by the received radio signal; and

a leading edge identifying section configure to identify as a leading edge time period an earliest time period that precedes the greatest energy time period within the number of window time periods, and the received radio signal in the leading edge time period having an average energy greater than or equal to the threshold energy.

11. The receiver of claim 10, wherein the threshold setting section further comprises:

a normalized value setting section configured to set the threshold energy based on a normalized value between the greatest average energy and the least average energy.

12. A receiver configured to identify a leading edge time period of a received radio signal, comprising:

a greatest energy identifying section configured to identify a greatest energy time period in a sequence of time periods, the received radio signal having a greatest average energy in the greatest energy time period; and

a leading edge identifying section configured to identity as the leading edge time period a latest time period preceding the greatest energy time period immediately following a number of adjacent low energy time periods, the received radio signal having an average energy greater than or equal to a threshold energy in the leading edge time period, and the received radio signal having an average energy less than the threshold energy in each of the adjacent low energy time periods.

13. The receiver of claim 12, further comprising:

a noise identifying section configured to identify a mean noise energy level and a noise energy variance used by a radio channel used by the received radio signal; and

a threshold setting section configured to set the threshold energy based on identified mean noise energy level and the noise energy variance of the radio channel.

14. The receiver of claim 13, wherein the threshold setting section further comprises:

a threshold determining section configured to determine the threshold energy ξ

, according to the following equation;

ξ

=σ

_edQ<sup>−

1</sup>(P_fa)+μ

_ed

wherein μ

_ed is mean noise energy level, σ

_ed is identified noise energy variance, P_fa is a probability of incorrectly identifying the leading edge time period, and Q is

$Q<br><br>\left(x\right)=\frac{1}{\sqrt{2<br><br><br><br>\mathrm{\pi <br><br>}}}<br><br>{\int <br><br>}_x^{\mathrm{\infty <br><br>}}<br><br>{\mathrm{<br><br>}}^{-t^2/2}<br><br><br><br><br><br>t.$

15. The receiver of claim 13, wherein the threshold setting section further comprises:

a threshold determining section configured to determine the threshold energy ξ

, according to the following equation;

$\mathrm{\xi <br><br>}={\mathrm{\sigma <br><br>}}_{\mathrm{ed}}<br><br>Q^{-1}<br><br>\left(1-{\left(1-P_{\mathrm{fa}<br><br>}\right)}^{\frac{1}{K}}\right)+{\mathrm{\mu <br><br>}}_{\mathrm{ed}}$

wherein μ

_ed is mean noise energy level, μ

_ed is identified noise energy variance, P_fa is a probability of incorrectly identifying the leading edge time period, and Q is

$Q<br><br>\left(x\right)=\frac{1}{\sqrt{2<br><br><br><br>\mathrm{\pi <br><br>}}}<br><br>{\int <br><br>}_x^{\mathrm{\infty <br><br>}}<br><br>{\mathrm{<br><br>}}^{-t^2/2}<br><br><br><br><br><br>t.$

16. The receiver of claim 12, further comprising:

a cluster predicting section configured to predict a number of signal clusters preceding the greatest energy time period based on a radio channel used by the received radio signal; and

a time period setting section configured to set the number of adjacent low energy time periods based on the number of signal clusters.

17. The receiver of claim 12, further comprising:

a cluster predicting section configured to predict a delay between signal clusters based on a radio channel used by the received radio signal; and

a time period setting section configured to set the number of adjacent low energy time periods based on the delay between signal clusters.

18. The receiver of claim 12, further comprising:

a cluster predicting section configured to predict a number of time periods per signal cluster based on a radio channel used by the received radio signal; and

a time period setting section configured to set the number of adjacent low energy time periods based on the number of time periods per signal cluster.

19. A computer program product storing a program which when executed by a processor in a receiver configured to identify a leading edge time period of a received radio signal causes the processor to perform:

identifying a greatest energy time period in a sequence of time periods, the received radio signal having a greatest average energy in the greatest energy time period;

identifying a least energy time period in the sequence of time periods, the received radio signal having a least average energy in the least energy time period;

setting a threshold energy based on the greatest average energy and the least average energy;

determining a number of window time periods based on a characteristic of a radio channel used by the received radio signal; and

identifying as a leading edge time period an earliest time period that precedes the greatest energy time period within the number of window time periods, and the received radio signal in the leading edge time period having an average energy greater than or equal to the threshold energy.

20. A computer program product storing a program which when executed by a processor in a receiver configured to identify a leading edge time period of a received radio signal causes the processor to perform:

identifying a greatest energy time period in a sequence of time periods, the received radio signal having a greatest average energy in the greatest energy time period; and

identifying as the leading edge time period a latest time period preceding the greatest energy time period immediately following a number of adjacent low energy time periods, the received radio signal having an average energy greater than or equal to a threshold energy in the leading edge time period, and the received radio signal having an average energy less than the threshold energy in each of the adjacent low energy time periods.