Normalized auto-correlators

• US 7,660,371 B2
• Filed: 09/07/2006
• Issued: 02/09/2010
• Est. Priority Date: 09/07/2006
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Gurevitz, Assaf, Perlmutter, Uri
• Primary Examiner(s): Torres; Juan A
• Application Number:
  US11/516,902
• Publication Number:
  US 20080063094A1
• Time in Patent Office: 1,251 Days
• Field of Search: 375/340
• US Class Current: 375/340
• CPC Class Codes: H04L 27/2649 Demodulators
• CPC Class Codes: H04L 27/2656 Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
• CPC Class Codes: H04L 27/2676 Blind, i.e. without using known symbols

Abstract

Embodiments of methods and systems for auto-correlating wireless signal samples are provided. Such embodiments include local normalization of each signal sample by a root mean square level of samples that preceded it, prior to any summation of the auto-correlation procedure. These auto-correlated signal samples are then used to distinguish downlink from uplink signals present within the signal sample set. Other embodiments include auto-correlation techniques in which no normalization is performed at any time with respect to the summation procedure. Such auto-correlated samples are then scanned to detect a preamble symbol or symbols within the signal samples. Reliable and expeditious wireless communications under WiMAX 802.16e and other protocols can be achieved in accordance with the present embodiments.

Claims

1. A method, comprising:

storing, in a memory, instructions for performing the method;

executing the instructions on a processor;

according to the instructions being executed;

auto-correlating a plurality of signal samples from a signal by;

normalizing each of the plurality of signal samples by a root mean square level of a distance between correlated samples that preceded individual signal samples; and

summing the plurality of normalized signal samples;

wherein the auto-correlating is performed in accordance with the expression;

2. The method of claim 1, wherein:

the signal includes a cyclic prefix length; and

the method further comprises not including the cyclic prefix length as a term in the summation.

3. The method of claim 1, wherein the signal is defined by an orthogonal frequency-division multiplexing access (OFDMA) signal.

4. The method of claim 1, wherein the signal is defined by a WiMAX 802.16e down link signal.

5. The method of claim 1, further comprising distinguishing a downlink signal from an uplink signal by way of the auto-correlating.

6. A computer-readable storage media encoded with a program code, the program code configured to cause one or more processors to auto-correlate a plurality of signal samples from a signal by:

normalizing each of the plurality of signal samples by a root mean square level of a distance between correlated samples that preceded individual signal samples; and

summing the plurality of normalized signal samples;

wherein the program code is further configured to cause the one or more processors to auto-correlate the plurality of signal samples in accordance with the expression;

7. The computer-readable storage media of claim 6, wherein the program code is further configured to process signal samples comprising orthogonal frequency-division multiplexing access (OFDMA) signals.

8. The computer-readable storage media of claim 6, wherein the program code is further configured to process signal samples comprising a WiMAX 802.16e down link signal.

9. The computer-readable storage media of claim 6, wherein the program code is further configured to cause the one or more processors to distinguish a downlink signal from an uplink signal by way of the auto-correlation.