Method and apparatus for acquisition and tracking of orthogonal frequency division multiplexing symbol timing, carrier frequency offset and phase noise

• US 8,300,743 B1
• Filed: 02/26/2009
• Issued: 10/30/2012
• Est. Priority Date: 03/05/2001
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Narasimhan, Ravi
• Primary Examiner(s): Torres, Juan A
• Application Number:
  US12/393,547
• Time in Patent Office: 1,342 Days
• Field of Search: 375/346
• US Class Current: 375/346
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 27/2659 Coarse or integer frequency offset determination and synchronisation
• CPC Class Codes: H04L 27/266 Fine or fractional frequency offset determination and synchronisation
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 27/2695 with channel estimation, e.g. determination of delay spread, derivative or peak tracking channel estimation H04L25/0202

Abstract

A method for updating channel estimates in an orthogonal frequency division multiplexing receiver of a wireless local area network includes generating channel estimates for an orthogonal frequency division multiplexing subcarrier as a function of subcarrier index values. The method includes generating a complex number by summing a product of frequency domain signals and the channel estimates for each of the subcarrier index values and dividing the sum by a sum of a squared absolute value of the channel estimate for each of the subcarrier index values. The method includes multiplying the complex number by the channel estimates to generate updated channel estimates.

Claims

1. A method for updating channel estimates in an orthogonal frequency division multiplexing receiver of a wireless local area network, comprising:

generating channel estimates for an orthogonal frequency division multiplexing subcarrier as a function of subcarrier index values;

generating a complex number by summing a product of frequency domain signals and said channel estimates for each of said subcarrier index values and dividing said sum by a sum of a squared absolute value of said channel estimate for each of said subcarrier index values; and

multiplying said complex number by said channel estimates to generate updated channel estimates.

2. The method of claim 1 further comprising using said updated channel estimates in a frequency equalizer for data detection.

3. A channel estimate updating circuit for an orthogonal frequency division multiplexing receiver of a wireless local area network, comprising:

channel estimate generating means for generating channel estimates for an orthogonal frequency division multiplexing subcarrier as a function of subcarrier index values;

complex number generating means for generating a complex number by summing a product of frequency domain signals and said channel estimates for each of said subcarrier index values and dividing said sum by a sum of a squared absolute value of said channel estimate for each of said subcarrier index values; and

first multiplying means for multiplying said complex number by said channel estimates to generate updated channel estimates.

4. The channel estimate updating circuit of claim 3 wherein said updated channel estimates are used in a frequency equalizer for data detection.

5. A channel estimate updating circuit for an orthogonal frequency division multiplexing receiver of a wireless local area network, comprising:

a channel estimator that generates channel estimates for an orthogonal frequency division multiplexing subcarrier as a function of subcarrier index values;

a complex number generator that generates a complex number by summing a product of frequency domain signals and said channel estimates for each of said subcarrier index values and dividing said sum by a sum of a squared absolute value of said channel estimate for each of said subcarrier index values; and

a first multiplier that multiplies said complex number by said channel estimates to generate updated channel estimates.

6. The channel estimate updating circuit of claim 5 wherein said updated channel estimates are used in a frequency equalizer for data detection.