Apparatus and method for measuring signal quality of a wireless communications link
First Claim
1. An apparatus for measuring signal quality in a communications link, the communications link capable of supporting transfer of OFDM symbols modulating data across a plurality of sub-carriers, the apparatus comprising:
- a link interface to receive an OFDM symbol from the communications link; and
a signal-to-noise ratio estimation unit to generate an estimate of a geometric signal-to-noise ratio for the OFDM symbol based on an average of a logarithmic difference between a soft decision and a hard decision for the OFDM symbol, the geometric signal-to-noise ratio estimate defining a scalar value of the communications link signal quality.
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Accused Products
Abstract
Techniques for measuring signal quality in a communications link supporting OFDM symbol transfer across plural sub-carriers are disclosed. These techniques employ a link interface receiving OFDM symbol(s) from the link, and a signal-to-noise ratio (SNR) estimation unit generating an estimate of a geometric SNR (SNRgeo) for the received symbols based on an average of the logrithmic difference between soft decision and hard decisions for the received symbol. SNRgeo here defines a scalar measure of the link signal quality, which results in a computationally efficient yet accurate link signal quality assessment, and thereby permit selective link characteristic alteration. Only sub-carrier subsets need be used to derive a relatively an accurate SNRgeo estimate. Sharing calculation resources between SNR estimation and soft decision units further reduce implementation complexity. Hard decision generation may use a relatively quick slicer or more accurate viterbi decoder/OFDM re-coder combination, as design goals dictate.
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Citations
68 Claims
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1. An apparatus for measuring signal quality in a communications link, the communications link capable of supporting transfer of OFDM symbols modulating data across a plurality of sub-carriers, the apparatus comprising:
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a link interface to receive an OFDM symbol from the communications link; and a signal-to-noise ratio estimation unit to generate an estimate of a geometric signal-to-noise ratio for the OFDM symbol based on an average of a logarithmic difference between a soft decision and a hard decision for the OFDM symbol, the geometric signal-to-noise ratio estimate defining a scalar value of the communications link signal quality. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A baseband processor capable of processing a baseband signal borne across a communications link, comprising:
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an FFT unit to recover a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; a soft decision unit responsive to said FFT unit to recover a soft decision of a transmitted symbol corresponding to the received symbol; a hard decision unit responsive to said soft decision unit to recover a hard decision of the transmitted symbol based on the soft decision; and a signal-to-noise ratio estimation unit to generate an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A transceiver, comprising:
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a receiver capable of receiving a baseband signal borne across a wireless communications link; and a baseband processor responsive to said receiver and comprising; an FFT unit to recover a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; a soft decision unit responsive to said FFT unit to recover a soft decision of a transmitted symbol corresponding to the received symbol; a hard decision unit responsive to said soft decision unit to recover a hard decision of the transmitted symbol based on the soft decision; and a signal-to-noise ratio estimation unit to generate an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A network interface apparatus, comprising:
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a transceiver, comprising; a receiver capable of receiving a baseband signal borne across a wireless communications link; and a baseband processor responsive to said receiver and comprising; an FFT unit to recover a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; a soft decision unit responsive to said FFT unit to recover a soft decision of a transmitted symbol corresponding to the received symbol; a hard decision unit responsive to said soft decision unit to recover a hard decision of the transmitted symbol based on the soft decision; a signal-to-noise ratio estimation unit to generate an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link; and a decoder responsive to said soft decision unit to recover data corresponding to the soft decision; and a network interface responsive to said decoder to receive the data, said network interface including a control unit responsive to said signal-to-noise estimation unit to selectively alter a characteristic of the communications link based on the geometric signal-to-noise ratio estimate generated by said signal-to-noise estimation unit.
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26. An information processing apparatus, comprising:
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an information processor; a transceiver responsive to said information processor and comprising; a receiver capable of receiving a baseband signal borne across a wireless communications link; and a baseband processor responsive to said receiver and comprising; an FFT unit to recover a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; a soft decision unit responsive to said FFT unit to recover a soft decision of a transmitted symbol corresponding to the received symbol; a hard decision unit responsive to said soft decision unit to recover a hard decision of the transmitted symbol based on the soft decision; a signal-to-noise ratio estimation unit to generate an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link; and a decoder responsive to said soft decision unit to recover data corresponding to the soft decision; and a network interface responsive to said decoder to receive the data and selectively transmit the data to said information processor, said network interface including a control unit responsive to said signal-to-noise estimation unit to selectively alter a characteristic of the communications link based on the geometric signal-to-noise ratio estimate generated by said signal-to-noise estimation unit.
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27. An apparatus for measuring signal quality in a communications link, the communications link capable of supporting transfer of OFDM symbols modulating data across a plurality of sub-carriers, the apparatus comprising:
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means for receiving an OFDM symbol from the communications link; and means for generating an estimate of a geometric signal-to-noise ratio for the OFDM symbol based on an average of a logrithmic difference between a soft decision and a hard decision for the OFDM symbol, the geometric signal-to-noise ratio estimate defining a scalar value of the communications link signal quality. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. A baseband processor capable of processing a baseband signal borne across a communications link, comprising:
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means for recovering a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; means for recovering a soft decision of a transmitted symbol corresponding to the received symbol; means for recovering a hard decision of the transmitted symbol based on the soft decision; and means for generating an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41)
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42. A transceiver, comprising:
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means for receiving a baseband signal borne across a wireless communications link; and baseband processor means, comprising; means for recovering a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; means for recovering a soft decision of a transmitted symbol corresponding to the received symbol; means for recovering a hard decision of the transmitted symbol based on the soft decision; and means for generating an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49, 50)
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51. A network interface apparatus, comprising:
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transceiver means, comprising; means for receiving a baseband signal borne across a wireless communications link; and baseband processor means, comprising; means for recovering a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; means for recovering a soft decision of a transmitted symbol corresponding to the received symbol; means for recovering a hard decision of the transmitted symbol based on the soft decision; means for generating an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link; and means for recovering data corresponding to the soft decision; and means for receiving the data, said data receiving means including means for selectively altering a characteristic of the communications link based on the geometric signal-to-noise ratio estimate generated by said generating means.
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52. An information processing apparatus, comprising:
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information processor means; transceiver means, comprising; means for receiving a baseband signal borne across a wireless communications link; and baseband processor means, comprising; means for recovering a received symbol from the baseband signal, the received symbol modulating data across a plurality of sub-carriers; means for recovering a soft decision of a transmitted symbol corresponding to the received symbol; means for recovering a hard decision of the transmitted symbol based on the soft decision; means for generating an estimate of a geometric signal-to-noise ratio for the received symbol based on an average of a logarithmic difference between the soft and hard decisions, the geometric signal-to-noise ratio estimate defining a scalar measure of signal quality for the communications link; and means for recovering data corresponding to the soft decision; and means for receiving the data and selectively transmitting the data to said information processor means, said data receiving means including means for selectively altering a characteristic of the communications link based on the geometric signal-to-noise ratio estimate generated by said generating means.
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53. A method for measuring signal quality in a communications link, the communications link capable of supporting transfer of OFDM symbols modulating data across a plurality of sub-carriers, the method comprising:
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receiving an OFDM symbol from the communications link; and generating an estimate of a geometric signal-to-noise ratio for the OFDM symbol based on an average of a logarithmic difference between a soft decision and a hard decision for the OFDM symbol, the geometric signal-to-noise ratio estimate defining a scalar value of the communications link signal quality. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60)
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61. A computer program product, comprising computer readable program code causing an information processor to perform the following steps support of measuring signal quality in a communications link, the communications link capable of supporting transfer of OFDM symbols modulating data across a plurality of sub-carriers, the steps comprising:
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receiving an OFDM symbol from the communications link; and generating an estimate of a geometric signal-to-noise ratio for the OFDM symbol based on an average of a logarithmic difference between a soft decision and a hard decision for the OFDM symbol, the geometric signal-to-noise ratio estimate defining a scalar value of the communications link signal quality. - View Dependent Claims (62, 63, 64, 65, 66, 67, 68)
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Specification