SINR measurement method for OFDM communications systems
First Claim
1. In a frame-based communications system utilizing orthogonal frequency division multiplexing (OFDM) and OFDM frames for multicarrier data transmission, each transmitted OFDM frame constructed from multiple time-domain OFDM symbols, one of the OFDM symbols being a known OFDM preamble, a method for measuring a signal to interference-plus-noise power ratio (SINR) for selected OFDM subchannel signals within the multicarrier data transmission to indicate channel quality and to adaptively adjust groupings of the OFDM subchannel signals to increase network capacity, the method comprising the steps of:
- computing a power spectral density (PSD) measurement vector Syy[n] from an OFDM preamble y[n] received in an nth OFDM frame;
computing a PSD measurement vector Sxx[n] from an OFDM preamble x[n] transmitted in the nth OFDM frame;
computing a cross-PSD measurement vector Sxy[n] between x[n] and y[n] for the nth OFDM frame;
computing a PSD measurement vector SSIG[n] for the nth OFDM frame using Sxx[n] and Sxy[n];
computing a PSD measurement vector SIPN[n] for the nth OFDM frame using Syy[n] and SSIG[n];
specifying a subchannel grouping vector G[n] for the nth OFDM frame;
computing a received signal power measurement vector PSIG[G[n]] for the subchannel grouping vector G[n] using SSIG[n];
computing a received IPN power measurement vector PIPN[G[n]] for the subchannel grouping vector G[n] using SIPN[n]; and
computing a received SINR measurement vector ρ
[G[n]] for the subchannel grouping vector G[n] using PSIG[G[n]] and PIPN[G[n]].
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Abstract
A signal to interference-plus-noise power ratio (SINR) measurement method for wireless communications systems which employ orthogonal frequency division multiplexing (OFDM) for multicarrier data transmission is disclosed. Fast-Fourier transform (FFT)-based SINR measurements can be computed on frame-by-frame or greater interval for individual or groupings of subchannel signals. Given a known transmitted time-domain OFDM frame preamble, and the corresponding channel and interference-plus-noise (IPN) corrupted received time-domain frame preamble, the disclosed method first computes the power spectral densities of the received signal of interest and of a received unwanted interference-plus-noise signal. The FFT-computed power spectral densities are then used to compute average received signal and received IPN power measurements for specified individual or groupings of OFDM subchannel signals. The power measurements are then frame-averaged using a recursive exponential smoothing method. The frame-averaged signal and IPN power measurements are then used to form quantized measurements of SINR for the specified OFDM subchannel signals of the received frame.
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Citations
30 Claims
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1. In a frame-based communications system utilizing orthogonal frequency division multiplexing (OFDM) and OFDM frames for multicarrier data transmission, each transmitted OFDM frame constructed from multiple time-domain OFDM symbols, one of the OFDM symbols being a known OFDM preamble, a method for measuring a signal to interference-plus-noise power ratio (SINR) for selected OFDM subchannel signals within the multicarrier data transmission to indicate channel quality and to adaptively adjust groupings of the OFDM subchannel signals to increase network capacity, the method comprising the steps of:
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computing a power spectral density (PSD) measurement vector Syy[n] from an OFDM preamble y[n] received in an nth OFDM frame; computing a PSD measurement vector Sxx[n] from an OFDM preamble x[n] transmitted in the nth OFDM frame; computing a cross-PSD measurement vector Sxy[n] between x[n] and y[n] for the nth OFDM frame; computing a PSD measurement vector SSIG[n] for the nth OFDM frame using Sxx[n] and Sxy[n]; computing a PSD measurement vector SIPN[n] for the nth OFDM frame using Syy[n] and SSIG[n]; specifying a subchannel grouping vector G[n] for the nth OFDM frame; computing a received signal power measurement vector PSIG[G[n]] for the subchannel grouping vector G[n] using SSIG[n]; computing a received IPN power measurement vector PIPN[G[n]] for the subchannel grouping vector G[n] using SIPN[n]; and computing a received SINR measurement vector ρ
[G[n]] for the subchannel grouping vector G[n] using PSIG[G[n]] and PIPN[G[n]]. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a frame-based communications system utilizing orthogonal frequency division multiplexing (OFDM) and OFDM frames for multicarrier data transmission, each transmitted OFDM frame constructed from multiple time-domain OFDM symbols, one of the OFDM symbols being a known OFDM preamble, a signal to interference-plus-noise power ratio (SINR) apparatus for measuring the SINR of selected OFDM subchannel signals within the multicarrier data transmission to indicate channel quality and for adaptively adjusting groupings of the OFDM subchannel signals to increase network capacity, the SINR measurement apparatus comprising:
a processor programmed for computing a power spectral density (PSD) measurement vector Syy[n] from an OFDM preamble y[n] received in an nth OFDM frame, computing a PSD measurement vector Sxx[n] from an OFDM preamble x[n] transmitted in the nth OFDM frame, computing a cross-PSD measurement vector Sxy[n] between x[n] and y[n] for the nth OFDM frame, computing a PSD measurement vector SSIG[n] for the nth OFDM frame using Sxx[n] and Sxy[n], computing a PSD measurement vector SIPN[n] for the nth OFDM frame using Syy[n] and SSIG[n], specifying a subchannel grouping vector G[n] for the nth OFDM frame, computing a received signal power measurement vector PSIG[G[n]] for the subchannel grouping vector G[n] using SSIG[n], computing a received IPN power measurement vector PIPN[G[n]] for the subchannel grouping vector G[n] using SIPN[n], and computing a received SINR measurement vector ρ
[G[n]] for the subchannel grouping vector G[n] using PSIG[G[n]] and PIPN[G[n]].- View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
Specification