Doppler spread/velocity estimation in mobile wireless communication devices and methods therefor
AssigneeMotorola, Inc.
InventorsAlexandre Mallette, John Paul Oliver
Life of this patent
Estimating the term…
Abstract
A method for estimating Doppler spread in mobile wireless communication devices, for example in CDMA or W-CDMA cellular communication systems, with improved noise immunity. The Doppler spread estimation is based on an estimated value of an autocorrelation or autocovariance at a first lag (210) and at a second lag (220), the magnitude of which is greater than the first lag. A first ratio is determined (250) between a first difference (230) and a second difference (240). The estimated Doppler spread is generally proportional to a square root (260) of the first ratio, and is scaled (270) by a multiplicative factor that depends on whether the estimated function is an autocorrelation or autocovariance function.
Claims24
A method for estimating Doppler spread in a mobile wireless communication device, comprising:
- estimating a value of an estimated autocorrelation of an impulse response of a channel for first and second lags, the second lag having a magnitude greater than a magnitude of the first lag;
- determining a first ratio between a first difference and a second difference,
- the first difference is a difference between the estimated value at the first lag and the estimated value at the second lag,
- the second difference is a difference between a first product and a second product, the first product is a product of the second lag squared and the estimated value at the first lag, the second product is a product of the first lag squared and the estimated value at the second lag;
- determining a square root of the first ratio if the first ratio is greater than zero;
- determining Doppler spread proportional to the square root of the first ratio.
A method for estimating Doppler spread in a mobile wireless communication device, comprising:
- estimating a value of an estimated autocovariance of a magnitude squared of an impulse response of a channel for a first non-zero lag and for a second lag, the second lag having a magnitude greater than a magnitude of the first lag;
- determining a first ratio between a first difference and a second difference,
- the first difference is a difference between the estimated value at the first lag and the estimated value at the second lag,
- the second difference is a difference between a first product and a second product, the first product is a product of the second lag squared and the estimated value at the first lag, the second product is a product of the first lag squared and the estimated value at the second lag;
- determining a square root of the first ratio if the first ratio is greater than zero;
- determining Doppler spread proportional to the square root of the first ratio.
A mobile wireless communication device, comprising:
- means for determining a square root of a first ratio greater than zero,
- the first ratio defined by [φ(n)−φ(m)]/[m2φ(n)−n2φ(m)],
- where φ(n) is an estimated value of an estimated autocorrelation of an impulse response of a channel at a first lag, n, φ(m) is an estimated value of the estimated autocorrelation at a second lag, m,
- a magnitude of the second lag m greater than a magnitude of first lag n;
- means for determining Doppler spread proportional to a square root of the first ratio if the first ratio is greater than zero.
A mobile wireless communication device, comprising:
- means for determining a square root of a first ratio greater than zero,
- the first ratio defined by [φ(n)−φ(m)]/[m2φ(n)−n2φ(m)],
- where φ(n) is an estimated value of an estimated autocovariance from a magnitude squared of an impulse response of a channel at a first non-zero lag, n,
- φ(m) is an estimated value of the estimated autocovariance at a second lag, m,
- a magnitude of the second lag m greater than a magnitude of first lag, n;
- means for determining Doppler spread proportional to a square root of the first ratio if the first ratio is greater than zero.
Dependencies are inferred from the claim text.