An unbiased channel estimator for space-time block coding under Rayleigh fading

Abstract EN

-The performance of a supervised LMS adaptive channel estimator for space-time block coded systems (STBC) with two transmit antennas and one receive antenna is demonstrated.

The wireless channel statistic is Rayleigh with additive white Gaussian noise (AWGN) present at its output.

It is shown that it is possible to achieve an unbiased estimate when a single-tap estimator is used.

The two adaptive coefficients (due to employing transmit diversity) converge to the true channel gains owing to the orthogonality of the space-time block code.

This adaptive channel estimator results in zero mean square error (MSE) in the absence of noise.

The estimated channel gains are used in the STBC decoder to achieve decoding.

The algorithm is tested in the context of recovering images transmitted over the wireless channel with modulation and space-time block coding, and is characterized mainly by its simple implementation.

In addition, the single-tap estimator is shown to have a convergence time that is almost comparable to that of an N-tap estimator.

Although the latter converges somewhat faster, it has a non-zero MSE upon convergence.