MIMO channel estimation and tracking using a novel pilot expansion technique with Paley-Hadamard codes for future generation fast speed communications

A training-based MIMO channel estimation scheme is presented for future generation wireless systems that operate in both frequency and time selective fading channels. First, the method utilises pilot bits derived from the `Paley-Hadamard' matrix and exploit its orthogonal and `Toeplitz-like' structures to minimise the length of the training overhead. Secondly, by combining with a new pilot expansion technique, the method is able to estimate the length of the channel impulse response by flexibly extending its minimum pilot length as required in order to capture the number of multipath existed within the MIMO channel. Lastly, the pilot expansion technique can also help to reveal the initial channel variation and its Doppler rate which can be subsequently applied to the projection model in the Kalman filter for updating and tracking the MIMO channel in real-time with decision feedback during the actual data payload.