Iterative Channel Estimation for DOCSIS 3.1 Uplink Channels

Abstract

This paper presents an OFDMA channel estimation technique that jointly considers the effects of coarse timing error and multipath propagation. Many conventional approaches only consider an optimistic scenario where timing synchronization is perfect and each of the channel delays is an integer number of system samples. In realistic scenarios, timing offsets and echo delays are not integer multiples of the system's sampling period. This threatens sub-carrier orthogonality and causes leakage in the discrete Fourier transform (DFT)-based channel estimation method. Such leakage leads to poor estimation and consequently reduces the system's overall performance. Proposed in this paper is a novel iterative channel estimation technique that considers the practical scenario of fractional timing error and non sample-spaced echo delays. The proposed method does not require channel state information (e.g. second-order statistics of the channel impulse responses or the noise power). Simulation shows that, when comparing OFDMA channel estimation techniques under DOCSIS 3.1 realistic channel conditions, the proposed algorithm significantly outperforms all conventional methods known to the authors.