Synchronization of superimposed training for channel estimation

Iterative Synchronisation and DC-Offset Estimation using Superimposed Training

“…This is done in an iterative manner, where the equalised symbols (obtained through traditional ST in a first step) are fed back to the proposed ST synchronisation algorithm so that the data "noise" can be successively reduced, and hence achieve better synchronisation, DC-offset estimation, channel estimation and symbol detection. This new method for TSS gives a much better performance than the existing methods for ST synchronisation in [2], [4] and [5] in terms of the MSE of the channel estimates and the BER. Finally note that while [6] also describes a form of iterative ST (but different from that proposed here), it assumes perfect synchronisation exists.…”

“…Although synchronisation using ST was covered in [2], [4] and [5], it suffered from interference due to the transmitted information-bearing data. In this paper, we will remove the effect of the information data "noise" on the synchronisation process.…”

“…. , N − 1, b(k) is the information bearing sequence, h(k) is the channel impulse response, n(k) is the noise, d represents an unknown DC-offset term due to using first-order statistics [2], [4], and the integer τ s is the symbol synchronisation offset between the transmitter and the receiver. It is assumed that all terms in (1) are complex; that b(k) and n(k) are from independent, identically distributed respectively; and that the channel is of known order M − 1, i.e.…”

“…It should be noted that the method presented in [4] and [5] attempts synchronisation, but due to the interference from data and due to the presence of noise the TSS algorithm fails to correctly estimate the true synchronisation offset, which has the effect of delays/advances in the estimated channel impulse response and so this delay ambiguity also causes the equaliser output to be similarly delayed. Therefore [4] and [5] resort to estimating this (equalisation) delay by comparing the equalised sequence, shifted by different amounts, with the transmitted symbols {b(k)} in order to compute the BER.…”

“…P ≥ M . The use of HOS and polynomial rooting was avoided in the TSS method presented in [4], but required P ≥ 2M + 1. A lower complexity synchronisation algorithm was proposed in [5] based on structural properties of the vector containing the cyclic means of channel output.…”