Sub-optimum superimposed training design for estimating of mobile OFDM channels

Superimposed training (SIT) design for estimating of time-varying multipath channels is investigated for mobile orthogonal frequency division multiplexing (OFDM) systems. The design of sub-optimum SIT consists of two parts: the optimal SIT sequence is derived by minimizing the channel estimates´ mean square error (MSE); the sub-optimal power allocation between training and information data is developed by maximizing the averaged signal to interference plus noise ratio (SINR) under the condition of equal powered paths. The theoretical analysis is verified by simulations. For the metric of the averaged SINR against signal to noise ratio (SNR), the theoretical result matches the simulation result perfectly. In contrast to an interpolated frequency-multiplexing training (FMT) scheme or an SIT scheme with random pilot sequence, the SIT scheme with proposed sequence achieves higher SINR. The analytical solution of the proposed power allocation is demonstrated by the simulation as well.