For the OFDM-based Amplify-and-Forward cooperative system, a novel relay-superimposed pilot strategy is proposed, where the\nsource pilot symbols are frequency divisionmultiplexed to estimate the cascaded channelwhile relay pilot sequence is superimposed\nonto the top of the cooperative data streamfor second-hop channel estimation. This method avoids the loss of data rate for additional\npilot subcarriers but results in the interference of unknown cooperative data. To remove the interference of cooperative data during\nthe estimation of second-hop channel, the Cooperative Interference Cancelation scheme assisted by cooperative data from direct\nlink is proposed.We derive the approximated lower bound for the MSE of second-hop channel estimation. Simulation results are\npresented to validate the performance of the proposed schemes.
Loading....