A hybrid Cramér-Rao bound for the channel estimation of non-orthogonal, disintegrated, amplify-and-forward cooperative OFDM systems

In this paper, a hybrid Cramér-Rao bound (HCRB) for the channel estimation of non-orthogonal, disintegrated, amplify-and-forward (NAF) relaying systems is derived. The HCRB is an effective benchmark for examining channel estimation performance. Several conventional frequency-domain channel estimations, such as the least-squares (LS), minimum-mean-square-error (MMSE) channel estimators are simulated and compared with the derived HCRB.