In [14], the linear minimum mean square error (LMMSE) channel estimation method based on channel autocorrelation matrix in frequency domain has been proposed.
When the channel estimation is imperfect, the interference at the users cannot be removed, since the precoding matrices are derived based on channel estimates.
Where (e) comes from the fact of (11), (f) follows the fact that ((bar {mathbf {u}}_{k}^{d},bar {mathbf {v}}_{i}^{j})) is designed based on quantized channel matrix (bar {mathbf {H}}_{k,i}) with IA approach.
Based on the channel matrix ({mathbf {H}}^{(d)}) (as defined in (7)), each potential relay can calculate the residual interference power associated with its link and use a distributed relay selection algorithm to find the optimal relay.
One constraint of the system under consideration is that the receiver can only access a linear combination of the receive antenna outputs, which makes the traditional antenna selection schemes based on the channel matrix not applicable.
Thereby, G q, 2 ( p ) is obtained as G q, 2 ( p ) = V q, 2, 1 ( p ). Step 4: Update the decoding matrix based on the equivalent channel matrix after the cancelation of the intrinsic interference where only the processing at the transmitter is considered H ~ etx q ( p ) = Re H q F q G q ( p ) ∈ R M R q × d q. (20).
Moreover, the PA matrix is derived based on the compound channel matrix from all the cooperative nodes to the user.
Based on this aggregated channel matrix, the CCN obtains the precoding weights, consisting of the beamforming weights after power allocation.
The estimate of the signal vector of branch l, (hat {mathbf {x}}_{n}^{(l)}), is obtained using a SIC receiver based on a new channel matrix (check {mathbf {H}}_{n}^{(l)} =check {mathbf {H}}_{n}mathbf {P}_{n}^{(l)}).
