A Robust Channel Estimation Scheme for 5G Massive MIMO Systems

Algorithm 1

M-JOMP algorithm.

	Input: , , , according to Equation (7), calculate the measured value and the measurement matrix , and initialize the residual signal Let the common support set of the channels , and set the number of iterations to 1.
(1)	From , the BS selects the position corresponding to the previous maximum values as the support index to join the support set .
(2)	The BS update the common support set by Equation (10).
(3)	Let if , then , return to Step 1, otherwise go to Step 4.
(4)	BS obtains partial joint support channel estimation by Equation (13) transmitted by the UE.
(5)	Let the unique support set of the channel , the residual signal , set the number of iterations to 1.
(6)	From , the position corresponding to the previous maximum values is selected by the BS as a supporting index and added to the support set .
(7)	Let , according to , the position corresponding to the previous maximum values is added as a supporting index to the support set at the BS.
(8)	Let , if , let , return to Step 6, otherwise, go to Step 9.
(9)	The BS obtains a unique support channel estimate by Equation (14).
	Output: According to Equation (15), the channel estimate (CSI) at the BS in the angular domain can be obtained, and then,