Downlink Multiuser Hybrid Beamforming for MmWave Massive MIMO-NOMA System with Imperfect CSI

Algorithm 1

User clustering with beam and CQI.

Input and Initialization:

Input: the number of clusters , feedback beam and CQI value , for .

Initialize: .

where is the candidate set of user-pair that can be selected as a cluster. is the number of

selected clusters. A is the set of the strong users of the selected clusters. is the set of the

selected users in the l-cluster. is the set of weak users that have been selected.

Output:the user set selected for each cluster

Step (1) Select all user-pairs having a beam correlation higher than the threshold:

The BS sorts users according to the ascending CQI value: .

for = 1  :  K-1

for j = K  :  -1: i + 1

if   AND

break

end if

end for

end for

where is the predefined beam correlation threshold .

Step (2) Pair selection for clustering:

while  l < L

(a) Select the user-pair that has the maximum CQI value difference in :

(b) Put the selected user-pair having correlations with the users in A below the threshold into a new cluster:

if  

remove the pairs in that include user or

else

end if

end while

where is the predefined inter-cluster beam correlation threshold .