Outage-Constrained Beamforming for Two-Tier Massive MIMO Downlink with Pilot Reuse

Algorithm 1

(1) Set , , , ,

        and .

(2) while    and    do

(3)  Solve at each SBS, and transfer to MBS,

(4)  Solve at MBS, calculate and ,

(5)  Transfer to SBSs and let ,

(6)  Update ,

               and ,

(7) end while