Fig. 1From: Channel estimation for FDD massive MIMO system by exploiting the sparse structures in angular domainNormalized amplitudes for the elements of angular-domain channel matrix Xk, where N=64, M=4, and θk=15.5°. The angular spread for AoD is δd=5°. It is assumed that the waves arriving at the user are usually uniformly distributed in AoA [12]. Therefore, Δa is equal to πBack to article page