% Number of BSs
L = 3;
% Number of users per cell
K = 2;
% Number of antennas at each BS
M = 4;
% Total number of users
U = L*K;
% Total number of transmit antennas
N = L*M;
% Total number of UAVs
Q = 2;
% Number of antennas on each UAV
S = 2;
% Total number of UAV antennas
P = S*Q;
% Maximum number of iterations
maxiter = 10;
% Power constraint at each BS (in watts)
Pmax = 1000;
% Total transmit power
Ptot = L*Pmax;
% Channel matrix H
H = randn(N, U) + 1i*randn(N, U);
% Channel matrix G for UAVs
G = randn(P, U) + 1i*randn(P, U);
% Additive white Gaussian noise (AWGN)
noise_power = 0.1;
noise = sqrt(noise_power/2)*(randn(U, 1) + 1i*randn(U, 1));
% Robust Precoding with UAVs (RSMA-UAV)
lambda = 1.0;
delta = 0.1;
% Initialize transmit precoders and equalizers
F = zeros(N, U);
alpha = zeros(P, U);
% Iterate until convergence or maximum number of iterations
for iter = 1:maxiter
% Update precoders and equalizers using MMSE estimator
F = (lambda*H'*H + (1-lambda)*eye(U)) \ (lambda*H'*(G*alpha) + noise);
alpha = (1/delta)*pinv(G*F)*(Ptot - sum(abs(G*F).^2, 1)');
end
% Calculate achievable rates
C = log2(det(eye(U) + (1/noise_power)*(H*F)*(G*alpha)*(G*alpha)'*(F'*H')/...
(eye(U) + (1/noise_power)*(H*F)*(H*F)')));
% Print out the achievable rates
fprintf('Achievable rates:\n');
for u = 1:U
fprintf('User %d: %.4f bps/Hz\n', u, C(u));
end
