One way is to set the DisplayName of each line when you plot it:
names = {
'phi = 0 & psi = 0'
'phi = psi'
'phi = [0,5,10,15,20,25,30] & psi = 0'
'phi = 0 & psi = [0,5,10,15,20,25,30]'
'phi = [0,5,10,15,20,25,30] & psi = [0,5,10,15,20,25,30]'
};
hold on % do "hold on" before you plot
for ii = 1:5
plot(rand(1,10),rand(1,10),'DisplayName',names{ii}); % (plotting random data because I don't have your data)
end
xlabel('X (m)');
ylabel('Received power (dBm)');
legend();
