I am trying to solve this min-max problem.Please guide me how to approach this.
Please consider my Problem statement as:
Y=e * a ; where "e" & "a"=exponential phase factors & fixed complex numbers resp.
In Matlab;
M=4;N=256;
a = complex(randn(4,256),randn(4,256)); % coefficient matrix of "a"
... (1)
For a given θ the k-th row of (1) is:
What choice or what range of 
will minimize the peak of sum expression given in Eq. (2) ?
i.e.,
Subject to : 
and m=1,2,…M.