  Unimodular/Phase only sequence having impulse like aperiodic auto-correlation
function plays a central role in the applications of RADAR, SONAR,
Cryptography, and Wireless (CDMA) Communication Systems. In this paper, we
propose a fast iterative algorithm to design phase only sequences of arbitrary
lengths by minimizing the Integrated Side-lobe Level (ISL) metric, which is
very closely related to the auto-correlation property of a sequence. The ISL
minimization problem is solved iteratively by using the
Majorization-Minimization (MM) technique, which ensures a monotonic convergence
to the stationary minimum point. To highlight the performance of a proposed
algorithm, we conduct the numerical experiments for different sequence lengths
using different initializations and also compare them with the existing
algorithms. Numerical simulations show that irrespective of the sequence length
and initialization, the proposed algorithm is performing better than the
state-of-the-art algorithms in terms of speed of convergence. We also show a
computationally efficient way to implement our proposed algorithm by using the
FFT and IFFT operations.
