# CDMA Signature Sequences with Low Peak-To-Average Ratio via Alternating Projection

#### Joel Tropp, Inderjit Dhillon, Robert Heath Jr., Thomas Strohmer

Abstract:   Several algorithms have been proposed to construct optimal signature sequences that maximize the sum capacity of the uplink in a direct-spread synchronous code division multiple access (CDMA) system. These algorithms produce signatures with real-valued or complexvalued entries that generally have a large peak-to-average power ratio (PAR). This paper presents an alternating projection algorithm that can design optimal signature sequences that satisfy PAR side constraints. This algorithm converges to a fixed point, and these fixed points are partially characterized.