A de-correlated delay locked loop for direct sequence spread spectrum systems in a multi-user environment

Abstract

Traditional delay locked loops are well-proven techniques for tracking the pseudo noise sequence for a single user condition. However, serious degradations may occur in a multi-user environment. For example, the loop may become unstable under conditions of large multiple access interference. A novel de-correlated delay locked loop is presented for synchronous direct sequence spread spectrum systems. It de-correlates the MAI caused by interfering users at the zero timing offset instant and achieves a better S curve. Computer simulations based on Gold code sequences are used to verify the results.