A Modified De-Correlated Delay Lock Loop with Better Static Response for Synchronous DS-CDMA Systems

In this paper we present a modified de-correlated delay lock loop (MD-DLL) for synchronous direct-sequence code division multiple access (DS-CDMA) systems. With appropriate choice of weighting and offset parameters of the local signals, the proposed MD-DLL scheme solves the tracking bias problems in de-correlated delay lock loop (D-DLL) under low SNR condition. By diminishing multiple access interference (MAI) at the on-time code position instant and minimizing the weighting imbalance between the two local signals, it is shown that MD-DLL achieves a better S-curve with negligible tracking bias and good near far resistance compared with the traditional delay lock loop (T-DLL) and D-DLL. Computer simulations based on Gold code sequences are used to verify the findings.