Phase tracking performance and code reuse plan theory in asynchronous multirate CDM

First, Dynamic Partial Correlation (DPC) method to solve the cross correlation between Pseudo-Noise (PN) codes is proposed under the asynchronous multirate Code Division Multiple Access (CDMA) system with asynchronous air interface. Dynamic Partial Correlation (DPC) helps to evaluate the autocorrelation of multirate cross-correlation terms and the corresponding power spectrum density (PSD) in the presence of multirate multiple access interference (MMAI) and additive white gaussian noise (AWGN) under fading channel environment. It is applied to analyze the code phase tracking performance of coherent Delay-Locked Loop (DLL) and carrier phase synchronization of digital Phase-Locked Loop (PLL). Second, the novel Hybrid Pseudo-Noise (HPN) code wherein the code-words are designed to possess zero mutual cross-correlations, thereby enabling interference suppression (or complete cancellation under appropriate code assignment to neighboring cells) in asynchronous CDMA systems is proposed. Basic Code (BC) assignment strategies (to assign BCs to adjacent cells) which exploit the capabilities of the HPN code to the maximum possible extent are illustrated. With proper code assignments to neighboring cells, the HPN code is shown to significantly enhance the performance of both the up as well as down links (when compared with conventional Gold code). The experimental data demonstrates that the proposed code could be successfully deployed in third generation CDMA systems.