Efficiently All-Digital Code Tracking for Band-Limited DSSS Systems

In this letter, we have studied the all-digital code tracking problem for band-limited direct sequence spread spectrum (DSSS) systems. Band-limited DSSS systems have many advantages over rectangular-pulse DSSS systems. However, the current all-digital code tracking methods for band-limited DSSS systems have more computational complexity than the latter. Therefore, we propose an efficiently all-digital code tracking method for band-limited DSSS systems where we implement despreading in the frequency domain with others and take advantage of the narrow time-width characteristic of the signal autocorrelation to achieve a lower complexity and constant tracking performance, i.e., the constant steady-state time-delay error variance at the same time. We also give a closed-form expression of the steady-state time-delay error variance of the proposed method in this letter, which can be used to analyze the performance of the proposed method theoretically and design proper band-limited DSSS systems. The theoretical analysis and simulation results show that the proposed method has lower computational complexity and constant tracking performance.