Approximate Maximum Likelihood Ratios for Sequential Code Acquisition

In this paper, we consider the noncoherent code acquisition problem using sequential schemes. Since code acquisition schemes using the maximum likelihood estimate usually require a high level of computational complexity, simplified schemes are proposed and analyzed based on approximations. The performance of the simplified and original code acquisition schemes are compared in additive white Gaussian noise and slowly-varying fading channels. Numerical results show that the proposed schemes have essentially the same performance as the original schemes while allowing simpler structures.