Self-encoded spread spectrum for GNSS applications

Self-encoded spread spectrum systems derive spreading codes from the data stream and have been shown to achieve a 3 dB power gain while providing time diversity for robust performance in wireless fading channels. Since the receiver does not knowledge of the initial spreading code, these systems present a unique challenge to code synchronization. In this paper, we present a method to achieve code acquisition. The receiver employs chip-offset correlation to provide a reliable estimate of the initial code from the spread spectrum signal. A method for tracking signal timing is also explored. This method is also extended to take advantage of the unique features of SESS. Simulations show that accurate timing information can be obtained both from correlation and iterative detection, with the combined detection providing a 3dB improvement in timing tracking for GNSS applications.