Double-chipwise correlation technique for efficient L2C signal acquisition

To further expedite L2C signal acquisition, in this article a double-chipwise correlation technique is developed. Inspired by the L2C signal structure that a civil moderate (CM) chip before multiplexing indeed represents the CM chip itself and a multiplexed civil long (CL) chip after multiplexing, the new technique accumulates the samples across the periods of a CM and a CL chip together. Compared with the recently proposed chipwise correlation technique, this new technique further reduces the correlation complexity of testing cells to half and decreases the code phases to test to half, at the expense of about 1.3 dB of detection performance loss on average. In addition, no extra operations are needed to deal with local CM code. Numerical results show that the new technique saves acquisition time significantly; for L2C signal received under clear sky conditions, the saving is about 75%.