Joint Frame and Carrier Frequency Synchronization: Theoretical Considerations and Practical Trade-Offs

Abstract

In communication systems which transmit a continuous stream of data, the coded data symbols are typically transmitted in frames. Frames contain one or multiple blocks of coded data. The Start Of a Frame (SOF) is especially required to synchronize the decoder, especially in systems which use block codes such as Turbo and LDPC codes. This process is known as frame synchronization. We examine the general problem of frame synchronization in the presence of a carrier frequency offset. We first look at the theoretical formulation of the problem, and how the Maximum-Likelihood (ML) based solution is related to the classical periodogram. We then derive an improved ML based frame synchronizer for a commercial satellite waveform, which uses a non-standard SOF. Finally, we discuss implementation complexity and complexity reduction techniques of this new synchronizer on an FPGA.