Timing Recovery and Carrier Synchronization Using LDPC Codes

This book provides techniques for symbol tracking and carrier acquisition in a Low-Density Parity-Check (LDPC) coded transmission. In traditional receiver architectures acquisition and tracking are performed using phase-lock techniques that are independent of the channel-code decoding process. In burst reception scenarios bandwidth inefficient piloting must often be embedded in a transmission in order to accelerate acquisition to aid symbol time tracking at low signal-to-noise ratios. In this book we show that outputs from an iterative decoder can be used to improve the estimation of symbol frequency and phase in either a pilotless environment or complementing available pilot information. We describe a method capable of handling very large offsets with complexity that grows linearly with the maximum offset size. Combining information from the set of parity-check equations of a LDPC code observations with a properly calibrated phase locked loop allows successful tracking in very high noise scenarios. The problem of carrier frequency estimation under these high noise conditions is also addressed.