Carrier and Symbol Synchronization Hardware Software Co-design Final Project R 楊進發 R 楊雅嵐 R 陳宴毅

Outline Introduction Clock error & Frequency error Carrier Recovery & Sampling Recovery Implement Result Conclusion Reference

Introduction Wireless communication has received much attention from researchers working on personal communication systems in recent years. We have observed that in a digital communication system, the output of the demodulator must be sampled periodically, once per symbol interval, in order to recover the transmitted information.

Introduction (cont’) Since the propagation delay from the transmitter to the receiver is generally unknown at the receiver, symbol timing must be derived from the received signal in order to synchronously sample the output of the demodulator. The propagation delay in the transmitted signal also results in a carrier offset, which must be estimated at the receiver if the detector is phase- coherent.

Frequency error Caused by mismatch of carrier and Doppler shift ΔωT ω 0 + Δω ω0ω0

Clock error Caused by clock signal mismatch and Doppler shift → Correct sampling clock --> Incorrect sampling clock

Carrier Frequency Recovery Carrier recovery is to synchronize the locally generated carrier with the carrier contained in the received input. This can eliminate crosstalk between I and Q channel data, thus increasing output SNR.

Carrier Frequency Recovery (cont’) QPSK Decision-Directed Costas Loop

Timing Recovery To find the correct timing for sample-and-hold or integrate-and-dump devices in the receiver.

Timing Recovery (cont’) Sample-Derivative Timing Recovery Loop

Implement QPSK Transceiver Signal

Implement (cont’) Carrier frequency offset and timing offset

Implement (cont’) Carrier frequency recovery

Implement (cont’) Sampling Recovery

Result ․ QPSK Transceiver Signal

Result (cont’) Carrier frequency offset and timing offset

Result (cont’) Carrier frequency recovery

Result (cont’) Sampling Recovery

Conclusion Carrier recovery and timing synchronization are two topics that have been thoroughly investigated over the past three decades. Symbol synchronization is required in every digital communication system which transmits information synchronously.

Reference Jen-Shi Wu, Ming-Luen Liou, His-Pin Ma and Tzi-Dar Chiueh, “A 2.6V 44MHz all-digital QPSK direct-sequence spread-spectrum transceiver IC,” IEEE J. Solid-State Circuits, vol. 32,No. 10, Oct John G. Proakis, Digital Communications, McGraw Hill. R. L. Peterson, Introduction to Spread Spectrum Communications, Prentice Hall, Baseband Communication VLSI Lab.