Comparison of Feedforward Synchronization Schemes for Full-Response CPM Signals

We compare three non-data-aided synchronization techniques for full-response continuous phase modulation (CPM) signals, which have feedforward structures and are suitable for burst-mode transmissions. All the schemes are based on the statistical characteristics of the full-response CPM signals with modulation index h = 1, for which the algorithms are investigated to estimate the carrier frequency offset, carrier phase, and symbol timing. For the CPM signal with an arbitrary modulation index, the phase unwrapping technique is used to convert the modulation index into 1, and then, the proposed algorithms could work. The performances of the synchronization algorithms are investigated by simulations and compared with the modified Cramer-Rao bounds. It turns out that the estimation performances of the frequency offset and timing offset are close to the theoretical limits in high signal-to-noise ratio.