A robust phase detection structure for M-PSK: theoretical derivations, simulation results, and system identification analysis

Abstract

In this paper we shall present a new non data aided (NDA) adaptive phase detection structure for carrier synchronization phase locked loops (PLLs) in M-ary phase shift keying (M-PSK) receivers. The structure's principal novelty is in the fact that it dynamically adapts the phase detector's S-curve to allow the PLL to perform optimally at virtually any input signal-to-noise ratio (SNR) at which it can sustain lock. Investigation of the detector will commence with theoretical derivations of its S-curve, self-noise, and phase-error variance performance. These theoretical predictions will then be verified by computer simulations. As a third method of analysis, simulated PLLs employing the new detector will be investigated using the Steiglitz-McBride system identification algorithm, which will prove that those PLLs indeed perform optimally at every SNR. The theoretical, simulation, and system identification investigations of the proposed structure will be contrasted with results obtained using other NDA and decision directed (DD) phase detectors. As those comparisons will show, the proposed detection scheme offers greatly improved phase-error variance performance as well as superior resistance to fading and to automatic gain control (AGC) imperfections. Moreover, the new detector has a very compact hardware implementation