Phase noise estimation via adapted interpolation

Wideband communication systems operating at high SNR´s, like many point to point communication systems, generally suffer from poor oscillator phase noise characteristics. When QPSK pilot symbols are inserted periodically into a QAM data symbol stream, it is possible to obtain phase noise estimates for these time instants. Wiener interpolation is used to generate linear minimum mean-squared error (LMMSE) estimates for the time instants between those values. Finally, an adaptive scheme based on the well known least mean-squares (LMS) approach is presented. Using this adaptive method, the estimation algorithm converges to its optimum independently of the phase noise characteristic of a specific oscillator, or slowly varying temperatures