Joint Estimation of Phase Noise and Channel Response for Broadband Communication Systems

Orthogonal frequency division multiplexing (OFDM) is an effective method to provide high bandwidth efficiency and to mitigate inter-symbol interference (ISI) in handling time dispersion of multi-path fading channels. However, one limitation of OFDM systems is that they are highly sensitive to the phase noise (PHN) caused by local oscillators (LO) which results in inter-carrier iterference (ICI). In this thesis, the basic concept of phase noise is studied including free-running oscillator and PLL synthesizer as the two popular PHN models. In our proposed method, we approximate phase noise by Fourier series. Based on the model, we propose a method to jointly estimate phase noise and channel response in time domain using pilots. The pilot is inserted in each OFDM block in order to estimate phase noise current waveform which is always changing as a random process (RP). Moreover, the proposed method is applied to Digital Video Broadcasting - Terrestrial (DVB-T) system as a broadcasting standard. It is shown by simulation results that our proposed method performs well for any channels as long as their order is not longer than cyclic prefix (CP).