Multipath Channel Tracking in OFDM Systems

High-quality channel estimation and tracking is central for coherent detection in wireless communication systems. Typical tracking algorithms assume the number of multipath components and delays to be known and constant, while their ampli- tudes may vary in time. In this work we focus on the more realistic assumption that also the number of channel taps is unknown and time-varying. The more complex estimation problem arising from this assumption is solved using Random-Set Theory, which allows one to regard the multipath-channel response as a single set-valued variable. Using a particle-filter implementation, we derive an estimator that simultaneously tracks the amplitudes and the number of channel taps for orthogonal frequency division multiplexed (OFDM) systems.