Bandwidth efficient 3D pilot design for MIMO-OFDM

We address pilot aided channel estimation (PACE) for MIMO-OFDM operating in diverse deployment scenarios, ranging from outdoor macro-cells to indoor office environments. In macro-cells high mobile velocities and large cell sizes result in high Doppler and channel delay spreads, while transmit antenna elements are typically spatially correlated. On the other hand, in indoor environments spatial correlation tends to be low, while cell sizes together with mobile velocities are substantially smaller. In this work the deployment specific correlations in time, frequency and space are exploited for the design of a bandwidth efficient three dimensional (3D) pilot grid. The associated channel estimation procedure is based on the principle of channel estimation by interpolation in three dimensions time, frequency and space.