Foresighted delayed CSIT feedback for finite rate of innovation channel models and attainable NetDoFs of the MIMO interference channel

Channel State Information at the Transmitter (CSIT) is of utmost importance in multi-user wireless networks, in which transmission rates at high SNR are characterized by Degrees of Freedom (DoF, the rate prelog). In recent years, a number of ingenious techniques have been proposed to deal with delayed and imperfect CSIT. In this paper we consider Finite Rate of Information (FRoI) channel models (CM) introduced earlier, which captures the DoF of the channel coefficient time series. Both the block fading model and the stationary bandlimited channel model are special cases of the FRoI CM. However, the fact that FRoI CMs model stationary channel evolutions allows to exploit one more dimension: arbitrary time shifts. In this way, the FroI CM allows Foresighted Channel Feedback (FCFB) which provides CSIT at all times, even in the presence of CSIT FB delay, by increasing the FB rate. DoF-optimal schemes in the presence of perfect CSIT then maintain optimal DoF when combined with FCFB. This is applicable to any multi-user network. In this paper we analyze NetDoFs, which account for training overhead and FB DoF consumption on the reverse link. We provide attainable NetDoF expressions in the MIMO Interference Channel (IC) with linear transceivers for the DoF-optimal schemes of Interference Alignment (IA) with FCFB and several simpler schemes. Numerical evaluations show that the attainable NetDoF may be far away from the DoF and that simpler schemes may be close to optimal in terms of NetDoF.