The noisy MIMO interference channel with distributed CSI acquisition and filter computation

We study the frequency-flat noisy MIMO interference channel (IFC) without symbol extension and with initial assumption of no channel state information (CSI) neither at the base stations (BS) nor at the user equipments (UE). In the noisy IFC, interference is treated as noise and hence linear transmit (Tx) and receive (Rx) filtering is considered. A transmission strategy is proposed through which the BS and the UE get the necessary CSI for CSI based transmit and receive processing, by channel training and analog channel feedback, leading to transmission overhead. Both FDD and TDD scenarios are considered (the details for which are not too different in this distributed approach). In the limited overhead approach considered, discrepancies arise between the local estimates of the global CSI established at the various Tx/Rx units, on the basis of which the local Tx/Rx filters are computed. These filters are computed by optimizing a lower bound (and close approximation) of the weighted sum rate, accounting for partial CSI. The approach allows for simple approximate sum rate expressions that can easily be optimized for any set of system parameters to unveil the trade-off between the cost and the gains associated to CSI acquisition overhead. A centralized approach is briefly discussed also.