Mixed CSIT DL Channel: Gains with Interference Aware Receivers

Inhalt:
The broadcast channels (BC), a single transmitter transmitting data to multiple receivers, have been widely studied in literature mostly with and sometimes without the availability of channel state information at the transmitter (CSIT). We study a very practical version of the BC where the transmitter has CSIT of some users and no CSIT for other users. We look at the simplest instance of such a heterogeneous BC where a multi-antenna transmitter base-station (BS) is trying to communicate data to two single-antenna user equipments (UEs), having the perfect CSIT about UE-1 and no CSIT about UE-2. We propose a very simple transmission strategy at the BS combined with an intelligent interference-aware receiver at UE-2. We show that under the proposed transmission strategy, the sum rate can be significantly improved (unbounded in SNR) if low complexity interference-aware receiver is employed at UE-2 as compared to the case when UEs resort to suboptimal single-user detection where rates are bounded (in SNR). We then extend the proposed transmission strategy to long term evolution (LTE) scenario and show that the employment of interference aware receivers significantly improve performance in spite of the low resolution LTE precoders. It therefore underlines the necessity of intelligent receivers for modern wireless systems in the pursuit of high spectral efficiency.