Learning Variable-Rate Codes for CSI Feedback.

We observe that current Deep Learning (DL)-based Channel State Information (CSI) encoder and decoder architectures achieve a distortion which is highly channel-dependent. To exploit this, we propose a novel learning-based variable-rate coding scheme to reduce overheads associated with CSI feedback. To that end, we propose an architecture which combines (alpha) training an efficient predictor for the distortion rate tradeoffs achievable for a given channel, and (b) optimization of a decision logic which allocates rates based on the predicted distortion. We evaluate our approach on various wireless channel datasets including the 3GPP 3D channel model and COST2100 with Massive MIMO channel model, and show significant potential reductions of up to 20% in the CSI feedback overhead.