Predictive Quantization and Joint Time-Frequency Interpolation Technique for MIMO-OFDM Precoding

Agrim Gupta, Kumar Appaiah, Rahul Vaze

Abstract: Precoding transmissions in wireless MIMO systems is essential to enable optimal utilization of the spatial degrees of freedom. However, communicating the precoding matrices from the receiver is challenging, owing to large feedback requirements. Past work has shown that predictive quantization in time, as well as interpolation over frequency can be used to reconstruct the precoders over a wide band, although these techniques have not been used jointly. We propose both a predictive quantization as well as a joint time-frequency interpolation strategy for precoding matrices over the Stiefel manifold. The key insight that we use is that local tangent spaces in the manifold permit effective combination of both temporal and frequency domain information for more accurate precoder reconstruction. Simulations reveal that we obtain a significant improvement in achievable rate as well as BER reduction when compared to existing strategies.