Unsupervised Learning for Pilot-free Transmission in 3GPP MIMO Systems
This addresses spectral efficiency improvement for 3GPP MIMO systems, representing an incremental advance in pilot reduction techniques.
The paper tackles the problem of reference signal overhead in 3GPP MIMO systems by introducing a pilot-free transmission structure that repeats user data across sub-bands, enabling reliable recovery via canonical correlation analysis without channel estimation, and numerical results show superiority over state-of-the-art methods.
Reference signals overhead reduction has recently evolved as an effective solution for improving the system spectral efficiency. This paper introduces a new downlink data structure that is free from demodulation reference signals (DM-RS), and hence does not require any channel estimation at the receiver. The new proposed data transmission structure involves a simple repetition step of part of the user data across the different sub-bands. Exploiting the repetition structure at the user side, it is shown that reliable recovery is possible via canonical correlation analysis. This paper also proposes two effective mechanisms for boosting the CCA performance in OFDM systems; one for repetition pattern selection and another to deal with the severe frequency selectivity issues. The proposed approach exhibits favorable complexity-performance tradeoff, rendering it appealing for practical implementation. Numerical results, using a 3GPP link-level testbench, demonstrate the superiority of the proposed approach relative to the state-of-the-art methods.