Uplink reference signal design for GEO dual-polarized MIMO satellite LTE communication system

In this paper, we propose a new uplink reference signal (RS) structure and channel estimation scheme for long term evolution (LTE) compatible geostationary earth orbit (GEO) satellite communication systems over dual-polarized multiple-input multiple-output (MIMO) channels. The conventional discrete Fourier transform (DFT) based least square (LS) channel estimator suffers from a spectral leakage, which results in an irreducible inter-antenna interference in MIMO systems. By exploiting the characteristic of satellite channel, we put forward a joint slot RS structure in both code division multiplexing (CDM) and frequency division multiplexing (FDM) modes, ensuring the orthogonality between antennas, the former of which is compatible with the terrestrial LTE system. In order to further eliminate the influence of noise, a simple implementation of the optimal channel estimator in the linear minimal mean square error (LMMSE) sense in discrete cosine transform (DCT) domain is derived. Finally, the effectiveness of the proposed RS structure and channel estimation method is verified via simulations.