Grant-Free Data-only Transmission with Correlated Antenna Array.

Grant-free data-only transmission, as one type of contention-based grant-free transmission, has great potential to satisfy the requirements of low latency and massive connections for emerging use cases. The data-only transmission with multiple independent antennas has been considered in existing work, while in this paper the data-only transmission with correlated antenna array is discussed, where blind receive beamforming is performed on multi-antenna receiving signals, and the precoding codebooks for downlink MIMO transmission in 5G New Radio system are used as the uplink spatial combining vectors. Furthermore, vector identification can be conducted to reduce the receiver complexity, and an iterative vector combination and identification method is provided to obtain more suitable spatial combining vectors for multi-path fading channel scenario, simulation results show that with this method the performances are significantly improved.