The invention discloses a 4D
tensor-based RIS-assisted
millimeter wave
MIMO-
NOMA Internet of Vehicles
system channel
estimation method, and aims to reduce the influence of serious
Doppler frequency shift and
sight line path blockage on communication performance, first, a 5G
subframe division scheme without changing a standard 5G frame structure is proposed by introducing concepts of aggregation time slot and half time slot, and a 5G
subframe division scheme without changing a standard 5G frame structure is provided; modeling of the received
signal is facilitated; then, modeling the received
signal into a four-order
tensor so as to separate channel parameters into four factor matrixes, thereby avoiding parameter
coupling; then, the
tensor is decomposed in a closed-
form solution form; then, carrying out one-dimensional search on a
factor matrix obtained by
decomposition to extract channel parameters; after channel parameters are obtained, a least square problem is constructed to obtain channel path gains, and solving of a scaling matrix is avoided; finally, experiments verify that the method can accurately estimate the parameters of the channel, and excellent
demodulation performance can be realized based on the parameters of the channel.