MIMO–OFDM communication systems for traffic data transmission in 5G drone small cells

A compressed sensing‐based channel estimation (CE) method is proposed for doubly selective channels whilst multiple‐input multiple‐output (MIMO)–orthogonal frequency‐division multiplexing (OFDM) system is employed. According to the simulation results, the proposed CE method, which is dubbed as the MIMO‐linearising scheme performs better than the basic expansion model (BEM), which is a state‐of‐the‐art CE method and applies frequency domain scattered pilots. Furthermore, MIMO‐linearising can be utilised as an accurate procedure for estimating only the positions of non‐zero channel taps in the scenarios where those positions change with a slower rate than amplitudes and phases of the channel taps. Based on that priori estimated positions (PEPs), modified versions of the linearising scheme and the BEM methods, called MIMO‐linearising‐PEP and BEM‐PEP, respectively, are described, showing improvement on performance and spectral efficiency. In addition, by considering the physical characteristic of the vehicular channels, an alternative version of the MIMO‐linearising‐PEP, called MIMO‐linearising‐efficient, is described to reduce the computational complexity and increase the spectral efficiency further. Simulation results indicate that the proposed CE methods can measure the channel more accurately and enhance the car detection accuracy in the frames which have been used as the inputs of the communication systems.