International Conference on Emerging Technologies for Communications
Adaptive MIMO mode-switching scheme for flexible 5G URLLC transmission
Yusaku Shiomitsu, Eiji Okamoto, Manabu Mikami, Hitoshi Yoshino,
Ultra-reliable and low-latency communication (URLLC) is one of the main use cases of the fifth-generation mobile communications system (5G), which has been developed to achieve autonomous driving and other applications. To achieve URLLC, wireless transmission technologies that satisfy both reliability and low latency are required. Currently, in the automotive and industrial Internet of things, some use cases with high payloads are envisioned for URLLCs, and the demand for higher throughput is expected to increase. Therefore, a new technique is proposed for improving the reliability and throughput performances of 5G URLLC in a line-of-sight environment by utilizing dual-polarized multiple-input multiple-output (MIMO) transmission with adaptive multiplexing and diversity. Conventional URLLC methods use a retransmission of negative-acknowledged packets in the time axis. However, the URLLC latency requirement limits the maximum number of retransmissions. Therefore, the retransmission packets are placed in the spatial axis. Then, it is possible to increase the maximum number of retransmissions by using the time and spatial axes while satisfying the low-latency requirement. Meanwhile, when the channel environment is good, one can increase the throughput by adaptively utilizing a MIMO multiplexing transmission in the spatial axis, that is, different packets are simultaneously transmitted. Numerical simulations demonstrate that the proposed method achieves the same reliability and throughput, while maintaining a delay time below 1 ms, as the fixed polarized multiplexing MIMO with a delay time of 2 ms. The proposed method is also demonstrated to be more reliable than the ideal performance of conventional fixed polarized MIMO multiplexing transmission with an ideal adaptive modulation and coding scheme.