| Summary |
In cooperative intelligent transport systems, local dynamic maps (LDMs) are used to achieve safe and efficient transport systems. To transmit LDM data, a reliable, low-latency wireless communication is required. However, the transmission quality between base stations and distant vehicles often degrades, resulting in delays due to retransmission requested by upper-layer protocols. To solve it, in this paper, we propose an uplink cooperative relay transmission scheme using two timeslots in the physical layer, where a vehicle close to a base station relays data from a more distant vehicle. The scheme uses non-orthogonal superposition relaying at the close vehicle and maximum ratio combining at the base station, and improves quality of the data received by the distant vehicle. In addition, high-latency retransmission can be avoided using this scheme. The performance of the proposed scheme is evaluated with link budget calculations and numerical simulations, and it is shown that the proposed scheme greatly enhances a throughput of the distant vehicle. |
