Power allocation based on finite-horizon optimization for vehicle-to-roadside communications

In this paper, we study the power allocation strategy in a drive-thru scenario, where an access point (AP) is installed along the highway to provide Internet services to vehicles within its coverage range. We consider single-hop vehicle-to-roadside (V2R) communications for a vehicle that aims to upload data within the coverage range of the AP, where the bandwidth allocated to it is time-varying, and the size of the data is known upon it enters the area. The data bits received over a time slot are correctly received if the instantaneous channel capacity r_t is greater than or equal to a threshold R_t, and corrupted otherwise. The vehicle has to pay an amount for data transmission according to the power consumption at each time slot whether the data bits are correctly received or not. The target is to complete the transmission of the traffic demand volume with the minimal cost. First, we consider the optimal power allocation strategy with a single AP and random vehicular traffic arrivals. We formulate it as a finite-horizon sequential power allocation problem. Then we solve the problem using dynamic programming and find the optimal power allocation strategy. The proof of the existing of the optimal value of the cost-to-go function is given after. Simulation results show that our proposed strategy achieves less cost than another heuristic strategy. The impacts of different traffic demand volumes, traffic densities, and outage probabilities on total cost are also analyzed.