Uplink enhancement of vehicular users by using D2D communications

In this paper, we discuss one application enabled by device-to-device (D2D) communication for vehicular users inside well isolated public transportation vehicles. We study the feasibility of using D2D communication to enhance the uplink communication for vehicular user equipment (VUE) devices. D2D communication allows fast data exchange among VUE devices, and therefore, a number of VUE devices can cooperate with each other and send data to the base station (BS) together. We employ a generalized co-phasing technique for the cooperation with perterminal power constraint, and compare the energy efficiency of single user direct transmission, and cooperative transmission participated by various number of VUE devices. As the public transportation vehicle moves away from the BS and for large vehicular penetration loss, less energy is required to send the same amount of data of each active VUE in the cooperative transmission than the individual VUE-to-BS communications. Hence VUE devices in well isolated vehicles, especially those ones with limited battery lives, can save energy because of the enhanced uplink communications.