Cooperative NOMA Heterogeneous V2X Network in THz Band

Terahertz (THz) communications is envisioned as one of the promising candidates for future vehicular networks. Introducing this new band in vehicle-to-everything communication (V2X) is indispensable to support ultra-high data rates with massive bandwidth. Achieving higher spectrum utilization and alleviating the resource conflicts such as limited transmission capacity and unpredictable propagation delays in V2X communications can be realized using non-orthogonal multiple access (NOMA). In this paper, we integrate the benefits of NOMA and THz in a downlink heterogeneous V2X network. We maximize the data rate for the vehicle user equipment (VUE) by deriving a closed-form expression to obtain the optimal power allocation. The minimum requirement for the cellular user equipment (CUE) has been satisfied throughout the analysis and the effect of using different power allocation factors is showed. In addition, a cooperative receive diversity is accommodated in our model to enhance the reliability. The results show the enhancement in data rates for optimal NOMA power allocation factors compared to equal power allocation and the effect of VUE location on the data rate.