Latency and Task Loss Probability for NOMA Assisted MEC in Mobility-Aware Vehicular Networks

In vehicular networks, task offloading performance for mobile edge computing (MEC) is highly coupled with the mobility of vehicle terminal (VT), as the VT speed and arrival rate determine the number of VTs and their sojourn time on each road segment. Generally, the communication and computation resources of the MEC server are limited, and thus more VTs leads to less resources for each VT. In this paper, we develop an analytical non-orthogonal multiple access (NOMA) assisted MEC model to characterize VT mobility and analyze the impact of VT mobility on task offloading performance. In this model, each VT with random speed starts its offloading at any time and hopefully completes the task offloading before leaving the current road segment. The expressions of average latency and task loss probability are derived and validated by simulation results. Furthermore, the impact of VT mobility, especially the average VT speed, on latency performances is analyzed. It is also shown that task loss probability is mainly affected by VT arrival rate, and is approximately independent of average VT speed.