The size of the uplink and downlink frames depends on the size of the input image and the number of detected objects in the image, respectively. Based on our preliminary experiments, we found that the size of the downlink frame is relatively small (i.e., M UL i M DL i ) than that of the uplink frame, indicating that the last term in (3) is negligible. In addition, d q,i can be treated as a constant based on the assumption that the object detection workloads are static and the edge server always operates at maximum performance. Therefore, the offloading delay D OFF i at the ith mobile edge device depends on the uplink **data** rates r U L i and the queueing delay d q,i incurred at the remote edge server. The queueing delay d q,i in (3) is obtained by the number of offloading requests stored in the queue of the edge server and the remaining time for the ongoing offloading service, which are unknown in advance. It implies that the queueing delay can be treated as a random variable with bounded support, that is, 0 ≤ d q,i ≤ (N OFF − 1)d OFF p , in which N OFF is the number of mobile edge devices offloading object detection workloads.