Abstract
ESP-NOW is a peer-to-peer wireless communication protocol developed by Espressif Systems for low-power and low-cost in-situ Internet of Things devices. ESP-NOW supports bidirectional communication between multiple transmitters (masters) and multiple end-devices (slaves). It also supports both unicast and broadcast transmissions. This paper proposes a synchronized method, called Sync-ESP-NOW, to improve the energy efficiency of the end-devices by scheduling broadcast transmissions in predefined time intervals. The proposed method creates a synchronized application layer which allows the end-devices to be in on mode only when a master's transmission is performed, while they remain in sleep mode to conserve energy for the rest of the time. However, due to the periodic wake-up of the end-devices, a compromise in terms of delay exists. We evaluate the proposed approach through a series of experiments and demonstrate significant improvements in terms of energy efficiency at the end-devices without compromising the packet reception ratio. The proposed approach achieves an up to 96% lower energy consumption considering various packet rate scenarios.