This invention introduces an energy-efficient communication protocol for Ambient IoT, integrating Slotted
ALOHA with
RF energy harvesting to enable reliable interaction between ultra-low-power, battery-less devices and 5G / 6G base stations or
relay UEs. Devices first harvest energy from a Carrier Wave (CW)
signal, followed by a structured five-message exchange (Msg0–Msg4) handling synchronization,
random access,
data transmission, and acknowledgments. Time-frequency resources are dynamically allocated based on device energy levels and random IDs, reducing collisions and improving
throughput. Control signals use differential encoding for robustness. Each message is framed with a
preamble and postamble, allowing the device to detect the start and end of the
signal. Padding is inserted before the
preamble to ensure alignment with NR OFDM symbol boundaries. A Slotted
ALOHA-based
retransmission strategy enhances
channel reuse. Eliminating dedicated RFID readers, this approach supports long-range, interference-managed communication, offering a scalable, low-latency, and cost-
effective solution for massive
machine-type communication (mMTC) in next-generation Ambient IoT networks.