Spectrum Hand-Off for RF Energy Harvesting in Cognitive Radio Based Machine to Machine Communication Networks

It is critical for a machine equipped with the battery of limited energy to transmit data with shorter delay in machine type communication networks because the machine in an energy-insufficient state does not send data immediately. Although a machine can equip the capability of radio frequency (RF) energy harvesting, there is a trade-off between RF energy-harvesting rate and the opportunity to send data in a radio band. Therefore, we propose a spectrum hand-off for energy harvesting in cognitive radio based machine type communication networks. Using the proposed spectrum hand-off, a machine can determine (i) the appropriate time that a machine harvests RF energy from which radio band and (ii) the time to send data or sleep such that more energy is gathered from two radio bands and then more data is sent in shorter waiting time. Simulation results show that the proposed spectrum hand-off can yield lower mean packet request delay in light and middle load and increase utilization of time slots (or throughput).