Transmission Scheduling for Hybrid Backscatter-HTT Nodes

We consider a system with one single-antenna reader and multiple hybrid backscatter-harvest-then-transmit (HTT) transmitters. The transmitters can operate in either the backscattering mode or the HTT mode; and the reader that supports both operating modes acts as a power transmitter and information receiver. The objective is to determine the transmission mode of all transmitters and minimize the total transmission time of the system. We provide problem formulations under both ideal and realistic power consumption models for HTT transmitters. We theoretically prove several key properties of the system under both models and develop bisection-based algorithms to solve the problems optimally with complexity <inline-formula> <tex-math notation="LaTeX">$\mathcal {O}(\log K)$ </tex-math></inline-formula> where <inline-formula> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> is the number of transmitters. The results are then further extended to the case of a massive MIMO reader.