  This paper proposes to leverage intelligent reflecting surface (IRS)
backscatter to realize radio-frequency-chain-free uplink-transmissions
(RFCF-UT). In this communication paradigm, IRS works as an information carrier,
whose elements are capable of adjusting their amplitudes and phases to
collaboratively portray an electromagnetic image like a dynamic quick response
(QR) code, rather than a familiar reflection device, while a full-duplex base
station (BS) is used as a scanner to collect and recognize the information on
IRS. To elaborate it, an integrated sensing, communication and computation
system as an example is presented, in which a dual-functional
radar-communication BS simultaneously detects the target and collects the data
from user equipments each connected to an IRS. Based on the established model,
partial and binary data offloading strategies are respectively considered. By
defining a performance metric named weighted throughput capacity (WTC), two
maximization problems of WTC are formulated. According to the coupling degree
of optimization variables in the objective function and the constraints, each
optimization problem is firstly decomposed into two subproblems. Then, the
methods of linear programming, fractional programming, integer programming and
alternative optimization are developed to solve the subproblems. The simulation
results demonstrate the achievable WTC of the considered system, thereby
validating RFCF-UT.
