Research On Optimization For Receiver Of Cooperative Ambient Backscatter Communication System

In recent years,with the development of the Internet of Things(IoT)technology,many Internet of Things application scenarios have become true in our life.In the future,the Internet of Things technology will be combined with 5G technology,and more and more smart devices will be connected to the Internet of Things.Most of the existing smart devices have high power consumption and require energy replenishment regularly.In the Ambient Backscatter Communication(AmBC)system,the ambient backscatter devices get energy from the RF signal and modulate their information symbols over the ambient RF signals.The ambient backscatter devices no longer need to be equipped with active RF units,and no additional spectrum is required.Therefore,Am BC has the advantages of low power consumption,low cost and high spectrum utilization.However,when the receiver detects the signal of the ambient backscatter device,the strength of the ambient radio frequency signal is too high,which interferes with the recovery of the ambient backscatter signal.The Cooperative Ambient Backscatter Communication(CABC)system combines the radio frequency communication system and the ambient backscatter system.The receiver adopts cooperative reception in the process of signal detection.Unlike traditional receivers,the cooperative receiver no longer regards the radio frequency signal as interference but recovers the radio frequency signal and the ambient backscatter signal at the same time.CABC realizes stable and efficient ambient backscatter communication.This paper studies the signal detection algorithms of different types of CABC systems,and designs the signal detection algorithms in the Single-Inductor Multiple-Output(SIMO)multi-ambient backscatter device CABC system and the Multiple-Input Multiple-Output(MIMO)multi-ambient backscatter device CABC system.First,this article introduces the signal detection algorithm in the SIMO single ambient backscatter device CABC system.Then we redesign this system to the SIMO multi-ambient backscatter devices CABC system.In this system,the receiver needs to recover the signal of the SIMO system and the signal of multiple ambient backscatter devices at the same time.Due to the change of the system and the signal model,we redesign two kinds of ML detectors,the linear detectors,and the SIC detectors.As the number of access devices increases,the algorithm complexity increases sharply.We designed the Sphere Decording detector,the detector reduces the complexity of the algorithm while ensuring the optimal bit error rate performance.The bit error rate performance of the SIC detector is severely lost.We design the ordered successive interference cancellation detector,the detector effectively solves the error inheritance problem between the different reflection devices and has excellent bit error rate performance.When the radiofrequency system is a MIMO communication system,we designed MIMO multi-ambient backscatter devices CABC system,the receiver needs to recover the signal of the MIMO system and the signal of multiple ambient backscatter devices at the same time.For the new system,this paper optimizes the design of the ML detector,the linear detector and the OSIC detector.In response to the increased complexity of the detector,we designed the low complexity sphere decoding detector and the reduced Z-order low-complexity sphere decoding detector.The Simulation prove that the Lowcomplexity sphere decoding detector reduces the complexity of the detection algorithm while having the optimal bit error rate performance and the Reduced Z-order low-complexity sphere decoding detector has a sub-optimal bit error rate performance.