Anti-Jamming Null Space Projection Beamforming Based on Symbiotic Radio

With the development of information technology,more and more devices are connected to the Internet through wireless communication to complete data interconnection.Due to the broadcast characteristics ofwireless channels,wireless networks have suffered more and more malicious attacks.Physical layer security has received extensive attention from industry and academia.MIMO is considered to be one of the most important technologies related to physical layer security.Through beamforming technology,messages can be transmitted to legitimate users in an offset direction that is as orthogonal as possible to the interference channel to ensure the reception SINR by legitimate users.Combining the symbiotic radio(SR)technology,this paper considers a symbiotic radio antijamming MIMO system equipped with a multi-antenna system at the main base station.In order to avoid the interference signal and improve the SINR of the signal received by the user.The base station is equipped with a uniform rectangular antenna array,and using Null Space Projection(NSP)Beamforming,Intelligent Reflecting Surface(IRS)can assist in changing the beam’s angle.The simulation results show that NSP Beamforming could make a better use of the null space of interference,which can effectively improve the received SINR of users under directional interference,and improve the utilization efficiency of signal energy.

Reconfigurable Intelligent Surface-Based Hybrid Phase and Code Modulation for Symbiotic Radio

Reconfigurable intelligent surface(RIS)-assisted symbiotic radio is a spectrum-and energy-efficient communication paradigm,in which an RIS performs passive beamforming to enhance active transmission,while using the electromagnetic waves from the active transmission for additional information transfer(i.e.,passive transmission).In this paper,a hybrid RIS-based modulation,termed hybrid phase and code modulation(HPCM),is proposed to improve the reliability of RIS-assisted symbiotic radio.In RIS-HPCM,the RIS simultaneously performs direct sequence spread spectrum and passive beamforming on incident signals.Moreover,both the spreading code and phase offset are exploited to carry the RIS’s own information.A low-complexity detector is designed,in which the receiver first detects the spreading codes and then demodulates the constellation symbols.We analyze the bit error rate(BER)performance of RIS-HPCM over Rician fading channels.BER upper bounds and approximate BER expressions are derived in closed-form for maximum-likelihood and low-complexity detectors,respectively.Simulation results in terms of BER verify the analysis and show the superiority of RIS-HPCM over the existing RIS-based modulation.

Intelligent Reflecting Surface with Power Splitting Aided Symbiotic Radio Networks

The performance of symbiotic radio(SR)networks can be improved by equipping secondary transmitters(STs)with intelligent reflecting surfaces(IRSs).Since the IRS power consumption is a non-negligible issue for STs,we consider an IRS assisted SR system where the IRS operates under power splitting(PS)mode.We aim at minimizing the IRS power consumption for the ST under the quality of service constraints for both primary and secondary transmissions by optimizing the transmit beamforming,the reflect beamforming and the PS factor.The optimization problem is non-convex.To tackle it,an algorithm is proposed by employing the block coordinate descent,semidefinite relaxation and alternating direction method of multipliers techniques.Simulation results demonstrate the efficiency and effectiveness of the proposed algorithm.

Symbiotic Radio Systems:Detection and Performance Analysis

Symbiotic radio(SR)is an emerging green technology for the Internet of Things(IoT).One key challenge of the SR systems is to design efficient and low-complexity detectors,which is the focus of this paper.We first drive the mathematical expression of the optimal maximum-likelihood(ML)detector,and then propose a suboptimal iterative detector with low complexity.Finally,we show through numerical results that our proposed detector can obtain near-optimal bit error rate(BER)performance at a low computational cost.

Carrier Frequency Offset Estimation for FM and Symbiotic FM Radio Data System Hybrid Signal

The symbiotic FM radio data system(SRDS)is a radio data system that a specially designed OFDM signal co-lives with FM signal,which enables a significantly higher data rate than existing radio data systems.The cyclic prefix of the OFDM symbol has the same length as the OFDM body,which enables the analytic separation of the co-channel OFDM and FM signal at receiver side,utilizing the fact that the OFDM body and prefix is equal.In this work,we show that the OFDM body and prefix cannot be viewed as equal when there is sufficient carrier frequency offset(CFO).Thus,we propose a two-step CFO estimation algorithm for FM and SRDS hybrid signal.The first step estimates the coarse CFO by exploring the characteristics of the FM signal.Once the coarse CFO is removed,the residual CFO is small enough for FM and OFDM separation.The second step fine estimates CFO from the OFDM-only signal using its repeated PN structure after the separation.Detailed mathematical equations are formulated and simulation results are given.The results show that the proposed algorithm works fine with the simulation setup and has a final residual CFO less than 3.9Hz.

Large Intelligent Surface/Antennas (LISA): Making Reflective Radios Smart

Large intelligent surface/antennas(LISA),a two-dimensional artificial structure with a large number of reflective-surface/antenna elements,is a promising reflective radio technology to construct programmable wireless environments in a smart way.Specifically,each element of the LISA adjusts the reflection of the incident electromagnetic waves with unnatural properties,such as negative refraction,perfect absorption,and anomalous reflection,thus the wireless environments can be software-defined according to various design objectives.In this paper,we introduce the reflective radio basics,including backscattering principles,backscatter communication,reflective relay,the fundamentals and implementations of LISA technology.Then,we present an overview of the state-of-the-art research on emerging applications of LISA-aided wireless networks.Finally,the limitations,challenges,and open issues associated with LISA for future wireless applications are discussed.