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Bit error rates of QPSK, 8PSK, and 16QAM modulation with different transmitting powers through the TDCM based wireless communication system. (a) BERs comparison of three kinds of modulation schemes at two different symbol rates. The BERs measurement results of QPSK, 8PSK and 16QAM modulation are respectively shown in (b-d).
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Metasurfaces are well-designed artificial periodic or quasi-periodic structures to achieve customized electromagnetic responses. Based on the time-domain digital coding metasurface (TDCM) with dynamic reflection or transmission characteristics, one can realize direct information modulation on the metasurface, which has been used in wireless communi...
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Citations
... It can be used to construct wireless relays [13,14], actively modulate the wireless channel environment, enhance signal coverage strength, and improve the transmission rate of the communication system. Additionally, it can be used to construct new wireless communication transmitters [15][16][17][18]. By controlling the array unit's reflective phase, amplitude, frequency, or polarization characteristics, the feed-incident carrier signal can be modulated directly, without the need for an analogdigital/analog-digital converter, a modulator, and other components, thus greatly reducing the hardware complexity, energy consumption, and manufacturing cost. ...
In this paper, a 3-bit circularly polarized reconfigurable reflectarray is proposed. The array consists of 64 units in an 8 × 8 configuration, with each unit containing a circular metal patch loaded with phase-delay lines and eight PIN diodes. To independently control each unit, a corresponding DC control circuit was designed and tested with the array. In the bandwidth of 3.43–3.71 GHz, the circularly polarized reconfigurable reflectarray achieved a gain of 16 dB, an aperture efficiency of 27%, an axial ratio of ≤3 dB, an operating bandwidth of 8%, and a beam scanning range of ±60°. The circularly polarized reconfigurable reflectarray can also achieve a good dual-beam radiation performance after testing. The 3-bit circularly polarized reconfigurable reflectarray proposed in this paper offers several advantages, including low loss, high aperture efficiency, a wide beam scanning range, and excellent stability in wide-angle oblique incidence. It has potential applications in low-cost phased array, satellite communications, and deep space exploration.
... STCM, also named time-domain digital coding metasurface [12], is a class of low-cost non-linear metasurfaces that manipulate electromagnetic waves in both space and frequency domains. It can be viewed as a RIS topology that exploits not only space scattering [11], i.e. fixing the coding sequences in time, but also multiple frequencies spread in the space. ...
Intelligent metasurfaces are one of the favorite technologies for integrating sixth-generation (6G) networks, especially the reconfigurable intelligent surface (RIS) that has been extensively researched in various applications. In this context, a feature that deserves further exploration is the frequency scattering occurs when the elements are periodically switched, referred to as Space-Time-Coding metasurface (STCM) topology. This type of topology causes impairments to the established communication methods by generating undesirable interference both in frequency and space, which is worsened when using wide-band signals. Nevertheless, it has the potential to bring forward useful features for sensing and localization. This work exploits STCM sensing capabilities in target detection, localization, and classification using narrowband downlink pilot signals at the base station (BS). The results of this novel approach reveal the ability to retrieve a scattering point (SP) localization within the sub-centimeter and sub-decimeter accuracy depending on the SP position in space. We also analyze the associated detection and classification probabilities, which show reliable detection performance in the whole analyzed environment. In contrast, the classification is bounded by physical constraints, and we conclude that this method presents a promising approach for future integrated sensing and communications (ISAC) protocols by providing a tool to perform sensing and localization services using legacy communication signals.
... Other BF Approaches [15,17] This Work purpose of the work security security [14] low-cost modulator [16] security low-cost modulator with security requiring modulated signal no [11,18] yes [12] no [16] yes [14] yes no multi-user support no no no yes amplitudes and phases of transmitted signals in specific directions by the means of beamformer weights. Its roots extend to 1990 [8] where the first directional binary phase-shift-keying (BPSK) was proposed by switching the transmitter antenna. ...
... Other BF Approaches [15,17] This Work purpose of the work security security [14] low-cost modulator [16] security low-cost modulator with security requiring modulated signal no [11,18] yes [12] no [16] yes [14] yes no multi-user support no no no yes amplitudes and phases of transmitted signals in specific directions by the means of beamformer weights. Its roots extend to 1990 [8] where the first directional binary phase-shift-keying (BPSK) was proposed by switching the transmitter antenna. ...
... Improvements in secrecy rate and signal-to-interference-plus-noise ratio (SINR) were achieved with closed form expressions. Another RIS-assisted DM system was presented in [16], where the signal is modulated in the RIS directly by the proposed time-domain digital coding approach. A detailed comparison of existing literature is listed in Table 1. ...
Large intelligent surfaces arise as an emerging technology and critical building block for sixth generation (6G) wireless networks. Reconfigurable holographic surfaces (RHSs) have been attracting significant attention recently as active antenna arrays with the capability of forming narrow beams at low cost and complexity. This paper introduces the directional modulation (DM) concept for RHS, where a large number of elements is exploited to control not only the signal's power at the receiver but also its phase. Thus, a novel DM algorithm is proposed for RHS enables modulating a carrier wave to transmit information towards specific directions while broadcasting arbitrary signals towards other directions. Error vector magnitude (EVM) results are reported for multiple users, where the directions of two users with respect to the RHS are varied. Mutual information result is also provided for 6 users to demonstrate the application of RHS for the physical layer security. Results are highly promising for future low-cost and secure spatially multiplexed communications.
... characteristics in each period for STCM offers the possibility of generating multiple harmonics at the same time with high nonlinear conversion efficiencies [32][33][34] . Moreover, the strategy for joint amplitude and phase modulations of the nonlinear harmonics has been presented to realize precise wave manipulations at different harmonic frequencies, thereby giving rise to multiple wireless channels for information transmissions 23,[35][36][37][38][39][40] . In general, the continuous reflection phase is discretized into finite phase states with the phase step of 2π⁄2 n , where n is the quantization bit number. ...
Manipulations of multiple carrier frequencies are especially important in a variety of fields like radar detection and wireless communications. In conventional radio-frequency architecture, the multi-frequency control is implemented by microwave circuits, which are hard to integrate with antenna apertures, thus bringing the problems of expensive system and high power consumption. Previous studies demonstrate the possibility to jointly control the multiple harmonics using space-time-coding digital metasurface, but suffer from the drawback of inherent harmonic entanglement. To overcome the difficulties, we propose a multi-partition asynchronous space-time-coding digital metasurface (ASTCM) to generate and manipulate multiple frequencies with more flexibility. We further establish an ASTCM-based transmitter to realize wireless communications with frequency-division multiplexing, where the metasurface is responsible for carrier-wave generations and signal modulations. The direct multi-frequency controls with ASTCM provides a new avenue to simplify the traditional wireless systems with reduced costs and low power consumption.
... In recent years, spatiotemporally modulated metasurfaces have become an emerging technique to engineer EM waves in both space and time. Spatiotemporally modulated metasurfaces have introduced an additional dimension, time, into the conventional metasurface design, enabling intriguing physical phenomena [36][37][38][39][40][41] and wave manipulations in frequency-momentum spaces [42][43][44][45][46][47][48][49][50] . In particular, the waveguide-integrated metasurface antenna allows high-efficiency frequency controls without sideband pollution 44,51,52 . ...
Metasurfaces have promising potential to revolutionize a variety of photonic and electronic device technologies. However, metasurfaces that can simultaneously and independently control all electromagnetics (EM) waves’ properties, including amplitude, phase, frequency, polarization, and momentum, with high integrability and programmability, are challenging and have not been successfully attempted. Here, we propose and demonstrate a microwave universal metasurface antenna (UMA) capable of dynamically, simultaneously, independently, and precisely manipulating all the constitutive properties of EM waves in a software-defined manner. Our UMA further facilitates the spatial- and time-varying wave properties, leading to more complicated waveform generation, beamforming, and direct information manipulations. In particular, the UMA can directly generate the modulated waveforms carrying digital information that can fundamentally simplify the architecture of information transmitter systems. The proposed UMA with unparalleled EM wave and information manipulation capabilities will spark a surge of applications from next-generation wireless systems, cognitive sensing, and imaging to quantum optics and quantum information science.
... Nonlinear signal modulation: Metamaterials and metasurfaces employed for nonlinear modulation schemes, offering advantages in spectral efficiency, signalto-noise ratio, and interference resistance (Dai et al., 2020). ...
... /j.mee.2015 Dai, J. Y.,Tang, W., Yang, L. X., Li, X., Chen, M. Z., Ke, J. C., Cheng, Q., Jin, S., & Cui, T. J. (2020). Realization of Multi-Modulation Schemes for Wireless Communication by Time-Domain Digital Coding Metasurface. ...
Metamaterials and metasurfaces are enabling modern 5G/6G wireless systems to achieve high performance while maintaining efficient costs and sizes. In the wireless industry, transmission lines play a fundamental role in the development of guided wave elements, antennas, radio frequency identification (RFID) tags, and sensors whose efficiency may be enhanced using metamaterials. Additionally, a metamaterial absorber can solve the bandwidth issue of the internet of things (IoTs) backhaul network. Metasurfaces are also potential candidates for implementing reconfigurable intelligent surfaces (RISs) due to their special wireless communication capabilities. Metamaterial Technology and Intelligent Metasurfaces for Wireless Communication Systems compiles and promotes metamaterials research and sheds light on how metamaterials and metasurfaces will be used in the 5G era and beyond. Covering topics such as active and passive metamaterials, metasurfaces-inspired antennas, and metamaterials for RFID and sensors, this book is ideal for researchers, students, academicians, and professionals.
... Metasurfaces are 2-D arrangements of engineered scatters on a subwavelength scale, which have gained increasing attention in recent years due to their strong capabilities of controlling the electromagnetic (EM) waves with low loss, ultrathin thickness, and easy integration [14], [15], [16], [17], [18], [19]. In addition, they can be easily integrated with the new-generation transparent conductive material [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], among which metal mesh, especially Ag metal mesh (AMM) [20], [21], [22], has attracted continuous attention due to its good photoelectric performance. ...
High transmission of electromagnetic (EM) waves is closely related to the reliability and stability of the indoor-to-outdoor wireless communication system. Due to the serious EM attenuation of the normal glasses under large incident angles, transparent film coatings that can be attached to the glasses have attracted extensive attention to maintain high EM transmissions in a wide angle range. In this paper, a wideband and wide-angle single-layered transparent metasurface is proposed to enhance the EM transmissions through the glasses. Detailed mechanisms, analytical models and elaborate numerical results are presented. As a proof-of-concept, a prototype of the metasurface based on Ag metal mesh is fabricated and tested. The measured results are in good agreement with the numerical simulations and calculations, thus validating the excellent EM performance. It is expected that the proposed single-layered metasurface with high transmittance in both microwave and light bands can find potential applications in the 5G and 6G communication scenarios.
... Nonlinear signal modulation: Metamaterials and metasurfaces employed for nonlinear modulation schemes, offering advantages in spectral efficiency, signalto-noise ratio, and interference resistance (Dai et al., 2020). ...
... /j.mee.2015 Dai, J. Y.,Tang, W., Yang, L. X., Li, X., Chen, M. Z., Ke, J. C., Cheng, Q., Jin, S., & Cui, T. J. (2020). Realization of Multi-Modulation Schemes for Wireless Communication by Time-Domain Digital Coding Metasurface. ...
In this chapter, the authors introduce the concept of MMA through reviewing the development of conventional absorbers. To illustrate the important operating mechanism, design process, and functionalization of the metamaterial absorber, they show the absorption relation of the absorber, impedance matching condition, equivalent circuit model, the evaluation of thickness, and oblique incidence condition in the first part. Then, they show the basic design method of the absorber, including parameter sweep method, equivalent circuit method, and deep learning method. Next, the planar integration strategy, vertical stacking strategy, and dispersive material strategy for broadband absorption bandwidth are discussed. In addition, they illustrate the tunable design of absorber, involving lumped element design method, thermal tunable design method, electrical tunable design method, mechanical tunable method, and reconfigurable tunable method. Finally, they talk about the basic engineering application of the metamaterial absorber in practical engineering application.
... The idea was validated by using a demonstrator capable of establishing a 20 Mbps communication link. The authors of [13] discuss the realization of advanced modulation schemes by engineering the phase response of the single STMM element. In this direction, the work [14] analyzes the capacity of a RISaided link, where information data are jointly encoded at the transmitter and at the RIS. ...
Space-time modulated metasurfaces (STMMs) are a recently proposed generalization of reconfigurable intelligent surfaces, which include a proper time-varying phase at the metasurface elements, enabling higher flexibility and control of the reflected signals. The spatial component can be designed to control the direction of reflection, while the temporal one can be adjusted to change the frequency of the reflected signal or to convey information. However, the coupling between the spatial and temporal phases at the STMM can adversely affect its performance. Therefore, this paper analyzes the system parameters that affect the space-time coupling. Furthermore, two methods for space-time decoupling are investigated. Numerical results highlight the effectiveness of the proposed decoupling methods and reveal that the space-time phase coupling increases with the bandwidth of the temporal phase, the size of the STMM, and with grazing angles of incidence onto the STMM.
... So far, many efforts have been devoted to implementing metasurfacebased wireless communication systems by directly encoding the digital information onto EM waves. For example, modulation schemes of binary frequency-shift keying (BFSK), quadrate phase-shift keying (QPSK) and quadrate amplitude modulation (QAM) have been demonstrated by modifying the EM properties of the metasurfaces through altering the duty ratios and time delays of the time-varying modulation signals in square waveforms [26,27]. Despite these significant progresses, most of them only encode the transmitted information in the time domain, leaving spacedomain resources unexploited to enable practical functions, for example, dynamic communication service coverage for multi-users or moving users; moreover, the operation bandwidth may be further improved as the large channel capacities are increasingly demanded in the next-generation communications [28]. ...
Reconfigurable metasurfaces have emerged as a promising alternative to the conventional transmitter of wireless communication systems, due to their abilities of encoding digital information onto electromagnetic properties without complex radio-frequency chains. However, most of them are still limited to narrow operation bandwidth. Here, we propose a broadband metasurface-based wireless communication system that can actively adapt to multiple users located at versatile directions through joint modulation of digital signals in the time domain and wave scatterings in the space domain. As exemplary demonstrations, highly directive beams are generated to enhance regional signals in real-time customized for users in desired directions and reduce the signal leakage in undesired directions. Experiments are carried out to verify that the system can provide stable wireless communication service in a broad band of 3.7–5.1 GHz, within which the transmitted color picture enabled by the time-varying spatial modulation of metasurface can be successfully recovered at the user terminals. The proposed system may offer untapped potentials for next-generation communications and radar systems where regional signal enhancement, active adaption to users, and large channel capacities are required.
