Combined electrical transport and capacitance spectroscopy of a MoS2−LiNbO3{\mathrm{MoS_2-LiNbO_3}} field effect transistor

We have measured both the current-voltage ($I_\mathrm{SD}$-$V_\mathrm{GS}$) and capacitance-voltage ($C$-$V_\mathrm{GS}$) characteristics of a $\mathrm{MoS_2-LiNbO_3}$ field effect transistor. From the measured capacitance we calculate the electron surface density and show that its gate voltage dependence follows the theoretical prediction resulting from the two-dimensional free electron model. This model allows us to fit the measured $I_\mathrm{SD}$-$V_\mathrm{GS}$ characteristics over the \emph{entire range} of $V_\mathrm{GS}$. Combining this experimental result with the measured current-voltage characteristics, we determine the field effect mobility as a function of gate voltage. We show that for our device this improved combined approach yields significantly smaller values (more than a factor of 4) of the electron mobility than the conventional analysis of the current-voltage characteristics only.Comment: to appear in Applied Physics Letter

Intelligent OFDM Telecommunication Systems Based on Many-Parameter Complex or Quaternion Fourier Transforms

In this paper, we propose novel Intelligent quaternion OFDM-telecommunication systems based on many-parameter complex and quaternion transform (MPFT). The new systems use inverse MPFT (IMPFT) for modulation at the transmitter and direct MPFT (DMPFT) for demodulation at the receiver. The purpose of employing the MPFT is to improve: (1) the PHY-LS of wireless transmissions against to the wide-band anti-jamming and anti-eavesdropping communication; (2) the bit error rate (BER) performance with respect to the conventional OFDM-TCS; (3) the peak to average power ratio (PAPR). Each MPFT depends on finite set of independent parameters (angles). When parameters are changed, many-parametric transform is also changed taking form of different quaternion orthogonal transforms. For this reason, the concrete values of parameters are specific “key” for entry into OFDM-TCS. Vector of parameters belong to multi-dimension torus space. Scanning of this space for find out the “key” (the concrete values of parameters) is hard problem. © 2020, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.Russian Foundation for Basic Researc

Many-Parameter Quaternion Fourier Transforms for Intelligent OFDM Telecommunication System

In this paper, we aim to investigate the superiority and practicability of many-parameter quaternion Fourier transforms (MPQFT) from the physical layer security (PHY-LS) perspective. We propose novel Intelligent OFDM-telecommunication system (Intelligent-OFDM-TCS), based on MPFT. New system uses inverse MPQFT for modulation at the transmitter and direct MPQFT for demodulation at the receiver. The purpose of employing the MPFTs is to improve the PHY-LS of wireless transmissions against to the wide-band anti-jamming communication. Each MPQFT depends on finite set of independent parameters (angles), which could be changed independently one from another. When parameters are changed, multi-parametric transform is also changed taking form of a set known (and unknown) orthogonal (or unitary) transforms. We implement the following performances as bit error rate (BER), symbol error rate (SER), the Shannon-Wyner secrecy capacity (SWSC) for novel Intelligent-MPWT-OFDM-TCS. Simulation results show that the proposed Intelligent OFDM-TCS have better performances than the conventional OFDM system based on DFT against eavesdropping. © 2020, The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.Russian Foundation for Basic Researc

5GNOW: Intermediate frame structure and transceiver concepts

This paper reports intermediate transceiver and frame structure concepts and corresponding results from the European FP7 research project 5GNOW. The core is the unified frame structure concept which supports an integrated 5G air interface, capable of dealing both with broadband data services and small packet services within the same band. It is essential for this concept to introduce waveforms which are more robust than OFDM, e.g., with respect to time-frequency misalignment. Encouraging candidate waveform technologies are presented and discussed with respective results. This goes along with the corresponding multiple access technologies using multi-layered signals and advanced multi-user receivers. In addition we introduce new (compressive) random access strategies to enable 'one shot transmission' with greatly reduced control signaling particularly for sporadic traffic by orders of magnitude. Finally, we comment on the recent results on the 5GNOW networking interface. The intermediate results of 5GNOW lay the ground for the standardization path towards a new 5G air interface beyond LTE-A