Effects of the adjacent channels on IP3 and IP5 of RF amplifier

This paper discusses the impact of the adjacent channels on the 1-dB compression point, the IP3 and the IP5 of Radio Frequency (RF) amplifier by n-tone test. By combining the theoretical derivation and software simulation, the model analysis for the third/five order polynomial nonlinear amplifier has been achieved. Moreover, the control variable method is adopted to draw the curves for the input/output signals. The research shows that the 1-dB compression point, the IP3 and the IP5 drop as n increases, and they all have symmetry for a given n. The fifth-order polynomial nonlinear amplifier model is proposed, the research shows that the adjacent channels have a great impact on the 1-dB compression point, the IP3 and the IP5 of the desired channel. This effect must be taken into account in actual RF amplifier designs and wireless communication architectures.

The Statistical Correlation between Distortion and Adding Signal for PAPR Reduction in OFDM based Communication Systems

In recent past years, PAPR (Peak-to-Average Power Ratio) of OFDM (Orthogonal FrequencyDivision Multiplexing) system has been intensively investigated. Published works mainly focus on how to reduce PAPR. Since high PAPR will lead to clipping of the signal when passed through a nonlinear amplifier. This paper proposes to extend the work related to "Gaussian Tone Reservation Clipping and Filtering for PAPR Mitigation" which has been previously published. So, in this paper, we deeply investigate the statistical correlation between PAPR reduction, and the distortion generated by three (3) adding signal techniques for PAPR reduction. Thereby, we first propose a generic function for PAPR reduction. Then, we analyse the PAPR reduction capabilities of each PAPR reduction technique versus the distortion generated. The signal-to-noise-and-distortion ratio (SNDR) metric is used to evaluate the distortion generated within each technique by assuming that OFDM baseband signals are modelled by complex Gaussian processes with Rayleigh envelope distribution for a large number of subcarriers. The results related to one of the techniques is proposed in the first time in this paper, unlike those related to the other two PAPR reduction techniques where the studies were already published. Comparisons of the proposed approximations of SNDR with those obtained by computer simulations show good agreement. An interesting result highlighted in this paper is the strong correlation existing between PAPR reduction performance and distortion signal power. Indeed, the results show that PAPR reduction gain increases as the distortion signal power increases. Through these 3 examples of PAPR reduction techniques; we could derive the following conclusion: in an adding signal context, the adding signal for PAPR reduction is closely linked to the distortion generated, and a trade-off between PAPR-reduction and distortion must be definitely found.

Simulation model of the transmission path for 5G NR base station

The article presents the results of modeling an analog radio path of a fifth-generation cellular base station in the NI AWR Design Environment. The validation of the power amplifier model was performed in the AWR software environment. The validation is based on the comparison of measurement results for the nonlinear parameters of the amplitude characteristics of the microwave amplifier obtained on the amplifier model, with the results obtained during mathematical modeling of the nonlinear amplifier. The results of measuring the vector magnitude error between the input and output signals in the radiopath model are presented.

Modeling of Amplitude Characteristic in Radio Channels of Code Division Multiple Access Systems

In CDMA radio access systems, amplitude distortions in a nonlinear amplifier (NA) of a group signal lead to bit errors at the outputs of subscriber channels. To assess the permissible distortion limits and their influence on the transmission quality of subscriber signals, an electronic model of the amplitude characteristic (AC) and analytical relations are needed that relate the probability of an error when registering the output signal of the communication channel with the nonlinearity of the AC NA and other destabilizing factors. The article compares alternative mathematical models of AC NA. In contrast to traditional methods of analysis, usually limited to the choice of models with fixed parameters, a method for variably determining the parameters of AC is considered. The results are: a comparison of known methods for approximating the AC of broadband nonlinear power amplifiers of radio signals is given, an algorithm for selecting model parameters for CDMA systems with QAM using the Rapp model is proposed.

HIGH POWER CHAOTIC OSCILLATOR

The article presents a novel design of a microwave chaotic oscillator. The oscillator contains an inertial converter for the nonlinear amplifier output signal that modulates the supply voltage of the transistor. When the inertia of the converter becomes less than 0.06, the oscillator demonstrates chaotic behavior. We present an experimental model of a chaotic oscillator based on a high power transistor 2T982A-2. The inertial converter circuit contains a diode that perform half-wave conversion of a part of the output signal and a RC circuit with a time constant equal to 0.05 of the duration of an oscillation at the central frequency of the oscillator. The output signal of the inertial converter has been applied to the emitter power supply circuit of the transistor. Modulation of the supply voltage caused the output signal of the oscillator to become a sequence of non-repeating oscillation trains with a random duration and initial phase. The frequency band of the generated chaos with an uneven power spectrum of 4 dB was in a range from 3.1 to 3.3 GHz with an integrated power of 1.2 W. The averaged spectral density of noise oscillations was 6 10-3 W / MHz. Efficiency of the oscillator was 15%.