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In this study, we experimentally investigated the adjacent channel leakage ratio (ACLR) performance degradation for the output signal of the RF HPA equipped with the adaptive linearization caused by RoF links placed in both direct and feedback paths of the transmitting system. We show that ACLR exceeding -57 dBc @ 5 MHz offset, which completely satisfy the requirement defined in the 3GPP technical...
Radio over fiber (RoF) advanced technology is already integrated into existing 3G and 4G radio access networks where the digital unit and remote radio head equipped with the nonlinear high-power amplifiers are connected through RoF-based fronthaul links. In this study, we experimentally investigated the adaptive predistorter adjacent channel leakage (ACLR) ratio performance degradation caused by RoF...
This paper proposes a method for measuring the rapidly varying parameters of a power amplifier (PA) characterized by a memory polynomial model in less time than in the symbol period of the orthogonal frequency-division multiplexing (OFDM) signal of a long-term evolution-advanced (LTE-Advanced) system. The method fulfills the dual-updating scheme that we proposed in our previous papers, which described...
This paper proposes a method to measure complex valued transfer functions of linear time-invariant (LTI) circuits by assuming a memory polynomial model for a power amplifier (PA). To preserve phase information, the method uses cross-correlation of the device under test (DUT) with another PA without memory effect. This paper has clarified possibility that all coefficients in the memory polynomials...
This paper describes a method to design a predistorter (PD) for a power amplifier (PA) with a memory effect by using nonlinear parameters extracted from measured intermodulation distortion (IMD) for a GaN-FET amplifier. To improve the computational efficiency, the updating of a cancellation signal is provided by an iterative algorithm. It is confirmed that the proposed algorithm attains computational...
This paper presents clusterwise polarization characteristics based on an estimated MIMO channel of a small urban macrocell at 4.5 GHz. Polarization path gain, cross-polarization ratio, and co-polarization ratio characteristics as influenced by channel parameters such as delay, azimuth and elevation angle of arrival were investigated. Hypothesis testing was used as a verification of the results. This...
Clusters produced by multipath clusterization were comparatively evaluated using the directional power spectrum of the measured channel, which was obtained by polarimetric beamforming due to the dual-polarized nature of the channel sounding data. The clusters were from the results of the clusterization of maximum-likelihood-based path parameter estimates of a macrocell channel. The approach provides...
A novel ultra-wideband impulse radar architecture for 24-GHz-band short-range radar was developed using 0.13-mum InP high electron-mobility technology. The transmitter part generates an extremely wideband impulse from a pulse generator and then filters it through a bandpass filter. The obtained impulse had a full width at half maximum of 9 ps. Its frequency spectrum spread from dc to over 40 GHz and...
Multipath clusters in a wireless channel could act as additional channels for spatial multiplexing MIMO systems. However, identifying them in order to come up with better cluster channel models has been a hurdle due to how they are defined. This paper considers the identification of these clusters at the mobile station through a middle ground approach—combining a globally optimized automatic clustering...
This paper focuses on the modeling of a double-directional power spectrum density (PSD) between the base station (BS) and mobile station (MS) based on the site-specific measurements in an urban macrocell in Tokyo. First, the authors investigate the Kronecker separability of the joint polarimetric angular PSD between the BS and MS by using the ergodic mutual information. The general form of the sum...
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