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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...
One of the major drawbacks of multicarrier transmission is the high peak-to-average power ratio (PAPR) of the transmit signal. In this paper, we propose a PAPR reduction technique for mixed-modulation multicarrier transmission into subcarriers. We show that the knowledge of the allocation of modulation schemes among the subcarriers gives an extra degree of freedom compared with traditional approaches,...
An adaptive predistorter is an effective technique to compensate for the nonlinear distortion of power amplifiers. To enable broadband communications, the bandwidth of communication systems has been continuously increased. With these increases in bandwidth, frequency distortions due to limitations in the bandwidth of the predistorter's building blocks can no longer be ignored. Such distortions are...
Abstract- Two closely related non-linear distortions are introduced to the frontend of a transmitting multicarrier signal: a clipping noise due to a high peak-to-average-power-ratio (PAPR) reduction and intermodulation distortions from the nonlinearity of high power amplifiers (HPAs). In recent years, there has been growing interest in various PAPR reduction and linearization techniques using predistortion...
An adaptive predistorter (PD) is an effective technique to compensate for the nonlinear distortion of power amplifiers. To enable broadband communications, the bandwidth of communication systems has had to continuously increase. With these increases in bandwidth, frequency distortions due to limitations in the bandwidth of the PD's building blocks can no longer be ignored. Such distortions are important...
This paper presents a new method of digital adaptive predistortion for linearization of high-power amplifiers (HPAs) that mitigates linearization performance deterioration due to bandwidth limitation of feedback path. With increases of signal bandwidth, the effects of limited bandwidth of the predistorter feedback path cannot be ignored. In the proposed algorithm, adaptation is derived from direct...
Often, to increase the efficiency of high-power amplifiers (HPAs), these amplifiers are driven into a nonlinear region. The nonlinearities in HPAs warp the signal constellation, increasing out-of-band radiation and causing both EVM and BER degradation. Digital predistortion (DPD) is one of the most promising linearization techniques that could lead to more efficient and cost-effective HPAs. The DPD...
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