Abstract-This paper studies receiver techniques for nonlinear amplifier distortion compensation in an OFDM relay-assisted cooperative communication system. The system model includes a nonlinear amplifier at the amplify-and-forward relay, modeled as a solid state power amplifier (SSPA). A maximum ratio combiner (MRC) is introduced that includes the effects of the amplifier distortions. The MRC is obtained by a proper modeling of the nonlinear distortion noise. Furthermore, we introduce a power amplifier nonlinearity cancellation (PANC) technique that is suitable for cooperative systems. Our simulation results confirm that the new MRC and PANC techniques offer substantial performance improvements if the relayed signal is subject to nonlinear distortion.
We propose the Vehicle-Originating-Signals (VOS) approach for charging control of a fleet of electric vehicles (EV) in an electricity distribution network. The goal of the approach is to manage the EV load such that the aggregate power consumption, including inflexible demand and solar generation, closely follows a given target profile. The VOS approach enables EVs in a fleet to compute signals reflecting their need for charge and willingness to supply power. An aggregator collects these signals and implements the control with minor computational effort. We evaluate the VOS approach on a scenario for Munich, Germany, based on a mobility survey and real electricity demand and solar generation data. First, we compare our approach against a centralized optimization in terms of objective fulfillment and solving time. We show that it achieves a competitive performance, especially for large vehicle fleets. Second, we present a statistical method to evaluate the performance and limitations of our approach. We identify a recommended range of the vehicle fleet size for a given load magnitude and show that the target profiles can be met with a defined certainty. Last, we present a method for further reducing the communication overhead with minor effect on performance.
We study alternative signal designs for electric vehicle (EV) charging control based on vehicle-originatingsignals (VOS). In the original VOS approach, the need-forcharge signal is proportional to a ratio between required and available charging times which results in a convex signal. We therefore consider alternative signal designs with different concavity and convexity and compare the results in terms of objective adherence and individual EV benefits. For the evaluation, we compare the original and alternative designs for the VOS approach on a load leveling scenario based on electricity demand, solar generation and car mobility data from Munich, Germany. Results show that significantly concave and extremely convex signals have a negative effect on both the error and the EVs, while linear and adaptively convex signals enable vehicles to achieve higher battery levels at earlier stages of the parking period with no significant effect on the error.
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