188 research outputs found
Power vs. Spectrum 2-D Sensing in Energy Harvesting Cognitive Radio Networks
Energy harvester based cognitive radio is a promising solution to address the
shortage of both spectrum and energy. Since the spectrum access and power
consumption patterns are interdependent, and the power value harvested from
certain environmental sources are spatially correlated, the new power dimension
could provide additional information to enhance the spectrum sensing accuracy.
In this paper, the Markovian behavior of the primary users is considered, based
on which we adopt a hidden input Markov model to specify the primary vs.
secondary dynamics in the system. Accordingly, we propose a 2-D spectrum and
power (harvested) sensing scheme to improve the primary user detection
performance, which is also capable of estimating the primary transmit power
level. Theoretical and simulated results demonstrate the effectiveness of the
proposed scheme, in term of the performance gain achieved by considering the
new power dimension. To the best of our knowledge, this is the first work to
jointly consider the spectrum and power dimensions for the cognitive primary
user detection problem
Irregular Traffic Time Series Forecasting Based on Asynchronous Spatio-Temporal Graph Convolutional Network
Accurate traffic forecasting at intersections governed by intelligent traffic
signals is critical for the advancement of an effective intelligent traffic
signal control system. However, due to the irregular traffic time series
produced by intelligent intersections, the traffic forecasting task becomes
much more intractable and imposes three major new challenges: 1) asynchronous
spatial dependency, 2) irregular temporal dependency among traffic data, and 3)
variable-length sequence to be predicted, which severely impede the performance
of current traffic forecasting methods. To this end, we propose an Asynchronous
Spatio-tEmporal graph convolutional nEtwoRk (ASeer) to predict the traffic
states of the lanes entering intelligent intersections in a future time window.
Specifically, by linking lanes via a traffic diffusion graph, we first propose
an Asynchronous Graph Diffusion Network to model the asynchronous spatial
dependency between the time-misaligned traffic state measurements of lanes.
After that, to capture the temporal dependency within irregular traffic state
sequence, a learnable personalized time encoding is devised to embed the
continuous time for each lane. Then we propose a Transformable Time-aware
Convolution Network that learns meta-filters to derive time-aware convolution
filters with transformable filter sizes for efficient temporal convolution on
the irregular sequence. Furthermore, a Semi-Autoregressive Prediction Network
consisting of a state evolution unit and a semiautoregressive predictor is
designed to effectively and efficiently predict variable-length traffic state
sequences. Extensive experiments on two real-world datasets demonstrate the
effectiveness of ASeer in six metrics
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