154 research outputs found
Energy Efficient Spectrum Sensing for State Estimation over A Wireless Channel
The performance of remote estimation over wireless channel is strongly
affected by sensor data losses due to interference. Although the impact of
interference can be alleviated by performing spectrum sensing and then
transmitting only when the channel is clear, the introduction of spectrum
sensing also incurs extra energy expenditure. In this paper, we investigate the
problem of energy efficient spectrum sensing for state estimation of a general
linear dynamic system, and formulate an optimization problem which minimizes
the total sensor energy consumption while guaranteeing a desired level of
estimation performance. The optimal solution is evaluated through both
analytical and simulation results.Comment: 4 pages, 6 figures, accepted to IEEE GlobalSIP 201
A Scalable Hybrid MAC Protocol for Massive M2M Networks
In Machine to Machine (M2M) networks, a robust Medium Access Control (MAC)
protocol is crucial to enable numerous machine-type devices to concurrently
access the channel. Most literatures focus on developing simplex (reservation
or contention based)MAC protocols which cannot provide a scalable solution for
M2M networks with large number of devices. In this paper, a frame-based Hybrid
MAC scheme, which consists of a contention period and a transmission period, is
proposed for M2M networks. In the proposed scheme, the devices firstly contend
the transmission opportunities during the contention period, only the
successful devices will be assigned a time slot for transmission during the
transmission period. To balance the tradeoff between the contention and
transmission period in each frame, an optimization problem is formulated to
maximize the system throughput by finding the optimal contending probability
during contention period and optimal number of devices that can transmit during
transmission period. A practical hybrid MAC protocol is designed to implement
the proposed scheme. The analytical and simulation results demonstrate the
effectiveness of the proposed Hybrid MAC protocol
Real-Time Misbehavior Detection in IEEE 802.11e Based WLANs
The Enhanced Distributed Channel Access (EDCA) specification in the IEEE
802.11e standard supports heterogeneous backoff parameters and arbitration
inter-frame space (AIFS), which makes a selfish node easy to manipulate these
parameters and misbehave. In this case, the network-wide fairness cannot be
achieved any longer. Many existing misbehavior detectors, primarily designed
for legacy IEEE 802.11 networks, become inapplicable in such a heterogeneous
network configuration. In this paper, we propose a novel real-time hybrid-share
(HS) misbehavior detector for IEEE 802.11e based wireless local area networks
(WLANs). The detector keeps updating its state based on every successful
transmission and makes detection decisions by comparing its state with a
threshold. We develop mathematical analysis of the detector performance in
terms of both false positive rate and average detection rate. Numerical results
show that the proposed detector can effectively detect both contention window
based and AIFS based misbehavior with only a short detection window.Comment: Accepted to IEEE Globecom 201
Forces inside a strongly-coupled scalar nucleon
We investigate the gravitational form factors of a strongly coupled scalar
theory that mimic the interaction between the nucleon and the pion. The
non-perturbative calculation is based on the light-front Hamiltonian formalism.
We renormalize the energy-momentum tensor with a Fock sector dependent scheme.
We also systematically analyze the Lorentz structure of the energy-momentum
tensor and identify the suitable hadron matrix elements to extract the form
factors, avoiding the contamination of spurious contributions. We verify that
the extracted form factors obey momentum conservation as well as the mechanical
stability condition. From the gravitational form factors, we compute the energy
and pressure distributions of the system. Furthermore, we show that utilizing
the Hamiltonian eigenvalue equation, the off-diagonal Fock sector contributions
from the interaction term can be converted to diagonal Fock sector
contributions, yielding a systematic non-perturbative light-front wave function
representation of the energies and forces inside the system.Comment: 30 pages, 21 figure
A Lightweight Sensor Scheduler Based on AoI Function for Remote State Estimation over Lossy Wireless Channels
This paper investigates the problem of sensor scheduling for remotely
estimating the states of heterogeneous dynamical systems over resource-limited
and lossy wireless channels. Considering the low time complexity and high
versatility requirements of schedulers deployed on the transport layer, we
propose a lightweight scheduler based on an Age of Information (AoI) function
built with the tight scalar upper bound of the remote estimation error. We show
that the proposed scheduler is indexable and sub-optimal. We derive an upper
and a lower bound of the proposed scheduler and give stability conditions for
estimation error. Numerical simulations demonstrate that, compared to existing
policies, the proposed scheduler achieves estimation performance very close to
the optimal at a much lower computation time
Energy-Efficient Spectrum Sensing for Cognitive Radio Enabled Remote State Estimation Over Wireless Channels
The performance of remote estimation over wireless channels is strongly affected by sensor data losses due to interference. Although the impact of interference can be alleviated by applying cognitive radio technique which features in spectrum sensing and transmitting data only on clear channels, the introduction of spectrum sensing incurs extra energy expenditure. In this paper, we investigate the problem of energy-efficient spectrum sensing for remotely estimating the state of a general linear dynamic system, and formulate an optimization problem which minimizes the total sensor energy consumption while guaranteeing a desired level of estimation performance. We model the problem as a mixed integer nonlinear program and propose a simulated annealing based optimization algorithm which jointly addresses when to perform sensing, which channels to sense, in what order and how long to scan each channel. Simulation results demonstrate that the proposed algorithm well balances the sensing energy and transmission energy expenditure and can achieve the desired estimation performance
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