109 research outputs found
Adaptive Multi-objective Optimization for Energy Efficient Interference Coordination in Multi-Cell Networks
In this paper, we investigate the distributed power allocation for multi-cell
OFDMA networks taking both energy efficiency and inter-cell interference (ICI)
mitigation into account. A performance metric termed as throughput contribution
is exploited to measure how ICI is effectively coordinated. To achieve a
distributed power allocation scheme for each base station (BS), the throughput
contribution of each BS to the network is first given based on a pricing
mechanism. Different from existing works, a biobjective problem is formulated
based on multi-objective optimization theory, which aims at maximizing the
throughput contribution of the BS to the network and minimizing its total power
consumption at the same time. Using the method of Pascoletti and Serafini
scalarization, the relationship between the varying parameters and minimal
solutions is revealed. Furthermore, to exploit the relationship an algorithm is
proposed based on which all the solutions on the boundary of the efficient set
can be achieved by adaptively adjusting the involved parameters. With the
obtained solution set, the decision maker has more choices on power allocation
schemes in terms of both energy consumption and throughput. Finally, the
performance of the algorithm is assessed by the simulation results.Comment: 29 page
How to Understand LMMSE Transceiver Design for MIMO Systems From Quadratic Matrix Programming
In this paper, a unified linear minimum mean-square-error (LMMSE) transceiver
design framework is investigated, which is suitable for a wide range of
wireless systems. The unified design is based on an elegant and powerful
mathematical programming technology termed as quadratic matrix programming
(QMP). Based on QMP it can be observed that for different wireless systems,
there are certain common characteristics which can be exploited to design LMMSE
transceivers e.g., the quadratic forms. It is also discovered that evolving
from a point-to-point MIMO system to various advanced wireless systems such as
multi-cell coordinated systems, multi-user MIMO systems, MIMO cognitive radio
systems, amplify-and-forward MIMO relaying systems and so on, the quadratic
nature is always kept and the LMMSE transceiver designs can always be carried
out via iteratively solving a number of QMP problems. A comprehensive framework
on how to solve QMP problems is also given. The work presented in this paper is
likely to be the first shoot for the transceiver design for the future
ever-changing wireless systems.Comment: 31 pages, 4 figures, Accepted by IET Communication
FlexEdge: Digital Twin-Enabled Task Offloading for UAV-Aided Vehicular Edge Computing
Integrating unmanned aerial vehicles (UAVs) into vehicular networks have
shown high potentials in affording intensive computing tasks. In this paper, we
study the digital twin driven vehicular edge computing networks for adaptively
computing resource management where an unmanned aerial vehicle (UAV) named
FlexEdge acts as a flying server. In particular, we first formulate an energy
consumption minimization problem by jointly optimizing UAV trajectory and
computation resource under the practical constraints. To address such a
challenging problem, we then build the computation offloading process as a
Markov decision process and propose a deep reinforcement learning-based
proximal policy optimization algorithm to dynamically learn the computation
offloading strategy and trajectory design policy. Numerical results indicate
that our proposed algorithm can achieve quick convergence rate and
significantly reduce the system energy consumption.Comment: 6 pages, 6 figure
Joint Transmitter Design for Robust Secure Radar-Communication Coexistence Systems
This paper investigates the spectrum sharing between a multiple-input
single-output (MISO) secure communication system and a multiple-input
multiple-output (MIMO) radar system in the presence of one suspicious
eavesdropper. We jointly design the radar waveform and communication
beamforming vector at the two systems, such that the interference between the
base station (BS) and radar is reduced, and the detrimental radar interference
to the communication system is enhanced to jam the eavesdropper, thereby
increasing secure information transmission performance. In particular, by
considering the imperfect channel state information (CSI) for the user and
eavesdropper, we maximize the worst-case secrecy rate at the user, while
ensuring the detection performance of radar system. To tackle this challenging
problem, we propose a two-layer robust cooperative algorithm based on the
S-lemma and semidefinite relaxation techniques. Simulation results demonstrate
that the proposed algorithm achieves significant secrecy rate gains over the
non-robust scheme. Furthermore, we illustrate the trade-off between secrecy
rate and detection probability
Blockchain-Based Identity Authentication Oriented to Multi-Cluster UAV Networking
Unmanned Aerial Vehicle (UAV) networking is increasingly used in field
environments such as power inspection, agricultural plant protection, and
emergency rescue. To guarantee UAV networking security, UAV identity
authentication attracts wide attention, especially in the field environment
without perfect infrastructure. Some blockchain-based UAV identity
authentication solutions are proposed to establish decentralized and trusted
authentication systems without relying on infrastructure. However, these
solutions do not support disconnected UAV reconnection or even disband a
cluster directly after its head UAV disconnection, which compromises cluster
robustness and task result integrity. In this paper, we propose a
blockchain-based identity authentication solution oriented to multi-cluster UAV
networking with a UAV disconnection mechanism and a task result backup
mechanism. Specifically, we build a blockchain maintained by head UAVs of all
clusters, managing identity information to guarantee the security of
decentralized identity management. The UAV disconnection mechanism permits a
verified distributed UAV reconnection to ensure the robustness of the UAV
cluster, and on this basis, the task result backup mechanism ensures the
integrity of the task results stored in a cluster even any UAV disconnection.
Finally, extensive experimental results prove the superiority of our solutions
in terms of robustness, integrity, delay, and energy consumption
SARS-CoV-2: The Monster Causes COVID-19
Coronaviruses are viruses whose particles look like crowns. SARS-CoV-2 is the seventh member of the human coronavirus family to cause COVID-19 which is regarded as a once-in-a-century pandemic worldwide. It holds has the characteristics of a pandemic, which has broy -55ught many serious negative impacts to human beings. It may take time for humans to fight the pandemic. In addition to humans, SARS-CoV-2 also infects animals such as cats. This review introduces the origins, structures, pathogenic mechanisms, characteristics of transmission, detection and diagnosis, evolution and variation of SARS-CoV-2. We summarized the clinical characteristics, the strategies for treatment and prevention of COVID-19, and analyzed the problems and challenges we face
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