查看更多>>摘要：Since the computing capacity and battery energy of unmanned aerial vehicle(UAV)are constrained,UAV as aerial user is hard to handle the high computational complexity and time-sensitive applications.This paper investigates a cellular-connected multi-UAV network supported by mobile edge computing.Multiple UAVs carrying tasksfly from a given initial position toa termination position within a specified time.To handle the large number of tasks carried by UAVs,we propose a energy cost of all UAVs based problem to determine how many tasks should be offloaded to high-altitude balloons(HABs)for computing,where UAV-HAB association,the trajectory of UAV,and calculation task splitting are jointly optimized.However,the formulated problem has nonconvex structure.Hence,an efficient iterative algorithm by applying successive convex approximation and the block coordinate descent methods is put forward.Specifically,in each iteration,the UAV-HAB association,calculation task splitting,and UAV trajec-tory are alternately optimized.Especially,for the nonconvex UAV trajectory optimization problem,an approximate convex optimization problem is settled.The numerical results indicate that the scheme of this paper proposed is guaranteed to converge and also significantly reduces the entire power consumption of all UAVs compared to the benchmark schemes.
查看更多>>摘要：With the rapid development of wireless communications,cellular communication and distributed wire-less network are fragile to eavesdropping due to distributed users and transparent communication.However,to adopt bigger transmit power at a given area to interfere potential eavesdroppers not only incurs huge energy waste but also may suppresses regular communication in this area.To this end,we focus on secure communication in multi-hop wireless communication network,and propose two communicating while jamming schemes for secure communication in presence of potential eavesdroppers for the narrow band and broad band point-to-point(P2P)systems respectively with the aid of artificial noise transmitted by a chosen cooperative interferer.Furthermore,to achieve the end-to-end(E2E)multi-hop secure communication,we devise the secure network topology discovering scheme via constructing a proper network topology with at least one proper node as the cooperative interferer in each hop,and then propose the secure transmission path planning scheme to find an E2E secure transmission route from source to destination,respectively.Experiments on the wireless open-access research platform demonstrate the feasibility of the proposed schemes.Besides,simulations results validate that the proposed schemes can achieve better performance compared with existing methods in both the P2P communication case and E2E multi-hop communication network scenario.
查看更多>>摘要：With rising energy prices and concerns about environmental issues,energy-efficient driving strategies(EEDS)for high-speed trains have received a substantial amount of attention.In particular,energy-saving schemes play a huge role in reducing the energy and operating costs of trains.This article studies the EEDS of high-speed trains at a given time.A well-posed model is formulated,in which the constraints of the checkpoints,in addition to the speed limits,vehicle dynamics,and discrete control throttle,are first considered.For a given control sequence,the Karush-Kuhn-Tucker(KKT)conditions are used to obtain the necessary conditions for an EEDS.According to several key equations of the necessary conditions,the checkpoint constraints are satisfied.Some case studies are conducted based on the data of the Beijing-Shanghai high-speed line to illustrate the effectiveness of the proposed approach.
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