1,661 research outputs found
Joint Trajectory and Communication Design for UAV-Enabled Multiple Access
Unmanned aerial vehicles (UAVs) have attracted significant interest recently
in wireless communication due to their high maneuverability, flexible
deployment, and low cost. This paper studies a UAV-enabled wireless network
where the UAV is employed as an aerial mobile base station (BS) to serve a
group of users on the ground. To achieve fair performance among users, we
maximize the minimum throughput over all ground users by jointly optimizing the
multiuser communication scheduling and UAV trajectory over a finite horizon.
The formulated problem is shown to be a mixed integer non-convex optimization
problem that is difficult to solve in general. We thus propose an efficient
iterative algorithm by applying the block coordinate descent and successive
convex optimization techniques, which is guaranteed to converge to at least a
locally optimal solution. To achieve fast convergence and stable throughput, we
further propose a low-complexity initialization scheme for the UAV trajectory
design based on the simple circular trajectory. Extensive simulation results
are provided which show significant throughput gains of the proposed design as
compared to other benchmark schemes.Comment: Submitted for possible publicatio
Capacity of UAV-Enabled Multicast Channel: Joint Trajectory Design and Power Allocation
This paper studies an unmanned aerial vehicle (UAV)-enabled multicast
channel, in which a UAV serves as a mobile transmitter to deliver common
information to a set of ground users. We aim to characterize the capacity
of this channel over a finite UAV communication period, subject to its maximum
speed constraint and an average transmit power constraint. To achieve the
capacity, the UAV should use a sufficiently long code that spans over its whole
communication period. Accordingly, the multicast channel capacity is achieved
via maximizing the minimum achievable time-averaged rates of the users, by
jointly optimizing the UAV's trajectory and transmit power allocation over
time. However, this problem is non-convex and difficult to be solved optimally.
To tackle this problem, we first consider a relaxed problem by ignoring the
maximum UAV speed constraint, and obtain its globally optimal solution via the
Lagrange dual method. The optimal solution reveals that the UAV should hover
above a finite number of ground locations, with the optimal hovering duration
and transmit power at each location. Next, based on such a
multi-location-hovering solution, we present a successive hover-and-fly
trajectory design and obtain the corresponding optimal transmit power
allocation for the case with the maximum UAV speed constraint. Numerical
results show that our proposed joint UAV trajectory and transmit power
optimization significantly improves the achievable rate of the UAV-enabled
multicast channel, and also greatly outperforms the conventional multicast
channel with a fixed-location transmitter.Comment: To appear in the IEEE International Conference on Communications
(ICC), 201
A Comprehensive Overview on 5G-and-Beyond Networks with UAVs: From Communications to Sensing and Intelligence
Due to the advancements in cellular technologies and the dense deployment of
cellular infrastructure, integrating unmanned aerial vehicles (UAVs) into the
fifth-generation (5G) and beyond cellular networks is a promising solution to
achieve safe UAV operation as well as enabling diversified applications with
mission-specific payload data delivery. In particular, 5G networks need to
support three typical usage scenarios, namely, enhanced mobile broadband
(eMBB), ultra-reliable low-latency communications (URLLC), and massive
machine-type communications (mMTC). On the one hand, UAVs can be leveraged as
cost-effective aerial platforms to provide ground users with enhanced
communication services by exploiting their high cruising altitude and
controllable maneuverability in three-dimensional (3D) space. On the other
hand, providing such communication services simultaneously for both UAV and
ground users poses new challenges due to the need for ubiquitous 3D signal
coverage as well as the strong air-ground network interference. Besides the
requirement of high-performance wireless communications, the ability to support
effective and efficient sensing as well as network intelligence is also
essential for 5G-and-beyond 3D heterogeneous wireless networks with coexisting
aerial and ground users. In this paper, we provide a comprehensive overview of
the latest research efforts on integrating UAVs into cellular networks, with an
emphasis on how to exploit advanced techniques (e.g., intelligent reflecting
surface, short packet transmission, energy harvesting, joint communication and
radar sensing, and edge intelligence) to meet the diversified service
requirements of next-generation wireless systems. Moreover, we highlight
important directions for further investigation in future work.Comment: Accepted by IEEE JSA
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