Abstract
UAV equipped three-dimensional (3D) wireless networks can provide a solution for the requirements of 5G communications, such as enhanced Mobile Broadband (eMBB) and massive Machine Type Communications (mMTC). Especially, the introduction of an unmanned aerial vehicle (UAV) as a relay node can improve the connectivity, extend the terrestrial base station (BS) coverage and enhance the throughput by taking advantage of a strong air-to-ground line of sight (LOS) channel. In this paper, we consider the deployment and resource allocation of UAV relay network (URN) to maximize the throughput of user equipment (UE) within a cell, while guaranteeing a reliable transmission to UE outside the coverage of BS. To this end, we formulate joint UAV deployment and resource allocation problems, whose analytical solutions can be hardly obtained, in general. We propose a fast and practical algorithm to provide the optimal solution for the number of transmit time slots and the UAV relay location in a sequential manner. The transmit power at BS and UAV is determined in advance based on the availability of channel state information (CSI). Simulation results demonstrate that the proposed algorithms can significantly reduce the computational effort and complexity to determine the optimal UAV location and transmit time slots over an exhaustive search.
Highlights
As one of the diverse emerging applications of unmanned aerial vehicles (UAV), it can be utilized as an aerial base station (BS) or an aerial relay node in three-dimensional (3D) wireless networks to satisfy the service requirement of the fifth generation (5G) communication [1,2,3,4], such as enhanced Mobile Broadband and massive MachineType Communications
We propose the fast and practical UAV deployment and transmit time allocation (UDTA) algorithm, which consists of a novel time slot determination (TSD) algorithm and UAV deployment (UD) algorithm that determines the optimal number of transmit time slots and optimal UAV location, respectively
To cope with this issue, we introduce the expected channel model in a ground-to-ground link (i.e., BS-to-CU link in UAV relay network (URN)) because the effect of random fluctuation by small-scale fading during multiple time slots is negligible and it is impractical to adjust the location of UAV for the short period of each time slot
Summary
As one of the diverse emerging applications of unmanned aerial vehicles (UAV), it can be utilized as an aerial base station (BS) or an aerial relay node in three-dimensional (3D) wireless networks to satisfy the service requirement of the fifth generation (5G) communication [1,2,3,4], such as enhanced Mobile Broadband (eMBB) and massive Machine. [18] adopts multiple transmit time slots (>2) and derives the maximum distance between UAVs to achieve a reliable relay transmission It does not consider the optimal height of UAV and the performance analysis may not be applicable in all circumstances due to a fixed height of UAVs. Research on URN to optimize both UAV deployment and resource allocation during multiple transmit time slots (>2) can be rarely found due to the following two main reasons;. Multiple transmit time slots are utilized in URN, but the minimum number of overall transmit time slots is considered in a relay transmission for efficient resource management and without performance degradation of UEs within its original coverage due to reduced service opportunity by the BS.
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