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1. An FSO-based Drone Assisted Mobile Access Network for Emergency Communications

   https://doi.org/10.1109/TNSE.2019.2942266  

   Wu, Di ; Sun, Xiang ; Ansari, Nirwan ( September 2019 , IEEE Transactions on Network Science and Engineering)

   Deploying drone-mounted base stations (DBSs) can quickly recover the communications of the mobile users (MUs) in a disaster struck area. That is, the DBSs can act as relay nodes to transmit data from remote working base stations to the MUs. Since the DBSs could be deployed very close to the MUs, the access link data rates between the DBSs and the MUs are well provisioned. However, the DBSs may be far away from the remote working base stations, and thus the backhaul link data rate between a DBS and the remote working base station could be throttled. Free Space Optics (FSO), which has been demonstrated to provision high speed point-to-point wireless communications, can be leveraged to improve the capacity of the backhaul link. Since FSO requires line-of-sight between a DBS and a remote working macro base station, DBSs have to carefully deployed. In this paper, we design a QoS aware drone base station placement and mobile user association strategy (RESCUE) to jointly optimize the DBS deployment, MU association, and bandwidth allocation such that the number of the served MUs in the disaster struck area could be maximized. The performance of RESCUE is validated via extensive simulations. 

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2. Backhaul-Aware Uplink Communications in Full-Duplex DBS-Aided HetNets

   https://doi.org/10.1109/GLOBECOM38437.2019.9013471  

   Zhang, Liang ; Ansari, Nirwan ( December 2019 , 2019 IEEE Global Communications Conference (GLOBECOM))

   Drone-mounted base stations (DBSs) are promising solutions to provide ubiquitous connections to users and support many applications in the fifth generation of mobile networks while full duplex communications has the potential to improve the spectrum efficiency. In this paper, we have investigated the backhaul-aware uplink communications in a full-duplex DBS-aided HetNet (BUD) problem with the objective to maximize the total throughput of the network, and this problem is decomposed into two sub-problems: the DBS Placement problem (including the vertical position and horizontal position) and the joint UE association, power and bandwidth assignment (Joint-UPB) problem. Since the BUD problem is NP- hard, we propose approximation algorithms to solve the sub-problems and another, named the AA-BUD algorithm, to solve the BUD problem with guaranteed performance. The performance of the AA- BUD algorithm has been demonstrated via extensive simulations, and results show that the AA-BUD algorithm is superior to two benchmark algorithms. 

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3. Joint Link-level and Network-level Reconfiguration for mmWave Backhaul Survivability in Urban Environments

   https://doi.org/10.1145/3345768.3355913  

   Liu, Yuchen ; Hu, Qiang ; Blough, Douglas M. ( January 2019 , Proceedings of the 22nd International ACM Conference on Modeling, Analysis and Simulation of Wireless and Mobile Systems)

   mmWave communication has been recognized as a highly promising technology for 5G wireless backhaul, which is capable of providing multi-gigabit per second transmission rates. However, in urban wireless backhaul environments, unforeseen events can cause short-term blockages or node failures and, therefore, network survivability is extremely important. In this paper, we investigate a novel relay-assisted mmWave backhaul network architecture, where a number of small-cell BSs and relays are deployed, e.g. on the lampposts of urban streets. Relays are used to provide multi-hop line-of-sight paths between small-cell BSs, which form logical links of the network. In this scenario, the interconnected logical links make up a mesh network, which offers opportunities for both link-level and network-level reconfiguration. We propose two joint link-network level reconfiguration schemes for recovery after exceptional events. One prioritizes relay path (link-level) reconfiguration and uses alternate network-level paths only if necessary. The other splits traffic on both reconfigured links and backup paths to improve network throughput. Simulation results demonstrate that the proposed schemes significantly outperform purely link-level and purely network-level reconfiguration schemes. The proposed approaches are shown to not only maintain high network throughput but to also provide robust blockage/fault tolerance across a range of scenarios for urban mmWave backhaul networks. 

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4. UAV-Based in-band Integrated Access and Backhaul for 5G Communications

   Fouda, Abdurrahman ; Ibrahim, Ahmed S ; Guvenc, Ismail ; Ghosh, Monisha ( October 2018 , IEEE Vehicular Technology Conference (VTC2018-Fall))

   We introduce the concept of using unmanned aerial vehicles (UAVs) as drone base stations for in-band Integrated Access and Backhaul (IB-IAB) scenarios for 5G networks. We first present a system model for forward link transmissions in an IB-IAB multi-tier drone cellular network. We then investigate the key challenges of this scenario and propose a framework that utilizes the flying capabilities of the UAVs as the main degree of freedom to find the optimal precoder design for the backhaul links, user-base station association, UAV 3D hovering locations, and power allocations. We discuss how the proposed algorithm can be utilized to optimize the network performance in both large and small scales. Finally, we use an exhaustive search-based solution to demonstrate the performance gains that can be achieved from the presented algorithm in terms of the received signal to interference plus noise ratio (SINR) and overall network sum-rate. 

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5. All-in-One Urban Mobility Mapping Application with Optional Routing Capabilities

   Thompson, R. ; Stovall, J. ; Valasquez, D. ; Anne, V. ; Samoylov, A. V. ; & Sartipi, M. ( December 2018 , Big data)

   To create safer and less congested traffic operating environments researchers at the University of Tennessee at Chattanooga (UTC) and the Georgia Tech Research Institute (GTRI) have fostered a vision of cooperative sensing and cooperative mobility. This vision is realized in a mobile application that combines visual data extracted from cameras on roadway infrastructure with a user’s coordinates via a GPS-enabled device to create a visual representation of the driving or walking environment surrounding the application user. By merging the concepts of computer vision, object detection, and mono-vision image depth calculation, this application is able to gather absolute Global Positioning System (GPS) coordinates from a user’s mobile device and combine them with relative GPS coordinates determined by the infrastructure cameras and determine the position of vehicles and pedestrians without the knowledge of their absolute GPS coordinates. The joined data is then used by an iOS mobile application to display a map showing the location of other entities such as vehicles, pedestrians, and obstacles creating a real-time visual representation of the surrounding area prior to the area appearing in the user’s visual perspective. Furthermore, a feature was implemented to display routing by using the results of a traffic scenario that was analyzed by rerouting algorithms in a simulated environment. By displaying where proximal entities are concentrated and showing recommended optional routes, users have the ability to be more informed and aware when making traffic decisions helping ensure a higher level of overall safety on our roadways. This vision would not be possible without high speed gigabit network infrastructure installed in Chattanooga, Tennessee and UTC’s wireless testbed, which was used to test many functions of this application. This network was required to reduce the latency of the massive amount of data generated by the infrastructure and vehicles that utilize the testbed; having results from this data come back in real-time is a critical component. 

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