UAV-Aided Two-Way Multi-User Relaying

Abstract

Unmanned aerial vehicle (UAV)-aided two-way relaying networks are designed, where a UAV is deployed to assist multiple pairs of users in their information exchange. There are two basic approaches for the user pairs' information exchange within a single time slot via the UAV relay. The first approach is based on full-duplex, where all participants operate in the full-duplex mode to transmit and receive signals simultaneously. However, all transceivers have to operate in the face of severe self-interference, which cannot be completely suppressed. The second approach is based on conventional half-duplex, where the users send their information to the UAV within a certain fraction of the time slot, and the UAV relays them within the remaining fraction to avoid the self-interference. In either approach, the joint bandwidth and power allocation maximizing the sum information exchange throughput under realistic resource and user throughput constraints poses a complex nonconvex problem. New inner approximations are proposed for developing path-following algorithms for their computation. Our numerical results show that the time-fraction-based half-duplex approach clearly outperforms the high-complexity full-duplex approach.

UAV-Enabled Ultra-Reliable Low-Latency Communications for 6G: A Comprehensive Survey

“…Moreover, UAVs are more likely to establish short-distance line-of-sight (LoS) communication links, thus providing better link qualities [19]. Then, the UAV communication has received significant research attention along the last years [20]- [27]. However, the majority works on UAV communications mainly focused on the data links while issues on the delay and reliability in the links between UAVs and the ground control station have recently started to gain attention and interest from both academia and industrial sectors.…”

A D2D assisted multi‐hop data dissemination protocol for inter‐UAV communication

“…1,2 UAVs offer two advantages in this regard: one is to collect data from a wide range of area due to their mobility, and second is to sense data from areas where installing sensors may be difficult. [3][4][5] Due to cost of placing UAVs, they may only be placed at strategic points for data collection. Therefore, communication among UAVs will be important to carry the sensed data to the central control centers (where data will be analyzed and decisions will be taken).…”

“…Future Internet of Things (IoT) will use mobile nodes such as unmanned aerial vehicles (UAVs) equipped with sensors to efficiently collect data from different geographical areas 1,2 . UAVs offer two advantages in this regard: one is to collect data from a wide range of area due to their mobility, and second is to sense data from areas where installing sensors may be difficult 3‐5 …”

Optimization for Signal Transmission and Reception in a Macrocell of Heterogeneous Uplinks and Downlinks

“…Even for microcells, it is impossible to control SI under a level so that the FDbased STR is more spectral-efficient or energy-efficient than the conventional half-duplexing (HD)-based transmission and reception, which transmit and receive signal in two separated time-slots, even by using the advanced techniques of signal processing [7]- [19]. Motivated by this unsolved issue of the FD exploitation, and also originated from [20], where the information and energy are proposed to be transferred separately over the same wireless channels within a time-slot instead of their simultaneous transfer, it was suggested in [19], [21], [22] to use a fraction of a time-slot to transmit signals to the relays and then the remaining complementary timefraction to forward the received signals at the relays to the destination end. Such time-fraction-wise half-duplexing (HD) relaying is not only much easier implemented but is much better than that using the FD-based relaying.…”