A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles

In recent years, there has been a dramatic increase in the use of unmanned aerial vehicles (UAVs), particularly for small UAVs, due to their affordable prices, ease of availability, and ease of operability. Existing and future applications of UAVs include remote surveillance and monitoring, relief operations, package delivery, and communication backhaul infrastructure. Additionally, UAVs are envisioned as an important component of 5G wireless technology and beyond. The unique application scenarios for UAVs necessitate accurate air-to-ground (AG) propagation channel models for designing and evaluating UAV communication links for control/non-payload as well as payload data transmissions. These AG propagation models have not been investigated in detail when compared to terrestrial propagation models. In this paper, a comprehensive survey is provided on available AG channel measurement campaigns, large and small scale fading channel models, their limitations, and future research directions for UAV communication scenarios

Analysis of PAPR in OTFS modulation with classical selected mapping technique

Abstract Orthogonal Time Frequency Space (OTFS) is the advanced stage of modulation for this fast-growing generation. This is the waveform proposed to be used in next-generation communication systems i.e., 6G, as it has the advantage of high data rate, better flexibility, requires a less cyclic prefix and less amount of peak to average power ratio (PAPR) compared to Orthogonal Frequency Division Multiplexing (OFDM). To reduce the amount of PAPR in the OTFS, the best method is the classical selected mapping (SLM) technique. This paper presents the PAPR analysis in OTFS modulation by using classical SLM and the obtained results are compared against the OFDM modulation

A robust power control scheme for femtocell networks with probability constraint of channel gains

In this paper, a robust power control algorithm is proposed in two-tier femtocell network system in order to address the uncertain channel gains of the interference links. In the algorithm, an outage probability is used to guarantee the communication qualities of users. As the deterministic form of the outage probability constraint is not convex of power, a novel and simple method is utilized to solve the power allocation problem. The allocation solution can be determined based on the average channel gains which are engaged with a dynamic factor with average signal-to-interference-plus-noise ratio. In the scheme, a dynamic power adjustment algorithm is developed. The algorithm attempts to guarantee the outage probability requirement of the macrocell user, and to achieve the optimal power allocation of femtocell users. Apart from the appropriate resource for the network, an admission control algorithm is adopted to remove the femtocell user whose communication quality can not be ensured. Numerical results demonstrate the effectiveness of the robust power control algorithm and also explain the admission control algorithm