Opportunistic relaying over Aerial-to-Terrestrial and Device-to-Device radio channels

To enable the rapid deployment of a public safety communication network, a novel system architecture integrating an aerial base station mounted on a low-altitude platform has drawn many attentions. However, the signal coverage provided by such a rapidly-deployed network is patchy and unstable, which conflict with the high requirement on link reliability in the case of disaster relief and emergency events. Opportunistic relaying is a simple but effective method to reap the spatial diversity in cooperative systems. It can be used to increase the link resilience and improve the system robustness in such a rapidly-deployed and highly-dynamic network. Until now, the theoretical analyses and performance evaluations regarding the opportunistic relaying are merely based on the idealized small-scale fading, i.e., Rayleigh or Rician, without taking into account the path loss and shadowing. To close that gap, therefore, we study the existing channel models and choose the most appropriate ones reflecting the realistic characteristics of Aerial-to-Terrestrial and Device-to-Device channels. In this paper, the impacts of power allocation strategies, carrier frequencies, number of relays, altitudes of low-altitude platform and distances among terminals on spectral efficiencies of opportunistic relaying over Aerial-to-Terrestrial and Device-to-Device radio channels are investigated.