چكيده به لاتين
Aerial vehicles have many advantages such as swift deployment, low capital and operational expenditure, coverage deployment in a wide geographical area, the possibility of free movement to improve the link quality in wireless networks.
These vehicles have two main roles in wireless networks. The first role is an Aerial service provider such as Base Stations (BSs), relays and etc. The second role is Aerial users which connect to the wireless networks.
In this thesis an aerial heterogeneous wireless system consists of a High Altitude Platform (HAP) and Low Altitude Platforms (LAPs) as Aerial Base Stations (ABSs) in a downlink OFDMA transmission is investigated. Two types of spectrum sharing including Spectrum Underlay Access (SUA) and Spectrum Overlay Access (SOA) for assessment of inter-tier interference are used. The placements of ABS and users-ABSs association are performed. Joint subcarriers assignment and power allocation in Spectral Efficiency (SE), Energy Efficiency (EE) and transmission power optimization problems is accomplished by the proposed two layers algorithm. At the first and second layers subcarrier assignment and power allocation are fulfilled, respectively. The simulation results show the relation between spectrum reuse and inter-tier interference. Such that, system SE, EE and the number of served users are maximized when both the spectrum reuse and the inter-tier interference management are performed together.
