Height Optimization and Channel Gain based User Pairing for UAV-Assisted Emergency Communications

The Internet of Things (IOT) has been featured for its ability to connect and control numerous real and virtual objects with wireless communication systems. Recently, IOT has received wide popularity in beyond fifth generation communication systems also (B5G). To exploit both the energy efficiency and spectrum efficiency in a heterogeneous IOT networks, a promising technique named Non -Orthogonal Multiple Access (NOMA) is proved to be an effective one. Meanwhile, IOT is susceptible to an unexpected disaster which results in power cut and ultimately damage the system. To assist this emergency situation, Unmanned Aerial Vehicle (UAV) can be utilized for delivering messages from base stations (BSs) to the users present in the disaster region. In a heterogeneous IOT networks, all users and devices will be operated with batteries and once the disaster occurs, all base stations and users will be broken down. To handle this emergency situation, it is necessary to employ multiple UAVs. The signal is first sent to the UAVs stationed in the disaster region by UAVs deployed outside the disaster area. UAVs then transmit the signals to any devices that are within their coverage range. This article considers the problem of user clustering and three dimensional UAV location planning for NOMA-assisted multi-UAV emergency communication. Users are paired to perform NOMA scheme using uniform channel gain difference (UCGD) method. Moreover, this study utilize particle swarm optimization (PSO) algorithm to find the optimal location for multiple UAVs which maximizes the system sum rate. Extensive computer simulations have been carried out to validate the superiority of the proposed algorithms.