Optimizing Air-Borne Network-in-a-Box Deployment for Efficient Remote Coverage

Among many envisaged drivers for sixth generation (6G), one is from the United Nation's Sustainability Development Goals 2030 to eliminate digital inequality. Remote coverage in sparsely populated areas, difficult terrains or emergency scenarios requires on-demand access and flexible deployment with minimal capex and opex. In this context, network-in-a-box (NIB) is an exciting solution which packs the whole wireless network into a single portable and reconfigurable box to support multiple access technologies, such as WiFi, 2G-5G, etc. In this article, we propose low-altitude platform station (LAPS)-based NIBs with stratospheric high-altitude platform station (HAPS) as backhaul. Specifically, backhaul employs nonorthogonal multiple access (NOMA) with superposition coding at the transmitting HAPS and successive interference cancellation (SIC) at the receiving NIBs, whereas the access link (AL) employs superposition coding along with the regularized zero-forcing (RZF) precoding at the NIB in order to elevate the computational overhead from the ground users (GUs). The required number of airborne NIBs to serve a desired coverage area, their optimal placement, user association (UA), beam optimization, and resource allocation are optimized by maximizing the sum rate of the AL while maintaining the quality of service. Our findings reveal the significance of thorough system planning and communication parameters optimization for enhanced system performance and best coverage under limited resources.