Optimizing Disaster Response with tHAPs: Modeling and Coverage Analysis for Crisis Zones

In the 6G era, aerial base stations will significantly enhance cellular network coverage and capacity. Tethered High Altitude Platforms (tHAPs) present an effective solution to extend coverage in crisis zones, particularly when ground infrastructure is unavailable or damaged. This paper provides a comprehensive modeling and coverage analysis of tHAP systems, incorporating the hovering region, signal propagation based on the Hata model, and detailed link budget analysis for both uplink and downlink scenarios. Key parameters such as tether length, transmit power, antenna gains, and path loss are considered in the model. Simulation results demonstrate how varying tether lengths impact path loss, cell radius, and coverage probability. For example, increasing tether length from 100 m to 250 m at operating frequency of 1 GHz expands coverage but also increases the path loss by 13 dB. We also demonstrate that this increased path loss can be balanced with transmit power i.e., by increasing the transmit power from 43 dBm to 49 dBm improves signal strength by 10 dB. These results indicate that increasing the altitude of the tHAP enhances the coverage area, though it also leads to higher path loss. This trade-off between tether length and path loss is critical for optimizing the deployment of tHAP systems in crisis zones which is the focus of the paper.