Uplink subscriber channel analysis for non-terrestrial communication system

Introduction. In the era of digital progress, the demand for telecommunication services continues to grow, and their applications are expanding. However, many people still lack access to these services due to limited terrestrial coverage in remote areas. Non-Terrestrial networks, which integrate terrestrial and space-based components, can provide wider coverage while alleviating the load on terrestrial infrastructure. This technology involves deploying functions similar to those of a terrestrial base station on a satellite, an approach known as a regenerative payload. A key feature of this implementation is its ability to connect unmodified user devices directly to the satellite. However, this places stringent requirements on onboard equipment. The aim of this study is to assess the feasibility of providing communication via the uplink subscriber channel in a non-terrestrial network using the latest technological components. Methods. The analysis of the subscriber uplink channel parameters is based on a standard direct conversion receiver on board a spacecraft, utilizing third-generation terrestrial network technology. Results. The analysis of the subscriber channel revealed that while communication is fundamentally possible – achieving speeds of up to 144 kbps under favorable conditions and 12.2 kbps under unfavorable conditions – high transmission rates should not be expected due to significant signal attenuation along the transmission path. To overcome data rate limitations in the future, the adoption of more advanced communication technologies and signal processing methods should be considered, along with the use of lower transmission frequencies. The analysis of contemporary technological components demonstrated that state-of-the-art equipment enables processing across the entire 70 MHz frequency band allocated by the standard. Additionally, due to the high sampling frequency of modern ADCs, it is possible to enhance the dynamic range, achieving a gain of 3.5 dB when processing in a discrete system.