Experimental evaluation of latency and energy efficiency for SMS transmission over a 3GPP NB-NTN using GEO satellites

Abstract The continuous evolution of mobile networks has driven the demand for ubiquitous connectivity, especially in remote areas in which terrestrial infrastructure is limited or economically unfeasible. In this context, non-terrestrial networks (NTNs) have emerged as key enablers of extended coverage beyond conventional cellular networks. 3 rd Generation Partnership Project (3GPP) Release 17 introduced adaptations to the narrowband Internet of Things (NB-IoT) to support NTN operation, thereby enabling low-complexity services over satellite links. In this study, the performance of short message service (SMS) transmission over a narrowband-NTN (NB-NTN) was experimentally investigated using commercial smartphones. A laboratory-based geostationary earth orbit (GEO) NTN emulation environment was developed to evaluate end-to-end latency and energy consumption in multiple scenarios, including uplink and downlink transmissions, different SMS payload sizes, modulation and coding scheme (MCS) levels, and hybrid automatic repeat request (HARQ) configurations. The results demonstrate that the SMS latency was determined primarily by the satellite propagation delay, message length, and MCS level, with HARQ introducing a negligible additional delay. Under good signal conditions, the improved link budget yielded more stable latency, whereas under weak signal conditions, HARQ increased the transmission reliability with a marginal effect on energy consumption. The payload size and transmission duration remained the dominant factors that affected energy consumption. For higher MCS levels, the latency was reduced by up to 92% compared with that at MCS 0. These findings confirm the NB-NTN operational feasibility for reliable SMS delivery over GEO satellite links, with HARQ providing increased reliability at low energy overhead.