Showing papers by "Jeroen Wigard published in 2022"
10 Apr 2022
TL;DR: System-level simulations to evaluate the 5G NR mobility performance of the conditional handover (CHO) in a LEO-based NTN with Earth-moving cells scenario show that the CHO procedure reduces the radio link failures and handover failures but increases the unnecessary HO rate by more than 60% in comparison with the baseline HO, which leads to an increase of the signalling and measurement reporting.
Abstract: The development of non-terrestrial networks (NTN) aims to satisfy the requirements of ubiquitous and seamless coverage for fifth-generation (5G) services. Low Earth orbit (LEO) satellites introduce challenging mobility requirements to the 5G New Radio (NR) radio resource management procedures. Current research shows that the baseline 5G NR UE-assisted network-controlled handover (HO) procedure, meant for terrestrial scenarios, fails to ensure continuous and satisfactory service in LEO-based NTN. The conditional handover (CHO), specified by 3GPP in Rel-16, was designed for terrestrial networks to enhance mobility robustness by making HO decisions earlier. In this work, we conduct system-level simulations to evaluate the 5G NR mobility performance of the CHO in a LEO-based NTN with Earth-moving cells scenario. The simulation results show that the CHO procedure reduces the radio link failures and handover failures to 0 but increases the unnecessary HO rate by more than 60% in comparison with the baseline HO, which leads to an increase of the signalling and measurement reporting. Finally, future research directions are identified to address the increase of the signalling overhead by exploiting the predictability of the satellite’s movement.
4 citations
TL;DR: In this article , the authors provide a mobility performance analysis through extensive system-level simulations of state-of-the-art HO procedures for 5G NR over LEO satellite networks with Earth-moving cells.
Abstract: Low-Earth orbit (LEO) satellite networks are meant to be fundamental to closing the digital divide, enabling new market opportunities and providing fifth-generation (5G) New Radio (NR) connectivity everywhere at any time. Despite the advantages of LEO deployments, these systems are characterized by a high mobility and a challenging propagation channel that compromise several procedures of the current 5G standards. One of the impacted areas is the radio mobility management, which is used to ensure continuous and satisfactory service while users handover among cells. Current research shows that the measurement-based 5G NR handover (HO) procedures, designed for terrestrial networks, fail to ensure optimal mobility performance. In this work, we provide a mobility performance analysis through extensive system-level simulations of state-of-the-art HO procedures for 5G NR over LEO satellite networks with Earth-moving cells. Furthermore, this article presents a novel antenna gain-based HO solution for intra-satellite mobility that exploits the predictability of the satellites movement and the antenna gain of the satellite beams, making user equipment (UE)’s radio measurements obsolete. The system-level simulation results, which consider users in rural and urban scenarios, show that by exploiting the known satellite’s trajectory, the UE eliminates service failures and undesired HO events, maximises the time-of-stay in a cell and experiences improved downlink signal-to-interference-plus-noise ratio. This article also includes a sensitivity study of the impact on the mobility performance of satellite-specific and UE-specific errors such as the UE’s location error, the satellite beam’s antenna radiation error and the satellite’s pointing error. Finally, the impact of the UE’s mobility is analyzed.
1 citations
01 Jun 2022
TL;DR: In this article , a location-based HO triggering event was proposed to exploit the predictable movement of LEO satellites and uses the distance between the user's location and the center of the moving cells on the ground.
Abstract: Broadband low Earth orbit (LEO) satellite constellations are a reality. The integration of satellite and terrestrial systems for mobile communications is taking-off with the development of non-terrestrial networks (NTN) and the ongoing deployment of private constellations. Due to the highly mobile nature of LEO satellites, one of the critical research areas is the design of the mobility mechanisms to ensure robust service continuity for the end-user. Recent studies in the domain of Earth-moving cells have shown that measurement-based handover (HO) triggering events cannot guarantee a low number of radio link failures without an increase in signalling and measurement reporting. In this work, we present a new HO triggering event that exploits the predictable movement of LEO satellites and uses the distance between the user’s location and the centre of the moving cells on the ground. The performance of the proposed solution is evaluated with system-level simulations and compared against the measurement-based baseline HO and Rel-16 Conditional HO (CHO). It is found that the location-based HO triggering event completely eliminates the HO failures as well as unnecessary HOs and ping-pongs. As a result, the location-based HO triggering event extends the mean time-of-stay from values below 2 s to 4.8 s where the optimal mean time-of-stay is 4.9 s.
1 citations
04 Dec 2022
TL;DR: In this article , a camera-equipped UAV, streaming a live event, coexists with a large number of ground user equipment (gUEs) belonging to people attending the same event, and using the network to transmit their data.
Abstract: We focus in this paper on Cellular-connected Uncrewed Aerial Vehicles (UAVs) in a scenario of a camera-equipped UAV, streaming a live event. The UAV coexists with a large number of ground User Equipment (gUEs) belonging to people attending the same event, and using the network to transmit their data. Hence the cellular network must satisfy the high data rate demand of both the UAV and gUEs. For that, we explore interference mitigation solutions, and propose a novel algorithm for UAV cell-selection which minimizes the impact of the UAV to the concerned serving cell. The results demonstrate an uplink data-rate gain of 32% for gUEs in the crowded cell, compared to the standard algorithm, while achieving a target UAV throughput of 20 Mbps. This comes at a cost of increased UAV transmission power of 50% and a slight data rate degradation for gUEs in neighboring cells, up to 13%.
10 Apr 2022
TL;DR: A data-driven approach is evaluated to estimate the expected serving signal level of a UAV planning to fly along a specific path, based on the aggregation of measurements of UAVs that have previously been flying along the same route to achieve an estimation error as low as 2.7 dB.
Abstract: One of the key enablers for the use of cellular networks to provide connectivity to Unmanned Aerial Vehicles (UAVs) is reliability assurance. Estimating accurately the expected service availability and reliability that a UAV will experience along a planned route, helps to avoid critical situations. In this paper, we evaluate the use of a data-driven approach to estimate the expected serving signal level of a UAV planning to fly along a specific path. The estimation approach, presented in a previous study for the ground-level case, is based on the aggregation of measurements of UAVs that have previously been flying along the same route. Using this approach we achieve an estimation error as low as 2.7 dB. Based on the estimations we calculate the expected outage probability in terms of service availability and reliability and provide estimations of the expected critical areas along the route. Results show that 90% of the availability and 65% of the reliability critical areas in the route can be accurately estimated.