Multi-HAPS Network Implementation within 3GPP’s NTN framework for 5G and beyond

High Altitude Platform Station (HAPS) is part of the 3GPP defined non-terrestrial network (NTN) infrastructure for 5G networks. Various technical studies by 3GPP have addressed NTN-based implementations and have significantly studied satellite-based scenarios. However, the study does not sufficiently address HAPS or multi-HAPS based scenarios specifically. Though HAPS, is captured under Unmanned Aerial Systems (UAS), it has unique operational realities that set it apart from other NTN platforms. For instance, HAPS come in different variants of fixed-wing, balloons and airships. This paper highlights the need for expanded studies specifically aimed at HAPS for more seamless integration. The work also analyses the Doppler effect associated with fixed-wing HAPS systems to further demonstrate how operational scenarios may differ for these platforms and the need for targeted studies. HAPS is expected to contribute significantly to the NTN-based implementations and may require more specialised considerations within the 3GPP NTN technical specification process, especially for 5G and beyond 5G (B5G) networks.

Predator–Prey Model Based Asymmetry Resource Allocation in Satellite–Terrestrial Network

In the traditional satellite networks, network resources are mainly allocated among all the satellites based on the same allocation algorithm. This kind of symmetry model limits the increase of throughput. In this paper, we study an asymmetry resource allocation method in a satellite–terrestrial network and propose a Lotka–Volterra based predator–prey model to achieve optimal resource allocation among different satellites. In the proposed satellite–terrestrial network, we divide all the satellites into two groups, and we try to achieve load stability between these two satellites groups. Using the predator–prey model, one group is the prey–satellites, which can obtain service requirements from mobile users. The other group is considered as predator–satellites, which can only obtain the loads from the group of the prey–satellites. Once the satellites are divided into two groups using the Lotka–Volterra model, the resource allocation problem among these satellites in two groups would be asymmetry resource. We prove the existence of solutions to the proposed model. Numerical simulation results are given to show the correctness and effectiveness of the proposed model.

On the Energy Performance of Iridium Satellite IoT Technology

Most Internet of Things (IoT) communication technologies rely on terrestrial network infrastructure. When such infrastructure is not available or does not provide sufficient coverage, satellite communication offers an alternative IoT connectivity solution. Satellite-enabled IoT devices are typically powered by a limited energy source. However, as of this writing, and to our best knowledge, the energy performance of satellite IoT technology has not been investigated. In this paper, we model and evaluate the energy performance of Iridium satellite technology for IoT devices. Our work is based on real hardware measurements. We provide average current consumption, device lifetime, and energy cost of data delivery results as a function of different parameters. Results show, among others, that an Iridium-enabled IoT device, running on a 2400 mAh battery and sending a 100-byte message every 100 min, may achieve a lifetime of 0.95 years. However, Iridium device energy performance decreases significantly with message rate.

Two-Tier Cache-Aided Full-Duplex Hybrid Satellite–Terrestrial Communication Networks

Enabling global Internet access is challenging for cellular-based Internet of Things (IoT) due to the limited range of terrestrial network services. One viable solution is to deploy IoT over satellite systems for coverage extension. However, operating a hybrid satellite-terrestrial network (STN) might incur high satellite bandwidth consumption and excessive service latency. Aiming to reduce the content delivery latency from the Internet-connected gateway to the users, this work proposes a wireless two-tier cache-enabled model with full-duplex transmissions where content caches are deployed at the satellite and ground station. A closed-form solution for the successful delivery probability (SDP) of the files is derived considering the requested content distributions and channel statistics. Then, the SDP performance under common caching policies can be conveniently evaluated. The results are also used to optimize cache placement under caching capacity constraints. Numerical results demonstrate the performance improvements of the proposed system over those of single-tier cache-aided and half-duplex transmission systems.

A Location Management Strategy for Satellite Internet Constellation

Satellites are currently the most effective means to achieve seamless global coverage of the Internet. Due to the frequent beam switching caused by the high-speed movement of satellites, it is too expensive to directly apply the location management strategy in the terrestrial network to the satellite Internet constellation (SIC). To build a web browsing platform based on satellite Internet, it is necessary to display the location of satellites and terminals in real time. For this reason, this paper proposes the location management strategy of SIC. It uses the characteristics of large and periodic satellite beam coverage in a certain period of time, redesigns the location management database structure, location registration mechanism and call delivery mechanism, and analyses and simulates the bit cost of location management. The result proves that compared with the traditional strategy, this strategy greatly reduces the cost of SIC.