# A B5G Non-Terrestrial-Network (NTN) and Hybrid Constellation Based Data Collection System (DCS)
## 1 Introduction  
With the rapid development of beyond 5G (B5G) technologies, many traditional network services are being replaced by space technologies [1]. Especially in the descriptions of 3 GPP standards and the Beyond 5G roadmap [2], the non-terrestrial network (NTN) contains low-altitude platforms (LAP), high-altitude platforms (HAP), low-earth orbit satellites (LEO), medium earth orbit satellites (MEO), geostationary earth orbit satellites (GEO), and highly elliptical orbit satellites (HEO). Those multi-layer space platforms can be regarded as B5G remote access networks (RAN), B5G digital forwarding networks (DFN), B5G edge computing (EC) equipment, and B5G core networks (CN). Different applications of space platforms require different ground-supporting technologies [3]. For example, a gateway equipment is necessary for onboard B5G DFN, and large computing power is required for B5G CN. Massive Machine-Type Communications (mMTC) [4] is the main application sceneries of B5G [3]. The higher the altitude platform is, the larger ground coverage is. Comparing to traditional Internet of Things (IoT) systems, the non-terrestrial network-based massive Machine-Type Communications (NTN-mMTC) can achieve higher efficiency narrowband IoT. Large coverage and strong access abilities ensure global real-time data collection.  
Moreover, CubeSat is considered an excellent miniaturization application of satellite technology. The unit structure is a cube of 10 cm [5], which is defined as 1U. Each 1U weighs less than two kilograms. CubeSat has the advantages of miniaturization, low cost, and easy launch. However, a 1U CubeSat cannot contain a complete satellite system, which consists of satellite platforms and payloads. A 6U CubeSat is more suitable for space missions. However, the performance of CubeSat is limited due to size constraints [6]. Fortunately, a CubeSat constellation can make up for this default through collaboration. It contains multiple CubeSats that work together to complete integrated missions. For NTN-mMTC,CubeSat constellation can cooperate to complete distributed data collection system (DCS) tasks. This system can greatly enhance the data collection capabilities of ground sensors due to the advantages of global coverage and fast scanning [7]. However, the traditional satellite constellations require independent ground gateway stations. As an application scenario for B5G, NTN-mMTC can use B5G CN as ground infrastructure. Add a satellite-ground-link (GSL) to the RAN, and the traditional independent gateway ground station can be replaced by a B5G base station. This design will greatly reduce construction costs.  
Software-defined radio (SDR), an emerging communication technology, has been integrated with satellite technology. SDR-based satellite communication equipment and GSL communication equipment have become research hotspots. The most attractive advantage of SDR is reconfigurability. On a unified hardware platform, different communication functions can be realized by embedding different software packages. This feature is especially suitable for NTN-mMTC. For the reason that it needs to be compatible with many different modes of IoT signals.  
In this paper, a CubeSat constellation based on B5G NTN-mMTC DCS is proposed. Constellation topology design, CubeSat platform design, and DCS payload design are proposed. Many simulations and tests are applied to verify this design. Moreover, this design is applying for the engineering stage.