# Development and Evaluation of a LiFi-Transceiver Module for TMTC Intra-Satellite Communication +
## 1 Introduction  
The reliable interconnection of subsystems on a satellite platform is essential for ensuring optimal performance, but it also gives rise to complex wiring harnesses that compromise reliability, contribute to increased mass overhead [1] and hinder the flexibility of Assembly-, Integration- and Testing-Phase (AIT) processes [2]. Consequently, research into wireless data transmission for intra-satellite communication between subsystems has been an area of significant interest for many years.  
Several studies have explored the use of Radio Frequency (RF)-based methods, such as the Ultra Wide Band (UWB) [3, 4, 5], demonstrating promising results in CubeSat platforms. However, these approaches also come with inherent disadvantages, including the potential for Electromagnetic Interference (EMI) with other sub-components and susceptibility to interference by themselves, thereby posing a security risk through spoofing or jamming [6].  
To overcome the limitations of RF-based solutions, the Satellight [7] project aims to use wireless communication through a completely new approach via LiFi [8]. Unlike conventional optical communication methods, LiFi does not require fiber optic cables, and transmission takes place in free space. In addition, it adds no EMI to the satellite, cannot be interfered with or read from outside the satellite structure and offers a high bandwidth for both redundant channels for reliable transmissions or high data rate transmissions.  
In addition, the use of LiFi offers further advantages, especially in terms of meeting different requirements, such as the direct connection of external modules withoutoptical-electrical conversion, but it also supports the energy-autonomous operation of micro-components using energy from light (e.g., sensors) [9]. Like RF-based solutions, the elimination of a large part of the harness reduces assembly times and potential problems caused by faulty cabling.  
The advantages of the _SatelLight_ approach can be summarized as follows:  
* Significant reduction in the harness and thus savings in mass, assembly time and the avoidance of potential sources of error.
* In contrast to RF solutions, LiFi does not emit any EM radiation and therefore does not interfere with electronic components.
* LiFi transmission is completely shielded within the satellite structure and therefore cannot be interfered with or tapped from outside (cyber security).
* Direct integration of external modules (e.g., in docking mechanisms, as described in [10]) without optical-electrical conversion.  
In this paper, a first prototype of a LiFi-transceiver module is presented, which is tailored for intra-satellite communications for reliable TMTC communication. The primary requirements were the miniaturization of the module, reliability and energy efficiency of the communication. The conceptual design of a transceiver is presented. The suitability of a TIA for the reception of LiFi signals is simulated and evaluated in laboratory tests. Furthermore, the data transmission is secured by different Error-Correcting-Codes (ECCs). The results show that LiFi transceivers can be implemented in a highly miniaturized form and that data transmission of up to 94.3 kbit/s (no coding)/77.6 kbit/s (Reed-Solomon) is possible, which is already suitable for the transmission of TMTC in satellites.