## 1 Introduction  
To accomplish flexible and rapid response tactical missions, the Operationally Responsive Space (ORS) was proposed by the United States Department of Defense (DoD) [1]. Through the implementation of the launch-on-demand of dedicated platforms, the ORS system provides rapid, flexible and economic access to future space missions, including tracking, data relay and Earth observation [2]. To deploy various types of tasks, a common interface is required for integrating different satellite payloads and subsystems [3]. As the main technical verification project of the ORS, the TacSat plan aims to build a standardized bus and achieve rapid spacecraft design. Since 2006, dozens of satellites have been launched successfully [4; 5; 6; 7; 8; 9]. Likewise, in China, two mapping satellites, Kuaizhou-1 (KZ-1) and Kuaizhou-2 (KZ-2), have been developed. The missions aim to provide information support for rapid-response land observation, including emergency monitoring and disaster relief [10; 11]. The rapid ground integration, assembly and test (AIT) of satellites are significantly crucial yet very challenging in developing an ORS system. Besides, the miniaturization and reliability of such systems are in high demand. In the past decades, with the rapid development of integrated electronic technology, both harness reduction and reliability improvements were accomplished. However,previous studies have shown that cables, interfacing hardware and connectors account for 7-10% of the mass of a satellite, half of which are data transfer cables [12; 13]. It has also been revealed that these interdependent physical links tend to increase the redundancy of a satellite, which, in turn, decreases the reliability of the satellites. These issues have been a major obstacle that has hindered the miniaturization and rapid design of ORS satellites [14; 15]. Wireless buses and interfaces have been considered as promising alternatives to solve the abovementioned problem. They allow one to eliminate the cables so that both the data rate and reliability of the intra-satellite network can be improved [12; 16]. Among many wireless technologies, Optical Wireless (infrared-IR) and Radio Frequency (RF) are leading candidates. Proposed by National Institute for Aerospace Technique of Spain (INTA), the Optical Wireless Links for intra-Spacecraft communications (OWLS) approach has been studied by many groups in the past decades [17; 18]. OWLS offers a direct access to high data rate long range communication without any electromagnetic interference/compatibility (EMI/EMC) concerns [18]. However, for optical wireless interfaces, line-of-sight (LOS) communication requires a clear signal path, which imposes limitations on the layout design of satellite cabins. In another case, the diffuse communication will result in a short range and unguided transmission. In addition, according to the CCSDS and other previous studies [19; 20], the optical link for intra-spacecraft communications can be easily shielded too. In contrast, the Radio Frequency (RF) technology is more mature, and it also has better penetration and simpler components. It provides a high data rate without direct LOS. To put it simply, RF wireless interfaces is are flexible, and can be easily monitored. They can effectively simplify and shorten the AIT process of the satellite design. In recent years, RF has therefore been introduced to intra-satellite communication. At Delft University and Surrey University, Zigbee and Bluetooth were directly applied to satellite on-board wireless protocol design [12; 21; 22; 23; 24; 25], including a wireless digital Sun sensor [23], an EADS micropack wireless temperature transducer [24] and a wireless satellite Delfi-C3 [25]. In Spain, a Zigbee-based hardware architecture for intra-satellite communication was proposed, and its robustness to the space electromagnetic environment was discussed [8].