Teletraffic analysis and simulation on FSO systems: the traffic generators approach

Abstract

Free Space Optical Communications (FSO) has become an interesting topic to researchers in recent years since the amount of data generated by devices is growing, and it is necessary to use data links that support high bandwidth to transmit them from one device to another. This technology is used to establish not only terrestrial links but also space links. A CubeSat satellite is generally deployed in the Low Earth Orbit (LEO) region. To maintain the altitude, the satellite must have a high orbital speed. For that reason, the time to transmit data between a particular ground station and the CubeSat satellite is limited. On the other hand, the volume, mass, and energy storage capacity are restricted in a CubeSat. The greater the bandwidth capacity of radio frequency links, the greater the demand for volume, mass, and energy they require. For that reason, to transmit a significant amount of data, traditional radio frequency links are not suitable and are becoming replaced by FSO as technology improves. Despite research in physical layer technologies on FSO (modulation schemes, error mitigation techniques, pointing and tracking systems), there is very little research in the literature about data link layer protocols for FSO. Secondly, there is little research to measure the data traffic demand on CubeSat satellites so that a certain data link layer protocol can be selected or adapted to be implemented in an FSO system. This paper presents research to address the issue of teletraffic through the use of traffic generators. The result is the design and development of a traffic generator for a discrete event simulator that will later be used to observe the behavior and to measure the performance of the Selective Repeat ARQ protocol in a simulated satellite FSO link, in order to propose improvements to adapt the protocol to this scenario.