| Popis: |
Performance instabilities due to the fading are vital subjects for long distance free space optical communication systems in which the signal lights travel through the atmosphere. The straightforward approach is to introduce the combinations of optical transmitters and receivers that can operate in various modulation speeds, and the operator selects the speed from the candidates in order to manipulate photons per bit according to the link conditions. However, the realization of such functions with single hardware may result in the halfway capabilities. For these problems, our group has been proposing the use of the technologies that we call Adaptive Distributed Frame Repetition (ADFR), in which a high-speed link is divided in time, and sending node replicates frames and transmits over a single link with the proper time intervals without concerning whether each frame arrives at the destination or not. Since the line rate is always constant, and functions equipped in the receiving node are simple, settings at the transmitting node relating to retransmission can be switched seamlessly without any negotiations with the opposite. In this time, the main functions of ADFR are implemented on the computers to be experimentally evaluated at 10 Gbps. In addition to the basic results about static and dynamic performances of ADFR, the combined performance with TCP assumed to be introduced in the GEO-Ground system will be discussed in the paper. |
