Doppler based multiple access (DBMA): a novel flow control mechanism for LEO satellite systems

The problem of flow control for little LEO satellite communication systems is studied. In these systems the satellites functions as a "bent pipe" transponder for messaging between small terminals (tags) and a control and data acquisition (CDA) Earth station. A novel scheme for averting traffic overflow on the in-bound channel (from tag to CDA), which we call "Doppler based multiple access (DBMA)", is introduced. In DBMA, the CDA specifies a subset of the visibility footprint as a region of eligibility (ROE). Only tags located in the ROE are permitted to transmit. By varying the area and location of the ROE, effective flow control is achieved on the inbound channel. The ROEs are specified in terms of parameters of the Doppler S-curve observed at tags on the outbound channel. The effectiveness and elegance of DBMA protocol are illustrated through computer simulations.