Enhanced MAC Protocol with New Packing for Imagery Transmission in Link-16

Link-16 is a widely used Tactical Data Link (TDL) system and a very low rate system, thus, it supports transmission of limited data such as text-based tactical messages and voice. Recently, in order to support large amounts of data such as imagery, there have been several studies focusing on increasing the data rate of Link-16 by modifying the waveform. However, efforts to reduce the effect of a large propagation delay are also required, as a time slot in Link-16 includes a large waste of guard time. In particular, the transmission of imagery, which requires a number of time slots, is significantly affected by the guard time. Moreover, Link-16 uses a donated slot for acknowledgment (ACK) of one message. Thus, it causes large overhead when the imagery requires many time slots. In this paper, we propose an enhanced MAC protocol with a new packing type to improve the performance of Link-16 by reducing the effect of a large propagation delay and the overhead of ACK. In the protocol, time slots are allocated on the basis of the proposed Available Time Slot (ATS) selection, not on the Recurrence Rate Number (RRN) of Link-16. Thus, there may be successive time slots in which the proposed packing type can be used for transmitting more bits by reusing the guard time. Moreover, the protocol provides retransmission on the basis of Block Negative ACK (BNACK). Thus, the number of time slots required for ACK can be reduced, and the delay for retransmission is greatly decreased. Simulation results show that the proposed protocol with a new packing type can improve the performance of Link-16.