Judicious use of redundant transmissions in multichannel ALOHAnetworks with deadlines

摘要

This paper shows how to improve the classic multichannel slottednALOHA protocols by judiciously using redundant transmissions. The focusnis on user-oriented requirements: a deadline along with a permissiblenprobability of failing to meet it. Subject to satisfying those,nmaximization of capacity is the optimization goal. When there is nonsuccess/failure feedback prior to the deadline, the use of informationndispersal with some redundancy provided by error-correcting codes fornthe data in conjunction with a replicated, separately transmittednsynchronization preamble, is proposed. It is shown to sharply reduce thenoverhead resulting from the use of shorter packets and to significantlynincrease the capacity. When the deadline permits severalntransmission-feedback rounds, we propose a novel replication-basednretransmission policy: all attempts except the final one entail thentransmission of a single or very few copies, and a larger number ofncopies are transmitted in the final attempt. This sharply increasesnchannel capacity, even with a single transmitter per station. Thenproposed approaches are particularly suitable for high-bandwidthnsatellites with on-board processing