Coding-Based Slotted ALOHA for Broadcasting Multislot Messages With Delivery Deadline

Coding-based slotted ALOHA is one effective way to guarantee communication reliability for multislot messages when the acknowledgment mechanism is difficult to use. Prior to the transmission of an m-slot message, n single-slot coded packets are constructed using erasure-correcting codes, such that any m successfully received coded packets can yield a correct reception of the message. This paper considers the codingbased slotted ALOHA for one-hop broadcasting with delivery deadline D (in unit of slot), which requires every message to be sent out within the deadline since its arrival on the head of the queue. We derive exact closed-form expressions for important performance metrics for any 1 ≤ m ≤ n ≤ D. In particular, a simple closed-form suboptimal transmission probability for the reliability maximization is then heuristically proposed, and moreover, the minimum value of n under reliability constraint is investigated.