The Strongly Asynchronous Massive Access Channel

This paper considers a Strongly Asynchronous and Slotted Massive Access Channel (SAS-MAC) where $K_n:=e^{n\nu}$ different users transmit a randomly selected message among $M_n:=e^{nR}$ ones within a strong asynchronous window of length $A_n:=e^{n\alpha}$ blocks, where each block lasts $n$ channel uses. A global probability of error is enforced, ensuring that all the users' identities and messages are correctly identified and decoded. Achievability bounds are derived for the case that different users have similar channels, the case that users' channels can be chosen from a set which has polynomially many elements in the blocklength $n$, and the case with no restriction on the users' channels. A general converse bound on the capacity region and a converse bound on the maximum growth rate of the number of users are derived.Comment: under submissio

On the Capacity of the Slotted Strongly Asynchronous Channel with a Bursty User

The slotted strongly asynchronous channel with a bursty user consists of a window of An = enα blocks of length n channel uses. A user transmits a randomly selected message among Mn = enR different ones in exactly Kn = env randomly selected but distinct blocks in the window. The receiver must locate and decode, with vanishing error probability in n, each one of the transmitted messages. The optimal tradeoff between (R, α, ν) is derived