3 research outputs found
The Strongly Asynchronous Massive Access Channel
This paper considers a Strongly Asynchronous and Slotted Massive Access
Channel (SAS-MAC) where different users transmit a randomly
selected message among ones within a strong asynchronous window
of length blocks, where each block lasts 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 , 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
Capacity per Unit-Energy of Gaussian Random Many-Access Channels
We consider a Gaussian multiple-access channel with random user activity
where the total number of users and the average number of active users
may be unbounded. For this channel, we characterize the maximum number of
bits that can be transmitted reliably per unit-energy in terms of and
. We show that if is sublinear in , then each user can
achieve the single-user capacity per unit-energy. Conversely, if is superlinear in , then the capacity per unit-energy is zero. We
further demonstrate that orthogonal-access schemes, which are optimal when all
users are active with probability one, can be strictly suboptimal.Comment: Presented in part at the IEEE International Symposium on Information
Theory (ISIT) 202
The Strongly Asynchronous Massive Access Channel
This paper considers the Strongly Asynchronous, Slotted, Discrete Memoryless, Massive Access Channel (SAS-DM-MAC) in which the number of users, the number of messages, and the asynchronous window length grow exponentially with the coding blocklength with their respective exponents. A joint 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, 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. It is shown that reliable transmission with an exponential number of users with an exponential asynchronous exponent with joint error probability is possible at strictly positive rates