On Frame Asynchronous Coded Slotted ALOHA: Asymptotic, Finite Length, and Delay Analysis
Journal article, 2017

We consider a frame asynchronous coded slotted ALOHA (FA-CSA) system for uncoordinated multiple access, where users join the system on a slot-by-slot basis according to a Poisson random process and, in contrast to standard frame synchronous CSA (FS-CSA), users are not frame-synchronized. We analyze the performance of FA-CSA in terms of packet loss rate and delay. In particular, we derive the (approximate) density evolution that characterizes the asymptotic performance of FACSA when the frame length goes to infinity. We show that, if the receiver can monitor the system before anyone starts transmitting, a boundary effect similar to that of spatially-coupled codes occurs, which greatly improves the iterative decoding threshold. Furthermore, we derive tight approximations of the error floor (EF) for the finite frame length regime, based on the probability of occurrence of the most frequent stopping sets. We show that, in general, FA-CSA provides better performance in both the EF and waterfall regions as compared to FS-CSA. Moreover, FACSA exhibits better delay properties than FS-CSA.

uncoordinated multiple access

density evolution

frame asynchronous

random access

spatially coupled codes

Coded slotted ALOHA

finite length analysis

error floor

packet loss rate

Author

Erik Sandgren

Chalmers, Signals and Systems

Alexandre Graell i Amat

Chalmers, Signals and Systems, Kommunikationssystem, informationsteori och antenner, Communication Systems

Fredrik Brännström

Chalmers, Signals and Systems, Kommunikationssystem, informationsteori och antenner, Communication Systems

IEEE Transactions on Communications

0090-6778 (ISSN)

Vol. 65 691-704 7762138

Areas of Advance

Information and Communication Technology

Subject Categories

Telecommunications

Communication Systems

DOI

10.1109/TCOMM.2016.2633468