In an unsourced random access (URA) [1] scenario, multiple users transmit information over the same channel, and a decoder at the receiver must attempt to recover the set of sent messages from the received sum.

Sum-free sets are sets for which the sum of any two elements is not contained in the set itself. Bh[g] sets [2] are sets for which every element can be written in at most g different ways as the sum of h elements.

Both of these kinds of sets might be interesting for use as codebooks in the URA scenario, as they give additional information about the elements (messages) that may be contained in a sum (received word).

The student is expected to produce an overview over existing literature on sum-free and Bh[g] sets, and to relate this to coding for the URA scenario.

[1] Unsourced Random Access: A Comprehensive Survey

[2] Recent Progress on Finite Bh[g] Sets

In an unsourced random access scenario, multiple users communicate over the same channel. The receiver receives the sum of the sent signals, and from this attempts to retrieve the set of sent messages.

Tensor-based schemes approach this problem by representing sent messages as tensors, and attempt to retrieve them through tensor decomposition.

The student should understand this tensor-based approach, give an overview over existing tensor-based random access schemes, and compare different approaches, using the overview given in Section III.V.D.2 of [1] as a starting point.

[1] Unsourced Random Access: A Comprehensive Suvey

Voraussetzungen