A Remark on Downlink Massive Random Access
This reduces communication overhead for base stations in massive random access scenarios, but it is incremental as it builds on existing combinatorial insights.
The paper tackles the overhead problem in downlink massive random access by showing that deterministic variable-length codes can achieve an overhead no greater than 1 + log2 e bits, improving upon prior bounds.
In downlink massive random access (DMRA), a base station transmits messages to a typically small subset of active users, selected randomly from a massive number of total users. Explicitly encoding the identities of active users would incur a significant overhead scaling logarithmically with the number of total users. Recently, via a random coding argument, Song, Attiah and Yu have shown that the overhead can be reduced to within some upper bound irrespective of the number of total users. In this remark, recognizing that the code design for DMRA is an instance of covering arrays in combinatorics, we show that there exists deterministic construction of variable-length codes that incur an overhead no greater than $1 + log_2 e$ bits.