  Rate-Splitting Multiple Access (RSMA) is an emerging flexible and powerful
multiple access for downlink multiantenna networks. In this paper, we introduce
the concept of RSMA into short-packet downlink communications. We design
optimal linear precoders that maximize the sum rate with Finite Blocklength
(FBL) constraints. The relations between the sum rate and blocklength of RSMA
are investigated for a wide range of network loads and user deployments.
Numerical results demonstrate that RSMA can achieve the same transmission rate
as Non-Orthogonal Multiple Access (NOMA) and Space Division Multiple Access
(SDMA) with shorter blocklengths (and therefore lower latency), especially in
overloaded multi-antenna networks. Hence, we conclude that RSMA is a promising
multiple access for low-latency communications.
