Rate-splitting multiple access (RSMA) has attracted a lot of attention as a
general and powerful multiple access scheme. In the uplink, instead of encoding
the whole message into one stream, a user can split its message into two parts
and encode them into two streams before transmitting a superposition of these
two streams. The base station (BS) uses successive interference cancellation
(SIC) to decode the streams and reconstruct the original messages. Focusing on
the packet transmission reliability, we investigate the features of RSMA in the
context of hybrid automatic repeat request (HARQ), a well-established mechanism
for enhancing reliability. This work proposes a HARQ scheme for uplink RSMA
with different retransmission times for a two-user scenario and introduces a
power allocation strategy for the two split streams. The results show that
compared with non-orthogonal multiple access (NOMA) and frequency division
multiple access (FDMA), RSMA outperforms them in terms of error probability and
power consumption. The results show that RSMA with HARQ has the potential to
improve the reliability and efficiency of wireless communication systems