Enabled by hybrid grant-based (GB) and grant-free (GF) transmission techniques, GF users of internet of things (IoT) devices and massive machine-type communications (mMTC) meet opportunities to share wireless resources with GB users. In this paper, we propose a rate splitting multiple access (RSMA) strategy for an emerging semi-grant-free (SGF) transmission system to increase connectivity and reliability. In the proposed RSMA assisted SGF (RSMA-SGF) scheme, the GF users apply the rate splitting principle to realize distributed contentions and utilize transmit power most effectively for robust transmissions, meanwhile keeping themselves transparent to the GB user. Compared to existing non-orthogonal multiple access (NOMA) assisted SGF schemes, the RSMA-SGF scheme significantly decreases outage probability and achieves full multiuser diversity gain without restricting the GB and GF users' target rates to a limited value region. Exact expressions and asymptotic analysis for the outage probability are provided to facilitate the system performance evaluation of the proposed RSMA-SGF scheme. Computer simulation results clarify the superior outage performance of the RSMA-SGF scheme and verify the accuracy of the developed analytical results.
翻译:通过混合赠款和无赠款传输技术的混合赠款(GB)和无赠款(GF)传输技术,商品互联网(IoT)装置和大规模机器型通信的GF用户有机会与GB用户分享无线资源。在本文件中,我们提议为新兴的半赠款(SGF)传输系统采用分率多重接入战略,以提高连通性和可靠性。在拟议的RSMA协助的SGF(RSMA-SGF)计划中,GF用户采用分率原则,实现分布式争议,最有效地传输权力,同时保持其与GB用户的透明。与现有的非横向多重接入(NOMA)协助的SGF计划相比,RSMA-SG计划大幅降低外向概率,在不将GB和GF用户的目标率限制在有限价值区域的情况下实现完全的多用户多样性。提供了对外向概率的速率分析分析,以方便对拟议的RSMA-S-SGF计划进行系统业绩评价。计算机模拟的结果澄清了RSMA-GF的高级外向结果。