Faster-than-Nyquist (FTN) signaling is a nonorthogonal transmission technique, which brings in intentional inter-symbol interference. This way it can significantly enhance spectral efficiency for practical pulse shapes such as the root raised cosine pulses. This paper proposes an achievable rate region for the multiple antenna (MIMO) asynchronous multiple access channel (aMAC) with FTN signaling. The scheme applies waterfilling in the spatial domain and precoding in time. Waterfilling in space provides better power allocation and precoding helps mitigate inter-symbol interference due to asynchronous transmission and FTN. The results show that the gains due to asynchronous transmission and FTN are more emphasized in MIMO aMAC than in single antenna aMAC. Moreover, FTN improves single-user rates, and asynchronous transmission improves the sum-rate, due to better inter-user interference management.

翻译：超奈奎斯特（FTN）信令是一种非正交传输技术，会引入人为的码间干扰。对于根升余弦脉冲等实际脉冲成形，该技术能显著提升频谱效率。本文提出了采用FTN信令的多天线（MIMO）异步多址接入信道（aMAC）的可达速率域。该方案在空间域采用注水算法，在时间域采用预编码技术。空间域注水算法可优化功率分配，而预编码有助于缓解异步传输和FTN导致的码间干扰。结果表明，与单天线aMAC相比，MIMO aMAC中异步传输和FTN带来的增益更为显著。此外，FTN可提升单用户速率，异步传输则通过改善用户间干扰管理来提高总速率。