Recently, the use of intelligent reflecting surface (IRS) has gained considerable attention in wireless communications. By intelligently adjusting the passive reflection angle, IRS is able to assist the base station (BS) to extend the coverage and improve spectral efficiency. This paper considers a joint symbol-level precoding (SLP) and IRS reflecting design to minimize the symbol-error probability (SEP) of the intended users in an IRS-aided multiuser MISO downlink. We formulate the SEP minimization problems to pursue uniformly good performance for all users for both QAM and PSK constellations. The resulting problem is non-convex and we resort to alternating minimization to obtain a stationary solution. Simulation results demonstrate that under the aid of IRS our proposed design indeed enhances the bit-error rate performance. In particular, the performance improvement is significant when the number of IRS elements is large.

中文翻译：

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具有智能反射面的最小符号错误概率符号级预编码

最近，智能反射面（IRS）的使用在无线通信中得到了相当大的关注。通过智能调整无源反射角，IRS能够辅助基站（BS）扩大覆盖范围，提高频谱效率。本文考虑了联合符号级预编码 (SLP) 和 IRS 反射设计，以最小化 IRS 辅助多用户 MISO 下行链路中预期用户的符号错误概率 (SEP)。我们制定了 SEP 最小化问题，以便为 QAM 和 PSK 星座的所有用户追求一致的良好性能。由此产生的问题是非凸的，我们采用交替最小化来获得平稳解。仿真结果表明，在 IRS 的帮助下，我们提出的设计确实提高了误码率性能。特别是，