In this paper, we propose an interference exploitation symbol-level precoding (SLP) method for multi-level modulations via an in-block power allocation scheme to greatly reduce the signaling overhead. Existing SLP approaches require the symbol-level broadcast of the rescaling factor to the users for correct demodulation, which hinders the practical implementation of SLP. The proposed approach allows a block-level broadcast of the rescaling factor as done in traditional block-level precoding, greatly reducing the signaling overhead for SLP without sacrificing the performance. Our derivations further show that the proposed in-block power allocation enjoys an exact closed-form solution and thus does not increase the complexity at the base station (BS). In addition to the significant alleviation of the signaling overhead validated by the effective throughput result, numerical results demonstrate that the proposed power allocation approach also improves the error-rate performance of the existing SLP. Accordingly, the proposed approach enables the practical use of SLP in multi-level modulations.

翻译：在本文中,我们建议通过区块内电力分配办法,对多级调制器采用干扰符号预编码法(SLP),以大幅降低信号管理费用;现有的SLP办法要求向用户进行代号级的调整因数广播,以正确降压,这妨碍了SLP的实际实施。提议的办法允许像传统的区块预编码那样,对调制因数进行区块级广播,大大降低SLP的信号管理费用,同时又不牺牲性能。我们的推算进一步表明,拟议的区块电力分配办法具有精确的封闭式解决办法,因此不会增加基地站的复杂程度。除了大幅减轻有效吞吐结果所验证的信号性管理费用外,数字结果表明,拟议的电力分配办法还提高了现有SLP的误率性能。因此,拟议的办法使SLP在多级调制中能够实际使用。