Probabilistic amplitude shaping (PAS) has proved to be a promising way to achieve the shaping gain for an additive white Gaussian noise channel with a distribution matcher (DM). However, the DM schemes may suffer a rate loss and increase both complexity and latency, when they are not suited for the input bit stream with redundancy. In this paper, a novel PAS strategy is proposed for a joint source and channel coded modulation system, where the residual source redundancy after source coding can be exploited to obtain both shaping and coding gains. It is shown that the residual source redundancy can be controlled by choosing the row weight distribution for source code, thus making the probability distribution of the modulated symbols be optimized under an appropriate interleaver design. To guarantee the error-floor performance, the source code is constrained by predicting the probability distribution of source bits within target finite-length frames. By jointly designing source and channel codes, the residual source redundancy can also be exploited to achieve the coding gain. Compared with the state-of-the-art code pairs, the proposed code pairs have better error-floor performance, and achieve higher coding and shaping gains without suffering from the rate-loss and the latency caused by DM.

中文翻译：

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基于剩余源冗余的 Protograph LDPC 编码调制的概率整形

概率幅度整形 (PAS) 已被证明是使用分布匹配器 (DM) 实现加性高斯白噪声通道整形增益的一种很有前景的方法。然而，当 DM 方案不适合具有冗余的输入比特流时，它们可能会遭受速率损失并增加复杂性和延迟。在本文中，针对联合源和信道编码调制系统提出了一种新的 PAS 策略，其中可以利用源编码后的剩余源冗余来获得整形和编码增益。结果表明，可以通过选择源代码的行权重分布来控制残余源冗余，从而在适当的交织器设计下优化调制符号的概率分布。为保证error-floor性能，通过预测目标有限长度帧内源位的概率分布来约束源代码。通过联合设计源代码和信道代码，还可以利用剩余的源冗余来实现编码增益。与最先进的码对相比，所提出的码对具有更好的误码性能，并在不遭受 DM 引起的速率损失和延迟的情况下实现更高的编码和整形增益。