We propose guessing random additive noise decoding-aided macrosymbols (GRAND-AMs) as a nonorthogonal multiple access (NOMA) method that can detect, error correct, and decode multiple users with imperfect channel estimation, asynchronous transmission, and interference, which are all topics of concern for Internet of Things. GRAND-AM is a NOMA method that uses both joint multiuser detection and joint error correction decoding to handle multiple access interference (MAI). For the joint multiuser detector, we introduce the concept of a macrosymbol, which is constructed from the combination of all user symbols. For the error correction decoding component, we introduce multiple access channel (MAC) codes, which are codes that are used to split the channel rate between users and correct errors due to MAI. In this scheme, each user has their information bits encoded with independent MAC codes. We use a soft detection variant of GRAND, an efficient and practical decoding method that inverts noise effect sequences from a sequence of symbols to arrive at a codeword, to correct a sequence of macrosymbols, ensuring that all user codebooks are simultaneously satisfied. The joint detection and decoding of GRAND-AM can outperform time division multiple access (TDMA) by 10 dB with perfect channel estimation, and by 6 dB with imperfect channel estimation. Considering a more complete communication chain, when additional forward error correction is used along with the MAC code, the GRAND-AM method performs similarly to a same rate low-density parity-check-coded TDMA system.

中文翻译：

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具有猜测随机加性噪声解码辅助宏符号的非正交多址接入 (GRAND-AM)


我们提出猜测随机加性噪声解码辅助宏符号（GRAND-AM）作为一种非正交多址（NOMA）方法，可以在不完善的信道估计、异步传输和干扰的情况下检测、纠错和解码多个用户，这些都是主题对物联网的关注。 GRAND-AM 是一种 NOMA 方法，它使用联合多用户检测和联合纠错解码来处理多址干扰 (MAI)。对于联合多用户检测器，我们引入了宏符号的概念，它是由所有用户符号的组合构造的。对于纠错解码组件，我们引入了多址信道（MAC）代码，这些代码用于在用户之间分割信道速率并纠正由于 MAI 导致的错误。在该方案中，每个用户的信息比特都用独立的MAC代码进行编码。我们使用GRAND的软检测变体，这是一种高效实用的解码方法，可将噪声影响序列从符号序列反转到码字，以纠正宏符号序列，确保同时满足所有用户码本。 GRAND-AM 的联合检测和解码在完美信道估计的情况下比时分多址 (TDMA) 性能高 10 dB，在不完美信道估计的情况下比时分多址 (TDMA) 性能高 6 dB。考虑到更完整的通信链，当附加前向纠错与MAC码一起使用时，GRAND-AM方法的性能类似于相同速率的低密度奇偶校验编码TDMA系统。