Code-expanded Random Access (CeRA) is a promising technique for supporting massive machine-type communications in cellular IoT networks. However, its potentiality is limited by code ambiguity, which results from the inference of a larger number of codewords than those actually transmitted. In this letter, we propose a random access (RA) scheme to alleviate this problem by allowing devices to select the preambles to be transmitted considering a ${q}$ -ary code with maximum average distance. Moreover, a CeRA decoding approach based on hypergraphs is proposed and an analytical model is derived. Numerical results show that the proposed scheme significantly increases the probability of successful channel access as well as resource utilization.

中文翻译：

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基于最大平均距离码的蜂窝物联网海量MTC随机接入

代码扩展随机访问 (CeRA) 是一种很有前途的技术，用于支持蜂窝物联网网络中的大规模机器类型通信。然而，它的潜力受到代码歧义的限制，这是由于推断出的代码字比实际传输的代码字多。在这封信中，我们提出了一种随机接入 (RA) 方案，以通过允许设备选择要传输的前导码来缓解这个问题。 ${q}$ 具有最大平均距离的 -ary 代码。此外，提出了一种基于超图的CeRA解码方法，并推导出了分析模型。数值结果表明，所提出的方案显着提高了成功信道接入的概率以及资源利用率。