We introduce a new grant-free non-orthogonal multiple access (GF-NOMA) scheme, which unlike conventional approaches, spreads over the frequency domain instead of the time domain to reduce access latency. Most conventional receivers for GF-NOMA require the pre-tuning of hyperparameters to achieve superior performance. To avoid such pre-tuning, we propose a hyperparameter-free receiver for the proposed architecture, exploiting the sparsity of channels in the delay domain. Simulation results demonstrate the superior performance of the proposed receiver in terms of the normalized mean-squared error and the activity error rate.

中文翻译：

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带有MIMO-OFDM的免授权NOMA系统的超参数无接收器

我们引入了一种新的免授权非正交多址访问（GF-NOMA）方案，该方案与传统方法不同，它在频域而不是时域上扩展，以减少访问延迟。GF-NOMA的大多数常规接收器都需要对超参数进行预调节才能获得出色的性能。为了避免这种预调谐，我们为所提出的体系结构提出了一种无超参数的接收器，它利用了延迟域中信道的稀疏性。仿真结果证明了所提出的接收器在归一化均方误差和活动误差率方面的优越性能。