An Efficient Grant-Based Scheme for the Massive Random Access Gaussian Channel

Abstract

This paper investigates the massive random access Gaussian channel with a focus on small payloads.For this problem, grant-based schemes have been regarded as inefficient due to the necessity of large feedbacks and the use of inefficient scheduling request methods. In this paper, a novel grant-based scheme is proposed, which appears to outperform previous methods. The scheme uses Ordentlich and Polyanskiy's grantless method to transmit small coordination indices in order to perform the scheduling request, which allows both the request from the users to be efficient and the feedback to be small. We also present an improvement to the Ordentlich and Polyanskiy's scheme, allowing it to handle collisions of the same message, significantly improving the method for very small messages. Simulation results show that, if a short feedback is allowed, our method requires lower energy per bit than existing practical grantless methods.