Abstract
Non-orthogonal multiple access schemes with grant free access have been recently highlighted as a prominent solution to meet the stringent requirements of massive machine-type communications (mMTCs). In particular, the multi-user shared access (MUSA) scheme has shown great potential to grant free access to the available resources. For the sake of simplicity, MUSA is generally conducted with the successive interference cancellation (SIC) receiver, which offers a low decoding complexity. However, this family of receivers requires sufficiently diversified received user powers in order to ensure the best performance and avoid the error propagation phenomenon. The power allocation has been considered as a complicated issue especially for a decentralized decision with a minimum signaling overhead. In this paper, we propose a novel algorithm for an autonomous power decision with a minimal overhead based on a tight approximation of the bit error probability (BEP) while considering the error propagation phenomenon. We investigate the efficiency of multi-armed bandit (MAB) approaches for this problem in two different reward scenarios: (i) in Scenario 1, each user reward only informs about whether its own packet was successfully transmitted or not; (ii) in Scenario 2, each user reward may carry information about the other interfering user packets. The performances of the proposed algorithm and the MAB techniques are compared in terms of the successful transmission rate. The simulation results prove that the MAB algorithms show a better performance in the second scenario compared to the first one. However, in both scenarios, the proposed algorithm outperforms the MAB techniques with a lower complexity at user equipment.
Highlights
Published: 27 December 2020The future radio access network of the fifth-generation is expected to support a variety of applications with different qualities of service (QoSs)
The conventional orthogonal multiple access (OMA) schemes are limited by the restricted number of available orthogonal resources, and thereby, they may not be suitable to handle the huge number of devices to be connected in the massive machine-type communications (mMTCs) scenario
We address this issue by proposing a novel algorithm for autonomous power decision based on the proposed bit error probability (BEP)
Summary
The future radio access network of the fifth-generation is expected to support a variety of applications with different qualities of service (QoSs). One problem of grant free access is the estimation of the number of active users This issue was addressed in [12] by proposing a deep learning algorithm, which uses the recorded user activities at the base station to predict their future behavior. The authors in [22] applied the MAB algorithms to the autonomous power decision problem in order to maximize the user rates for the PD-NOMA scheme. The goal is to improve the system performance measured with the successful transmission rate in order to achieve the performance of an optimal centralized power allocation The latter is quite difficult to obtain, especially for SIC receivers with the error propagation problem. (.) T and (.) H stand for the transpose and Hermitian operations. diag(a) represents the diagonal matrix created with the elements of vector a in the main diagonal
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