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IEICE TRANSACTIONS on Communications

Open Access
HARQ Using Hierarchical Tree-Structured Random Access Identifiers in NOMA-Based Random Access

Megumi ASADA, Nobuhide NONAKA, Kenichi HIGUCHI

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Summary :

We propose an efficient hybrid automatic repeat request (HARQ) method that simultaneously achieves packet combining and resolution of the collisions of random access identifiers (RAIDs) during retransmission in a non-orthogonal multiple access (NOMA)-based random access system. Here, the RAID functions as a separator for simultaneously received packets that use the same channel in NOMA. An example of this is a scrambling code used in 4G and 5G systems. Since users independently select a RAID from the candidate set prepared by the system, the decoding of received packets fails when multiple users select the same RAID. Random RAID reselection by each user when attempting retransmission can resolve a RAID collision; however, packet combining between the previous and retransmitted packets is not possible in this case because the base station receiver does not know the relationship between the RAID of the previously transmitted packet and that of the retransmitted packet. To address this problem, we propose a HARQ method that employs novel hierarchical tree-structured RAID groups in which the RAID for the previous packet transmission has a one-to-one relationship with the set of RAIDs for retransmission. The proposed method resolves RAID collisions at retransmission by randomly reselecting for each user a RAID from the dedicated RAID set from the previous transmission. Since the relationship between the RAIDs at the previous transmission and retransmission is known at the base station, packet combining is achieved simultaneously. Computer simulation results show the effectiveness of the proposed method.

Publication
IEICE TRANSACTIONS on Communications Vol.E106-B No.8 pp.696-704
Publication Date
2023/08/01
Publicized
2023/02/21
Online ISSN
1745-1345
DOI
10.1587/transcom.2023EBP3001
Type of Manuscript
PAPER
Category
Wireless Communication Technologies

Authors

Megumi ASADA
  Tokyo University of Science
Nobuhide NONAKA
  NTT DOCOMO, INC.
Kenichi HIGUCHI
  Tokyo University of Science

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