Efficient OFDM Mobile Radio Packet System Employing LLR Combining Multiuser Detection for ARQ with Adaptive Modulation and Coding Scheme

• NAGAREDA Riichiro

  Tokyo Institute of Technology

• FUKAWA Kazuhiko

  Tokyo Institute of Technology

• SUZUKI Hiroshi

  Tokyo Institute of Technology

Abstract

This paper proposes an OFDM mobile radio packet system that employs a new protocol of automatic repeat request (ARQ) for nonlinear multiuser detection (MUD) with log likelihood ratio combining (LC) on the appropriate bits. The conventional metric combining (MC) MUD separates collided packets by using nonlinear MUD, accumulates the Euclidian distance metrics of the received subcarrier symbols in the packets, and then achieves throughput improvement. However, when MC-MUD detects a packet error, it makes user terminals retransmit the same packets so as to reproduce the collision of the same packets. The proposed LC-MUD scheme simplifies the ARQ protocol and requires no reproduction of the same packet collision. The computer simulations demonstrate the superior throughput of LC-MUD to that of MC-MUD, and further improvement due to adaptive modulation and coding (AMC) optimized for the nonlinear MUD in LC-MUD.

Journal

• IEICE Trans. on Commun., B

  IEICE Trans. on Commun., B 90 (6), 1444-1453, 2007-06-01

  The Institute of Electronics, Information and Communication Engineers

Keywords

• OFDM
• mobile radio packet
• multiuser detection
• ARQ
• metric combining
• LLR
• adaptive modulation and coding

Details

• CRID: 1571417127485622912
• NII Article ID: 110007519410
• NII Book ID: AA10826261
• ISSN: 09168516
• Text Lang: en
• Data Source:
  • CiNii Articles