Opportunistic Multiuser Two-Way Amplify-And-Forward Relaying with a Multiantenna Relay

Duckdong Hwang, Bruno Clerckx, Sung Sik Nam, Tae Jin Lee

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


We consider the opportunistic multiuser diversity in the multiuser two-way amplify-And-forward (AF) relay channel. The relay, which is equipped with multiple antennas and a simple zero-forcing beamforming (ZFBF) scheme, selects a set of two way relaying user pairs to enhance the degree of freedom (DoF) and, consequently, the sum throughput of the system. The proposed channel-Aligned pair scheduling (CAPS) algorithm reduces the interpair interference and keeps the signal-To-interference-plus-noise-power ratio (SINR) of user pairs that are interference-free when the number of user pairs becomes very large. When the number of user pairs grows fast enough with the system signal-To-noise ratio (SNR), a DoF equal to the number of relay antennas can be achieved. For a realistic number of user pairs, we propose an adaptive CAPS and an adaptive semi-orthogonal CAPS (SCAPS) to improve performance. Simulation results show that adaptive CAPS and adaptive SCAPS provide throughput gain in the low-To-mid SNR region.

Original languageEnglish
Article number7120995
Pages (from-to)3777-3782
Number of pages6
JournalIEEE Transactions on Vehicular Technology
Issue number5
Publication statusPublished - 2016 May

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea funded by the Korean Ministry of Science, ICT, and Future Planning under Grant 2014R1A5A1011478.

Publisher Copyright:
© 1967-2012 IEEE.


  • Two-way relaying
  • amplify and forward
  • degree of freedom
  • opportunistic user pair selection

ASJC Scopus subject areas

  • Automotive Engineering
  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Applied Mathematics


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