Publications
Journal Paper (peer reviewed)

  1. R. Hayakawa,
    “Asymptotics of proximity operator for squared loss and performance prediction of nonconvex sparse signal recovery,”
    APSIPA Transactions on Signal and Information Processing, (accepted).
    [arXiv]

  2. S. Tatsumi, R. Hayakawa, and Y. Iiguni,
    “Depth-aided color image inpainting in quaternion domain,”
    IEEE Signal Processing Letters, vol. 32, pp. 1171-1175, Mar. 2025.
    [Link]   [arXiv]

  3. T. Matsuda, R. Hayakawa, and Y. Iiguni,
    “Deep unfolding-aided parameter tuning for plug-and-play-based video snapshot compressive imaging,”
    IEEE Access, vol. 13, pp. 24867-24879, Feb. 2025.
    [Link]   [arXiv]

  4. R. Hayakawa,
    “Noise variance estimation using asymptotic residual in compressed sensing,”
    APSIPA Transactions on Signal and Information Processing, vol. 12, no. 1, e46, Nov. 2023.
    [Link]   [arXiv]

  5. R. Hayakawa,
    “Asymptotic performance prediction for ADMM-based compressed sensing,”
    IEEE Transactions on Signal Processing, vol. 70, pp. 5194-5207, 2022.
    [Link]   [arXiv]   [Code]

  6. R. Hayakawa, A. Nakai-Kasai, and K. Hayashi,
    “Discreteness and group sparsity aware detection for uplink overloaded MU-MIMO systems,”
    APSIPA Transactions on Signal and Information Processing, vol. 9, e21, 2020.
    [Link]

  7. R. Hayakawa and K. Hayashi,
    “Asymptotic performance of discrete-valued vector reconstruction via box-constrained optimization with sum of $\ell_1$ regularizers,”
    IEEE Transactions on Signal Processing, vol. 68, pp. 4320-4335, Aug. 2020.
    [Link]   [Paper]   [Code]

  8. S. Takabe, M. Imanishi, T. Wadayama, R. Hayakawa, and K. Hayashi,
    “Trainable projected gradient detector for massive overloaded MIMO channels: Data-driven tuning approach,”
    IEEE Access, vol. 7, pp. 93326-93338, Jul. 2019.
    [Link]

  9. R. Hayakawa and K. Hayashi,
    “Reconstruction of complex discrete-valued vector via convex optimization with sparse regularizers,”
    IEEE Access, vol. 6, pp. 66499-66512, Dec. 2018.
    [Link]   [Code]

  10. R. Hayakawa and K. Hayashi,
    “Discreteness-aware approximate message passing for discrete-valued vector reconstruction,”
    IEEE Transactions on Signal Processing, vol. 66, no. 24, pp. 6443-6457, Dec. 2018.
    [Link]   [Paper]   [Code]

  11. R. Hayakawa and K. Hayashi,
    “Discreteness-aware decoding for overloaded non-orthogonal STBCs via convex optimization,”
    IEEE Communications Letters, vol. 22, no. 10, pp. 2080-2083, Oct. 2018.
    [Link]   [Paper]

  12. R. Hayakawa and K. Hayashi,
    “Error recovery for massive MIMO signal detection via reconstruction of discrete-valued sparse vector,”
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, vol. E100-A, no. 12, pp. 2671-2679, Dec. 2017.
    [Link]   [Paper] (© 2017 IEICE)

  13. R. Hayakawa and K. Hayashi,
    “Convex optimization-based signal detection for massive overloaded MIMO systems,”
    IEEE Transactions on Wireless Communications, vol. 16, no. 11, pp. 7080-7091, Nov. 2017.
    [Link]   [Paper]   [Code]

  14. R. Hayakawa, K. Hayashi, and M. Kaneko,
    “Lattice reduction-aided detection for overloaded MIMO using slab decoding,”
    IEICE Transactions on Communications, vol. E99-B, no. 8, pp. 1697-1705, Aug. 2016.
    [Link]   [Paper] (© 2016 IEICE)

  15. K. Matsuoka, Y. Yushima, R. Hayakawa, R. Kawasaki, K. Hayashi, and M. Kaneko,
    “An RFID tag identification protocol via boolean compressed sensing,”
    IEICE Communications Express, vol. 5, no. 5, pp. 118-123, May 2016.
    [Link]   [Paper] (© 2016 IEICE)

International Conference (peer reviewed)

  1. S. Furusawa, K. Hayashi, K. Kameda, and R. Hayakawa,
    “Numerical performance evaluation of $\ell_1$-$\ell_2$ sparse reconstruction using optical analog circuit,”
    APSIPA ASC 2023, Taipei, Taiwan, Oct.-Nov. 2023.
    [Link]

  2. K. Kameda, R. Hayakawa, K. Hayashi, and Y. Iiguni,
    “Performance evaluation of FISTA with constant inertial parameter,”
    APSIPA ASC 2022, Chiang Mai, Thailand, Nov. 2022.
    [Link]   [Paper]

  3. K. Hayashi, A. Nakai-Kasai, A. Hirayama, H. Honda, T. Sasaki, H. Yasukawa, and R. Hayakawa,
    “An overloaded IoT signal detection method using non-convex sparse regularizers,”
    APSIPA ASC 2020, virtual conference, Dec. 2020.
    [Link]   [Paper]

  4. K. Hayashi, A. Nakai-Kasai, and R. Hayakawa,
    “An overloaded SC-CP IoT signal detection method via sparse complex discrete-valued vector reconstruction,”
    APSIPA ASC 2019, Lanzhou, China, Nov. 2019.
    [Link]   [Paper]

  5. R. Hayakawa and K. Hayashi,
    “Discrete-valued vector reconstruction by optimization with sum of sparse regularizers,”
    EUSIPCO 2019, A Coruña, Spain, Sept. 2019.
    [Link]   [Paper]   [Poster]   [Code]

  6. R. Hayakawa and K. Hayashi,
    “Performance analysis of discrete-valued vector reconstruction based on box-constrained sum of L1 regularizers,”
    ICASSP 2019, Brighton, UK, May 2019.
    [Link]   [Paper]   [Slide]

  7. K. Hayashi, A. Nakai, R. Hayakawa, and S. Ha,
    “Uplink overloaded MU-MIMO OFDM signal detection methods using convex optimization,”
    APSIPA ASC 2018, Honolulu, USA, Nov. 2018.
    [Link]   [Paper]

  8. R. Hayakawa, A. Nakai, and K. Hayashi,
    “Distributed approximate message passing with summation propagation,”
    ICASSP 2018, Calgary, Canada, Apr. 2018.
    [Link]   [Paper]   [Slide]

  9. R. Hayakawa and K. Hayashi,
    “Binary vector reconstruction via discreteness-aware approximate message passing,”
    APSIPA ASC 2017, Kuala Lumpur, Malaysia, Dec. 2017.
    [Link]   [Paper]   [Slide]

  10. R. Hayakawa and K. Hayashi,
    “Discreteness-aware AMP for reconstruction of symmetrically distributed discrete variables,”
    SPAWC 2017, Sapporo, Japan, Jul. 2017.
    [Link]   [Paper]   [Poster]

  11. R. Hayakawa and K. Hayashi,
    “Error recovery with relaxed MAP estimation for massive MIMO signal detection,”
    ISITA 2016, California, USA, Oct.-Nov. 2016.
    [Link]   [Paper]   [Slide]

  12. R. Hayakawa, K. Hayashi, H. Sasahara, and M. Nagahara,
    “Massive overloaded MIMO signal detection via convex optimization with proximal splitting,”
    EUSIPCO 2016, Budapest, Hungary, Aug.-Sept. 2016.
    [Link]   [Paper]   [Poster]

  13. R. Hayakawa, K. Hayashi, and M. Kaneko,
    “An overloaded MIMO signal detection scheme with slab decoding and lattice reduction,”
    APCC 2015, Kyoto, Japan, Oct. 2015.
    [Link]   [Paper]