A Two-Stage High-Order Modulation Recognition Based on Projected Accumulated Constellation Vector in Non-Cooperative B5G OSTBC-OFDM Systems

Zeliang An*, Tianqi Zhang, Baoze Ma, Yuqing Xu

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

3 Citations (Scopus)


Blind modulation recognition (BMR) is a pivotal signal processing technology for cognitive receivers to reduce signaling overhead and improve transmission efficiency. Although BMR techniques have been extensively explored for single-carrier systems, only a few research have been published for OSTBC-OFDM systems. More troubling is that high-order modulation types will make the BMR harder because the constellation points are overcrowded. To remedy these flaws, we propose a two-stage high-order BMR approach that leverages low-complexity cumulants and projected accumulated constellation vector (P-ACV) to recognize high-order modulation types (e.g., 2048QAM). Firstly, zero-forcing blind equalization is employed to recover the damaged signal and enhance its feature representation. Next, the first-stage recognition module leverages the fourth-order cumulants to classify 13 modulation types into three groups, including PSK&PAM, square-shaped QAM and cross-shaped QAM groups. Finally, the second-stage recognition module distinguishes the inter-class signal in each group by P-ACV features. The temporal convolution network is built to tap the potentialities of P-ACV and speed up online inference. Numerical results demonstrate that our two-stage algorithm obtains a recognition accuracy of 97.37% when signal-to-noise-ratio (SNR) ≥ 12 dB and performs six times faster than the suboptimal method. Notably, it does not require prior knowledge, such as channel state information (CSI) and SNR conditions.

Original languageEnglish
Article number108673
JournalSignal Processing
Number of pages15
Publication statusPublished - Nov 2022
Externally publishedYes

Bibliographical note

Funding Information:
This work is supported by the National Natural Science Foundation of China (No. 61671095 , 61702065 , 61701067 , 61771085 ), the Project of Key Laboratory of Signal and Information Processing of Chongqing (No. CSTC2009CA2003 ), the Natural Science Foundation of Chongqing (No. cstc2021jcyj-msxmX0836 ) and the Research Project of Chongqing Educational Commission (No. KJ1600427 , KJ1600429 ).

Publisher Copyright:
© 2022 Elsevier B.V.


  • Beyond 5G
  • High-order modulation
  • Orthogonal space-time block coded-orthogonal frequency division multiplexing (OSTBC-OFDM) systems
  • Projected accumulated constellation vector
  • Two-stage modulation recognition


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