J4 ›› 2011, Vol. 38 ›› Issue (5): 20-26.doi: 10.3969/j.issn.1001-2400.2011.05.004

• Original Articles • Previous Articles     Next Articles

Novel modulation identification scheme for subcarriers of OFDM signals in the multipath channel

LIU Mingqian;LI Bingbing;ZHAO Lei   

  1. (State Key Lab. of Integrated Service Networks, Xidian Univ., Xi'an  710071, China)
  • Received:2011-02-21 Online:2011-10-20 Published:2012-01-14
  • Contact: LIU Mingqian E-mail:mqliu@mail.xidian.edu.cn

Abstract:

In view of modulation identification of subcarriers of orthogonal frequency division multiplexing(OFDM) signals with a pilot in a multipath channel is a difficult problem in the non-cooperation communications system, a novel method for recognition of the subcarriers modulation of OFDM signals is proposed. The method firstly removes the null carrier signals of the OFDM using the combination characteristic of fourth-order and second order cumulants, and then filters out the pure pilot subcarrier signals and some of the modulated subcarrier signals with a pilot by the combination feature of fourth-order and sixth-order cumulants. Finally, it recognizes the modulated subcarrier signals which are less affected by pilots with the improved subtractive cluster method. Simulation results show that the proposed method has robust recognition performance in the multipath channel.

Key words: modulation recognition, OFDM, high-order cumulant, subtractive clustering

CLC Number: 

  • TN911.7