Collaborative Blind Equalization for Time-Varying OFDM Applications Enabled by Normalized Least Mean and Recursive Square Methodologies

IEEE Access

Yuanhua He¹  Li Deng¹  Yong Mao Huang²  Xiubao Sui³  Qian Chen³ 

[1] School of Civil Aviation Safety Engineering, Civil Aviation Flight University of China, Guanghan, China;School of Electrical and Electronic Information, Xihua University, Chengdu, China;School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing, China;

关键词: Blind equalization;    normalized least mean square (NLMS);    orthogonal frequency division modulation (OFDM);    recursive least square (RLS);    time-varying channel;   

DOI  :  10.1109/ACCESS.2020.2999387

来源: DOAJ

【 摘 要 】

In this work, a collaborative blind equalization method for the orthogonal frequency division multiplexing (OFDM) signals in time-varying channels is presented. Equalizers are eliminated the inter-symbol interference (ISI) in the received signals caused by channel distortions. The conventional adaptive equalization requires sending the training-sequences periodically to synthesize the channel model, which can only provide redundant information, and consequently decrease the channel utilization and complicate the system. To overcome this drawback, the blind equalization methods, which need not send the training-sequences periodically, is developed. However, the conventional blind equalization methods still suffer from various disadvantages. The normalized least mean square (NLMS) method is able to converge rapidly, whereas its equalization error is relatively large. The recursive least square (RLS) method has smaller steady-state error but low convergence rate, demanding massive training sequences. To further enhance the equalization performance of time-varying OFDM systems, which is typically with massive calculation, a collaborative blind equalization is proposed in this work, which is able to effectively combine the characteristics of the conventional NLMS and RLS methods together. The numerical simulations demonstrate the proposed LM-RS method can exhibit quite good performance. Particularly, as compared with the conventional NLMS and RLS methods, the proposed LM-RS method achieves smaller steady-state error and lower complexity, as well as similar convergence rate. All these results indicate that the proposed collaborative LM-RS blind equalization method is suitable for the OFDM transmission under the time-varying wireless application environments.

【 授权许可】

Unknown