Low-Complexity Equalization of OFDM in Doubly Selective Channels

2004 ◽  
Vol 52 (4) ◽  
pp. 1002-1011 ◽  
Author(s):  
P. Schniter
Keyword(s):  
Low Complexity ◽  
Doubly Selective Channels

Low-Complexity ICI Cancellation Based on BEM for OFDM Systems over Doubly Selective Channels

2013 ◽  
Vol E96.B (6) ◽  
pp. 1588-1596 ◽  
Author(s):  
Suyue LI ◽  
Jian XIONG ◽  
Peng CHENG ◽  
Lin GUI ◽  
Youyun XU
Keyword(s):  
Low Complexity ◽  
Ofdm Systems ◽  
Doubly Selective Channels ◽  
Ici Cancellation

scholarly journals Low Complexity Equalization of Orthogonal Chirp Division Multiplexing in Doubly-Selective Channels

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3125
Author(s):  
Xin Wang ◽  
Zhe Jiang ◽  
Xiao-Hong Shen
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Low Complexity ◽  
Circulant Matrices ◽  
Modulation Scheme ◽  
Doubly Selective Channels ◽  
Channel Matrix ◽  
Band Matrix ◽  
Transform Matrix ◽  
Ber Performance

Orthogonal Chirp Division Multiplexing (OCDM) is a modulation scheme which outperforms the conventional Orthogonal Frequency Division Multiplexing (OFDM) under frequency selective channels by using chirp subcarriers. However, low complexity equalization algorithms for OCDM based systems under doubly selective channels have not been investigated yet. Moreover, in OCDM, the usage of different phase matrices in modulation will lead to extra storage overhead. In this paper, we investigate an OCDM based modulation scheme termed uniform phase-Orthogonal Chirp Division Multiplexing (UP-OCDM) for high-speed communication over doubly selective channels. With uniform phase matrices equipped, UP-OCDM can reduce the storage requirement of modulation. We also prove that like OCDM, the transform matrix of UP-OCDM is circulant. Based on the circulant transform matrix, we show that the channel matrices in UP-OCDM system over doubly selective channels have special structures that (1) the equivalent frequency-domain channel matrix can be approximated as a band matrix, and (2) the transform domain channel matrix in the framework of the basis expansion model (BEM) is a sum of the product of diagonal and circulant matrices. Based on these special channel structures, two low-complexity equalization algorithms are proposed for UP-OCDM in this paper. The equalization algorithms are based on block LDL H factorization and iterative matrix inversion, respectively. Numerical simulations are finally proposed to show the performance of UP-OCDM and the validity of the proposed low complexity equalization algorithms. It is shown that when the channel is doubly selective, UP-OCDM and OCDM have similar BER performance, and both of them outperform OFDM. Moreover, the proposed low complexity equalizers for UP-OCDM both show better BER performance than their OFDM counterparts.

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