A Simple and Robust Equalization Algorithm for Variable Modulation Systems

This paper proposes a simple and robust variable modulation-decision-directed least mean square (VM-DDLMS) algorithm for reducing the complexity of conventional equalization algorithms and improving the stability of variable modulation (VM) systems. Compared to conventional adaptive equalization alg...

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Bibliographic Details
Published in:Electronics (Basel) Vol. 10; no. 20; p. 2496
Main Authors: Hu, Wanru, Wang, Zhugang, Mei, Ruru, Lin, Meiyan
Format: Journal Article
Language:English
Published: Basel MDPI AG 01.10.2021
Subjects:
Adaptive algorithms
Algorithms
Bit error rate
Complexity
Consumption
Data transmission
Decisions
Efficiency
Equalization
Global positioning systems
GPS
Low earth orbit satellites
Modulation
Quadrature phase shift keying
Robustness
Satellite communications
Systems stability
Training
ISSN:2079-9292, 2079-9292
Online Access:Get full text
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Summary:This paper proposes a simple and robust variable modulation-decision-directed least mean square (VM-DDLMS) algorithm for reducing the complexity of conventional equalization algorithms and improving the stability of variable modulation (VM) systems. Compared to conventional adaptive equalization algorithms, known information was used as training sequences to reduce the bandwidth consumption caused by inserting training sequences; compared with conventional blind equalization algorithms, the parameters and decisions of the equalizer were determinate, which was conducive to a stable equalization performance. The simulation and implementation results show that the proposed algorithm has a better bit error rate (BER) performance than that of the constant modulus algorithm (CMA) and modified constant modulus algorithm (MCMA) while maintaining the same level of consumption of hardware resources. Compared to the conventional decision-directed least mean square (DDLMS) algorithm, the proposed algorithm only needs to make quadrature phase shift keying (QPSK) symbol decisions, which reduces the computational complexity. In parallel 11th-order equalization algorithms, the operating frequency of VM-DDLMS can reach up to 333.33 MHz.
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ISSN:2079-9292
2079-9292
DOI:10.3390/electronics10202496