Nondata-aided error vector magnitude based adaptive modulation over rapidly time-varying channels
A novel nondata-aided error vector magnitude based adaptive modulation(NDA-EVM-AM) was proposed to solve the problem of lower spectral efficiency over rapidly time-varying wireless channels.Namely,NDA-EVM was considered as a metric to reflect the rapid change of time-varying channels.The unified mod...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Editorial Department of Journal on Communications
2017-03-01
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| Series: | Tongxin xuebao |
| Subjects: | |
| Online Access: | http://www.joconline.com.cn/zh/article/doi/10.11959/j.issn.1000-436x.2017065/ |
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| Summary: | A novel nondata-aided error vector magnitude based adaptive modulation(NDA-EVM-AM) was proposed to solve the problem of lower spectral efficiency over rapidly time-varying wireless channels.Namely,NDA-EVM was considered as a metric to reflect the rapid change of time-varying channels.The unified model to calculate different modulation order of NDA-EVM was analytically derived,with which the relationship between NDA-EVM and bit error rate (BER) for each modulation order was presented.Thereafter,the mechanism to adaptively select the modulation orders of multilevel quadrature amplitude modulation (MQAM) signals was designed to guarantee the predefined BER.Taking the two rapidly time-varying channels proposed for high-speed railway scenarios as examples,numerical results are conducted to verify the effectiveness of the proposed algorithm.It shows that NDA-EVM estimation has the lest root mean square error than data-aided error vector magnitude (DA-EVM) estimation and signal to noise ratio estimation.The proposed algorithm has better accuracy in aspects of channel quality estimation and modulation orders adjustment,Compared with conventional data-aided error vector magnitude based-adaptive modulation (DA-EVM-AM),the accuracy improves by 7.9%,spectral efficiency improves by 0.53 bit·s<sup>−1</sup>·Hz<sup>−1</sup>,and compared with signal to noise ratio based-adaptive modulation (SNR-AM),the accuracy improves by 15.7%,spectral efficiency improves by 0.82 bit·s<sup>−1</sup>·Hz<sup>−1</sup>. |
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| ISSN: | 1000-436X |