License assisted access(LAA) was proposed as a solution to the challenge of satisfying high throughput requirement in cellular network with limited licensed band. LAA uses long term evolution(LTE) carrier aggregation ...License assisted access(LAA) was proposed as a solution to the challenge of satisfying high throughput requirement in cellular network with limited licensed band. LAA uses long term evolution(LTE) carrier aggregation technique to combine licensed and unlicensed bands, specifically 5 GHz Wi Fi band, in order to achieve high data rates. However, LAA has several critical concerns for services provision on 5 GHz unlicensed band. In this article, an overview of the techniques concerning the coexistence of LTE and Wi Fi on the same unlicensed band is presented. We first present several general approaches including power control of LTE evolved Node B(e NB), carrier selection, LTE duty cycling, self clear to send(CTS) and request to send/CTS(RTS/CTS), and listen before talk(LBT). Then, we focus on LBT techniques for LAA-Wi Fi coexistence and discuss how LBT based coexistence solutions can dynamically respond to the variations in network load and ensure fair coexistence in a distributed manner. Based on the LBT mechanism, we also present a fairness-aware LAA-WiF i coexisting scheme with TXOP(transmitted in a single transmission opportunity) backoff for LAA e NB. Finally, the performances of various LBT solutions for LAA-Wi Fi coexistence are evaluated using Markov chain analytical model.展开更多
授权频谱辅助接入技术(License Assisted Access,LAA)可以把LTE网络部署在未授权频段上.为了与Wi-Fi网络友好共存,LAA网络采用先听后说(Listen Before Talk,LBT)机制.但是,LAA和Wi-Fi共存网络的性能很大程度上取决于LBT中的退避机制,而...授权频谱辅助接入技术(License Assisted Access,LAA)可以把LTE网络部署在未授权频段上.为了与Wi-Fi网络友好共存,LAA网络采用先听后说(Listen Before Talk,LBT)机制.但是,LAA和Wi-Fi共存网络的性能很大程度上取决于LBT中的退避机制,而竞争窗口的增加则是由当前传输机会(Transmission Opportunity,TXOP)的混合自动重传请求(Hybrid Automatic Repeat Request,HARQ)反馈情况来决定的.为此,本文首先利用LightGBM等6种机器学习算法,对TXOP第一个子帧的HARQ反馈的NACK占比是否达到80%进行了预测,由于LightGBM算法91.6%的准确率和0.98的AUC值(Area Under Curve),故选其作为实时预测模型.结果表明,采用了本文所提出的竞争窗口自适应预调整机制的LAA/Wi-Fi混合网络相比于没有采用该机制的LAA/Wi-Fi混合网络,吞吐量提升了21.266%.展开更多
基金supported in part by Joint Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) and Research Grants Council Earmarked Research Grants (RGC ERG) with Grant 20130142140002National Science Foundation of China with Grants 61531011 and 61471163Major Program of National Natural Science Foundation of Hubei in China with Grant 2016CFA009
文摘License assisted access(LAA) was proposed as a solution to the challenge of satisfying high throughput requirement in cellular network with limited licensed band. LAA uses long term evolution(LTE) carrier aggregation technique to combine licensed and unlicensed bands, specifically 5 GHz Wi Fi band, in order to achieve high data rates. However, LAA has several critical concerns for services provision on 5 GHz unlicensed band. In this article, an overview of the techniques concerning the coexistence of LTE and Wi Fi on the same unlicensed band is presented. We first present several general approaches including power control of LTE evolved Node B(e NB), carrier selection, LTE duty cycling, self clear to send(CTS) and request to send/CTS(RTS/CTS), and listen before talk(LBT). Then, we focus on LBT techniques for LAA-Wi Fi coexistence and discuss how LBT based coexistence solutions can dynamically respond to the variations in network load and ensure fair coexistence in a distributed manner. Based on the LBT mechanism, we also present a fairness-aware LAA-WiF i coexisting scheme with TXOP(transmitted in a single transmission opportunity) backoff for LAA e NB. Finally, the performances of various LBT solutions for LAA-Wi Fi coexistence are evaluated using Markov chain analytical model.
