未授权频段LTE-LAA与WiFi共存系统性能分析

Performance analysis for coexisting system of LTE-LAA and WiFi in unlicensed band

为分析在未授权频段授权辅助接入(LAA)框架与无线局域网802.11系列标准(Wi Fi)共存的系统公平性问题,基于当前LAA框架的类型B(type B),建立了LAA系统与Wi Fi系统的共存模型.使用二维离散马尔可夫(Markov)模型对type B接入过程的‘说之前听’类型3(LBT Cat3)进行建模分析,进而建立共存模型.通过更改共存的设备数量和LAA设备的LBT Cat3参数,分析LAA设备与Wi Fi设备在共存场景中的性能.根据分析模型创建相应仿真场景,以验证分析模型性能.分析计算结果与仿真计算结果表明,提出的分析模型在不同LAA与Wi Fi设备数量比和不同LBT Cat3参数情况下均能有效预测共存的LAA与Wi Fi设备成功占用信道比率.LAA系统适当调整LBT Cat3参数可以实现与Wi Fi系统公平共存和最大化信道利用率.

To analyze the problem in the unlicensed band,the fairness of coexisting licensed-assisted access(LAA)and802.11WLAN(W iFi)systems,based on the type B access procedure,this paper proposed a coexisting model for the LAA system and WiFi system.A discrete-time twodimensional Markov chain was used to model and analyze the listen-before-talk category3(LBT Cat3)in type B access procedure,and then a coexistence model was established.The performance of the LAA device and WiFi device in the coexistence scenario was analyzed by changing the quantity of the coexisting device and the LBT Cat3parameters of the LAA device.The simulation scenario was setup according to the analysis model to verify the performance of the analysis model.The performance of the using LBT Cat3LAA device and WiFi device in the coexisting scenario is analyzed.The analysis result and the simulation result show that the analyzing model is valid in predicting the successful airtime share of the LAA and WiFi device in case of the different coexisting LAA to WiFi device number ratios and different LBT Cat3parameters.LAA system can appropriately adjust the parameters of LBT Cat3to achieve the fairness coexistence with WiFi and maximize channel utilization.