3GPP LTE授权辅助接入性能分析  

Performance Analysis of LTE Licensed Assisted Accesson Unlicensed Spectrum

作　　者：冉懋海[1] 秦江伟[1] 裴二荣[2] RAN Maohai;QIN Jiangwei;PEI Errong(Chongqing Electric Power College,Chongqing 400053,China;School of Communication and Infonnation Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,China)

机构地区：[1]重庆电力高等专科学校,重庆400053 [2]重庆邮电大学通信与信息工程学院,重庆400065

出　　处：《重庆理工大学学报（自然科学）》2021年第2期159-168,共10页Journal of Chongqing University of Technology：Natural Science

基　　金：国家自然科学基金项目(61671096,61379159);重庆基础前沿和探索项目(cstc2018jcyjAX0507,cstc2017jcyj BX0005)。

摘　　要：深入分析3GPP提出的LTE授权辅助接入(LAA)方案的性能并给出改进建议。首先,考虑到3GPP LAA不同于其他LAA方案以及IEEE 802.11 DCF的特点,将其建模成一个新的二维离散马尔可夫模型,并基于该模型对其性能指标进行理论推导,得出LAA和WiFi用户的碰撞概率和信道占用率的封闭表达式。对基于线性退避的LAA方案和基于固定竞争窗口的LAA方案进行研究,并推导出性能指标的表达式。实验仿真和数值计算结果证明了提出的马尔可夫链模型的有效性。实验结果表明:3GPP LAA方案是3种方案中最友好的方案,当LAA SBSs个数较小时,3GPP LAA方案下的信道利用率最低,而较大时信道利用率最大。然而,根据"优雅共存"的定义,其他2种方案仍然是友好共存的方案。The performance of LTE licensed assisted access(LAA)is deeply analyzed and some advices are given.Considering the characteristics that the 0033GPP LAA scheme is different from other LAA schemes and IEEE 802.11 distributed coordination function(DCF)protocol in WiFi systems,it is modeled as a new two-dimensional discrete Markov model,and the closed-form expression for the collision probability and channel occupancy probability for LAA and WiFi users are further derived based on the proposed model.In order to deeply analyze 3GPP LAA scheme by comparisons,we also derive the expressions of the same performance indices for the linear backoff based LAA scheme and the fixed contention window based LAA scheme.The simulation and numerical results prove the validity of the proposed Markov chain model,and also show that the 3GPP LAA scheme is the friendliest one to WiFi networks among the three LAA schemes while its total channel occupancy utilization is the lowest when the number of LAA small base stations(SBSs)is little and that is the highest when large.However,the other two LAA schemes are still the graceful coexistence,which is defined as the scheme where the interference to WiFi users caused by LAA SBSs coexisting with them is not more than that caused by other WiFi APs replacing the LAA SBSs.

关 键 词：授权辅助接入 WIFI LBT MARKOV 系统共存 

分 类 号：TN929.5[电子电信—通信与信息系统]