窄带物联网覆盖类别更新机制性能分析与优化

Performance analysis and optimization for coverage classes updating mechanism of narrow-band internet of things

以覆盖类别为状态变量建立了窄带物联网(NB-IoT, narrow-band internet of things)覆盖类别更新机制的马尔可夫链模型,给出了平均接入失败概率和平均功耗的优化模型及求解办法,分析了前导码重复次数、系统负载、全局最大传输次数对各覆盖类别最大传输次数最优取值的影响。数值分析表明:常规覆盖类别和扩展环境覆盖类别的最大传输次数对系统性能影响较大,最大传输次数取值范围应分别控制在[1,5]和[1,7]之间;极端环境覆盖类别的最大传输次数对系统性能影响不大,可取[1,10]之间的任意值,建议取值为1;所提的引入覆盖类别回退机制的覆盖类别更新机制的平均功耗比协议模型低约95%。

A Markov chain model with coverage classes as state variables was established to describe the dynamics of the coverage classes updating mechanism of narrow-band internet of things （NB-IoT）. An optimization model to minimize average probability of access failure as well as average power consumption was formulated, with which the effects of preamble repetition number, system load and global maximum transmission number on the optimal configuration of maximum transmission number of each coverage class was analyzed. Numerical analysis results show that the maximum transmission number of normal coverage and extended coverage have a great influence on the system performance and their value ranges should be set within [1,5] and [1,7] respectively. However, the maximum transmission number of extreme coverage has little influence on the system performance, its value could be any one in [1,10] but the recommended value is 1. In addition, the average power consumption of the model that introduced coverage classes’ rollback mecha-nism is about 95% lower than the model proposed by 3GPP.