CONCLUSION
This article introduces a development of NB-IoT technology and its main characteristics and design objectives according to 3GPP R13. In addition, the related literature about NBIoT modelling and algorithm analysis is presented. Then we explain current problems of NB-IoT system-level modelling based on visualized simulation platform. Nevertheless, this paper constructs a NB-IoT model based on OPNET, and verifies its characteristics, such as wide coverage, high channel utilization, and etc.. In this study, we focused on model design and realization aiming at physical layer characteristics of NB-IoT. We analyzed correlated uplink and downlink characteristics of NB-IoT, and designed and constructed the NB-IoT model based on LTE network. Lastly, we used the constructed NBIoT model to perform simulations, and we compared NB IoT network with LTE network under channel bandwidth of 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. The simulation results have verified the NB-IoT performance defined by 3GPP, that NB-IoT uplink time delay is lower than 10 s, channel utilization is higher than in LTE network, and coverage area is larger than in LTE network. The discussions and modelling presented in this paper aim to provide a comprehensive overview and big-picture of exciting solutions on this subject. In our future work, we will continue to design and improve the NB-IoT model based on OPNET. Nevertheless, we will further improve and optimize air interface layer, access network and core network of NB-IoT based on LTE network, in order to reach the expected requirements.
