نمونه متن انگلیسی مقاله
As a new type of Low Power Wide Area technology, the Narrow Band Internet of Things (NB-IoT) technology supports wide coverage and low bitrate services, thus it has a great potential to be the future commercial technology of Low Power Wide Area Network (LPWAN). Therefore, it has attracted attention of both academia and industry. In this paper, we present the NB-IoT development, and main characteristics and design objectives of NB-IoT according to 3GPP R13. In addition, we provide the review of related literatures about NB-IoT modeling and algorithm analysis. And we explain current problems of NB-IoT system-level modelling based on visualized simulation platform. Moreover, this study is devoted to construction of NB-IoT model based on OPNET and verification of its characteristics, such as wide coverage and high channel utilization. This study mainly considers NB-IoT model design and realization in terms of NB-IoT physical layer characteristics. We summarize the correlated characteristics of NB-IoT uplink and downlink. Then we design and construct the NB-IoT model based on Long Term Evolution (LTE) network. Lastly, we use the constructed NB-IoT model for simulations and conduct an experiment on it using the LTE network with channel bandwidths of 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. The simulation results have verified the performance of NB-IoT, wherein uplink time delay is lower than 10 s, channel utilization is higher than that of LTE network, and coverage area is larger than LTE network.
Nowadays, due to continuous development of Internet of Things (IoT), the IoT communication technology is increasingly mature . IoT has achieved significant improvement in big data processing , heterogeneity , and performance . The IoT technologies can be separated into two categories from the aspect of communication distance: shorthaul communication technologies (such as Zigbee, Wi-Fi, Bluetooth, Z-wave, etc.) and Low Power Wide Area (LPWA) technologies desired by Low power wide area machine-tomachine networks: key techniques and prototype   . Among them, the LPWA technologies have a significant development. The LPWA technologies can be separated into two types by whether the frequency spectrum is authorized or not: technologies that work in unauthorized frequency band (such as Lora, Sigfox, and etc.) are mostly nonstandard and realized as user-defined, and technologies that work in authorized frequency band, including GSM, CDMA, WCDMA and other relatively mature 2G/3G cellular communication technologies, as well as the LTE and its evolution technologies, are gradually deployed and applied at present and support different categories of devices, also these technologies have almost made standard definition of 3GPP (mainly formulating the relevant standards for GSM, WCDMA, LTE and its evolution technologies) and 3GPP2 (mainly formulating the relevant standards for CDMA) and other international standard organizations.