| This paper studies and analyses the technical principle and key technology of NBIoT,introduces the construction of NB-IoT network platform and the scheme of wireless network and core network construction for mobile operators,and tests and verifies the coverage comparison between NB-IoT and GSM and the single station coverage capability of NB-IoT.At the same time,the main urban area of Zhengzhou is selected,and the 1:N(NB-IoT: FDD)network is simulated and tested using APC software of the planning simulation cloud center.The coverage and interference under different station spacing are obtained.Finally,select the dense and general urban areas of Hangzhou,all open or open a certain proportion of NB-IoT sites,verify the depth coverage of NB-IoT outdoor roads and buildings and the satisfaction of planning indicators,guide network planning and construction,and provide ideas and strategies for mobile operators to carry out NB-IoT planning,construction and networking.The main work and achievements of this paper are as follows:1.The technical principle,technical characteristics,technical system partition,service network architecture and frequency planning of the Internet of Things are analyzed.NB-IoT adopts 200 K ultra-narrowband design,FDD working mode,strong coverage,low cost,supports ultra-Dalian connection and cell reselection,but does not support handover and voice,which is suitable for the development of low-rate services in narrowband Internet of Things.NB-IoT is a separate network independent of 2/3/4G,logically independent network,physically able to achieve LTE FDD and GSM in the same band in RRU and feed-in the same band.Use equipment.2.The network construction scheme of NB-IoT is studied,including network platform construction scheme,wireless network and core network construction scheme.The CMP of mobile operators is unified by China Mobile Internet of Things,which includes Internet of Things business support system and Internet of Things transport management platform.At present,the support system of the Internet of Things consists of the business support system of the Internet of Things,the operation and management platform of the Internet of Things and the core network elements of the Internet of Things.The operation and management platform of the Internet of Things and the two-level business support system share the functions of the CMP platform of the Internet of Things.At present,there are two ways to construct China Mobile's NB-IoT wireless network: based on GSM base station and based on TDD site.In the aspect of core network,the deployment scheme of NB-IoT core network includes two construction schemes: upgrade of current network EPC to support NB-IoT and establishment of independent NB-IoT core network(NFV mode).The advantages and disadvantages of the two schemes are analyzed.3.The comparison of coverage between NB-IoT and GSM is studied,and the difference of coverage performance between NB-IoT and GSM network is obtained.This chapter mainly studies the NB-IoT coverage enhancement methods,compares and analyses the coverage capabilities of NB-IoT and GSM,and tests and verifies them in combination with the actual situation.Through comparing indoor fixed-point test,elevator internal test,underground garage test and outdoor pull-out test,it is concluded that the NB-IoT network is superior to the GSM network in terms of indoor depth coverage and outdoor wide coverage.4.By planning and simulating the APC network planning platform of cloud center and using SPM propagation model,the conclusion is drawn through simulation analysis,which provides reference for the construction of NB-IoT.Finally,it is concluded that the proportion of RSRP value greater than or equal to-83.7dBm is 97.1%,SINR value greater than or equal to-3dB is 98.2%,meeting the requirements of planning indicators and verifying that 1:4 networking initially meets the demand of NB networking,1:2 networking meets the demand of NB network capacity development and has the FDD broad coverage level,and 1:1 networking meets the FDD 1M/4M wide coverage level.Ability requirements.5.Select Hangzhou's dense urban areas and general urban areas for 1:N networking test,open or open a certain proportion of NB-IoT sites,for FDD LTE/Internet of Things joint planning,carry out NB-IoT planning,construction,networking multi-scenario testing work,verify the depth coverage of NB-IoT outdoor roads and buildings and planning indicators meet the situation.Through outdoor road traversal test and indoor depth coverage fixed-point test,the coverage enhancement margin of relative GSM in 1:1 and 1:4 scenarios and the satisfaction of planning indicators are obtained to guide network planning and construction. |
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