Research On NB-IoT Network Optimization And Energy Harvesting Technology

Narrow Band Internet of Things(NB-IoT),as an important communication technology to realize the interconnection of everything,aims to provide seamless connectivity for large-scale Io T devices with low throughput,low power consumption and long-distance communication.NB-IoT is built on a cellular network and only consumes about 180 k Hz of bandwidth.It can be directly deployed on a GSM network or an LTE network to achieve a smooth upgrade of the network and reduce deployment costs.In order to effectively solve two problems,one is that in the traditional heterogeneous cellular network,due to the power difference between the macro base station and the small base station,most users choose to communicate with the macro base station,resulting in the problem of unbalanced network load,and the other is access to The number of devices in the Internet of Things is too large.In order to support the communication of NB-IoT devices,the energy shortage caused by the battery drive of the device,this thesis studies the network optimization and energy harvesting technology in NB-IoT.The main research contents of this thesis are as follows.(1)Aiming at the problem of how to dynamically allocate limited resources in a heterogeneous network system,a utility energy efficiency optimization algorithm combining user association and power control is proposed.Under the condition of ensuring the quality of user service,the algorithm adopts the base station sleep strategy while users are associated to improve the coverage of the system.And it adopts iterative power control algorithm,aiming at maximizing the total utility energy efficiency in the system,and solves it by transforming the optimization problem into a mixed-integer nonlinear programming problem.After using the user association method to solve the problem of system load imbalance,the Lagrangian dual problem is used to solve the power control problem to improve the utility and energy efficiency of the system.Through the numerical results of the simulation experiment,the proposed user association scheme and power control algorithm based on the sleep strategy can effectively improve the system coverage and utility energy efficiency.(2)Aiming at the massive connection in the NB-IoT network,which leads to the shortage of battery-driven energy for terminal devices,a network performance optimization algorithm for the NB-IoT system based on SWIPT(Simultaneous Wireless Information and Power Transfer)technology is proposed.SWIPT technology can efficiently increase the transmission rate of the system and realize green communication.This algorithm introduces SWIPT technology into the narrowband Internet of Things,and models the spatial distribution of radio frequency sources in the surrounding environment as the ?-Deciantal Point Process,reflecting the existence of repulsive forces between radio frequency sources,assuming that the channel obeys the Nakagami-m distribution.By optimizing the allocation of the energy collection time of the source node and the node information transmission time slot in each time slot,the average value of energy collected by the system,interruption probability and maximum transmission rate are effectively improved,and the continuous and stable operation of the terminal equipment is ensured.