Research On New Multi-carrier Technology In Low Power And Large Connection

Massive machine communication in 5G application scenarios is a hot topic at present.It has the characteristics of low-power consumption,large-connection,and mass user access.It is proposed to cope with a large number of outdoor Internet of Things devices.In the application,it is mainly used for smart city,smart agriculture and other scenarios.Among them,the intelligent equipment of the underground confined space has attracted much attention because of its closeness to the scene of life.Intelligent equipment for underground confined space has problems such as large numbers of users,extremely high daily maintenance costs such as battery replacement,etc.,and require low-power and large-connection in the scene.In order to improve the performance of Intelligent equipment and reduce the cost of use,this papre starts from the low-power large-connection scenarios,and plans and designs the 5G physical layer technology.Considering the shortcomings of large out-of-band leakage and low spectrum utilization when Orthogonal Frequency Division Multiplexing(OFDM)technology is applied in low-power large-connection scenarios,a new multi-carrier technology is proposed.In a confined space,the terminal is sensitive to the efficiency of the power amplifier,and the movement of the transceiver is prone to generate Doppler effects that lead to frequency offsets.Frequency offset will cause inter-carrier interference.Therefore,intelligent devices in underground confined spaces require Peak-to Average Power Ratio(PAPR)and Intercarrier Interference(ICI)suppression Extremely high.Therefore,this paper mainly studies the new multi-carrier technology to reduce the peak-to-average power ratio and ICI suppression in low-power and large-connection scenarios.The research content is as follows:First,there are many traditional methods to reduce PAPR in the new multi-carrier technology in low-power large-connection scenarios.The more mature solutions are partial sequence transmission(PTS)and selective mapping(SLM).The two schemes reduce PAPR by scrambling the input data block,but when the number of subcarriers is increased,the number of data blocks that need to be scrambled will also increase,and the system's spectrum efficiency will decrease and the complexity will increase.Not suitable for applications in low-power and large-connection scenarios.this paper proposes a DFT spreading method usinga centralized FDMA allocation method based on the multi-user implementation of frequency division multiple access.This technology makes full use of DFT spreading The single carrier effect of the technology has low implementation complexity.Simulation experiments prove that this method can effectively reduce the PAPR of the new multi-carrier system.Compared with SLM technology and PTS technology,the proposed scheme has better ability to reduce PAPR.Secend,Aiming at the problem of inter-subcarrier interference in the new multi-carrier system,the Universal Filtered Multi-Carrier(UFMC)and Filter Bank Multicarrier with Offset Orthogonal Amplitude Modulation(FBMC)systems are studied separately.Firstly,a partially symmetrical data reversal and time-domain windowing scheme suitable for UFMC system is proposed.This solution uses a special encoding process that symmetrically inverts part of the data in the frequency domain of the sender.Compared with the original ICI self-cancellation scheme,the frequency band utilization is improved,but the anti-interference performance is reduced because the proportion of self-cancellation subcarriers is reduced.In order to balance the system's anti-interference ability and frequency band utilization rate,time-domain windowing is performed on the received signal at the receiving end to make up and improve the anti-interference ability.When the scheme is actually adopted,the parameters can be selected according to the performance requirements and the frequency band utilization ratio.Then analyze the ICI of the FBMC system.Because FBMC uses OQAM modulation,it effectively avoids the generation of inter-carrier interference.This article describes in detail how the OQAM modulation module avoids the generation of ICI.This paper studies the new multi-carrier technology and optimizes its performance in low-power and large-connection scenarios.The experimental results of the improved algorithm can provide technical support for the connection of intelligent equipment systems in underground confined spaces.