| With the development of digital communication technology,new communication services put forward higher quality requirements of Power Line Communication(PLC)technology.The use of existing power line architectures can effectively transmit high-quality communication signals with significant economic and social benefits.As Multi-input Multi-output power line communication(MIMO-PLC)can confront the channel multipath fading,improve the reliability and channel capacity of PLC channel potentially and efficiently,it has received more and more attention.In the view of the current research of MIMO-PLC channel characteristics are still insufficient and the domestic reports of MIMO-PLC technology researches are much rarer,this paper studied the characteristics of MIMO-PLC channel in 2~100MHz broadband comprehensively and deeply.Based on the theory of multi-conductor transmission lines,a reliable model for broadband MIMO-PLC channel is established.Combined the model and measured data,the MIMO-PLC channel characteristics in 2~100MHz are studied in detail.A MIMO-PLC random paramaters channel model is established based on the improved model,and a hybrid modeling for MIMO-PLC channel is proposed.The noise characteristics of MIMO-PLC channel in 2~100MHz are studied in detail for the first time by using frequency slice wavelet transform.A relay model is proposed,and the influence of relay on MIMO-PLC channel characteristics is studied in detail for the first time.The purpose of this paper aims to carry out comprehensive and sufficient research on the MIMO-PLC channel characteristics,provide theoretical and data support for the design of MIMO-PLC system,and promote the further development of MIMO-PLC technology.The main contents and research contributions are summarized as follows:(1)An improved model for broadband MIMO-PLC channels is proposed.The primary line constants of the common low-voltage indoor distribution network cables are studied in detail,the change of the primary line contants with frequency of common cables are revealed.Based on the multi-conductor transmission line theory,the modeling process of the MIMO-PLC channel is analyzed.Considering the insulating materials electrical characteristics,an improved MIMO-PLC channel model is proposed.Based on the improved model the broadband MIMO-PLC channel with and without branch are modeled accurately,and the calculated values are compared with the measured data.The results show that the numerical values and the measured values match well,and the results are reasonable.The proposed models provide effective tools for the analysis of MIMO-PLC channel characteristics.(2)The characteristics of broadband MIMO-PLC channel variation with channel topology and the noise characteristics of broadband MIMO-PLC channel are analyzed systematically.MIMO-PLC networks with multiple topologies are designed and constructed.A large number of measurements are carried out by using a network analyzer on the transfer functions and input impedances of each topology network.Based on the measured data and combined with the proposed MIMO-PLC channel models,the quantitative analysis of how the branch length,branch position and branch number affect the MIMO-PLC channel characteristics are investigated and analyzed.The model of online channel is established,and compared with the measured results,which proves the correctness of the modeling methods further.The noises of MIMO-PLC channel is measured,and the characteristics of MIMO-PLC channel noises in broadband range are studied by frequency slicing wavelet transform.These studies are important for simplifying the research of MIMO-PLC channel characteristics,system design and engineering application.(3)The characteristics of MIMO-PLC random parameters channel are studied comprehensively for the first time.A hybrid modeling approach for broadband MIMO-PLC channels is proposed,and the broadband MIMO-PLC channel characteristics under different bandwidths are studied.Using the proposed improved model,a broadband MIMO-PLC stochastic parameters model for specific scenarios is established,and the stochastic parameters broadband MIMO-PLC channel characteristics are studied comprehensively.In the model,the physical parameters of the channels are characterized by specified statistical distributions,and the characteristics of the broadband MIMO-PLC channel with different branches and parameters are analyzed.A hybrid model which combined the top-down and bottom-up modeling approaches is proposed to analyze of broadband MIMO-PLC channels,which provides a prior MIMO channel generator.Based on the realized channel,the channel characteristics and parameters in 2~30 MHz and 2~100 MHz frequency bands are investigated further.(4)The influence of relay on MIMO-PLC channel characteristics is analyzed in detail for the first time.Based on the direct-link broadband MIMO-PLC channel models,the relay-aided MIMO-PLC channel models are proposed in amplify-and-forward(AF)mode.The influences of a relay on MIMO-PLC channel characteristics are analyzed theoretically. |
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