| Reasonable spectrum usage strategies can relieve contradiction between the substantial growth in mobile data traffic and the scarcity in spectrum resource.Spectrum re-farming is one of the key strategies to ensure efficient usage of spectrum.The research on this dissertation is focused on the technologies in spectrum re-farming.Firstly,the investigation background and significance of spectrum re-farming are introduced,operators’ spectrum management on the current situation are ananlyzed and summarized to show the positive effect on the development of mobile communication at home and broad.Secondly,the requirement on spectrum resource and the economic benefits of re-farming are analyzed.The theoretical basis on re-farming is introduced from the evolution of wireless technologies standards,limitation of spectral efficiency,characteristics of the electromagnetic spectrum and hybrid networking.Since data services dramatically increase,pressure on spectrum resource is more and more heavy.The FCC model is used to predict the spectrum requirement,the demand for mobile data services,network density,spectral efficiency and current spectrum usage are considerd as the inputs for the model,and then the spectrum requirement is evaluated according to the demand of voice and data services.The indifference curve is introduced to transform the cost of the improvement on network density to economic value for additional spectrum.Compared to traditional construction scheme,the spectrum re-farming plan for LTE-FDD system is proposed to get the specific economic benefits.Next,the deployment strategy of frequency re-farming is discussed.The band allocation,antenna solutions,multi-frequency and multi-mode of mobile terminals and VoLTE services promotion are proposed to implement strategy of frequency re-farming,which theoretically prove the feasibility of this technology.In accordance with the distribution of CDMA carrier frequency,the interference control mechanism is designed,frequency buffer areas are set and the actual test figures are obtained to establish the networking strategy for 800 M LTE frequency re-farming.This strategy ensures high availability of 4G network in rural areas.Finally,the wireless planning platform named Atoll is used to carry on the simulation and optimization in coverage performance for specific 800 M LTE re-farming scheme.Considering the existence characterisitics between CDMA2000 and LTE-FDD system,the simulation project is built by using of 3GPP2 Multi-RAT template,the map import,parameters configuration,the establishment of the traffic map and traffic model are implemented.The Monte Carlo method is used to get the prediction of coverage performance between 800 M LTE system and 1.8G LTE system.Simulation results shows that after frequency re-farming,the 800 M LTE system has improvement in network coverage compared with 1.8G LTE system without regared to switch performance.Then RSRP,margin rate and SINR are used to measure effective coverage performance,and the re-farming LTE nework is optimized through adding sites,the alteration in transmitter antenna diversity and MIMO configuration. |
