Frenquency Planning And Signal Interference In The LTE Planning

Nowadays, with the development of 4G technology, data services are showing explosive development.TD-LTE-Advanced is 4G international standard, which is leaded by our country. It is based on TD-SCDMA of 3G standard and the evolution of the technology.LTE enhance the communication rate by using OFDM and MIMO technology that improve and enhance the air access technology of 3G.From the point of view of technology, OFDM technology as the main characteristics of LTE technology, which of the main idea is to reduce the delay and decrease the impact of interference between symbols. Generally, guard interval is in front of OFDM symbol.When extended protection interval is greater than channel delay, which can eliminate the interference between symbols completely.At the same time, the performance ofthe whole system will have a decisive impact by setting OFDM parameters, such as the cyclic prefix.Cyclic prefix is used to eliminate the interference between symbols. The ability of OFDM systems to resist multipath and to cover is decided by the length of cyclic prefix.Multiple access technology of OFDMA based on OFDM can achieve the orthogonality among users within the cell, which can effectively avoid the interference among the users.It makes the OFDM can achieve a very high capacity.MIMO technology is divided into downlink MIMO and uplink MIMO technology. For a given user beamforming, and guarantee not to interfere or only a very small interference to other users, Spatial multiplexing techniques of downlink MIMO technologymake base station can occupy the same time/frequency resources to different users, The uplink MIMO technology make up the interference minimal between users through the effective match of user pairing,, so as to reduce the internal interference from each cell of the base station.Generally, the LTE downlink adopts OFDMA technology and uplink uses SC-FDMA technology in the LTE system, which can ensure the orthogonality between the symbols and effectively reduce the internal interference in the cell. At the same time it is combined with MIMO technology that effectively reduce the mutual interference of intra cell.LTE system will inevitably lead to the same frequency interference especially in the area of edge, when the LTE system with frequency reuse factor for the network structure of 1 that two district adjacent to use the same frequency band to work in the inter cell(including from the GSM network and TD-SCDMA network). The interference will seriously affect the data rate at the cell edge, so how to avoid the inter cell interference becomes the focus of LTE research.From the current situation of the LTE network, the interference in the LTE system are from LTE internal system and LTE external system(including the operators, folk and electronic equipments and others etc). LTE internal system mainly comes from the interference among the LTE cells.How to locate and solve the problem of interference in TD-LTE internal system(especially the interference from the different frequency of LTE system) quickly, especially interference due to frequency planning in TD-LTE system?I am in charge of project improvement of indoor distribution system and interference investigation and remediation projects in Dongguan Mobile Corporation wireless network optimization center,Ianalysised and summaried GSM network interference and optimization of TD-SCDMA system solutions, which was combined with my own work. I further explored the cause and classification of interference in TD-LTE wireless network through the achievements of interference investigation project and the interference of typical cases in Dongguan mobile corporation. I also summarized the method of TD-LTE interference investigation and investigation process, as well as the solution of interference and the existing problems.I further explore the TD-LTE interference problems of the network frequency planning unreasonable based on TD-LTE interference problems and summaries of the TD-LTE interference to solve problems.I probed the current status of the network frequency planning and future problems as well as TD-LTE system and the GSM system, TD-SCDMA system is long-term coexistence, In frequency planning should pay attention to the problem and I experiment exploration for frequency planning and networking solutions in Dongguan. That will provide reference of subsequent planning and selection of large-scale LTE multi-band hybrid networking scheme and parameter optimization for networking of staff.