Relevant parameters are derived from system messages SIB3, SIB4 and SIB5 of the serving cell. 1.SIB3 contains cell reselection information of the same frequency and different frequency (including inter-RAT). The parameter QHyst is defined in1.1cellreflection info common, which represents the lag effect of the serving cell RSRP, and is used to calculate the formula of the cell reselection ranking r criterion to reduce the reselection oscillation. 1.2 defines snonintrasearch, ThreshServinglow and cellReselectionPriority in cellReselectionServingFreqInfo. 1.2. 1 cell selection priority defines the priority of service frequency reselection in cells with different frequencies, and the value range is 0-7, where 0 represents the lowest priority. The handover of cells with different frequencies is based on the priority value, and the ue will always try to stay in the cell with high priority. Priorities of neighboring cells are broadcast in SIB5. When1.2.2 non-intersearch is used for/off-frequency cell reselection, the threshold parameter for judging whether to perform off-frequency cell reselection measurement. In the case of different frequency reselection, if the priority of the neighboring cell is higher than that of the serving cell, the UE needs to perform different frequency cell reselection measurement. In addition, if the Snonintrasearch parameter is not broadcast in the system message, the UE also needs to perform reselection measurement of different frequency cells. 1.2.3threshServingLow defines the measurement threshold of the serving cell when the UE reselects a cell with a lower priority. In this case, the target cell must also meet a certain measurement threshold. 2. 1 The parameters related to cell reselection in the same frequency are defined in intraFreqCellReselectionInfo. 2.1.1sintrasearch is used as the threshold parameter to judge whether to reselect the same frequency cell. When the S value of the LTE serving cell is less than or equal to Sintrasearch, it is necessary to conduct cell reselection measurement in the same frequency; In addition, if the Sintrasearch parameter is not broadcast in the system message, the same-frequency cell reselection measurement should also be performed. 2. 1.2 In addition, the UE may choose not to perform measurement. T-reflection eutra defines the time interval of cell selection. 2.SIB4 contains cell-related information related to co-frequency cell reselection. 2. 1 defines the cell physical ID list and the corresponding offset value used for the re-selection of the same-frequency cell in the information of neighboring cells in Africa. The offset value 2. 1. 1 is used to calculate the formula of cell reselection ranking r criterion to reduce reselection oscillation. 2. 1.2 also defines the blacklist list of cells in SIB4 that cannot be used for co-frequency reselection. 2. 1.3SIB5 contains cell information related to the reselection of different frequency cells, including the list of different frequency cells, frequencies, etc.