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By reading system information, MS can access the network, perform cell selection and reselection, fully utilize various services provided by the network, and achieve favorable cooperation with the network. SYS INFO can be divided into two parts:SYS INFO sent on BCCH, including SYS INFO 1, 2, 2BIS, 2TER, 3, and 4, which are used by MS in idle mode.SYS INFO sent on SACCH, including system information 5, 5BIS, 5TER, and 6, which are used by MS in dedicated mode. Additionally Huawei BSC supports the system information 7 and 13 to support GPRS. BCCH system information belongs to common channel information. SACCH system information basically belongs to TRX management information. Common channel and TRX management information should be selected in order to observe all the system information when tracing on the layer 3 messages of radio interface.Version G2BSC32.10100.03.0520B and later, the system information 1, 2, 2TER, 3, 4, 5, 5TER, and 6 are default system information to be transmitted to cells. System information 2BIS and 5BIS are conditionally transmitted on GSM1800 cells. It will be explained in the following section.The maximum number of cell frequencies configured in CA(Cell Allocation) is 64. Due to the restriction of cell channel description format, the frequencies of a cell cannot be configured unlimitedly. The formats of cell channel description are determined respectively by Cell Channel Descriptions second byte Format ID (bit8, bit7, bit4, bit3, bit2).
These parameters will be explained in the following sections.Neighbor cell description describes all the neighbor cells BCCH ARFCNs. Currently, Huawei supports 32 neighbor cells at most. Except the fifth bit (BA_IND) and sixth bit (EXT_IND) of the second byte, the coding format of neighbor cell description is the same as cell channel description.Extended indication (EXT_IND) is transmitted in system information 2 and 5. It indicates whether there are BCCH frequencies of neighbor cell transmitted in system information 2BIS and 5BIS. It has one bit. If it is set to 0, this indicates system information 2 and 5 have carried all the BCCH frequencies (the same band as serving cells )in the BA table. If it is 1, it means system information 2 and 5 carries only part of the content of BA table.BA table indication (BA_IND) is transmitted in system information 2 and 5. It has one bit and it is used to tell the MS to decide whether to use the data of BA1 or BA2 table. In other words, if the current neighbor cell relationship and BA2 table are modified during the conversation of MS, BA_IND in system information 5 will be set to 1 instead of 0. It instructs MS to re-decode the neighbor cell frequency shown in the system information 5 (maybe also 5BIS and 5TER) to get the latest information.Network Color Code Permitted (NCC Permitted) is transmitted on system information 2 and 6. It has eight bits.The eight bits are used to show if the particular NCC codes are permitted for the MS to access. If bit N is set to 0 (0
