In the analysis of call failure events, it is found that many call failure reasons are due to the failure of the caller or the called user’s Rab assignment. This phenomenon has no regularity, resulting in low CS connection rate. Through the analysis and positioning of this problem, this paper summarizes the 1 bit rewrite fault of DSP, and can be widely applied to similar fault detection in the existing network. In the operation of the current network, the test found that many call failure events were caused by the failure of the calling or called user Rab assignment. The reason value of 214 showed that the requested circuit/channel was not available. This phenomenon has no regularity, resulting in low CS connection rate. Through the analysis and positioning of this problem, this paper summarizes the 1 bit rewrite fault of DSP, thermostatic element and can be widely applied to similar fault detection in the existing network. This paper mainly uses the methods of signal tracking and DSP memory viewing to locate and analyze a large number of abnormal events when the caller or called user Rab assignment fails. Finally, through step-by-step troubleshooting, the overall and complete troubleshooting ideas aiming at such characteristics are given, which can well guide the specific fault analysis and location. In IU-PS, RNC is connected to SGSN. User surface and STCP coupling address are synthesized on SGSN. In IU-CS, RNC connects MGW and MSCERVER, assigns user face addresses on MGW and STCP coupling addresses on MSCERVER. In data planning, if both RNC IU-CS and IU-PS adopt IP networking, the User-face addresses allocated to RPU in the previous IU-PS share.
Network appearance and logo fields are shared.
In data configuration, IU-CS has one more transmission path configuration than IU-PS, one path group per GIPI board. The Iu UP initialization process between RNC and MGW fails sometimes, which results in unsuccessful calls on the existing network.
In the process of failure, the response message sent by MGW to RNC indicates that the failure reason is Iu UP Mode version not supported. The message with the message direction of “RECV” in the figure above is the initial message sent by RNC to MGW; the message with the message direction of “SEND” is the response message returned by MGW to RNC. Due to the different input messages RNC sends to MGW, the different responses of MGW to the initialization process of Iu UP are caused. Whereas headerCRC and payload CRC do not affect the parsing of message structure, TI will affect the parsing of message structure.
If TI indicates “ipti Present”, indicating that cell IPTI is carried in this message, MGW will parse IPTI value at the relevant place of this message according to the definition of message structure defined by the protocol; if it indicates “ipti Absent” at that place, it indicates that IPTI value is present.
The message does not contain the cell IPTI. MGW skips parsing the IPTI value and parses the data from the relevant place into the next cell. Therefore, in the failed initialization process, TI in the message sent by RNC to MGW is 0, indicating that this message does not carry IPTI value. Normally, the IPTI value should not be carried in the message, that is, the second half of the message data should be different from the message indicating that IPTI (TI 1) is carried. However, you can see that the latter half of the message has exactly the same data as the message indicating that IPTI (TI 1) is carried. This results in MGW parsing messages by parsing the IPTI part that should not be carried into its next neighbor cell, i.e.
Iu UP Mode Versions support. As shown in the following figure, when TI = 1, 0X11 is parsed as IPTI, which is ox00 03; when TI = 0, IPTI is NULL, which is parsed as 0x1100, while 0x1100 is an illegal value, so the reason for MGW return error is Iu UP Mode version not supported. In summary, the root cause of the problem is that the message sent by RNC is illegal and does not conform to the 25.415 protocol. It is necessary to check and analyze the status of the DSP of each RUB veneer in RNC. RNC side analysis locates the IU UP initialization failure due to abnormal rewriting of specific DSP memory. Iu UP initialization failed, IUUP has the same configuration parameters, IPTI has been filled in, TI sometimes does not, see the problem of signaling internal media IP address fixed Usr_UcpmcUp_Message.ptSUciuInstSetupResp.tUciuIpAddress.data = 7F D8 C7 D4, related to specific DSP, suspected that the DSP code segment rewriting. If there is an exception notification message, the network management will display an exception notification message with SLAVE soft check. Detailed information includes abnormal notification of RUB single board slot, DSP number information, according to the details of the fault DSP can be found.
For the operation of blocking fault DSP, network management does not report the alarm, but the service will not accept the DSP. Ji Li, male, Beijing Communication Planning and Design Institute of Putian Information Industry, China, Engineer, Research Direction: TDD Wireless Network.
Song Jing, male, Beijing Communication Planning and Design Institute of Putian Information Industry, China, Engineer, Research Direction: TDD Wireless Network.