[0033] The embodiment of the present invention describes the processing procedure of the handover failure in the LTE system. For the convenience of expression, the eNodeB used in the LTE system is still called the base station. Handover to a cell under the target base station. The embodiment of the present invention can be understood as: before the user equipment performs handover, the source base station first determines a cell as a backup cell, and includes the backup cell C-RNTI (Cell Radio Network Temporary Identity, Cell Radio Network Temporary Identifier) wireless network The reservation parameters including the temporary identifier are sent to the user equipment, and the user equipment connects with the backup cell according to the reservation parameters of the backup cell after the cell handover fails.
[0034] The specific implementation process of the embodiments of the present invention will be further introduced below with reference to the accompanying drawings.
[0035] see figure 2 shown, figure 2 The process of handling radio link handover failure provided by the first embodiment of the present invention is disclosed. In this embodiment, the target base station and the source base station are the same base station, and the target cell is a cell under the source base station that is different from the source cell. The specific processing flow is as follows:
[0036] Step 202, the source base station determines a cell under its own management as the target cell to be handed over by the user equipment, and determines another cell as a backup cell;
[0037] Step 204, the source base station sends a handover command to the user equipment;
[0038] Step 205, the source base station sends the reservation parameter of the backup cell to the user equipment, and the reservation parameter includes at least the C-RNTI of the backup cell, and may also include the handover start time, target base station (in this embodiment, One or more of the parameters such as the system message block of the source base station);
[0039] Step 206, after receiving the handover command sent by the source base station, the user equipment performs handover to the target cell, and the handover fails;
[0040] Step 207, the user equipment connects with the backup cell according to the reservation parameter of the backup cell.
[0041] Compared with the prior art, in this embodiment, the source base station is responsible for the selection of the backup cell instead of the user equipment, and the backup cell is selected before the handover, instead of starting to select the backup cell after the handover fails, which saves the user equipment. The time spent on cell selection effectively reduces the processing time for radio link failures.
[0042] Before step 202, it can also include:
[0043] Step 201, the user equipment sends a measurement report to the source base station, the measurement report mainly includes the quality parameters of the cell, for example, it may include one or more parameters such as reference signal received power, reference signal received quality, signal-to-noise ratio, etc. It can be other parameters representing cell quality.
[0044] Correspondingly, in step 202, the source base station selects a cell under the source base station as a backup cell according to the measurement report sent by the user equipment and the radio resource management information stored by itself; as for how to determine the target cell, it is a well-known technology in the industry, which is not discussed here. More details.
[0045] After selecting the backup cell, you can further set the access priority of the source cell and the backup cell under the source base station. Usually, the access priority of the backup cell should be set higher than that of the source cell; after setting the source base station After lowering the access priority of the cell, the access priority of the backup cell and the source cell can also be sent to the user equipment. When sending the access priority information, the access priority information can be carried in the handover command. transmission, or adopt other feasible methods. After the handover fails, the user equipment may further determine the backup cell as the preferentially accessed cell according to the access priority.
[0046] Before step 204, it can also include:
[0047] Step 203, a handover negotiation is performed between the source base station and the target cell, and after the handover negotiation is passed, the source base station sends a handover command to the user equipment.
[0048] When sending the reserved parameters of the backup cell, the source base station may use special signaling in step 205 to send the reserved parameters of the backup cell to the user equipment. At this time, steps 204 and 205 may not be restricted in order. , but it must be ensured that the special signaling is received before the user equipment is separated from the source cell; also in step 204, the reserved parameters of the backup cell can be added to the handover command, and the backup cell can be added to the handover command. A handover command to reserve parameters is sent to the user equipment.
[0049] Step 207 may also include a step of judging whether the user equipment has accessed the backup cell within a specified time, for example, when T1 ends, start T2, and judge whether the T2 timer is started during the period from start to end. Complete the access. If the access is not completed when the T2 is terminated, the user equipment enters the RRC idle mode. If the access is completed before the T2 is terminated, step 208 is performed to perform context data and user data between the backup cell and the source cell. transmission.
[0050] The solution provided by the embodiment of the present invention not only saves the time spent by the user equipment on cell selection, but also effectively reduces the processing time of radio link failures, but also because the backup cell and the source cell are under the same base station, context data transmission and user data The transmission is all completed inside the source base station, so the delay of data transmission is also reduced.
[0051] After step 208, step 209 may be further performed: the user equipment sends a message that it has accessed the backup cell to the backup cell.
[0052] Specifically, when judging whether the user equipment has accessed the backup cell within the specified time, the following methods may be used:
[0053] It is judged whether the user equipment has received the uplink configuration and timing advance information sent by the backup cell before the timer T2 expires, and if so, the user equipment has successfully accessed.
[0054] When the user equipment starts to connect with the backup cell according to the reservation parameters of the backup cell, certain conditions need to be met, for example, it is determined that the backup cell satisfies the service type currently performed by the user equipment or the service type The minimum working threshold required by the QoS (Quality of Service) requirements; when the minimum working threshold is not met, if it is determined that the current service is a non-real-time service or the QoS requirements of the current service are determined to be able to tolerate sufficient transmission delay ( The specific delay may depend on factors such as service type, service requirements, etc.), and it is also considered that the conditions are met; if these three conditions are not met, the user equipment considers that it has not accessed the backup cell, and before the timer T2 expires The user equipment directly enters the RRC idle mode.
[0055] see image 3 shown, image 3 The processing flow of the radio link failure in the handover process provided by the second embodiment of the present invention is disclosed. In this embodiment, the target base station and the source base station are not the same base station, and the target cell is a cell under the target base station. The specific processing flow is basically the same as that of the first embodiment, considering that when switching from the source cell to the target cell under the target base station Integrity of data transmission, after steps 304 and 305, step 30a can be added, the source base station sends data to the target base station, correspondingly, after the handover fails in step 306, it also includes step 30b that the source base station stops sending data to the target base station, and steps 30c, the target base station clears the data received from the source base station.
[0056] In the first and second embodiments, when the source base station determines the backup cell, usually the backup cell and the source cell are not the same cell, and the quality of the other cell as the backup cell is higher than that of the source cell, and the user equipment The handover from the source cell is because the quality of the source cell has dropped to a certain extent, or the load of the source cell is too large; then the standby cell may also be the source cell, if there is no more suitable cell than the source cell under the source base station, such as a better quality cell, then you can It is determined that the source cell is the backup cell, or the source cell is directly selected as the backup cell without judging the quality of the cell.
[0057] A. If the source base station determines that the source cell is the backup cell by comparing the quality of each cell, then the source base station also needs to notify the user equipment that the backup cell is the source cell. The specific implementation method can be:
[0058] choose to carry the reservation parameters of the source cell in the handover command; or
[0059] Option to indicate with a specific information element in the handover command, among other possibilities. For example, it is selected that the reservation parameter of the backup cell is not carried in the handover command, so that the user equipment can know that the source cell is the backup cell according to the prior agreement after receiving the handover command.
[0060] B. If the source cell is directly selected as the backup cell without judging the cell quality, then the source base station also needs to notify the user equipment that the backup cell is the source cell. At this time, the source base station can use the method mentioned in A to notify.
[0061] When the user equipment learns that the backup cell is the source cell, regardless of whether the user equipment has received the reservation parameters of the backup cell from the source base station, the user equipment can directly use the reservation parameters of the source cell as the reservation parameters of the backup cell.
[0062] When the backup cell is another cell, if the user equipment fails to handover to the target cell, after connecting to the backup cell, the following steps may be further included:
[0063] detecting whether the user equipment has accessed the backup cell;
[0064] If not, the user equipment connects with the source cell according to the reservation parameter of the source cell saved by itself.
[0065] Further, the following steps may also be included:
[0066] judging whether the user equipment has accessed the source cell;
[0067] If not, after the timer T2 expires, the user equipment enters the RRC idle mode;
[0068] If so, the user equipment notifies the source cell to complete the access.
[0069] When detecting whether the user equipment has accessed the backup cell, the following methods may be used: setting a counter and setting the maximum value of the counter, if the number of times the user equipment attempts to connect reaches the maximum value, it still does not access the backup cell cell, it is considered that there is no access to the backup cell; of course, other feasible methods can also be adopted.
[0070] It should be emphasized here that, for timer T2, if the user equipment does not access the backup cell or the source cell when T2 ends, the user equipment needs to enter the RRC idle mode.
[0071] see Figure 4 shown, Figure 4 The processing flow of the radio link failure in the handover process provided by the third embodiment of the present invention is disclosed. In this embodiment, the backup cell is the source cell, and the target cell is a cell under the source base station that is different from the source cell. The specific operation steps are as follows:
[0072] Step 402, the source base station determines the target base station and the target cell to be handed over by the user equipment, and selects the source cell as a backup cell;
[0073] Step 404, the source base station sends a handover command to the user equipment;
[0074] Step 406, the user equipment performs handover to the target cell after receiving the handover command sent by the source base station, and the handover fails;
[0075] Step 407: After the handover to the target cell fails, the user equipment connects with the source cell according to the parameters of the source cell saved by itself.
[0076] Compared with the first embodiment, since the backup cell itself is the source cell, and the user equipment already knows the parameters of the source cell, the source base station does not need to provide the user equipment with the parameters of the source cell.
[0077] Before step 402, it can also include:
[0078] Step 401, the user equipment sends a measurement report to the source base station.
[0079] Before step 404, it can also include:
[0080] Step 403, a handover negotiation is performed between the source base station and the target cell, and after the handover negotiation is passed, the source base station sends a handover command to the target base station.
[0081] After step 407, it is also possible to determine whether the user equipment has accessed the backup cell within the specified time, for example, whether the access is completed within the period from the start of the T2 timer to the termination of the timer, if not, the user equipment enters the RRC idle mode, If it is, step 409 is performed: the user equipment sends a message that it has accessed the source cell to the source cell.
[0082] Specifically, when judging whether the user equipment has accessed the source cell within the specified time, the following methods may be used:
[0083] Start the timer T2; determine whether the user equipment has received the uplink configuration and timing advance information sent by the source cell before the timer T2 expires, and if so, the user equipment has successfully accessed.
[0084] When the user equipment starts to connect with the source cell according to the reservation parameters of the source cell, certain conditions need to be met, for example, it is determined that the source cell satisfies the service type currently performed by the user equipment or the service type The minimum working threshold required by the QoS (Quality of Service) requirements; when the minimum working threshold is not met, if it is determined that the current service is a non-real-time service or the QoS requirements of the current service are determined to be able to tolerate sufficient transmission delay ( The specific delay may depend on factors such as service type, service requirements, etc.), and it is also considered that the conditions are met; if these three conditions are not met, the user equipment considers that it has not accessed the backup cell, and before the timer T2 expires The user equipment directly enters the RRC idle mode.
[0085] see Figure 5 shown, Figure 5 The processing flow of the radio link failure in the handover process provided by the fourth embodiment of the present invention is disclosed. In this embodiment, the backup cell is the source cell, and the target cell is the target cell under the target base station. The specific processing flow is generally the same as that of the third embodiment. The same, with the addition of step 50a, the source base station sends data to the target base station, correspondingly after the handover failure in step 506, it also includes step 50b that the source base station stops sending data to the target base station, and step 50c, the target base station clears the data received from the source base station. The data.
[0086] Although the above embodiment only takes the handover failure inside the LTE system as an example for description, the method provided by the embodiment of the present invention is also applicable to the situation of the handover failure from the LTE system to other systems such as GSM, UTRAN, etc., and is even applicable to Handover failure to other non-2G/3G systems, such as WLAN. Because no matter which system the handover is to, after the handover fails, the user equipment only contacts the backup cell under the source base station, and does not require the participation of entities of other systems. Specifically, when handing over within the LTE system, the handover target is the target cell under the target base station (eNodeB). When handing over to the GSM system, the handover target is the target cell under the target base station (BTS, Base Transceiver Station). When handing over to the UMTS system , the handover target is the target cell under the target base station (NodeB), and when switching to the WLAN, the handover target is an access point (AP, Access Point). As for how to determine the switching target, it can be decided according to the specific situation of each system.
[0087] see Image 6 shown, Image 6 A base station provided by an embodiment of the present invention is disclosed, which specifically includes:
[0088] A selection unit 62, configured to select a cell under the management of the base station as a backup cell
[0089] A sending unit 63, configured to send the switching command to the user equipment;
[0090] The notification unit 64 is configured to notify the user equipment that the backup cell is the source cell or notify the user equipment of the reserved parameters of the backup cell when the selection unit 62 selects the source cell as the backup cell; and the selection unit 62 selects When other cells serve as backup cells, notify the user equipment of the reserved parameters of the backup cell and the reserved parameters of the backup cell
[0091] A connection establishing unit 65, configured to establish a connection between the user equipment and the backup cell after the handover of the user equipment to the handover target fails. .
[0092] In addition, a receiving unit 61 may also be included, configured to receive the measurement report sent by the user equipment and send it to the selection unit 62; the selection unit 62 selects the measurement report under the source base station according to the measurement report sent by the user equipment and the radio resource management information. One cell acts as a backup cell;
[0093] The selection unit 62 specifically includes:
[0094] The obtaining unit 621 is configured to obtain radio resource management information and the measurement report sent by the user equipment received by the receiving unit 61;
[0095] The processing unit 622 is configured to determine a cell under the management of the base station as a backup cell according to the radio resource management information and the measurement report.
[0096] When the user equipment is handed over within the LTE system, the handover target is specifically the target cell under the target base station, and when it is handed over to the WLAN, the handover target is specifically the access point.
[0097] In addition, the present invention also provides a user equipment, specifically including:
[0098] a receiving unit, configured to receive a handover command sent by the base station, where the handover command includes a handover target;
[0099] An acquisition unit, configured to acquire the reserved parameters about the backup cell sent by the base station; or use the reserved parameters of the source cell as the parameters of the backup cell after the base station notifies that the backup cell is the source cell;
[0100] a first communication unit, configured to establish a connection with the switching target;
[0101] a judging unit, configured to judge whether the first communication unit has established a connection relationship with the handover target;
[0102] The second communication unit is configured to establish a connection with the backup cell according to the parameters of the backup cell when the result of the judging unit is negative.
[0103] In addition, the user equipment may further include a notification unit, configured to notify the backup cell that access has been completed after the second communication unit establishes a connection with the backup cell.
[0104] The method and device provided by the embodiments of the present invention save the time spent by the user equipment on cell selection after the handover of the user equipment fails, not only effectively reduces the processing time of radio link failure, but also does not increase the complexity of the existing system , in addition, because the backup cell and the source cell are under the same base station, context data transmission and user data transmission are all completed inside the source base station, thus reducing the delay of data transmission. In addition, the method and device provided by the embodiments of the present invention have a wide range of applications, and are applicable not only to the processing after the handover failure within the LTE system, but also to the processing after the handover failure from the LTE system to other systems.
[0105] The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.
