CN103763730B - Wireless link failure recovery enhancing method and system based on optimal reconstruction target cell selection - Google Patents

Abstract

The invention discloses a radio link failure restoration enhancement method and device based on optimal reconstruction target cell selection, and belongs to the technical field of mobile communication. In this method, the first predicted target cell and the second predicted target cell are determined according to the RSRP gradient values of each adjacent base station obtained through continuous measurement and calculation; the prepared cell is obtained according to the handover instruction of the serving base station; based on the prepared cell base station and the mobile The proximity of the path sorts the prepared cell list by priority; the T310 timer is terminated early based on the handover execution event. This method improves the same probability and spectrum utilization rate of the predicted target cell and the target cell, reduces network signaling overhead, and optimizes the signaling process; at the same time, it improves the query efficiency of the RRC connection reconstruction target cell in the prepared cell list, that is, improves Increased rebuild success rate and reduced outage time.

Description

A radio link failure recovery enhancement method based on optimal reconstruction target cell selection and system

technical field

The invention belongs to the technical field of mobile communication, and relates to a radio link failure restoration enhancement method and device based on the selection of the best reconstruction target cell.

Background technique

To adapt to the rapidly growing mobile data traffic, operators have deployed more infrastructure to bring cellular networks closer to UEs, thereby increasing spectrum efficiency and spatial reuse. Faced with this situation, the 3GPP organization proposed a heterogeneous small cell network composed of macro cells and low-power nodes (such as picocells, femtocells, relaynodes). However, according to the simulation results of mobile robustness in heterogeneous small cell networks proposed by 3GPPRAN2, the handover performance in heterogeneous networks is far from that of traditional homogeneous networks. The handover failure rate HOF and the ping-pong handover rate Ping -pong greatly increased. The simulation results also show the radio link failure rate RLF of mobile users in the heterogeneous small cell network. The analysis shows that a large number of handover failures HOF lead to a large number of radio link failure RLF. In addition, the analysis was performed on the UE (User Equipment) in the high-speed mobile state, and it was found that the handover performance of the high-speed UE in the heterogeneous network is very poor, and it is easy to cause RLF. Even if it can find a suitable cell for RLF recovery, the It will cause a lot of service interruption time and extra signaling transmission. Therefore, RLF recovery enhancement is put on the agenda, hoping to find a suitable method to further reduce the occurrence probability of RLF, and minimize the service interruption time during the RLF recovery process.

The prior art proposes a method of "selecting multiple reserve cells for the UE in advance". The main idea of this method is that, before the handover occurs, the base station of the current serving cell of the mobile user equipment selects a plurality of reserve cells for the UE in advance according to a predictive trigger mechanism of a reserve cell, requests these reserve cells to prepare for the handover of the UE, and The system information, RRC level configuration information and designated bearer information of these prepared cells are notified to the UE in advance through additional signaling.

The prediction trigger mechanism of the existing reserve cell is: when the UE measures that the signal strength of a certain cell is higher than a certain threshold value, or lower than the signal strength of the current serving cell of the UE, but the difference is smaller than a certain threshold value, the The cell is determined as a reserve cell.

There are many defects in the existing reserve cell prediction trigger mechanism and reserve cell selection criteria, because when the UE is moving at the edge of the cell, if the reserve cell is selected based on the signal strength being higher than a certain threshold value, the selected reserve cell is very difficult. It may not be the neighboring cell that the UE is about to move into, but just the nearest neighboring cell on the left and right sides of the UE's current location. Therefore, the selection success rate of the reserve cell in the prior art is low, which leads to unnecessary resource reservation behavior and reduces spectrum utilization. At the same time, after the reserve cell is determined, additional signaling needs to be used to inform the UE of the information of the reserve cell, which also greatly increases network signaling overhead.

In the prior art, a fast reconstruction method in case of handover failure is also proposed—shortening the T310 timer. The main idea of this method is that the handover failure HOF in the heterogeneous network mostly occurs in the handover preparation stage, the main reason is that the transmission of the handover command fails, and the failure rate of the handover measurement report is low. Therefore, the target cell may already be ready for UE access. Then, for the UE, it is unnecessary to trigger the RRC reconnection to the target base station until T310 times out. Therefore, before the UE triggers the RRC re-establishment process with the optimal cell, a shorter RLF timer T310 is used to enable the UE to trigger the RRC re-establishment faster and reduce user data interruption time. This technology can neither guarantee that the target cell has prepared the context of the UE, nor can it guarantee that the prepared cell selected by the UE is a suitable cell.

Contents of the invention

In view of this, the object of the present invention is to provide a method and device for enhancing radio link failure recovery based on the selection of the best reconstruction target cell.

To achieve the above object, the present invention provides the following technical solutions:

A wireless link failure recovery enhancement method based on the selection of the best reconstruction target cell, comprising the following steps: 1) The current serving base station of the mobile terminal continuously obtains the measurement of the signal quality of the base station by the mobile terminal, and analyzes whether the mobile terminal needs to start Execute the handover measurement of adjacent base stations, if necessary, perform step 2); if not, continue to perform step 1); 2) The mobile terminal continuously obtains the measured values of RSRP for all adjacent base stations; 3) After completing the phase During the nth RSRP measurement of the neighboring base station, obtain and record the RSRP gradient value Gradient _n-1,n (n=2,3,4,...) ; 4) According to the signal quality of the current serving base station of the mobile terminal, judge whether it is possible to start predicting the target cell, if yes, perform step 5); if not, perform step 2); , obtain the cell identity of the largest RSRP gradient cell and the second largest RSRP gradient cell; 6) determine the cell identity of the first predicted target cell and the second predicted target cell according to the cell identity of the largest RSRP gradient cell and the second largest RSRP gradient cell; 7) Obtain the current moving speed of the mobile terminal; 8) According to the current moving speed of the mobile terminal, obtain an early handover preparation trigger event EarlyPreparEvent; 9) When the early handover preparation trigger event EarlyPreparEvent is satisfied, the mobile terminal sends a message to the current serving cell The base station sends an early handover preparation indication Early_HO_Prepar_IND, which carries the cell identities of the first predicted target cell and the second predicted target cell, so that the base station of the current serving cell can The cell identity and the predicted target cell perform an early handover preparation operation; 10) receive an early handover instruction Early_HO_CMD, which carries the cell identity of the prepared cell that has been prepared; 11) obtain the priority of the prepared cell, generate and Backup prepared cell list Prepared-cell_list; 12) Acquire handover execution event ExeEvent according to the current moving speed of the mobile terminal; 13) When the handover execution event ExeEvent is satisfied, terminate T310 timer in advance based on ExeEvent and declare RLF; 14) When the cell identity of the target cell meeting the Exe Event is the same as the cell identity of the prepared cell in the Prepared-cell_list, select the target cell with the same identity in the Prepared-cell_list for RRC connection re-establishment; 15) in the cell of the target cell satisfying the ExeEvent When the ID is different from the cell ID of the prepared cell in the Prepared-cell_list, the

The cells in the Prepared-cell_list search for a suitable cell in order of priority from high to low for RRC connection re-establishment.

Further, the mobile terminal continuously acquires the RSRP measurement values of all neighboring base stations, specifically including: the mobile terminal is located in a radio link failure RLF frequent area; the radio link failure RLF frequent area is composed of a macrocell and Several microcell picocells provide wireless communication services; the current access base station of the mobile terminal is a microcell base station PeNB covered by a macrocell; the adjacent base station can be a macrocell base station MeNB covering a serving microcell, or is the adjacent micro cell base station PeNB.

Further, in step 3), when the nth RSRP measurement of the adjacent base station is completed, the RSRP gradient values of all the adjacent base stations from the n-1th to the nth measurement are obtained and recorded, specifically including: During the nth RSRP measurement of the adjacent base station, obtain the RSRP measurement value of the mobile terminal for the n-1th time to all the adjacent base stations; obtain the RSRP of the mobile terminal for the nth time to all the adjacent base stations Measured value; according to the n-1th measured value, the n-th measured value and the RSRP measurement interval Δt, the RSRP gradient values Gradientn-1,n (n=2,3,4,n=2,3,4, ...); Determine the information table containing the corresponding cell IDs of all neighboring base stations and their RSRP change gradient values Gradientn-1,n (n=2,3,4,...) as the RSRP gradient table; The RSRP gradient value Gradientn-1,n (n=2,3,4,...) of the base station is recorded in the RSRP gradient table.

Further, in step 5), when the target cell prediction event is met, obtain the cell identifiers of the largest RSRP gradient cell and the next largest RSRP gradient cell, specifically including: querying the RSRP gradient table, and obtaining the largest RSRP gradient value recorded each time The two gradient values correspond to the cell ID1 _n-1,n and ID2 _n-1,n of the cell; query all ID1 _n-1,n , filter out the cell ID ID1 with the most occurrences, and determine ID1 as the maximum RSRP The cell ID of the gradient cell; query all ID2 _n-1,n , filter out the cell ID ID2 with the most occurrences, and determine ID2 as the cell ID of the next largest RSRP gradient cell.

Further, in step 6), the cell identities of the first predicted target cell and the second predicted target cell are determined according to the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient, specifically including: determining the cell identities of the cell with the largest RSRP gradient is the cell identity of the first predicted target cell; and determines the cell identity of the second largest RSRP gradient cell as the cell identity of the second predicted target cell.

Further, according to the current moving speed of the mobile terminal, obtaining an early handover preparation trigger event EarlyPrepar Event specifically includes: obtaining the current moving speed of the mobile terminal; querying the moving speed v-EarlyPreparEvent mapping table, and according to the mobile terminal's moving Acquire the corresponding EarlyPreparEvent for speed; set the EarlyPrepar Event as an A3 event with a smaller offset value (TTT=0ms).

Further, in step 11), the priority of the prepared cells is obtained, and a list of prepared cells is generated and backed up

Prepared-cell_list specifically includes: querying the RSRP gradient table to obtain the latest RSRP gradient value of the prepared cell; determining the priority of the prepared cell with the largest latest RSRP gradient value as 1; setting the priority of the prepared cell with the second largest latest RSRP gradient value The priority of the prepared cell is determined to be 2; according to the cell identifier and priority of the prepared cell, a list of prepared cells Prepared-cell_list is generated and backed up.

Further, according to the current moving speed of the mobile terminal, obtaining the handover execution event ExeEvent specifically includes: obtaining the current moving speed of the mobile terminal; querying the moving speed v-ExeEvent mapping table, and obtaining the corresponding event according to the moving speed of the mobile terminal. ExeEvent; determine the A3 event (TTT=0ms) with a larger offset value as the switching execution event ExeEvent.

Further, according to the cell identities of the first predicted target cell and the second predicted target cell, send an early handover preparation request signaling Early_HO_Prepar_Request to the first predicted target cell and the second predicted target cell, and obtain the first predicted target cell and the second predicted target cell. The channel resource of the second predicted target cell; when receiving the early handover preparation acknowledgment signaling from the predicted target cell, determine the cell identity carried in the early handover preparation confirmation signal Early_HO_Prepar_ACK as the cell identity of the prepared cell; The mobile terminal sends a handover command HO_CMD, and the handover command carries the cell identifier of the prepared cell.

The present invention also provides a radio link failure recovery enhancement device based on the selection of the best reconstruction target cell, including a mobile terminal and a base station;

The mobile terminal includes: an RSRP storage unit, configured to continuously acquire RSRP measurement values of all neighboring base stations;

The RSRP gradient storage unit is used to calculate the RSRP gradient value and store the RSRP gradient table; the first acquisition unit is used to obtain the cell identification of the largest RSRP gradient community and the second largest RSRP gradient community; the first determination unit is used to determine the first The cell identity of the predicted target cell and the second predicted target cell; the second obtaining unit is used to obtain the current moving speed of the mobile terminal; the third obtaining unit is used to obtain the early handover according to the current moving speed of the mobile terminal The early preparation trigger event EarlyPreparEvent; the Early_HO_Prepar_IND sending unit is used to send an early handover preparation indication, and the early handover preparation indication carries the cell identities of the first predicted target cell and the second predicted target cell, so that the base station of the current serving cell can A predicted target cell and the cell identity of the second predicted target cell and the predicted target cell perform an early handover preparation operation; an Early_HO_CMD receiving unit is used to receive an early handover command Early_HO_CMD, and the early handover command carries the prepared cell Cell ID; the prepared cell information storage unit is used to generate and back up the prepared cell list Prepared-cell_list; the fourth acquisition unit is used to obtain the handover execution event ExeEvent according to the current moving speed of the mobile terminal; T310 terminates the trigger in advance A unit for terminating the T310 timer early based on the ExeEvent and declaring RLF when the handover execution event ExeEvent is satisfied;

The base station includes: an Early_HO_Prepar_IND receiving unit, configured to receive an early handover preparation indication, where the early handover preparation indication carries the cell identities of the first predicted target cell and the second predicted target cell; an early handover preparation execution unit, configured to perform according to the first A cell identifier of a predicted target cell and a cell identifier of a second predicted target cell, performing an early handover preparation operation with the first predicted target cell and the second predicted target cell; an Early_HO_Prepar_Request sending unit, configured to send an early handover preparation request signaling the Early_HO_Prepar_ACK receiving unit is used to receive the early handover preparation request confirmation signaling; the Early_HO_CMD sending unit is used to send the early handover command Early_HO_CMD, and the early handover command carries the cell identity of the prepared cell.

The beneficial effects of the present invention are:

1. The mobile terminal calculates the RSRP change gradient value based on continuous measurement of the Reference Signal Received Power (RSRP) of all adjacent base stations, and then determines the corresponding cells of the two base stations with the largest RSRP change gradient values as the first prediction target cell and the second prediction target cell target area. Compared with the prior art, in the selection of the predicted target cell, the signal quality is used as the selection basis, and the present invention is more accurate in selecting the predicted target cell that the UE will likely move into, especially for users who are moving at the edge of the cell. The probability that the predicted target cell is the same as the target cell can be improved, unnecessary resource reservation operations can be reduced, and spectrum utilization can be improved. At the same time, the success rate of RRC reconstruction of the mobile terminal is also improved.

2. After triggering and predicting the advance handover preparation operation of the target cell based on the advance handover preparation event, the serving base station informs the UE that the cell has been prepared through a handover instruction. Compared with the prior art because the handover preparation operation is not triggered based on the handover measurement event and requires additional signaling to inform the UE that the cell is prepared, the handover instruction is used to inform the UE that the cell is prepared, which can reduce unnecessary network signaling overhead. Optimize the handover signaling process.

3. The mobile terminal sorts the prepared cells in the prepared cell list Prepared-cell_list according to the priority based on the proximity between the base stations of the prepared cells and the moving path. Compared with inquiring suitable target cells suitable for reestablishing RRC connection in the list of prepared cells in the prior art, the present invention has higher efficiency in the query process and shortens the interruption time.

4. The mobile terminal terminates the T310 timer in advance based on the handover execution event. Compared with the shortened T310 timer used in the prior art, the present invention is more reasonable in the selection of the duration of the T310 timer. Since the UE has already sent the MR measurement report to the source base station when the A3 event is triggered. Therefore, it can simultaneously ensure that the target cell has prepared the UE context and that the prepared cell selected by the UE is a suitable cell, which improves the success rate of re-establishment and shortens the interruption time.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Fig. 1 is the flowchart of the first embodiment of the RLF recovery enhancement method provided by the present invention;

Fig. 2 provides for the RSRP gradient value Gradient _n-1,n obtained and recorded from the n-1 to the n-th measurement of all adjacent cells when completing the n-th RSRP measurement of the adjacent cells provided by the present invention (n=2,3,4,...) the flowchart of the first embodiment of the method;

Fig. 3 is a flow chart of the first embodiment of the method for obtaining the cell identifiers of the largest RSRP gradient cell and the second largest RSRP gradient cell when the target cell prediction event is met according to an embodiment of the present invention;

4 is a flow chart of a first embodiment of the method for determining the cell identities of the first predicted target cell and the second predicted target cell according to the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient provided by an embodiment of the present invention;

FIG. 5 is a flow chart of a first embodiment of a method for obtaining an early handover preparation trigger event EarlyPreparEvent according to the current moving speed of the mobile terminal provided by an embodiment of the present invention;

Fig. 6 is the flowchart of the first embodiment of the method for obtaining the priority of the prepared cell and generating the prepared cell list Prepared-cell_list;

FIG. 7 is a flowchart of a first embodiment of a method for acquiring a handover execution event ExeEvent according to the current moving speed of the mobile terminal;

FIG. 8 is a flow chart of the second embodiment of the RLF recovery enhancement method in the embodiment of the present invention;

FIG. 9 is a schematic diagram of the movement path and cell deployment of the mobile terminal in this application scenario;

FIG. 10 is a schematic diagram of RSRP gradient analysis of neighboring base stations in this application scenario;

FIG. 11 is a flow chart of handover signaling in an embodiment of the present invention;

FIG. 12 is a schematic diagram of a delay analysis of RLF recovery of a radio link failure in an embodiment of the present invention;

FIG. 13 is a schematic diagram of a mobile terminal provided by an embodiment of the present invention;

FIG. 14 is a schematic diagram of a base station provided by an embodiment of the present invention.

detailed description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a flow chart of the first embodiment of the RLF fast recovery method provided by the present invention. In this embodiment, the mobile terminal is located in a radio link failure RLF-prone area. In the radio link failure RLF frequent area, a macro cell macrocell and several micro cells picocells provide wireless communication services. The current access cell of the mobile terminal is a picocell under the coverage of the macro cell.

The process for the mobile terminal to apply the RLF recovery enhancement method during the movement may specifically include:

Step A1, the current serving base station of the mobile terminal continuously obtains the signal quality measurement of the mobile terminal to the base station, and analyzes whether the mobile terminal needs to start performing handover measurement on neighboring base stations. If necessary, go to step A2. If not, continue to step A1.

Step A2, the mobile terminal continuously acquires the RSRP measurement values of all neighboring base stations.

Specifically, the mobile terminal may continuously acquire RSRP measurement values of all neighboring base stations. All the adjacent base stations include the adjacent micro cell base station PeNB near the serving micro cell and the macro cell base station MeNB covering the serving micro cell.

Step A3, when completing the nth RSRP measurement of the adjacent base stations, obtain and record the RSRP gradient values Gradient _n-1,n (n=2) of the n-1th to nth measurements of all adjacent base stations ,3,4,...).

Specifically, the mobile terminal may acquire and record the RSRP gradient values Gradient _n-1,n ( n=2,3,4,...). Wherein, the information table recording the corresponding cell IDs of all neighboring base stations and their RSRP change gradient values Gradient_ID _n-1,n (n=2,3,4,...) is determined as the RSRP gradient table.

Step A4. According to the signal quality of the current serving cell of the mobile terminal, it is judged whether it is possible to start predicting the target cell. If possible, go to step A5. If not, go to step A2.

Specifically, the mobile terminal may determine whether to start predicting the target cell according to the signal quality of the current serving cell of the mobile terminal. If possible, go to step A5. If not, continue to step A2.

Step A5, when the predicted event of the target cell is satisfied, obtain the cell identities of the cell with the largest RSRP gradient and the cell with the next largest RSRP gradient.

Specifically, when the target cell prediction event is met, the mobile terminal may query the RSRP gradient table to obtain the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient. Wherein, the cell identifier of the cell with the largest RSRP gradient refers to the cell identifier with the largest RSRP gradient value and the most times in all records. The cell ID of the cell with the second largest RSRP gradient refers to the ID of the cell with the second largest RSRP gradient value and the most times in all records.

Step A6: Determine the cell identities of the first predicted target cell and the second predicted target cell according to the cell identities of the cell with the largest RSRP gradient and the cell with the next largest RSRP gradient.

Specifically, the mobile terminal may determine the cell identities of the first predicted target cell and the second predicted target cell according to the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient. Wherein, the cell identity of the cell with the largest RSRP gradient is determined as the cell identity of the first predicted target cell, and the cell identity of the cell with the next largest RSRP gradient is determined as the cell identity of the second predicted target cell.

Step A7, obtaining the current moving speed of the mobile terminal.

Specifically, the mobile terminal can obtain the current moving speed when moving, and the moving speed can be obtained by the high-speed mobile vehicle where the mobile terminal is located, and then sent to the mobile terminal.

Step A8, according to the current moving speed of the mobile terminal, acquire an early handover preparation trigger event EarlyPreparEvent.

Specifically, the mobile terminal may acquire an early handover preparation trigger event EarlyPreparEvent according to the current moving speed of the mobile terminal. Wherein, the mobile terminal can query the v-EarlyPreparEvent mapping table to obtain an early handover preparation trigger event matching the current moving speed.

The exemplary structure of the v-EarlyPreparEvent mapping table is shown in Table 1:

Table 1. v-EarlyPreparEvent mapping table

V EarlyPreparEvent(A3eventwithTTT=0ms) low speed 2dB medium speed 1.5dB high speed -1dB

Step A9: When the early handover preparation trigger event EarlyPreparEvent is satisfied, the mobile terminal sends an early handover preparation indication Early_HO_Prepar_IND to the base station of the current serving cell, and the handover preparation indication carries the first predicted target cell and the second predicted target cell The cell identity of the current serving cell, so that the base station of the current serving cell performs handover preparation operations in advance according to the cell identity of the first predicted target cell and the second predicted target cell and the predicted target cell.

Specifically, the mobile terminal may send an early handover preparation indication Early_HO_Prepar_IND to the base station of the current serving cell when the early handover preparation trigger event EarlyPreparEvent is satisfied, and the handover preparation indication includes the first predicted target cell and the second Predicting the cell identity of the target cell, so that the base station of the current serving cell performs an advance handover preparation operation according to the cell identity of the first predicted target cell and the second predicted target cell and the predicted target cell.

Step A10, receiving an early handover command Early_HO_CMD, the early handover command carrying cell identifiers of prepared cells.

Specifically, the mobile terminal may receive an early handover command Early_HO_CMD, where the early handover command carries cell identities of prepared cells. Wherein, after receiving the Early_HO_CMD, the mobile terminal does not execute the handover immediately, but continues to measure the radio signal environment, and when the handover execution event is satisfied, selects a best cell at an optimal time for handover.

Step A11, obtaining the priority of the prepared cells, generating and backing up the list of prepared cells Prepared-cell_list.

Specifically, the mobile terminal may obtain the priority of the prepared cells, generate and back up the Prepared-cell_list list of prepared cells. After the RLF, the mobile terminal can query the cells suitable for RRC connection reestablishment in the Prepared-cell_list in order according to the priority, so as to improve the efficiency of selecting a suitable cell and shorten the interruption time. Wherein, the priority of the prepared cell is determined according to the proximity between the base station of the prepared target cell and the moving path. The higher the proximity, the higher the priority.

Step A12, according to the current moving speed of the mobile terminal, acquire the handover execution event ExeEvent.

Specifically, the mobile terminal may acquire the handover execution event ExeEvent according to the current moving speed of the mobile terminal. Wherein, the mobile terminal can query the v-ExeEvent mapping table to obtain the handover execution event ExeEvent matching the current moving speed.

The exemplary structure of the v-ExeEvent mapping table is shown in Table 2:

Table 2. v-ExeEvent mapping table

V ExeEvent(A3eventwithTTT=0ms) low speed 2.5dB medium speed 2.5dB high speed 2dB

Step A13, when the handover execution event ExeEvent is satisfied, prematurely terminate the T310 timer based on the ExeEvent and declare RLF.

Specifically, when the handover execution event ExeEvent is satisfied, the mobile terminal may prematurely terminate the T310 timer based on the ExeEvent and declare the RLF. Wherein, the embodiment of the present invention discusses the recovery enhancement of RLF, so only discusses the situation that T310 has started counting when the handover execution event ExeEvent is satisfied. The case where T310 does not start timing when the handover execution event ExeEvent is satisfied will not be discussed.

Step A14, when the cell identity of the target cell meeting the ExeEvent is the same as the cell identity of the prepared cell in the Prepared-cell_list, the mobile terminal selects the target cell with the same identity in the Prepared-cell_list for RRC connection reestablishment.

Step A15. When the cell identity of the target cell satisfying the ExeEvent is different from the cell identity of the prepared cell in the Prepared-cell_list, the mobile terminal searches for a suitable cell in the order of priority from high to low to perform RRC on the cells in the Prepared-cell_list The connection is reestablished.

Fig. 2 is when the nth RSRP measurement to the adjacent cell is completed, the RSRP gradient value Gradient _{n-1, n} (n=2) obtained and recorded from the n-1th to the nth measurement of all the adjacent cells , 3, 4, ...) is a flow chart of the first embodiment of the method. In this embodiment, when the mobile terminal completes the nth RSRP measurement of the adjacent cells, it acquires and records the RSRP gradient values Gradient _{n-1 of the n-1 to nth measurements of all adjacent cells,} The steps for _n (n=2,3,4,…) (step A3) specifically include:

Step B1, when the mobile terminal completes the n-th RSRP measurement of the adjacent base stations, obtain the n-1 RSRP measurement values of the mobile terminal for all the adjacent base stations, where n=2,3,4 ,…….

Step B2, acquiring the nth RSRP measurement values of all neighboring base stations by the mobile terminal.

Step B3, according to the n-1th measurement value, the n-th measurement value and the RSRP measurement interval Δt, calculate and obtain the RSRP gradient values Gradient _n-1,n (n=2,3,4) of all neighboring base stations respectively ,...).

Among them, the calculation formula of Gradient _{n-1, n} is:

$\mathrm{<span\; class="notranslate">\; Grad</span>}{\mathrm{<span\; class="notranslate">\; ient</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; RS</span>}{\mathrm{<span\; class="notranslate">\; RP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; RSRP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2,3,4</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>$

Step B4. Determine the information table including the corresponding cell IDs of all neighboring base stations and their RSRP change gradient values Gradient _n-1,n (n=2,3,4,...) as the RSRP gradient table.

Wherein, the exemplary structure of the RSRP gradient table is shown in Table 3:

Table 3. RSRP gradient table

Step B5. Record the RSRP gradient values Gradient _{n-1, n} (n=2, 3, 4, . . . ) of all adjacent base stations into the RSRP gradient table.

Fig. 3 is a flow chart of the first embodiment of the method for obtaining the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient when the target cell prediction event is met according to the present invention. In the embodiment of the present invention, when the target cell prediction event is satisfied, the step of obtaining the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient (step A5) may further include:

Step C1, query the RSRP gradient table, and obtain the cell identification ID1 _{n-1, n} , ID2 _{n-1, n} (n=2,3,4, ...).

Specifically, the mobile terminal can query the RSRP gradient table to obtain the cell identifiers ID1 _n-1,n and ID2 _n-1,n (n=2,3 ,4,...). Among them, ID1 _n-1,n (n=2,3,4,...) is the cell ID of the cell corresponding to the base station with the maximum value in the RSRP gradient value calculated after the nth measurement, ID2 _n-1,n (n =2,3,4,...) is the cell identity of the cell corresponding to the base station with the second largest value in the RSRP gradient value calculated after the nth measurement,

Step C2, query all ID1 _n-1,n (n=2,3,4,...), filter out the cell ID ID1 with the most occurrences, and determine ID1 as the cell ID of the cell with the largest RSRP gradient.

Specifically, the mobile terminal can query all ID1 _{n-1, n} (n=2, 3, 4, ...), filter out the cell ID ID1 with the most occurrences, and determine ID1 as the cell ID of the cell with the largest RSRP gradient.

Step C3. Query all ID2 _n-1,n (n=2, 3, 4,...), filter out the cell ID ID2 with the most occurrences, and determine ID2 as the cell ID of the cell with the second largest RSRP gradient.

Specifically, the mobile terminal can query all ID2 _{n-1, n} (n=2, 3, 4, ...), filter out the cell ID ID2 with the most occurrences, and determine ID2 as the cell ID of the second largest RSRP gradient cell .

In the embodiment of the present invention, the mobile terminal uses a filtering method to filter multiple RSRP gradient values of all neighboring base stations to filter out the wrong RSRP gradient values caused by unstable wireless environment factors, and finally obtain a more accurate RSRP maximum gradient cell and RSRP sub-large gradient cell. Improve the probability that the predicted target cell is the same as the target cell, reduce unnecessary resource reservation operations, and improve spectrum utilization. At the same time, the success rate of RRC reconstruction after RLF is improved.

4 is a flow chart of a first embodiment of the method for determining the cell identities of the first predicted target cell and the second predicted target cell according to the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient provided by an embodiment of the present invention. In the embodiment of the present invention, the step of the mobile terminal determining the cell identities of the first predicted target cell and the second predicted target cell according to the cell identities of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient (step A6) may also include:

Step D1. Determine the cell identity of the cell with the largest RSRP gradient as the cell identity of the first predicted target cell.

Specifically, the mobile terminal may determine the cell identity of the cell with the largest RSRP gradient as the cell identity of the first predicted target cell.

Step D2, determining the cell identity of the cell with the second largest RSRP gradient as the cell identity of the second predicted target cell.

Fig. 5 is a flow chart of the first embodiment of the method for acquiring an early handover preparation trigger event EarlyPreparEvent according to the current moving speed of the mobile terminal provided by the present invention. In the embodiment of the present invention, the step of the mobile terminal acquiring an early handover preparation trigger event EarlyPreparEvent according to the current moving speed of the mobile terminal (step A8) may further include:

Step E1, obtaining the current moving speed of the mobile terminal.

Specifically, the mobile terminal may acquire the current moving speed of the mobile terminal.

Step E2, query the moving speed v-EarlyPreparEvent mapping table, and obtain the corresponding EarlyPreparEvent according to the moving speed of the mobile terminal.

Specifically, the mobile terminal may query the moving speed v-EarlyPreparEvent mapping table (see Table 1), and obtain the corresponding EarlyPreparEvent according to the moving speed of the mobile terminal.

In the embodiment of the present invention, before querying the moving speed v-EarlyPreparEvent mapping table and obtaining the corresponding EarlyPreparEvent according to the moving speed of the mobile terminal, the above embodiment of the RLF recovery enhancement method further includes:

Set the EarlyPreparEvent as an A3 event with a smaller offset value (TTT=0ms).

In the embodiment of the present invention, the mobile terminal acquires the early handover preparation trigger event Early PreparEvent that matches the current moving speed. Compared with a single early handover preparation trigger event, the early handover preparation trigger event obtained in the embodiment of the present invention is more accurate, and further Improve the success rate of switching.

Fig. 6 is a flow chart of the first embodiment of the method for obtaining the priority of prepared cells and generating the prepared cell list Prepared-cell_list provided by the present invention. In the embodiment of the present invention, the mobile terminal obtains the priority of the prepared cell, and the step of generating the prepared cell list Prepared-cell_list (step A11) may also include:

Step F1, querying the RSRP gradient table to obtain the latest RSRP gradient value of the prepared cell.

Specifically, the mobile terminal can query the RSRP gradient table (see Table 3) to obtain the latest RSRP gradient value of the prepared cell.

Step F2, determining the priority of the prepared cell with the largest latest RSRP gradient value as 1.

Specifically, the mobile terminal may determine the priority of the prepared cell with the largest latest RSRP gradient value as 1.

Step F3, determining the priority of the prepared cell with the second largest RSRP gradient value as 2.

Specifically, the mobile terminal may determine the priority of the prepared cell with the second largest RSRP gradient value as 2.

Step F4, generating and backing up a Prepared-cell_list list of prepared cells according to the cell identifiers and priorities of the prepared cells.

Specifically, the mobile terminal may generate and back up the Prepared-cell_list list of prepared cells according to the cell identifiers and priorities of the prepared cells.

In the embodiment of the present invention, the mobile terminal obtains the proximity to the moving path of the mobile terminal according to the RSRP gradient value of the base station of the prepared cell, so as to give high priority to the prepared cell with high proximity, and finally to the prepared cell according to the priority. Prepare the cell list Prepared-cell_list for sorting. This enables the mobile terminal to find a suitable cell suitable for RRC reconstruction as soon as possible when inquiring one by one in the prepared cell list after RLF. The system interruption time is shortened, and the communication service quality is improved.

Fig. 7 is a flow chart of the first embodiment of the method for acquiring a handover execution event ExeEvent according to the current moving speed of the mobile terminal provided by the present invention. In the embodiment of the present invention, the step of the mobile terminal obtaining the handover execution event ExeEvent according to the current moving speed of the mobile terminal (step A12) may further include:

Step G1, obtaining the current moving speed of the mobile terminal.

Specifically, the mobile terminal can obtain the current moving speed.

Step G2, query the moving speed v-ExeEvent mapping table, and obtain the corresponding ExeEvent according to the moving speed of the mobile terminal.

Specifically, the mobile terminal may query the moving speed v-ExeEvent mapping table (see Table 2), and obtain the corresponding ExeEvent according to the moving speed of the mobile terminal.

In the embodiment of the present invention, before querying the moving speed v-ExeEvent mapping table and obtaining the corresponding ExeEvent according to the moving speed of the mobile terminal, the above embodiment of the RLF recovery enhancement method further includes: the A3 event with a larger offset value ( TTT=0ms) is determined as the switching execution event ExeEvent;

In the embodiment of the present invention, the mobile terminal obtains the matching handover execution event ExeEvent according to the current moving speed, and takes the A3 event with a larger offset value as the ExeEvent. In order to facilitate the early termination of T310 based on the handover execution event, it can not only ensure that the target cell has prepared the UE context, but also ensure that the prepared cell is a suitable cell.

Fig. 8 is a flow chart of the second embodiment of the method for enhancing RLF restoration in the embodiment of the present invention. In the embodiment of the present invention, the method for the base station to perform RLF recovery enhancement includes:

Step H1. Receive an early handover preparation indication Early_HO_Prepar_IND, which carries cell identities of the first predicted target cell and the second predicted target cell.

Specifically, the base station may receive an early handover preparation indication Early_HO_Prepar_IND, where the early handover preparation indication carries cell identities of the first predicted target cell and the second predicted target cell.

Step H2, according to the cell identifiers of the first predicted target cell and the second predicted target cell, send an early handover preparation request signaling Early_HO_Prepar_Request to the first predicted target cell and the second predicted target cell, and obtain the first predicted target cell and the channel resources of the second predicted target cell.

Step H3: When receiving the early handover preparation acknowledgment signaling from the predicted target cell, determine the cell identifier carried in the early handover preparation acknowledgment signaling Early_HO_Prepar_ACK as the cell identifier of the prepared cell.

Specifically, when receiving the early handover preparation confirmation signaling from the predicted target cell, the base station may determine the cell identifier carried in the early handover preparation confirmation signaling Early_HO_Prepar_ACK as the cell identifier of the prepared cell.

Step H4, sending a handover command HO_CMD to the mobile terminal, the handover command carrying the cell identifier of the prepared cell.

Specifically, the base station may send a handover command HO_CMD to the mobile terminal, where the handover command carries the cell identifier of the prepared cell.

In the embodiment of the present invention, the base station applies for channel resources for both the first predicted target cell and the second predicted target cell. After the T310 timer is prematurely terminated based on the handover execution event ExeEvent, when the target cell is the same as the prepared first predicted target cell or the second predicted target cell, the mobile terminal can quickly switch to the prepared first predicted target cell Or the second predicted target cell reestablishes the RRC connection. The reconstruction success rate is improved, the system interruption time is shortened, and the communication service quality is improved.

To describe the embodiments of the present invention in more detail, specific application scenarios of the present invention are given below.

FIG. 9 is a schematic diagram of a moving path and cell deployment of a mobile terminal in this application scenario. Among them, M and M' are respectively the positions where the mobile terminal predicts the target cell in the trajectory 1 and trajectory 2 scenarios. The cells covering track 1 and track 2 include micro cell PCellA, micro cell PCellB and micro cell PCellC. PCellA is the current serving cell of the mobile terminal. In this application scenario, the mobile terminal may be a mobile device on a high-speed vehicle.

As shown in FIG. 9 , when the mobile terminal moves along trajectory 1, the target cell that the mobile terminal will enter may be PCell B or PCell C. According to the positional relationship between trajectory 1 and PeNBB and PeNBC, it can be concluded that the proximity of PeNBB to trajectory 1 is greater than that of PeNBC to trajectory 1. The proximity mentioned here refers to the distance from the PeNB to the moving track. The embodiment of the present invention proposes to use the RSRP gradient value of the neighboring PeNB measured by the mobile terminal to indicate the proximity between the neighboring PeNB and the movement track. When the RSRP gradient value of a neighboring PeNB is larger, it means that the PeNB is closer to the moving track of the mobile terminal. And when the RSRP gradient value of a neighboring PeNB is positive, it means that the PeNB is in front of the mobile terminal; otherwise, it means that the PeNB is in the rear of the mobile terminal. Therefore, in the embodiment of the present invention, PCellB is determined as the first prediction target cell, and PCellC is determined as the second prediction target cell. Meanwhile, in the list of prepared cells, the priority of PCellB is higher than that of PCellC.

Similarly, when the mobile terminal moves along the trajectory 2, the target cell to be entered by the mobile interruption may be PCellB or PCellC. According to the positional relationship between trajectory 2 and PeNBB and PeNBC, it can be concluded that the proximity of PeNBC is greater than that of PeNBB, the first predicted target cell is PCellC, and the second predicted target cell is PCellB. In the list of prepared cells, the priority of PCellC is higher than that of PCellB.

For the convenience of describing in detail how to use the RSRP gradient value of the neighboring PeNB measured by the mobile terminal to indicate the proximity of the neighboring PeNB to the movement trajectory. The RSRP gradient analysis of neighboring base stations is given below.

FIG. 10 is a schematic diagram of RSRP gradient analysis of neighboring base stations in this application scenario. Wherein, the mobile terminal performs n-1 RSRP measurement at point A, and performs n-th RSRP measurement when moving to point B. In the figure, PeNB#0 is the current serving base station of the mobile terminal, and the micro base station PeNB#1 and the micro base station PeNB#2 are respectively located in the right front and left front of the UE. The direction vectors with point A as the starting point #1 and #2 as the end point are respectively The moduli of the two vectors are L1 and L2 respectively. The direction vectors with point B as the starting point #1 and #2 as the end point are respectively The moduli of the two vectors are L1', L2' respectively. θ ₁ and θ ₂ are respectively and angle. As shown in the figure, the moving track of the mobile terminal is closer to PeNB#1, then there is

L1<L2

ΔL1>ΔL2

in,

ΔL1=L1-L1'

ΔL2=L2-L2'

The change gradient value from the n-1th RSRP measurement value to the nth RSRP measurement value can be expressed as:

$\mathrm{<span\; class="notranslate">\; Grad</span>}{\mathrm{<span\; class="notranslate">\; ient</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; RS</span>}{\mathrm{<span\; class="notranslate">\; RP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; RSRP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}$

Let Gradient _n-1, n_1, Gradient _n-1, n_2 correspond to the RSRP gradient values of the micro base station PeNB#1 and the micro base station PeNB#2 respectively, then

$\mathrm{<span\; class="notranslate">\; Gra</span>}{\mathrm{<span\; class="notranslate">\; dient</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; RSRP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; RSRP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}$

$\mathrm{<span\; class="notranslate">\; Gra</span>}{\mathrm{<span\; class="notranslate">\; dient</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; RSRP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; RSRP</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}$

Among them, RSRP _i _j represents the RSRP value of the micro base station PeNB#j obtained by the mobile terminal in the i-th measurement, and Δt represents the measurement time difference between the n-1th measurement and the nth measurement.

The reference signal received power RSRP (ReferenceSignalReceivePower) is obtained from the reference signal transmitted power RSTP (ReferenceSignalTransmissionPower) of the neighboring base station through the channel loss of the wireless environment. The channel loss in the wireless environment mainly includes fast fading, path loss, penetration loss, shadow fading, etc. The channel loss is nonlinearly proportional to the distance from the mobile terminal to the base station. Suppose the channel loss in the wireless channel environment is LS(R), and R is the distance from the mobile terminal to the base station. Then the RSRP gradient value of the micro base station PeNB#1 and the micro base station PeNB#2 can be expressed as,

$\mathrm{<span\; class="notranslate">\; Gradie</span>}{\mathrm{<span\; class="notranslate">\; nt</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; PSTP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; RSTP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}$

$\mathrm{<span\; class="notranslate">\; Gradie</span>}{\mathrm{<span\; class="notranslate">\; nt</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; PSTP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; RSTP</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; LS</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;t</span>}}$

Obviously, according to the above formula,

Gradient _n-1, n_1＞Gradient _n-1, n_2

Through the above analysis draw the following conclusions:

(1) When the neighboring base station is located in front of the mobile terminal, the RSRP gradient value of the base station is positive; conversely, when the neighboring base station is located behind the mobile terminal, the RSRP gradient value of the base station is negative;

(2) When the neighboring base station is located in front of the UE, the higher the proximity of the moving path between the neighboring base station and the mobile terminal, the larger the RSRP gradient value of the base station; on the contrary, the lower the proximity of the moving path between the neighboring base station and the mobile terminal , the smaller the RSRP gradient value of the base station is.

Therefore, the mobile terminal can use the measured RSRP gradient value of the neighboring base station to indicate the proximity of the moving path between the neighboring base station and the mobile terminal.

In order to describe the handover signaling flow of the entire RLF recovery enhancement method and system in more detail, please refer to FIG. 11 . Fig. 11 is a flowchart of handover signaling in the embodiment of the present invention.

In order to describe in more detail the optimization of RLF recovery interruption time by the RLF recovery enhancement method, please refer to FIG. 12 , which is a schematic diagram of delay analysis of RLF recovery when a radio link fails in an embodiment of the present invention. In the embodiment of the present invention, the delay of the T310 timer triggered based on the handover execution event is much shorter than the traditional 1000 ms, and the generation of the prepared cell list saves the last 100 ms delay. Therefore, the embodiment of the present invention greatly shortens the system interruption time caused by RLF recovery.

The embodiment of the present invention also provides a corresponding mobile terminal embodiment, refer to FIG. 13 , and FIG. 13 is a schematic diagram of the mobile terminal provided by the embodiment of the present invention.

In the embodiment of the present invention, the mobile terminal includes:

The RSRP storage unit 101 is configured to continuously acquire the measured values of the RSRPs of all neighboring base stations;

The RSRP gradient storage unit 102 is used to calculate the RSRP gradient value and store the RSRP gradient table;

The first acquiring unit 103 is configured to acquire cell identities of the largest RSRP gradient cell and the second largest RSRP gradient cell;

The first determining unit 104 is configured to determine cell identities of the first predicted target cell and the second predicted target cell;

The second acquiring unit 105 is configured to acquire the current moving speed of the mobile terminal;

The third acquiring unit 106 is configured to acquire an early handover preparation trigger event EarlyPreparEvent according to the current moving speed of the mobile terminal;

The Early_HO_Prepar_IND sending unit 107 is configured to send an early handover preparation indication, which carries the cell identities of the first predicted target cell and the second predicted target cell, so that the base station of the current serving cell can Perform handover preparation operations in advance with the cell identity of the second predicted target cell and the predicted target cell;

The Early_HO_CMD receiving unit 108 is configured to receive an early handover command Early_HO_CMD, wherein the early handover command carries a cell identifier of a prepared cell;

Prepared cell information storage unit 109, used to generate and back up the prepared cell list Prepared-cell_list;

A fourth acquiring unit 110, configured to acquire a handover execution event ExeEvent according to the current moving speed of the mobile terminal;

T310 premature termination triggering unit 111, configured to prematurely terminate the T310 timer based on ExeEvent and declare RLF when the handover execution event ExeEvent is satisfied;

The mobile terminal provided by the embodiment of the present invention can be used in the first embodiment of the above-mentioned corresponding RLF recovery enhancement method.

The embodiment of the present invention also provides a corresponding base station embodiment, refer to FIG. 14 , which is a schematic diagram of the base station provided by the embodiment of the present invention.

In the embodiment of the present invention, the base station includes:

The Early_HO_Prepar_IND receiving unit 201 is configured to receive an early handover preparation indication, wherein the initiation handover preparation indication carries cell identities of the first predicted target cell and the second predicted target cell;

An early handover preparation execution unit 202, configured to perform an early handover preparation operation with the first predicted target cell and the second predicted target cell according to the cell identity of the first predicted target cell and the cell identity of the second predicted target cell;

Early_HO_Prepar_Request sending unit 203, configured to send early handover preparation request signaling;

Early_HO_Prepar_ACK receiving unit 204, configured to receive early handover preparation request acknowledgment signaling;

The Early_HO_CMD sending unit 205 is configured to send an early handover instruction Early_HO_CMD, wherein the early handover instruction carries the cell identifier of the prepared cell;

The base station provided by the present invention can be used in the aforementioned second embodiment of the corresponding RLF recovery enhancement method.

It should be noted that the specific execution process of each unit in the above device is based on the same idea as the method embodiment of the present invention, and the specific content may refer to the description in the method embodiment of the present invention, and will not be repeated here.

Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above-mentioned embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage medium can include: Read-only memory, random access memory, magnetic disk or optical disk, etc.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (10)

1. A radio link failure recovery enhancing method based on optimal reconstruction target cell selection, characterized in that: comprising the following steps: 1) The current serving base station of the mobile terminal continuously obtains the measurement of the signal quality of the mobile terminal to the base station, and analyzes whether the mobile terminal needs to start performing handover measurements to adjacent base stations, and if necessary, perform step 2); if not, continue Execute 1) step; 2) The mobile terminal continuously acquires the measured values of the RSRPs of all adjacent base stations; 3) When the nth RSRP measurement to the adjacent base station is completed, obtain and record the RSRP gradient value Gradient _{n-1, n} (n=2,3 ,4,...); 4) According to the signal quality of the current serving base station of the mobile terminal, judge whether it is possible to start predicting the target cell, if yes, perform 5) step; if not, perform 2) step; 5) When the target cell prediction event is satisfied, obtain the cell identifiers of the cell with the largest RSRP gradient and the cell with the second largest RSRP gradient; 6) According to the cell identification of the largest RSRP gradient cell and the second largest RSRP gradient cell, determine the cell identification of the first predicted target cell and the second predicted target cell; 7) Acquiring the current moving speed of the mobile terminal; 8) According to the current moving speed of the mobile terminal, obtain an early handover preparation trigger event Early PreparEvent; 9) When the early handover preparation trigger event Early Prepar Event is satisfied, the mobile terminal sends an early handover preparation indication Early_HO_Prepar_IND to the base station of the current serving cell, and the early handover preparation indication carries the cell identifiers of the first predicted target cell and the second predicted target cell , so that the base station of the current serving cell performs handover preparation operations in advance according to the cell identifiers of the first predicted target cell and the second predicted target cell and the predicted target cell; 10) receiving the early handover command Early_HO_CMD, the early handover command carries the cell identifier of the prepared cell; 11) Obtain the priority of the prepared cell, generate and back up the prepared cell list Prepared-cell_list; 12) Acquiring a handover execution event Exe Event according to the current moving speed of the mobile terminal; 13) When the handover execution event Exe Event is satisfied, the T310 timer is prematurely terminated based on the Exe Event and RLF is declared; 14) When the cell identity of the target cell meeting the Exe Event is the same as the cell identity of the prepared cell in the Prepared-cell_list, select the target cell with the same identity in the Prepared-cell_list to perform RRC connection re-establishment; 15) When the cell identity of the target cell that satisfies the Exe Event is different from the cell identity of the prepared cell in the Prepared-cell_list, search for a suitable cell in the order of priority from high to low for the cells in the Prepared-cell_list to perform RRC connection re-establishment . 2. The radio link failure recovery enhancement method based on the selection of the best reconstruction target cell according to claim 1, wherein the mobile terminal continuously obtains the RSRP measurement values of all adjacent base stations, specifically comprising: The mobile terminal is located in a radio link failure RLF frequent area; the radio link failure RLF frequent area is provided by a macro cell macrocell and several micro cell picocells to provide wireless communication services; the current access base station of the mobile terminal is a macro cell coverage The next micro cell base station PeNB; the adjacent base station is the macro cell base station MeNB covering the serving micro cell, or the adjacent micro cell base station PeNB. 3. The radio link failure recovery enhancement method based on the best reconstruction target cell selection according to claim 1, characterized in that: in step 3), when completing the nth RSRP measurement of the adjacent base station, obtain and Record the RSRP gradient values of the n-1th to nth measurements of all adjacent base stations, including: When completing the nth RSRP measurement of the adjacent base stations, acquiring the n-1th RSRP measurement values of the mobile terminal for all the adjacent base stations; Obtaining the RSRP measurement values of the mobile terminal for the nth time of all the neighboring base stations; Calculate and obtain RSRP gradient values Gradient _n-1,n (n=2,3,4,... ); Determine the information table containing the corresponding cell IDs of all neighboring base stations and their RSRP change gradient values Gradient _{n-1, n} (n=2,3,4,...) as the RSRP gradient table; Record the RSRP gradient values Gradient _n-1,n (n=2,3,4,...) of all adjacent base stations into the RSRP gradient table. 4. The radio link failure recovery enhancement method based on the best reconstruction target cell selection according to claim 1, characterized in that: in step 5), when the target cell prediction event is satisfied, obtain the maximum RSRP gradient cell and The cell ID of the cell with the second largest RSRP gradient, including: Query the RSRP gradient table to obtain the cell identifiers ID1 _n-1,n and ID2 _n-1,n of the two largest gradient values in the RSRP gradient values recorded each time; Query all ID1 _n-1,n , filter out the cell ID ID1 with the most occurrences, and determine ID1 as the cell ID of the largest RSRP gradient cell; Query all ID2 _n-1,n , filter out the cell ID ID2 that occurs most frequently, and determine ID2 as the cell ID of the cell with the second largest RSRP gradient. 5. the radio link failure recovery enhancement method based on the best reconstruction target cell selection according to claim 1 is characterized in that: in step 6), according to the cell identification of the largest RSRP gradient cell and the next largest RSRP gradient cell, determine The cell identifiers of the first predicted target cell and the second predicted target cell specifically include: Determining the cell identity of the largest RSRP gradient cell as the cell identity of the first predicted target cell; Determine the cell identity of the cell with the second largest RSRP gradient as the cell identity of the second predicted target cell. 6. The radio link failure recovery enhancement method based on the selection of the best reconstruction target cell according to claim 1, characterized in that: according to the current moving speed of the mobile terminal, the early handover preparation trigger event EarlyPrepar Event is acquired, specifically including : Acquiring the current moving speed of the mobile terminal; Query the moving speed v-Early Prepar Event mapping table, and obtain the corresponding Early Prepar Event according to the moving speed of the mobile terminal; The Early Prepar Event is set as the A3 event with a smaller offset value. 7. The radio link failure recovery enhancement method based on the selection of the best reconstruction target cell according to claim 1, characterized in that: in step 11), the priority of the prepared cell is obtained, and the prepared cell list Prepared is generated and backed up -cell_list, including: Querying the RSRP gradient table to obtain the latest RSRP gradient value of the prepared cell; Determine the priority of the prepared cell with the largest latest RSRP gradient value as 1; Determine the priority of the prepared cell with the second largest RSRP gradient value as 2; Generate and back up a Prepared- _{cell_list} list of prepared cells according to the cell identifiers and priorities of the prepared cells. 8. The radio link failure recovery enhancement method based on the selection of the best reconstruction target cell according to claim 1, characterized in that: according to the current moving speed of the mobile terminal, acquiring the handover execution event Exe Event specifically includes: Acquiring the current moving speed of the mobile terminal; Query the moving speed v-Exe Event mapping table, and obtain the corresponding ExeEvent according to the moving speed of the mobile terminal; The A3 event with a larger offset value is determined as the switching execution event Exe Event. 9. The radio link failure recovery enhancement method based on the selection of the best reconstruction target cell according to claim 1, characterized in that: according to the cell identifiers of the first predicted target cell and the second predicted target cell, the The first predicted target cell and the second predicted target cell send the early handover preparation request signaling Early_HO_Prepar_Request to obtain the channel resources of the first predicted target cell and the second predicted target cell; after receiving the early handover preparation confirmation signaling from the predicted target cell , determining the cell identity carried in the early handover preparation acknowledgment signaling Early_HO_Prepar_ACK as the cell identity of the prepared cell; sending a handover instruction HO_CMD to the mobile terminal, the handover instruction carrying the cell identity of the prepared cell. 10. A wireless link failure recovery enhancement system based on the selection of the best reconstruction target cell, characterized in that: it includes a mobile terminal and a base station; Mobile terminals include: The RSRP storage unit is used to continuously obtain the measured values of the RSRPs of all adjacent base stations; The RSRP gradient storage unit is used to calculate the RSRP gradient value and store the RSRP gradient table; The first obtaining unit is used to obtain the cell identifiers of the largest RSRP gradient cell and the next largest RSRP gradient cell; A first determining unit, configured to determine cell identities of the first predicted target cell and the second predicted target cell; a second acquiring unit, configured to acquire the current moving speed of the mobile terminal; A third acquiring unit, configured to acquire an Early Prepar Event that triggers an early handover preparation trigger event according to the current moving speed of the mobile terminal; The Early_HO_Prepar_IND sending unit is configured to send an early handover preparation indication, where the early handover preparation indication carries the cell identities of the first predicted target cell and the second predicted target cell, so that the base station of the current serving cell can use the first predicted target cell and the The cell identity of the second predicted target cell and the predicted target cell perform handover preparation operations in advance; The Early_HO_CMD receiving unit is configured to receive an early handover command Early_HO_CMD, wherein the early handover command carries the cell identifier of the prepared cell; The prepared cell information storage unit is used to generate and back up the prepared cell list Prepared-cell_list; The fourth acquisition unit is used to acquire the handover execution event ExeEvent according to the current moving speed of the mobile terminal; the T310 early termination trigger unit is used to terminate the T310 timer early based on the Exe Event when the handover execution event Exe Event is satisfied and declare RLF; Base stations include: The Early_HO_Prepar_IND receiving unit is configured to receive an early handover preparation indication, where the early handover preparation indication carries cell identities of the first predicted target cell and the second predicted target cell; An early handover preparation execution unit, configured to perform an early handover preparation operation with the first predicted target cell and the second predicted target cell according to the cell identity of the first predicted target cell and the cell identity of the second predicted target cell; Early_HO_Prepar_Request sending unit, used to send early handover preparation request signaling; The Early_HO_Prepar_ACK receiving unit is used to receive an early handover preparation request acknowledgment signaling; The Early_HO_CMD sending unit is configured to send an early handover command Early_HO_CMD, where the early handover command carries cell identifiers of prepared cells.