CN104093176B - A kind of method for avoiding producing pingpang handoff in LTE load balancing is migrated - Google Patents

Abstract

A kind of method for avoiding producing pingpang handoff in LTE load balancing is migrated, including cell in LTE network are periodically detected serving cell s load levels, judge whether cell s overloads；If cell s overloads, the configuration of some UE sending measurings is chosen, configuration UE persistently reports RSRP and RSRQ；Cell s obtains the load information that measurement reports each adjacent area, by the load of each adjacent area with receiving thresholding to be compared, obtains the adjacent area loaded less than thresholding is received, alternately purpose cell；Inquire about the UE of reporting measurement reports historical information, judge whether cell s once occurred pingpang handoff with one of alternative cell, neighboring area signal intensity during by comparing this and history pingpang handoff, judges whether to be adapted to initiate handover request to Target cell, so as to avoid producing pingpang handoff.The present invention ensures during LTE system load balancing, it is to avoid user is moved into adjacent base station and triggers pingpang handoff.

Description

A kind of method for avoiding producing pingpang handoff in LTE load balancing is migrated

Technical field

The invention belongs to moving communicating field, and in particular to one kind avoids producing during load balancing migration UE in the lte networks The method of raw pingpang handoff.

Background technology

In the protocol stack of 3GPP LTE access net systems, mobility load balance (Mobility Load Balancing, MLB) by being configured to part UE sending measurings, the measurement report that UE is reported is obtained, in advance cuts the certain customers of overloaded cells Low-load adjacent cell is changed to, for solving the unbalanced portfolio in multiple minizones, wireless resource utility efficiency is improved.

Pingpang handoff refers to back and forth repeatedly be switched between cell of the user equipment (UE) in system, and often UE is shorter in goal systems residence time after secondary switching, and this pingpang handoff is either to network still to user equipment All bring adverse effect.One side user equipment has carried out meaningless switching, causes QoS of customer to reduce.Another aspect base Need frequently to send and receive signaling message between standing, carry out flow burden to Netowrk tape, seriously waste wireless access system Resource.

Base station typically judges whether to meet the switch decision condition based on covering using A3 events, if that is, UE measures neighbour Area's signal is better than one difference of signal of serving cell, and UE is just switched to the more preferable adjacent area of signal by system.A3 events enter bar The formula of part：Mn+Ofn+Ocn-Hys ＞ Ms+Ofs+Ocs+Off, each related symbol is in standard agreement《3GPP TS 36.331》 5.5.4measurement report triggering chapters and sections in have a detailed description, reference can be made to corresponding document.

Base station typically judges whether to meet the switch decision condition based on load balancing using A4 or A5 events.When adopting During with A4 events：When neighboring area signal is better than threshold value Thresh, UE is just switched to the adjacent area by system, to equally loaded.A4 things The formula of part entry condition：Mn+Ofn+Ocn-Hys ＞ Thresh；When using A5 events：When service area signal compares threshold value Thresh1 is worse and neighboring area signal is more preferable than threshold value Thresh2, and UE is just switched to the adjacent area by system, to equally loaded.A5 The formula of event entry condition：Ms+Hys ＜ Thresh1 and Mn+Ofn+Ocn-Hys ＞ Thresh2.

MLB triggers the generation of pingpang handoff to have two kinds of reasons, a kind of not account for the switching based on load balancing Judgment condition and switch decision condition based on covering can produce conflict, and such as UE is due to triggering A4 or A5 event initiators In the switching of load balancing, cell d is switched to from cell s, now UE triggers A3 events immediately again, is switched to from cell d small Area s.Another is caused by the peculair motion feature of user, for example, user moves back and forth between two cells, to cause user Equipment constantly switches between two cells.

In existing LTE system standard criterion, in switching set-up procedure, source base station passes through handover request The historical information (UE history information) of the UE, is sent to target base by (HANDOVER REQUEST) message Stand, so that each base station can obtain the information of the cell accessed before this UE, the UE is judged by these information Whether pingpang handoff there occurs.

UE historical information (UE history information) is a chained list, chained list by UE " passing access Descending is rearranged cell information (Last Visited Cell Information) " sequentially in time, i.e., the nearest time The presence information of generation is stored in first chained list node, and the cell information of each passing access includes following content：

Cell categories (classification includes E-UTRAN/UTRAN/GERAN)；

The overall identification (Cell Global Identifier, CGI) of cell；

Cell type, its type can be " very small ", " small ", " medium " or " big "；

The time that UE is resident in cell.

In summary, from above-mentioned prior art introduction it can be found that table tennis can not be avoided according to existing UE historical informations Switching, because this method has only judged that UE is toggled between two cells, and UE is stopped in each wireless system Time, the concrete signal intensity or quality of UE each adjacent base station cell in each switching are not accounted for, therefore can not adopted Take effective measures, go adjust the switch decision condition based on load balancing come avoid and based on covering switch decision condition production Raw conflict.

The content of the invention

The problem to be solved in the present invention is how to avoid during MLB, and it is adjacent small to be that UE is switched to by equalizing traffic Pingpang handoff is triggered in area, so as to cause QoS of customer reduction and seriously waste asking for the resource of wireless access system Topic.

The technical scheme is that a kind of method for avoiding producing pingpang handoff in LTE load balancing is migrated, including Following steps,

Step one, the base station in LTE network is periodically detected the load level of each cell, if base station S detections is current Cell is cell s, judges whether cell s overloads, and is then to enter step 2, otherwise terminates flow；

Step 2, base station S chooses some UE in cell s and issues A4 or A5 measurement configurations, and the UE of configuration persistently reports survey Amount report, measurement report includes RSRP and RSRQ, and the RSRP is Reference Signal Received Power, and the RSRQ is reference signal The quality of reception；

Step 3, when base station S receives the measurement report that any UE is reported, base station S from the measurement report that UE is reported, Obtain the RSRP and RSRQ of each adjacent area reported；

Step 4, base station S obtains the load information of cell s all adjacent areas by X2 interface, on UE in step 3 Report each adjacent area for being related to carry out respective load respectively with receiving thresholding to be compared, and adjacent area less than receiving thresholding will be loaded as standby Purpose cell is selected, judges whether alternative purpose number of cells n is 0, if then terminating flow, if not into step 5；

Step 5, base station S inquires about the UE historical informations of reporting measurement reports, certain note for more whether having UE historical informations The UE persistent districts of record are alternatively one of purpose cell, and the switching that switch reasons cause for covering in step 4, And residence time is very short；If it is set this article and be recorded as the m articles, if the alternative purpose cell is cell d, into step Six, if not into step 8；

Step 6, base station S continues to search UE historical informations backward, and the UE for comparing the m+1 articles record of UE historical informations is stayed Whether be home cell, be if it is judged as pingpang handoff if staying cell, into step 7, if not into step 8；

Whether step 7, the gained cell d of base station S comparison steps two RSRP and RSRQ are respectively greater than the of UE historical informations M+1 bars institute recording cell d RSRP and RSRQ, if into step 8, if otherwise terminating flow；

Step 8, base station S fills in Last Visited in the UE history IE of X2HANDOVER REQUEST message UTRAN Cell Information, including addition cell destination cell RSRP and destination cell RSRQ is sent to cell d corresponding base station with the gained cell d of recording step two RSRP and RSRQ.

Moreover, in step one, judge whether cell overloads by judging whether cell load value is more than threshold value.

Moreover, in step 2, the UE for reporting A2 measurement reports is denoted as edge UE, it is preferential to choose edge UE sending measurings Configuration.

The present invention proposes UE switch determining methods in a kind of simple LTE network, base station is obtained the volume of UE switchings External information, so as to avoid the pingpang handoff triggered by load balancing to a certain extent.Pass through the contemplated above skill of the present invention Art scheme, compared with prior art, the present invention have following beneficial effect：

1st, parameter is simple and obtains convenient, and step 7 more used history RSRP and RSRQ, are added in step 8 Plus, this parameter is transmitted mutually by the X2 interface in LTE network, thus cell obtain its adjacent area handoff parameter it is more square Just.

2nd, without according to switching statistical result adjustment handoff parameter, arithmetic accuracy height adjustment speed is fast, focuses on considering user Perceive, by using Step 6: Step 7: step 8 can accurately control each UE to the variable structure contorl of Target cell, keeping away Exempt from pingpang handoff occur during MLB, so as to lift user's perception.

3rd, algorithm complex is low, without considering to conflict caused by serving cell is different with nearby region measurement configuration, due to step Eight can update destination cell RSRP, destination cell RSRQ during each switching, pass through step 7 Contrast judgement, the pingpang handoff for conflicting and causing caused by serving cell may finally be avoided different with nearby region measurement configuration.

Brief description of the drawings

Fig. 1 is the basic flow sheet of the embodiment of the present invention.

Embodiment

The present invention implements the detection process mechanism there is provided a kind of pingpang handoff, to avoid rattling as caused by load balancing Switching, so as to improve Consumer's Experience and network performance.Further detailed is made to the present invention below by embodiment combination Fig. 1 Describe in detail bright.

Referring to Fig. 1, the flow of embodiment is as follows：

Step one, the base station in LTE network is periodically detected the load level of each cell, and general base station can travel through all Respective cell is detected, if the current area of base station S detections is cell s, judges whether cell s overloads, if the cell-overload, Into step 2, otherwise terminate flow.

When it is implemented, can judge whether cell overloads by judging whether cell load value is more than threshold value, it is proposed that To the default value of threshold value in the cell all Physical Resource Block (Physical Resource Block, abbreviation PRB) all by Between 75% to 85% of total load during occupancy, the load detecting cycle can be by those skilled in the art's sets itself, general model Enclose for 1s to 10s.

Step 2, base station S selects some UE in cell s according to UE contexts, and sending measuring is configured to these UE, receives The UE of configuration continues reporting measurement reports, measurement report include RSRP (Reference Signal Received Power, Reference Signal Received Power) and RSRQ (Reference Signal Received Quality, Reference Signal Received Quality).

It is recommended that every time selection sending measuring configuration UE quantity for any active ues (active UE) quantity 5% to 10%.When it is implemented, the UE for reporting A2 measurement reports can be denoted as into edge UE, preferential edge UE sending measurings of choosing are matched somebody with somebody Put, it is remaining to randomly select.

Typically choose some UE and issue A4 or A5 measurement configurations, configuration UE persistently reports RSRP by measurement report (Reference Signal Received Power, Reference Signal Received Power) and RSRQ (Reference Signal Received Quality, Reference Signal Received Quality).Embodiment configuration UE measures configuration using A4, and configuration UE is persistently reported Measurement report, measurement report includes RSRP and RSRQ.Select the subsequent treatment of A5 measurement configurations similar, it is of the invention not superfluous State.

Step 3, when base station S receives the measurement report that any UE is reported, base station S from the measurement report that UE is reported, Obtain the RSRP and RSRQ for each adjacent area that the UE is reported.

In embodiment, UE reports A4 measurement reports, obtains the RSRP and RSRQ of each adjacent area reported.

Step 4, base station S obtains the load information of cell s all adjacent areas by X2 interface, on UE in step 3 Report each adjacent area for being related to carry out respective load respectively with receiving thresholding to be compared, and adjacent area less than receiving thresholding will be loaded as standby Purpose cell is selected, judges whether alternative purpose number of cells n is 0, wherein n is positive integer, if n is equal to 0, then it represents that the overload is small Area s, which is not found, can carry out the adjacent area of load balancing, terminate flow, if n does not enter step 5 for 0.

When it is implemented, base station described in general cell s can be by X2 interface specified in LTE protocol from consular district own base station Obtain the load information of each adjacent area, it is proposed that total negative when all PRB are occupied in the cell to the receiving default value of thresholding Between 50% to 60% carried.

Step 5, base station S inquires about the UE historical informations (UE history Information IE) of reporting measurement reports, Compare certain of UE historical informations record (being set to the m articles) UE persistent districts whether be in step 4 alternative purpose cell its One of (it is to be designated as cell d), and the switching that switch reasons cause for covering, and residence time is very short, less than setting Thresholding T.If into step 6, if not into step 8.UE history Information IE can switch from UE to be believed Extracted in order, be saved in the base station information that the UE of base station was once resident.

I.e. three below condition it is any be unsatisfactory for all enter step 8, all meet enters step 6：

Have in 1.UE historical informations alternative purpose cell in the UE persistent districts matching step four of a record wherein it One.

2. switch reasons are that covering is caused.

3 residence times are less than setting thresholding.

When it is implemented, time gate limit value T can be preset by those skilled in the art, general range is 2s to 10s.

There is provided in step 5 and judge whether UE once occurred table tennis and cut in current serving cell and alternative purpose minizone The most important condition changed.Current serving cell is cell s, alternatively referred to as home cell.

Step 6, base station S continues the UE historical informations that finding step five is mentioned backward, compares UE history Whether the UE persistent districts of Information IE the m+1 articles record are that (i.e. cell s), if it is judges for home cell For pingpang handoff, into step 7, if not into step 8.

There is provided in the step 6 and judge whether UE once occurred pingpang handoff in serving cell and alternative purpose minizone Second condition.

Step 7, (whether this RSRP and RSRQ of cell d) is both greater than step 6 institute to the more alternative purpose cells of base station S Stating the adjacent area in the m+1 articles record of UE historical informations, (cell d) RSRP and RSRQ if it is allows switching, into step Rapid eight, if otherwise terminating flow.

Referring to step 8, during present invention setting addition new record, the RSRP and RSRQ of adjacent area are recorded, therefore in the m articles note When the UE persistent districts of record are cell d, also there is cell d (history) RSRP and RSRQ in the m+1 articles record.

Through Step 5: six judge whether cell s once occurred pingpang handoff, the step with one of alternative purpose cell In rapid seven, the RSRP and RSRQ of the adjacent area are measured in this step 2 will be respectively greater than the RSRP for producing and being recorded during pingpang handoff And RSRQ, it could allow to again switch to corresponding adjacent area.

So by comparing the neighboring area signal intensity this time and during history pingpang handoff, it can be determined that if appropriate for target Cell initiates handover request, so as to avoid producing pingpang handoff.

Step 8, base station S is in the UE history Information IE of X2 HANDOVER REQUEST message Addition cell in Last Visited UTRAN Cell Information (referring to the agreement 9.2.1.43 chapters of TS 36.413) Destination cell RSRP, destination cell RSRQ, the neighboring area signal measured to the UE of recording step two is strong Spend (cell d Reference Signal Received Power, Reference Signal Received Quality).Enter step 8 formation UE history every time A new record in Information IE.

HANDOVER REQUEST message is handover request message.X2 HANDOVER REQUEST message is connect by X2 Mouthful send handover request message, specifically can X2 HANDOVER REQUEST message UE history Information Last Visited UTRAN Cell Information are filled in IE, Global Cell ID, Cell Type are filled in respectively, The cells such as Time UE stayed in Cell, and destination cell RSRP, destination cell RSRQ And the purpose base station that alternative purpose cell d is hung is sent to by base station S, then terminates flow.Standard agreement《3GPP TS 36.413》9.2.1.42 each cell that UE history Information IE are included is explained in detail in chapters and sections, the present invention It will not go into details.

It is special, to some UE of reporting measurement reports, may there are multiple alternative purpose cells all to meet Step 5: six, Seven condition, in principle UE can the good cell of prioritizing selection signal switch over.For the sake of improving efficiency, if multiple alternative During purpose cell (n be more than 1), UE first can do an arrangement according to signal quality, signal it is good put before, base station is from signal Good cell starts to travel through one by one, and traversal all proceeds by judgement from the condition of step 5 every time, find meet Step 5: six, The cell of seven conditionals just switches, and otherwise checks next cell according to signal sequence.Those skilled in the art can voluntarily root The basic procedure provided according to situation Application Example, modification adjustment on its basis, all should be within the scope of the present invention.

Run automatic continuously when it is implemented, flow of the present invention can be realized based on software engineering.

For the sake of ease of implementation, the utilization embodiment of the present invention presented below provides the example of method：

Cell 1 and cell 2 are belonging respectively to different base station, and adjacent area each other, have been switched on MLB functions.

Cell 1 using A3 events as covering switching judgment condition, when adjacent area RSRP be more than serving cell RSRP3dBm, UE will report A3 measurement reports.

Cell 2 using A3 events as covering switching judgment condition, when adjacent area RSRP be more than serving cell RSRP2dBm, UE will report A3 measurement reports.

UE1 accesses cell 1, has reported A2 measurement reports, edge customer is denoted as in UE contexts.

Now detect the load of cell 1 and exceed threshold value, and the load of cell 2 is less than receiving thresholding.Some UE are have chosen, Including UE1, issued A4 measurement configurations, configured according to the measurement that issues, if UE detect adjacent area RSRP be more than or equal to- 104dBm, will report A4 measurement reports.

UE1 has reported A4 measurement report serving cell RSRP:- 101dBm, serving cell RSRQ:- 8dB, adjacent area RSRP:- 104dBm, RSRQ:- 10dB, now UE historical information is sky, and without doing switch decision accordingly, directly UE1 is switched It is the no situation subsequently into step 8 to cell 2, i.e. step 5 result.

UE1 destination cell RSRP in cell 1 are have recorded in the UE historical informations of X2 handover requests:- 104dBm, destination cell RSRQ:- 10dB, residence time is 50s,

Assuming that UE1 is not moved, the signal received keeps constant, and now UE1 reports A3 to survey at once after cell 2 is switched to Amount report, the result measured is as the signal quality in the A4 measurement reports that cell 1 is reported, i.e. adjacent area RSRP is -101dBm, Adjacent area RSRQ:- 8dB, the RSRP of serving cell:- 104dBm, the RSRQ of serving cell:- 10dB, is now switched to cell by UE1 1。

In first insertion record UE1 destination cell in cell 2 of the UE historical informations of X2 handover requests RSRP:- 101dBm, destination cell RSRQ:- 8dB, residence time is 1s, and switch reasons are that covering is caused.

Exceed threshold value when cell 1 detects load again, and the load of cell 2 is less than receiving thresholding.It has chosen UE, including UE1, have issued A4 measurement configurations.

Assuming that UE1, which does not move the signal that receives, keeps constant, now report A4 measurement reports, the result measured with small Signal quality is the same in the A3 measurement reports that area 2 is reported, i.e. serving cell RSRP is -101dBm, serving cell RSRQ:-8dB, The RSRP of adjacent area:- 104dBm, the RSRQ of adjacent area:-10dB.UE historical informations are now traveled through, first record matching table tennis is found First condition of switching, that is, find UE and be once resident in alternative purpose cell, switch reasons cause for covering, and are resident Time is very short, less than setting thresholding 2s.It was found that second condition of Article 2 record matching pingpang handoff, i.e., in UE history messages Article 2 record on, find UE and be once resident in serving cell.Compare RSRP and RSRQ and UE history that now A4 is reported RSRP and RSRQ on the Article 2 record of message, it is found that signal intensity and quality all do not improve, therefore UE1 is not cut again Cell 2 is changed to, so as to avoid frequently pingpang handoff.

The present invention in existing x2 interface signalings using simple parameter is increased as can be seen here, by analyzing contrast history number According to the frequent pingpang handoff occurred during MLB can be avoided.

Above content is to combine specific embodiment further description made for the present invention, it is impossible to assert this hair Bright specific implementation is confined to these explanations.For general technical staff of the technical field of the invention, do not taking off On the premise of from present inventive concept, some simple deduction or replace can also be made, the protection of the present invention should be all considered as belonging to Scope.

Claims (2)

1. a kind of method for avoiding producing pingpang handoff in LTE load balancing is migrated, it is characterised in that：Comprise the following steps,

Step one, the base station in LTE network is periodically detected the load level of each cell, if the current area of base station S detections For cell s, judge whether cell s overloads, be then to enter step 2, otherwise terminate flow；

Step 2, base station S chooses some UE in cell s and issues A4 or A5 measurement configurations, and the UE of configuration continues reporting measurement report Accuse, measurement report includes RSRP and RSRQ, the RSRP is Reference Signal Received Power, and the RSRQ receives for reference signal Quality；

When being chosen, the UE for reporting A2 measurement reports is denoted as edge UE, it is preferential to choose the configuration of edge UE sending measurings；

Step 3, when base station S receives the measurement report that any UE is reported, base station S is obtained from the measurement report that UE is reported The RSRP and RSRQ of each adjacent area reported；

Step 4, base station S obtains the load information of cell s all adjacent areas by X2 interface, reports and relates to for UE in step 3 And each adjacent area carry out respective load respectively with receiving thresholding to be compared, and will load less than the adjacent area alternately mesh for receiving thresholding Cell, judge whether alternative purpose number of cells n is 0, if then terminating flow, if not into step 5；

Step 5, base station S inquires about the UE historical informations of reporting measurement reports, more whether there is certain record of UE historical informations UE persistent districts are alternatively one of purpose cell, and the switching that switch reasons cause for covering in step 4, and Residence time is very short；If it is set this article and be recorded as the m articles, if the alternative purpose cell is cell d, into step 6, Enter step 8 if not；

Step 6, base station S continues to search UE historical informations backward, compare the m+1 articles of UE historical informations record UE be resident it is small Whether area is home cell, is if it is judged as pingpang handoff, into step 7, if not into step 8；

Whether step 7, the gained cell d of base station S comparison steps two RSRP and RSRQ are respectively greater than the m+1 of UE historical informations Bar institute recording cell d RSRP and RSRQ, if into step 8, if otherwise terminating flow；

Step 8, base station S fills in Last Visited in the UE history IE of X2HANDOVER REQUEST message UTRAN Cell Information, including addition cell destination cell RSRP and destination cell RSRQ is sent to cell d corresponding base station with the gained cell d of recording step two RSRP and RSRQ.

2. the method for avoiding producing pingpang handoff in LTE load balancing is migrated as claimed in claim 1, it is characterised in that：Step In rapid one, judge whether cell overloads by judging whether cell load value is more than threshold value.