Embodiment describes in detail
Fig. 1 wherein implements several schematic diagrames in abutting connection with mesh and mobile radio station in the cellular radio telecommunication system of the present invention.Mesh is labeled as mesh A to mesh E, and two signal mobile radio stations that operate in the mesh are labeled as M1 and M2.
When the area of coverage in mobile radio station roaming out of net hole, the signal strength signal intensity that must measure adjoining cells is to determine that mobile radio station is reselect specific adjacent service mesh (" mesh is reselected " in the idle pulley) still should be handed over to one of adjoining cells (" handover " in the busy pattern).The location, checking (Presence Verification) and handover to occur be to deliver when keeping high signal quality everywhere when mobile radio station is mobile in cellular network to call out desired three processes between each mesh.The purpose of positioning function is that to search for specific mobile radio station be the mesh that the best radio receiving feature is arranged, the purpose that authentication function occurs is in the appearance of checking mobile radio station in selected mesh before the handover, and the purpose of hand-off functionality is according to positioning function and authentication function is sent to ongoing calling this calling of processing preferably safely from a mesh another mesh occurs.Also can in same mesh, be handed over to one other channel or such as between the grand mesh of rete cutaneum hole and covering with carry out handover from overlay mesh.
Mobile radio station in busy for being in (calling out) operator scheme has two kinds of selectable execution positioning functions and identification when should begin the method for handover, and a kind of method uses mobile radio station assisted hand-off (MAHO) and mobile radio station to carry out positioning function.
When mobile radio station begins to operate on the digital service channel, mobile radio station is measured the quality that radio link is connected by the error rate of measuring on the channel of its distribution with received signal intensity, and this mobile radio station is also measured the signal quality from the adjoining cells channel of tabulation in measuring sequence of base station.The channel that is listed in the measuring sequence (MAHO table) can upgrade and download to each mobile radio station as required.This MAHO table can customize for each mobile radio station according to predetermined criterion.Mobile radio station is periodically measured the received signal intensity of each channel of listing and the MAHO measurement is turned back to the base station in the MAHO table, the base station receives the channel quality message of its adjoining cells and compares these channels mutually.The signal strength signal intensity and the propagation path loss (transmission power level deducts the signal strength signal intensity of reception) of reception considered in the base station.Parameter in the base station determines whether hand-off request should send to mobile switching centre (MSC).
The another kind of localization method that is called classical localization method does not use MAHO, and by determining that radio link quality is carried out positioning function in serving BS and the adjacent base station thereof, serving BS is measured the quality that radio link connects by the received signal intensity of measuring on the service channel, and serving BS is then considered received signal intensity and propagation path loss (transmission power level deducts received signal intensity).Parameter in the base station is used for subsequently determining whether hand-off request should send to MSC, and MSC then asks to measure from the adjoining cells and the service channel of outer mesh, and wherein each mesh has the signal strength signal intensity receiver that is used for this purpose.The foundation that MSC arranges adjoining cells and outer mesh subsequently is used for the candidate list of handover.Mesh far away is not included in the candidate's mesh on the MAHO table usually.For example, for mesh A, mesh B can be the candidate's mesh on the MAHO table, and mesh C or mesh D then are not.
In the cellular system that does not utilize MAHO, the location is installed in each base station with demo plant, and the location can be measured by the signal strength signal intensity on each frequency of base station and adjoining cells operation thereof independently with demo plant.
The appearance of checking mobile radio station after localization process and in the mesh of carrying out the optimal candidate mesh of being appointed as handover with checking before the handover occurs, checking occurs according in the base station of adjoining cells, carrying out from the instruction of service MSC.In the time of on operating in the digital service channel, the old channel number of this mobile radio station, speed, time slot and digital verification colour code (DVCC) are provided for the base station in candidate's mesh of handover, and order this base station to verify the appearance of this mobile radio station on old channel.In candidate's handover mesh, utilize its position and demo plant to carry out the last signal strength measurement of this mobile station signal, and if this signal strength signal intensity cross predetermined threshold, then begin handover.In the time of on operating in analog voice channel, measure signal intensity on the voice channel that is used for service channel monitoring audible sound (SAT), this authorization information reports to MSC.
Can utilize MAHO checking carry out to occur or do not utilize MAHO to carry out positioning function, utilize location and demo plant in candidate's the base station of handover mesh confirmatory measurement to occur.
The location, checking and the top description of hand-off functionality occur and described handover in the overlay area of single MSC.Handover also can be crossed convertor boundary and carry out between mesh among the MSC and the outside mesh among another MSC.Except carrying out the location, occurring checking and the hand-off functionality, support the cellular network of the inter-exchange handover of mobile radio station must between included MSC, exchange outside mesh information.The standard agreement that is used for the inter-exchange signaling is IS-41, and this agreement is introduced in this as a reference.When between MSC, carrying out the inter-exchange handover, use known IS-41 message to come between switch, to transmit the desired information of handover of calling out.These message can comprise that handover measurement request (Hand MeasReq) message, facility orientation (Fac Dir) message, handover return (Hand Back) message and be handed off to third party (Hand Third) message.
The handover measurement request message is used for asking the location survey at the outside mesh of the localization method of classics, with the outside mesh of the optimal candidate that is identified for handover.This message also is used for asking the appearance authorization information of adjacent external mesh, with the checking mobile radio station in those mesh appearance and definite optimal candidate outside mesh.If service MSC determines to be handed off to an outer mesh among the adjacent MSC, then ask voice channel.
When since in the specific mesh voice channel congested and must abandon ongoing mobile radio station and call out maybe and must the refusal mobile radio station to call out when inserting, utilize method of the present invention that voice channel can be utilized.In fact, the present invention's " bump (bump) " utilizes another mobile radio station of voice channel, and utilizes the voice channel that discharges to provide service for the calling or the unaccepted access that will be dropped.Before giving an order with handover mechanism in existing location, be handed over to another mesh (that is the handover of acceleration) by the bump mobile radio station and be retained to by forcing by the service of bump mobile radio station with idle voice channel.
Referring to Fig. 1, M1 just roams into mesh B from mesh A again, but does not have idle voice channel in mesh B.Therefore, the inventive method is quickened (forcing) M2 and is handed over to mesh C or mesh D so that for M1 discharges voice channel the mesh B, the situation of calling out access is similar from mesh B.Insert cellular system if idle mobile radio station is arranged in mesh A and attempts at that, the present invention can quicken M2 from mesh B be handed over to mesh C or mesh D in case idle for this reason mobile radio station as orientation again call attempt be this system of access and discharge voice channel the mesh B.Selectively, the voice channel that discharges among the mesh B can be used for quickening the handover of mobile radio station among the mesh A, thereby discharges the voice channel of the mesh A can be used for serving new calling.
For Digital Cellular System, system has had candidate's mesh table, and each candidate's mesh has its MAHO signal measurement separately.For analogue system, picked up signal ionization meter from the adjoining cells of each mobile radio station periodically.In addition, enforcement of the present invention is identical.The present invention selects to have enough signal strength signal intensities that is used to serve (SS-SUFF) but is not enough to trigger candidate's mesh of handover (SS-HANDOFF), and the present invention also can select to have SS-HANDOFF but not trigger the mesh of handover owing to for example stop the control of handover alternately.In addition, the present invention can use the 3rd signal strength threshold value to represent to quicken the desired minimum signal strength of handover (SS-AHOFF), and this SS-AHOFF value is arranged between SS-SUFF and the SS-HANDOFF.When SS-AHOFF is set to equal SS-SUFF,, just allow the handover that quickens as long as there are enough signal strength signal intensities to be used for wanting maintained service.When SS-AHOFF is set to equal SS-HANDOFF, forbid the handover that quickens effectively.Therefore, system operator can utilize the SS-AHOFF thresholding to allow or forbid quickening handover, and the reduction amount that is allowed during the handover of control acceleration.
Can be by scanning mobile radio stations all in the congested mesh and selecting to have the signal strength signal intensity of the highest reception or a mobile radio station that MAHO measures is selected the mobile radio station that clashes into.For the mobile radio station calling that forces handover, speech quality has some to be reduced, but this reduction can be restricted to arbitrarily small quantity by adjusting the SS-AHOFF threshold value as mentioned above.
Say that from structure quickening to be handed off to idle voice channel (AHFVC) function is the part that voice channel is selected (VCS) function.Below table 1 be illustrated in call out start, the position of VCS in call terminations and the handover case.
Call phase | Message source | The message destination | Explanation |
MS starts | MS-system | System-MS | (voice channel selection) expression VC starts |
MS terminating | System MS-system | MS system-MS | Paging page response (voice channel selection) expression VC |
Handover | System MS-system | MS system-MS | Measured channel channel measurement (voice channel selection) handover |
Table 1: voice channel selection function in each call phase
The AHFVC function is the general module that uses during the VCS in all above-mentioned call phases.
The AHFVC function is applied in each mesh and is divided into two parts: continuously the background parts of carrying out and only in the time will carrying out the acceleration handover, just carry out require part.The major part of background parts is used to determine when with beginning mobile radio station handover in MAHO handles.As mentioned above, the signal strength signal intensity that receives the channel of moving station measuring from the MAHO table that offers them with measuring sequence, and the MAHO measurement returned to the base station.On the time of any appointment, in the mesh of appointment, measure to utilize by the MAHO that provides of mobile radio station of service and represent such as the table of following table 2.P11 to PMN represent by each mobile radio station for its separately the dBm that carries out of each adjoining cells in the MAHO table be the exemplary measurement of power levels of unit.
| NCELL
1 | ?NCELL
2 | … | ?NCELL
J | … | ?NCELL
N |
?MS
1 | ?P
11 | ?P
12 | | | | ?P1
N |
?MS
2 | ?P
21 | ?P
22 | | ?P2
J | | |
?MS
3 | ?P
31 | | | | | |
?… | | | | | | |
?MS
I | ?P
I1 | | | ?PI
J | | ?P
IN |
?… | | | | | | |
?MS
M | ?P
M1 | | | | | ?P
MN |
Table 2: the interior MAHO of mesh measures
A N adjoining cells of specifying mesh of M mobile radio station of table 2 expression service, a P
IJExpression is by I mobile radio station (MS
I) at J adjoining cells (NCELL
J) the last received signal intensity of measuring.If can't help the moving station measuring adjoining cells, then the corresponding power level of this adjoining cells is input as-∞ in this table.Utilize the MAHO of table 2 to measure, the background parts of AHFVC function can be discerned the mobile radio station with maximum received signal strength of each adjoining cells by the maximal term of determining every row, and is as shown below:
MAX-Level
J=MAX
I:1-M(PI
J)
Obtain adjoining cells (for example, NCELL
J) mobile radio station of the highest received signal intensity that reads is to quicken to be handed off to NCELL
JIdeal candidates person, such mobile radio station is expressed as: CAND-AH
J, acceleration is handed off to the candidate of mesh J.Therefore, if P
IJ=MAX-Level
J, CAND-AH then
J=MS1.
Given each adjoining cells NCELL
1To NCELL
NMAX-Level (maximum level), the background parts of AHFVC function forms the adjoining cells table of ordering, all adjoining cells satisfy and to be used to quicken the SS-AHOFF criterion of handover, and all adjoining cells sort to successively decrease in proper order according to the MAX-Level value of this mesh:
Sorted-Neighbor-List (the adjoining cells table of ordering)={ (Cell
A, Cell
B, Cell
C..., MAX-Level wherein
A〉=MAX-Level
B〉=MAX-level
C〉=
When needs quicken handover, carry out the part that requires of AHFVC function, the identification of the output of this part adjoining cells that to be mobile radio station be handed off to the mobile radio station that should force identification.The adjoining cells table of not considered inputs to and requires part.If Kong Xian mobile radio station was just being attempted connecting system in congested mesh in the past, the mesh table of eliminating can comprise the mesh that wherein directed examination has again been attempted and failed.For the mobile radio station that requires to be handed off to congested mesh, get rid of the mesh table and can comprise and wherein run into the congested mesh of voice channel.
The given Sorted-Neighbor-List that is derived by background parts and get rid of table requires part to calculate the difference table by deduct the eliminating table from Sorted-Neighbor-List, and this result is the classification chart of the adjoining cells that can attempt being handed off to:
In the situation of example, first quickens the NCELL in the whole adjoining cells table that the handoff candidate mesh can be a table 2
J, then force the desirable mobile radio station of handover to be: CAND-AH
J=MS
I
Therefore, at mesh Cell
JIn be that MSI attempts handover.If handover is successful, then freeing voice channel.If handover is unsuccessful, then next attempt second mesh in the AHFVC table, this handles continuation, until handover that success is arranged or the most AHFVC table of examination.
In the analogue system situation, as discussed above, mobile radio station does not provide channel measurement to system.On the contrary, each base station comprises that the signal strength signal intensity receiver is to monitor the signal level of the voice channel frequency of using in the adjoining cells.When the signal quality of mobile radio station in the service mesh drops to predetermined threshold when following, the signal level measuring of system's poll adjoining cells to provide each adjoining cells to receive on the voice channel of this mobile radio station of service.Have the adjoining cells of the signal strength signal intensity of high reception and represent the optimal candidate mesh of handover.If preferred mesh can not call accepted because voice channel is congested, then also can attempt being handed off to the adjoining cells of low received signal intensity.
In order to implement the present invention, a mesh must periodically obtain the received signal intensity level for each its adjoining cells of mobile radio station poll of its service.This poll is similar to the structure of MAHO table, but these channel measurements are up links and provide by system rather than by mobile radio station.Periodic signal strength values is used for compile list 2 subsequently.
Fig. 2 represents that wherein recurrence strengthens several schematic diagrames in abutting connection with mesh and mobile radio station in the enforcement cellular radio telecommunication system of the present invention.Recurrence refers to repeatedly use the ability of AHFVC function in needing each mesh of voice channel, generate the recurrent chain of handover.When mobile radio station M1 begins when mesh A roams to mesh B, require to be handed off to mesh B.If there is not available voice channel in mesh B, then AHFVC function identification is used to quicken the mobile radio station M2 of handover, and identification mesh C and mesh D are candidate's mesh of handover.If mesh C and mesh D are congested, then the AHFVC function recursively is applied to the candidate (that is first element of AHFVC table) of tool potentiality.In example shown in Figure 2, this candidate is mesh D, and the AHFVC function is discerned the mobile radio station M3 that is used to quicken handover subsequently, and identification mesh E is candidate's mesh of handover.If voice channel is available in mesh E, then attempts mobile radio station M3 and be handed off to mesh E.If success, it is available then making voice channel in mesh D, this voice channel is used for mobile radio station M2 subsequently and is handed off to mesh D from mesh B, and this handover discharges conversely and is used for mobile radio station M1 is handed off to mesh B from mesh A voice channel among the mesh B.
When recursively using the AHFVC function, adjoining cells must be geographically progressively away from the first service mesh, and the eliminating table of the mesh that this has considered in recurrent chain before utilizing and eliminating from the AHFVC table is realized.Thereby the eliminating table that sends the next stage recurrence to is one and offers the eliminating table union of the requirement part of AHFVC function with other AHFVC table of current level.
Fig. 3 A-3B is illustrated in to quicken the flow chart of steps carried out by the present invention during the handover procedure.If wherein implementing cellular telecommunication system of the present invention is digital system, as determined in step 30, this program moves on to step 31, collects MAHO and measure in step 31 interested mesh from the mobile radio station that service is provided for it.If this cellular system is not digital (that is, simulating), then in the received signal intensity (RSS) of step 32 service mesh for serviced its adjoining cells of mobile radio station poll of service mesh.Program moves on to step 33 subsequently, and the background parts of AHFVC function compiles the RSS value table of serviced mobile radio station and adjoining cells in step 33.In step 34, the AHFVC function derive to satisfy the Sorted-Neighbor-List of candidate's mesh of the ordering of the SS-AHOFF thresholding that is used to quicken handover.In step 35, from before when attempting handover, find by congested mesh and derive the eliminating table the mesh that inserts of the not acquisition system that tries again from its orientation, this eliminating table inputs to the part that requires of AHFVC function subsequently in step 36.Calling when requiring part, at first checking to determine whether Sort-Neighbor-List is sky (promptly not having the MAX-Level item to satisfy the SS-AHOFF thresholding) at step 36A.If like this, then the AHFVC function can not continue, and returns failure result.In step 37, the requirement of AHFVC function part derives the AHFVC table by deduct the eliminating table from Sorted-Neighbor-List.If the AHFVC table is empty (because Sorted-Neighbor-List is the subclass of eliminating table) in step 37A, then the AHFVC function can not continue, and returns failure result at step 37B.Otherwise this program then moves on to the step 38 of Fig. 3 B.
In step 38, program is provided with i=1.In step 39, then attempt being handed off to the Cell of AHFVC table
iIn step 41, determine whether handover is successful.If success, then program moves on to step 42, in step 42, returns the voice channel of release so that use.If unsuccessful at step 41 handover, then program moves on to step 43, determines whether to attempt being handed off to all mesh in the AHFVC table.If then program moves on to step 44, return failure.If also do not attempt being handed off to all mesh in the AHFVC table, then program moves on to step 45 and the next mesh that the i=i+1 program turns back to step 39 subsequently and attempts being handed off to the AHFVC table is set, this continuation that circulates is until freeing voice channel or unsuccessful all mesh of attempting being handed off to the AHFVC table.
Fig. 4 A-4B is illustrated in the flow chart of steps of being carried out by the present invention during the acceleration handover procedure of recurrence.If wherein implementing cellular telecommunication system of the present invention is digital system, as determined in step 40, this program moves on to step 41, collects MAHO in the serviced mobile radio station in step 41 from interested mesh and measures.If this cellular system is not digital (that is, simulating), then serve mesh in the received signal intensity (RSS) of step 42 for serviced its adjoining cells of mobile radio station poll of service mesh.Program moves on to step 43 subsequently, and in step 43, the background parts of AHFVC function compiles the RSS value table of serviced mobile radio station and adjoining cells.In step 44, the AHFVC function derive to satisfy the Sorted-Neighbor-List of the ordering candidate mesh of the SS-AHOFF signal strength threshold that is used to quicken handover.At step 44A, the recurrence control counter is set to zero and represents also not take place recurrence.In step 45, from before when attempting handover, find by congested mesh and derive the eliminating table the mesh that inserts of the not acquisition system that tries again from its orientation, this eliminating table inputs to the part that requires of AHFVC function subsequently in step 46.When calling this and require part, at first in step 46A, check to determine whether sorted-Neighbor-List is sky (that is, not having the MAX-Level item to satisfy the SS-AHOFF standard).If like this, the AHFVC function can not continue, and returns failure result.In step 47, the requirement of AHFVC function part derives the AHFVC table by deduct the eliminating table from Sorted-Neighbor-List.If the AHFVC table is empty (because Sorted-Neighbor-List is the subclass of eliminating table), then the AHFVC function can not continue, and returns failure result at step 47A.Otherwise program moves on to the step 48 of Fig. 4 B.
In step 48, program is provided with i=1.In step 49, then attempt being handed off to the Cell of AHFVC table
iIn step 51, determine whether handover is successful.If success, then program moves on to step 52, returns the voice channel of release so that use.If handover is unsuccessful in step 51, then program moves on to step 53, determines whether to attempt being handed off to all mesh in the AHFVC table.If do not attempt being handed off to all mesh in the AHFVC table, then program moves on to step 54 and i=i+1 is set, this program turns back to step 39 subsequently and attempts being handed off to the next mesh of AHFVC table, this continuation that circulates is until freeing voice channel or unsuccessful all mesh of attempting being handed off to the AHFVC table.
If attempted being handed off to all mesh in the AHFVC table in step 53, then program moves on to step 55, checks so that by determining whether that arriving recursive limit determines whether to attempt recurrence.If arrived recursive limit, then program moves on to program 56 and returns failure result.Note.If recursive limit is set to 0, then forbid recurrence, and the AHFVC function is returned failure result.On the recurrence of each grade, program determines whether to attempt the recurrence of another grade.If no show recursive limit in step 55, then allow recurrence to continue, and program moves on to step 57, program is provided with new eliminating table=(getting rid of table+AHFVC shows) in step 57, increase progressively recursion counter subsequently in step 58, this program turns back to step 46 and then at Cell
1Carry out the AHFVC function in (first element of AHFVC table).
Thereby, believe that from the foregoing description operation of the present invention and structure will be conspicuous.Though shown in be expressed as preferably with described method, apparatus and system, obviously can carry out various variations and modification and not break away from as defined spirit of the present invention and category in following claims.