CN1708166A - Blind hand off method from wideband code division multiple access system to worldwide mobile communication system - Google Patents

Abstract

The invention discloses a blind switching method from a wideband code division multiple access system (WCDMA) to a global system for mobile communication (GSM). The radio network controller pre-specifies the priority of the GSM neighbors of the WCDMA cell; generates a reference candidate set according to the WCDMA cells contained in the active set; takes the intersection of the GSM neighbors of all WCDMA cells in the reference candidate set, and uses the priority of the GSM cell in the intersection level, generating a target GSM cell retry candidate set for handover; returning the cells in the target GSM cell retry candidate set to the core network and user equipment in turn, so that the user equipment tries to switch to the cells in the target GSM cell retry candidate set. The priority attribute in the present invention improves the flexibility of the operator in the actual network application and the controllability of the algorithm; and makes full use of the existing GSM network resources to reduce the handover delay, thereby reducing the loss caused by untimely handover Talk about risk.

Description

Blind handover method from wideband code division multiple access system to global system for mobile communication

technical field

The invention relates to a handover technology between mobile communication systems, in particular to a blind handover method from a wideband code division multiple access system (WCDMA) to a global system for mobile communication (GSM).

Background technique

GSM is a time division multiple access communication technology, which is currently widely used in the second generation mobile communication (2G) network system, and has formed the largest mobile commercial network in the world.

WCDMA is a spread spectrum communication technology, which was mainly used in military communication in the early stage. Due to its high frequency utilization rate, strong anti-interference ability, large network capacity, good confidentiality performance, support for broadband multimedia, low power consumption of mobile phones and low transmission power, etc., it is currently used in the field of civil communications, especially in the It has gained wide attention and application in the three generation mobile communication (3G) network system.

In order to improve the utilization rate of spectrum resources and the capacity of the whole system, the radio frequency power of the base station in the existing cellular mobile communication system is limited within a certain cell range. When a mobile station leaves a cell and enters another cell, the signal received by the mobile station from the original cell must become weaker and weaker, while the signal it receives from the entering cell will become stronger and stronger. In order to maintain the communication quality of the mobile station, the connection of the mobile station must be switched from the original base station to the newly entered base station with stronger signal. This is the concept of handover in the cellular mobile communication system.

Since a GSM commercial network with complete coverage has been formed at present, starting from the comprehensive benefits of 3G network construction by operators, it will be required to use the existing network as much as possible to switch the services that can be supported by 2G networks in 3G network services to In the GSM network system.

From the way of realization, the handover from WCDMA to GSM can be divided into measurement-based handover and blind handover. The handover from WCDMA to GSM in the prior art is based on measurement.

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of a location of a cell where a user equipment (UE) is located. WCDMA-cell is a WCDMA system cell, GSM-cell is a GSM system cell, and UE is located in the intersection of WCDMA-cell 1, 2 and GSM-cell 1. When the UE moves to the position shown in Figure 1, the handover steps from WCDMA to GSM in the prior art are as follows:

1. The radio network controller (RNC) sends the handover target cell list; assuming that the optimal cell in the current active set is WCDMA-cell 1, the handover target cell is the GSM neighbor cell of WCDMA-cell 1: GSM-cell 1 , 2, 3, 6, 7;

The active set is the cell that provides services to the UE in the WCDMA system while the UE is communicating with the network. The number of cells in the active set can be one or more; the optimal cell is the pilot signal measured by the UE in the active set The cell with the best quality; in Figure 1, it is assumed that the cells in the active concentration are WCDMA-cell 1 and WCDMA-cell 2, and the optimal cell is WCDMA-cell 1;

2. The UE measures the signal quality of the target cell GSM-cell 1, 2, 3, 6, and 7;

3. The UE reports the measurement report of the target cell GSM-cell 1, 2, 3, 6, and 7;

4. According to the measurement report reported by the UE, the RNC selects the target cell for handover, such as GSM-cell 1 or GSM-cell 6, and tries to handover;

5. If the handover fails, return to wait for the UE's measurement report to trigger the next handover.

The handover from WCDMA to GSM in the prior art is based on measurement, and measurement takes time, including the time delay of signaling update and the time required for actual measurement. In some scenarios, such as when the core network (CN) requests to establish a new service, but the current cell cannot allocate the required resources, the measurement takes a long time, and the time for a signaling interaction cannot be very long The waiting time based on the measurement usually cannot meet the requirement of such a short time. The core network is an architectural concept in the WCDMA network, and it is one of the components of the WCDMA network, which has nothing to do with the radio access technology. For another example, if some users are expected to be handed over to the GSM cell due to the heavy load of the current cell, if the measurement-based handover method is used at this time, it will often lead to a greater system processing load and a loss of radio resources.

For the blind handover mode, the UE does not need to measure the signal quality of the target cell, and the RNC completely decides whether to perform the handover, and the RNC directly designates the UE to retry in the handover target GSM cell. Generally speaking, the RNC will decide whether to perform handover according to the location of the UE, and the handover speed is very fast.

However, the difficulty of blind handover is how to determine the handover target GSM cell, and how to make the handover target GSM cell adapt to changes in the actual application environment due to the movement of the UE. Because in an actual network, a WCDMA cell often has multiple GSM neighbor cells, and the moving direction of the UE is different, and the target GSM cell to be handed over is also different. In an actual network, it is difficult for the RNC to obtain information about the moving direction of the UE, and calls may be dropped during the handover, and the success rate of the handover is low. Because of this, under current conditions, blind handover is still difficult to be popularized and applied in actual networks.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a blind handover method from WCDMA to GSM, which reduces handover time delay and call drop risk caused by untimely handover.

In order to achieve the above object, the present invention provides a kind of blind handover method from WCDMA to GSM, RNC pre-designates the priority of the GSM adjacent area of WCDMA sub-district, and this handover process at least comprises the following steps:

A. Generate a reference candidate set according to the WCDMA cells included in the active set;

B, get the intersection of the GSM neighbors of all WCDMA sub-districts in the reference candidate set, according to the priority of the GSM sub-district in the intersection, generate the retry candidate set of the target GSM sub-district of handover;

C. Return the cells in the target GSM cell retry candidate set to the core network (CN) and the user equipment (UE) in sequence, so that the UE tries to perform handover to the cells in the target GSM cell retry candidate set.

In the above-mentioned scheme, the designated method of the priority of the GSM neighboring cell is: according to the probability of needing to switch to the GSM cell in practical application or the coverage of the GSM cell and the coverage of the WCDMA cell to designate, the greater the probability Or the higher the coincidence degree, the higher the priority of specifying the corresponding GSM cell.

In the above-mentioned scheme, described step A comprises:

A1. Select the optimal cell in the active set and put it into the reference candidate set;

A2. Select the non-optimal cells in the active set and put them into the reference candidate set;

A3. Determine whether the number of cells in the reference candidate set exceeds the pre-configured "reference candidate set size". If it exceeds, take the first "reference candidate set size" cells from the reference candidate set as the final reference candidate set. If not, then this The reference candidate set is the final reference candidate set.

In the above solution, before generating the reference candidate set, the RNC judges whether the measurement report of the cells in the inactive set is valid according to the reported reporting time of each recorded measurement report and the corresponding cell identity: if the measurement report is invalid, the active The WCDMA cells contained in the set are put into the reference candidate set; if the measurement report is valid, the measurement report of the inactive cells in the network cache is obtained, and the mapping value of the signal quality of the cell is calculated according to the measurement report, and then the WCDMA cells contained in the active set are The cell corresponding to the cell and the mapping value is put into the reference candidate set.

In the above scheme, the calculation of the mapping value of the cell signal quality includes the following steps:

C1. Obtain the current system time, and calculate the cache time of the measurement value of each cell in the measurement report;

C2. Discard the cells whose cache time is greater than the maximum valid time;

C3, substituting the cell measurement value, buffer time and linear factor into the formula "mapping value=cell measurement value-buffer time (s) * linear factor (dB/s)", calculates the mapping value of the current cell signal quality;

C4. Discarding cells whose mapping value is worse than the pre-configured "reference candidate set threshold";

C5. Sort the cells corresponding to the mapping values in descending order of the mapping values.

In the above scheme, the described putting the WCDMA cells contained in the active set and the cells corresponding to the mapping values into the reference candidate set is to first put the WCDMA cells contained in the active set into the reference candidate set, and then put the cells corresponding to the mapping values into the reference candidate set. The size order of the mapping values is put into the reference candidate set in turn.

In the above-mentioned scheme, described step B comprises:

B1, select the intersection of the GSM neighbors of all WCDMA cells in the reference candidate set;

B2, according to the priority of GSM sub-district, determine the selection order of GSM sub-district in the optimal sub-district of active set, according to the selection order of GSM sub-district in the optimal sub-district of active set, determine the selection order of GSM sub-district in the intersection;

B3, put the GSM cell in the intersection into the target GSM cell retry candidate set according to the selection order;

B4, judge whether the number of cells in the target GSM cell retry candidate set exceeds the pre-configured "GSM cell retry candidate set size", if it exceeds, then from the target GSM cell retry candidate set, get the previous "GSM cell retry candidate set size" " GSM cells are used as the final handover target GSM cell retry candidate set, if not exceeded, then this target GSM cell retry candidate set is the final handover target GSM cell retry candidate set.

The method further includes, before the handover, the RNC judges the service type currently requested by the CN: if the WCDMA cell where the UE is currently located cannot allocate sufficient resources for the service type currently requested by the CN, and the service type currently requested by the CN type, which can also be supported in the GSM network, then perform blind handover. Although the WCDMA cell where the UE is currently located can allocate sufficient resources for the service type currently requested by the CN, but it is desired to put the service type currently requested by the CN into the GSM network system; then perform blind handover.

The invention provides a blind switching method from WCDMA to GSM. When switching from WCDMA to GSM, there is no need for the UE to measure the GSM cells, which greatly reduces the delay in the switching process; the RNC generates a reference candidate set according to the WCDMA cells contained in the active set, and takes multiple WCDMA cells in the reference candidate set The intersection of two GSM neighboring cells generates a handover target GSM cell; thereby making full use of the existing information of the current network to reduce the handover delay and the risk of call drop caused by untimely handover.

Description of drawings

FIG. 1 is a schematic diagram of a location of a cell where a user equipment is located;

Fig. 2 is the flow chart of the blind handover method from WCDMA to GSM of a preferred embodiment of the present invention;

Fig. 3 is the flow chart of calculating cell signal quality mapping value in the preferred embodiment shown in Fig. 2;

Fig. 4 is a flow chart of generating a reference candidate set in the preferred embodiment shown in Fig. 2;

FIG. 5 is a flow chart of generating a handover target GSM cell retry candidate set in the preferred embodiment shown in FIG. 2 .

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples.

In the present invention, RNC pre-configures GSM adjacent cells for each cell in the WCDMA network, and specifies the priority of GSM adjacent cells. For the convenience of expression in this article, it is assumed that 0 represents the highest priority and 64 represents the lowest priority. Each GSM cell corresponds to a priority. The higher the priority, the greater the possibility of selecting it as the target cell during blind handover. The principle of specifying the priority of GSM adjacent cells is: in practical applications, the greater the probability of handover to GSM cells, or the higher the coverage of GSM cells and the coverage of WCDMA cells, the higher the priority of the corresponding GSM cells. higher.

For the schematic diagram shown in Figure 1, the GSM neighbor cells pre-configured by the RNC for WCDMA-cell 1 are GSM 6, 1, 3, 2, and 7, and GSM 6, 1, 3, and 2 are designated according to the above-mentioned principle of specifying priority The priorities of , 7 are 0, 1, 2, 3, 4 respectively; the GSM neighbor cells pre-configured by RNC for WCDMA-cell 2 are GSM-cell 1, 3, 4, 5, 6, and according to the above specified priority The principle specifies that the priorities of GSM-cells 1, 3, 4, 5, and 6 are 0, 1, 2, 3, and 4, respectively.

In the present invention, when handover is required, the RNC generates a reference candidate set according to the WCDMA cells included in the active set, takes the intersection of a plurality of GSM neighboring cells of the WCDMA cell in the reference candidate set, and generates a handover target GSM cell, according to the priority of the target GSM cell , the UE tries to perform handover in turn.

The network side caches the measurement reports reported by the UE, and records the reporting time and corresponding cell identity of each measurement report; the cached measurement report is the same-frequency measurement report that the UE performs timely measurement of the WCDMA cell according to the provisions of the protocol 25.331. In the way of overwriting and saving, the measurement report of the post-test covers the previous measurement report.

When the UE moves to the position shown in Figure 1, the RNC of the WCDMA network system judges the type of service currently requested by the CN: if the WCDMA cell where the UE is currently located cannot allocate enough space for the type of service currently requested by the CN Resources, and the service type currently requested by the CN can also be supported in the GSM network; or the WCDMA cell where the UE is currently located, although sufficient resources can be allocated for the service type currently requested by the CN, based on the maximum utilization For the purpose of existing GSM network resources, it is hoped to put the service type currently requested by the CN into the GSM network system, so blind handover can be performed.

Please refer to Fig. 2, Fig. 2 is the blind handover method flowchart from WCDMA to GSM of a preferred embodiment of the present invention, and this method at least includes the following steps:

Step 201: RNC generates a reference candidate set according to the WCDMA cells included in the active set;

Before generating the reference candidate set, the RNC judges whether the measurement report of the cells in the inactive set is valid according to the reported reporting time of each recorded measurement report and the corresponding cell identity: if the measurement report is invalid due to cache time WCDMA cells contained in the set, generate a reference candidate set; if the measurement report is valid, obtain the measurement report of the non-active set of cells cached by the network, and calculate the mapping value of the signal quality of the cell according to the measurement report, and then according to the WCDMA cells contained in the active set Generate a reference candidate set for the cell corresponding to the mapping value;

Step 202: Get the intersection of the GSM neighbors of all WCDMA cells in the reference candidate set, and generate a handover target GSM cell retry candidate set according to the priorities of the GSM cells in the intersection;

Step 203: return to the CN and UE in turn the cells in the target GSM cell retry candidate set, so that the UE tries to perform handover to the cells in the target GSM cell retry candidate set.

Before the reference candidate set is generated in step 201 in FIG. 2, if the measurement report buffered by the network side is valid, the process of calculating the mapping value of the cell signal quality is shown in FIG. 3, and FIG. 3 is the preferred embodiment shown in FIG. 2 A flow chart for calculating the cell signal quality mapping value, the flow chart further includes the following steps:

Step 301: Obtain the current system time, and calculate the cache time of each cell measurement value in the cached measurement report;

Step 302: Discarding cells whose cache time is greater than the maximum valid time, the maximum valid time is a configurable parameter and can be adjusted according to the actual application environment;

Step 303: substituting the cell measurement value, buffer time and linear factor into the formula "mapping value=cell measurement value-buffer time (s)×linear factor (dB/s)" to calculate the mapping value of the current cell signal quality;

Among them, the cell measurement value is the signal-to-noise ratio (E _c /N ₀ ) of the pilot channel (CPICH) stipulated in the protocol 25.331; the linear factor is used to estimate the decay rate of the signal strength measured by the UE over time, and the unit is dB/ s; The configuration of the linear factor mainly considers the signal fading characteristics of the environment where the cell is located and the moving speed of the UE. For example, if the UE moves at a speed of 100km/h, the moving distance in 2 seconds is about 55m, while in the macro cell model 50m The path loss is -1.92dB, which is the path loss difference between 400m and 450m in the macro cell model, so the linear factor can be approximated as 1dB/s; the macro cell model is a corrected path loss model;

Step 304: Discard the cells whose mapping value is worse than the pre-configured "reference candidate set threshold"; the "reference candidate set threshold" is a configurable parameter and can be adjusted according to the actual application environment;

Step 305: Sort the cells corresponding to the mapping values in descending order of the mapping values, wherein the first cell represents the cell with the best quality.

Step 201 in Fig. 2 generates the process of reference candidate set as shown in Fig. 4, and Fig. 4 is the flow chart of generating reference candidate set in the preferred embodiment shown in Fig. 2, and this flow chart further comprises the following steps:

Step 401: Select the optimal cell in the active set and put it into the reference candidate set;

In the present embodiment, for the schematic diagram shown in Figure 1, the optimal cell in the active set is WCDMA-cell1, so WCDMA-cell 1 is selected to be put into the reference candidate set;

Step 402: select the non-optimal cell in the active set and put it into the reference candidate set; in this embodiment, for the schematic diagram shown in Figure 1, select WCDMA-cell 2 and put it into the reference candidate set;

Steps 403-405: Determine whether the number of cells in the reference candidate set exceeds the pre-configured "reference candidate set size", if so, take the first "reference candidate set size" cells as the final reference candidate set, if not, then the reference candidate set The set is the final reference candidate set; "Reference candidate set size" is a configurable parameter, through which the range of generated candidate sets can be adjusted.

If the measurement report buffered by the network side is valid, after calculating the mapping value of the cell signal quality, the cell corresponding to the sorting mapping value should be selected before step 403, and the mapping value is sequentially compared with the mapping value according to the order of the mapping value from high to low. The corresponding cell is put into the reference candidate set;

Step 203 among Fig. 2 generates the process of the target GSM sub-district retry candidate set of switching as shown in Figure 5, and Fig. 5 is the flow chart of generating the target GSM sub-district retry candidate set of switching in the preferred embodiment shown in Figure 2, The flowchart further includes the following steps:

Step 501: Select the intersection of the GSM neighbors of all WCDMA cells in the reference candidate set;

In this embodiment, for the schematic diagram shown in Figure 1, there are two WCDMA sub-districts, WCDMA-cell 1 and WCDMA-cell 2, in the reference candidate set; the GSM neighbors of WCDMA-cell 1 are GSM-cell 1, 2, 3, 6, 7. The GSM neighbors of WCDMA-cell 2 are GSM-cell 1, 3, 4, 5, 6, then the intersection of the GSM neighbors of WCDMA-cell1 and WCDMA-cell 2 is GSM-cell 1, 3, 6;

Step 502: Determine the selection order of the GSM cells in the intersection according to the selection order of the GSM cells in the optimal cell in the active set;

According to the above, the intersection GSM-cell 1, 3, and 6 are selected according to the priority level in WCDMA-cell 1, and the selection order is GSM-cell 6, 1, 3, and in WCDMA-cell 2 according to the priority level , the selection order is GSM-cell 1, 3, 6; and the selection order of the GSM cells in the intersection set should be determined according to the selection order of the GSM cells in the active set optimal cell in the intersection set, and WCDMA-cell 1 is the best cell in the active set. Therefore, the selection order of GSM-cell 1, 3, and 6 in the intersection should be determined according to the selection order of GSM-cell 1, 3, and 6 in WCDMA-cell 1: that is, the selection of GSM-cell 1, 3, and 6 The sequence is GSM-cell 6, 1, 3;

Step 503: put the GSM sub-district in the intersection into the target GSM sub-district retry candidate set according to the selection order; in this embodiment, for the schematic diagram shown in Figure 1, put GSM-cell 6, 1, 3 into the target GSM sub-district to retry in turn candidate set;

Steps 504-506: Determine whether the number of cells in the target GSM cell retry candidate set exceeds the pre-configured "GSM cell retry candidate set size", and if so, take the first "GSM cell retry candidate set size" GSM cells as the final The target GSM cell retry candidate set for handover, if not exceeded, then the target GSM cell retry candidate set is the final handover target GSM cell retry candidate set; "GSM cell retry candidate set size" is a configurable parameter, through which Parameters can adjust the range of generated candidate sets;

In the present embodiment, for the schematic diagram shown in Figure 1, assuming that the number of the maximum handover target cell set is 3, then the set formed by the intersection GSM-cell 6, 1, 3 is the retry candidate set of the handover target GSM cell.

In this embodiment, for the schematic diagram shown in Figure 1, after generating the target GSM cell retry candidate set for handover, according to the selection order of GSM-cell 6, 1, and 3 in the target GSM cell retry candidate set, first select GSM-cell 6 As the handover target cell, return GSM-cell6 to CN and UE through signaling, so that UE can try to switch to GSM-cell 6; if the handover fails in GSM-cell 6, then return GSM-cell to CN and UE through signaling Cell 1 is the target cell for handover, so that the UE tries to handover to GSM-cell 1, and so on, until the handover succeeds or all fail.

The invention provides a blind switching method from WCDMA to GSM. When switching from WCDMA to GSM, there is no need for the UE to measure the GSM cells, which greatly reduces the delay in the switching process; the RNC generates a reference candidate set according to the WCDMA cells contained in the active set, and takes multiple WCDMA cells in the reference candidate set The intersection of two GSM neighboring cells generates the target GSM sub-district of handover; the priority attribute in the present invention improves the flexibility and the controllability of the operator's application in the actual network; the present invention makes full use of the existing GSM network resources and reduce handover delay, thereby reducing the risk of call drop caused by untimely handover.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1, a kind of blind switching method from broadband CDMA system WCDMA to global system for mobile communications GSM is characterized in that, radio network controller (RNC) is specified the priority of the GSM adjacent area of WCDMA sub-district in advance, and this handoff procedure may further comprise the steps at least:

A, according to the WCDMA sub-district that comprises in the active set, generate with reference to Candidate Set;

B, get the common factor with reference to the GSM adjacent area of all WCDMA sub-districts in the Candidate Set, the priority according to GSM sub-district in occuring simultaneously generates the target GSM sub-district retry Candidate Set that switches;

C, return sub-district in the retry Candidate Set of target GSM sub-district to core net CN and user equipment (UE) successively, make UE attempt switching to the sub-district in the retry Candidate Set of target GSM sub-district.

2, blind switching method according to claim 1, the designation method that it is characterized in that the priority of described GSM adjacent area is: the probability that switches to the GSM sub-district according to needs in actual applications or the coverage of GSM sub-district and the coverage registration of WCDMA sub-district are specified, probability is big more or registration is high more, then specifies the priority of corresponding GSM sub-district just high more.

3, blind switching method according to claim 1 is characterized in that described steps A comprises:

Optimum subdistrict in A1, the selection active set is put into reference to Candidate Set;

Non-optimum subdistrict in A2, the selection active set is put into reference to Candidate Set;

Whether A3, judgement surpass pre-configured " with reference to the Candidate Set size " with reference to number of cells in the Candidate Set, if surpass then from the reference Candidate Set, " with reference to the Candidate Set size " individual sub-district is as final reference Candidate Set before getting, and then this is exactly final reference Candidate Set with reference to Candidate Set if do not surpass.

4, blind switching method according to claim 1, it is characterized in that, before described generation is with reference to Candidate Set, RNC is according to calling time on each measurement report that writes down and the corresponding district sign, whether the measurement report of judging sub-district in the non-active set is effective: if measurement report is invalid, then, put into reference to Candidate Set directly with the WCDMA sub-district that comprises in the active set; If measurement report is effective, then obtain the measurement report of sub-district in the non-active set of network terminal buffer memory, and, with the WCDMA sub-district and the mapping value corresponding district that comprise in the active set, put into then with reference to Candidate Set according to the mapping value of measurement report calculation plot signal quality.

5, blind switching method according to claim 4 is characterized in that the mapping value of described calculation plot signal quality may further comprise the steps:

C1, obtain current system time, calculate the cache-time of each cell measurement value in the measurement report;

C2, abandon the sub-district of cache-time greater than maximum effective time;

C3, cell measurement value, cache-time and linear factor substitution formula " mapping value=cell measurement value-cache-time (s) * linear factor (dB/s) ", calculate the mapping value of current cell signal quality;

C4, abandon the sub-district that mapping value is worse than pre-configured " with reference to the Candidate Set thresholding ";

C5, by the descending rank order mapping value corresponding district of mapping value.

6, according to claim 4 or 5 described blind switching methods, it is characterized in that described the WCDMA sub-district and the mapping value corresponding district that comprise in the active set being put into reference to Candidate Set, be earlier the WCDMA sub-district that comprises in the active set to be put into reference to Candidate Set, and then the mapping value corresponding district is put into reference to Candidate Set successively by the size order of mapping value.

7, blind switching method according to claim 1 is characterized in that described step B comprises:

B1, select common factor with reference to the GSM adjacent area of all WCDMA sub-districts in the Candidate Set;

B2, according to the priority of GSM sub-district, determine the selecting sequence of GSM sub-district in the active set optimum subdistrict, according to the selecting sequence of GSM sub-district in the active set optimum subdistrict, the selecting sequence of GSM sub-district in determine occuring simultaneously;

B3, will occur simultaneously by selecting sequence in the GSM sub-district put into target GSM sub-district retry Candidate Set;

B4, judge that whether the number of cells in the retry Candidate Set of target GSM sub-district surpasses pre-configured " GSM sub-district retry Candidate Set size ", if surpass then from the retry Candidate Set of target GSM sub-district, " GSM sub-district retry Candidate Set size " individual GSM sub-district is as the final target GSM sub-district retry Candidate Set that switches before getting, and this target GSM sub-district retry Candidate Set is exactly the final target GSM sub-district retry Candidate Set that switches if do not have to surpass then.

8, blind switching method according to claim 1, it is characterized in that this method further comprises, the type of service that RNC sets up the CN current request before switching is adjudicated: UE present located WCDMA sub-district, if can not distribute enough resources for the type of service that the CN current request is set up, and the type of service that the CN current request is set up, in the GSM network, also can be supported, then carry out blind switching.

9, blind switching method according to claim 1, it is characterized in that this method further comprises, the type of service that RNC sets up the CN current request before switching is adjudicated: UE present located WCDMA sub-district, though can distribute enough resources for the type of service that the CN current request is set up, but wish the type of service that the CN current request is set up is put into the GSM network system, then carry out blind switching.

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