CN1119066C - Adaptive targeting level - Google Patents

Abstract

The present invention comprises an apparatus and method for providing paging messages for a mobile wireless device based on the rate of movement of the mobile wireless device. For relatively stationary mobile wireless devices, paging messages are to be sent within the cell in which the mobile wireless device is located, while increased mobility wireless devices receive their paging messages on a local area basis. Depending on the mobility of the mobile radio, entering a new cell, entering a new positioning area, expiration of a predetermined time limit, and the status of a new cell positioning flag, the mobile radio will always perform a positioning update if it is optimal to perform a positioning update. In order to optimize the burden of location area update and the burden of unnecessary paging broadcast, it is necessary to define a function for location update on a location area basis or on a cell basis according to the above-mentioned factors.

Description

Adaptive targeting level

field of invention

The present invention relates to telecommunications systems, and in particular to the delivery of paging messages for mobile radio systems.

Background and overview of the invention

Mobile radio telecommunication systems consist of cellular structures in which mobile radio devices can enter and leave geographically defined "cells". It is recognized that some mobile wireless devices may be more or less mobile than others in a cell structure. For example, some wireless devices may be used in applications that move more frequently, so that the device crosses a new cell boundary every few minutes. A simple mobile wireless device can move a lot for a period of time (such as during regular business hours), but after an hour, its mobility will decrease.

In a cell structure, the mobile radio network is designed to communicate with mobile radio devices using the broadcast system. Thus in the exemplary embodiment, a single base station may serve each cell defined within a geographic area, and a mobile wireless switching center may serve each base station within a predetermined area. In an exemplary embodiment, the base station may define the geographical area of the cell on the basis of the transmission distance and characteristics related to each base station in the cell. Similarly, the mobile wireless switching center can define a location area, which can be geographically defined based on the best traffic characteristics between the mobile wireless switching center and the base stations within the location area.

A mobile wireless switching center can provide the following two important functions for any particular mobile wireless device. First, it can preserve a more or less precise location of the mobile wireless device within the cellular structure so that the mobile wireless device can be found when an incoming call for the mobile wireless device is received. For a mobile wireless device, one location update method is to periodically notify the network of its location. According to the period of location update, this method can provide better location information for each mobile wireless device, but doing so will increase the burden on system resources due to multiple location update transmissions. Various schemes have been developed to balance and optimize the desire to obtain more positioning information and minimize the burden of positioning updates.

Another important process in the mobile wireless switching center is paging. Whenever an incoming call is received for a mobile wireless device, the mobile wireless switching center sends a paging message to the mobile wireless device. Such procedures are well recognized and understood in the art. Paging messages intended for a particular mobile wireless device are sent within a location area, which may be defined by a number of cells adjacent to the cell associated with the last known location of the mobile wireless device. In this context, a location area is defined as a group of cells (one or more) within which a mobile station can move freely without updating the network about its new location. In practice, the location area is the smallest area that the network is aware of where a particular mobile station is at the moment. Combining multiple cells into a location area for paging purposes is a known technique.

Another paging technique is described in US Patent (No. 5,289,527) where all cells have a published geographic location and mobile wireless device registrations are valid within a specified radius of the cell location. In that case, the mobile station needs to register as soon as it enters a new cell, ie outside the radius of the previous cell in which it was previously registered.

In systems where a location area is the smallest known location a mobile station is in (whether the location area is predetermined or determined dynamically), paging messages for a particular mobile station are sent on the paging channel to within the location area of all districts. Although paging messages are sent to all cells in the location area, many paging messages in the paging channel are wasted because the mobile station will only receive one of the many messages sent, that is, send The message to the cell where the mobile station is actually located. That is, although the network will send paging messages to multiple cells within the location area, since the mobile station can only be in one cell at a time, it can only receive one paging message from the network. All messages sent to cells where the mobile station is not present (for the purpose of paging the mobile station) place unnecessary load on the paging control channel.

Of course, if the load of the location registration operation is increased, the paging load will be reduced accordingly, which means that if the location of the mobile station learned by the system can be accurate to the cell level on the basis of adding location updates, then the paging load will be Eliminate paging load on unnecessary cells. In order to ensure that paging can be concentrated in the area in which the mobile station is located, the location of the mobile station must be updated relatively more often (eg whenever the mobile station enters a new cell). This means that a large positioning update burden will be imposed on the system. The issue of balancing the cost/burden of location updates and the cost/burden of paging is discussed in the article "Location Management Methods For Third-generation Mobile Systems" (IEEE Communications Magazine, August 1997 ) are described in detail. Therefore, a compromise needs to be made between the location update mode and the paging load, but the prior art shows that it is impossible to reduce the other load (location update or paging) without increasing one load.

However, if the mobility of the various wireless devices is considered, the paging system can be tailored to the specific characteristics of the mobile wireless device, ie the rate of movement of the mobile wireless device. Thus in accordance with one aspect of the present invention, a decision can be made based on the mobile behavior of the mobile station whether to issue paging messages for a mobile wireless device on a location area basis or a cell area basis. Various methods of determining the mobility of a mobile station are known, and the present invention is not limited to these particular methods. Depending on the mobility of any particular wireless device, location area level paging operations may be employed or cell level paging operations may be employed.

These and other objects and benefits of the present invention may be more fully understood and appreciated by examining the detailed description of preferred exemplary embodiments of the invention which follows, given with reference to the accompanying drawings, in which:

Brief description of the drawings

Figure 1 is an overview representation of a cellular structure;

FIG. 2 is a table for illustrating an exemplary embodiment of a positioning update process according to an exemplary embodiment of the present invention; and

3 and 4 present flow charts according to exemplary embodiments of the present invention.

Detailed description of the drawings

In the presented preferred embodiment of the invention, the mobility of the various mobile stations is considered in determining how to invoke paging messaging. Since the mobility of the mobile stations is not consistent and different, it is necessary to determine the mobility rate of each mobile station. The rate of movement of a mobile station can most easily be determined based on the frequency at which location updates are performed by the mobile station. Those mobile stations with higher moving speed usually perform location updating more frequently, and according to their lower location updating frequency, it can be judged that the moving speed of other mobile stations will also be relatively lower. That is, a network serving a mobile station that frequently performs location updates may assume that the mobile station is moving at a high speed. On the other hand, because some mobile stations are only moving within the same cell for a long period of time and perform few location updates, the network serving mobile stations that are invisible to the system can treat these mobile stations as relatively immobile device of.

The preferred embodiment of the present invention adopts at least two levels of location registration methods, namely, location area level registration and cell area level registration. Thus, although registration in conventional systems invokes various forms of location area signaling, the present invention only invokes second-level messages, ie, cell-based registration. According to the mobile behavior of the mobile station, either the positioning area paging operation or the cell area paging operation is adopted.

In traditional systems, the network and the mobile station can know the location of the mobile station. According to a preferred embodiment of the invention, some flag and timer information are added to this knowledge within the mobile station. This flag is set whenever the mobile station selects a new cell without performing a location update. That is, this happens whenever a mobile station is originally registered in a location area and moves to a new cell in the same location area within the same location area. This flag will be set whenever a location update is performed, ie whenever the mobile station moves into a new location area. The timer of the mobile station must be restarted every time the positioning update is performed, and the timer continues to run until a predetermined time value is reached or the positioning update is performed again. The predetermined value timer can be provided by the network, or it can be implemented in the mobile station by means of pre-programming. The network may use a periodic registration timer as the aforementioned predetermined timer.

Figure 1 shows the general environment used by the present invention. The mobile station MS located in the location area 1 can move in various cells in the location area 1, namely cell 1, cell 2...cell 5. According to the existing registration system, as long as a mobile station stays within location area 1, it can move to any cell within location area 1 and still not perform a location update. Then, by way of example only, once an incoming call to a mobile station is received, in order for a paging message to reach a mobile station MS located in one of those particular cells, a call to all cells within location area 1 is required on the paging channel. Send the paging message. Although various methods of drawing location areas (which may overlap, non-overlap, large or small, etc.) area.

As a mobile station moves from a cell in one location area to a cell in another location area (for example, from location area 1 to location area 2, or from location area 2 to location area 3), the mobile station needs to perform a location update so that the network can It is recognized that the mobile station is now located within a new location area.

A preferred embodiment of the present invention is presented in FIG. 2 for various operations performed by a mobile station under various conditions. Boxes 10 and 11 represent the previous location levels identified for a particular mobile station. Block 10 identifies that the mobile station was previously registered on a location area basis (relative to a mobile wireless device), while block 11 indicates that the mobile station was previously registered on a cell basis (relative to a stationary wireless device). The top row of headings in Fig. 2 indicates the environment in which the mobile station can find itself. In Header 12, the mobile station moves into a new cell within the original location area, eg from cell 1 to cell 2 within the same location area 1 (see Figure 1). In heading 15, the mobile station stays in the same cell, but the network reassigns the cell to a new location area, for example in cell 5 given in Fig. 1, at time t=t0, cell 5 is assigned to location Area 1, and then at time t=t1, the cell is assigned to location area 3. In Header 18, the mobile station moves to a new cell and into a new location area, for example from cell 4 of location area 1 of FIG. 1 to cell 7 of location area 2 . Finally in Header 21, the mobile station does not necessarily move to a new cell or a new location area, but recognizes that its timer has expired.

In Fig. 2, blocks 13, 14, 16, 17, 19, 20, 22 and 23 are all taking into account the mobile station's previous registration levels 10 and 11, by the mobile station in various title environments 12, 15, 18 and 21 below the table of operations taken. In this way, a mobile station previously registered on the location area base 10 can perform the following operations:

1) When the mobile station enters a new cell within the original location area (12), the mobile station does not operate (13). This is due to the fact that the mobile station was previously registered on the location area base (10) and has not yet entered the new location area (12).

2) When the mobile station enters a new location area of the same cell (15), the mobile station performs a location update (16). The mobile station was previously updated on a location area basis (10), but the network has rearranged the geographical areas so that the old cells are now located within the new location area. This can happen due to cell redesign. Obviously this doesn't happen every day, but rescheduling cells is a relatively common task in an expanding network.

3) When the mobile station enters a new cell within the new location area, the mobile station performs a location update (19). The reason why the mobile station performs a location update again is that it was previously registered on the location area basis (10) and the mobile station entered a new location area (18).

4) When the mobile station has not entered a new location area or a new cell, but instead recognizes that its timer has expired (21), the mobile station looks at its flag to determine the state of the flag. The flag is set when the mobile station selects a new cell without performing a location update (ie enters a new cell within the original location area). In block 22, if the flag is not set, the mobile station performs a cell-level location update. If the flag is set, no operation is performed.

If the mobile station was previously registered on a cell basis as shown in box 11, when under conditions 12, 15, 18 and 21, the mobile station will react as follows:

1) When the mobile station enters a new cell within the original location area (12), the mobile station performs a location update (14). This is because the mobile station has already started to move at a high speed.

2) When the mobile station stays in the original cell, but the cell is allocated to a new location area (15), the mobile station does not perform operation (17). This is because although the network switches the mobile station into a new location area, it does so because the mobile station was previously registered on a cell basis (11) and remains in the original cell (15).

3) When the mobile station enters a new location area and a new cell (18), the mobile station performs a location update (20). Since the mobile station was previously registered on the cell basis (11), entering a new cell (18) requires a location update (20).

4) When the mobile station recognizes that its timer has expired (21), no action is performed.

In this way, a mobile station can perform different location updates depending on its previous registration level (cell-based or location-area-based) and its new status. The location updates in blocks 14, 16, 19 and 20 are all performed on a location area basis.

In a suboptimal embodiment, the timer used is a periodic registration timer (rather than a mobile-provided internal timer or a network-provided timer). In this case, block 22 would be different. Then in block 22, if the flag is set, the mobile station performs a location update on a location area basis. If the flag in block 22 is not set, the mobile station performs a location update on a cell basis. Also on a periodic registration timer basis, block 23 represents the performance of location updates on a cell basis.

Figures 3 and 4 illustrate flow charts of the preferred embodiment given. In step 30 the mobile station powers up, then in step 31 the mobile station checks its previous location status and location level. Depending on the previous registration level, the previous location level may be cell based or location area based. If the mobile station was previously registered on a location area basis (step 32), the mobile station checks to determine if it is currently within the same location area (step 34). If so (step 36), the mobile station clears the flag (step 42). If not (step 37), the mobile station performs a location area update operation (step 40) and then clears the flag (step 42).

On the other hand, if the mobile station is registered on a cell basis (step 33), the mobile station checks to see if it is still within the original cell (step 35). If yes (step 38), then at step 42 the flag is cleared. If not (step 39 ), a location update is performed on a location area basis (step 41 ), and then at step 42 the flag is cleared.

After step 42 (clearing the flag), the mobile station starts a timer in step 43 and then detects the conditions identified by headers 12, 15, 18 and 21 in FIG. In step 44, the status change of the mobile station is detected, and the following changes are identified in the mobile station: in step 45, the mobile station moves to a new cell (corresponding to block 12 in Fig. 2 ) in the original location area; in step 46 , move to a new cell in the new positioning area (corresponding to block 18 in Figure 2); move to the original cell in the new positioning area in step 47 (corresponding to block 15 in Figure 2); or point A in Figure 3 The given timer expiration state (continued to refer to FIG. 4 ) corresponds to the timer expiration state of block 21 in FIG. 2 . If the mobile station moves to a new cell within the original location area in step 45, it needs to determine its original registration location level in step 48, that is, whether the mobile station is registered on a cell basis or on a location area basis. In step 49, if the mobile station is registered on a cell basis, then in step 51 the mobile station may perform a location update on a location area basis (corresponding to block 14 in Figure 2). The timer can then be restarted at step 52 and the flag cleared at step 53 .

On the other hand, if the mobile station determines in step 48 that its previous registration was performed on the basis of a location area (step 50), this situation corresponds to block 13 in Figure 2, and no action needs to be performed other than In step 54 the flag is set.

At step 44, the mobile station may determine that it has moved to a new cell within the new location area (step 46) (corresponding to block 18 in FIG. 2). In this case (as shown in blocks 19 and 20 in Figure 2), whether the mobile station was previously registered on a location area basis (block 10) or on a cell basis (block 11), It all needs to perform location updates on a location-area basis. Correspondingly in Figure 3, after step 46, the mobile station is to perform a location update on a location area basis (step 55), restart the timer (step 56), and clear the flag (step 57).

If at step 44 the mobile station has been reassigned to the new location area, but still stays in the original cell (step 47) (corresponding to block 15 in Figure 2), then the mobile station determines at step 58 that it was previously Register on the basis of location area, or register on the basis of cell. If the mobile station is registered on a location area basis (step 59) (corresponding to block 16 in Figure 2), the mobile station performs a location update on a location area basis (step 61), restarts the timer (step 62 ), and clear the flag (step 63). On the other hand, if the mobile station determines at step 58 that the previous location registration level was cell-based (step 60), the mobile station takes no action (corresponding to block 17 in FIG. 2). It should be noted that after step 60, the mobile station does not clear the flag since the mobile station has not entered the new cell.

Point A in Fig. 3 is followed by point A in Fig. 4, so that the flow charts in Fig. 3 and Fig. 4 can be regarded as forming a flow chart. Figure 4 shows the situation that occurs when the timer expires (corresponding to block 21 in Figure 2). Generally, after step 44 in FIG. 3, if the mobile station determines that the timer has expired before entering a new cell or entering a new location area, the flow chart will shift to A in FIG. 3 and FIG. 4 point. At step 65, if the mobile station is powered off, the method of operation terminates at step 66. If the timer expires (step 64), given in Figure 2: Depending on the previous registration level 10 or 11, the mobile station either performs a location update or does nothing (box 22 or 23). Thus, the mobile station can determine at step 67 whether the previously registered location class was registered on a location area (block 10 in FIG. 2 ) or cell (block 11 in FIG. 2 ) basis. If it is determined in step 68 that the previous registration was performed on a location area basis, then the operation of block 22 among Fig. ). If it is determined at step 71 that the flag is set, then at step 73 the mobile station restarts the timer and clears the flag (step 74). If on the other hand the flag is not set at the time the timer expires (step 72), then at step 75 the mobile station performs a location update on a cell basis and at step 76 restarts the timer. After steps 74 and 76, the process transfers to step B in FIG. 4 (corresponding to step B in FIG. 3), where in step 44 the process continues to detect the next change of state.

After the timer expires at step 67, if the mobile station detects that its previous registration was on a cell basis (step 69), the mobile station restarts the timer (step 77). Thereafter transfer to point B in Figure 3 to continue the operation.

The timer and flag operations can be integrated in processor circuitry already found in conventional mobile wireless devices. Thus, any mobile wireless device of different types may be employed in accordance with the present invention by adding timer functions, flag functions, and routines consistent with the embodiments described in FIGS. 2-4 to existing processor circuit software. .

The present invention can also be used in other alternative embodiments with more than two registration levels. It is conceivable that there may be other levels between the location area level and the cell level, so that a mobile station moving at a moderate speed can register at a certain geographical level, and this geographical level is between the larger location area and the cell level. between smaller cell levels. In this way, the registration of mobile stations can be performed in a series of levels (each slightly smaller), so that relatively stationary mobile stations can register at the cell level, and mobile stations with increasing speed can be registered at gradually increasing levels. Register on , down to the targeting area level. This latter embodiment is not necessarily preferred, since the benefits of providing additional levels of registration do not balance the added complexity to all systems.

According to the present invention, the rate at which the mobile station has moved in the past can determine how the mobile station performs location updates and how the network responds. The present invention can provide an optimum situation in which, for example, unnecessary loading due to paging of large geographic areas that are not needed can be avoided, but also avoidance of positioning due to requiring all mobile stations to provide location on an unduly frequent basis. Unnecessary load caused by updates.

Referring to the above step 61, when the location area in the cell changes, the mobile device at the location area level is registered at the location area level. Of course, this sounds possible, but a different approach would be to force mobiles to register at the cell level. This advantage is that it can be used when the paging load in the cell is relatively large. In order to immediately reduce the number of paging messages distributed to nearby cells, it can be forced that all mobile devices (in the cell) must be in the cell. level to register. It is very beneficial to use this feature in case of high paging load in a short period of time.

Although the present invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it should be understood that the present invention is not limited to the embodiments presented herein, but rather, the present invention intends It is intended to cover all modifications and equivalent designs included within the spirit and scope of the appended claims.

Claims (19)

1. A method for updating the location of a mobile wireless device within a geographically defined cell or within a geographically defined location area, comprising: a) determining mobility factors associated with the mobile wireless device (31); b) setting timer (43); c) If the mobility factor gives the mobile wireless device a relatively stationary state (33), then: 1) Performing a location update (41) when the mobile wireless device leaves a geographically defined cell (39); 2) When a mobile wireless device is reassigned to a geographically defined location area and enters a new geographically defined location area, but it remains in a geographically defined cell (33), it is prohibited from performing location updates; and d) If the mobility factor gives that the mobile wireless device is in relative motion (34), then: 1) performing a location update (40) when the mobile wireless device leaves a geographically defined location area (37); and 2) When a mobile wireless device leaves a geographically defined cell and enters a new geographically defined cell, but remains within the geographically defined location area (36), it is prohibited from performing location updates. 2. The method of claim 1, further comprising the step of setting a flag whenever the mobile wireless unit leaves the geographically defined cell but does not leave the geographically defined location area. 3. The method according to claim 2, wherein step d) further comprises the steps of: 3) When the timer exceeds the predetermined time (64), check the flag (70), and A) If the flag is set (71), reset the timer (73), and clear the flag (74), and B) If the flag is not set (72), perform a location update (75) on a geographically defined cell area basis and reset the timer (76). 4. according to the method for claim 2, wherein in step d), also comprise the following steps: 3) When the timer exceeds the predetermined time, detect the flag, and A) If the flag is not set, a location update is performed on a geographically defined cell area basis. 5. The method according to claim 4, further comprising a step (42) of clearing the flag after step c1). 6. The method according to claim 4, further comprising a step (42) of clearing the flag after step d1). 7. The method according to claim 4, further comprising the step of clearing the flag after step 3A) of step d). 8. The method according to claim 1, further comprising a step (43) of resetting the timer after step c1). 9. The method according to claim 1, further comprising the step (42) of resetting the flag after step d1). 10. The method of claim 1, wherein step b) includes the step of transmitting the predetermined time to the mobile wireless device. 11. The method according to claim 1, further comprising the step of resetting the timer when the following conditions occur: a) The mobile wireless device is determined to be relatively stationary (33/49) and has entered a geographically defined new cell (45/46); b) The mobile wireless device is determined to be in relative motion (32/59) and has entered a new geographically defined location area (46/47). 12. The method according to one of claims 1-11, wherein after step d), further comprising the steps of: e) Repeat steps a) to d) according to one of the following situations (44): i. The mobile wireless device leaves a geographically defined location area (46/47); ii. The mobile wireless device leaves a geographically defined cell (45/46); and iii. The timer exceeds the predetermined time (64). 13. The method according to claim 1, wherein the location update in steps c1), c2), d1) and d2) is performed on the basis (40/41) of a geographically defined location area. 14. The method according to claim 1, wherein the location update in step c3) is performed on a geographically defined cell basis (75). 15. The method of claim 1, wherein step b) includes obtaining a timer value from a periodic registration timer. 16. The method according to claim 1, wherein in step c), further comprising the steps of: When the timer exceeds a predetermined time (21), a location update is performed (22) on a geographically defined cell basis. 17. The method according to claim 1, wherein said step d) further comprises: 3) performing a location update (55) on a location area basis when the mobile wireless device leaves a geographically defined location area and leaves a geographically defined cell (46); 4) performing a location update on a location area basis (61) when the mobile wireless device leaves a geographically defined location area, but not a geographically defined cell (47); and 5) When a mobile wireless device leaves a geographically defined cell and enters a new geographically defined cell, but remains within said geographically defined location area (45), it is prohibited from performing location updates ( 50). 18. The method according to claim 17, further comprising the steps in step c): When the timer exceeds a predetermined time (21), a location update is performed (22) on a geographically defined cell basis. 19. The method of claim 17, wherein step b) includes obtaining a timer value from a periodic registration timer.

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