WO1995014343A1 - Localisation d'unites mobiles dans un systeme de telephone cellulaire par l'intermediaire de zones virtuelles de localisation - Google Patents

Localisation d'unites mobiles dans un systeme de telephone cellulaire par l'intermediaire de zones virtuelles de localisation Download PDF

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Publication number
WO1995014343A1
WO1995014343A1 PCT/US1993/011171 US9311171W WO9514343A1 WO 1995014343 A1 WO1995014343 A1 WO 1995014343A1 US 9311171 W US9311171 W US 9311171W WO 9514343 A1 WO9514343 A1 WO 9514343A1
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WIPO (PCT)
Prior art keywords
mobile unit
cells
subset
cell
msc
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PCT/US1993/011171
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English (en)
Inventor
David B. Devaney
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Astronet Corp
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Astronet Corp
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Priority to PCT/US1993/011171 priority Critical patent/WO1995014343A1/fr
Publication of WO1995014343A1 publication Critical patent/WO1995014343A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W60/00—Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
    • H04W60/04—Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration using triggered events
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/26—Network addressing or numbering for mobility support

Definitions

  • the invention relates generally to mobile communication systems, and in particular to a system and method for locating mobile units within a cellular telephone system.
  • each cell is defined by a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a radio base station (RBS) having a
  • a centralized mobile switching center connected to all of the RBSs connects the mobile unit's outgoing and incoming calls to and from the public telephone network and to other mobile units.
  • control channel 25 uses a control channel (i.e., a reserved carrier frequency) assigned to the RBS that defines the local cell in which it is currently located.
  • a control channel i.e., a reserved carrier frequency assigned to the RBS that defines the local cell in which it is currently located.
  • the cell in which the mobile unit is currently located is known to the system.
  • the system To handle voice communication, the system generally assigns a voice channel from a plurality of RBS transceivers available in the same cell that corresponds to the control channel.
  • the mobile unit While engaged in a call, the mobile unit often moves beyond the broadcast range of the current cell into the broadcast range of another cell. In this case, the system ordinarily transfers the mobile unit to a voice channel available in the new cell. Accordingly, while engaged in a call the system knows the current cell location of a mobile unit.
  • an activated mobile unit receives information sent by the system on the control channel of the cell in which the mobile unit is currently located.
  • the mobile unit moves beyond the broadcast range of the current control channel, it is designed to search for and re-tune its receiver to the control channel of the cell serving the mobile unit's new location.
  • the mobile unit moves from one cell to another it typically does not transmit information to the new cell.
  • the system therefore does not know the current cell location of a mobile unit that is neither engaged in a call nor in the process of initiating a call.
  • the MSC ordinarily does not know the current cell location of the mobile unit nor does it know the cell control channel to which the mobile unit is currently tuned.
  • the MSC sends control information addressed to that mobile unit on the control channel of every cell in which the mobile unit could possibly be located.
  • the mobile unit recognizes its address on the control channel to which it is currently tuned, it responds to the system on the control channel of that cell and thereby notifies the system of the cell that is currently serving the mobile unit. In other words, the MSC pages the cells of the system until the mobile unit is located.
  • the system sends information on the control channel of each cell indicating when one or more of the mobile units should notify the system of their location.
  • the system can then determine the probable location of a mobile unit based on the time and location of the last report and the anticipated rate of movement.
  • This method is particularly effective in systems covering very large areas with large cells.
  • the time interval between reports must be shortened to accommodate the frequent cell location changes.
  • the proportion of location reports to incoming calls increases, thereby burdening the system with frequent, unnecessary reports which tend to overload the available control channels.
  • This method also burdens the system with periodic reports from mobile units that have not changed their location.
  • cell identification information is sent by each cell on its control channel.
  • the mobile unit reports its location whenever it moves to a cell control channel that is sending different cell location identification information.
  • One well-known type of cell identification occurs when a mobile unit moves from one cellular system to a different system, and the mobile unit receives the system change information and reports its location to the new system.
  • One technique for location-based reporting within the same system includes transmitting location information common to a fixed group of cells, i.e., to a subset of the total number of cells grouped into fixed location areas.
  • the cells are geographically organized into groups of cells having fixed grouping boundaries.
  • each fixed group of cells typically transmits the same group location identification to mobile units therein.
  • mobile units When a mobile unit moves from one group location to another, it reports its new group location to the system.
  • mobile units report their location only when and if they move from the previously reported group location, thereby eliminating unnecessary location reports and allowing the system to know the mobile unit's location to within a fixed group of cells.
  • the number of fixed location areas, and the number of cells in each location area can be adjusted to balance the overhead of registrations (caused by the mobile unit's movement and resultant reporting) against the overhead of paging multiple cells of the group.
  • the greater the amount of paging required to find the mobile unit within its current group while as a fixed group decreases in the number of cells that comprise it, the greater the amount of location reporting resulting from more numerous and frequent crossings of the fixed boundaries. While this system is often able to reduce the system overhead by reducing the total amount of paging in exchange for location reporting, problems arise since the location areas are defined by a set of cells sending common location identification to all mobile units receiving the control channels of these cells.
  • the mobile unit when two adjacent cells in different fixed location areas are sending different location identification information across a fixed boundary, the mobile unit will report its location each time it moves from one cell to the other. Since a mobile unit may repeatedly move between cells in a short period of time, the number of location reports will be excessive. In addition, such numerous registrations tend to quickly drain the batteries on certain types of mobile units (for example, hand-held mobile units with a self- contained power source as opposed to mobile units powered by car batteries) since signal transmission ordinarily consumes more power than does signal reception.
  • the foreign system may be arranged to report the presence of the mobile unit therein to the home system. In this manner, the home system is able to forward incoming calls to the foreign system.
  • the home system is able to forward incoming calls to the foreign system.
  • the mobile unit subsequently reenters a cell in the home system during this time delay, i.e., prior to the home system receiving the notification, it re-registers its presence with the home system.
  • the home system When the home system later receives the notification from the foreign system, the home system concludes that the mobile unit has moved into a cell of the foreign system when in actuality it has just returned. In essence, under these circumstances the location reports are received out of sequence, thereby resulting in the recording of incorrect location information. This results in the mobile unit being "lost" to the home system until a subsequent location registration takes place.
  • Another related object of the invention is to provide a method and system of the above kind wherein each mobile unit has its own virtual location.
  • Still another object is to provide such a method and system wherein the virtual subset groupings are broadcast to the mobile units.
  • Another object is to provide such a method and system wherein the virtual subset groupings are standardized within the mobile units.
  • the invention provides a method and system for locating a mobile unit within a dynamic subset of all of the cells of the system. To this end, information identifying the cell is transmitted from each of the cells in the system, and is received at the mobile unit from a local one of the cells that is the cell within which the mobile unit is located. A transceiver at each RBS is employed to transmit the cell identifying information to a transceiver at the mobile unit.
  • the received cell identity is then compared with the identity of a subset of all of the cells stored in a memory to determine if the identity of the local cell matches the identity of one of the cells in the subset. If there is not a match, the mobile unit registers its location by transmitting information from the mobile unit to the RBS of the local cell to identify and report the presence of the mobile unit within the local cell. The RBS then communicates information to the MSC that locates the mobile unit within the local cell and within the new subset of cells. The identity of the subset of cells stored in the memory is updated with the identities of the cells of a new subset that includes the local cell.
  • a processor is preferably employed to compare the identities of the subset of cells in the memory with the identity of the local cell, and circuitry responsive to the processor informs the RBS of the local cell that the mobile unit is within the cell and also updates the identities of the cells in the subset of cells stored in the memory.
  • the subset is alternatively known as a virtual mobile location area, or the acronym VMLA.
  • Figure 1 illustrates a prior art cellular system wherein subsets of cells are grouped into fixed location areas
  • Fig. 2 illustrates two adjacent cellular systems
  • Fig. 3a is a block diagram illustrating the key components of the cellular system according to the invention
  • Fig. 3b is a pair of state machine diagrams (i) and (ii) representing functions performed by the mobile unit and MSC processing circuitry of Fig. 3a in accordance with received and stored data;
  • Fig. 4 is a representation of a cellular system according to the invention wherein a subset of cells is dynamically assigned to a mobile unit and recorded as its virtual location area;
  • Fig. 5 is a representation of a cellular system according to the invention wherein a mobile unit has traveled to a different cell within the subset of cells assigned in Fig. 4;
  • Fig. 6 is a representation of a cellular system according to the invention wherein a mobile unit has traveled to a different cell out of the subset of cells assigned in Fig. 4 and is assigned a new subset of cells as its virtual location area;
  • Fig. 7 is a representation of an MSC memory area reserved for storing the last reported location of a mobile unit in a cell of the system;
  • Fig. 8 is a representation of an MSC memory area reserved for storing the subset information corresponding to each cell of the system;
  • Fig. 9 is a table of the cell location identification (CLI) codes and system identification (SI) codes broadcast by the RBSs defining the cells of the system to mobile units therein;
  • Fig. 10 is a table of the CLI codes and their corresponding cell identities;
  • Fig. 11 is a representation of the contents of a section of mobile unit memory reserved for recording virtual location subset information
  • Fig. 12 is a flow diagram of the mobile unit software functions for implementing the invention
  • Fig. 13 is a flow diagram of the MSC software functions for implementing the invention.
  • Figs. I4a-14c are representations of the memory contents reserved for recording standardized subset information.
  • Figs. I5a-15c are representations of a cellular system corresponding to Figs. 14a-14c illustrating standardized virtual locations for one of the cells of a system.
  • Figs. 1 and 2 show two systems wherein the cells are subdivided into fixed location groupings.
  • Fig. 1 represents the prior art of dividing groups of cells into fixed location areas within a single cellular system
  • Fig. 2 illustrates two different, but adjacent systems having a fixed boundary therebetween.
  • the previously described problems associated therewith i.e., excessive location reporting, location reports received out-of-sequence, and so on
  • a cellular telephone system having a plurality of cells C 1 -C 34 , corresponding to radio base stations (RBSs) R i - 34 connected to a mobile switching center (MSC) 12.
  • RBSs radio base stations
  • MSC mobile switching center
  • conventional input-output circuitry allowing both voice and data communication between the MSC 12 and each RBS R 3 .- 34 defining a cell ⁇ -0 34 are present.
  • the system of cells may be of any number and be arranged in any desired pattern, and is in no way intended to be limited to the thirty-four cells as illustrated.
  • the mobile unit 20 has a transceiver (TxRx) 22 for communicating with at least one transceiver (TxRx) such as transceiver TxRx 7 of the RBS R 7 (corresponding to cell C 7 ) on a reserved control channel and an assigned voice channel when appropriate.
  • TxRx transceiver
  • the mobile unit 20 comprises conventional circuitry including a processor 24 and memory 26.
  • the MSC 12 also has processing circuitry such as microprocessor 14 and at least one memory storage area 16 associated therewith.
  • the MSC 12 and the RBSs R 1 -R 34 transfer control data between MSC modems 18- ⁇ 18 34 and RBS modems 40 1 -40 34 .
  • conventional system controllers (CTLs) 44 2 -44 34 which may be microprocessors or the like, and memories 42 2 -42 34 are ordinarily incorporated therein.
  • CTLs system controllers
  • the mobile unit 20 occupies a virtual location area associated with its current cell. As best shown in Fig. 4, the mobile unit 20 is currently within cell C 7 .
  • the virtual location area 30 (indicated by cross-hatching) comprises a subset group of cells defined for the current cell C 7 that the mobile unit is within at the time of registration with the system.
  • every other cell of the system may have a subset group of cells previously assigned to it (preferably by the MSC 12) so that whenever a mobile unit registers its presence within a particular cell, the MSC 12 is able to access its memory 16 to determine the identities of the other cells in that particular cell's subset group.
  • the MSC 12 only needs to page the cells of the subset group to locate the mobile station.
  • the MSC 12 once registered with the cell C 7 , the MSC 12 at most only needs to page cells C 3 , c 4, c 6' c 7' 8' c ⁇ i' C 12 and c i 6 to l° ca-te the mobile unit 20. This paging of the subset cells may either be done simultaneously or sequentially until the mobile unit 20 is located.
  • each cell - ⁇ - ⁇ is provided by the MSC 12 with a cell location identifying label (CLI) that may or may not be unique to each cell.
  • CLI cell location identifying label
  • the amount of information that must be transmitted from an RBS to the mobile unit is reduced, since rather than broadcasting an identifier for (i.e., the identity of) each individual cell in the subset, one or more cells may be assigned the same identifying CLI code.
  • cells C- L and C 2 have commonly been assigned a CLI equal to 06
  • cells C 3 and C 7 have commonly been assigned a CLI equal to 02, and so on.
  • a single mobile unit initially becomes operational in cell C 7 (Fig. 4) , travels to cell C 6 (Fig. 5) and thereafter enters cell C 5 (Fig. 7).
  • the system functions as a mobile station 20 becomes active in a cell (such as the cell C 7 ) of the system, for example by being powered-up by a subscriber in that cell.
  • a cell such as the cell C 7
  • the section 26a of the mobile unit memory 26 that is reserved for storing subset information is cleared, either by action taken during the power-up procedure itself or because the memory is cleared as a result of the previous powering-down of the unit 20.
  • the mobile unit 20 can immediately register itself to the current cell C 7 of the system that it is within, however it can also initially register with the system by acting in accordance with the invention as described below.
  • the mobile unit 20 regularly receives (on the control channel of the RBS R 7 corresponding to cell C 7 ) the CLI number assigned to cell C 7 , a CLI equal to "02" and a system identifier (SI) , an "A" code (see Fig. 9) .
  • the mobile unit 20 ordinarily takes no action unless a cell change has been detected (i.e., either during power-up or when the mobile re-tunes its transceiver to a new control channel) .
  • a change in cells is detected, as indicated at step 102 of Fig. 12 and as represented by the state machine in part (i) of Fig.
  • the mobile unit 20 receives and stores in the memory 26a the new CLI list for the subset of cells grouped with current cell C 7 (Fig. 11) .
  • Figure 10 shows the CLI numbers and their corresponding cells for the exemplified embodiment. As shown in Fig. 7 and in steps 120 and 122 of Fig.
  • the MSC 12 receives from the RBS R 7 and records in an MSC memory area 16a the identity of the mobile unit 20 (equal to M20) in conjunction with the present cell (equal to C 7 ) that the mobile unit 20 is within.
  • MSC memory area 16b (Fig. 8) , the MSC 12 has previously recorded the subset information for each cell by storing the CLI list for each cell.
  • cell C 7 has as its corresponding virtual memory location area cells having CLI numbers 02, 05, 03, 04 and 01 as also indicated by the subset of cells of Fig. 4.
  • the list is equivalent to the list stored in the mobile unit memory section 26a as described above.
  • the MSC retrieves the CLI list for cell C 7 and sends it through the RBS R 7 to the mobile unit 20.
  • the retrieval step may be accomplished as represented in the state machine diagram of part (ii) of Fig. 3b by comparing the cell identity C 7 with a list of cells in memory to find the memory location of the appropriate CLI list or by otherwise indexing the memory using cell C 7 .
  • the MSC 12 may have previously downloaded the appropriate CLI list to each RBS R 2 -R 34 of the system which records it in its memory 42 3 ⁇ -42 34 .
  • the MSC needs to realign or update the cell groupings, a subsequent and similar downloading procedure is then executed.
  • the CLI list may be different for different mobiles as described below, (for example based on subscription type) , and therefore with an MSC to RBS downloading procedure the
  • RBS may have to select from among multiple lists, either by its making its own determination or by direction from the MSC. In any case, the RBS transfers the proper CLI list to the mobile unit. After receiving the CLI subset list for cell C 7 , the mobile unit 20 returns to step 100 and either waits until a new cell is entered or alternatively continues to execute the steps symbolized in Fig. 12 while remaining within the cell C 7 . However, unlike the time of the initial comparison when the mobile unit memory area 26a was cleared, the subsequent time that the mobile unit 20 receives a CLI equal to "02" at step 100, the mobile unit will find a match at step 102 since a "02" is stored in the memory area 26a.
  • the procedure then branches to a different routine in order to compare the current system identifier (SI g ) with the received system identifier (SI r ) to ensure that the mobile has not moved into a cell of another system that happens to have a CLI number matching the stored list.
  • SI g system identifier
  • SI r received system identifier
  • the mobile unit 20 As shown in Fig. 5, as the mobile unit 20 travels to a new cell C 6 , again at step 100 it begins to receive cell C 6 's CLI code equal to "05" along with an SI code "A" (see Fig. 9) . Since it has entered a new cell, at step 102, it compares the "05" with the CLI list in its reserved memory area 26a. Since cell C 6 is in the virtual location area defined for cell C 7 , the CLI number received matches one on the stored CLI list, so by agreed standard procedure the mobile unit 20 does not register its presence with the new cell C 6 . Note that the received SI code is still the same "A" code. As shown in Figs.
  • the MSC 12 is aware of the mobile unit 20's general location within the cells of the subset group originally based on cell C 7 and can therefore locate the mobile unit to connect it to an incoming call, for example a call coming from the public telephone network 32 through a telephone interface circuit (TIC) 33, by only paging the few cells of the virtual group, including cell C 6 . Once located, connection is made through the proper RBS in the usual manner.
  • TIC telephone interface circuit
  • the mobile unit 20 can travel back and forth between cells C 6 and C 7 any number of times without having to re-register its location with the system. Likewise, the mobile unit 20 can travel to any of cells c llf C 3 , C 4 , C 8 , C 12 and C 16 without re-registering. In short, only when the mobile unit 20 leaves its virtual location area (the subset group of cells) and enters a new cell that does not belong to the previous subset group is any action required.
  • a new virtual location area is defined for the mobile unit 20, such as the location area depicted in Fig. 6.
  • the mobile unit in the same system cannot ordinarily repeatedly cross a boundary into a cell that is not on its list, requiring registration each time, since once the mobile unit 20 enters an unlisted cell both the current cell and the previous cell typically become part of its new list. For example, even if the mobile unit 20 immediately reenters the cell C 6 after previously crossing the boundary into the cell C 5 , no additional registration takes place. That is because as allocated in this example, cell C 6 belongs to the virtual location area for cell C 7 and also to the virtual location area for cell C 5 .
  • the present invention further provides a procedure to accommodate the system switching situation to minimize the amount of coordination required between the various systems.
  • properly coordinated adjacent systems are arranged to share identical CLI codes on at least some of their bordering cells. If a mobile unit crosses into a new system having the same CLI, no registration is necessary since the former system is able to indirectly locate the mobile in the other system by communicating therewith. However, to minimize the coordination between systems, the mobile automatically registers with the new system if it enters a second cell of the new system. In this manner, only the CLIs of the border cells need to be coordinated and reserved, and adjacent systems are otherwise free to distribute their CLIs as desired.
  • the system identifier (SI) is broadcast along with the CLI number for a cell
  • the current SI is similarly stored (SI, S) ) and compared against any subsequently received Sis (SI (r -) to determine if the system has changed.
  • the mobile unit 20 stores the SI of the system that originally provided the virtual location information (SI, list -).
  • the mobile unit 20 will overwrite at step 106 the stored SI for the former current cell (SI (8) ) with the received SI (SI, r) ) for the new cell before looping back to step 100.
  • SI former current cell
  • SI SI, r
  • the system determines at step 128 if the mobile unit belongs to that system, i.e., it checks to see if the mobile is in its "home" system. If so, nothing further needs to be done for that mobile, as it has already registered its location within in a cell and has received the proper CLI list. If however, the mobile unit does not belong, the
  • the "foreign" MSC determines at step 130 if this is the first time that the mobile unit has registered within its system. If this is the first time, then the foreign MSC notifies at step 132 the home system of the presence of the mobile unit therein. If not, the foreign MSC takes no action since the notification has been previously performed after the initial registration.
  • the various subset groups corresponding to each cell can be realigned by the MSC according to system needs. This can be accomplished in a simple manner by having the MSC change the subset groupings by changing the list and/or the identities of the CLI numbers corresponding to the cells.
  • a line of cells along an expressway can be grouped together at rush hour to minimize registrations, and restored at non-peak hours to a pattern wherein all or most of the cells adjacent the cell wherein registration occurs are grouped together.
  • smaller cells such as in a downtown area may be grouped together a first way during working hours and then grouped differently during commuting or weekend hours.
  • the system can reduce the number of messages transmitted to the mobile units from any cell's control channel by reducing the number of location areas that include that cell. As a tradeoff, this increases the number of messages to the system on that cell since more mobile units will need to re-register upon entering that cell, as it will be stored in fewer of the CLI lists stored in the numerous mobile units' memories.
  • a subset grouping location area based on the characteristics of the type of the mobile unit itself, such as the type of equipment including how much power it has or its modulation.
  • the system can also allocate a virtual location area stored for each particular mobile unit based on its type of subscription or its movement history. If such an arrangement is desired, these parameters are also stored in the MSC memory 16 in conjunction with the mobile unit identification to make the virtual location determination.
  • a set of standards according to the invention wherein the mobile units themselves contain a predetermined limited number of virtual location subset groupings in their memories.
  • the individual subset groupings When considered together for all of the cells in a system, the individual subset groupings constitute a predetermined pattern of the subset cells, i.e., a comprehensive listing of the subset cell arrangement for each cell of the system.
  • both the MSC and the mobile unit have one or more of these predetermined patterns of subset information stored therein.
  • the mobile unit will not need to receive the subset information through its transceiver, but instead has access to the information through a previously written non-volatile memory or the like.
  • the mobile unit will not need to receive the subset information through its transceiver, but instead has access to the information through a previously written non-volatile memory or the like.
  • the current cell identifier needs to be broadcast, since both the MSC and the mobile station would be aware of the standard pattern and know the standard subset cell grouping (such as the CLI list) for each cell.
  • the memory could be initialized with the values of the patterns as part of its power-up procedure, although to do so would require a substantial amount of data transmission.
  • each cell of the system broadcasts its "A" identity, a code identifying which standard pattern is being used (such as standard pattern "001") , its individual cell number, and if so organized, its CLI number.
  • a code identifying which standard pattern is being used such as standard pattern "001”
  • a non-volatile subset memory 26b that for cell C 5 , when standard pattern "001" is in effect, cells C l t C 2 , C 6 , C 9 , C 10 and C 34 automatically belong in the subset of cells defining the location area.
  • cell C 5 is also in the group, however to preserve memory it is unnecessarily repetitive to store it again. Since pattern "001" is a standard pattern, the MSC 12, which is responsible for selecting the pattern in use, is likewise aware of the grouped virtual location area, for example by incorporating memory map 26b into a reserved section of its memory 16.
  • the RBS does not therefore transmit the virtual location areas to the mobile unit 20, the concept is substantially identical to the broadcasting of the VMLAs in that the mobile unit 20 only registers its location with a new cell when the mobile unit 20 leaves the VMLA established during the previous registration. At that time, the cell identification that is being broadcast will not match its VMLA list, causing the registration procedure to occur as previously described. It can be readily appreciated that such standards may easily be developed despite the numerous differences in system sizes and shapes since mobile units in systems having fewer cells will never receive cell number identities in excess of the cells in that system. For example, even if standard "001" has groupings defined for hundreds of cells, it will still function since on smaller systems (such as the thirty-four cell system of the exemplified embodiment) since these systems will never broadcast a cell identity above thirty-four.
  • the mobile units are able to internally adjust their subset list based upon their current cell. Moreover, by providing a certain standard code (or by not providing any standard code at all) the system would still be able to alternatively function by broadcasting the CLI information for each cell as described above. Thus, as shown in Figs. 14b and 15b, if the MSC 12 notifies the RBSs 3 -R 34 that the standard has changed to a 002, the broadcasting of the new standard immediately notifies the mobile unit 20 in cell C 5 that along with cell C 5 , cells C x , C 10 , C 14 and C 18 are in its virtual location area.
  • the mobile unit 20 If the mobile has moved to a cell that was previously in the VMLA but is no longer as a result of the change, (such as cell C 2 -, the mobile unit 20 re-registers as described previously so that it is not lost to the system. As shown in the vertical grouping arrangement of Figs. 14c and 15c, numerous standardized VMLA patterns can be organized and pre-loaded into the memories of mobile units.
  • a method and system for reducing system overhead by locating mobile units within a dynamic subset of cells The amount of paging is balanced against the number of registrations necessary to locate the mobile unit.
  • the method and system locates mobile units within a virtual subset of cells that varies dynamically according to the current location of the mobile unit during registration, which may be dynamically broadcast or previously standardized. Each mobile unit has its own virtual location in a subset of cells of the system determined by its current location.
  • a method and system are provided wherein the system realigns the subset of cells corresponding to each cell to optimize system needs.
  • the method and system facilitates location reporting as mobiles travel between different systems, yet minimizes the coordination required between different systems of cells when locating mobile units in one of the systems.

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
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Abstract

L'invention concerne un procédé et un système pour identifier l'emplacement d'unités mobiles (20) dans un système de téléphone cellulaire (10). Un sous-ensemble de cellules est attribué dynamiquement à une unité mobile sur la base de l'emplacement cellulaire de l'unité mobile au moment de l'enregistrement. L'unité mobile enregistre l'information du sous-ensemble et aussi longtemps que l'unité mobile reste dans une des cellules du sous-ensemble, sa position n'est pas enregistrée à nouveau par le système. Le système est capable de localiser l'unité mobile dans le sous-ensemble de cellules attribuées. Lorsque l'unité mobile entre dans une nouvelle cellule qui n'est pas dans le sous-ensemble de cellules, elle est enregistrée à nouveau par le système qui attribue alors un nouveau sous-ensemble de cellules correspondant à son emplacement dans une nouvelle cellule qui n'appartenait pas au sous-ensemble précédent.
PCT/US1993/011171 1993-11-17 1993-11-17 Localisation d'unites mobiles dans un systeme de telephone cellulaire par l'intermediaire de zones virtuelles de localisation Ceased WO1995014343A1 (fr)

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PCT/US1993/011171 WO1995014343A1 (fr) 1993-11-17 1993-11-17 Localisation d'unites mobiles dans un systeme de telephone cellulaire par l'intermediaire de zones virtuelles de localisation

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PCT/US1993/011171 WO1995014343A1 (fr) 1993-11-17 1993-11-17 Localisation d'unites mobiles dans un systeme de telephone cellulaire par l'intermediaire de zones virtuelles de localisation

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WO1998046035A3 (fr) * 1997-04-10 1999-01-07 Qualcomm Inc Determination de la position d'une unite d'abonne dans un systeme de communication mobile
EP0708571A3 (fr) * 1994-10-17 1999-04-07 AT&T Corp. Méthode et système pour commandes réparties dans un système cellulaire sans fil et dans un système de communication personnel
US5946618A (en) * 1996-11-04 1999-08-31 Qualcomm Incorporated Method and apparatus for performing position-based call processing in a mobile telephone system using multiple location mapping schemes
WO2003009618A1 (fr) * 2001-07-18 2003-01-30 Huawei Technologies Co., Ltd. Procede de reconnaissance pour l'identification d'une cellule primaire lors de la commande de l'emission en diversite avec selection du site

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Publication number Priority date Publication date Assignee Title
EP0708571A3 (fr) * 1994-10-17 1999-04-07 AT&T Corp. Méthode et système pour commandes réparties dans un système cellulaire sans fil et dans un système de communication personnel
US6081715A (en) * 1994-10-17 2000-06-27 Lucent Technologies Inc. Method and system for distributed control in wireless cellular and personal communication systems
US5946618A (en) * 1996-11-04 1999-08-31 Qualcomm Incorporated Method and apparatus for performing position-based call processing in a mobile telephone system using multiple location mapping schemes
WO1998046035A3 (fr) * 1997-04-10 1999-01-07 Qualcomm Inc Determination de la position d'une unite d'abonne dans un systeme de communication mobile
WO2003009618A1 (fr) * 2001-07-18 2003-01-30 Huawei Technologies Co., Ltd. Procede de reconnaissance pour l'identification d'une cellule primaire lors de la commande de l'emission en diversite avec selection du site
US7139576B2 (en) 2001-07-18 2006-11-21 Huawei Technologies Co., Ltd. Primary cell identification method under site selective diversity transmit

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