CA2534167A1 - System of and method for using position, velocity, or direction of motion estimates to support handover decisions - Google Patents
System of and method for using position, velocity, or direction of motion estimates to support handover decisions Download PDFInfo
- Publication number
- CA2534167A1 CA2534167A1 CA002534167A CA2534167A CA2534167A1 CA 2534167 A1 CA2534167 A1 CA 2534167A1 CA 002534167 A CA002534167 A CA 002534167A CA 2534167 A CA2534167 A CA 2534167A CA 2534167 A1 CA2534167 A1 CA 2534167A1
- Authority
- CA
- Canada
- Prior art keywords
- subscriber station
- estimate
- handover
- velocity
- cell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 40
- 230000004044 response Effects 0.000 claims description 21
- 230000000903 blocking effect Effects 0.000 claims 1
- 238000005259 measurement Methods 0.000 description 9
- 230000007704 transition Effects 0.000 description 5
- 230000001960 triggered effect Effects 0.000 description 5
- 230000001413 cellular effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
- H04W36/322—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data by location data
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
- H04W36/324—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data by mobility data, e.g. speed data
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
- H04W36/326—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data by proximity to another entity
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
Abstract
A method of and system for supporting a handover decision in a wireless communication system is described. An estimate of the position, velocity or direction of motion of a subscriber station is obtained. The estimate, or information derived there-from, is then used to support a handover decision.
In one embodiment, an estimate of the velocity of the subscriber station is obtained if the handover rate experienced by the subscriber station exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell. A decision is made to handover the subscriber station to the umbrella cell if the estimate of the velocity of the subscriber station exceeds a threshold. In a second embodiment, one or more estimates of the position, velocity, or direction of motion of the subscriber station are obtained responsive to the subscriber station experiencing a directed retry condition. A decision is made to handover the subscriber station from a serving cell to a target cell if the one or more estimates indicate that (1) the subscriber station is located closer to the target cell than the serving cell; or (2) the subscriber station is moving towards the target cell and away from the serving cell.
In one embodiment, an estimate of the velocity of the subscriber station is obtained if the handover rate experienced by the subscriber station exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell. A decision is made to handover the subscriber station to the umbrella cell if the estimate of the velocity of the subscriber station exceeds a threshold. In a second embodiment, one or more estimates of the position, velocity, or direction of motion of the subscriber station are obtained responsive to the subscriber station experiencing a directed retry condition. A decision is made to handover the subscriber station from a serving cell to a target cell if the one or more estimates indicate that (1) the subscriber station is located closer to the target cell than the serving cell; or (2) the subscriber station is moving towards the target cell and away from the serving cell.
Description
SYSTEM OF AND METHOD FOR USING POSITION, VELOCITY, OR
DIRECTION OF MOTION ESTIMATES TO SUPPORT HANDOVER
DECISIONS
Field of the Invention.
[0001] This invention relates to the fields of position determination and wireless communications, and, more specifically, to the use of position, velocity or direction of 'motion estimates to support handover decisions in wireless communications systems.
Related Art.
DIRECTION OF MOTION ESTIMATES TO SUPPORT HANDOVER
DECISIONS
Field of the Invention.
[0001] This invention relates to the fields of position determination and wireless communications, and, more specifically, to the use of position, velocity or direction of 'motion estimates to support handover decisions in wireless communications systems.
Related Art.
[0002] In wireless communications systems, handover refers to the process whereby the responsibility for providing communications services to a subscriber station is transferred from one network, network entity or network resource to another.
The handover may be a hard handover, i.e., one in which the transition between handling by the servicing network, entity or resource and handling by the target network, entity or resource is abrupt, or a soft handover, i.e., one in which this transition is gradual. Furthermore, the handover may be ,triggered in response to a variety of conditions, such as detection at the subscriber station of a weakening of signal strength of the servicing network, entity or resource relative to that of the target network, entity or resource, or a directed retry condition, pursuant to a blocked call or the like, giving rise to the need for load balancing.
The handover may be a hard handover, i.e., one in which the transition between handling by the servicing network, entity or resource and handling by the target network, entity or resource is abrupt, or a soft handover, i.e., one in which this transition is gradual. Furthermore, the handover may be ,triggered in response to a variety of conditions, such as detection at the subscriber station of a weakening of signal strength of the servicing network, entity or resource relative to that of the target network, entity or resource, or a directed retry condition, pursuant to a blocked call or the like, giving rise to the need for load balancing.
[0003] For example, consider an umbrella cell 100 in a wireless communications system as illustrated in Figure 1. The umbrella cell 100 has one or more micro-level cells 102a, 102b having coverage areas /contained within or at least partially overlapping that of the umbrella cell 100. These micro-level cells are typically added to high congestion areas.within the umbrella cell 100. When a subscriber station is within the coverage area of one of these micro-level cells, it is typically serviced by the base station in the micro-level cell in contrast to that of the umbrella cell to avoid overloading the umbrella cell base station. When a subscriber station is moving within the coverage area of one of these umbrella cells, situations can arise where the number of handovers triggered by the movement of the subscriber station is excessive.
[0004] In Figure 1, for example, a subscriber station within vehicle 104 and moving along path 106 is being serviced by the base station for umbrella cell 100 while at location 108. At about location 110, when the subscriber station transitions into the coverage area of cell 102a, a handover to the base station for cell 102a is initiated.
Then, at about location 112, when the subscriber station transitions into the coverage area of cell 102b, a handover to the base station for cell 102b is initiated.
Then, at about location 114, when the subscriber station transitions back into the coverage area of the umbrella cell 100, a handover to the base station for the umbrella cell is initiated. If the subscriber station is moving at a high rate of speed, these handovers can occur within a very short period of time.
Then, at about location 112, when the subscriber station transitions into the coverage area of cell 102b, a handover to the base station for cell 102b is initiated.
Then, at about location 114, when the subscriber station transitions back into the coverage area of the umbrella cell 100, a handover to the base station for the umbrella cell is initiated. If the subscriber station is moving at a high rate of speed, these handovers can occur within a very short period of time.
[0005] however, a handover is a high priority event . which consumes a substantial amount of network resources or overhead to implement. Consider a handover between two base stations triggered when the communication quality of the servicing base station deteriorates relative to that of the target base station. The resources needed to implement this handover include resources needed to detect the triggering event, resources needed to signal the handover command, and resources needed to handle the acknowledgements between the various network entities involved.
These network entities may include not only the subscriber station and the two base stations, but also the base station controller common to the two stations, and the mobile switching center servicing the base station controller. Therefore, if a subscriber station experiences a high handover rate, i.e., a large number of handovers within a prescribed period of time, the overhead needed to achieve these handovers may unduly burden the network, thereby using resources which could be used for traffic. Note that micro-cells are usually high traffic cells and any extra overhead has significant impact on traffic capacity.
These network entities may include not only the subscriber station and the two base stations, but also the base station controller common to the two stations, and the mobile switching center servicing the base station controller. Therefore, if a subscriber station experiences a high handover rate, i.e., a large number of handovers within a prescribed period of time, the overhead needed to achieve these handovers may unduly burden the network, thereby using resources which could be used for traffic. Note that micro-cells are usually high traffic cells and any extra overhead has significant impact on traffic capacity.
[0006] A similar problem can occur when a subscriber station is located near the coverage areas of two or more cells are not necessarily in an umbrella cell/micro-cell relationship. In this scenario, situations can arise in which excessive and unnecessary handovers are generated. Consider, for example, Figure 2A, which illustrates a subscriber station within vehicle 204 located within an overlapping portion 206 of the coverage areas of cells 202a and 202b. Assume that the subscriber station is being serviced by the base station of cell 202a, and experiences a blocked call while located within the overlapping portion 206. In response, the network initiates a directed retry of the call, which in turn forces a handover of the blocked call to the base station of cell 202b to allow the call to proceed without the need to queue the call.
[0007] If the subscriber station is following a path in which it is traveling towards cell 202a and away from cell 202b, such as the path 208 identified in Figure 2A, the handover will soon be followed by another handover back to cell 202a.
Once again, an excessive number of handovers may be experienced that unduly burden the network.
Once again, an excessive number of handovers may be experienced that unduly burden the network.
[0008] Directed retry may also occur when the subscriber station is not within the overlapping portion of the coverage areas of two cells. Consider Figure 2B, which illustrates a subscriber station within vehicle 204 located within the coverage area of cell 202a but outside the coverage area of cell 202b. Assume the subscriber station experiences a blocked call condition while being serviced by the base station within cell 202a. In response, the network initiates a directed retry of the call, which in turn forces a handover of the blocked call to the neighboring base station having less traffic load, in this case, the base station of cell 202b.
SUMMARY ' i [0009] A method of supporting a handover decision in a wireless communications system is described. The method comprises obtaining an estimate of the position, velocity or direction of motion of a subscriber station, and then using this estimate, or information derived there-from, to support the handover decision.
SUMMARY ' i [0009] A method of supporting a handover decision in a wireless communications system is described. The method comprises obtaining an estimate of the position, velocity or direction of motion of a subscriber station, and then using this estimate, or information derived there-from, to support the handover decision.
[0010] The method rnay occur in response to a triggering event. In one embodiment, the triggering event is a determination that the handover rate experienced by the subscriber station exceeds a threshold. This determination is made while the subscriber station is moving within the coverage area of an umbrella cell.
This determination may in turn be prompted by a handover to a micro-cell at least partially within the coverage area of the umbrella cell. In response, an estimate of the velocity of the subscriber station is obtained. If this velocity estimate exceeds a threshold, a decision is made to handover the subscriber station to the umbrella cell, and a handover back to a micro-cell is blocked, at least for a time.
This determination may in turn be prompted by a handover to a micro-cell at least partially within the coverage area of the umbrella cell. In response, an estimate of the velocity of the subscriber station is obtained. If this velocity estimate exceeds a threshold, a decision is made to handover the subscriber station to the umbrella cell, and a handover back to a micro-cell is blocked, at least for a time.
[0011] In a second embodiment, the triggering event is a directed retry condition. In response to this condition, an estimate of the position, velocity or direction of motion of the subscriber station is obtained. This estimate, or information derived there-from, is then used to support a handover decision.
[0012] In one implementation, one or more estimates are obtained. A decision is made to handover the subscriber station to a target cell if the one or more estimates indicate (1) the subscriber station is located closer to the target cell than the serving cell;
or (2) the subscriber station is moving towards the target cell and away from the serving . cell.
or (2) the subscriber station is moving towards the target cell and away from the serving . cell.
[0013] Other or related systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.
[0015] FIG. 1 illustrates an example of a subscriber station moving within the coverage area of an umbrella cell.
[0016] FIGs. 2A-2B illustrate examples of a subscriber station moving near the coverage areas of two or more cells while experiencing a directed retry condition.
[0017] FIG. 3A illustrates an example of a position determination system which represents an example environment for use of the invention.
[0018] FIG. 3B is a block diagram of an example of a GSM wireless communications system which represents another example environment for use of the invention.
[0019] FIG. 4 is a flowchart of an embodiment of a method of supporting a handover decision with an estimate of the position, velocity or direction of motion of a subscriber station, or information derived there-from.
[0020] FIG. 5 is a flowchart of one embodiment of a method of obtaining a position, velocity or direction of motion estimate in response to a request.
[0021] FIG. 6 is a flowchart of one embodiment of a method of supporting a handover decision for a subscriber station moving within the coverage area of an umbrella cell at a velocity exceeding a threshold.
[0022] FIG. 7 is a flowchart of second embodiment of a method of supporting a handover decision for a subscriber station moving within the coverage area of an umbrella cell at a velocity less than or equal to a threshold.
[0023] FIG. 8 is a flowchart of one embodiment of a method of supporting a handover decision for a subscriber station subject to a directed retry condition.
DETAILED DESCRIPTION
DETAILED DESCRIPTION
[0024] As utilized herein, terms such as "about", "approximately", "substantially" and "near" are intended to allow some leeway in mathematical exactness to account for tolerances that are acceptable in the trade. Accordingly, any deviations upward or downward from the value modified by the terms "about", "approximately", "substantially" or "near" in the range of 1 % to 20% or less should be considered to be .explicitly within the scope of the stated value.
[0025] As used herein, the term "software" includes source code, assembly language code, binary code, firmware, macro-instructions, micro-instructions, or the like, or any combination of two or more of the foregoing.
[0026] The term "memory" refers to any processor-readable medium, including but not limited to RAM, ROM, EPROM, PROM, EEPROM, disk, floppy disk, hard disk, CD-ROM, DVD, or the like, or any combination of two or more of the foregoing,, on which may be stored a series of software instructions executable by a processor.
[0027] The terms "processor" or "CPU" refer to any device capable of executing a series of instructions and includes, without limitation, a general- or special-purpose microprocessor, finite state machine, controller, computer, digital signal processor (DSP), or the like.
[0028] The term "logic" refers to implementations of functionality in hardware, software, or any combination of hardware and software.
[0029] The phrase "base station" (BTS) includes individual sectors.
[0030] The phrase "GPS satellite" includes space vehicles (SVs).
[0031] The phrase "position determination system" means any system for determining the position of a subscriber station in a wireless communications system, and includes position determination systems overlaid onto or integrated into wireless communications systems. Examples include assisted GPS positioning systems, network based positioning systems, and standalone GPS positioning systems.
[0032] The term "subscriber station" includes mobile stations and any portable radio device used in a cellular wireless network.
[0033] The term "wireless communication system" includes any wireless communications system employing any multiple access mode or protocol, such as but not limited to IS-95 (CDMA), CDMA 2000, WCDMA, GSM, and GPRS systems.
[0034] The term "micro-cell" means any cell having a coverage area at least partially within or overlapping that of an umbrella cell, and includes a pico-cell.
[0035] The term "threshold" means any 'threshold and includes, without limitation, static, predetermined, and dynamic thresholds. The term also includes thresholds chosen statically or dynamically by the operator to ensure best network performance.
Example Environment [0036] Figure 3A illustrates an example of a position determination system 300 for estimating the position, velocity or direction of motion of a subscriber station 314 in a wireless communication system. This system is one example of an environment in which systems and methods according to the invention may operate, but it should be appreciated that other environments are possible. Hence, nothing in the description of this example environment should be taken as limiting.
Example Environment [0036] Figure 3A illustrates an example of a position determination system 300 for estimating the position, velocity or direction of motion of a subscriber station 314 in a wireless communication system. This system is one example of an environment in which systems and methods according to the invention may operate, but it should be appreciated that other environments are possible. Hence, nothing in the description of this example environment should be taken as limiting.
[0037] In this system, subscriber station 314 receives signals transmitted by a plurality of sources .302, 304, 306, and 308, visible to a receiver in the subscriber station. As illustrated, the sources may be BTSs, GPS satellites, or combinations of BTSs and GPS satellites. In the example illustrated, sources 302 and 306 are GPS
satellites, and sources 304 and 308 are BTSs.
' [0038] Each of the sources transmits a signal which is modulated with an identification code which uniquely identifies the source. In one implementation, the identification codes are PN codes, which may differ in lengthor periodicity according to the source involved. For IS-95 compliant CDMA systems, the PN code is a sequence of length 32,768 chips which is repeated every 26.67 msec. In current GPS
systems, the PN code is a sequence of length 1,023 chips which is repeated every one millisecond.
In other implementations, the source may be identified by other unique global or local identifiers, such as frequency.
[0039] The signals transmitted by sources 302, 304, 306, and 308 are all received by the subscriber station 314 in the form of a composite signal. The signals may be received directly or through repeaters (not shown).
[0040] A database 312 is accessible to a position determination entity (PDE) 310. In one embodiment, PDE 310 is a serving mobile location center (SMLC).
The database 312 embodies one or more almanacs indicating the current positions of each of the sources in the system 300, whether they be base stations, GPS satellites, or combinations of base,stations and GPS satellites. In the system 300 illustrated in Figure 3, these one or more almanacs indicate the current positions of GPS satellites 302 and 306, and base stations 304 and 308.
[0041] The subscriber station 314 is equipped with a correlator which, either alone or in conjunction with a processor, is configured to derive a time of arrival measurement for one or more of the pilot signals received from the sources. In deriving these time of arrival measurements, the correlator and/or processor may utilize various forms of assistance provided to it by PDE 310, such as search windows and window centers for one or more of the sources 302, 304, 306, and 308.
[0042] The subscriber station 314 then communicates the time of arrival measurements to PDE 310. The PDE 310 utilizes the one or more almanacs embodied in the database 312 to determine the locations of the sources corresponding to the time of arrival measurements. It then determines an estimate of the position, velocity or direction of motion of the subscriber station 314 using known triangulation or trilateration procedures. Once determined, the estimates may be communicated by the PDE 310 to the subscriber station 314 or some other entity. As an alternative to the foregoing, the subscriber station 314 may use the time of arrival measurements to estimate its own position, velocity or direction of motion after accessing the database 312 (through PDE 310) to determine the positions of the signal sources.
[0043] The subscriber station 314 operates within a wireless communications system, an example of which is presented in block diagram form in Figure 3B.
Once again, many other example environments are possible, so nothing in this particular example should be taken as limiting.
[0044] In this 'particular example, the wireless communications system is a GSM
cellular system in which the network coverage area is organized into a plurality of cells, with one or more base stations corresponding to each cell. The base stations in the network are organized into groups, with one or more base stations in a group controlled by a base station controller (BSC). In the example of Figure 3B, n base stations form a group, wherein n is an integer of one or more, and these n base stations are identified with numerals 354a, 354b. All of these n base stations are controlled by BSC
356.
Each base station controller in turn is serviced by a mobile switching center (MSC). In the example illustrated in Figure 3B, BSC 356 is serviced by MSC 360.
[0045] SMLC 310 is also accessible to subscriber station 314 through communication link 362 indicated in phantom in Figure 3B. This communication link is indicated in phantom since the physical communication between the two occurs through one of the base stations 354a, 354b and the BSC 356.
[0046] In the particular example illustrated, SMLC 310 provides assistance to the subscriber station 314 in the form of searching windows and searching centers. The subscriber station 314 utilizes this information to search for and derive time of arrival measurements from one or more of the sources 302, 304, 306, and 308 illustrated in Figure 3A. The subscriber station 314 then communicates these time of arrival measurements to SMLC 310. In response, SMLC 310 determines an estimate of the position, velocity or direction of motion of the subscriber station 314.
[0047] In one example, the SMLC 310 obtains at least four time of arrival measurements from subscriber station 314, each corresponding to a different one of the sources. The SMLC 310 accesses one or more almanacs to determine the current position of each of the sources, and then uses known triangulation or trilateration techniques to solve for four unknowns, the coordinates of the position of the subscriber station, which may be represented as x, y, and z, and system or network time t. The SMLC 310 may then store this information and/or communicate it to another entity, including a network entity, or an external location services client, such as a operator, the police, etc.
[0048] The SMI:C 310 may derive a velocity or direction of motion estimate from two or more solutions. Since system time is provided as a by-product of these solutions, the SMLC 310 may simply determine the displacement of the subscriber station 314 along each of the three coordinate axes, and divide each of the displacements by the time difference to obtain a component for each of the three coordinate axes. Together, the three components define a vector having a magnitude and direction of motion. The magnitude of the vector forms an estimate of the velocity of the subscriber station, while the direction of the vector forms an estimate of the direction of motion of the subscriber station.
[0049] For example, a first solution may yield the parameters x1, y1, z1, and t1, and a second solution may yield the parameters x2, y~, z2 and t2. A velocity vector derived from these parameters is a vector having three values, one for each of the x, y, and z coordinate axes. The x component is (x2-xl)/(t2-tl). The y component is (y2-yl)/(t2-tl). The z component is (z2-z~)/(t2-tl). The magnitude of the vector, which forms the velocity estimate, is the square root of the sum ' of the squares of the three components. The direction of the vector forms the direction of motion estimate.
Embodiments of the Invention [0050] Figure 4 illustrates an embodiment of a method 400 of supporting a handover decision in a wireless communications system. The method comprises steps 402 and 404. Step 402 comprises obtaining an estimate of the position, velocity or direction of motion of a subscriber station. Step 404 comprises using the estimate, or information derived there-from, to support the handover decision.
[0051] The obtaining step may comprise obtaining the estimate from an entity in a position determination system, such as a PDE or SMLC. In one embodiment, illustrated in Figure 5, a request for the estimate is received by the entity in step 502. In response, in step 504, the entity retrieves a stored estimate representing a previously obtained estimate. Then, in inquiry step 506, the entity determines if the stored estimate is sufficiently current to be accurate. If so, in step 50~, the stored estimate is returned to the requestor. If the stored estimate is insufficiently current to be accurate, then in step 510, the entity derives and returns to the requestor an updated estimate. In one embodiment, the entity derives the updated estimate from measurements provided to it by the subscribed station, and then returns this derived estimate to the requestor.
[0052] The step of obtaining the estimate may be performed in response to a triggering event. In one embodiment, the triggering event is a determination that the handover rate of the subscriber station, i.e.,~ the number of handovers experienced by the subscriber station within a prescribed time period, exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell. The determination may itself be prompted by a handover of the subscriber station to a micro-cell at least partially within the coverage area of the umbrella cell. The threshold may be a predetermined threshold or a dynamic threshold.
[0053] An implementation 600 of this embodiment is illustrated in Figure 6. In this implementation, the handover rate of the subscriber station is determined when the subscriber station experiences a handover to a micro-cell at least partially within the coverage area of an umbrella cell. Inquiry step 602 is then performed. In inquiry step 602, it is determined whether the handover rate exceeds a threshold. If not, the method ends. If so, step 604 is performed. Step 604 comprises obtaining an estimate of the velocity of the subscriber station. Inquiry step 606 is then performed. In inquiry step 606, it is determined whether the velocity estimate exceeds a threshold. If note the method terminates. ' If so, step 608 is performed. In step 608, a handover of the subscriber station to the umbrella cell is performed. Step 610 follows step 608. In step 610, a handover back to a micro dell is blocked at least for a time.
[0054] This embodiment~seeks to reduce excessive handovers by detecting when a subscriber station within the coverage area of an umbrella cell is experiencing a high handover rate and is moving at a high velocity. If both these conditions are present, the embodiment implements a handover of the subscriber station to the umbrella cell, and blocks, at least for a time, a handover back to a micro-cell.
[0055] Figure 7 illustrates an embodiment 700 which is triggered by a timeout condition occurring while the subscriber station is within the coverage area of and is being serviced by an umbrella cell. This timeout condition indicates that the subscriber station has not experienced a handover within a prescribed period of time.
[0056] In response, step 704 is performed. Step 704 comprises obtaining an estimate of the velocity of the subscriber station. Inquiry step 706 follows step 704. In inquiry step 706, a determination is made whether the velocity of the subscriber station is less than or equal to a threshold. If not, the method ends. In so, step 708 is performed. In step 708, a handover to a micro-cell is enabled.
[0057] This embodiment may be performed after the subscriber station has been handed over to an umbrella cell pursuant to the method of Figure 6. It seeks to allow the subscriber station to be handed back to a micro-cell (for purposes of load balancing or the like) once the velocity of the subscriber station has sufficiently abated so that the risk of excessive handovers is no longer a problem.
[0058] Figure .8 illustrates an embodiment which is triggered by a directed retry condition which itself is prompted by a blocked call or the like experienced by the subscriber station. In this embodiment, step 804 is performed responsive to the occurrence of the directed retry condition. Step 804 comprises obtaining an estimate of the position, velocity or direction of motion of the subscriber station. Step 806 is then performed. In step 806, the estimate, or information derived there-from, is used to support a handover of the subscriber station. The purpose of the handover is to provide the subscriber station with sufficient network resources so that the blocked call can proceed without the need for a queue.
[0059] In one implementation, one or more estimates relating to the subscriber station are obtained responsive to a directed retry condition. For example, an estimate of the position and the velocity of the subscriber station may be obtained responsive to the occurrence of the directed retry condition. Then, a handover is performed if these estimates indicate (1) the subscriber station is positioned closer to a target cell than the serving cell; andJor (2) the subscriber station is moving towards the target cell and away from the serving cell.
[0060] In one embodiment, a system according to the invention comprises one or more entities configured to perform any of the embodiments, implementations, examples, or variants of the methods which have been described or suggested.
In one implementation, the one or more entities comprise one or more of the entities illustrated in Figure 3B.
[0061] In one example, the one or more entities comprise a base station controller (BSC) and a serving mobile location center (SMLC). The SMLC is configured to receive a request for an estimate of position, velocity or direction of motion of a subscriber station. In response, the SMLC obtains the estimate, and provides it to the BSC, which uses the estimate, or information derived there-from, to support a decision whether to execute an intra-BSC handover, i.e., a handover from one BTS controlled by the BSC to another.
[0062] In a second example, the one or more entities comprise a mobile switching center (MSC) and a SMLC. As before, the SMLC is configured to receive a request for an estimate of position, velocity or direction of motion of a subscriber station. In response, the SMLC obtains the estimate and provides it to the MSC. The MSC then uses the estimate, or information derived there-from, to support a decision whether to execute an inter-BSC handover, i.e., a handover from one BSC
serviced by the MSC to another.
[0063] In one embodiment, the one or more entities are configured to obtain an estimate of position, velocity or direction of motion of a subscriber station by retrieving a stored estimate which is sufficiently current to be accurate, and deriving an updated estimate if the previously stored estimate is insufficiently current to be accurate.
[0064] The one or more entities may be configured to obtain an estimate of position, velocity, or direction of motion of a subscriber station in response to a triggering event. In one embodiment, the triggering event comprises a determination that the handover rate of the subscriber station exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell. The threshold may be a predetermined or dynamic threshold. In one implementation, this determination is prompted by the occurrence of a handover of the subscriber station to a micro-cell. In response, the one or more entities are configured to obtain an estimate of the velocity of the subscriber station, and handover the subscriber station to the umbrella cell if the estimate of the velocity of the subscriber station exceeds a predetermined threshold.
The one or more entities may then block, at least for a time, a handover back to a micro-cell. .
[0065] In one embodiment, the triggering event is a timeout condition which occurs while the subscriber station is within the coverage area of an umbrella cell. In one implementation, the subscriber station is being serviced by the umbrella cell at the time of the timeout condition. In this implementation, the timeout condition indicates that the subscriber station has not experienced a handover within a prescribed period of time.
[0066] In response to this triggering event, the one or more entities are configured to obtain an estimate of the velocity of the subscriber station, and enable handover the subscriber station from the umbrella cell to a micro-cell if the estimate of the velocity of the subscriber station is less than or equal to a threshold.
[0067] In a third embodiment, the triggering event is a directed retry condition prompted by a blocked call or the like experienced by the subscriber station.
In response to this triggering event, the one or more entities are configured to obtain an estimate of ,position, velocity or direction of motion of the subscriber station, and then use the estimate, or information derived there-from, to support a handover decision.
[0068] In one example, a plurality of estimates relating to the subscriber station are obtained, and the handover executed if the estimates indicate (1) the subscriber station is positioned closer to a target cell than the serving cell; or (2) the subscriber station is moving towards the target cell and away from the serving cell.
[0069] While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this invention.
satellites, and sources 304 and 308 are BTSs.
' [0038] Each of the sources transmits a signal which is modulated with an identification code which uniquely identifies the source. In one implementation, the identification codes are PN codes, which may differ in lengthor periodicity according to the source involved. For IS-95 compliant CDMA systems, the PN code is a sequence of length 32,768 chips which is repeated every 26.67 msec. In current GPS
systems, the PN code is a sequence of length 1,023 chips which is repeated every one millisecond.
In other implementations, the source may be identified by other unique global or local identifiers, such as frequency.
[0039] The signals transmitted by sources 302, 304, 306, and 308 are all received by the subscriber station 314 in the form of a composite signal. The signals may be received directly or through repeaters (not shown).
[0040] A database 312 is accessible to a position determination entity (PDE) 310. In one embodiment, PDE 310 is a serving mobile location center (SMLC).
The database 312 embodies one or more almanacs indicating the current positions of each of the sources in the system 300, whether they be base stations, GPS satellites, or combinations of base,stations and GPS satellites. In the system 300 illustrated in Figure 3, these one or more almanacs indicate the current positions of GPS satellites 302 and 306, and base stations 304 and 308.
[0041] The subscriber station 314 is equipped with a correlator which, either alone or in conjunction with a processor, is configured to derive a time of arrival measurement for one or more of the pilot signals received from the sources. In deriving these time of arrival measurements, the correlator and/or processor may utilize various forms of assistance provided to it by PDE 310, such as search windows and window centers for one or more of the sources 302, 304, 306, and 308.
[0042] The subscriber station 314 then communicates the time of arrival measurements to PDE 310. The PDE 310 utilizes the one or more almanacs embodied in the database 312 to determine the locations of the sources corresponding to the time of arrival measurements. It then determines an estimate of the position, velocity or direction of motion of the subscriber station 314 using known triangulation or trilateration procedures. Once determined, the estimates may be communicated by the PDE 310 to the subscriber station 314 or some other entity. As an alternative to the foregoing, the subscriber station 314 may use the time of arrival measurements to estimate its own position, velocity or direction of motion after accessing the database 312 (through PDE 310) to determine the positions of the signal sources.
[0043] The subscriber station 314 operates within a wireless communications system, an example of which is presented in block diagram form in Figure 3B.
Once again, many other example environments are possible, so nothing in this particular example should be taken as limiting.
[0044] In this 'particular example, the wireless communications system is a GSM
cellular system in which the network coverage area is organized into a plurality of cells, with one or more base stations corresponding to each cell. The base stations in the network are organized into groups, with one or more base stations in a group controlled by a base station controller (BSC). In the example of Figure 3B, n base stations form a group, wherein n is an integer of one or more, and these n base stations are identified with numerals 354a, 354b. All of these n base stations are controlled by BSC
356.
Each base station controller in turn is serviced by a mobile switching center (MSC). In the example illustrated in Figure 3B, BSC 356 is serviced by MSC 360.
[0045] SMLC 310 is also accessible to subscriber station 314 through communication link 362 indicated in phantom in Figure 3B. This communication link is indicated in phantom since the physical communication between the two occurs through one of the base stations 354a, 354b and the BSC 356.
[0046] In the particular example illustrated, SMLC 310 provides assistance to the subscriber station 314 in the form of searching windows and searching centers. The subscriber station 314 utilizes this information to search for and derive time of arrival measurements from one or more of the sources 302, 304, 306, and 308 illustrated in Figure 3A. The subscriber station 314 then communicates these time of arrival measurements to SMLC 310. In response, SMLC 310 determines an estimate of the position, velocity or direction of motion of the subscriber station 314.
[0047] In one example, the SMLC 310 obtains at least four time of arrival measurements from subscriber station 314, each corresponding to a different one of the sources. The SMLC 310 accesses one or more almanacs to determine the current position of each of the sources, and then uses known triangulation or trilateration techniques to solve for four unknowns, the coordinates of the position of the subscriber station, which may be represented as x, y, and z, and system or network time t. The SMLC 310 may then store this information and/or communicate it to another entity, including a network entity, or an external location services client, such as a operator, the police, etc.
[0048] The SMI:C 310 may derive a velocity or direction of motion estimate from two or more solutions. Since system time is provided as a by-product of these solutions, the SMLC 310 may simply determine the displacement of the subscriber station 314 along each of the three coordinate axes, and divide each of the displacements by the time difference to obtain a component for each of the three coordinate axes. Together, the three components define a vector having a magnitude and direction of motion. The magnitude of the vector forms an estimate of the velocity of the subscriber station, while the direction of the vector forms an estimate of the direction of motion of the subscriber station.
[0049] For example, a first solution may yield the parameters x1, y1, z1, and t1, and a second solution may yield the parameters x2, y~, z2 and t2. A velocity vector derived from these parameters is a vector having three values, one for each of the x, y, and z coordinate axes. The x component is (x2-xl)/(t2-tl). The y component is (y2-yl)/(t2-tl). The z component is (z2-z~)/(t2-tl). The magnitude of the vector, which forms the velocity estimate, is the square root of the sum ' of the squares of the three components. The direction of the vector forms the direction of motion estimate.
Embodiments of the Invention [0050] Figure 4 illustrates an embodiment of a method 400 of supporting a handover decision in a wireless communications system. The method comprises steps 402 and 404. Step 402 comprises obtaining an estimate of the position, velocity or direction of motion of a subscriber station. Step 404 comprises using the estimate, or information derived there-from, to support the handover decision.
[0051] The obtaining step may comprise obtaining the estimate from an entity in a position determination system, such as a PDE or SMLC. In one embodiment, illustrated in Figure 5, a request for the estimate is received by the entity in step 502. In response, in step 504, the entity retrieves a stored estimate representing a previously obtained estimate. Then, in inquiry step 506, the entity determines if the stored estimate is sufficiently current to be accurate. If so, in step 50~, the stored estimate is returned to the requestor. If the stored estimate is insufficiently current to be accurate, then in step 510, the entity derives and returns to the requestor an updated estimate. In one embodiment, the entity derives the updated estimate from measurements provided to it by the subscribed station, and then returns this derived estimate to the requestor.
[0052] The step of obtaining the estimate may be performed in response to a triggering event. In one embodiment, the triggering event is a determination that the handover rate of the subscriber station, i.e.,~ the number of handovers experienced by the subscriber station within a prescribed time period, exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell. The determination may itself be prompted by a handover of the subscriber station to a micro-cell at least partially within the coverage area of the umbrella cell. The threshold may be a predetermined threshold or a dynamic threshold.
[0053] An implementation 600 of this embodiment is illustrated in Figure 6. In this implementation, the handover rate of the subscriber station is determined when the subscriber station experiences a handover to a micro-cell at least partially within the coverage area of an umbrella cell. Inquiry step 602 is then performed. In inquiry step 602, it is determined whether the handover rate exceeds a threshold. If not, the method ends. If so, step 604 is performed. Step 604 comprises obtaining an estimate of the velocity of the subscriber station. Inquiry step 606 is then performed. In inquiry step 606, it is determined whether the velocity estimate exceeds a threshold. If note the method terminates. ' If so, step 608 is performed. In step 608, a handover of the subscriber station to the umbrella cell is performed. Step 610 follows step 608. In step 610, a handover back to a micro dell is blocked at least for a time.
[0054] This embodiment~seeks to reduce excessive handovers by detecting when a subscriber station within the coverage area of an umbrella cell is experiencing a high handover rate and is moving at a high velocity. If both these conditions are present, the embodiment implements a handover of the subscriber station to the umbrella cell, and blocks, at least for a time, a handover back to a micro-cell.
[0055] Figure 7 illustrates an embodiment 700 which is triggered by a timeout condition occurring while the subscriber station is within the coverage area of and is being serviced by an umbrella cell. This timeout condition indicates that the subscriber station has not experienced a handover within a prescribed period of time.
[0056] In response, step 704 is performed. Step 704 comprises obtaining an estimate of the velocity of the subscriber station. Inquiry step 706 follows step 704. In inquiry step 706, a determination is made whether the velocity of the subscriber station is less than or equal to a threshold. If not, the method ends. In so, step 708 is performed. In step 708, a handover to a micro-cell is enabled.
[0057] This embodiment may be performed after the subscriber station has been handed over to an umbrella cell pursuant to the method of Figure 6. It seeks to allow the subscriber station to be handed back to a micro-cell (for purposes of load balancing or the like) once the velocity of the subscriber station has sufficiently abated so that the risk of excessive handovers is no longer a problem.
[0058] Figure .8 illustrates an embodiment which is triggered by a directed retry condition which itself is prompted by a blocked call or the like experienced by the subscriber station. In this embodiment, step 804 is performed responsive to the occurrence of the directed retry condition. Step 804 comprises obtaining an estimate of the position, velocity or direction of motion of the subscriber station. Step 806 is then performed. In step 806, the estimate, or information derived there-from, is used to support a handover of the subscriber station. The purpose of the handover is to provide the subscriber station with sufficient network resources so that the blocked call can proceed without the need for a queue.
[0059] In one implementation, one or more estimates relating to the subscriber station are obtained responsive to a directed retry condition. For example, an estimate of the position and the velocity of the subscriber station may be obtained responsive to the occurrence of the directed retry condition. Then, a handover is performed if these estimates indicate (1) the subscriber station is positioned closer to a target cell than the serving cell; andJor (2) the subscriber station is moving towards the target cell and away from the serving cell.
[0060] In one embodiment, a system according to the invention comprises one or more entities configured to perform any of the embodiments, implementations, examples, or variants of the methods which have been described or suggested.
In one implementation, the one or more entities comprise one or more of the entities illustrated in Figure 3B.
[0061] In one example, the one or more entities comprise a base station controller (BSC) and a serving mobile location center (SMLC). The SMLC is configured to receive a request for an estimate of position, velocity or direction of motion of a subscriber station. In response, the SMLC obtains the estimate, and provides it to the BSC, which uses the estimate, or information derived there-from, to support a decision whether to execute an intra-BSC handover, i.e., a handover from one BTS controlled by the BSC to another.
[0062] In a second example, the one or more entities comprise a mobile switching center (MSC) and a SMLC. As before, the SMLC is configured to receive a request for an estimate of position, velocity or direction of motion of a subscriber station. In response, the SMLC obtains the estimate and provides it to the MSC. The MSC then uses the estimate, or information derived there-from, to support a decision whether to execute an inter-BSC handover, i.e., a handover from one BSC
serviced by the MSC to another.
[0063] In one embodiment, the one or more entities are configured to obtain an estimate of position, velocity or direction of motion of a subscriber station by retrieving a stored estimate which is sufficiently current to be accurate, and deriving an updated estimate if the previously stored estimate is insufficiently current to be accurate.
[0064] The one or more entities may be configured to obtain an estimate of position, velocity, or direction of motion of a subscriber station in response to a triggering event. In one embodiment, the triggering event comprises a determination that the handover rate of the subscriber station exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell. The threshold may be a predetermined or dynamic threshold. In one implementation, this determination is prompted by the occurrence of a handover of the subscriber station to a micro-cell. In response, the one or more entities are configured to obtain an estimate of the velocity of the subscriber station, and handover the subscriber station to the umbrella cell if the estimate of the velocity of the subscriber station exceeds a predetermined threshold.
The one or more entities may then block, at least for a time, a handover back to a micro-cell. .
[0065] In one embodiment, the triggering event is a timeout condition which occurs while the subscriber station is within the coverage area of an umbrella cell. In one implementation, the subscriber station is being serviced by the umbrella cell at the time of the timeout condition. In this implementation, the timeout condition indicates that the subscriber station has not experienced a handover within a prescribed period of time.
[0066] In response to this triggering event, the one or more entities are configured to obtain an estimate of the velocity of the subscriber station, and enable handover the subscriber station from the umbrella cell to a micro-cell if the estimate of the velocity of the subscriber station is less than or equal to a threshold.
[0067] In a third embodiment, the triggering event is a directed retry condition prompted by a blocked call or the like experienced by the subscriber station.
In response to this triggering event, the one or more entities are configured to obtain an estimate of ,position, velocity or direction of motion of the subscriber station, and then use the estimate, or information derived there-from, to support a handover decision.
[0068] In one example, a plurality of estimates relating to the subscriber station are obtained, and the handover executed if the estimates indicate (1) the subscriber station is positioned closer to a target cell than the serving cell; or (2) the subscriber station is moving towards the target cell and away from the serving cell.
[0069] While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this invention.
Claims (31)
1. A method of supporting a handover decision in a wireless communication system comprising:
obtaining an estimate of position, velocity or direction of motion of a subscriber station; and using the estimate, or information derived there-from, to support the handover decision.
obtaining an estimate of position, velocity or direction of motion of a subscriber station; and using the estimate, or information derived there-from, to support the handover decision.
2. The method of claim 1 wherein the obtaining step comprises:
retrieving a stored estimate and returning the retrieved estimate if sufficiently current to be accurate; and deriving an updated estimate and returning the same if the retrieved estimate is insufficiently current to be accurate.
retrieving a stored estimate and returning the retrieved estimate if sufficiently current to be accurate; and deriving an updated estimate and returning the same if the retrieved estimate is insufficiently current to be accurate.
3. The method of claim 1 wherein the obtaining step is performed in response to a triggering event.
4. The method of claim 1 wherein the triggering event comprises a determination that the handover rate of the subscriber station exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell.
5. The method of claim 4 wherein the obtaining step comprises obtaining an estimate of the velocity of the subscriber station.
6. The method of claim 5 wherein the using step comprises deciding to handover the subscriber station to the umbrella cell if the estimate of the velocity of the subscriber station exceeds a threshold.
7. The method of claim 6 further comprising blocking a handover back to a micro-cell at least for a time.
8. The method of claim 3 wherein the triggering event is a timeout condition occurring while the subscriber station is within the coverage area of an umbrella cell.
9. The method of claim 8 wherein the timeout condition indicates the subscriber station has not experienced a handover within a prescribed period of time.
10. The method of claim 9 wherein the obtaining step comprises obtaining an estimate of the velocity of the subscriber station.
11. The method of claim 10 wherein the using step comprises enabling a handover of the subscriber station to a micro-cell if the estimate of the velocity of the subscriber station is less than or equal to a threshold.
12. The method of claim 3 wherein the triggering event is a directed retry condition.
13. The method of claim 12 wherein the directed retry condition is prompted by a blocked call experienced by the subscriber station.
14. The method of claim 12 wherein the obtaining step comprises obtaining one or more estimates relating to the subscriber station.
15. The method of claim 14 further comprising deciding to perform a handover if the one or more estimates indicate (1) the subscriber station is located closer to a target cell than a serving cell; or (2) the subscriber station is moving towards the target cell and away from the serving cell.
16. A system comprising one or more entities configured to perform any of the methods of claims 1 to 15.
17. The system of claim 16 wherein the one or more entities include a position determination entity.
18. A system for supporting a handover decision in a wireless communication system, the system for supporting comprising one or more entities configured to obtain an estimate of position, velocity or direction of motion of a subscriber station; and use the estimate, or information derived there-from, to support the handover decision.
19. The system of claim 18 wherein the one or more entities are configured to obtain an estimate of position, velocity or direction of motion of a subscriber station by retrieving a stored estimate and returning the same if sufficiently current to be accurate; and deriving an updated estimate and returning the same if the retrieved estimate is insufficiently current to be accurate.
20. The system of claim 18 wherein the one or more entities are configured to obtain an estimate of position, velocity, or direction of motion of a subscriber station in response to a triggering event.
21. The system of claim 20 wherein the triggering event comprises a determination that the handover rate of the subscriber station exceeds a threshold while the subscriber station is within the coverage area of an umbrella cell.
22. The system of claim 21 wherein the one or more entities are configured to obtain an estimate of the velocity of the subscriber station in response to the triggering event, and decide to handover the subscriber station to the umbrella cell if the estimate of the velocity of the subscriber station exceeds a threshold.
23. The system of claim 22 wherein the one or more entities are configured to block a handover back to a micro-cell at least for a time.
24. The system of claim 20 wherein the triggering event comprises a timeout condition indicating the subscriber station has not experienced a handover within a prescribed period of time while the subscriber station is within the coverage area of an umbrella cell.
25. The system of claim 24 wherein the one or more entities are configured to obtain an estimate of the velocity of the subscriber station in response to the triggering event, and enable a handover the subscriber station to a micro-cell if the estimate of the velocity of the subscriber station is less than or equal to a threshold.
26. The system of claim 20 wherein the triggering event is a directed retry condition.
27. The system of claim 20 wherein the one or more entities obtain one or more estimates relating the subscriber station responsive to the triggering event.
28. The system of claim 27 wherein the one or more entities decide to perform a handover if the one or more estimates indicate that (1) the subscriber station is located closed to a target cell than a serving cell; or (2) the subscriber station is moving towards the target cell and away from the serving cell.
29. The system of claim 18 wherein the one or more entities comprise a base station controller and a serving mobile location center.
30. The system of claim 18 wherein the one or more entities comprise a mobile switching center and a serving mobile location center.
31. A system for supporting a handover decision in a wireless communication system comprising:
means for obtaining an estimate of position, velocity or direction of motion of a subscriber station; and means for using the estimate, or information derived there-from, to support the handover decision.
means for obtaining an estimate of position, velocity or direction of motion of a subscriber station; and means for using the estimate, or information derived there-from, to support the handover decision.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/632,400 US7251491B2 (en) | 2003-07-31 | 2003-07-31 | System of and method for using position, velocity, or direction of motion estimates to support handover decisions |
US10/632,400 | 2003-07-31 | ||
PCT/US2004/023302 WO2005013635A1 (en) | 2003-07-31 | 2004-07-19 | System of and method for using position, velocity, or direction of motion estimates to support handover decisions |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2534167A1 true CA2534167A1 (en) | 2005-02-10 |
Family
ID=34104364
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002534167A Abandoned CA2534167A1 (en) | 2003-07-31 | 2004-07-19 | System of and method for using position, velocity, or direction of motion estimates to support handover decisions |
Country Status (6)
Country | Link |
---|---|
US (1) | US7251491B2 (en) |
EP (1) | EP1649716A1 (en) |
JP (1) | JP2007500968A (en) |
CA (1) | CA2534167A1 (en) |
RU (1) | RU2387100C2 (en) |
WO (1) | WO2005013635A1 (en) |
Families Citing this family (73)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6587781B2 (en) * | 2000-08-28 | 2003-07-01 | Estimotion, Inc. | Method and system for modeling and processing vehicular traffic data and information and applying thereof |
US6985731B1 (en) * | 2001-04-02 | 2006-01-10 | Bellsouth Intellectual Property Corporation | Location defined control of cellular system |
US8160020B2 (en) * | 2001-06-25 | 2012-04-17 | Airvana Network Solutions, Inc. | Radio network control |
US8195187B2 (en) | 2001-06-25 | 2012-06-05 | Airvana Network Solutions, Inc. | Radio network control |
AU2003259357B2 (en) * | 2002-08-29 | 2009-08-13 | Inrix Uk Limited | Apparatus and method for providing traffic information |
US8095146B2 (en) * | 2003-09-30 | 2012-01-10 | Lenovo (Singapore) Pte Ltd. | Method and system for directing a wireless user to a location for improved communication |
US7369861B2 (en) * | 2004-02-27 | 2008-05-06 | Nokia Corporation | Methods and apparatus for sharing cell coverage information |
US8639251B2 (en) * | 2004-03-30 | 2014-01-28 | Telefonaktiebolaget Lm Ericsson (Publ) | Methods of and apparatuses for cell-differentiated handover in a mobile communications systems |
US7620402B2 (en) * | 2004-07-09 | 2009-11-17 | Itis Uk Limited | System and method for geographically locating a mobile device |
JP4641791B2 (en) * | 2004-12-15 | 2011-03-02 | パイオニア株式会社 | Remote playback system, remote playback method, and computer program |
EP1908288A2 (en) * | 2005-05-27 | 2008-04-09 | Symbolic Intelligence Enhanced Systems, Inc. | Cellular television broadcast system |
US8099504B2 (en) | 2005-06-24 | 2012-01-17 | Airvana Network Solutions, Inc. | Preserving sessions in a wireless network |
US8457828B2 (en) * | 2005-06-27 | 2013-06-04 | The Charles Machine Works, Inc. | Remote control machine with partial or total autonomous control |
US20060291420A1 (en) * | 2005-06-27 | 2006-12-28 | Dennis Ng | Network-initiated dormant handoffs |
US7751835B2 (en) | 2005-10-04 | 2010-07-06 | Airvana, Inc. | Non-circular paging areas |
CN100459802C (en) * | 2005-10-26 | 2009-02-04 | 华为技术有限公司 | Method and system for implementing cellular communication system switching |
US20070135122A1 (en) * | 2005-12-12 | 2007-06-14 | Dillon Matt J | System and method for providing coverage to mobile stations in a network |
US8094630B2 (en) * | 2005-12-16 | 2012-01-10 | Airvana Network Solutions, Inc. | Radio frequency dragging prevention |
US8145221B2 (en) * | 2005-12-16 | 2012-03-27 | Airvana Network Solutions, Inc. | Radio network communication |
US8619702B2 (en) | 2005-12-16 | 2013-12-31 | Ericsson Evdo Inc. | Radio network control |
JP4705885B2 (en) * | 2006-06-16 | 2011-06-22 | 株式会社日立製作所 | Congestion control method and base station control apparatus for wireless communication system |
US8085696B2 (en) | 2006-07-14 | 2011-12-27 | Airvana Networks Solutions, Inc. | Dynamic modification of route update protocols |
US20080057865A1 (en) * | 2006-09-05 | 2008-03-06 | Broadcom Corporation, A California Corporation | Wireless terminal making attachment decisions based upon mobility |
KR100931902B1 (en) * | 2006-09-05 | 2009-12-15 | 브로드콤 코포레이션 | Wireless terminal making connection determination based on the movement state |
EP2070053A2 (en) * | 2006-09-12 | 2009-06-17 | Itis Holdings PLC | Apparatus and method for implementing a road pricing scheme |
US8626171B2 (en) * | 2006-11-29 | 2014-01-07 | Kyocera Corporation | Wireless communication terminal and method of controlling the same |
US20080167046A1 (en) * | 2007-01-04 | 2008-07-10 | Institute For Information Industry | Method of mobile terminal for handover/switch among different wireless communication networks in a heterogeneous network environment |
US8094605B2 (en) | 2007-03-30 | 2012-01-10 | Livetv, Llc | Aircraft communications system with network selection controller and associated methods |
JP4835499B2 (en) * | 2007-04-18 | 2011-12-14 | 株式会社日立製作所 | Intersystem handoff method and wireless communication terminal |
US8923212B2 (en) * | 2007-08-17 | 2014-12-30 | Qualcomm Incorporated | Method and apparatus for interference management |
GB0719639D0 (en) * | 2007-10-08 | 2007-11-14 | M M I Res Ltd | Method and apparatus for forcing inter-rat handover |
US8843638B2 (en) | 2007-12-13 | 2014-09-23 | Ericsson Evdo Inc. | Handing off active connections |
US20090168725A1 (en) * | 2007-12-26 | 2009-07-02 | Qualcomm Incorporated | Communication handover management |
WO2009107802A1 (en) * | 2008-02-29 | 2009-09-03 | 株式会社エヌ・ティ・ティ・ドコモ | Mobile communication system and network device |
US9544833B2 (en) * | 2008-07-11 | 2017-01-10 | Qualcomm Incorporated | Method and apparatus for femto cell deployment using neighbor list messages and its use in femto cell system selection |
CN101651903B (en) * | 2008-08-12 | 2012-07-18 | 中兴通讯股份有限公司 | Method and terminal for controlling evaluation of terminal motion state |
US20100081888A1 (en) * | 2008-09-30 | 2010-04-01 | Honeywell International Inc. | System and method for monitoring the health of a subject system |
US20100105394A1 (en) * | 2008-10-29 | 2010-04-29 | Qualcomm Incorporated | Methods and systems for selective data communications for multi-mode devices |
GB0901588D0 (en) | 2009-02-02 | 2009-03-11 | Itis Holdings Plc | Apparatus and methods for providing journey information |
US8977282B2 (en) | 2009-03-24 | 2015-03-10 | Qualcomm Incorporated | Multi-channel management and load balancing |
US20100246399A1 (en) * | 2009-03-24 | 2010-09-30 | Qualcomm Incorporated | Multi-channel management and load balancing |
EP2430864B1 (en) * | 2009-05-11 | 2018-02-14 | Sierra Wireless, Inc. | Method and system for performing position updates in a wireless communication system |
WO2011020481A1 (en) * | 2009-08-19 | 2011-02-24 | Nec Europe Ltd. | Method for supporting handover decisions of a mobile terminal in a mobile cellular communication network |
US20110201336A1 (en) * | 2010-02-12 | 2011-08-18 | David Garrett | METHOD AND SYSTEM FOR OPTIMIZING USER-LEVEL QoS DURING A LOCATION-BASED HANDOFF OVER HETEROGENEOUS MOBILE ENVIRONMENTS |
TWI414192B (en) | 2010-03-02 | 2013-11-01 | Ind Tech Res Inst | Handover decision apparatus and method between broadcast and unicast services and the terminal device thereof |
CN102202261B (en) * | 2010-03-23 | 2013-08-28 | 财团法人工业技术研究院 | Decision device and method for handover between broadcast service and unicast service, and terminal device |
US8634826B1 (en) * | 2010-03-26 | 2014-01-21 | Sprint Spectrum L.P. | Use of in-vehicle femtocell as basis to limit operation of in-vehicle wireless communication device |
US8606292B1 (en) | 2010-05-21 | 2013-12-10 | Sprint Spectrum L.P. | Methods and systems for limiting mobile station operation in a group setting |
EP2614669A1 (en) * | 2010-09-07 | 2013-07-17 | Nokia Siemens Networks Oy | Mobility in heterogeneous network environments |
US8880707B2 (en) * | 2010-09-17 | 2014-11-04 | Deutsche Telekom Ag | Heterogeneous network access on devices with one or more network interfaces |
FR2965445A1 (en) * | 2010-09-29 | 2012-03-30 | Alcatel Lucent | METHOD FOR MANAGING RADIO RESOURCES IN A CELL RADIO COMMUNICATION NETWORK INFRASTRUCTURE |
RU2475965C2 (en) * | 2010-11-24 | 2013-02-20 | ОАО "Концерн "Созвездие" | Method to assign radio data in cellular network |
US20120322497A1 (en) * | 2011-06-15 | 2012-12-20 | Microsoft Corporation | Client side cellular handoff prediction |
GB2492369B (en) | 2011-06-29 | 2014-04-02 | Itis Holdings Plc | Method and system for collecting traffic data |
US20130040692A1 (en) * | 2011-08-11 | 2013-02-14 | Mediatek, Inc. | Method of Heterogeneous Network Mobility |
CN103024828B (en) * | 2011-09-20 | 2018-03-09 | 中兴通讯股份有限公司 | Method for processing business, apparatus and system |
EP2688330B1 (en) * | 2012-07-17 | 2014-06-11 | Alcatel Lucent | Method for interference reduction in a radio communication system, processing unit, and wireless access network node thereof |
JP2014039118A (en) * | 2012-08-13 | 2014-02-27 | Ntt Docomo Inc | Mobile communication method, radio base station and mobile station |
CN111586783B (en) * | 2012-12-10 | 2022-07-19 | 索尼公司 | Management device, communication device, motion estimation device, system, method, and medium |
KR102078167B1 (en) | 2013-01-25 | 2020-02-17 | 삼성전자 주식회사 | Method and apparatus to control the mobility for small cell in the mobile communicaion system |
TWI511590B (en) | 2013-03-27 | 2015-12-01 | Wistron Corp | A wireless communication system for improving hand-off of the wireless mobile device according to geographic information and a method for improving hand-off |
CN103298042B (en) * | 2013-05-12 | 2016-02-24 | 南京载玄信息科技有限公司 | The transregional intelligent switch method of multi signal based on Animal Behavior Science and device |
US9872210B2 (en) | 2013-10-16 | 2018-01-16 | At&T Mobility Ii Llc | Adaptive rate of congestion indicator to enhance intelligent traffic steering |
WO2015113305A1 (en) * | 2014-01-30 | 2015-08-06 | Telefonaktiebolaget L M Ericsson(Publ) | Autonomous connection switching in a wireless communication network |
JP6133814B2 (en) * | 2014-04-21 | 2017-05-24 | ソフトバンク株式会社 | Base station, handover management apparatus, mobile communication system, and handover control method |
US10750419B2 (en) * | 2015-02-04 | 2020-08-18 | Qualcomm Incorporated | Methods of efficient handover and reselection to a home ENODEB using user equipment motion |
CN108141807A (en) * | 2015-09-29 | 2018-06-08 | 日本电气株式会社 | Communication system and control method |
US10439867B2 (en) | 2015-12-31 | 2019-10-08 | At&T Intellectual Property I, L.P. | Method and apparatus for optimizing a software defined network configuration |
WO2018010802A1 (en) * | 2016-07-14 | 2018-01-18 | Huawei Technologies Co., Ltd. | A mobile station and method for registering the mobile station to a network |
CN108076488B (en) | 2016-11-14 | 2021-01-05 | 华为技术有限公司 | Method, device and system for cell switching |
KR20220117351A (en) | 2017-03-23 | 2022-08-23 | 프라운호퍼 게젤샤프트 쭈르 푀르데룽 데어 안겐반텐 포르슝 에. 베. | Preemptive handover preparation and tracking/paging area handling and intelligent route selection in a cellular network |
CN108702689B (en) * | 2017-12-22 | 2022-10-25 | 北京小米移动软件有限公司 | Cell access method, device and storage medium |
CN115134883A (en) * | 2022-06-27 | 2022-09-30 | 国网青海省电力公司信息通信公司 | Signal switching method and device and electronic equipment |
Family Cites Families (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5548806A (en) * | 1993-01-25 | 1996-08-20 | Kokusai Denshin Denwa Co., Ltd. | Mobile communication system having a cell structure constituted by integrating macro cells and micro cells |
GB2303024B (en) * | 1995-07-01 | 2000-04-12 | Motorola Ltd | Method for determining handover in a multicellular communications system |
JPH09182143A (en) * | 1995-12-27 | 1997-07-11 | Sony Corp | Terminal equipment |
JP3165391B2 (en) * | 1996-03-22 | 2001-05-14 | 松下電器産業株式会社 | Mobile radio communication system and method for detecting position of mobile station |
GB9608543D0 (en) * | 1996-04-25 | 1996-07-03 | Philips Electronics Nv | Determining routes in a network comprising nodes and links |
FR2754968B1 (en) * | 1996-10-22 | 1999-06-04 | Sagem | LOCALIZABLE CELL MOBILE TELEPHONY TERMINAL |
US6052598A (en) * | 1997-09-30 | 2000-04-18 | At&T Corp | Method for predicting the location of a mobile station in a mobile communications network |
FR2783126B1 (en) * | 1998-09-03 | 2001-03-30 | Cit Alcatel | CHANGING FROM THE MICROCELLULAR LAYER TO THE MACROCELLULAR LAYER IN A TWO-LAYERED CELL OF A TELECOMMUNICATIONS NETWORK |
US6216002B1 (en) * | 1998-05-11 | 2001-04-10 | Ericsson Inc. | Method for selecting base transceiver stations for gathering data to determine a mobile station's location in a wireless network |
US6385454B1 (en) * | 1998-10-09 | 2002-05-07 | Microsoft Corporation | Apparatus and method for management of resources in cellular networks |
AU1435300A (en) | 1998-11-06 | 2000-05-29 | Telefonaktiebolaget Lm Ericsson (Publ) | Use of mobile station positioning for hand-off |
US6370357B1 (en) * | 1998-12-21 | 2002-04-09 | Nortel Networks Limited | Mobile speed estimation for digital cellular radio systems |
US6184829B1 (en) * | 1999-01-08 | 2001-02-06 | Trueposition, Inc. | Calibration for wireless location system |
WO2000065856A1 (en) * | 1999-04-22 | 2000-11-02 | Mitsubishi Denki Kabushiki Kaisha | Mobile communcation device and intermittent reception control method |
US6453168B1 (en) * | 1999-08-02 | 2002-09-17 | Itt Manufacturing Enterprises, Inc | Method and apparatus for determining the position of a mobile communication device using low accuracy clocks |
US6587689B1 (en) | 1999-08-19 | 2003-07-01 | Texas Instruments Incorporated | Multi-sensor assisted cellular handoff technique |
US6711408B1 (en) * | 2000-02-05 | 2004-03-23 | Ericsson Inc. | Position assisted handoff within a wireless communications network |
US6611688B1 (en) * | 2000-02-22 | 2003-08-26 | Ericsson Inc. | Position reporting method for a mobile terminal in a mobile communication network |
US6721567B1 (en) * | 2000-03-30 | 2004-04-13 | Nokia Corporation | Apparatus, and an associated method, for selecting a likely target cell in a cellular communication system |
US6718174B2 (en) * | 2000-10-27 | 2004-04-06 | Qualcomm Incorporated | Method and apparatus for estimating velocity of a terminal in a wireless communication system |
JP3731736B2 (en) * | 2001-08-22 | 2006-01-05 | 株式会社Kddi研究所 | Location information management system |
JP3733336B2 (en) * | 2002-02-26 | 2006-01-11 | 株式会社日立製作所 | Wireless terminal device |
-
2003
- 2003-07-31 US US10/632,400 patent/US7251491B2/en not_active Expired - Fee Related
-
2004
- 2004-07-19 EP EP04757158A patent/EP1649716A1/en not_active Withdrawn
- 2004-07-19 CA CA002534167A patent/CA2534167A1/en not_active Abandoned
- 2004-07-19 JP JP2006521898A patent/JP2007500968A/en active Pending
- 2004-07-19 WO PCT/US2004/023302 patent/WO2005013635A1/en active Application Filing
- 2004-07-19 RU RU2006106230/09A patent/RU2387100C2/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
US7251491B2 (en) | 2007-07-31 |
EP1649716A1 (en) | 2006-04-26 |
RU2006106230A (en) | 2006-08-10 |
JP2007500968A (en) | 2007-01-18 |
US20050026619A1 (en) | 2005-02-03 |
RU2387100C2 (en) | 2010-04-20 |
WO2005013635A1 (en) | 2005-02-10 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7251491B2 (en) | System of and method for using position, velocity, or direction of motion estimates to support handover decisions | |
US7065351B2 (en) | Event-triggered data collection | |
US7254401B2 (en) | Network-based method and system for determining a location of user equipment in CDMA networks | |
RU2362213C2 (en) | Selection of navigation solution, used for establishing location of device in wireless communication system | |
US6681099B1 (en) | Method to calculate true round trip propagation delay and user equipment location in WCDMA/UTRAN | |
US9188659B2 (en) | Methods and network nodes for positioning based on displacement data | |
AU2001237678A1 (en) | Method to calculate true round trip propagation delay and user equipment location in WCDMA/UTRAN | |
EP2425667B1 (en) | Dynamic tag control and fingerprinting event localization | |
JP2013516145A (en) | Coordinated receiver selection for UMTS radio localization | |
JP2013516144A (en) | Coordinated receiver selection for UMTS radio localization | |
EP2005404B1 (en) | Method and system for measuring traffic information in cdma network | |
KR101627506B1 (en) | System and Apparatus for Positioning, and Method therefor | |
US8384595B2 (en) | Position estimation through iterative inclusion of measurement data | |
US8060097B1 (en) | Method and apparatus for intelligent mobile-assisted hard handoff | |
KR20010064729A (en) | Apparatus and method for position location in wireless communication network | |
KR100838471B1 (en) | Apparatus for measuring location of subscriber terminal in synchronous cdma network and method thereof | |
GB2475834A (en) | Handover method in media independent handover based on geographical location |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
EEER | Examination request | ||
FZDE | Discontinued |