WO2013066120A1 - Appareil et procédé permettant d'estimer un état de mobilité - Google Patents

Appareil et procédé permettant d'estimer un état de mobilité Download PDF

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WO2013066120A1
WO2013066120A1 PCT/KR2012/009210 KR2012009210W WO2013066120A1 WO 2013066120 A1 WO2013066120 A1 WO 2013066120A1 KR 2012009210 W KR2012009210 W KR 2012009210W WO 2013066120 A1 WO2013066120 A1 WO 2013066120A1
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Prior art keywords
speed
cell
estimation
cell change
changes
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PCT/KR2012/009210
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English (en)
Inventor
Kang Suk Huh
Ki Bum Kwon
Jae Hyun Ahn
Myung Cheul Jung
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Pantech Co., Ltd.
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Priority claimed from KR1020110113958A external-priority patent/KR20130048993A/ko
Priority claimed from KR1020110114793A external-priority patent/KR20130049652A/ko
Application filed by Pantech Co., Ltd. filed Critical Pantech Co., Ltd.
Publication of WO2013066120A1 publication Critical patent/WO2013066120A1/fr

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    • 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
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • H04W64/006—Locating users or terminals or network equipment for network management purposes, e.g. mobility management with additional information processing, e.g. for direction or speed determination

Definitions

  • the present invention relates to wireless communication and, more particularly, to an apparatus and method for estimating the mobility state of wireless user equipment.
  • 3GPP LTE-Advanced (LTE-A) that is, the evolution of 3GPP LTE, is being discussed.
  • HetNet Heterogeneous Network
  • a macro cell is a large cell having a large coverage as compared with a femto cell and a pico cell, and a femto cell and a pico cell are small cells having small coverages.
  • UE that has accessed an HetNet can perform communication with a specific cell according to a channel environment or a mobility state and may also perform a cell change. For example, UE can break connection with a macro cell due to a deteriorated channel stat in the state in which the UE has accessed the macro cell and access another macro cell or pico cell. Or, for example, while UE is moving in the state in which the UE has accessed a macro cell, the UE can break connection with the macro cell and access another macro cell or pico cell.
  • the number of times that UE has changed cells in estimating the mobility state of the UE can be used as a parameter.
  • HomoNet homogeneous network
  • the number of cell changes is selected only based on cells (e.g., macro cells) having the same form.
  • cells e.g., macro cells
  • the reliability of the number of cell changes can be deteriorated.
  • small cells must be taken into consideration. If the number of cell changes is reliable, the reliability of the Mobility State Estimation (MSE) of UE can be increased. Accordingly, there is a need for a method of estimating a reliable mobility state of UE in an HetNet system.
  • a method of estimating a mobility state a User Equipment comprises receiving cell change parameter including a reference value for estimating the speed of the UE, information about time, the density of small cells or scailing factor from the Base Station (BS); and estimating the speed of the UE based on the cell change parameter and determining whether the mobility state of the UE is a high speed, a medium speed, or a low speed.
  • cell change parameter including a reference value for estimating the speed of the UE, information about time, the density of small cells or scailing factor from the Base Station (BS); and estimating the speed of the UE based on the cell change parameter and determining whether the mobility state of the UE is a high speed, a medium speed, or a low speed.
  • a User Equipment includes receiver receiving cell change parameter including a reference value for estimating the speed of the UE, information about time, the density of small cells or scailing factor from the Base Station (BS); and processor estimating the speed of the UE based on the cell change parameter and determining whether the mobility state of the UE is a high speed, a medium speed, or a low speed.
  • cell change parameter including a reference value for estimating the speed of the UE, information about time, the density of small cells or scailing factor from the Base Station (BS); and processor estimating the speed of the UE based on the cell change parameter and determining whether the mobility state of the UE is a high speed, a medium speed, or a low speed.
  • the reliability of the MSE of UE can be increased by calculating the number of cell changes from which cases not related to the mobility state of UE have been excluded in an HetNet system. That is, UE can perform a cell change more successfully by scaling at least one cell change parameter.
  • the mobility state of UE can be estimated more precisely by calculating the number of cell changes in which small cells and the density of the small cells are taken into consideration or differently calculating the number of cell changes for a macro cell and a small cell in an HetNet system.
  • FIG. 1 is a diagram schematically illustrating a concept of an HetNet, including a macro cell, a femto cell, and a pico cell.
  • FIG. 2 shows a distribution of cells having a variety of coverages in an HetNet.
  • FIG. 3 is a diagram illustrating a method of estimating the mobility state of UE (i.e., Mobility State Estimation (MSE)) in an HetNet according to the present invention.
  • MSE Mobility State Estimation
  • FIG. 4 shows the cell change of UE in the expanded range of a femto cell to which the present invention is applied.
  • FIG. 5 an explanatory diagram illustrating IDC to which the present invention is applied.
  • FIG. 6 shows a cell change (or handover) in which IDC interference has been taken into consideration to which the present invention is applied.
  • FIG. 7 shows the cell change of UE in a non-member CSG cell to which the present invention is applied.
  • FIG. 8 is a flowchart illustrating a method of estimating the mobility state of UE in accordance with an example of the present invention.
  • FIG. 9 is a flowchart illustrating a method of estimating the mobility state of UE in accordance with another embodiment of the present invention.
  • FIG. 10 is a flowchart illustrating a method of a BS estimating the mobility state of UE in accordance with an example of the present invention.
  • FIG. 11 is a block diagram of a BS that controls a cell and UE that communicates with the cell in accordance with an example of the present invention.
  • FIG. 12 is a flowchart illustrating a method of estimating the mobility state of UE in accordance with an example of the present invention.
  • FIG. 13 is a flowchart illustrating a conversion method between the number of cell changes in which only a small cell is taken into consideration and a second estimation speed in accordance with an example of the present invention.
  • FIG. 14 is a flowchart illustrating a method of UE estimating the mobility state of the UE in accordance with an example of the present invention.
  • FIG. 15 is a flowchart illustrating a method of UE calculating the number of cell changes for an estimation time according to the present invention.
  • FIG. 16 is a flowchart illustrating a method of a BS estimating the mobility state of UE in accordance with an example of the present invention.
  • FIG. 17 is a block diagram of a BS which controls a cell and UE communicating with the cell in accordance with an example of the present invention.
  • a wireless communication network is described as a target, and tasks performed in the wireless communication network may be performed in a process in which a system (e.g., a Base Station (BS)) managing the wireless communication network controls the wireless communication network and sends data or may be performed in a terminal accessing the wireless communication network.
  • a system e.g., a Base Station (BS)
  • BS Base Station
  • data service can be provided to indoor and outdoor small-sized areas using pico cells, femto cells, and relays.
  • pico cells may be commonly used in a communication shadow area not covered by only a macro cell or an area that requires a lot of data service, a so-called hotspot.
  • a femto cell may be used in an indoor office or a home.
  • a wireless relay may supplement the coverage of a macro cell.
  • An HetNet including a macro cell, a femto cell, and a pico cell is hereinafter described, for convenience of description, but the HetNet may be configured to include other types of cells.
  • a femto cell is a low-power wireless access point and is an ultra-small size BS for mobile communication that is used in rooms, such as a home or an office.
  • a femto cell can access a mobile communication core network using the DSL or cable broadband of a home or an office.
  • FIG. 1 is a diagram schematically illustrating a concept of an HetNet, including a macro cell, a femto cell, and a pico cell.
  • a macro BS 110, a femto BS 120, and a pico BS 130 operated in the HetNet Each of the macro BS 110, the femto BS 120, and the pico BS 130 has a unique cell coverage.
  • a cell provided by the macro BS 110 is called a macro cell 111
  • a cell provided by the femto BS 120 is called a femto cell 121
  • a cell provided by the pico BS 130 is called a pico cell 131.
  • the femto BS 120 is a low-power wireless access point and an ultra-small sized BS for mobile communication that is used in rooms, such as a home and an office.
  • the femto BS 120 can access mobile communication core network using the DSL or cable broadband of a home or an office.
  • the femto BS 120 is connected to a mobile communication network over a wired network, such as an Internet network.
  • UE within the femto cell can access the mobile communication network or the Internet network through the femto BS 120.
  • the HetNet is illustrated as including a macro cell, a femto cell, and a pico cell, for convenience of description, but the HetNet may be configured to include a relay or other types of cells.
  • FIG. 2 shows a distribution of cells having a variety of coverages in an HetNet.
  • macro cells and small cells are distributed in the horizontal and vertical planes of a meter unit, and the degree of the distribution may be represented by the number of macro cells and small cells.
  • One hexagon indicates a macro cell, and three hexagons (i.e., the macro cells) are collectively called a site.
  • a plurality of small cells is crowded within each macro cell. Small cells may be placed at the edges of a plurality of macro cells.
  • the diameter of one site is about 600 m
  • the diameter of a macro cell is about 300 m
  • the diameter of a small cell is about 20 ⁇ 30 m.
  • FIG. 3 is a diagram illustrating a method of estimating the mobility state of UE (i.e., Mobility State Estimation (MSE)) in an HetNet according to the present invention.
  • the mobility state of UE may include at least one of the moving path of the UE, the estimation speed of the UE, and the estimation speed of the UE. That is, a criterion for the mobility state of UE may be the moving path or speed of the UE.
  • a macro cell1 and a macro cell2 neighbor each other, and a small cell1 and a small cell2 are placed within the macro cell1.
  • UE A and UE B move from the macro cell1 to the macro cell2 at the same (or similar) speed.
  • the UE A move via the small cell1 and the small cell2, and the UE B does not pass through any small cell.
  • the UE A When the UE A moves to the small cell1, the UE A breaks connection with the macro cell1 and may perform a cell change to the small cell1.
  • the UE A may be in idle mode or Radio Resource Control (RRC) connected mode.
  • Idle mode is a state in which the UE does not exchange data with a BS
  • RRC_connected mode is a state in which the UE does not exchange data with a BS.
  • the UE A when the UE A is in idle mode, the UE A may perform cell reselection for the small cell1. As another example of the cell change, when the UE A is in RRC_connected mode, the UE A can perform a handover to the small cell1.
  • the term "cell change" hereinafter may mean that UE of idle mode performs reselection or UE of RRC_connected mode performs a handover. Whatever the UE A is in any mode, the UE A attempts the cell change to the small cell1.
  • the number of cell changes N A of the UE A is increased to 1. For example, in order to increase the number of cell changes effectively, a precondition may be that UE stays in a cell for k seconds or more. Here, k may be 1.
  • the number of cell changes N A is increased to 2.
  • the number of cell changes N A is increased to 3.
  • the number of cell changes N A is increased to 4.
  • the UE B performs a cell change because it moves from the macro cell1 to the macro cell2 without passing through any small cell.
  • the number of cell changes N B of the UE B is increased to 1.
  • the estimation speed of UE is calculated based on the number of times (i.e., the number of cell changes) that UE has performs a cell change per time.
  • the estimation speed of UE is a reference regarding whether the estimation speed is higher or lower than a specific reference value and may be classified into two or more levels.
  • the estimation speed of UE may be classified into two levels: a high speed and a low speed.
  • the estimation speed of UE may be classified into three levels: a high speed, a medium speed, and a low speed.
  • the estimation speed of UE may be classified into three levels: a high speed, a medium speed, a normal speed.
  • the medium speed is an estimation speed when the number of cell changes N exceeds a medium-speed reference value Th M , but does not exceed a high-speed reference value Th H (i.e., Th M ⁇ N ⁇ Th H ) for a specific reference time.
  • the high speed is an estimation speed when the number of cell changes N exceeds the high-speed reference value Th H (i.e., N>Th H ) for a specific reference time.
  • the low speed is an estimation speed when the number of cell changes N does not exceed the medium-speed reference value Th M (i.e., N ⁇ Th M ) for a specific reference time or when the number of cell changes N is not determined to be the medium speed or the high speed for a specific reference time.
  • the low speed may be defined as about 0 ⁇ 30 km/h (0 ⁇ 8.3 m/s)
  • the medium speed may be defined as about 30 ⁇ 60 km/h (8.3 ⁇ 16.6 m/s)
  • the high speed may be defined as about 60 ⁇ 120 km/h (16.6 ⁇ 33.2 m/s).
  • the reason why an error is generated between the real speed of UE and the estimation speed of the UE is that the cases of cell changes not related to the mobility state of the UE in an estimation speed calculation process are not taken into consideration. Accordingly, in order to increase the reliability of the estimation speed of UE calculated based on the number of cell changes, cell changes not related to the mobility state of the UE must be taken into consideration.
  • the present invention is disclosed on condition that the estimation speed of UE has three levels. The present invention may be properly changed even when the estimation speed has a different number of levels.
  • Scenarios that is, cell changes in which the cell change of UE is not related to the mobility state of the UE, are described below.
  • IDC In-Device Coexistence interference
  • the cases that is, the scenario 1 to the scenario 3, generate an error in estimating the mobility state of UE.
  • reliability in a method of estimating the mobility state of UE can be improved.
  • the scope of the present invention is not limited.
  • a method of estimating the mobility state of wireless UE according to the present invention can be applied to the case of a cell change in which the cell change of UE is not related to the mobility state of the UE.
  • the BS can handover the UE to the neighboring cell.
  • the cell that is, the object of handover, may be another BS having the same frequency band (hereinafter referred to as an 'intra-frequency BS'), the same BS or a different BS having a different frequency band (hereinafter referred to as an 'inter-frequency BS), or a BS using a different wireless transmission method (hereinafter referred to as a 'Radio Access Technologies (RAT) BS).
  • a 'intra-frequency BS' the same frequency band
  • 'inter-frequency BS a different BS having a different frequency band
  • a 'Radio Access Technologies (RAT) BS a 'Radio Access Technologies
  • CRE means that the coverage of a micro cell is increased in order to obtain an advantage of the load balancing of a network. If the coverage of a micro cell is increased, the number of UEs that can be accommodated is increased.
  • load balancing may be performed when the traffic load of several cells is inequitably distributed. For example, when over-traffic occurs in a cell, a user can be sent from the cell in which over-traffic has occurred to another cell through a handover or a cell reselection method.
  • FIG. 4 shows the cell change of UE in the expanded range of a femto cell to which the present invention is applied.
  • the pico cell expands from the existing range 121 of the pico cell to the new range 122 of the pico cell by performing CRE.
  • UE 200 placed in an expanded range 125 between the existing range 121 and the new range 122 of the pico cell receives service from the macro BS 110 of a macro cell before performing the CRE, but receives service from the pico BS 120 of the pico cell after performing the CRE.
  • UE of RRC_connected mode performs CRE. Accordingly, UE of RRC_connected mode after performing CRE receives service from the pico BS 120, whereas UE of idle mode receives service from the macro BS 110.
  • the UE placed in the expanded range 125 according to the execution of the CRE changes from idle mode to RRC_connected mode, there is no change in the mobility state of the UE, but the UE performs a cell change (or handover) from a pico cell to a macro cell.
  • the cell change that is performed by the UE in the expanded range 125 is a cell change not related to the mobility state of the UE. Accordingly, in order to estimate a reliable mobility state of the UE, it is necessary to calculate the number of cell changes from which cases not related to the mobility state of UE have been excluded.
  • FIG. 5 an explanatory diagram illustrating IDC to which the present invention is applied.
  • UE 200 includes an LTE RF 201, a GPS RF 202, and a bluetooth (BT)/WiFi RF 203.
  • Transmission and reception antennas 204, 205, and 206 are connected to the respective RFs 201, 202, and 203. That is, various types of RFs are closely mounted on one device platform.
  • the transmission power of one RF may be very greater than a reception power level to another RF receiver.
  • the transmission signal of any RF may generate significant interference in the receivers of other RFs within the device.
  • (a) is an example in which the transmission signal of the LTE RF 201 generates IDC interference with the GPS RF 202 and the BT/WiFi RF 203
  • (b) is an example in which the transmission signal of the BT/WiFi RF 203 generates IDC interference with the LTE RF 201.
  • ISM Industrial, Scientific and Medical
  • FIG. 6 shows a cell change (or handover) in which IDC interference has been taken into consideration to which the present invention is applied.
  • an a 600 indicates the Reference Signal Received Quality (RSRQ) of a BS A measured by UE before IDC interference was generated according to a change in the distance
  • an a' 610 indicates the RSRQ of the BS A measured by the UE after IDC interference was generated according to a change in the distance
  • b 620 indicates the RSRQ of a BS B measured by the UE according to a change in the distance.
  • the UE initiates a procedure for performing a cell change (or handover) from the BS A to the BS B at the position of an M 650, that is, a point at which the RSRQ of the BS B is greater than the RSRQ of the BS A by a predetermined measurement report reference value.
  • the RSRQ of the BS A becomes equal to the RSRQ of the BS B at a point at which the a' 600 meets the b 620.
  • the UE initiates a procedure for performing a cell change (or handover) from the BS A to the BS B at the position of an M' 660, that is, a point at which the RSRQ of the BS B is greater than the RSRQ of the BS A in which the IDC interference has been taken into consideration by a predetermined measurement report reference value. That is, if IDC interference exists, the UE that stops as the position of M' also performs a cell change.
  • the cell change performed by the UE at the position of the M' is a cell change not related to the mobility state of the UE. Accordingly, in order to estimate a reliable mobility state of UE, it is necessary to calculate the number of cell changes from which cases not related to the mobility state of the UE have been excluded.
  • a femto cell distinguishes a registered user from an unregistered user and can permit only a registered user to access thereto.
  • a cell which permits only a registered user to access thereto is called a Closed Subscriber Group (hereinafter referred to as a 'CSG').
  • a cell which permits a common user to access thereto is called an Open Subscriber Group (hereinafter referred to as an 'OSG').
  • a CSG cell is a femto cell, that is, a small cell, and is placed within a macro cell.
  • a CSG cell is installed and used within a home or a small office.
  • Each CSG has a unique identifier, and this identifier is called a CSG identity (ID).
  • ID UE may have a list of CSGs to which the UE belongs, and the list of CSGs is also called a white list.
  • the inclusion of a CSG corresponding to a CSG ID in the white list of UE that has read a CSG ID means that the UE is a member of a corresponding CSG cell, and thus the UE is considered as a cell which can access the CSG cell.
  • the CSG cell permits UE to access thereto only when the ID of the UE is included in the access control list of the CSG cell.
  • a non-member CSG cell is a cell in which the ID of the CSG cell is not included in the CSG white list of UE and is a cell in which the ID of the UE is not included in the access control list of the non-member CSG cell. That is, the UE refers to a cell not having a membership to the non-member CSG cell. Here, the UE cannot receive service through wireless access to the non-member CSG cell.
  • FIG. 7 shows the cell change of UE in a non-member CSG cell to which the present invention is applied.
  • a macro BS supports a first frequency f1 and a second frequency f2 and includes CSG cells which transmit service using the first frequency band within a macro cell.
  • the CSG cell is a non-member CSG cell in which UE does not have a membership. It is assumed that the first frequency band has higher priority than the second frequency band.
  • the UE cannot receive the service from the macro BS through the first frequency band because it does not have a membership to the non-member CSG cell. This is because interference is generated in the first frequency band.
  • the UE receives service from the macro BS through the second frequency band in which interference is not generated. That is, the UE performs a cell change (or handover) from the first frequency band to the second frequency band.
  • the cell change from the first frequency band to the second frequency band is a cell change not related to the mobility state of the UE. Accordingly, in order to estimate a reliable mobility state of UE, it is necessary to calculate the number of cell changes from which cases not related to the mobility state of the UE have been excluded.
  • the UE receives service again from the macro BS through the first frequency band having high priority. That is, the UE performs a cell change (or handover) from the second frequency band to the first frequency band.
  • the cell re-change from the second frequency band to the first frequency band is a cell change not related to the mobility state of the UE. Accordingly, in order to estimate a reliable mobility state of UE, it is necessary to calculate the number of cell changes from which cases not related to the mobility state of the UE have been excluded.
  • a method of estimating the mobility state of UE according to the present invention is described below.
  • the reason why the mobility state of UE is estimated is that the UE may derive a new cell change parameter that enables a cell change to be performed more successfully by scaling Q hyst , T reselection , and a Time To Trigger (TTT), that is, cell change parameters, based on an estimation value for the mobility state of the UE.
  • TTT Time To Trigger
  • the cell change parameter is control information that is used to reduce a cell change failure when UE performs a cell change from a current cell to another cell.
  • Q hyst is a value that controls the good and bad of a relative wireless state with a new cell while the value is added to or subtracted from a value indicating that the good or bad of the wireless state of a current.
  • T reselection is the time that a new cell must maintain a better wireless state than a current in order for UE of idle mode to reselect a new cell.
  • the TTT is a parameter that enables UE to enter a handover preparation stage, such as the start of a measurement report, when a wireless state is maintained for the TTT after the wireless state of a new cell is higher than that of a current cell by a specific reference value or higher.
  • the UE scales T reselection and the Q hyst value so that they are reduced in order to perform cell reselection rapidly. If the estimation speed is the low speed, UE scales T reselection and the Q hyst value so that they are increased. Meanwhile, if the estimation speed of UE of RRC_connected mode is the high speed, the UE scales the TTT in such a way as to be reduced so that handover is rapidly performed. If the estimation speed is the low speed, the UE scales the TTT so that it is increased.
  • a BS informs UE of scaling factors corresponding to respective speed levels so that the UE may scale T reselection , Q hyst, and the TTT according to the estimation speed of the UE.
  • FIG. 8 is a flowchart illustrating a method of estimating the mobility state of UE in accordance with an example of the present invention.
  • UE receives at least one cell change parameter from a BS at step S800.
  • the cell change parameter may be received through a different type of a message according to the mode of the UE. For example, if the UE is in RRC_connected mode, the cell change parameter may be transmitted through an RRC connection reconfiguration message. For another example, if the UE is in idle mode, the cell change parameter may be transmitted through a System Information Block (SIB). In particular, the cell change parameter may be transmitted through an SIB type3 information message.
  • SIB System Information Block
  • the cell change parameter is a parameter, that is, a basis for estimating the mobility state of UE.
  • the UE determines whether the estimation speed of the UE is the high speed, a medium speed, or a low speed based on the cell change parameter.
  • the cell change parameter received from the BS is a value defined in a corresponding system and may be transmitted by the BS of a macro cell or the BS of a pico cell.
  • the cell change parameter is control information that is used to reduce a cell change failure when the UE performs a cell change from a current cell to another cell.
  • the cell change parameter may be differently defined according to the mode of UE (i.e., idle mode or RRC_connected mode).
  • the cell change parameter may include Q hyst , T reselection , a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , a low-speed determination time, or the density of small cells.
  • the cell change parameter may include a medium-speed reference value Th M and a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of UE , a low-speed determination time, the density of small cells, and a scaling factor.
  • Each of the medium-speed reference value and the high-speed reference value may be an integer value ranging from 1 to M.
  • M may be 16.
  • M may be 16.
  • the first estimation speed is the high speed.
  • the estimation time may have a value, such as 30 seconds, 60 seconds, 180 seconds, or 240 seconds.
  • the first estimation speed means the speed that is estimated based on only the number of cell change between a macro cell and a macro cell.
  • the UE accumulatively increases the number of cell changes until the estimation time expires. For example, if the estimation time is 60 seconds, the UE increases the number of cell changes every cell change. When the estimation time becomes 60 seconds, the UE calculates the first estimation speed from the number of cell changes at that point of time.
  • the low-speed determination time is a specific time value determined as the low speed when the first estimation speed of the UE is not determined as the medium speed or the high speed, and it may have a value, such as 30 seconds, 60 seconds, 180 seconds, or 240 seconds.
  • the cell change parameter may include a medium-speed reference value Th M and a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of UE , a low-speed determination time, or a scaling factor.
  • the cell change parameter may further include the density of small cells.
  • the scaling factor is a value that is multiplied so that T reselection may be scaled or a value that is added so that Q hyst may be scaled according to the estimation speed of UE.
  • the scaling factor may have a different value according to the level of the speed of UE. If the estimation speed of UE of idle mode is the high speed, the UE scales T reselection and a Q hyst value in such a way as to be reduced so that cell reselection may be performed rapidly. If the estimation speed is the low speed, the UE scales T reselection and a Q hyst value so that they are increased.
  • the scaling factor of Q hyst that scales Q hyst may be -6 dB, -4 dB, -2 dB or 0 dB.
  • the scaling factor of each Q hyst may be set so that it corresponds to any one of the estimation speeds, that is, the high speed, the medium speed, and the low speed.
  • the following table is an example of the scaling factors of Q hyst corresponding to the estimation speeds.
  • the scaling of Q hyst is performed by adding a scaling factor to Q hyst as in Equation below.
  • the scaling factor of T reselection that scales T reselection may be 0.25, 0.5, 0.75, or 1.
  • the scaling factor of each T reselection may be set so that it corresponds to any one of the final estimation speeds: the high speed, the medium speed, and the low speed.
  • the following table shows an example of the scaling factor of T reselection corresponding to the final estimation speed.
  • the scaling of T reselection is performed by multiplying T reselection by a scaling factor as in Equation below.
  • Equation 2 a new T reselection into which the final estimation speed has been incorporated is obtained by multiplying an old T reselection by a scaling factor.
  • each of the medium-speed reference value and the high-speed reference value included in the cell change parameter may be an integer value ranging from 1 to M.
  • M may be 16.
  • the estimation speed is the low speed.
  • the estimation speed is the medium speed.
  • the estimation speed is the high speed.
  • the estimation time taken to estimate the speed of UE may have a value, such as 30 seconds, 60 seconds, 180 seconds, or 240 seconds.
  • the UE accumulatively increases the number of cell changes until the estimation time expires. For example, when the estimation time is 60 seconds, the UE increases the number of cell changes every cell change. When the number of cell changes reaches 60 seconds, the UE calculates a first estimation speed from the number of cell changes at that point of time.
  • a low-speed determination time is a specific time value determined as a low speed when the first estimation speed of the UE is not determined as the medium speed or the high speed, and it may have a value, such as 30 seconds, 60 seconds, 180 seconds, or 240 seconds.
  • the UE may use a timer that operates until an estimation time expires (hereinafter referred to as an "estimation timer").
  • the low-speed determination time is a specific time value at which the speed of UE is determined as a low speed when the estimation speed of UE is not determined as a medium speed or a high speed for a specific time, and it may have a value, such as 30 seconds, 60 seconds, 180 seconds, or 240 seconds.
  • the cell change parameter may include a TTT, a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , or a low-speed determination time.
  • the cell change parameter may further include the density of small cells.
  • the TTT is a parameter that enables UE to enter a handover preparation stage, such as the start of a measurement report, when a wireless state is maintained for the TTT after the wireless state of a new cell is higher than that of a current cell by a specific reference value or higher.
  • the scaling factor is a value that is multiplied so that a TTT may be scaled according to the estimation speed of UE.
  • the scaling factor may have a different value depending on the level of the speed of UE. If the estimation speed of UE of RRC_connected mode is the high speed, the UE scales a TTT in such as a way as to be reduced so that a handover is performed rapidly. If the estimation speed is the low speed, the UE scales a TTT in such as a way as to be increased.
  • a scaling factor that scales the TTT may be 0.25, 0.5, 0.75, or 1.
  • Each scaling factor may be set so that it corresponds to any one of the estimation speeds: the high speed, the medium speed, and the low speed.
  • the following table shows an example of the scaling factors of the TTT corresponding to the estimation speeds.
  • the scaling of a TTT is performed by multiplying TTT by a scaling factor as in Equation below.
  • Equation 3 a new TTT in which an estimation speed has been incorporated by multiplying an old TTT by a scaling factor.
  • the UE that has received the cell change parameter performs a cell change based on the cell change parameter at step S805.
  • UE of idle mode detects cell selection (or cell reselection)
  • UE of RRC_connected mode detects a handover.
  • a scaling factor value may be applied to the cell change parameter according to the mobility state of UE estimated for the old estimation time. That is, UE of idle mode scales a Q hyst value and a T reselection value as in Equation 1 and Equation 2 using the scaling factor values of Table 1 and Table 2. UE of RRC_connected mode scales a TTT value as in Equation 3 using the scaling factor values of Table 3.
  • the UE determines whether the performed cell change is a cell change not related to the mobility state of the UE (hereinafter referred to as a 'UE mobility irrelevance cell change') or not at step S810. If the performed cell change corresponds to one of embodiments 1 to 4 below, the UE determines that the performed cell change is a UE mobility irrelevance cell change that is not related to the mobility state of the UE. Additionally, when the UE of RRC_connected mode receives service from a pico cell in a cell expansion range and changes to idle mode, the UE may perform cell reselection from the pico cell to a macro cell. The UE of idle mode may perform cell reselection with a non-member CSG cell from a first frequency band to a second frequency band or may perform cell reselection from a second frequency band to a first frequency band.
  • the UE determines that the performed cell change is a UE mobility irrelevance cell change when mode is changed from idle mode to RRC_connected mode (embodiment 1).
  • the UE determines that the performed cell change is a UE mobility irrelevance cell change performed when a difference between the measured RSRQ of a source BS and the RSRQ of a target BS complies with a predetermined handover condition (embodiment 2).
  • UE receives service from a macro BS through a first frequency band f1 and a second frequency band f2 as in FIG 7 (here, the first frequency band has higher priority than the second frequency band) and the UE does not have a membership to a CSG cell that uses the first frequency band within the macro cell (i.e., a non-member CSG cell). For example, if the UE that receives service from the macro BS through the first frequency band moves to the non-member CSG cell range and then performs a cell change in order to receive the service through the second frequency band, the UE determines that the performed cell change is a UE mobility irrelevance cell change (embodiment 3).
  • the UE determines that the performed cell change as a UE mobility irrelevance cell change (embodiment 4).
  • the UE calculates the sum of the number of cell changes (i.e., the number of cell changes other than UE mobility irrelevance cell changes) related to the mobility state of UE for an estimation time at step S815.
  • the UE may calculate the sum of the number of cell changes using a "cell change number counter". If the cell change of the UE is not a UE mobility irrelevance cell change, the UE increases the cell change number counter by 1. If the cell change of UE is a UE mobility irrelevance cell change, the UE does not increase the cell change number counter. The UE calculates the sum of the number of cell changes other than UE mobility irrelevance cell changes by applying the cell change number counter to all performed cell change.
  • the UE determines whether an estimation timer has expired or not at step S820. That is, the UE determines whether a predetermined mobility state estimation time of the UE has expired. If, as a result of the determination, the estimation timer has not expired, the UE performs a cell change again at step S805, determines whether the performed cell change is a UE mobility irrelevance cell change, and calculates the sum of the number of cell changes related to the mobility state of UE.
  • the UE updates a result of the estimation for the mobility state of the UE based on the cell change number counter at step S825.
  • the UE updates the existing mobility speed estimation result to a new mobility speed estimation result based on the sum of the number of cell changes for an estimation time.
  • the UE may select a scaling factor corresponding to a result of the updated mobility speed estimation (not shown).
  • UE of idle mode may select the scaling factors of Q hyst and T reselection according to Table 1 and Table 2.
  • UE of RRC_connected mode may select the scaling factor of a TTT according to Table 3.
  • the UE may scale the cell change parameter as the selected scaling factor (not shown).
  • a new cell change parameter is derived by the scaling of the cell change parameter.
  • UE of idle mode calculates the new scaling factors of Q hyst and T reselection by scaling the scaling factors of Q hyst and T reselection according to Equation 1 and Equation 2.
  • UE of RRC_connected mode calculates a new TTT by scaling the scaling factor of the TTT according to Equation 3.
  • the calculation of the estimation speed is illustrated as being performed by UE in FIG 8, it may also be performed in a BS that controls a macro cell.
  • FIG. 9 is a flowchart illustrating a method of estimating the mobility state of UE in accordance with another embodiment of the present invention.
  • UE receives at least one cell change parameter from a BS at step S900.
  • the cell change parameter may be received through a different type of a message according to the mode of the UE. For example, if the UE is in RRC_connected mode, the cell change parameter may be received through an RRC connection reconfiguration message. For another example, if the UE is in idle mode, the cell change parameter may be received through an SIB. In particular, the cell change parameter may be received through an SIB type3 information message.
  • the UE that has received the cell change parameter performs a cell change based on the cell change parameter at step S905.
  • UE of idle mode performs cell reselection, or UE of RRC_connected mode performs a handover.
  • the UE may apply a scaling factor value to the cell change parameter according to the mobility state of the UE estimated for an old estimation time. That is, UE of idle mode scales a Q hyst value and a T reselection value as in Equation 1 and Equation 2 using the scaling factor values of Table 1 and Table 2, and UE of RRC_connected mode scales a TTT value as in Equation 3 using the scaling factor values of Table 3.
  • the UE determines whether the performed cell change is a UE mobility irrelevance cell change or not at step S910. If, as a result of the determination, the performed cell change corresponds to one of the embodiments 1 to 4, the UE determines that the performed cell change is a UE mobility irrelevance cell change not related to the mobility state of the UE.
  • the UE determines whether an estimation timer has expired or not at step S915. That is, the UE determines whether a predetermined mobility state estimation time has expired. If, as a result of the determination, the estimation timer has not expired, the UE performs a cell change again at step S905 and determines that the performed cell charge is a UE mobility irrelevance cell change.
  • the UE calculates the sum of the number of cell changes related to the mobility state of the UE at step S920. First, the UE calculates the total sum of cell changes and excludes the sum of the number of cell changes corresponding to the determined UE mobility irrelevance cell change (i.e., the sum of the number of cell changes - the number of UE mobility irrelevance cell changes).
  • the UE updates a result of the mobility state estimation of UE updates a result of the estimation based on the number of cell changes related to the mobility state of UE at step S925.
  • the UE updates the existing mobility speed estimation result to a new mobility speed estimation result based on the sum of the number of cell changes related to the mobility state of the UE for an estimation time.
  • the UE may select a scaling factor corresponding to a result of the updated mobility speed estimation (not shown).
  • UE of idle mode may select the scaling factors of Q hyst and T reselection according to Table 1 and Table 2.
  • UE of RRC_connected mode may select the scaling factor of a TTT according to Table 3.
  • the UE scales the cell change parameter as the selected scaling factor (not shown).
  • a new cell change parameter is derived by the scaling of the cell change parameter.
  • UE of idle mode may calculate the new scaling factors of Q hyst and T reselection by scaling the scaling factors of Q hyst and T reselection according to Equation 1 and Equation 2.
  • UE of RRC_connected mode may calculate a new TTT by scaling the TTT according to Equation 3.
  • the calculation of the estimation speed is illustrated as being performed by UE in FIG 9, it may be performed even in a BS that controls a macro cell.
  • FIG. 10 is a flowchart illustrating a method of a BS estimating the mobility state of UE in accordance with an example of the present invention.
  • the BS sends at least one cell change parameter to the UE through an RRC connection reconfiguration message or an SIB at step S1000.
  • the cell change parameter may be transmitted through a different type of a message according to the mode of the UE. For example, if the UE is in RRC_connected mode, the cell change parameter may be transmitted through an RRC connection reconfiguration message. For another example, if the UE is in idle mode, the cell change parameter may be transmitted through a System Information Block. In particular, the cell change parameter may be transmitted through an SIB type3 information message.
  • the cell change parameter received from the BS is a value defined in a corresponding system and may be transmitted by the BS of a macro cell or the BS of a pico cell. Furthermore, the cell change parameter is control information that is used to reduce a cell change failure when the UE performs a cell change from a current cell to another cell.
  • the cell change parameter may be differently defined according to the mode of UE (i.e., idle mode or RRC_connected mode).
  • the cell change parameter may include Q hyst , T reselection , a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , a low-speed determination time, or the density of small cells.
  • the cell change parameter may include a medium-speed reference value Th M and a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of UE , a low-speed determination time, the density of small cells, and a scaling factor.
  • Th M may be 16.
  • the cell change parameter may include a medium-speed reference value Th M and a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of UE , a low-speed determination time, or a scaling factor.
  • the cell change parameter may further include the density of small cells.
  • the scaling factor is a value that is multiplied so that T reselection may be scaled or a value that is added so that Q hyst may be scaled according to the estimation speed of UE.
  • Each of the medium-speed reference value and the high-speed reference value may be an integer value ranging from 1 to M.
  • M may be 16.
  • the cell change parameter may include a TTT, a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , or a low-speed determination time.
  • the cell change parameter may further include the density of small cells.
  • the TTT is a parameter that enables UE to enter a handover preparation stage, such as the start of a measurement report, when a wireless state is maintained for the TTT after the wireless state of a new cell is higher than that of a current cell by a specific reference value or higher.
  • the scaling factor is a value that is multiplied so that a TTT may be scaled according to the estimation speed of UE.
  • the scaling factor may have a different value depending on the level of the speed of UE. If the estimation speed of UE of RRC_connected mode is the high speed, the UE scales a TTT in such as a way as to be reduced so that a handover is performed rapidly. If the estimation speed is the low speed, the UE scales a TTT in such as a way as to be increased.
  • the BS performs a cell change procedure with the UE of RRC_connected mode based on the cell change parameter at step S1005. For example, the BS handovers the UE of RRC_connected mode to another cell.
  • the UE of idle mode itself makes a determination and performs cell reselection irrespective of the BS. Meanwhile, the procedure of S1005 may be omitted because the UE of idle mode performs cell reselection under its determination.
  • a scaling factor value may be applied to the cell change parameter according to the mobility state of UE estimated for the old estimation time. That is, UE of idle mode scales a Q hyst value and a T reselection value as in Equation 1 and Equation 2 using the scaling factor values of Table 1 and Table 2. UE of RRC_connected mode scales a TTT value as in Equation 3 using the scaling factor values of Table 3.
  • FIG. 11 is a block diagram of a BS that controls a cell and UE that communicates with the cell in accordance with an example of the present invention.
  • the UE 1100 includes a receiver 1105, a processor 1110, and a transmitter 1115.
  • the processor 1110 includes a cell change execution unit 1111, a UE mobility irrelevance cell change determination unit 1112, a sum calculation unit 1113, and an estimation result update unit 1114.
  • the receiver 1105 receives at least one cell change parameter from the BS 1150.
  • the cell change parameter is control information that is used to reduce a cell change failure when the UE 1100 performs a cell change from a current cell to another cell.
  • the cell change parameter is a parameter, that is, a basis for estimating the speed of the UE 1100.
  • the cell change parameter may be differently defined according to the mode of UE 1100. For example, if the UE 1100 is idle mode, the cell change parameter may include Q hyst , T reselection , a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , a low-speed determination time, or the density of small cells.
  • the cell change parameter may be transmitted through SIB.
  • the cell change parameter may include a TTT, a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , a low-speed determination time, or the density of small cells.
  • the cell change parameter may be transmitted through RRC connection reconfiguration message.
  • the processor 1110 of the UE 1100 determines whether the final estimation speed of the UE 1100 is the high speed, the medium speed, or the low speed based on the cell change parameter.
  • the processor 1110 may include another components such as a speed estimation unit 1711 of Fig. 17.
  • the processor 1110 may estimate the speed of the UE 1100.
  • the estimation result update unit 1114 of the processor 1110 may perform like the speed estimation unit 1711.
  • the cell change execution unit 1111 performs the cell change of the UE 1100.
  • the UE mobility irrelevance cell change determination unit 1112 determines whether or the cell change of the UE 1100 performed by the cell change execution unit 1111 is a cell change that is not related to the mobility state of the UE 1100.
  • the UE mobility irrelevance cell change determination unit 1112 determines that the performed cell change is a cell change not related to the mobility state of the UE 1100, if the performed cell change is a cell change performed according to a change in the mode of the UE 1100 placed in a cell expansion range.
  • the UE mobility irrelevance cell change determination unit 1112 determines that the performed cell change is a cell change not related to the mobility state of the UE 1100, if the performed cell change is a cell change performed when a difference between the Reference Signal Received Quality (RSRQ) of a source BS, measured by the UE 1100 affected by IDC interference, and the RSRQ of a target BS complies with a predetermined cell change condition.
  • RSRQ Reference Signal Received Quality
  • the UE mobility irrelevance cell change determination unit 1112 determines that the performed cell change is a cell change not related to the mobility state of the UE 1100, if the performed cell change is a cell change for receiving service through a second frequency band when the UE 1100 that receives service from a macro BS through a first frequency band has moved to a Closed Subscriber Group (CSG) cell region to which the UE 1100 does not have a membership.
  • CSG Closed Subscriber Group
  • the UE mobility irrelevance cell change determination unit 1112 determines that the performed cell change is a cell change not related to the mobility state of the UE 1100, if the performed cell change is a cell change for receiving service through a first frequency band after the UE 1100 that receives service from a macro BS through a second frequency band within a CSG cell range to which the UE 1100 does not have a membership moves out of the CSG cell range to which the UE 1100 does not have a membership.
  • the sum calculation unit 1113 calculates the sum of the number of cell change that is related to the mobility state of the UE 1100 for an estimation time. For example, in calculating the sum of the number of cell changes related to the mobility state of the UE 1100 for an estimation time, if the cell change of the UE 1100 is a cell change related to the mobility state of the UE 1100, the UE 1100 calculates the sum of the number of cell changes by increasing a cell change number counter by 1. If the cell change of the UE 1100 is a cell change not related to the mobility state of the UE 1100, the UE 1100 calculates the sum of the number of cell changes by not increasing the cell change number counter. For another example, the UE 1100 may calculate the total sum of cell changes and then calculate the sum of the number of cell changes related to the number of cell changes by excluding the number of times corresponding to cell changes not related to the mobility state of the UE 1100.
  • the estimation result update unit 1114 updates a result of the mobility state estimation based on the sum of the number of cell changes related to the mobility state of the UE 1100 when the estimation timer expires.
  • the estimation result update unit 1114 determines whether the mobility state of the UE 1100 is the high speed, the medium speed, or the low speed based on the cell change parameter.
  • the estimation result update unit 1114 scales at least one cell change parameter according to the mobility state of the UE 1100 estimated for an old estimation time.
  • the estimation result update unit 1114 selects a scaling factor corresponding to a result of the updated mobility speed estimation and scales the cell change parameter as the selected scaling factor.
  • the UE transmitter 1115 sends a signal necessary for a cell change to the BS 1550 based on the updated mobility state measurement result.
  • the BS 1150 include a transmitter 1155, a receiver 1160, and a processor 1170. Furthermore, the processor 1170 includes a cell change control unit 1171 and a cell change parameter generation unit 1172.
  • the cell change parameter generation unit 1172 generates the cell change parameter.
  • the cell change parameter transmitted by the BS 1150 is a value defined in a corresponding system and may be transmitted by the BS of a macro cell or the BS of a pico cell. Furthermore, the cell change parameter is control information that is used to reduce a cell change failure when the UE 1100 performs a cell change from a current cell to another cell.
  • the cell change parameter may be differently defined according to the mode of UE (i.e., idle mode or RRC_connected mode).
  • the cell change parameter may include Q hyst , T reselection , a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , a low-speed determination time, or the density of small cells.
  • the cell change parameter may include a medium-speed reference value Th M and a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of UE , a low-speed determination time, the density of small cells, and a scaling factor.
  • Th M may be 16.
  • the cell change parameter may include a medium-speed reference value Th M and a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of UE , a low-speed determination time, or a scaling factor.
  • the cell change parameter may further include the density of small cells.
  • the scaling factor is a value that is multiplied so that T reselection may be scaled or a value that is added so that Q hyst may be scaled according to the estimation speed of UE.
  • the scaling factor may have a different value according to the level of the speed of UE. If the estimation speed of UE of idle mode is the high speed, the UE scales T reselection and a Q hyst value in such a way as to be reduced so that cell reselection may be performed rapidly. If the estimation speed is the low speed, the UE scales T reselection and a Q hyst value so that they are increased.
  • each of the medium-speed reference value and the high-speed reference value included in the cell change parameter may be an integer value ranging from 1 to M.
  • M may be 16.
  • the cell change parameter may include a TTT, a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , or a low-speed determination time.
  • the cell change parameter may further include the density of small cells.
  • the TTT is a parameter that enables UE to enter a handover preparation stage, such as the start of a measurement report, when a wireless state is maintained for the TTT after the wireless state of a new cell is higher than that of a current cell by a specific reference value or higher.
  • the scaling factor is a value that is multiplied so that a TTT may be scaled according to the estimation speed of UE.
  • the scaling factor may have a different value depending on the level of the speed of UE. If the estimation speed of UE of RRC_connected mode is the high speed, the UE scales a TTT in such as a way as to be reduced so that a handover is performed rapidly. If the estimation speed is the low speed, the UE scales a TTT in such as a way as to be increased.
  • the transmitter 1155 sends at least one cell change parameter to the UE 1100.
  • the cell change parameter may be received through a different type of a message according to the mode of the UE 1100. For example, if the UE 1100 is in RRC_connected mode, the cell change parameter may be transmitted through an RRC connection reconfiguration message. For another example, if the UE 1100 is in idle mode, the cell change parameter may be transmitted through a System Information Block. In particular, the cell change parameter may be transmitted through an SIB type3 information message.
  • the receiver 1160 receives a signal necessary for the cell change from the UE 1100.
  • the cell change control unit 1171 performs a cell change procedure with the UE 1100.
  • a scaling factor value may be applied to the cell change parameter according to the mobility state of UE estimated for the old estimation time. That is, UE 1100 of idle mode scales a Q hyst value and a T reselection value as in Equation 1 and Equation 2 using the scaling factor values of Table 1 and Table 2. UE 1100 of RRC_connected mode scales a TTT value as in Equation 3 using the scaling factor values of Table 3.
  • the cell change control unit 1171 may perform like cell change control unit 1771 in Fig. 17
  • FIG. 12 is a flowchart illustrating a method of estimating the mobility state of UE in accordance with an example of the present invention.
  • a BS sends a message including at least one cell change parameter to the UE at step S1200.
  • the type of message may be different depending on the state of the UE. For example, if the UE is in connected mode, the message may be an RRC connection reconfiguration message. For another example, if the UE is in idle mode, the message may be a System Information Block (SIB).
  • SIB System Information Block
  • the cell change parameter includes a medium-speed reference value Th M , a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of the UE, a low-speed determination time, the density of small cells, and a scaling factor.
  • the cell change parameter includes a medium-speed reference value Th M , a high-speed reference value Th H , a TTT, an estimation time, a low-speed determination time, the density of small cells, and a scaling factor.
  • the UE calculates the number of cell changes N M and N S at step S1205.
  • N M is the number of cell changes per hour between a macro cell and a macro cell
  • N S is the number of cell changes per hour between a macro cell and a small cell and between a small cell and a small cell.
  • the UE updates the N M or N S .
  • the update of the number of cell changes is that the number of cell changes is increased by 1 whenever a cell change is generated.
  • the cell change may mean that UE of RRC_connected mode performs handover to a new macro cell or a new small cell.
  • the cell change may mean that UE of idle mode reselects a new macro cell or a new small cell.
  • the UE increases the number of cell changes N M by 1. If UE has performs a cell change between a macro cell and a small cell or between small cells, the UE increases the number of cell changes N S by 1. Before an estimation time expires, the UE may increase the number of cell changes N M or N S , and when the estimation time expires, the number of cell changes N M or N S is reset to 0.
  • the estimation time of N M may be identical with or different from the estimation time of N S .
  • the estimation time of N S may have a value, such as 30 seconds, 60 seconds, 180 seconds, or 240 seconds.
  • the UE calculates the first estimation speed of the UE based on the number of cell changes N M and calculates a second estimation speed from N S at step S1210.
  • the first estimation speed is an estimation speed that is purely obtained based on the number of cell changes between a macro cell and a macro cell.
  • the second estimation speed is the speed of the UE that is estimated from the number of cell changes between a macro cell and a small cell or the number of cell changes between a small cell and a small cell. Small cells have not been taken into consideration in the first estimation speed, and thus the second estimation speed is necessary because the number of cell changes in a small cell must be taken into consideration in order to calculate an estimation speed more precisely and reliably.
  • the UE may determine that the first estimation speed is the medium speed not the high speed or the low speed. If Th H ⁇ N M , the UE may determine that the first estimation speed is the high speed. If the first estimation speed is not determined to be the high speed or the medium speed for a low-speed determination time, the UE may determine that the first estimation speed is the low speed. A method of calculating the first estimation speed may also be likewise applied to the calculation of the second estimation speed.
  • the UE divides the number of cell changes into the number of cell changes between a macro cell and a macro cell and the number of cell changes between a macro cell and a small cell (including the number of cell changes between a small cell and a small cell) and gathers them for the estimation time.
  • the UE calculates a final estimation speed at step S1215.
  • the final estimation speed is calculated as the high speed, the medium speed, or the low speed based on the first estimation speed and the second estimation speed as in the following table.
  • Table 4 first estimation speed second estimation speed final estimation speed High speed High speed High speed High speed Medium speed High speed or medium speed High speed Low speed High speed or low speed Medium speed High speed High speed or medium speed Medium speed Medium speed Medium speed Low speed Medium speed or low speed Low speed High speed High speed or low speed Low speed Medium speed Medium speed or low speed Low speed Low speed low speed
  • the final estimation speed at the rightmost column is determined by a combination of the first estimation speed and the second estimation speed that are obtained from the number of cell changes that is different depending on the size of a cell. For example, if the first estimation speed generated for a specific time is the high speed and the second estimation speed is the high speed, the final estimation speed is calculated as the high speed because UE may be commonly determined to move at high speed. Meanwhile, if the first estimation speed is the high speed and the second estimation speed is the low speed, the final estimation speed may be the high speed or the low speed. For example, if the second estimation speed is obtained because the density of small cells is low, it is difficult to verify the first estimation speed based on the second estimation speed.
  • the final estimation speed may be the high speed or the low speed.
  • the density of small cells is high, although there is a high probability that UE may perform a cell change to small cells, there is a high probability that the real speed of the UE will be the low speed because the second estimation speed is the low speed. In this case, the UE may be determined to move at the edge of a macro cell at low speed.
  • the final estimation speed may be the high speed or the low speed.
  • the second estimation speed has high reliability because the second estimation speed is high although the probability is low. That is, there is a high probability that the UE will be at the high speed. In this case, it may be determined that the UE is rapidly moving a relatively narrow area.
  • the final estimation speed is calculated as the high speed, the medium speed, or the low speed based on the first estimation speed, the second estimation speed, and the density of small cells as in the following table.
  • ambiguity may be reduced because the density of small cells distributed within a macro cell is used as a calculation factor when it is difficult to calculate the final estimation speed using the first estimation speed and the second estimation speed only.
  • the density of small cells may mean the number of small cells within the macro cell or may mean a coverage ratio of a small cell.
  • the final estimation speed of UE is calculated with consideration taken of that small cells occupy how great area on the average within macro cells to which the UE has moved. That is, the reliability of the second estimation speed may be increased by taking the density of small cells that are occupied within a macro cell into consideration.
  • the first estimation speed is the high speed
  • the second estimation speed is the low speed
  • the density of small cells is high
  • the final estimation speed may be determined to be the low speed, that is, the second estimation speed. This is because there is a high probability that UE will have the low speed because the second estimation speed has been determined to be the low speed even though there is a high probability that the second estimation speed will be high because of the high density of small cells.
  • the final estimation speed may be determined to be the high speed, that is, the second estimation speed. This is because there is a high probability that the second estimation speed will be actually the high low speed because the second estimation speed has been estimated to be the high speed even though there is a high probability that the second estimation speed will be the low speed because of the low density of small cells.
  • the density of small cells as described above, may be used to increase the reliability of the second estimation speed.
  • the density of small cells does not always increase the reliability of the second estimation speed. If the density of small cells is high and the second estimation speed is high, it is difficult to determine why the second estimation speed has been estimated to be high because the reason results from that the density of small cells is high or that UE has actually moved at high speed. Likewise, if the density of small cells is low and the second estimation speed is low, it is difficult to determine why the second estimation speed has been estimated to be low because the reason results from that the density of small cells is low or that UE has actually moved at low speed.
  • Table 5 A difference between Table 4 and Table 5 is that the final estimation speed is adjusted based on the density of small cells. That is, in Table 5, the final estimation speed calculated based on the first and the second estimation speeds is adjusted based on the density of small cells again. Table 5 is only an example in which the final estimation speed is calculated by combining the first estimation speed, the second estimation speed, and the density of small cells, and the final estimation speed may be calculated by other combinations different from Table 5.
  • Information on the density of small cells is included in an SIB or an RRC connection reconfiguration message as a cell change parameter and may be transmitted from a BS to UE. In some embodiments, information on the density of small cells may be directly calculated by UE.
  • the UE selects a scaling factor corresponding to the final estimation speed at step S1220. For example, if the UE is in RRC_connected mode, the UE selects a scaling factor, corresponding to the final estimation speed, from scaling factors for scaling a TTT, that is, a cell change parameter.
  • the scaling factors for scaling the TTT may be 0.25, 0.5, 0.75, and 1.
  • Each of the scaling factors corresponds to the final estimation speed of the high speed, the medium speed, or the low speed.
  • the following table shows an example of the scaling factors of a TTT corresponding to the final estimation speed.
  • the UE selects a scaling factor, corresponding to the final estimation speed, from scaling factors for scaling Q hyst and T reselection , that is, cell change parameters.
  • the scaling factors of Q hyst for scaling Q hyst may include -6 dB, -4 dB, -2 dB, and 0 dB.
  • Each of the scaling factors of Q hyst corresponds to the final estimation speed of the high speed, the medium speed, or the low speed.
  • the following table shows an example of the scaling factors of Q hyst corresponding to the final estimation speed.
  • the following table shows an example of the scaling factors of T reselection corresponding to the final estimation speed.
  • the UE scales the cell change parameter using the scaling factor at step S1225.
  • a new cell change parameter is derived by the scaling of the cell change parameter. For example, if the UE is in RRC_connected mode, a cell change parameter to be scaled is a TTT. For example, if the final estimation speed of the UE is the high speed, the UE selects the scaling factor of a TTT as 0.25 and scales the TTT. The scaling of the TTT is performed by multiplying the TTT by the scaling factor. When an old TTT is multiplied by the scaling factor, a new TTT into which the final estimation speed has been incorporation is obtained.
  • a cell change parameter to be scaled is Q hyst or T reselection .
  • the UE selects the scaling factor of Q hyst as -6 dB and scales Q hyst .
  • the scaling of Q hyst is performed by adding the scaling factor to Q hyst .
  • new Q hyst into which the final estimation speed has been incorporated is obtained.
  • the UE selects the scaling factor of T reselection as 0.25 and scales T reselection .
  • the scaling of T reselection is performed by multiplying T reselection by the scaling factor as in Equation below. When old T reselection is multiplied by the scaling factor, new T reselection into which the final estimation speed has been incorporated is obtained.
  • FIG. 12 shows an example in which the calculation of the final estimation speed is performed by UE, but the calculation of the final estimation speed may be performed in a BS that controls a macro cell.
  • a conversion method between the number of cell changes in which only a macro cell is taken into consideration and the first estimation speed and a conversion method between the number of cell changes in which a small cell is taken into consideration and the second estimation speed are described in detail.
  • the number of cell changes in which only a macro cell is taken into consideration refers to the number of cell changes that is counted when UE performs a cell change from any macro cell to another macro cell.
  • the number of cell changes in which only a small cell is taken into consideration refers to the number of cell changes that is counted when UE performs a cell change from a macro cell to a small cell or performs a cell change from any small cell to another small cell.
  • the diameter of the macro cell is about 1 km. Furthermore, 180 seconds are used as an estimation time. For example, if a first estimation speed calculated based on the number of cell changes in which only a macro cell is taken into consideration is sought to be the high speed, the number of cell changes must exceed 4 times for the 180 seconds. That is, the number of cell changes is 5 times, 6 times, .... In this case, the real speed of UE is faster than 60 km/h.
  • the number of cell changes must exceed 2 times, but must not exceed 4 times for 180 seconds. That is, the number of cell changes is 3 times and 4 times.
  • the real speed of UE is higher than 30 km, but 60 km or lower.
  • the first estimation speed is determined not to be the medium speed or the high speed for 60 seconds. In this case, the real speed of UE is 30 km or lower.
  • the diameter of the small cell is about 20 m. Furthermore, 180 seconds is used as an estimation time. It is to be noted that there is a problem in that the number of cell changes in which only the small cell is taken into consideration is directly converted into a moving distance because an overlapping portion is small between a macro cell and a macro cell, but the small cell is placed within or at the edge of the macro cell.
  • the number of cell changes per second estimation speed has to be individually determined unlike in the conversion method between the number of cell changes in which only a macro cell is taken into consideration and the first estimation speed.
  • the conversion method between the number of cell changes in which only a small cell is taken into consideration and the second estimation speed may be previously agreed between UE and a BS.
  • the BS must transmit a medium-speed reference value and a high-speed reference value for the conversion to the UE as cell change parameters.
  • this conversion may be determined by a service provider so that UE directly perform the conversion.
  • the time that is taken for UE to perform a cell change to another small cell or a macro cell again after the UE has performed a cell change to any small cell hereinafter called a 'small cell stay time'
  • the moving distance of the UE for the small cell stay time have to be taken into consideration.
  • FIG. 13 is a flowchart illustrating a conversion method between the number of cell changes in which only a small cell is taken into consideration and a second estimation speed in accordance with an example of the present invention.
  • the density of small cells is incorporated into conversion between the number of cell changes in which only a small cell is taken into consideration and the second estimation speed. Accordingly, conversion between the number of cell changes and the second estimation speed is adjusted, and thus a high-speed reference value and a medium-speed reference value for a small cell are adjusted.
  • FIG. 13 shows an example in which the conversion method is performed by UE, but the conversion method of FIG. 13 may be performed by BS.
  • UE receives at least one cell change parameter, including information on the density of small cells, from a macro cell at step S1300. This is because a small cell stay time is calculated based on the density of small cells within the macro cell. Accordingly, the UE has to first receive the information on the density of small cells from the macro cell as the cell change parameter.
  • the information on the density of small cells may be received through an RRC connection reconfiguration message if the UE is in RRC_connected mode.
  • the information on the density of small cells may be received through an SIB if the UE is in idle mode.
  • the UE calculates a small cell stay time based on the density of small cells at step S1305. For example, if a radius of a macro cell is 500 m and a radius of a small cell is 10 m, an area of the macro cell is 785,000 m 2 and an area of the small cell is 314 m 2 . If the density of small cells (based on an area) within the macro cell is about 2%, there are about 50 small cells within the macro cell having the radius of 500 m. Accordingly, if the UE moves at a constant speed for an estimation time of 180 seconds, the small cell stay time becomes 3.6 seconds, that is, 2% of 180 seconds in probability. This may be expressed by the following equation below.
  • T stay is the small cell stay time of the UE
  • T measure is an estimation time taken to measure the number of cell changes in which only a small cell is taken into consideration
  • D S is the density of small cells within the macro cell.
  • the 'stay' of the UE that is meant by the small cell stay time T stay does not necessarily mean that the UE moves only within the small cell for the small cell stay time T stay , but means that the UE stays within the small cell while the UE performs a cell change between the macro cell and the small cell.
  • the UE calculates the distance that the UE moves within the small cell while staying at step S1310. If the real speed of the UE is v m/s, the distance S that the UE moves while staying in the small cell for the small cell stay time T stay is calculated by the following equation.
  • the UE adjusts a high-speed reference value and a medium-speed reference value at step S1315.
  • the number of cell changes N S may be obtained as follows based on the distance S obtained according to Equation 5.
  • L is the diameter of the small cell.
  • a new high-speed reference value in which only a small cell is taken into consideration will be 6 times because the UE will alternately move between the small cell and the macro cell.
  • the real speed of the UE is 30 km/h, that is, a medium speed reference value
  • the UE moves 30 m for 3.6 seconds. This movement of 30 m may be seen as a movement only within the small cell.
  • a medium-speed reference value Th M ' in which only a small cell is taken into consideration will be 4 times to 6 times by taking the diameter of the small cell having 20 m into consideration.
  • the UE may convert the levels of the second estimation speed, given as in the following table, into the number of cell changes N S according to Equations 4 to 6.
  • the number of cell changes N S is determined according to Table 9 in relation to the second estimation speed of the UE.
  • the high-speed reference value is 6, and the medium-speed reference value is 3.
  • a correlation between the number of cell changes N S in which only a small cell is taken into consideration and the number of cell changes N M in which only a macro cell is taken into consideration may be estimated. That is, it may be estimated that one increase in the number of cell changes N M corresponds to an increase of several times the number of cell changes N S . For example, assuming that the number of cell changes when a first estimation speed is the high speed is 4 times per 180 seconds and the density of small cells is 2% and the number of cell changes when a second estimation speed is the high speed is 6 times per 180 seconds, it may be seen that one increase in the number of cell changes N M corresponds to an increase of 1.5 times of the number of cell changes N S .
  • the procedure from the step S1305 to the step S1315 may be previously performed before the step S1205 of FIG. 12. That is, if the high-speed reference value and the medium-speed reference value for calculating the second estimation speed is adjusted according to the step S1315, the UE may calculate the number of cell changes N S in which only a small cell is taken into consideration according to the step S1205 and then calculate the second estimation speed according to the step S1210.
  • the medium-speed reference value has been determined to be a first integer value (e.g., 3) between 1 and 16 and the high-speed reference value has been adjusted to be a second integer value (e.g., 6) between 1 and 16 at the steps S1300 to S1315, if the number of cell changes N S calculated at the step S1205 is 5, the second estimation speed becomes the medium speed at the step S1210.
  • a first integer value e.g., 3
  • the high-speed reference value has been adjusted to be a second integer value (e.g., 6) between 1 and 16 at the steps S1300 to S1315
  • a final estimation speed may be calculated according to the following table.
  • the second estimation speed according to the conversion method that has been adjusted by the density of small cells is called an adjusted second estimation speed.
  • the adjusted second estimation speed has higher reliability than the first estimation speed because it is a value determined by taking the density of small cells into consideration. Accordingly, the adjusted second estimation speed is determined as a final estimation speed.
  • the cell change parameter may not include information on the density of small cells.
  • the UE may convert an estimation speed according the sum of the N M and the adjusted N S into the final estimation speed.
  • This illustration is presented in the following table.
  • the method of adjusting N S according to Table 6 corresponds to a correlation between the number of cell change N S in which only a small cell is taken into consideration and the number of cell changes N M in which only a macro cell is taken into consideration. That is, it may be estimated that one increase of N M corresponds to how many increases of N S .
  • N M Ns / 1.5.
  • a new high-speed reference value new Th H and a medium-speed reference value new Th M have to be determined. That is, if N M +adjusted N S exceeds the new high-speed reference value new Th H , a final estimation speed becomes the high speed. If N M +adjusted N S is greater than the new medium-speed reference value new Th M , but is the new high-speed reference value new Th H or lower, a final estimation speed becomes the medium speed. If N M +adjusted N S does not correspond to the high speed or the medium speed, a final estimation speed becomes the low speed.
  • the conversion method of FIG. 13 may be performed by a BS. If the procedure of FIG. 13 is performed by a BS, the BS adjusts a high-speed reference value and a medium-speed reference value regarding a second estimation speed based on Equation 4 to Equation 6, includes the adjusted reference values in cell change parameters, and sends the cell change parameters to UE. Since the adjusted high-speed reference value and the adjusted medium-speed reference value are results into which the density of small cells has been incorporated, the BS may omit information on the density of small cells from the cell change parameters and send the cell change parameters to the UE.
  • FIG. 14 is a flowchart illustrating a method of UE estimating the mobility state of the UE in accordance with an example of the present invention.
  • the UE receives at least one cell change parameter from a macro cell at step S1400.
  • the cell change parameter is basis for estimating the speed of the UE.
  • the UE determines whether the final estimation speed of the UE is the high speed, the medium speed, or the low speed based on the cell change parameter.
  • the cell change parameter may be differently defined depending on the mode of the UE.
  • the cell change parameter includes a medium-speed reference value Th M , a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of the UE, a low-speed determination time, the density of small cells, and a scaling factor.
  • the cell change parameter is included in an SIB and received.
  • the cell change parameter includes a medium-speed reference value Th M , a high-speed reference value Th H , a TTT, an estimation time, a low-speed determination time, the density of small cells, and a scaling factor.
  • the cell change parameter is included in an RRC connection reconfiguration message and received.
  • a common medium-speed reference value Th M and a common high-speed reference value Th H may be used in order to calculate a first estimation speed and a second estimation speed.
  • the macro cell has only to send one medium-speed reference value and one high-speed reference value to the UE.
  • a different medium speed reference value and a different high-speed reference value may be used to calculate the first estimation speed and the second estimation speed.
  • reference values used to convert the first estimation speed may include a first medium-speed reference value Th M and a first high-speed reference value Th H
  • reference values used to convert the second estimation speed may include a second medium-speed reference value Th M ' and a second high-speed reference value Th H '.
  • the macro cell may send all the first medium-speed reference value, the second medium-speed reference value, the first high-speed reference value, and the second high-speed reference value to the UE, or the UE may directly determine the second medium-speed reference value and the second high-speed reference value.
  • a method of the UE directly determining the second medium-speed reference value and the second high-speed reference value may include, for example, the steps S1305 to S1315.
  • the UE calculates the numbers of cell changes N M and N S at step S1405. That is, the UE divides the number of cell changes into the number of cell changes between a macro cell and a macro cell and the number of cell changes between a macro cell and a small cell (including the number of cell changes between a small cell and a small cell) and gathers them for an estimation time.
  • the step S1405 is described in more detail with reference to FIG. 15.
  • FIG. 15 is a flowchart illustrating a method of UE calculating the number of cell changes for an estimation time according to the present invention.
  • the UE performs a cell change based on cell change parameters, such as a TTT, Q hyst , and T reselection at step S1500.
  • the cell change includes i) a cell change from a macro cell to a macro cell ii) a cell change from a macro cell to a small cell, iii) a cell change from a small cell to a small cell, and iv) a cell change from a small cell to a small cell.
  • the cell change is reveal to handover when the UE is in RRC_connected mode, and into cell reselection when the UE is in idle mode.
  • the UE updates the number of cell changes N M or N S at step S1505. For example, if the cell change corresponds to i), the UE increases the number of cell changes N M by 1. If the cell change corresponds to ii), iii), or iv), the UE increases the number of cell changes N S by 1.
  • the UE determines whether an estimation time has expired or not at step S1510. This is because the UE may increase the number of cell changes N M or N S until the estimation time expires and resets the number of cell changes N M or N S to when the estimation time expires.
  • the estimation time of the number of cell changes N M may be identical with or different from the estimation time of the number of cell changes N S .
  • the estimation time of the number of cell changes N S may have a value, such as 30 seconds, 60 seconds, 180 seconds, or 240 seconds.
  • the UE performs a next cell change at step S1500. If, as a result of the determination, the estimation time has expired, the UE performs the step S1410 of FIG. 14.
  • the UE converts the number of cell changes N M into a first estimation speed and converts the number of cell changes N S into a second estimation speed at step S1410. For example, as described with reference to the step S1210, if Th M ⁇ N M ⁇ Th H , the UE may determine that the first estimation speed is the medium speed. If Th H ⁇ N M , the UE may determine that the first estimation speed is the high speed. If the first estimation speed is determined not to be the high speed or the medium speed for a low speed determination time, the UE may determine that the first estimation speed is the low speed. Meanwhile, if Th M ' ⁇ N S ⁇ Th H ', the UE determines that the second estimation speed is the medium speed. If Th H ' ⁇ N S , the UE determines that the second estimation speed is the high speed.
  • the UE calculates a final estimation speed at step S1415.
  • the final estimation speed is calculated as the high speed, the medium speed, or the low speed based on the first estimation speed and the second estimation speed as in the following table.
  • Table 12 first estimation speed second estimation speed final estimation speed High speed High speed High speed High speed Medium speed High speed or medium speed High speed Low speed High speed or low speed Medium speed High speed High speed or medium speed Medium speed Medium speed Medium speed Medium speed Low speed Medium speed or low speed Low speed High speed High speed or low speed Low speed Medium speed Medium speed or low speed Low speed Low speed Low speed Low speed Low speed
  • the final estimation speeds at the rightmost column are determined by combinations of the first estimation speed and the second estimation speed that are obtained from the number of cell changes distinguished depending on the size of a cell.
  • the final estimation speed is calculated as the high speed, the medium speed, or the low speed based on the first estimation speed, the second estimation speed, and the density of small cells as in the following table.
  • the final estimation speed of UE is calculated by taking that small cells within a macro cells to which the UE has moved occupy how many area on the average into consideration.
  • a second medium-speed reference value Th M ' and a second high-speed reference value Th H ' are separately determined by taking the density of small cells into consideration, criteria for conversion between the number of cell changes and the second estimation speed have been adjusted. As a result, the second estimation speed may be adjusted. Accordingly, a final estimation speed may be calculated as in the following table based on the adjusted second estimation speed because the adjusted second estimation speed has higher reliability.
  • UE may convert an estimation speed according to a value obtained by adding N M and adjusted N S as in the following table into a final estimation speed.
  • a method of adjusting N S corresponds to conversion according to Table 6, and it is a correlation between the number of cell changes N S in which only a small cell is taken into consideration and the number of cell changes N M in which only a macro cell is taken into consideration. That is, it may be estimated that one increase of N M corresponds to how many increases of N S .
  • the UE selects a scaling factor corresponding to the final estimation speed at step S1420. For example, if the UE is in RRC_connected mode, the UE selects a scaling factor corresponding to the final estimation speed from scaling factors for scaling a TTT, that is, a cell change parameter.
  • the UE selects a scaling factor corresponding to the final estimation speed from scaling factors for scaling Q hyst and T reselection , that is, cell change parameters.
  • the UE scales the cell change parameter based on the scaling factor at step S1425.
  • a new cell change parameter is derived by the scaling of the cell change parameter. For example, if the UE is in RRC_connected mode, a cell change parameter to be scaled is a TTT. The scaling of the TTT is performed by multiplying the TTT by the scaling factor.
  • a cell change parameter to be scaled is Q hyst or T reselection .
  • the scaling of Q hyst is performed by adding the scaling factor to Q hyst .
  • new Q hyst into which the final estimation speed has been incorporated is obtained.
  • T reselection The scaling of T reselection is performed by multiplying T reselection by the scaling factor.
  • old T reselection is multiplied by the scaling factor, new T reselection into which the final estimation speed has been incorporated is obtained.
  • the UE performs a cell change based on the new cell change parameter at step S1430. For example, if the UE is in RRC_connected mode, the UE performs handover to a new cell. For another example, if the UE is in idle mode, the UE reselect a new cell.
  • FIG. 16 is a flowchart illustrating a method of a BS estimating the mobility state of UE in accordance with an example of the present invention.
  • the BS sends at least one cell change parameter to UE through an RRC connection reconfiguration message or an SIB at step S1600.
  • the message may be different according to the mode of the UE. For example, if the UE is in RRC_connected mode, the message may be an RRC connection reconfiguration message. For another example, if the UE is in idle mode, the message may be a System Information Block.
  • the cell change parameter may be transmitted through an SIB type3 information message.
  • the cell change parameter is a parameter, that is, a basis for estimating the mobility state of UE. The estimation speed of the UE may be determined among the high speed, a medium speed, and a low speed based on the cell change parameter.
  • the cell change parameter may include a medium-speed reference value Th M and a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of UE , a low-speed determination time, the density of small cells, and a scaling factor.
  • the cell change parameter may include a TTT, a scaling factor, a medium-speed reference value Th M and a high-speed reference value Th H , an estimation time taken to estimate the speed of UE , or a low-speed determination time.
  • the BS performs a cell change procedure with the UE based on the cell change parameter at step S1605. For example, if the UE is in RRC_connected mode, a cell handovers the UE to another cell. For another example, if the UE is in idle mode, the cell breaks connection with the UE and a new cell accesses the UE.
  • a scaling factor value may be applied to the cell change parameter according to the mobility state of UE estimated for the old estimation time. That is, UE of idle mode scales a Q hyst value and a T reselection value as in Equation 1 and Equation 2 using the scaling factor values of Table 1 and Table 2. UE of RRC_connected mode scales a TTT value as in Equation 3 using the scaling factor values of Table 3.
  • FIG. 17 is a block diagram of a BS which controls a cell and UE communicating with the cell in accordance with an example of the present invention.
  • the UE 1700 includes a reception unit 1705, a UE processor 1710, and a transmission unit 1720.
  • the UE processor 1710 includes a speed estimation unit 1711 and a cell change control unit 1712.
  • the reception unit 1705 receives at least one cell change parameter from a BS 1750.
  • the cell change parameter is control information used to reduce a cell change failure when the UE performs a cell change from a current cell to another cell.
  • the cell change parameter is a parameter, that is, a basis for estimating the speed of the UE.
  • the speed estimation unit 1711 estimates the speed of the UE.
  • the speed estimation unit 1711 determines whether the final estimation speed of the UE is the high speed, the medium speed, or the low speed based on the cell change parameter.
  • the cell change parameter may be differently defined depending on the mode of the UE.
  • the cell change control unit 1712 may perform cell change by applying parameter changed based on the estimated speed estimated by the speed estimation unit 1711.
  • processor including the speed estimation unit 1711 and the cell change control unit 1712 may, for example, be equal to processor 1110 in Fig. 10, or include all or some of components of the processor 1110 in Fig. 11.
  • the processor 1710 may include all of some components of the cell change execution unit 1111 and perform cell change of UE 1100.
  • the processor 1710 may include all of some components of the UE mobility irrelevance cell change determination unit 1112 and determine whether or the cell change of the UE 1100 performed by the cell change execution unit 1111 is a cell change that is not related to the mobility state of the UE 1100.
  • the processor 1710 may include all of some components of the sum calculation unit 1113 and calculate the sum of the number of cell change that is related to the mobility state of the UE 1100 for an estimation time.
  • the processor 1710 may include all of some components of the estimation result update unit 1114. And the processor 1710 may update a result of the mobility state estimation based on the sum of the number of cell changes related to the mobility state of the UE 1100 when the estimation timer expires, determine whether the mobility state of the UE 1100 is the high speed, the medium speed, or the low speed based on the cell change parameter, scale at least one cell change parameter according to the mobility state of the UE 1100 estimated for an old estimation time, or select a scaling factor corresponding to a result of the updated mobility speed estimation and scales the cell change parameter as the selected scaling factor.
  • the cell change parameter includes at least one of a medium-speed reference value Th M , a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of the UE, a low-speed determination time, the density of small cells, and a scaling factor.
  • the cell change parameter is included in an SIB and received. Accordingly, if the UE is in idle mode, the reception unit 1705 receives the cell change parameter that is transmitted through the SIB.
  • the cell change parameter includes at least one of a medium-speed reference value Th M , a high-speed reference value Th H , a TTT, an estimation time, a low-speed determination time, the density of small cells, and a scaling factor.
  • the reception unit 1705 receives the cell change parameter that is transmitted through an RRC connection reconfiguration message.
  • the speed estimation unit 1711 calculates the numbers of cell changes N M and N S by variably applying the received cell change parameter to the mode of the UE, converts the number of cell changes N M into a first estimation speed, and converts the number of cell changes N S into a second estimation speed.
  • the speed estimation unit 1711 calculates the final estimation speed of the UE based on the converted first estimation speed and the converted second estimation speed.
  • the cell change control unit 1712 determines scaling factors that is suitable for the final estimation speed of the UE calculated by the speed estimation unit 1711.
  • the cell change control unit 1712 scales the cell change parameters, for example, a TTT, Q hyst , and T reselection , using the determined scaling factors.
  • An example of a method of scaling the cell change parameters using the scaling factors includes Equation 1 to Equation 3.
  • the cell change control unit 1712 After the cell change parameters are scaled, the cell change control unit 1712 performs a cell change procedure based on the scaled cell change parameters. To this end, the cell change control unit 1712 generates a signal necessary for the cell change and sends the signal to the UE transmitter 1720.
  • the UE transmitter 1720 may send the signal necessary for the cell change, for example, a handover request message when the UE is in RRC_connected mode, to a BS.
  • the cell change control unit 1712 performs a cell change procedure with the BS.
  • the BS 1750 includes a transmission unit 1755, a reception unit 1760, and a BS processor 1770.
  • the BS processor 1770 includes a cell change control unit 1771 and a cell change parameter generation unit 1772.
  • the transmission unit 1755 sends at least one cell change parameter to UE.
  • the cell change parameter is generated by the cell change parameter generation unit 1772.
  • the cell change parameter generation unit 1772 generates different cell change parameters by taking the mode of UE into consideration. For example, if the UE is in idle mode, the cell change parameter generation unit 1772 generates cell change parameters, including a medium-speed reference value Th M , a high-speed reference value Th H , Q hyst , T reselection , an estimation time taken to estimate the speed of the UE, a low-speed determination time, the density of small cells, and a scaling factor. Accordingly, the transmission unit 1755 may send an SIB, including the cell change parameters, to the UE.
  • the cell change parameter generation unit 1772 If the UE is in RRC_connected mode, the cell change parameter generation unit 1772 generates the cell change parameters, including a medium-speed reference value Th M , a high-speed reference value Th H , a TTT, an estimation time, a low-speed determination time, the density of small cells, and a scaling factor.
  • the transmission unit 1755 sends an RRC connection reconfiguration message, including the cell change parameters, to the UE.
  • the message transmitted by the transmitter 1755 may be different according to the mode of the UE. For example, if the UE is in RRC_connected mode, the message may be an RRC connection reconfiguration message. For another example, if the UE is in idle mode, the message may be a System Information Block.
  • the reception unit 1760 receives a signal necessary for a cell change from the UE 1700.
  • the reception unit 1760 may receive a handover request message from the UE 1700.
  • the cell change control unit 1771 performs a cell change procedure with the UE 1700.
  • a scaling factor value may be applied to the cell change parameter according to the mobility state of UE estimated for the old estimation time. That is, UE of idle mode scales a Q hyst value and a T reselection value as in Equation 1 and Equation 2 using the scaling factor values of Table 1 and Table 2. UE of RRC_connected mode scales a TTT value as in Equation 3 using the scaling factor values of Table 3.
  • the processor 1770 including the cell change control unit 1771 or the cell change parameter generation unit 1772 may be equal to the processor 1171 in Fig. 17 or include the some or all components of the processor 1170 in Fig. 17

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Abstract

La présente invention concerne un procédé et un appareil permettant d'estimer un état de mobilité. La présente invention consiste à recevoir un paramètre de changement de cellule comprenant une valeur de référence permettant d'estimer la vitesse de l'équipement utilisateur, des informations sur le temps, la densité de petites cellules ou un facteur d'échelle à partir de la station de base (BS) ; et à estimer la vitesse de l'équipement utilisateur sur la base du paramètre de changement de cellule et à déterminer si l'état de mobilité de l'équipement utilisateur est une vitesse élevée, une vitesse moyenne ou une vitesse faible.
PCT/KR2012/009210 2011-11-03 2012-11-02 Appareil et procédé permettant d'estimer un état de mobilité WO2013066120A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR10-2011-0113958 2011-11-03
KR1020110113958A KR20130048993A (ko) 2011-11-03 2011-11-03 무선 단말의 이동상태를 추정하는 장치 및 방법
KR10-2011-0114793 2011-11-04
KR1020110114793A KR20130049652A (ko) 2011-11-04 2011-11-04 무선 단말의 이동상태를 추정하는 장치 및 방법

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