KR20150044003A - Method and apparatus for estimating moving speed of mobile terminal in mobile wireless communication system) - Google Patents

Abstract

The present invention relates to a method and an apparatus for estimating the moving speed of a terminal in a mobile wireless communications system. According to the present invention, the terminal performs the following procedures: determining the type of a handover by using a serving cell and a target cell participating in the handover whenever a handover is conducted during a speed estimation updating period; calculating the value of a speed estimation counter corresponding to the type of the handover based on an increment of the speed estimation counter; and estimating a moving speed of the terminal by using the value of the speed estimation counter calculated during the speed estimation updating period.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for estimating a moving speed of a mobile station in a mobile wireless communication system,

The present invention relates to a method and an apparatus for estimating a moving speed of a mobile station in a mobile wireless communication system, and more particularly, to a method of efficiently estimating a moving speed of a mobile station in a mobile communication system, .

A mobile wireless communication system is a next generation communication system that supports mobility in a wireless data communication system using a fixed access point. Various standards have been proposed for a mobile wireless communication system. In particular, LTE (Long Term Evolution) and LTE- (Long Term Evolution), which provide a high-speed packet service based on Orthogonal Frequency Division Multiplexing (hereinafter referred to as OFDM) Advanced standards.

In a mobile communication system, even when a mobile station moves from a cell managed by one base station to another cell managed by another base station, mobility must be guaranteed to provide a data communication service that is not disconnected.

Meanwhile, standardization organizations such as 3GPP and IEEE 802.16 are discussing how to utilize small-sized base stations to efficiently accommodate the congested wireless traffic. A small base station is a base station that manages a narrow service area as compared with a macro base station. The small base station performs the role of sharing the load of the macro base station and improving the communication quality in the area where the coverage of the macro base station is insufficient. In order to reduce the communication cost, And is densely installed.

In the prior art for estimating the mobile speed of the mobile station in the mobile wireless communication system, the number of times of handover (i.e., cell change) for a specific time is used as a main factor, Medium, and Low speeds.

1 shows an example of a moving speed estimation method of a terminal using a conventional technique in a multi-tier network in which a network composed of only macro cells and a small cell and a macro cell coexist.

As shown in FIG. 1, although the mobile terminal moves the same distance at the same speed, two handovers occur in FIG. 1 (a) composed of macro cells A, B and C, 1 (b) where macro cells A, B, and C coexist, four handovers occur. In this case, when only the number of handover times of the terminal is compared for a specific time, it can be mistakenly estimated that the terminal shown in FIG. 1 (a) is moving slower than the terminal shown in FIG. 1 (b). Therefore, the prior art that simply estimates the mobile speed of the mobile station by the number of handovers is suitable for a wireless communication system in which the size of a cell controlled by one base station is constant, but the size of cells controlled by each base station varies or varies In a multi-layer network, there is a problem that errors are likely to occur in estimating the moving speed of the terminal. There is also a problem that there is a high possibility that an error occurs in the setting of the event start timing in the handover control of the terminal.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for estimating a moving speed of a mobile station in a mobile radio communication system capable of efficiently estimating a moving speed of a mobile station in a multi- And an apparatus.

According to an embodiment of the present invention, a method is provided for a mobile station to estimate a moving speed in a mobile wireless communication system. A method for estimating a moving speed of a UE includes receiving a plurality of threshold values according to a speed estimation update period and a moving speed from a base station, and generating a serving cell and a target cell participating in the handover each time a handover occurs during the speed estimation update period Calculating a value of the speed estimation counter based on an increment value of a speed estimation counter corresponding to the type of the handover determined; Estimating a moving speed of the mobile station using a value of the estimation counter and the plurality of threshold values, wherein the increment value of the rate estimation counter has a different value depending on the type of the handover.

According to the embodiment of the present invention, not only a single network composed only of a macro base station but also a multi-layer mobile wireless communication network in which the size of a cell controlled by a base station varies or is fluidly changed, It is possible to estimate the speed, thereby providing seamless service to the mobile terminal.

1 is a diagram illustrating the number of handover times of a terminal in a multi-tier network in which a macro base station and a macro base station coexist.
2 is a diagram schematically illustrating a mobile wireless communication system according to an embodiment of the present invention.
3 is a diagram for explaining a method of updating a speed estimation counter according to an embodiment of the present invention.
4 is a flowchart illustrating a method of transmitting information of a base station according to an embodiment of the present invention.
5 is a flowchart illustrating a method of estimating a moving speed of a terminal according to an embodiment of the present invention.
6 is a diagram illustrating an apparatus for estimating a moving speed of a terminal according to an embodiment of the present invention.
7 is a flowchart illustrating a method of transmitting an increment value of a rate estimation counter in a base station according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

Throughout the specification, a terminal may be referred to as a user equipment (UE), a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS) a high reliability mobile station (HR-MS), a subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT) , AMS, HR-MS, SS, PSS, AT, and the like.

Also, a base station (BS) includes a node B, an evolved node B, an advanced base station (ABS), a high reliability base station (HR-BS) ENB, BS, ABS, HR-BS, etc.), an access point (AP), a radio access station (RAS), a base transceiver station AP, RAS, BTS, and the like.

A method and apparatus for estimating a moving speed of a mobile station in a mobile communication system according to an embodiment of the present invention will now be described in detail with reference to the drawings.

2 is a diagram schematically illustrating a mobile wireless communication system according to an embodiment of the present invention. In FIG. 2, an E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) is illustrated as a mobile radio communication system for convenience.

Referring to FIG. 2, a mobile wireless communication system includes user equipment 110, 120, and 130, evolved nodes B 210 and 220, and an evolved packet core (EPC) 300.

The base stations 210, 220 and 230 perform control of the terminals 110, 120 and 130 or provide data services. The base stations 210, 220 and 230 are installed / installed in various forms such as a macro cell, a picocell, Can be operated. 2, the base stations 210 and 220 manage the macro cells 21 and 22, and the base station 230 manages the small cells 23 having a smaller cell coverage than the macro cells 21 and 22. The base stations 210 and 220 that manage the macro cells 21 and 22 are referred to as a macro base station and the base station 230 that manages the small cells 23 is referred to as a small base station.

The base stations 210, 220 and 230 can exchange control information through the X2 interface.

The EPC 300 has information on the connection information of the terminals 110, 120 and 130 and the capabilities of the terminals 110, 120 and 130 and performs mobility management and gateway functions of the terminals 110, 120 and 130 do.

The terminals 110, 120, and 130 access the base stations 210, 220, and 230 as end points of a wireless channel and transmit and receive data.

In the prior art for estimating the moving speed of the UEs 110, 120 and 130, the number of handovers performed by the UEs 110, 120 and 130 for a specific time is used as a main parameter, Cell, i.e., a macro-cell. However, in a network in which the macro cells 21 and 22 and the small cells 23 are scattered as shown in FIG. 2, when calculating the number of cell changes only considering the macro cells 21 and 22, reliability of the cell change number Can fall.

In an embodiment of the present invention, a new rate estimation counter is defined to solve this problem. The rate estimation counter is updated each time a handover occurs and a different value is applied to the update unit depending on the cell size of the serving cell and the target cell participating in the handover. That is, the increment value of the speed estimation counter is increased differently depending on the cell size of the serving cell and the target cell participating in the handover. In the case of a mobile communication system including only macrocells, since the cell size of the serving cell and the target cell is the same, the speed estimation counter increases by one for each handover, and therefore becomes equal to the number of handovers used in the prior art.

3 is a diagram for explaining a method of updating a speed estimation counter according to an embodiment of the present invention.

3, it is assumed that the cell size ratio of the macro cells 31 and 32 and the small cells 33 and 34 is 3 to 1, and the 1 st, 2 nd and 3 rd handovers (①, ②, and ③) And the fourth handover (4) indicates the result of the handover of the terminal 100 directly to the macro cell 22 without passing through the small cells 33 and 34. [

As shown in FIG. 3, the UE 110 performs handover as it moves from one cell to another, and the distance traveled until the handover occurs coincides with the ratio of cell sizes managed by the BSs . Accordingly, the first handover, that is, the distance traveled by the terminal 100 during the time when the handover (1) to the small cell 33 occurs in the macro cell 31 and the second handover, that is, The ratio of the distance traveled by the terminal 100 during the handover (2) to the small cell 34 is 2 to 1 depending on the cell size ratio, and the fourth handover, that is, the macrocell 31 (2) from the small cell 34 to the macro cell 32 during the handover () of the macro cell 32 to the macro cell 32, The ratio of the distance traveled by the terminal 100 is 3 to 1 depending on the ratio of the cell size.

The unit of the rate estimation counter, which is increased each time a handover occurs, can be defined as shown in Table 1 according to the ratio of the cell size.

Handover type Increment value of speed estimation counter Handover from macro cell to macro cell 3 Handover from macro cell to small cell 2 Handover from small cell to macro cell One Handover from small cell to small cell One

The increase value of the rate estimation counter according to the cell size ratio is calculated by using the cell size information included in the neighbor base station information transmitted by the base station 200, As shown in FIG. At this time, the cell size information of the neighbor base station transmitted by the base station 200 includes information on the cell type (macro cell, picocell, micro cell, etc.) of the neighbor base station, transmission power of the neighbor base station, Can be directly or indirectly inferred.

In the case of handover from the macrocell 31 to the small cell 33, unlike the other handover, the reliability of the increment value of the speed estimation counter may be lowered depending on the position of the small cell 33 in the macrocell 31 have. 3, when the small cell 33 is located at the center of the macro cell 31, when there is no handover from the macro cell 31 to the small cell 33 and when there is no small cell 33, ) To the small cell 34 becomes more similar to the ratio of the distance traveled by the terminal 100 that the other value is used. However, this error can be canceled by repeatedly increasing the movement speed counter for a specific time in an environment in which the small cells 33 and 34 are uniformly distributed in the macro cells 31 and 32.

When the small cells 33 and 34 are densely distributed at specific positions in the macro cells 31 and 32 or in order to more accurately estimate the moving speed of the UE 100, As shown in FIG. The location information of the neighbor base station may include a macro base station identifier to which the neighboring small base station belongs, and a position (center, middle, edge) in the macro cell of the adjacent small base station. The MS 100 may subdivide the handover from the macro cell to the small cell that is currently generated through the neighbor base station information provided from the base station into various types of handover according to the position of the small base station managing the small cell, The reliability of the increment value of the speed estimation counter can be increased by increasing the speed estimation counter to a different value for each type of handover.

4 is a flowchart illustrating a method of transmitting information of a base station according to an embodiment of the present invention. In FIG. 4, reference numerals for the terminal 110 and the base station 210 are shown based on the system of FIG. 1, and only one terminal 110 and one base station 210 are shown.

4, the BS 210 sets system information necessary for estimating the moving speed of the AT 110 (S410), and broadcasts the system information to the AT 110 (S420) . The broadcasted system information may include a moving speed updating period indicating the updating period of the moving speed estimation and a threshold value for each speed for estimating the moving speed.

The base station 210 that has transmitted the system information sets neighbor base station information necessary for determining the increment value of the speed estimation counter at step S430 and broadcasts the neighbor base station information to the terminal 110 at step S440. The neighbor base station information includes the cell size information of the neighbor base station. If the adjacent base station is not a macro base station but a small base station, the neighbor base station information may further include location information of the small base station.

Meanwhile, the system information transmitted by the base station 210 may further include an increment value of the speed estimation counter according to the handover type. If the system information includes the increment value of the speed estimation counter according to the type of handover, the terminal 110 does not directly calculate the increase value of the speed estimation counter according to the type of handover, Lt; RTI ID = 0.0 > counter < / RTI >

In this embodiment, the system information transmission and the neighbor base station information transmission occur sequentially. However, depending on the system, two setting and transmission operations may occur simultaneously or may occur in different orders. System information transmission and neighbor base station information transmission occur periodically and may occur periodically from the moment the base station 210 operates normally regardless of whether the terminal 110 is connected or not.

Upon receiving the neighbor base station information, the terminal 110 increments the rate estimation counter by an increment value of the rate estimation counter corresponding to the handover type, using the neighbor base station information each time a handover occurs.

The terminal 110 increases the speed estimation counter by the above-described method each time a handover occurs during the received moving speed updating period. When the moving speed updating period ends, the terminal 110 compares the value of the speed estimation counter with the received speed- And estimates the moving speed of the terminal 110.

5 is a flowchart illustrating a method of estimating a moving speed of a terminal according to an embodiment of the present invention.

Referring to FIG. 5, the terminal 110 sets a speed estimation update timer to a value of a speed estimation update period received from the base station 210, and sets a value of a speed estimation counter to 0 (S502).

When a handover occurs (S504), the UE 110 determines a handover type according to the type of the serving cell and the target cell (S506).

The terminal 110 determines the increment value of the speed estimation counter according to the handover type and increments the speed estimation counter by the increment value of the determined speed estimation counter (S508). At this time, the rate estimation counter increment value according to the handover type can be directly calculated by the terminal using the neighbor base station information received from the base station 210, or received from the base station 210.

The terminal 110 repeats steps S504 to S508 until the speed estimation update timer ends.

The terminal 110 compares the current speed estimation counter value with the threshold value for each speed received from the base station 210 to estimate the current speed of movement, when the speed estimation update timer ends (S510). Specifically, if the terminal 110 is smaller than the medium speed threshold value among the speed estimation counter value and the speed-based threshold value (S512), the terminal 110 can estimate the current moving speed at a low speed (S514). If the value of the speed estimation counter is higher than the high speed threshold value in step S516, the terminal 110 can estimate the current moving speed at a high speed in step S518. At this time, the high speed threshold value may be set to be larger than the medium speed threshold value. If the speed estimation counter is greater than the medium speed threshold and smaller than the high speed threshold, the terminal 110 can estimate the current moving speed at medium speed (S520).

When the moving speed estimation is completed in this way, the terminal 11 sets the speed estimation update timer to the speed estimation update period value, resets the speed estimation counter to 0 (S522), and repeats the series of operations (S502- S520), and estimates the moving speed of the terminal 100. FIG.

6 is a diagram illustrating an apparatus for estimating a moving speed of a terminal according to an embodiment of the present invention.

6, the moving speed estimation apparatus 600 of the AT 100 includes a receiving unit 610, a transmitting unit 620, a counter value calculating unit 630, and a speed estimating unit 640.

The receiving unit 610 receives system information and neighboring base station information from the base station 210. As described above, the system information may include a moving speed update period and a high and medium speed threshold. The system information may further include an increment value of the speed estimation counter according to the handover type. The neighbor base station information may include cell information of a neighboring base station for determining a cell size of a serving cell and a target cell. If the neighbor base station is a small base station, the neighbor base station information may further include position information of the small base station.

The transmission unit 620 can transmit the estimated moving speed information of the terminal 100 to the base station.

The counter value calculator 630 sets the speed estimation update period timer to the value of the speed estimation update period received from the base station 210 and sets the value of the speed estimation counter to zero. The counter value calculation unit 630 increases the speed estimation counter by an increment value of the speed estimation counter according to the type of handover each time a handover occurs until the speed estimation update timer expires. When a handover occurs, the counter value calculator 630 determines the handover type according to the type of the serving cell and the target cell, and determines the handover type based on the cell information included in the neighbor base station information received from the base station 210 The increment value of the speed estimation counter according to the over type can be calculated. Alternatively, when the system information includes the increment value of the speed estimation counter according to the type of the handover, the counter value calculation unit 630 calculates the increment value of the speed estimation counter according to the type of the handover from the base station 210 The increment value of the received speed estimation counter can be used.

The counter value calculation unit 630 transfers the calculated value of the speed estimation counter to the speed estimation unit 640 until the speed estimation update timer expires. Then, the counter value calculation unit 630 sets the speed estimation update timer to the speed estimation update period value, resets the speed estimation counter to zero, and repeats a series of operations.

The speed estimating unit 640 compares the value of the speed estimating counter calculated by the counter value calculating unit 630 with the high and medium speed thresholds to estimate the moving speed of the terminal 100. [

According to another embodiment of the present invention, the base station 200 calculates and determines a value required for estimating the moving speed of the mobile station 100, transmits the calculated value to the mobile station 100, May be used.

7 is a flowchart illustrating a method of transmitting an increment value of a rate estimation counter in a base station according to another embodiment of the present invention.

7, the BS 210 performs handover from a macro cell to a small cell using various handover types using the previous handover history of the MS 110, uplink signal quality, location information of a small base station, and the like And the base station 210 may determine the increment value of the rate estimation counter appropriate for each handover type.

The base station 210 determines handover of the UE 110 based on signal strength information received from the UE 110 (S710).

The base station 210 determines the increment value of the rate estimation counter corresponding to the type of handover determined (S720).

In step S730, the BS 210 determines that handover is required, and transmits the handover command message to the UE 110 in step S730.

Upon receiving the handover command message, the UE 110 performs a handover (S740), and increments the rate estimation counter by an increment value of the rate estimation counter included in the received handover command message (S750).

In this way, the terminal 110 can calculate the value of the speed estimation counter until the speed estimation update timer expires.

Meanwhile, in order to reduce the load of the macro base station, the macro base station can instruct to hand over some of the mobile stations to the small base station regardless of movement of the mobile stations. In this case, the macro base station may further include an indicator in the handover command message that requests not to increase the speed estimation counter, thereby preventing the reliability of the speed estimation counter from being lowered.

If the handover is not caused by the actual movement, the macro base station instructs the macro base station not to increase the speed estimation counter. In this case, when the macro base station estimates the moving speed of the terminal 110, Can be prevented.

At least some functions of the method and apparatus for estimating the moving speed of a terminal according to the above-described embodiments of the present invention can be realized by hardware or software combined with hardware. For example, a processor implemented by a central processing unit (CPU) or other chipset, a microprocessor, or the like may be used as the function of the counter value calculator 630 and the speed estimator 640 of the moving speed estimating apparatus 600 And a transceiver may perform the functions of the receiving unit 610 and the transmitting unit 620 of the moving speed estimating apparatus 600. [

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, Such an embodiment can be readily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (1)

A method for estimating a moving speed of a mobile station in a mobile radio communication system,
Receiving a plurality of thresholds according to a speed estimation update period and a movement speed from a base station,
Determining a type of the handover using a serving cell and a target cell participating in the handover each time a handover occurs during the speed estimation update period;
Calculating a value of the speed estimation counter based on an increment value of the speed estimation counter corresponding to the type of the handover determined; and
Estimating a moving speed of the terminal using the value of the speed estimation counter calculated during the speed estimation update period and the plurality of thresholds
/ RTI >
Wherein the increment value of the speed estimation counter has a different value according to the type of the handover.

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