KR101661492B1 - Cell deployment in wireless communication based on train control system - Google Patents

Abstract

In the present invention, a cell is arranged between a station and a station, and a greater number of cells are arranged so that a cell overlapping interval is widened in a high-speed section in accordance with a train speed pattern, thereby lowering the probability of departing from a cell range being serviced, (W) so that the stationary train is not placed in the overlapping area of the cells in order to prevent the ping pong phenomenon occurring when the train stops, and the frequency reuse factor is changed according to the distance between the railroad track or the RRH The present invention provides an arrangement of a base station apparatus applicable to an adjustable wireless communication railroad environment.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a base station apparatus,

More particularly, the present invention relates to an arrangement structure of a base station apparatus, and more particularly, to a radio base station apparatus and a radio base station apparatus, which utilize a train speed pattern between a station and a station and adjust a frequency reuse factor according to a cell spacing, And more particularly, to an arrangement structure of a base station apparatus applied to a wireless communication railroad environment providing a wireless communication environment with high reliability and cell building efficiency.

A conventional communication base station includes a digital signal processing unit and a radio signal processing unit (hereinafter referred to as 'DU') together in one physical system (Remote Radio Head, hereinafter referred to as 'RRH').

The RRH is a base station equipment that makes the base station smaller and lighter than the existing system and facilitates installation and operation in various environments as a next generation mobile communication system.

In mobile communication, a multiple access technique is used to accommodate a plurality of users in one frequency band. However, even if multiple accesses are used, when a certain amount of users access at the same time, channel saturation occurs and normal service becomes difficult.

Therefore, DU, which plays a role of controller and controller in a repeater and a base station by attaching multiple RRHs, is a kind of base station equipment that transmits digital information received from RRH, a frequency transmitting and receiving equipment, to a wired communication network. (CA) or frequency reuse between base stations (DU), thereby enabling the use of mobile communication services in the base station boundary region.

Here, frequency reuse refers to a technique of constructing a communication channel by reusing the same frequency at a constant interval in order to improve spectral efficiency of the frequency. However, if the same frequency is reused in another base station that is separated by a certain distance from the frequency used by a certain base station, interference between adjacent base stations can be effectively avoided, thereby increasing the reliability of communication.

The base station including the high-power linear amplifier is installed on the ground, and the transmission signal output from the base station is transmitted to the tower or the service antenna on the pole by using the feeder line.

The transmission power of a base station means a service coverage or coverage, in particular, a cell coverage that a base station can provide service. The maximum amount of money that can be accommodated in one cell coverage (hereinafter referred to as 'cell') is constant.

Therefore, if the radius of the cell is reduced by half, the area is reduced to 1/4. Therefore, when the cell size is reduced by half, four times as many cells are included in the same area. On the assumption that the distribution of communication users per area is uniform, The amount of money will also increase fourfold. In this case, the size of cells in a place with a large amount of money is reduced and the size of a cell in a place with a small amount of money is wide. However, the cell in the present invention will be described with an electron wavelength having the same intensity and region.

The cell becomes a circular shape centering on the base station on the plane. It is actually a polygonal (usually hexagonal) shape according to the divisional adjustment according to the electric field intensity with the adjacent cell.

The conventional communication base station has to install the base station including all the processing units in the cell, so that the cost of the cell design and the installation cost are rapidly increased. Particularly, in a railway communication environment, unlike a general commercial network, a movement pattern of a car-mounted terminal and a portable terminal mounted on a railway are fixed, and a pattern of a speed is also regular. Therefore, it is necessary to consider a cell arrangement and a base station device by utilizing such characteristics.

In addition, the railroad track is inevitably varied in radius due to geographical influence, and the interval between the cells is narrowed in order to improve the QoS of the radio communication in the railroad track. As a result, inter-cell interference occurs, so cell placement must be performed considering the influence of the communication network.

In addition, problems such as a ping pong phenomenon and a coverage hole in a traveling section due to a superimposed section in the vicinity of a railroad station may occur, resulting in an abnormal phenomenon of train control. Therefore, something to do.

In order to improve this, there is a method of connecting a plurality of DUs and a plurality of RRHs to form a cell, thereby reducing a ping pong phenomenon and a coverage hole. However, Installation costs and power consumption can cause problems.

Accordingly, in order to secure stable cell coverage and ensure efficient QoS (Quality of Service) in a railway wireless communication environment, a method of satisfying both cost reduction and performance stabilization at a small number of base stations is being sought.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to arrange a cell between a station and a station and to arrange a larger number of cells in a high- To reduce the probability of out of range of the cell and prevent the ping pong phenomenon that occurs when the train stops at the periphery of the station, set the appropriate position offset (W) so that the stationary train is not placed in the overlapping area of the cells And an object of the present invention is to provide an arrangement structure of a base station apparatus applicable to a wireless communication railroad environment in which a frequency reuse factor can be adjusted according to a radius of a railroad track.

According to another aspect of the present invention, there is provided an arrangement structure of a base transceiver station applied to a wireless communication railroad environment, the arrangement structure of a base transceiver station in which cells are equally spaced between a station and a station, In order to reduce the probability of the train going out of the range of the service cell when the train passes through the high speed section in accordance with the train speed pattern in the order of high speed, medium speed and low speed, a larger number of cells are arranged in the high speed section, Is widened.

The cells are arranged in a number equal to the number of cells arranged at even intervals between the inverse and inverse of the cells. In the low-speed section, the overlapping sections of the cells are arranged in a small number so that the overlapping sections are narrowed. And is arranged differentially in number.

In order to prevent the ping pong phenomenon occurring when the train stops at the center of the overlapping section of the cell in the arrangement structure of the base station apparatus in which cells are arranged at even intervals around the reverse, (W) is placed at the cell position so that the stopped train is not placed in the overlapping period of the cells.

In addition, in the arrangement structure of the base station apparatus in which the radius of the railroad track is varied (R) and the RRH is arranged at a constant distance (L) along the railroad track, the linear distance between two adjacent RRHs (E-UTRA Absolute Radio Frequency Channel Number) or UARFCN (UTRA Absolute Radio Frequency Channel Number) is cyclically allocated to the RRH so as to prevent relative interference between RRHs And the reuse factor is effectively controlled.

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According to the arrangement structure of the base station apparatus applied to the wireless communication railroad environment of the present invention, the probability of departing from the range of the cell being serviced when passing through the high speed section is lowered, and the probability that the train is stopped at the center of the overlapping period of the cell It is possible to prevent a ping pong phenomenon and to prevent the relative interference between RRHs from increasing even if the radius of the railroad track becomes smaller and the linear distance between two adjacent RRHs becomes smaller.

FIG. 1 is a schematic diagram of an overall configuration of a cell arrangement structure optimized for a speed pattern of a train according to an embodiment of the present invention, wherein (a) is a table showing a speed pattern of a train between reverse and reverse, (b) (C) is a schematic diagram showing a cell range according to the present invention according to a speed pattern of a train.
FIG. 2 is a schematic diagram of the overall configuration of the cell arrangement structure in the vicinity of the station according to the embodiment of the present invention, in which (a) is a table showing the position opposite to the speed pattern of the train, (b) (C) is a schematic view showing an offset in a cell position according to the present invention.
FIG. 3 is a schematic diagram of the overall configuration of a cell arrangement structure in a section where the radius of a railway varies according to an embodiment of the present invention, in which (a) is a schematic view showing a railway line in a straight section, A schematic.
FIG. 4 is a schematic view showing the curve section of FIG. 3 (b) in a straight line shape and cyclically assigning a frequency using the adaptive frequency reuse factor of the present invention. FIG.
FIG. 5 is a schematic view showing how a plurality of RRHs close to a train position are allocated to a plurality of DUs according to an embodiment of the present invention; FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

In the railway wireless communication environment, unlike ordinary commercial networks, the movement patterns of the on-board terminals and the portable terminals mounted on the railway are fixed, and the speed pattern is also regular. Therefore, it is necessary to consider the cell arrangement and the base station apparatus by utilizing such characteristics.

That is, in one embodiment, as shown in FIG. 1 (a), the train speed pattern between the station and the station generally proceeds in the order of low speed, medium speed, high speed, medium speed and low speed. However, if cells are arranged at equal intervals as shown in FIG. 1 (b), the probability of departing from the range of the cell being serviced in the high-speed section becomes relatively high.

Accordingly, as shown in FIG. 1 (c), the number of cells used in FIG. 1 (b) is equal to or greater than the number of cells used, It is possible to solve this problem.

The ping pong phenomenon according to the overlapping region near the railroad station and the coverage hole in the high speed traveling region may cause the anomaly of the train control so that the cell arrangement should be taken into consideration .

That is, as another example, as shown in Fig. 2 (a), the train speed pattern between the station and the station is regular, and the speed of the train in the reverse direction in general should be regarded as zero. However, as shown in FIG. 2 (b), if the train is positioned in the middle of the overlapping region of the cell, the possibility of ping pong according to the overlapping region is relatively increased.

Accordingly, the ping pong phenomenon can be eliminated by placing an offset W at the cell position shown in FIG. 1 (b) so that the trains stopped in the opposite direction are positioned at the center of the cell as shown in FIG. 2 (c). Likewise, it is possible to prevent the ping-pong phenomenon due to cell overlapping at the stationary stop by placing an offset W in the cell position shown in Fig. 1 (c).

Since the radius of the railroad track is inevitably inevitably changed due to the geographical influence of the railroad track, the interference due to the overlapping section is inevitably generated. Therefore, the cell layout should be performed considering the influence of the communication network.

That is, as another embodiment, as shown in FIG. 3 (a), the RRHs arranged in the railway are arranged at a constant distance L. In this case, if the railway is straight, the radius (R) of the railway can be regarded as infinity.

However, as shown in FIG. 3 (b), the actual straight line distance d between the adjacent RRHs arranged at a predetermined distance L along the railroad due to the geographical influence of the railroad track is affected by the radius, It is necessary to make the distance L smaller.

In this case, as the linear distance d between the adjacent RRHs becomes smaller, the relative interference between the two RRHs may increase due to an increase in the shadowing gain of the adjacent RRHs. Therefore, by adjusting the frequency reuse factor, The interference between the RRHs can be effectively mitigated. Particularly, as the cells are differentially arranged according to the speed pattern shown in FIG. 1 (c), the linear distance d between the RRHs arranged along the railway is positioned at the center of the cell, Which may increase the inter-cell interference, so it is desirable to alleviate the interference by greatly adjusting the frequency reuse factor.

FIG. 4 is a diagram illustrating a railway environment system in which the railway line shown in FIG. 3 (b) is displayed in a straight line in an easily recognizable manner. The frequency reuse concept is applied to EARFCN (in case of 4G LTE) or UARFCN (in case of 3G) It is possible to effectively reduce the interference between adjacent RRHs by assigning them to cyclic RRHs.

That is, a carrier frequency corresponding to # 1 of EARFCN or UARFCN is assigned to RRH # 1, RRH # (Z + 1) and RRH # (2Z + 1) It is possible to alleviate interference between adjacent RRHs by assigning a carrier frequency corresponding to # 2 of EARFCN or UARFCN to RRH # (Z + 2) and RRH # (2Z + 2).

In this case, the number Z of frequencies to be reused can be differently different depending on the radius of the railway, and can be used differently according to the interval between the base stations. Specifically, as the radius of the railway decreases, or as the distance between the base stations decreases, the interference between the base stations increases relatively. Therefore, by using Z relatively large, interference can be effectively avoided.

In a railway wireless communication environment, a cell coverage and a railway dedicated wireless network with a small number of base stations form a high-quality signal environment to provide a high quality of service (QoS) level service, There is a plan to make it possible.

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The embodiment of the method of arranging the base station apparatus applied to the wireless communication railroad environment of the present invention described above is merely an example and those skilled in the art will appreciate that various modifications and equivalent It will be appreciated that other embodiments are possible. Therefore, it is to be understood that the present invention is not limited to the above-described embodiments. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims. It is also to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

10: Position information detector 20: DU scheduler

Claims (5)

In an arrangement of a base station apparatus in which a cell is arranged between a station and a station,
In order to lower the probability that the cell will be out of the range of the service cell when the train passes through the high speed zone, the cell may be set to a low speed zone, a low speed zone, a high speed zone, The number of the overlapping sections is narrowed so that the overlapping sections are narrowed. In the high speed section,
And the number of cells is equal to the number of cells disposed between the stations and the stations.
delete The method according to claim 1,
In order to prevent a ping pong phenomenon occurring when a train stops at an overlapping section of a cell arranged in the vicinity of a low speed section, W) of the base station apparatus to be arranged in a wireless communication railroad environment. delete delete

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