KR100753220B1 - Handover supporting apparatus for wibro system and the method thereof - Google Patents

Abstract

The present invention relates to an apparatus and a method for supporting handover in a WiBro system. The apparatus for supporting a handover in a WiBro system according to the present invention includes: a list providing unit for providing a neighbor list including neighbor base station information to a terminal; A load determining unit periodically checking a load ratio of a frequency band in service to the terminal to determine whether the load rate is higher than a set value; And a load list of neighboring base station information serving a serviced frequency band to the terminal when the load ratio of the frequency band in service to the terminal is lower than a set value. If it is determined that the load ratio is higher than the set value, the control unit for controlling to provide to the terminal including the neighbor base station information that serves the other frequency band in the neighbor list; It includes. Accordingly, the buffering time caused by the frequent scanning of neighboring base stations serving other frequency bands can be minimized.

WiBro, Handover, Naver List, Buffering

Description

HANDOVER SUPPORTING APPARATUS FOR WIBRO SYSTEM AND THE METHOD THEREOF

1 is a view for explaining a handover in a typical WiBro system.

2 is a view for explaining a base station including a handover support apparatus according to an embodiment of the present invention.

3 is a view for explaining a handover support method according to an embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

110,120,130,140,150: base station

100: Handover support device

101: list provider

102: Load judgment part

103: control unit

160: terminal

The present invention relates to a WiBro (Wireless Broadband Internet) system, and more particularly, a throughput due to frequent scanning when a WiBro terminal (PSS) performs handover between frequency bands (FA). It relates to a technique that can prevent the degradation of (Throughput).

In a conventional WiBro system, a neighbor list (Neighbor List) for neighbor base station information necessary for performing a handover is periodically transmitted to a terminal. When the mobile station does not satisfy sufficient conditions during communication with the serving base station (when the power received from the serving base station is lower than the threshold), the neighbor base station included in the neighbor list received from the serving base station Scan targets (target base stations) to search for target base stations satisfying communication conditions. In this case, when the terminal scans a target base station of another frequency band other than the currently serving frequency band, the terminal requests the serving base station to stop (buffer) data transmission and reception while scanning, and thus the terminal cannot receive the service properly. That is, the throughput is reduced. In addition, when the number of target base stations of other frequency bands included in the neighbor list provided to the terminal is large, the number of scanning increases by that amount, and the throughput decreases further, resulting in poor service quality.

The present invention has been made to solve the above problems, to provide a handover support apparatus and method that can reduce the scanning time by allowing the base station to perform the hand-driven handover in the WiBro system The purpose is.

An apparatus for supporting handover in a WiBro system according to the present invention for achieving the above object includes a list providing unit for providing a neighbor list including neighbor base station information to a terminal; A load determining unit periodically checking a load ratio of a frequency band in service to the terminal to determine whether the load rate is higher than a set value; And a load list of neighboring base station information serving a serviced frequency band to the terminal when the load ratio of the frequency band in service to the terminal is lower than a set value. If it is determined that the load ratio is higher than the set value, the control unit for controlling to provide to the terminal including the neighbor base station information that serves the other frequency band in the neighbor list; It includes.

In addition, the handover support method in the WiBro system according to the present invention for achieving the above object, the neighbor list for neighboring base station information for serving the same frequency band as the serviced frequency band to the terminal to the terminal list Transmitting step; A load rate determining step of periodically checking a load rate of a frequency band in service to the terminal to determine whether the load rate is higher than a set value; And a neighbor list transmitting step of transmitting neighboring base station information serving another frequency band to the terminal when the load ratio of the frequency band in service to the terminal is higher than a set value. It includes.

The method may further include a request message reception determining step of determining whether a scanning request message for scanning a neighboring base station serving the same frequency band as the frequency band being serviced by the terminal is received.

Also, a request message receiving step of determining whether a scanning request message for scanning a neighboring base station serving another frequency band is received from the terminal; And a buffering step of stopping data transmission to the terminal and buffering for a predetermined time while the terminal scans a neighbor base station serving another frequency band when the scanning request message is received in the request message receiving determination step. can do.

Hereinafter, preferred embodiments will be described so that the present invention described above can be understood in more detail. Prior to description, FIG. 1 is a diagram for explaining a handover in a general WiBro system. For convenience of description, base stations 110, 120, and 130 (base station A, base station B, and base station C) have a first frequency. A base station serving a band (hereinafter referred to as FA1), a base station (base station D, base station E) denoted by reference numerals 140 and 150 is a base station serving a second frequency band (hereinafter referred to as FA2), and the current terminal 160 is a base station A (110). Assume that you are receiving FA1 through (serving base station).

2 is a diagram illustrating a base station 110 including a handover support apparatus 100 according to an embodiment of the present invention. As shown in FIG. 2, the handover support apparatus 100 according to the present invention includes a list providing unit 101, a load determining unit 102, and a control unit 103 (the other base stations 120, 130, 140, and 150 are also the same). Configuration).

The list providing unit 101 provides a neighbor list to the terminal 160 including neighbor base station information 120, 130, 140, and 150.

The load determining unit 102 periodically checks the load ratio of the frequency band FA1 in service to the terminal 160 to determine whether the load determination unit 102 is higher than a set value.

The control unit 103, when the load determination unit 102, the load ratio of the frequency band FA1 in service to the terminal 160 is lower than the set value, the neighboring base station serving the frequency band FA1 in service to the terminal 160. The neighbor base station providing the neighbor list for the information (120,130) and serving the other frequency band FA2 in the neighbor list when it is determined that the load rate of the frequency band FA1 in service to the terminal 160 is higher than the set value. And control information to be provided to the terminal 160 including the information 140, 150.

When the terminal 160 performs a handover from the currently serving frequency band FA1 to another frequency band (for example, FA2), while scanning the neighboring base station 140 or 150 serving the other frequency band FA2. In order to prevent the loss of data, the serving base station 110 performs buffering for a predetermined time, that is, a scanning time, without transmitting data to the terminal 160. However, since no buffering is required during the scanning operation in the same frequency band FA1 as the currently serving frequency band FA1, the problem of throughput degradation can be solved. In addition, the request for buffering may be made by the terminal 160 requesting the serving base station 110. If the load ratio of the currently serving frequency band FA1 is not high, the same frequency band as that of the currently serving frequency band FA1 is required. By transmitting only the neighbor list for the neighbor base station (120,130) serving the (FA1) to the terminal 160, it is possible to exclude the possibility of scanning the neighbor base station (140,150) serving another frequency band (FA2) that needs buffering It is. That is, the serving base station 110 may lead the terminal to perform an efficient handover.

Hereinafter, a handover support method in a WiBro system according to an exemplary embodiment of the present invention will be described with reference to FIG. 3.

1.Naver list transfer step <S210>

The terminal 160 transmits a neighbor list for neighboring base station 120 and 130 information serving the same frequency band FA1 as the frequency band FA1 in service to the terminal 160.

2. Load factor determination step <S220>

The terminal 160 periodically checks the load ratio of the frequency band FA1 in service to determine whether the terminal 160 is higher than the set value. At this time, the request message receiving determination step <S221> and the neighbor list transmission step <S230> may be performed according to the determination result.

2-1.Judged message receiving step <S221>

If it is determined in step S220 that the load rate of the frequency band FA1 serving the terminal 160 is not higher than the set value, the same frequency band FA1 as the frequency band FA1 serving the terminal 160 is determined. ) May receive a scanning request message from the terminal 160 to scan the neighboring base stations 120 and 130 serving. That is, when the terminal 160 determines that the sufficient condition for communicating with the serving base station 110 is not satisfied (when the power received from the serving base station 110 is lower than the set value), the neighboring base station (base station B (120), base station C 130, base station D 140, or any one of base station E 150) may be performed. That is, the neighbor base stations 120, 130, 140 and 150 are scanned to find the most appropriate base station. At this time, the terminal 160 transmits a scanning request message including information such as a scanning start time and a scanning start frame for scanning to the serving base station 110, and the current service is included in the neighbor list currently owned by the terminal 160. Since there is only information on neighboring base stations 120 and 130 serving the same frequency band FA1 as the current frequency band FA1, an inter-band handover (FA1? FA2) does not occur. Therefore, while the terminal 160 scans the same frequency band FA1 as the currently serving frequency band FA1, the serving base station 110 does not perform buffering, and the throughput is due to a time delay caused by the buffering. This deterioration problem does not occur. Meanwhile, if the terminal 160 performs handover by searching for a neighboring base station (for example, 130) suitable for communication due to a scanning operation, the neighboring base station 130 becomes a serving base station from then on.

In addition, when the serving base station 110 does not receive a scanning request message from the terminal 160, that is, when the serving base station 110 and the terminal 160 maintain a smooth communication state, they are currently in service. The neighbor list for neighboring base station 120 and 130 information serving the same frequency band FA1 as the frequency band FA1 may be transmitted to the terminal 160.

3.Naver list transmission step <S230>

If it is determined that the load ratio of the frequency band FA1 in service to the terminal 160 is higher than the set value in the load rate determination step <S220c>, the neighbor base station 140 and 150 serving the other frequency band FA2 is included in the neighbor list. It includes and transmits to the terminal 160. That is, when the frequency band FA1 currently being serviced is overloaded, neighboring base stations 140 and 150 serving the other frequency band FA2 are included in the neighbor list for handover between the frequency bands FA1 to FA2. The terminal 160 transmits the neighbor list to the terminal 160. Accordingly, the terminal 160 updates the neighbor list.

3-1.Judgment request stage <S231>

The terminal 160 may receive a scanning request message for scanning the neighboring base stations 140 and 150 serving the other frequency band FA2. That is, the neighboring base stations 140 and 150 serving the other frequency band FA2 are scanned to find an appropriate neighboring base station. At this time, the terminal 160 transmits a scanning request message including information such as a scanning start time and a scanning start frame for scanning to the serving base station 110. Now, the terminal 160 has a frequency other than the neighbor list of the terminal 160. Since the information about the neighboring base stations 140 and 150 serving the band FA2 is included, the neighboring base stations 140 and 150 serving the other frequency band FA2 can be scanned.

Meanwhile, when the scanning request message is not received from the terminal 160, information about the neighboring base stations 140 and 150 serving another frequency band FA2 may be included in the neighbor list and transmitted to the terminal 160. .

3-2.Buffering stage <S232>

The serving base station 110 buffers the data for a predetermined time without transmitting the data to the terminal 160 so that data is not lost while the terminal 160 scans the neighboring base stations 140 and 150 serving the other frequency band FA2. Do it.

As described above, when it is not necessary to perform the inter-band handover by determining whether to perform the inter-band handover at the serving base station (in this embodiment, the base station A 110 is assumed to be the serving base station), By transmitting only the information on neighboring base stations serving the same frequency band as the currently serving frequency band to the terminal, the terminal scans all neighboring base stations to prevent excessive buffering time. As a result, throughput is lowered and service quality can be prevented from deteriorating.

As described above, the detailed description of the present invention has been made by the embodiments with reference to the accompanying drawings, but the above-described embodiments have been described by way of example only, and thus the present invention is limited to the above embodiments. It is not to be understood that the scope of the invention should be understood by the claims and equivalent concepts described below.

As described in detail above, according to the present invention, the serving base station transmits neighboring base station information serving another frequency band to the terminal only when handover between frequency bands is necessary, thereby scanning neighboring base stations serving other frequency bands from time to time. By reducing the unnecessary buffering time that can occur, it is possible to solve the problem that the throughput is severely degraded, and to provide a quality WiBro service.

Claims (4)

delete delete A neighbor list transmission step of transmitting to the terminal a neighbor list for neighbor base station information serving a same frequency band as a frequency band being serviced to the terminal; A load rate determining step of periodically checking a load rate of a frequency band in service to the terminal to determine whether the load rate is higher than a set value; And A neighbor list transmitting step of transmitting neighboring base station information serving another frequency band to the terminal when the load ratio of the frequency band in service to the terminal is higher than a preset value; Including; And a request message receiving step of determining whether a scanning request message for scanning a neighboring base station serving the same frequency band as the frequency band being serviced by the terminal is received from the terminal. How to support handover. A neighbor list transmission step of transmitting to the terminal a neighbor list for neighbor base station information serving a same frequency band as a frequency band being serviced to the terminal; A load rate determining step of periodically checking a load rate of a frequency band in service to the terminal to determine whether the load rate is higher than a set value; And A neighbor list transmitting step of transmitting neighboring base station information serving another frequency band to the terminal when the load ratio of the frequency band in service to the terminal is higher than a preset value; Including; A request message receiving step of determining whether a scanning request message for scanning a neighboring base station serving another frequency band is received from the terminal; And Buffering the data transmission to the terminal and buffering for a predetermined time while the terminal scans a neighboring base station serving another frequency band when the scanning request message is received in the request message receiving determination step; Handover support method in a WiBro system, characterized in that.

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