KR100873678B1 - Idle hand off method for mobile terminal - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle handoff method of a mobile terminal. In particular, the mobile terminal has a high-speed movement by using distance information with an adjacent base station for idle handoff of a mobile terminal having a GPS (Global Positioning System) function. Also relates to an idle handoff method of a portable terminal capable of providing a high quality service. The idle handoff method of the conventional mobile terminal may correspond to a handoff occurring after the scan of a plurality of base stations is completed and the generation of the handoff candidate group is completed, but the handoff is performed before the scan is performed due to the fast movement of the mobile terminal. In case of requesting a proper handoff base station, there is a problem that the quality of service is lowered or the transmission / reception is impossible. In view of the above problems, the present invention includes the steps of receiving a list of neighboring base stations and corresponding base station location information from a service base station and storing them in a terminal; Receiving the terminal's own location information from the serving base station and sequentially scanning the strength of the pilot channel signal from the nearest base station to generate a candidate base station group to be handed off; By providing the method, it is possible to ensure a smooth handoff during high-speed movement of the mobile terminal, thereby providing an effect of providing a high quality communication service.

Description

Idle handoff method for mobile terminal {IDLE HAND OFF METHOD FOR MOBILE TERMINAL}

1 is a block diagram showing a general handoff occurrence situation.

Figure 2 is a flow chart of one embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: terminal 20: first base station

30: second base station 40: third base station

50: base station 4 60: base station 5

70: base 6 station 80: base 7 station

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle handoff method of a mobile terminal. In particular, the mobile terminal can use the distance information with a neighbor base station for idle handoff of a mobile terminal having a GPS (Global Positioning System) function. Also relates to an idle handoff method of a portable terminal capable of providing a high quality service.                         

With the increasing use of mobile terminals, interest in call quality of mobile terminals is increasing. Higher handset call quality is an essential condition for the use of current handheld terminals with added functionality.

As the use of portable terminals increases, the cases of moving at high speeds with portable terminals become frequent. The high speed movement of the portable terminal causes various technical problems, and the most basic problem is a handoff occurring when moving between base station areas.

Here, the idle handoff of the CDMA terminal will be described.

The mobile terminal periodically attempts to communicate with the currently serving base station, thereby sharing information such as the location and service status of the mobile terminal with the base station. However, one base station is in charge of controlling only the mobile terminal located within the set area, and when the mobile terminal moves out of the base station area to the adjacent base station, the control is transferred to the base station.

This transfer of the control right is called a handoff. For this purpose, the mobile terminal should measure the signal strength of the neighboring base stations by obtaining information about neighboring base stations from the currently serving base station.

1 illustrates a general base station configuration, in which a plurality of base stations having overlapping areas are arranged. If the mobile terminal 10 moves from the first base station 20 to the fourth base station 50, the base station currently providing the service becomes the first base station 20.                         

When the portable terminal 10 moves from the first base station 20 area to the fourth base station 50 area as described above, the portable terminal 10 connects to the fourth base station 50 and simultaneously performs two base stations 20. , 50), and then move to the area of the fourth base station 50 to release the communication with the first base station 20.

To this end, the mobile terminal 10 should know information about neighboring base stations 30 to 80, and should know the signal strength of each adjacent base station 30 to 80, and thus have a base station having an optimal signal strength (in this case, fourth). Handoff may be made to the base station 50.

The mobile terminal 10 communicates with the first base station 20 serving as a service base station in an idle state (standby state) to receive and store a list of adjacent base stations 30 to 80. In addition, the pilot channel signal magnitudes of the adjacent base stations 30 to 80 are measured at predetermined intervals to generate candidate groups for handoff. The signal magnitude measurement is called a scan, with priority given to base stations with past access.

For example, if the mobile terminal 10 is moving past the seventh base station 80, the priority of the first scan becomes the seventh base station 80.

By generating the handoff candidate group by periodically measuring the pilot channel signal magnitudes of the neighboring base stations 30 to 80 by the above-described method, if the signal of the first base station 20 that is currently providing the service is weakened, Handoff is made to the base station (herein, the fourth base station 50) having the best signal strength.

In the figure, although the number of base stations is small, there are usually 10 or more base stations around the terminal, and in most cases, the highest signal strength is shown in geographically adjacent base stations. In the figure, the terminal 10 shows the largest signal strength at the first base station 20 and the fourth base station 50. Therefore, it is normal that the handoff is performed to the fourth base station 50 in the manner described above.

However, when the mobile terminal 10 moves at a high speed, even if the mobile terminal 10 receives a list of neighboring base stations from the first base station 20 serving as a serving base station, the portable terminal 10 cannot scan the neighboring base stations. There is a case.

In this case, the probability that the fourth base station 50, which is the handoff candidate base station having the largest signal strength, is selected is 1/6. In general, if there are n neighbor base stations, the probability is 1 / n, so that an ideal handoff is not made.

For example, the second base station 30, the sixth base station 70, the third base station 40, the fifth base station 60, and the fourth base station starting with the seventh base station 80 having the scanning priority. 50, if any base station (for example, the second base station 30) is selected due to the rapid movement, communication with the mobile terminal 10 entering the area of the fourth base station 50 is lost. Will occur.

Even if the communication is not lost, the service is not provided with good quality while scanning the signal strengths of the base stations according to the scanning order.

As described above, the idle handoff method of the conventional mobile terminal may correspond to a handoff occurring when the scan of a plurality of base stations is completed and the generation of the handoff candidate group is completed, but the scan is performed due to the fast movement of the mobile terminal. If a handoff is required before the service is performed, there is a problem in that the quality of service is lowered or the transmission / reception is impossible due to failure to determine an appropriate handoff base station.

In view of the above problems, the present invention stores location information of each base station along with a list of adjacent base stations when performing idle registration of a mobile terminal having a global positioning system (GPS) function, and physically adjacent base stations. It is an object of the present invention to provide an idle handoff method of a portable terminal, which enables proper handoff even at a high speed movement of the portable terminal.

According to an aspect of the present invention, there is provided a method comprising: receiving a list of neighboring base stations and corresponding base station location information from a service base station and storing the received base station location information in a terminal; And receiving the location information of the terminal from the serving base station and sequentially scanning the strength of the pilot channel signal from the nearest base station to generate a candidate base station group to be handed off.

Periodically receiving, by the terminal, its own location information and arranging the scanning order of neighboring base stations in the adjacent order; And performing a scan in the sorting order to generate a candidate base station population for handoff.

An embodiment of the idle handoff method of the present invention as described above will be described in detail with reference to the accompanying drawings.

The basic operation of the present invention will be discussed using the configuration of FIG.

In order to use the present invention, a first base station 20 providing a service to a terminal 10 provides information on neighboring base stations when the terminal 10 registers in an idle state. However, it should be noted that not only providing a list of neighboring base stations but also simultaneously provides location information of the corresponding base stations. Currently, the base stations know their absolute location (latitude / longitude) and can measure the location of the terminal 10 to know the location information of the corresponding terminal 10. This is known to those skilled in the art.

Therefore, when the terminal 10 registers, the service base station provides a list and location information of neighboring base stations 30 to 80, and provides the GPS service to the terminal 10 when the terminal 10 requests it.

The terminal 10 used in the present invention stores the list of neighboring base stations and the location information received from the service base station 20 in the terminal, and periodically requests the base station 20 to receive its own location information to receive the adjacent information. The scan order of the base stations 30 to 80 is performed in the order of the nearest position to generate the handoff set.

Therefore, since the priority of the scan is the geographically closest base station (here, the fourth base station 50), even if the mobile terminal 10 moves at a high speed, the hand is moved to the adjacent base station 50 having good signal strength. Off may be performed.

FIG. 2 is a flow chart showing a sequence of an embodiment of the present invention, in which a terminal enters an idle state and registers as shown in the drawing; A second step of receiving an improved neighbor base station list (including location information) from the serving base station through the above step and storing it internally; A third step of periodically receiving the geographic location information of the terminal from the serving base station and scanning from the neighboring base station nearest the geographical location; A fourth step of generating a handoff candidate group by measuring the strength of pilot channel signals of all neighboring base stations through the step; If the signal strength of the serving base station is greater than or equal to the threshold value, the process returns to the third step. If the signal strength decreases to less than or equal to the threshold value, the fifth step is performed.

This will be explained in more detail.

First, when the terminal enters the idle state and performs registration, it receives information about neighboring base stations from the base station.

The received information about neighboring base stations is a list including the locations of neighboring base stations, which are stored internally in the terminal.

Then, periodically receiving the terminal's own location information from the service base station, the service base station should provide the GPS service at the request of the terminal. Through the above process, the terminal measures its distance from neighboring base stations, arranges the scan order in close order, and performs the scan accordingly.

Through this step, the strength of the pilot channel signals of all neighboring base stations is measured to generate a handoff candidate group, which is constantly changed according to the movement of the terminal periodically.

If the mobile terminal moves at a high speed, even if the scan is not completed, the scan sequence itself has the closest base station as a priority, so a handoff with a base station having a good signal strength may occur, thereby improving transmission and reception rates. The same quality improvement is achieved.

If the signal strength of the serving base station is greater than or equal to the threshold, the periodic scan as described above is repeated. If the signal strength decreases to less than or equal to the threshold, the mobile terminal can perform a high speed by handing off to a base station having good signal strength among the handoff candidates. When not moving, the communication quality is increased because the neighboring base stations are first scanned and placed in the handoff candidate group.

As described above, the idle handoff method of the mobile terminal of the present invention allows the mobile terminal to receive the neighbor base station list and the location information from the service base station and periodically scans from the nearest base station using the terminal location information. Smooth handoff can be ensured at high speeds, thereby providing a high quality communication service.

Claims (2)

Periodically receiving a list of neighboring base stations and location information of corresponding base stations from a service providing base station and storing the location information in the terminal; Receiving the location information of the terminal itself from the service providing base station, the strength of the pilot channel signal Generating a list of candidate base stations to be handed off by sequentially scanning from the nearest base station. The method of claim 1, wherein the generating of the candidate base station list Comparing the periodically received location information of the terminal with the location information of the base stations and arranging the scanning order of adjacent base stations in the adjacent order; And periodically generating candidate list of candidate base stations for handoff by performing the scanning in the sorting order.

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