KR100492414B1 - Method for administrating neighbor list in cdma system - Google Patents

Abstract

The present invention relates to a method for managing neighboring base station information for detecting a non-entry list of neighboring base stations and a mis-entry which is one of call interruption factors in a CDMA system, and to solve this problem, code division multiple access (CDMA) according to the present invention. The neighbor base station information management method of the system is: In a CDMA system, if a handoff failure is detected while performing a handoff at the request of a mobile station, the neighbor base station list of the current cell and the neighbor base station list of the handoff attempted cell are retrieved. Comparing neighboring base station list information of the current cell and neighboring base station list information of the handoff attempted cell; and as a result of the comparison, neighboring base station list information of the current cell and neighboring base station list information of the handoff attempted cell. If different, the neighbor base station list information of the handoff attempted cell Updating the neighbor base station list information of the mobile station; requesting and receiving neighbor base station list information of the mobile station requesting the handoff; and neighboring base station list information of the mobile station neighbor base station list information and the updated handoff attempted cell; Comparing the neighboring base station list information of the mobile station with the neighboring base station list information of the handoff attempted cell if the neighboring base station list information of the mobile station and the neighboring base station list information of the updated handoff attempted cell are different. And retrying the handoff by using the updated neighbor base station list information.

Description

Information management method of adjacent base station of CDMA system {METHOD FOR ADMINISTRATING NEIGHBOR LIST IN CDMA SYSTEM}

The present invention relates to a method for managing neighboring base station information in a CDMA system. In particular, the present invention relates to a neighbor base station information by analyzing a handoff failure call in order to find a non-entry list of neighboring base stations, which is one of disconnection factors during a call in the CDMA system. It is about how to manage.

Code Division Multiple Access (hereinafter referred to as "CDMA") scheme, which is rapidly evolving due to the success of commercial service in our country, is a base station (hereinafter referred to as "base station" or "BS".) And a mobile station (hereinafter referred to as "mobile station" or "MS") means a signal transmission method, the use of satellite positioning system GPS (Global Positioning System) of the base station Are divided into synchronous and asynchronous.

Such a CDMA system can be roughly classified into a mobile switching center (MSC), a base station, and a mobile station (terminal).

The configuration of the CDMA system is briefly described as follows.

The exchange station is connected to each base station controller (hereinafter referred to as a "base station controller" or "BSC"), information and authentication for the subscriber, information on the associated additional equipment, and information about the location and registration of the mobile station. It is composed of and plays the role of making connection with other networks. Such an exchange has a function to handle calls and calls from each base station and to connect with an exchange in a public switching telephone network (PSTN) with a central control function so that all base stations can be efficiently operated. It is composed of call path and peripheral devices, and it also has a billing data search function for calls completed.

The base station is composed of a base station controller (BSC), a base station transmitter (BTS) and a repeater (Cell Enhancer), etc., the mobile station is connected to the switching station to make a call with the other party.

The mobile station consists of a radio transceiver, an antenna and a control device.

The mobile station, the base station, and the switching center are connected to each other by a call line and a data link. The CDMA system of this connection structure uses a pair of transmit and receive radio channels when each mobile station makes a call, but the channel is fixed to a specific frequency channel. It can be changed to another channel according to the movement of the terminal even during a call, so that a call can be made to any channel if the channel is allocated to the region.

In addition, the CDMA system is composed of many units. In addition to the above-described switching center base station (base station controller and base station transmitter) and mobile station, the CDMA system has a complex configuration including a transmission path, vocoder, channel, frequency, subcell and other equipment.

Of course, when the terminal is far from the base station, the signal strength is weakened. Therefore, in order to receive continuous service, the terminal must move to a neighboring base station where a strong radio wave is received. In such a CDMA system, a process of smoothly maintaining a call of a mobile station moving between a base station and a base station during a call is referred to as handoff or handover.

When a terminal talking to a specific base station loses signal (wave strength) at that base station, a handoff to a neighboring base station includes soft handoff, softer handoff, and hard handoff. There are three types, and each handoff is again technically divided in several ways.

Dual soft handoff is a handoff method that prevents any call during the movement between the base station and the base station during a call. FDMA (Frequency Division Multiple Access (FDMA)) in which a call transfer occurs when a mobile station moves between cells. Unlike time division multiple access (TDMA) and CDMA, all cells use the same frequency, so that seamless handoff is possible during handoff. Soft handoff is a method of connecting a call through an intermediate process of simultaneously acquiring signals from both base stations. This is called "Connect before Break" or "Make and Break".

This soft handoff is possible only when both base stations are configured with the same frequency because the mobile station is configured with one frequency H / W, and the demodulators of the mobile station come from different base stations (or with different time delays). Signal), which is enabled by a demodulator called a finger, which separately demodulates. Since the finger of the mobile station has three demodulator functions, it is possible to simultaneously perform handoff with three base stations.

In order to determine access to neighboring base stations when the mobile station moves between base stations, it is necessary to search for pilot PN offsets of neighboring base stations. In practice, however, the number of base stations consists of hundreds or thousands, which makes realistic searching impossible. Therefore, in order to efficiently search for the pilot signal of the neighboring base station, the mobile station must know the PN offset information of the neighboring base station in advance. That is, the current base station should inform the mobile station of information such as the PN offset and frequency of the neighboring base station close to the mobile station, and the mobile station should first search for the neighbor base station pilot signal indicated by the current base station.

Such neighbor base station PN offset information is referred to as a neighbor base station list (Neighbor List), and this information must be continuously updated from the base station whenever the mobile station is first turned on or the base station is changed through handoff.

On the other hand, the mobile station performs handoff not only in the call state but also in the call waiting state. The process of changing a base station by moving during a reception wait is called an idle handoff. At this time, the mobile station compares the Ec / Io (signal-to-noise ratio in the pilot channel) with the neighboring cell and switches to a base station of a sufficiently large side (3 dB or more). A call is made to the indication state of the base station.

Call waiting handoffs are fundamentally different from handoffs in a call state, in that they do not exchange any messages with the base station for handoffs, but rather determine by the mobile station itself. Of these important information, the neighbor base station list indicating the neighbor base station PN offset is used to prepare for handoff to the neighbor base station again.

That is, during the reception standby, the "Neighbor List Message" is received through the call channel, and when the base station is changed to the handoff during the call, the "Neighbor List Update Message" is received through the call channel. Manage offset information.

However, these messages are transmitted and received between the base station and the mobile station, and the neighbor base station lists held between neighboring base stations are not automatically added or modified identically to each other. Therefore, in case of inconsistency in the list of neighboring base stations, if the administrator needs to update the list of neighboring base stations by hand, not only causes the data inconsistency to overlap, but also causes the channel exchange of the system that is frequently performed according to the inconsistency. This reduces the efficiency of the system.

Therefore, if the neighboring base station list is not properly input or is an incorrect list, the mobile station in the call performs a handoff based on PN offset information of incorrect base stations. In addition, if a mobile station waiting for a call receives a neighbor base station list message including a neighbor base station list or incorrect neighbor base station information from the base station, the mobile station not only performs an incorrect handoff but also continues normal call waiting and handing. There was a problem that the off could not be performed.

In addition, the call disconnection phenomenon caused by the error of the neighboring base station list is difficult to search, so it is necessary to check the field directly, and the administrator must directly input and modify it.

Accordingly, an object of the present invention is to provide a method for searching neighboring base station information in order to find a non-input and a wrong input of neighboring base station information, which is one of the disconnection factors of the CDMA system.

Another object of the present invention is to provide a neighbor base station information management method capable of confirming the absence of neighbor base station information in a CDMA system, and modifying and adding neighbor base station information.

In order to solve the above object, the present invention is a code division multiple access (CDMA) system, when a handoff failure is detected in the process of performing a handoff at the request of a mobile station, the neighbor base station list of the current cell and a handoff attempt Searching for a neighbor base station list of a cell; comparing neighbor base station list information of the current cell with neighbor base station list information of the attempted cell; and comparing the neighbor base station list information of the current cell with the handoff result; Updating neighboring base station list information of the handoff attempting cell to neighboring base station list information of the current cell if the neighboring base station list information of the attempted cell is different; requesting and receiving neighboring base station list information of the mobile station requesting the handoff; Process,

Comparing neighboring base station list information of the mobile station with neighboring base station list information of the updated handoff attempting cell; and if the neighboring base station list information of the mobile station is different from neighboring base station list information of the updated handoff attempting cell, the mobile station And updating the neighbor base station list information of the neighbor base station list information to the neighbor base station list information of the handoff attempted cell, and retrying the handoff by using the updated neighbor base station list information.

In addition, the present invention, in the process of updating the neighbor base station list information of the handoff attempt cell to the neighbor base station list information of the current cell, the neighbor base station list of the current cell and the neighbor base station list of the handoff attempt cell, the neighbor base station list And displaying, in the window, and adding, deleting, sorting, moving, and exchanging neighboring base station list information of the current cell to neighboring base station list information of the handoff attempt cell according to the administrator's update request.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same components have the same reference numerals as much as possible even if they are displayed on different drawings. Detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a diagram showing the configuration of a CDMA system to which the present invention is applied.

1 illustrates an authentication, registration, and system of a base station subsystem, which is roughly divided into a mobile station, a base station, and a base station controller, a wireless switching and management subsystem, which is roughly divided into a switching station and various switching stations switching to the Internet or public telecommunication networks. It shows the composition of the mobile communication system including the operation and management subsystem which is divided into the overall operation and management center.

As shown, the mobile station and the base station perform wireless communication, and include a base station controller controlling one or more base stations and an exchange station for switching signals between base stations controlled under different base station controllers. The switching center is also connected to an external public telephone network or other mobile communication network through a gateway switching center and / or an international switching center.

Referring to FIG. 1 in more detail, first, the CDMA system shown in FIG. 1 is a mobile station (MS-A, B, C) 10, 12, 14, a base transceiver station (BTS-A, B, C). (20, 22, 24), Base Station Controller (BSC # 1, # 2) (30, 32), Mobile Switching Center (MSC) 100, EIR (Equipment Identity Register) 102 , Authentication Center (AUC) 104, Home Location Register (HLR) 106, Visited Location Register (VLR) 108, Gateway MSC (GMSC) 40, and International Switching Center (ISC) 50 It is composed. And the OMC (Operation Maintenance Center) 60 for monitoring, operating and managing the state of these components operates in conjunction with the equipment of each system.

The mobile stations (MS-A, B, C) (10, 12, 14) is composed of a radio transceiver, an antenna, and a control device to perform a voice service and a packet data service while moving.

The base station BS is a base station transmitter (BTS-A, B, C) 20, 22, 24, a base station controller (BSC # 1, # 2) 30, 32, and a repeater (Cell Enhancer) (not shown). The mobile station 10, 12, 14 is connected to the switching station 100 to make a call with the desired counterpart.

The switching center 100 is composed of connection with each base station controller (BSC # 1, # 2) (30, 32), information and authentication for subscribers, and related additional equipment, and plays a role of making a connection with other networks. do. In addition, the switching center 100 processes calls and calls from each base station controller BSC # 1 and # 2, and provides a central control function so that all base station controllers BSC # 1 and # 2 can be efficiently operated. It also connects to the switching center of the Public Switching Telephone Network (PSTN) through the trunk line, and consists of a control unit, a call path and peripherals, and retrieves billing data for calls that have been completed and maintained. It also has a function. The switching center 100 registers the location of the subscriber so that the system can keep track of the subscriber's moving position in association with the Home Location Register (HLR) 106 and the Visified Location Register (VLR) 108. The HLR 106 is a database that stores basic subscriber information and location information such as personal information, subscription service type, and terminal type of the subscriber, and the VLR 108 is a subscriber to reduce frequent inquiries and updates of the HLR 106. It is a database in the form of RAM (Random Access Memory) that temporarily stores the subscriber's simple phone number, terminal information, location information, etc. in a base station or exchange that manages an area in which the location is located.

The EIR 102 performs identification information for system security by registering identification information of a device interworking in the system for operation and management of the system.

The AUC 104 manages an encryption key associated with a subscriber and can be located within the HLR 106 or the switching center 100.

The mobile stations (MS-A, B, C) (10, 12, 14), base station transmitters (BTS-A, B, C) 20, 22, 24, base station controllers (BSC # 1, # 2) 30 32) and the switching center (MSC) 100 are connected to each other by a call line and a data link, and the CDMA system of this connection structure allows each mobile station (MS-A, B, C) 10, 12, 14 to make a call. When using a pair of transmit and receive radio channel, but the channel is not fixed to any specific frequency channel and can be changed to another channel according to the movement of the terminal during the call, so that the channel assigned to the region can be used to call any channel. .

The mobile station (MS-A) 10 moves from the current cell 70 to the position of the mobile station MS-B of the adjacent cell 80, and in the current BTS-A 20, the " BTS 22 " I need a handoff because the signal from) is bigger. ” The current BTS-A 20 then informs BSC # 1 30 that the BTS-B 22 finds and communicates with the mobile station (MS-A) 10 through paging. If the cell in which the mobile station (MS-C) 14 to which the mobile station (MS-A) 10 is to be newly moved is located does not belong to the BSC # 1 (30) to which the cell 70 belongs, the BSC does not belong together. If cell 90 belongs to # 2 32, BSC # 1 30 informs MSC 100 of the handoff request of mobile station (MS-A) 10, and BTS-C24 again. After finding the corresponding BSC # 2 32 under control, the BTS-C 24 finds and communicates with the mobile station (MS-A) 10 through paging under the control of the BSC # 2 32.

In particular, the base station controller (BSC # 1, # 2) (30, 32) is provided with a neighbor base station list information search tool according to the present invention, the neighbor base station of each cell under control by driving the neighbor base station list information search tool And a database for retrieving and storing list information, and displaying a list of handoff attempted cells and neighboring base stations of the current cell under the control of an administrator. In addition, the base station controllers 30 and 32 add the neighbor base station list information of the current cell to the neighbor base station list information of the handoff attempt cell with respect to the displayed handoff attempt cell and the neighbor cell base station list of the current cell under the control of an administrator. Add, delete, sort, move, exchange.

2 is a control flowchart illustrating a method for managing neighbor base station information between neighboring base stations in a CDMA system according to an exemplary embodiment of the present invention, and FIG. 3 is a list of neighbor base station information when handoff fails in a CDMA system according to an exemplary embodiment of the present invention. The figure shows the neighbor base station list search window for modification and update.

Hereinafter, a method of managing neighboring base station information for finding a non-entry base station list non-input and a wrong input, which is one of call disconnection factors, in the CDMA system according to the present invention will be described in detail with reference to FIGS.

The neighbor base station information management method of the code division multiple access (CDMA) system according to the present invention is a mobile station (MS-B) (as shown in Figs. 1 and 2) at the request of a mobile station (MS-A) 10; If a handoff failure is detected in the process of performing the handoff to the position of 12) (step 202), the base station controller (BSC # 1) 30 determines the base station list of the current cell 70 by the base station. A request is made to the transmitter (BTS-A) 20, and the base station transmitter (BTS-B) 22 is requested to retrieve the neighbor base station list of the handoff attempt cell 80 (step 206).

Information about the neighbor base station list of the searched current cell 70 and the neighbor base station list of the handoff attempt cell 80 is displayed in the neighbor base station list window shown in FIG. Subsequently, the BSC # 1 30 compares the neighbor base station list information of the current cell 70 with the neighbor base station list information of the handoff attempt cell 80 even without special control of the manager (step 208).

The neighbor base station list information displayed in the neighbor base station list window has main fields such as NGHBR_PN, NGHBR_BAND, NGHBR_FREQ, SEARCH_PRIORITY, and FREQ_INCL indicating the PN_OFFSET value of the cell to be registered as the neighbor base station of the current cell. In addition, it displays a unique value of a corresponding cell such as PN_OFFSET, SID (System Identification), NID (Network Identification), which are fixed data values required for the first generation of a neighboring base station list of the cell.

It is also possible to search the list of neighboring base stations under the control of the administrator.

If the neighboring base station list information of the current cell 70 and the neighboring base station list information of the handoff attempt cell 80 are different from each other as a result of the comparison, the BSC # 1 30 may determine the neighbor base station list information of the handoff attempt cell 80. The neighbor base station list information of the current cell 70 is updated (step 210).

Meanwhile, as shown in the lower part of FIG. 3, the information about the neighbor base station list of the searched current cell 70 and the neighbor base station list of the handoff attempt cell 80 may be determined by the administrator. An operation of adding, deleting, modifying, moving, and swapping neighboring base station list information of the current cell 70 to the neighboring base station list information of 80 is performed.

Subsequently, the BSC # 1 30 requests and receives neighbor base station list information of the mobile station (MS-A) 10 that has requested the handoff (step 212). The neighbor base station list information of the received MS-A 10 is displayed in the neighbor base station list window for comparison with the neighbor base station list information of the updated handoff attempted cell.

The BSC # 1 30 determines that the neighboring base station list information of the MS-A 10 and the neighboring base station list information of the updated handoff attempt cell 80 are different from the MS-A. The neighbor base station list information of (10) is updated with the neighbor base station list information of the handoff attempt cell 80 (step 216).

Accordingly, the MS-A 10 retries the handoff using the updated neighbor base station list information (step 218).

On the other hand, in the detailed description of the present invention has been described with reference to specific embodiments, of course, various modifications are possible without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, in the present invention, since the administrator can easily perform a search and update on a call disconnection phenomenon due to a neighbor base station list error in a CDMA system, the administrator can easily perform a search using a search tool. There is an advantage in that input and modification can reduce wasted time and manpower.

1 is a diagram showing the configuration of a CDMA system to which the present invention is applied;

2 is a control flowchart illustrating a method for managing neighboring base station information when a handoff fails in a CDMA system according to an embodiment of the present invention;

3 is a diagram illustrating a neighbor base station list search window for modifying and updating neighbor base station list information when a handoff fails in a CDMA system according to an exemplary embodiment of the present invention;

Explanation of symbols on main parts of the drawing

10, 12, 14: mobile station (MS) 20, 22, 24: base station transmitter (BTS)

30, 32: base station controller (BSC) 40: gateway MSC (GMSC)

50: International Exchange Bureau (ISC) 60: Operational Bureau (OMC)

100: MSC 102: Device Identification Information Register (EIR)

104: authentication center (AUC) 106: home location register (HLR)

108: Visitor Location Register (VLR)

Claims (2)

In a code division multiple access (CDMA) system, Retrieving the neighbor base station list of the current cell and the neighbor base station list of the handoff attempted cell if a handoff failure is detected in the process of performing handoff according to the request of the mobile station; Comparing neighbor base station list information of the current cell with neighbor base station list information of the handoff attempted cell; Updating neighboring base station list information of the handoff attempted cell to neighboring base station list information of the current cell if the neighboring base station list information of the current cell and the neighboring base station list information of the handoff attempt cell are different as a result of the comparison; Requesting and receiving the neighbor base station list information of the mobile station requesting the handoff; Comparing neighbor base station list information of the mobile station with neighbor base station list information of the updated handoff attempt cell; Updating neighboring base station list information of the mobile station to neighboring base station list information of the handoff attempting cell if the neighboring base station list information of the mobile station and the neighboring base station list information of the updated handoff attempt cell are different; And retrying the handoff using the updated neighbor base station list information. The method of claim 1, The step of updating the neighbor base station list information of the handoff attempt cell to the neighbor base station list information of the current cell may include: Displaying the neighbor base station list of the current cell and the neighbor base station list of the handoff attempt cell in a neighbor base station list window; A method of managing neighbor base station information in a CDMA system, comprising adding, deleting, sorting, moving, and exchanging neighbor base station list information of a current cell to neighbor base station list information of the handoff attempted cell according to an administrator's update request. .