KR100639322B1 - A method of cell selection for wll terminal - Google Patents

Abstract

The present invention relates to a method of cell selection in a fixed terminal used in a WLL system, and more particularly, by a base station using a sector antenna to check the signal strength of each cell to automatically select a cell having excellent signal strength. And an alpha process of inputting an encoding value of an alpha cell into a terminal, checking a frequency environment of the alpha cell, and storing the same in an allocated memory; A beta process of adding a first P & P value to an alpha P & P value to be a P & P value of a beta cell, checking a frequency environment of the beta cell, and recording and storing the beta cell in an allocated memory; A gamma process of adding a predetermined second P & P value to an alpha P & P value to be a P & P value of the gamma cell, identifying a frequency environment of the gamma cell, and storing the same in the memory; A cell selection process of selecting cells having the best frequency environment by comparing and analyzing the values recorded in the memory; An opening process of registering a terminal with the selected cell and allocating a communication channel; A communication process of connecting and communicating with a terminal through an assigned channel; An end determination step of determining whether to end the communication; A monitoring process to check whether the frequency environment of the adjacent cell is better; When the frequency environment of the neighboring cell is better in the monitoring process, the terminal is registered with the neighboring cell, the communication channel is allocated, and at the same time, the switching channel is allocated to the assigned channel and maintains communication.

Description

Cell selection method of wireless subscriber network terminal {A METHOD OF CELL SELECTION FOR WLL TERMINAL}

1 is a block diagram of a general wireless subscriber network system,

2 is a flowchart of opening by cell selection of a wireless subscriber network terminal according to the prior art;

3 is a cell selection flowchart of a wireless subscriber station terminal according to the present invention.

          ** Explanation of symbols for the main parts of the drawing **

10: central control unit 20: base station

30,31,32: terminal 40: cell

The present invention relates to a method for selecting a cell in a fixed terminal used in a wireless local loop (WLL) system. In particular, a signal of each cell in a base station using a sector antenna The present invention relates to improving the quality of service by checking the strength and automatically selecting a cell having excellent signal strength.

The wireless subscriber network (WLL) system applies or utilizes a cellular mobile communication system as it is. However, when a terminal moves between a base station (BTS) or a cell, a new channel is automatically allocated for continuity of communication. It does not provide only a hand-over function, and the terminal is to be fixedly used.

Each base station used in the wireless subscriber network is divided into three sectors or cells of α, β, and γ by using a sector antenna, or one omni antenna is used. The cells are divided into one cell, and each cell generates an overlapped part.

As described above, the WLL terminal, which is located in the overlapping part of the cell, communicates through a specific cell, and communicates through the currently connected cell even when the wireless environment from the neighbor cell is better due to the change of the surrounding environment. You must proceed.

If the radio environment of the neighboring cell is better as described above, the connection with the cell currently being communicated is stopped, the registration application and confirmation are received at the neighboring cell, and the channel is allocated and the communication is performed by the assigned channel. All opening procedures must be repeated anew.

Hereinafter, a cell selection method of a wireless subscriber network terminal according to the prior art will be described with reference to the accompanying drawings.

Attached to explain the prior art, Figure 1 is a block diagram of a general wireless subscriber network system, Figure 2 is a flow chart of opening by cell selection of the wireless subscriber network terminal according to the prior art.

Referring to FIG. 1, the general wireless subscriber network (WLL) system includes a central controller 10 for monitoring and managing the entire wireless subscriber network system and performing necessary control functions.

A base station (BTS) 20 connected to the central controller 10 by wire and wirelessly transmitting and receiving;

Located in the cell (40) which is a service area of the base station 20, it is composed of a plurality of stationary terminal stations (30, 31, 32) in wireless communication with the base station (20).

In addition, referring to the accompanying Figure 2, the opening sequence by the cell selection of the wireless subscriber network terminal according to the prior art, the first step (S10) to request registration by transmitting a unique number (ID) of the terminal to the cell located; )Wow,

The central control unit 10 of the wireless subscriber network, which has received the unique number (ID) of the corresponding terminal (30, 31, 32) through the base station 20 by the first step (S10), searches the database. And determining or confirming whether the terminal is a registered terminal (S20);

If the terminal is confirmed and registered in the second step, the central control unit 10 allocates a communication channel to the corresponding terminal (30, 31, 32) (S30),

The corresponding terminal (30, 31, 32) assigned the communication channel by the third step (S30) is a fourth step (S40) for performing communication through the assigned channel,

The terminal 30, 31, 32 performs a communication, the fifth step (S50) for determining whether the frequency environment or signal quality of the adjacent cell is excellent;

As a result of the determination of the fifth step (S50), when the frequency environment of the adjacent cell is better, the sixth step (S60) for determining whether to communicate through the adjacent cell,                         

As a result of the determination of the fifth step (S50), if the frequency environment of the neighboring cell is not better, it is determined whether to terminate the communication currently in progress. A seventh step S70 of feeding back to the fourth step S40,

If it is determined in the sixth step (S60) that communication is not performed through the neighbor cell, the process proceeds to the seventh step (S70), and when communicating through the neighbor cell, the current communication ends and the first step It consists of an eighth step (S80) to feed back.

Hereinafter, with reference to the accompanying drawings, the cell selection and opening procedure of the terminal according to the wireless subscriber network configuration and the prior art as described above will be described in detail.

The base station 20 has a service area which is divided into three cells of α cell, β cell and γ cell by using a sector antenna, and the area of the corresponding cell is not clearly distinguished at the boundary of each cell. As the area of the cell changes slightly due to the change of the surrounding environment, the terminal 30, 31, 32 in the fixed position slightly changes the frequency environment received from the cell.

The terminal 30, 31, 32 requests registration by sending a terminal unique number (ID) to the central controller 10 through the finally communicated cell (S10), and the central controller 10 transmits the corresponding data. The base DB is searched to determine and determine whether the terminals 30, 31, and 32 are registered (S20), and when the terminal 30, 31, or 32 is confirmed, the communication channel is allocated to the terminal. (S30).

The terminal 30, 31, 32 proceeds with communication through the assigned channel (S40), and determines whether the frequency environment of the neighbor cell is excellent (S50), if the frequency environment of the neighbor cell is excellent, If it is determined whether to communicate through the neighboring cell (S60), if you want to proceed with the communication through the neighboring cell, after the ongoing communication through the current cell (S80), the feedback to the first step (S10) ( Feedback), and the above cell selection and opening procedure is performed again.

If the frequency environment of the neighboring cell is not excellent in the fifth step S50 or if the communication is not performed through the neighboring cell in the sixth step S60, it is determined whether to terminate the ongoing communication through the currently connected cell. (S70), if it ends, the process proceeds to the end step, and if the communication continues, the process returns to the fourth step S40 to continue the ongoing communication.

Accordingly, the wireless subscriber network (WLL) terminals 30, 31, and 32 according to the prior art communicate with each other through the neighbor cell in a state where the frequency environment of the neighbor cell is superior to the frequency environment of the cell currently in communication. If this is to be done, there is a problem that the current ongoing communication is terminated and the above-mentioned opening procedure is to be repeated through the adjacent cell.

In case of re-opening the sequence as described above, since the communication is stopped and time is required, the communication requiring the emergency has a bad frequency environment and must continue through the cell in which the communication is currently in progress. There have been problems such as poor quality of service and poor reliability of communication.

The technique of the present invention checks the frequency environment of each cell in the base station, and registers and communicates with the terminal through the optimal cell.If the frequency environment is better by checking the frequency environment of the neighboring cell during terminal communication, the neighboring cell is better. It is an object of the present invention to provide a method for automatically selecting a cell having excellent call quality through channel registration and channel assignment and channel switching.

In order to achieve the above object, the present invention, in the wireless subscriber network system, inputs the Pencode value of the base station alpha cell to the terminal, and confirms the frequency environment of the alpha cell by the terminal and records and stores in the memory Alpha process to do; A beta process of adding a predetermined first P & P value to the alpha P & C value input in the alpha process to be a P & P value of the beta cell, checking the frequency environment of the beta cell, and recording and storing the beta cell in the memory; A gamma process of adding a predetermined second P & P value to the alpha P & P value input in the alpha process to become a P & P value of the gamma cell, checking the frequency environment of the gamma cell, and storing the same in the memory; A cell selection process of selecting cells having the best frequency environment by comparing and analyzing the values stored in the memory; An opening process of registering a terminal with the selected cell and allocating a communication channel; A communication process in which a terminal accesses and communicates through the assigned channel; A termination determination step of determining whether the terminal terminates communication; Monitoring by the terminal to confirm whether the frequency environment of the neighboring cell is better; When the frequency environment of the neighboring cell is better in the monitoring process, the terminal may be registered with the neighboring cell, and the communication channel may be allocated, and the switching channel may be switched to the assigned channel to maintain communication.

Hereinafter, a cell selection method of a wireless subscriber network (WLL) terminal according to the present invention will be described with reference to the accompanying drawings.

3 is a flowchart illustrating a cell selection of a wireless subscriber network terminal according to the present invention.

According to the attached Figure 3, the cell selection method of the wireless subscriber network terminal according to the present invention, in the wireless subscriber network (WLL) system, the terminal 30, in the area of the cell 40 of the base station 20, 31 and 32, the PN Code Base Seed value of the base station 20 alpha (α) cell is manually input by the operator, and recorded and stored in the corresponding memory area. The terminal 30, 31, 32 receives and demodulates a base station transmission signal of an alpha cell according to a code value, thereby measuring and confirming a frequency environment based on received signal strength (RSSI) and signal quality, respectively. And, the alpha process (S100) for recording and storing in the corresponding memory area of the terminal (30,31,32), respectively,

By adding a predetermined first PEN code value, for example, a 170 PN Code value to the PN code value of the alpha cell input in the alpha process (S100), the PEN of the beta (β) cell Code, and at the same time, the terminals 30, 31, and 32 receive and demodulate a signal transmitted from the beta cell of the base station 20, thereby receiving the received signal strength (RSSI) and the signal quality of the beta cell. Beta process (S110) for measuring and recording the frequency environment, and recording and storing each in the allocated memory region,

The Pencode of the gamma (γ) cell is obtained by adding a predetermined PN Code value, for example, a PN Code value of 340, to an Alpha PN Code value input in the alpha process (S100). Value, and at the same time, the terminals 30, 31, and 32 receive and demodulate the signals transmitted from the gamma cells of the base station 20, thereby receiving the received signal strength (RSSI) and the signal quality (Signal Quality) of the gamma cells. Gamma process (S120) for measuring and storing the respective frequency environments, and recording and storing each in an allocated memory area;

A cell that reads and compares the received signal strength values and the signal sensitivity values of alpha, beta, and gamma cells respectively stored in the corresponding memory areas of the terminals 30, 31, and 32, and selects and determines a cell having the best frequency environment. Selection process (S130),

By transmitting the unique number (ID) of the terminal to the cell selected by the cell selection process (S130), by checking the database (DB) of the central control unit 10 to confirm whether or not the registered terminal, in the case of a registered terminal An opening process of receiving a communication channel by the central controller 10 (S140);

A communication process (S150) in which the terminals 30, 31, and 32 are connected to the base station 20 and communicate with each other through the communication channel allocated by the opening process (S140);

End determination process (S160) for determining whether the terminal (30, 31, 32) completes the communication and ends;

Whether the frequency environment of the adjacent cell is better by the terminals 30, 31, and 32, the alpha process (S100), the beta process (S110), the gamma process (S120), and the cell selection process (S130) are repeatedly performed. By doing so, the monitoring process to check (S170),

When the frequency environment of the neighboring cell is better in the monitoring process (S170), the terminal 30, 31, 32 is registered and the corresponding communication channel is allocated to the neighboring cell through the same process as the opening process (S140). After switching to the assigned communication channel to maintain communication, the change-opening process (S180) of feeding back to the communication process (S150) is performed.

Hereinafter, a method of selecting a cell of a wireless access network terminal according to the present invention having the above configuration will be described in detail with reference to the accompanying drawings.

The wireless subscriber network (WLL) system adopts the broadband CDMA mobile communication system as it is, and at the same time, the terminals 30, 31, and 32 are fixed and used at a predetermined place. In this process, the hand-over function, which continuously allocates channels and continues communication, is removed.

Accordingly, the WLL terminal 30, 31, 32 is connected to the central controller 10 through one cell 40, and is connected and handed over to the central controller 10 through a plurality of cells 40. (Hand-over) is not available, so communication is not possible while moving.

In the present technology, the terminals 30, 31, and 32 are connected to the central control unit 10 through the multiple cells 40 of the base station 20, and the respective frequency environments are measured, and the measured values are allocated to the memory. In order to store each in the, and to connect the communication channel with a good cell 40 frequency environment.

When the terminals 30, 31, and 32 are installed and operated by a wireless subscriber network (WLL) system operator, the operator directly inputs the PN code value of an alpha (α) cell or sector of the base station by manual operation. Recorded and stored in the memory area.                     

The terminals 30, 31, and 32 receive the signal transmitted through the alpha cell of the base station 20, demodulate the received gain control (RXAGC) by using the input PN code value. By measuring the received signal strength (RSSI: Receive Signal Strength Indicator).

The lower RXAGC value means that the RSSI is larger, so that the lower the RXAGC value, the better the received signal strength (RSSI) of the signal received from the alpha cell of the base station 20.

After the RSSI value measured as described above is recorded and stored in the allocated memory of the terminal 30, 31, or 32, the terminal 30, 31, or 32 is randomly selected from a plurality of calls or channels assigned to the alpha cell. By selecting the channel, the signal quality is measured by calculating the correlation value, which identifies how much more the received and demodulated signal is related over a very short time period.

In more detail, the higher the received signal quality, the better the frequency environment.

The signal sensitivity of the alpha cell measured as described above is recorded and stored in the corresponding memory area allocated to the terminals 30, 31, and 32 (S100).

The terminal 30, 31, or 32 that has completed the above step S100 automatically adds a predetermined first PN code value, for example, a PN code value of 170, to the PN code value of the alpha cell. Thus, it is possible to receive a signal transmitted from the beta cell of the base station 20.

The first PN code value is determined by the designer of the base station 20 of the wireless subscriber network system, and may be different for each base station 20.

As described above, the terminals 30, 31, and 32, which are able to automatically receive the beta cell signal, receive the beta cell received signal strength through the same process as the method of measuring the received signal strength and signal sensitivity of the alpha cell. And the signal sensitivity is measured, and stored in each of the allocated memory area (S110).

When the received signal strength and signal sensitivity measurement of the beta cell is completed as described above, and recording and storage in the corresponding memory area are completed, the terminals 30, 31, and 32 receive the signal of the gamma cell, and the alpha cell. By automatically adding a predetermined second PN Code value, for example, a PN Code value of 340, to the PN Code value of the, it is possible to receive a signal transmitted from the gamma cell of the base station 20.

As described above, since the second PN code value is determined by the base station 20 designer, the second PN code value may be different for each base station manufacturer, and the terminal capable of automatically receiving the signal of the gamma cell as described above. 30, 31 and 32 measure the received signal strength and the signal sensitivity of the gamma cell through the same process as the method of measuring the received signal strength and the signal sensitivity of the alpha or beta cells, respectively, and allocate the corresponding memory regions. Record and store in (S120).

The terminals 30, 31, and 32 read and compare all received signal strengths and signal sensitivity values of alpha, beta, and gamma cells stored in the corresponding memory, and determine the cells having the best received signal strength and the best signal sensitivity. By selecting a cell, the cell with the best frequency environment is selected.                     

In the above process, since a cell having a good signal strength and a cell having a good signal sensitivity may be different from each other, a cell having a best frequency environment is finally selected or selected based on an appropriate criterion of a terminal corresponding program (S130). ,

The terminal 30, 31, 32 transmits the unique number (ID) of the terminal 30, 31, 32 to the central control unit 10 through the cell selected above, thereby providing a database of the central control unit 10. It is determined whether the terminal is registered in the terminal, in the case of the registered terminal (30, 31, 32), the communication channel is allocated by the central control unit 10, the terminal is assigned communication through the corresponding cell of the base station Opening by tuning to the channel (S140).

The terminal 30, 31, 32 communicates through the corresponding channel (S150), and if the communication is terminated by determining whether the communication is terminated (S160).

When the communication is not terminated in the process (S160), the terminal (30, 31, 32) monitors or confirms the frequency environment of the adjacent cell while the communication is in progress, the process, the alpha process (S100 ), The beta process (S110), the gamma process (S120) and the cell selection process (S130) is repeatedly performed (S170).

In the monitoring process (S170), if the frequency environment of the adjacent cell is not better than the frequency environment of the cell currently in communication, the feedback (Feedback) to the communication process (S150), and more than the frequency environment of the cell currently in communication If it is excellent or good, it transmits a unique number (ID) of the terminal (30, 31, 32) to the central control unit 10 through the neighboring cell, and requests to communicate through the neighboring cell, the central control unit ( 10) checks the received unique number (ID) by searching the database (DB), and checks whether the registered terminal (30,31,32), and if the unique number is confirmed to be the registered terminal, Allocating a channel capable of communicating through an adjacent cell, the terminal 30, 31, 32 receiving the channel assignment connects the communication channel through the assigned channel, and switches to the communication channel of the connected cell Excellent products In a query frequency environment, communication can be maintained.

In summary, the present invention as described above, the frequency environment where the fixed terminal (30, 31, 32) of the wireless subscriber network (WLL) is located, the alpha where one base station 20 is generated In case of overlapping by a service area by a plurality of cells of (α), beta (β), and gamma (γ), by the operator installing the terminals 30, 31, 32, the corresponding terminals 30, 31 (32) manually input the PN code of the alpha (α) cell, and the first and second PN corresponding to the difference between the PN code values of the beta (β) cell and the gamma (γ) cell by the system design. By setting and entering a code value, the terminal is recorded and stored in the terminals 30, 31, and 32, and the terminal is automatically connected to the central control unit through the adjacent cell.

Therefore, while the communication is in progress, while continuously checking or monitoring the frequency environment of the adjacent cell, it is possible to maintain a high quality communication by allocating and switching a channel to a cell having a frequency environment superior to the frequency environment of the cell where communication is currently being performed.

According to the present invention having the above configuration, in a wireless subscriber network (WLL) system using a fixed terminal wirelessly connected, when the terminal is located in an area overlapping a service area of multiple cells by one base station, Forcibly input the PN code value of the cell and input the first and second set values to automatically calculate the PN code value of the beta cell and the PN code value of the gamma cell, thereby checking and monitoring the frequency environment of the adjacent cell. As a result, the call quality can be improved by changing and opening a cell having excellent frequency environment.

Claims (8)

In the wireless subscriber network system, An alpha process of inputting the P & P value of the base station alpha cell to the terminal, checking the frequency environment of the alpha cell by the terminal, and storing the result in a corresponding memory; A beta process of adding a predetermined first P & P value to the alpha P & P value input in the alpha process to be a P & P value of the beta cell, checking the frequency environment of the beta cell, and recording and storing the beta cell in the memory; A gamma process for adding a predetermined second P & P value to the alpha P & P value input in the alpha process to become the P & P value of the gamma cell, checking the frequency environment of the gamma cell, and storing the same in the memory; The cell selection method of the wireless subscriber network terminal, characterized in that the cell selection process comprises a cell selection process for selecting the cell having the best frequency environment by comparing and analyzing the values stored in the corresponding memory. In the wireless subscriber network system, An opening process of registering a terminal and assigning a communication channel to the best selected cell by comparing and analyzing the frequency environment of each cell; A communication process of connecting and communicating with a terminal through the assigned channel; An end determination process of determining whether the terminal terminates communication; A monitoring process for checking whether the frequency environment of the neighboring cell is better by the terminal; When the frequency environment of the neighboring cell is better in the monitoring process, the terminal registers with the neighboring cell, receives the communication channel, switches to the allocated channel, maintains communication, and then returns to the communication process. Cell selection method of a wireless subscriber network terminal, characterized in that consisting of a process According to claim 1, The alpha process is recorded and stored by inputting an alpha-encoded value of an alpha cell into a corresponding memory area of the terminal by the operator, and the terminal demodulates the signal of the alpha cell to measure received signal strength and signal sensitivity, respectively, Cell selection method of a wireless subscriber network terminal, characterized in that the recording and storing in the corresponding area of each According to claim 1, In the beta process, by adding a predetermined first encoded value to the encoded value of the alpha cell input by the operator, it becomes the encoded value of the beta cell, and the terminal demodulates the signal of the beta cell and receives the received signal. The cell selection method of the wireless subscriber network terminal, characterized in that the strength and signal sensitivity are respectively measured and recorded and stored in the corresponding area of the memory. According to claim 1, In the gamma process, by adding a predetermined second encoded value to the encoded value of the alpha cell inputted by the operator, the gamma cell becomes the encoded value of the gamma cell, and the terminal demodulates the signal of the gamma cell to receive the received signal. The cell selection method of the wireless subscriber network terminal, characterized in that the strength and signal sensitivity are respectively measured and recorded and stored in the corresponding area of the memory. According to claim 1, In the cell selection process, all received signal strengths and signal sensitivity values of alpha, beta, and gamma cells stored in corresponding regions of the memory are read and compared to determine a cell having the best frequency environment. Cell selection method of subscriber network terminal The method of claim 2, In the opening process, by transmitting the unique number of the terminal to the corresponding cell, the registration request for communication to the wireless subscriber network central control unit is checked and whether the corresponding terminal is registered, and the registered terminal is assigned a communication channel. Cell selection method of wireless subscriber network terminal The method of claim 2, The monitoring process is a cell selection method of a wireless subscriber network terminal, characterized in that for repeating the alpha process, beta process, gamma process and cell selection process.

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