KR100286755B1 - Handoff Processing Method in Wireless Asynchronous Transfer Mode Switching System - Google Patents

Abstract

The present invention provides a handoff processing method for reducing handoff load by minimizing connection processing when a handoff occurs in a wireless Asynchronous Transfer Mode (ATM) switching environment. Only the connection between the terminal and the corresponding ATM switching period is reset, and the connection between the ATM switch and the other terminal is maintained as it is.In the case of handoff during the ATM switching period, the mobile ATM switch and the PVC channel of the ATM switching period are used. By performing the transmission and reception of data for handoff, the call resetting process of the ATM switching period due to the handoff is omitted, and the connection between the ATM switch and the counterpart terminal is maintained as it is. Therefore, the call processing load due to the handoff occurrence can be reduced to reduce the smooth blocking rate of the handoff call.

Description

Handoff Processing Method in Wireless Asynchronous Transfer Mode Switching System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handoff processing method in a wireless asynchronous transfer mode (hereinafter, referred to as ATM) switching system, and in particular, a hand that can reduce the load due to call resetting processing due to a handoff occurrence. It relates to an off processing method.

ATM exchange can handle a plurality of media (multimedia), such as voice and video data, and is an intermediate exchange method between circuit switching and packet switching. This ATM exchange is based on a 53-byte fixed-length cell. The cell is composed of a 5-byte header and 48-byte information containing control information such as label information of the destination and routing information.

When the switching system using the ATM switching method is applied to a wireless environment, handoff occurs as in the case of applying a conventional circuit switch or packet switch to a wireless environment. Handoff occurs when a wireless terminal moves from a cell that initiated a call to an adjacent cell, and establishes a new call between the new base station that is in charge of the area where the wireless terminal has moved and the other party in the call. It is handled in a receiving manner.

However, as the transmission speed between the base station and the wireless terminal is improved and the cell environment is changed from the macro cell base to the micro / pico cell base, the frequency of handoffs increases and the ATM switch is down or the hand is dropped. There is a problem that the off call is frequently blocked. Whenever a handoff occurs, the operation for establishing a new call is performed as described above, and as the number of handoffs increases, the work for setting up a call in the corresponding exchange increases, causing an overload on the ATM switch. Because.

The present invention has been made to solve the above-mentioned problem, and in the wireless asynchronous transmission mode switching system, a handoff that can reduce the load due to call resetting by performing only the changed portion during call resetting due to handoff occurrence. The purpose is to provide a treatment method.

In order to achieve the above object, the handoff processing method according to the present invention is performed in a wireless asynchronous transmission mode switching system environment, when the first wireless terminal and the second wireless terminal are in a call, the first wireless terminal moves to the same switch. In the handoff processing method when handoff is performed to another base station under jurisdiction, when the handoff is determined in the first wireless terminal, a new virtual path identifier (VPI) of the base station to be moved is detected and detected by the current base station. Sending a handoff request message including a virtual channel identifier (VCI) for the first wireless terminal; When the current base station receives the handoff request message, the base station analyzes the received message to determine the current handoff type, and when the determined handoff type is between base stations, the handoff request message including new virtual path identifier and virtual channel identifier information. Sending the to the exchange; If the exchange receives a handoff request message between base stations from the current base station, analyzing the virtual path identifier to identify the base station to be moved, and performing call setup processing according to the handoff of the switching period with the mobile base station; When the response signal according to the call establishment process is received from the base station to be moved, updating the routing information for the first wireless terminal with the virtual channel identifier and the new virtual path identifier of the first predetermined wireless terminal; After performing the update, the exchange sends a response message to the handoff request to the first wireless terminal via the current base station; If transmission and reception of the handoff preparation message including the virtual channel identifier of the first wireless terminal is performed between the first wireless terminal receiving the response message for the handoff request and the mobile base station, the call is reset according to the handoff of the first wireless terminal. And terminating the process.

In addition, during handoff period, handoff request message is transmitted through idle PVC channel among mobile ATM exchanger and current PVC exchange period, and new VCI is allocated from mobile ATM exchanger to move with mobile base station. When the call setup processing is completed in the ATM switching period, the connection processing between the mobile ATM switch and the current ATM switching period is performed, and the routing table in each exchange is updated.

1 is a block diagram illustrating a relationship between a wireless asynchronous transmission mode switching system for performing a method of processing handoff between base stations according to the present invention;

2 is an operation flowchart for a method for processing handoff between base stations according to the present invention;

3 is a block diagram of a relationship between a wireless asynchronous transmission mode switching system for performing a switching period handoff processing method according to the present invention;

4 is a flowchart illustrating an operation of an exchange period handoff processing method according to the present invention.

<Explanation of symbols for main parts of drawing>

101, 102, 301, 302: wireless terminals 110_1 to N, 150, 310, 340, 360: base station

120, 140, 320, 330, 350: ATM exchangers 121, 141, 321, 331, 351: processors

122, 143, 322, 333, 352: Routing tables 123, 143, 323, 332, 353: Switches

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an asynchronous transfer mode (AMT) exchange system for performing a base station control period handoff processing method according to the present invention, which is under the jurisdiction of the first base station 110_1. Under the jurisdiction of the second base station 110_2, a first wireless terminal 101 having a handoff between base stations is generated, a first ATM switch 120 and a first wireless terminal that manage the first to Nth base stations 110_1 to 110_N. Switched Virtual Line (Switched Virtual) with the first ATM exchanger 120 over the second wireless terminal 102, the base station 150 for judging the second wireless terminal 102, and the base station 150 for the call partner side of the call 101; Circuit, hereafter referred to as SVC) consists of a second ATM switch 140 is set up a call.

The first ATM exchanger 120 and the second ATM exchanger 140 each have a processor 121 and 141 for controlling all functions of the corresponding exchange, and routing tables 122 and 142 for storing the generated routing information for each call. It consists of switches 123 and 143 that provide a transmission path for the call.

2 is a flowchart illustrating a handoff processing method according to the present invention when a base station control period handoff occurs.

That is, as the first wireless terminal 101 under the jurisdiction of the first base station 110_1 moves to the cell area controlled by the second base station 110_2, the power transmitted from the second base station 110_2 is transmitted to the first base station 110_1. If greater than the power sent from the first wireless terminal 101, the first wireless terminal 101 determines the handoff in step 201. In operation 202, the virtual path identifier (hereinafter, referred to as VPI) of the second base station 110_2 that is the mobile base station whose current power is largely detected is detected.

In operation 203, the first wireless terminal 101 transmits a handoff to the first base station 110_1, which is a current base station, including a VPI detected in operation 202 and its own virtual channel identifier (hereinafter, referred to as VCI). Send request message ([New VPI, VCI]).

Accordingly, the first base station 110_1 analyzes the new VPI information included in the handoff request message received in step 204. The analysis method searches for an unshown table provided in the first base station 110_1 using the received VPI information. As a result of the search, when the received VPI is the VPI of the base station existing in the same exchange 120, the first base station 110_1 determines the type of handoff currently requested as the handoff between base stations.

If the handoff type is determined, the first base station 110_1 proceeds to step 205 to send a handoff request message between base stations to the first ATM switch 120. The handoff request message sent includes new VPI and VCI information ([New VPI, VCI]). The transmitted handoff request message is applied to the processor 121 of the first ATM switch 120.

When the handoff request message is received, the processor 121 proceeds to step 206 to analyze the new VPI information included in the received handoff request message to determine a base station to move to. If the base station to be moved is determined as the second base station 110_2, the processor 121 proceeds to step 207 and sends a handoff request message to the second base station 110_2. At this time, the handoff request message sent includes the new VPI and the VCI of the first wireless terminal 101.

When the second base station 110_2 receives the handoff request message, the second base station 110_2 checks its own bandwidth to check whether there is currently an idle channel. As a result of the check, if there is an idle channel, the process proceeds to step 209 to send a response message (ACK) to the handoff request to the first ATM switch 120.

When the response message for the handoff request is received from the second base station 110_2, the processor 121 in the first ATM switch 120 proceeds to step 210 and the routing table 122 for the first wireless terminal 101. Update the information of). Accordingly, the routing information for the first wireless terminal 101 stored in the routing table 122 stores the new VPI and its own VCI information.

In operation 211, the processor 121 transmits a response signal for the handoff request to the first base station 110_1. A new VPI and a VCI of the first wireless terminal 101 are also included in the response message that is sent. When the response message is received, the first base station 110_1 proceeds to step 212 and sends a response message for the handoff request to the first wireless terminal 101.

Upon receiving the response message, the first wireless terminal 101 transmits a handoff ready message (Ready) to the second base station 110_2 which is the base station to be moved in step 213. The ready message to be sent includes the VCI information of the first wireless terminal 101 and is transmitted. The second base station 110_2 proceeds to step 214 and checks whether the VCI included in the received preparation information and the VCI received in step 207 are the same. If the result of the check is normal, the flow proceeds to step 215 and sends a response message to the handoff preparation message to the first wireless terminal 101, and terminates the call resetting process according to the handoff occurrence.

As described above, during the call resetting process according to the handoff occurrence, a handoff request sent to the first ATM switch 120 when the idle channel does not exist as a result of the check in the second base station 110_2 in step 208. The response message is sent to 'NOK' so that the processor 121 in the first ATM switch 120 stops the call setup process for the corresponding handoff and the call is disconnected.

FIG. 1 is an exemplary view of a case where the first wireless terminal 101 is handed off while a call is set up between the wireless terminals 101 and 102 under the jurisdiction of different ATM exchangers 120 and 140, but the same ATM exchanger is shown. Even when a handoff between base stations occurs in a situation where a call between the first wireless terminal 101 and the second wireless terminal 102 is established within 120, processing is performed as shown in FIG. That is, the resetting process for the call is carried out only between the base station to be moved and the ATM exchange which has jurisdiction over the first radio terminal where the handoff has occurred.

Figure 3 is a block diagram of the relationship between the wireless asynchronous transmission mode switching system for performing the switching period handoff processing method according to the present invention, the first wireless terminal 301, the first wireless terminal 301 is generated during the switching period; ) Is the first base station 310 which is in charge of the handset before the occurrence of the first base station 310, the first ATM switch 320 which is in charge of the first base station 310, the first wireless terminal 301 and the second party is the call A second base station 340 that manages a wireless terminal 302, a second base station 302, a second base station 340 that manages a second base station 340, and which is set up by SVC with the first ATM switch 320. 330, the first wireless terminal 301 is composed of a third base station 360 which is a base station to be moved by handoff, and a third ATM switch 350 that manages the third base station 360. The first ATM switch 320 and the third ATM switch 350 are adjacent exchangers connected by a permanent virtual circuit (hereinafter, referred to as PVC).

The first to third ATM switches 320, 330, and 350 are composed of processors 321, 331, and 351, routing tables 322, 332, and 352, and switches 323, 333, and 353, respectively.

4 is a flowchart illustrating an operation of an exchange period handoff processing method according to the present invention.

Next, the exchange period handoff processing method shown in FIG. 4 will be described with reference to FIG. 3.

That is, while the first wireless terminal 301 under the jurisdiction of the first base station 310 is in communication with the second wireless terminal 302 under the jurisdiction of the second base station 340, the first wireless terminal 301 has reached the third state. When moving to the cell area of the third base station 360 under the jurisdiction of the ATM switch 350, the first wireless terminal 301 determines a handoff in step 401. In operation 402, a virtual path identifier (hereinafter, referred to as VPI) of the third base station 360, which is a mobile base station whose current power is largely detected according to the handoff occurrence, is detected.

In step 403, the first wireless terminal 301 is handed off to the first base station 310, which is the current base station, including a VPI detected in step 402 and its virtual channel identifier (hereinafter, referred to as VCI). Send request message ([New VPI, VCI]).

Accordingly, the first base station 310 analyzes the new VPI information included in the handoff request message received in step 404. The analysis method searches for an unshown table provided in the first base station 310 using the received VPI information. As a result of the search, when the received VPI is the VPI of the base station under the jurisdiction of the adjacent third ATM switch 350, the first base station 310 determines the type of handoff currently requested as the switching period handoff.

When the handoff type is determined, the first base station 310 proceeds to step 405 and detects the identifier ID of the third ATM switch 350 that is the ATM switch to move with reference to the table held by the first base station 310. In step 406, the handover request message for the exchange period is sent to the first ATM switch 320. The handoff request message sent includes the new VPI, the ID of the ATM switch and the VCI information ([New VPI, ID of the ATM switch, VCI]). The transmitted handoff request message is applied to the processor 321 of the first ATM switch 320.

When the handoff request message is received, the processor 321 proceeds to step 407 and an idle channel on the PVC channel connected to the third ATM switch 350 which is a mobile ATM switch included in the received handoff request message. Checks whether it exists. As a result of the check, if there is an idle channel, the processor 321 proceeds to step 408.

In step 408, the processor 321 sends a switch period handoff request message to the third ATM switch 350 through the idle channel described above. The message sent at this time includes the new VPI and the connection information on the current PVC (VCI and VPI of the PVC channel used).

Accordingly, the third ATM switch 350, which is the ATM switch to be moved, checks the VPI included in the message received in step 409. That is, the base station under its jurisdiction is identified using the VPI present in the received message. When the third base station 360 that is the mobile base station is identified, the processor 351 in the third ATM switch 350 proceeds to step 410 to establish a connection between the third base station 360 and the third ATM switch 350 that are the mobile base stations. A new call setup process is performed according to the handoff occurrence. At this time, the processor 351 in the third ATM switch 350 allocates a new VCI to the first wireless terminal 301 for use in the jurisdiction of the third ATM switch 350, and the allocated new VCI is assigned to the third. Is forwarded to base station 360.

When the third base station 360 receives the handoff request message as shown in FIG. 2, the third base station 360 checks whether there is an idle channel in its wireless bandwidth, and if so, requests the handoff to the third ATM switch 350. Send a response message for.

Accordingly, the processor 351 in the third ATM switch 350 recognizes that the call setup process with the third base station 360 is completed, and proceeds to step 411 to access the PVC between the first ATM switch 320. Do the processing. When the connection process is completed, in step 412, the processor 321 in the first ATM switch 320 clears the existing VCI and VPI for the first wireless terminal 301 stored in the routing table 322, The VCI and VPI of the PVC channel connected to the third ATM switch 350 are updated to be stored.

On the other hand, the processor 351 in the third ATM switch 350 newly allocates the information in the routing table 352 for the first wireless terminal 301 handed off in step 413 to the VPI of the third base station 360. The VCI updates the information in the routing table 352 so that the VCI and VPI of the PVC channel used as output information can be stored as input information, respectively.

The third ATM switch 350 then proceeds to step 414 and transmits a response signal for the handoff request to the processor 321 of the first ATM switch 320 via the connected PVC channel. The message sent at this time includes a new VPI and a new VCI ([New VPI, New VCI]).

The processor 321 in the first ATM switch 320 sends a response message to the handoff request to the first base station 310 in step 415, and the first base station 310 sends the first wireless terminal in step 416. 301 sends a response message to the handoff request. The response message sent includes the new VPI and VCI as described above.

Upon receiving the response message, the first wireless terminal 301 transmits a handoff ready message (Ready) to the third base station 360 which is the base station to be moved in step 417. The ready message sent includes the new VPI and VCI information of the first wireless terminal 301 and is transmitted. The third base station 360 proceeds to step 418 and checks whether the VCI included in the received preparation information and the VCI set in step 410 are the same. If the result of the check is the same, the process proceeds to step 419, and sends a response message to the handoff preparation message to the first wireless terminal 301, and terminates the call resetting process according to the handoff occurrence.

In the call resetting process according to the handoff as described above, when there is no idle channel as a result of checking by the third base station 360 in step 410, the third ATM switch 350 performs the first ATM switch ( The response message to the handoff request is sent to 'NOK', so that the processor 321 in the first ATM switch 320 stops the call setup process for the corresponding handoff and the call is disconnected.

3 illustrates that when a call is in progress between wireless terminals 301 and 302 accommodated in different ATM switches 320 and 330, the first wireless terminal 301 is handed off to another switch 350. Even if the first wireless terminal 301 and the second wireless terminal 302 is a terminal accommodated in the same switch 320, the first wireless terminal 301 is handed off to the third ATM switch 350 during the call. Call reset processing by handoff is performed in the same manner as shown in FIG.

As described above, the present invention is a wireless asynchronous transfer mode switching system, when the call reset due to the handoff occurs between the base station, the wireless terminal and the reset process only during the corresponding ATM exchange period, and according to the handoff occurrence of the exchange period When a call is reset, the fixed sharing line (PVC) provided in the ATM switching period implements a process of resetting the sharing of data and the ATM switching period for the mobile base station and the mobile base station. Therefore, by eliminating the unnecessary setup process when the call is reset, the load of the ATM switch or the handoff call is blocked due to the handoff can be reduced.

Claims (2)

In a wireless asynchronous transmission mode switching system environment, when the first wireless terminal and the second wireless terminal are in a call, the first wireless terminal moves and is handed off to another base station under the same exchange. In When the handoff is determined in the first wireless terminal, the virtual path identifier (VPI) of the mobile station to be detected is detected and includes the detected new virtual path identifier to the current base station and a virtual channel identifier (VCI) for the first wireless terminal. Sending a handoff request message; The current base station analyzes the received message to determine the current handoff type when the handoff request message is received, and includes the new virtual path identifier and the virtual channel identifier information when the determined handoff type is between base stations. Sending a handoff request message to the exchange; If the exchange receives a handoff request message between base stations from the current base station, analyzing the virtual path identifier to identify the mobile base station and performing a call setup process according to the handoff between the mobile base station and the switching period; Updating, by the exchange, routing information for the first wireless terminal to the virtual channel identifier and the new virtual path identifier of the first wireless terminal when a response signal according to the call establishment process is received from the mobile base station; After performing the update, the switch issuing a response message for a handoff request to the first wireless terminal via the current base station; If transmission and reception of a handoff preparation message including a virtual channel identifier of the first wireless terminal is performed between the first wireless terminal receiving the response message for the handoff request and the mobile base station, the hand of the first wireless terminal is received. And a step of terminating the call resetting process according to the off. In the wireless asynchronous transmission mode switching system environment, when the first wireless terminal and the second wireless terminal are in a call, the first wireless terminal moves and is handed off to a base station under different exchange jurisdiction. , When the handoff is determined at the first wireless terminal, the virtual path identifier (VPI) of the mobile base station is detected and the detected new virtual path identifier is included in the current base station and the virtual channel identifier (VCI) for the first wireless terminal. Sending a handoff request message; The current base station analyzes the received handoff request message to determine the current handoff type, and if the determined handoff type is an exchange period, detects an identifier of the exchange to be moved, and detects the identifier of the mobile subscriber to be detected and the new one. Sending the handoff request message including a virtual path identifier and the virtual channel identifier information to a first exchange which is in charge of the current base station; Sending a handoff request message to the second exchange through an idle channel in a fixed connection line with the second exchange corresponding to the identifier of the mobile exchange included in the received handoff request message; ; The second switch using the new virtual path identifier included in the received handoff request message to identify a base station to which the first wireless terminal is to move, and performing call setup processing between the mobile base station and the second switching period; If the call setup process is successful, the first switch and the first wireless terminal at each of the first exchange and the second exchange are performed while performing the connection process for the fixed connection line of the second exchange period. Updating the routing information for the; If the connection processing for the fixed connection line is normally performed, the second exchange message is a response message for the handoff request to the first wireless terminal via the first switch and the current base station through the connected fixed connection line. Transmitting; If transmission and reception of a handoff preparation message including the virtual channel identifier of the first wireless terminal is performed between the first wireless terminal and the mobile base station that has received the response message, the call reset according to the handoff of the first wireless terminal is performed. And a step of terminating the processing, wherein the handoff processing method is performed in a wireless asynchronous transmission mode switching system.