KR101081181B1 - Method of increasing call success rate and reducing system impedance under ev-do communication network - Google Patents

Abstract

According to the present invention, there is provided a call processing method in a mobile communication system including a first subnet and a second subnet belonging to the control of one packet data serving node (PDSN). This call processing method is performed after an access terminal (AT) in the first subnet moves to the second subnet and before the session for the AT in the second subnet is restored. First, the PDSN transmits an incoming call to the first subnet. The first subnet sends a service request message based on the reception of the incoming call to the second subnet.

Dormant / idle handoff, PCF, EV-DO, PDSN, call success rate, session retrieval

Description

How to improve call success rate and reduce system load in EV-DO network {METHOD OF INCREASING CALL SUCCESS RATE AND REDUCING SYSTEM IMPEDANCE UNDER EV-DO COMMUNICATION NETWORK}

The present invention relates to a method for improving the success rate of incoming / outgoing signals of subscribers and reducing the system load in an EV-DO system. More specifically, the terminal in the subnet boundary area is an idle / dorm (Idle / The present invention relates to a method of improving the success rate of incoming / outgoing calls and reducing the load of a system in case of crossing a subnet boundary in a Dormant state.

Recently, with the rapid development of technology in the mobile communication field, it has been provided the next generation wireless multimedia service such as video and multimedia transmission using a mobile phone, and a packet data service network for packet data processing has been proposed. EV-DO mobile communication system, one of such packet data service networks, is a representative mobile communication system having a channel structure for high-speed data transmission, and provides a forward transmission speed of about 3.1 Mbps.

EV-DO system is largely composed of access terminal (AT), wireless access network and packet core network. A wireless access network includes a base transmission subsystem (BTS) for wireless communication with a terminal, a base station controller (BSC) for controlling a base station, and a packet control function for connecting a packet core network with a controller of the base station. : PCF). The PCF connects the controller of the base station and the packet core network to transfer user traffic between them, and the session management / mobility management unit (SC / MM) manages session management and mobility management for terminals. MM). Meanwhile, the packet core network includes a packet data serving node (PDSN), an access network (AN) -authentication authorization accounting (AAA), and an AAA.

A plurality of PCFs are connected to the PDSN, and each PCF manages one subnet. When a terminal belonging to one subnet initiates wireless data communication under the EV-DO system, the PCF managing the subnet assigns the terminal a unique unicast access terminal identifier (UATI) within the subnet and session information for the terminal. (A database containing terminal information determined through parameter negotiation between the terminal and the wireless access network). Because UATI and session information are managed for each subnet, when a terminal moves from one subnet ("source subnet") to another ("target subnet"), the terminal allocates a new UATI from the PCF of the target subnet. In response, the PCF of the target subnet may continuously perform communication by retrieving session information through communication with the PCF of the source subnet.

When the terminal moves from the source subnet to the target subnet, the terminal receives the subnet ID (broadcast) broadcast from the PCF of the target subnet, and recognizes that the subnet has changed. Upon recognizing the subnet change, the terminal terminates the session associated with the PCF of the source subnet, establishes a new session with the PCF of the target subnet, and reassigns the UATI. However, if there is an incoming / outgoing call attempt between the wireless network and the terminal before the terminal recognizes the new subnet (target subnet), that is, before the new session information is in the PCF of the target subnet, the call fails. do.

Specifically, in the case of an incoming call transmitted from the wireless communication network to the terminal, the PDSN transmits a paging message only to the PCF of the source subnet (in the existing wireless communication system, paging processing is possible only to an area where session and mobility are managed). Since the paging message is transmitted only to the PCF of the source subnet), the terminal cannot receive the paging message transmitted by the PDSN because it is located in the target subnet area away from the source subnet area. In addition, considering the case where the terminal originated the call before the target subnet was recognized, the call includes UATI and session information allocated from the PCF of the source subnet, and the PCF of the target subnet manages session information for the terminal. Because it is not doing so, it closes the outgoing call (session close) and fails. Therefore, when a terminal moves from one subnet to another, if an incoming / outgoing call occurs before it recognizes the new subnet, the call is sent / received based on the session and UATI associated with the previous subnet (source subnet). However, there is a problem that the target subnet cannot properly handle the call.

Meanwhile, as described above, when the terminal moves to a new subnet, the UE receives reallocation of the UATI, and the PCF of the target subnet performs a procedure of recovering the session from the PCF of the source subnet. The load on the PCF of the target subnet and source subnet is increased. Particularly, in the area with many subscribers, the subnet area is set small in consideration of the capacity of the system. When the subnet area is small, the movement of the terminal across the subnet area is relatively frequent, so the load on the PCF of the relevant subnet is accordingly increased. There is a problem that increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art. When a subscriber at a subnet boundary moves a subnet boundary to an idle / doment state, the call is successfully performed even before the UATI request procedure according to the changed subnet recognition is performed. The present invention provides a method for reducing the load on the system by performing a session recovery procedure only when an originating call or an incoming call occurs.

According to an aspect of the present invention, there is provided a call processing method in a mobile communication system including a first subnet and a second subnet belonging to the control of one packet data serving node (PDSN). This call processing method is performed after an access terminal (AT) in the first subnet moves to the second subnet and before the session for the AT in the second subnet is restored. First, the PDSN transmits an incoming call to the first subnet. The first subnet sends a service request message based on the reception of the incoming call to the second subnet.

According to an embodiment of the present invention, the first and second subnets include first and second packet control functions (PCFs) and first and second base station controllers (BSCs), respectively. The terminal moves from a cell controlled by the first BSC of the first subnet to a cell controlled by the second BSC of the second subnet. The PDSN forwards the incoming call to the first PCF, and the received first PCF forwards the incoming call to the first BSC. The step of transmitting, by the first subnet, the service request message based on the reception of the incoming call to the second subnet includes the first PCF receiving the incoming call transmitting the service request message to the second PCF.

According to an embodiment of the present invention, the service request message includes an A13 paging request message.

According to an embodiment of the present invention, the transmission of the service request message is performed through the IP cloud.

According to an embodiment of the present invention, the second PCF receiving the service request message transmits a paging message to the AT through the second BSC.

According to an embodiment of the present invention, the first PCF forwarding the incoming call to the first BSC and the first PCF sending the service request message to the second PCF are performed simultaneously.

According to an embodiment of the present invention, the first subnet and the second subnet have different subnet IDs and color codes.

According to an embodiment of the present invention, the first subnet and the second subnet have the same subnet ID and have different color codes from each other.

According to an embodiment of the present invention, the mobile communication system is an EV-DO system.

According to an embodiment of the present invention, the second BSC controls the IP Base Transmission Subsystem (IP-BTS).

According to an aspect of the present invention, in a mobile communication system including first and second subnet regions associated with first and second color codes, respectively, when the AT moves from the first subnet to the second subnet, A method is provided for handling a call that a subnet receives from an AT. First, the second subnet receives a connection request message containing a first color code from the AT. Next, the second subnet determines whether the first color code of the access request message matches the second color code of the second subnet, and if it is determined that the first and second color codes do not match, recover the session to the first subnet. Send the request message.

In accordance with one embodiment of the present invention, the AT idles / offers handoff from the first subnet area to the second subnet area.

According to one embodiment of the invention, the first and second subnet regions have the same subnet ID.

According to the embodiments of the present invention, when a subscriber at a subnet boundary moves a subnet boundary to an idle / doment state, even if a UATI request procedure according to the changed subnet recognition is performed, the PDSN may be sourced through the Inter PCF paging scheme. By sending a paging message on both the subnet and the target subnet, the subscriber can successfully receive the call. In addition, the subscriber can reduce the load on the PCF of the target and source subnet by performing the session recovery procedure only when an outgoing call or an incoming call occurs, and the session recovery procedure is not performed in the idle / dormant state.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following, when it is determined that there is a risk of unnecessarily obscuring the gist of the present invention, a detailed description of already known functions and configurations will be omitted. In addition, it should be understood that the following description relates to one embodiment of the present invention, but the present invention is not limited thereto.

1 is a diagram schematically illustrating an EV-DO mobile communication system according to an embodiment of the present invention. As shown, the EV-DO mobile communication system is largely an access terminal (AT) 110a to 110h, a base transmission subsystem (BTS) 108a to 108h, a base station controller (BSC) 106a to 106d), a Packet Control Function (PCF) 104a and 104b, and a Packet Data Serving Node (PDSN) 102.

The ATs 110a through 110h respectively receive calls from or make calls to the BTSs 108a through 108h and BTSs 108a through 108h through the reverse and forward wireless links with the BTSs 108a through 108h that manage their areas. Send. When the ATs 110a to 110h attempt to start communication in the cell to which they belong, they first request UATI, which is a unique identifier, to the PCFs 104a and 104b and perform session negotiation with the PCFs 104a and 104b. In FIG. 1, for convenience, one AT is shown in a cell that is in charge of one BTS. However, it will be apparent to those skilled in the art that a plurality of ATs may exist in one cell.

The BTSs 108a to 108h include BTS Signaling Processors (BSPs) to process calls made and received by the BTS and perform OAM. BTSs 108a through 108h are connected to corresponding BSCs 106a through 106d, respectively.

The BSCs 106a to 106d perform resource allocation, call control, handoff control, voice and packet processing, and the like on the BTSs 108a to 108h connected thereto. The BSCs 106a to 106d receive calls from the Call & Common Control Processor (CCP) and the plurality of managed BTSs 108a to 108h to perform call processing and OAM processing that are originated / received. It includes a selection processor (SLP) for the selection of the selected frame and the Radio Link Protocol (RLP) processing. 1 shows that 64 BSTs are connected to one BSC, but according to another embodiment of the present invention, more or fewer BSTs may be connected.

In addition, BSCs 106a through 106d are connected to PCFs 1 and 2 104a and 104b, respectively, which provide interfaces between BSCs 106a through 106d and PDSN 102. PCFs 1 and 2 104a and 104b are also responsible for the traffic forwarding function, and are responsible for session management and mobility management for mobile terminals. PCFs 1 and 2 104a and 104b are connected to PDSN 102 to receive packet data from PDSN 102, govern subnets 112a and 112b, respectively, and have their own subnet ID and color code. Holds). Although FIG. 1 shows that two PCFs 104a and 104b are connected to the PDSN 102 for convenience, a larger number of PCFs may be connected to the PDSN according to another embodiment of the present invention.

PCFs 1 and 2 104a and 104b are packet control processors (PCPs) and packets that process packet data calls, manage session and mobility for ATs, and perform operation, administration, and maintenance (OAM) processing. It includes a packet interface processor (PIP) for handling the traffic of the data. Specifically, the PCP embedded in PCF 1 104a manages session information for ATs 110a, 110b, 110c, and 110d, and the PCP embedded in PCF 2 104b includes ATs 110e, 110f, 110g, and 110h. Session information).

In FIG. 1, it may be assumed that the AT 110d is handed off from the area of the BTS 108e to the area of the BTS 108e in the idle / dock state. When idle / dock handoff is made, AT 110d is assigned a new UATI from PCF 2 104b, and PCF 2 104b of target subnet 112b is assigned to PCF 1 104a of source subnet 112a. Retrieval of the session from Accordingly, the AT 110d moving to the target subnet 112b area can communicate with the PDSN 102 through the BTS 108e, the BSC 106c, and the PCF 2 104b. However, if the PDSN 102 transmits packet data to the AT 110d after the AT 110d moves to the target subnet 112b and before the UATI allocation procedure and session recovery is completed, the call may be treated as a failure. . In addition, as described below with reference to FIG. 3, a call transmitted to the AT 110d in a state in which session recovery is not performed because the AT is not aware of a subnet change may be failed. In order to solve this problem, according to an embodiment of the present invention, the call is successfully processed using the Inter PCF paging technique. Hereinafter, the Inter PCF paging technique will be described with reference to FIG. 2.

FIG. 2 is a diagram illustrating a process of transmitting a paging message to both a source subnet and a target subnet in a PDSN using an inter PCF paging scheme when receiving an incoming call.

First, PDSN 102 transmits packet data to PIP 202a in PCF 1 104a of source subnet 112a (S402). Upon receiving the packet data, the PIP 202a transmits, to the PCP 204a, BufDataInd, an indicator indicating that there is data to be transmitted to the AT (S404). The PCP 204a transmits a BufDataRsp in response to the reception of the BufDataInd to the PIP 202a, and transmits a service request (ServiceReq) message to the CCP 206a in the BSC 106b (S406). Receiving the ServiceReq message, the CCP 206a transmits a paging message to the AT via the BSP 210a in the BTS 108d (S408), and sends a ServiceRsp message including the success or failure of paging message delivery to the PCP 204a. Transmit (S410). According to an embodiment of the present invention, since the AT 110d is located outside the source subnet 112a area and in the target subnet 112b area, whether or not to transmit paging message appears as a failure.

Meanwhile, the PCP 204a transmits an A13 Paging Request message to PCPs in neighboring subnets through the IP cloud (S412). In FIG. 2, the step S412 of transmitting the A13 paging request message is shown after the step S406 of transmitting the service request message. However, according to another embodiment of the present invention, the two steps may be performed simultaneously or in sequence. It can be changed and proceed. A13 paging is a standard interface specification name that allows paging between a plurality of PCFs, and may use this to transmit paging messages between different subnets. For example, PCP 204a of source subnet 112a may send an A13 paging request message to PCP 204b of target subnet 112b. In FIG. 2, for convenience, the A13 paging request message is transmitted to one PCP 204b. However, when there are a plurality of subnets adjacent to the source subnet, the A13 paging request message is transmitted to the PCPs in the plurality of subnets. can do.

Upon receiving the A13 paging request message, the PCP 204b transmits a ServiceReq message to the CCP 206b similarly to step 406 (S414). Receiving the ServiceReq, the CCP 206b transmits a paging message to the AT via the BSP 210b in the BTS 108e (S416), and transmits to the PCP 204b including the success or failure of the paging message delivery in the ServiceRsp message. (S418). According to an embodiment of the present invention, since the terminal 110d is located outside the source subnet 112a area in the target subnet 112b area, whether or not to transmit the paging message is represented as success. Upon receiving the ServiceRsp message, the PCP 204b transmits an A13 Paging Request Ack message to the PCP 204a of the source subnet 112a (S420). As such, since the PDSN 102 delivers the paging message through the PCP 204a of the source subnet and the PCP 204b of the target subnet, even if the AT moves to a target subnet region where no session for that AT exists. The call can be received by.

3 is a diagram illustrating a case where an AT passes through a region where an IP-BTS is installed according to an embodiment of the present invention. In general, since IP-BTS is installed in a hot spot and serves a small area for increasing capacity, a cell in which an IP-BTS is in charge is surrounded by cells in charge of several BTSs belonging to different subnets.

As shown, the PCSN 1 104a and PCF 2 104b are connected to the PDSN 102, and the PCF 1 104a and PCF 2 104b manage their own subnets, respectively. According to an embodiment of the present invention, the subnet ID of the subnet managed by PCF 1 104a is set to 0x61, the color code is set to 0x61, and the subnet ID of the subnet managed by PCF 2 104b is 0x61. Is set to 0x62. According to one embodiment of the invention, the BSC 106a connected to the PCF 1 104a controls four BTSs 108a, 108b, 108c, 108d, each BTS having its own cell 502, 504, 506, 508). On the other hand, the BSC 106b connected to the PCF 2 104b manages a plurality of IP-BTSs, one of which is an IP-BTS 108e, which is a cell surrounded by four BTSs 108a, 108b, 108c, and 108d. 510).

As shown, the BTS 108d passes through the cell 510 in which the IP-BTS 108e is responsible for the cell 502 in charge of the BTS 108b while the AT 110 remains idle / docked. Moves to the cell 508 that is responsible for doing so, it crosses the boundary of the subnet twice, but because there is no change in the subnet ID (no change to 0x61), the AT 110 does not recognize the subnet zone change and therefore session recovery. Do not do it. Specifically, when the AT 110 moves from the cell 502 to the cell 510, the AT 110 receives the subnet ID (0x61) broadcast from the PCF 2 104b. Since it is determined that there is no difference from the subnet ID (0x61) that was broadcasted from 104a, it is not aware that the subnet area has changed and therefore, session recovery between PCF 2 104b and PCF 1 104a is not performed. Since session recovery is likewise not performed when the AT 110 moves from cell 510 to cell 508, the load on PCF 2 104b and PCF 1 104a is reduced.

In addition, as shown, when the AT 110 is moved from the cell 502 to the cell 508 in an idle / dock state, the session recovery procedure is not necessary in the middle, and the AT 110 is connected to the PCF 1 ( Since it returns to the subnet area managed by 104a), even if an incoming / outgoing call occurs while the AT 110 moves to the cell 508, a new UATI setup and session recovery procedure are not necessary. That is, since the AT 110 can perform communication using existing UATI and session information, there is no need for an additional UATI setup and session recovery procedure. In general, the AT is much longer in idle / dimmer (non-service standby) than in active (incoming / outgoing call), so if the AT is active when a handoff occurs Only by performing the session recovery procedure can the load on the PCF be reduced. That is, even if a handoff occurs to the AT, when the AT is in an idle / dock state, the session recovery is performed only when the AT is in an active state (an incoming / outgoing call occurs). Can be reduced.

If an incoming call is generated to the AT without performing session recovery after the handoff, the AT may successfully receive a call from the PDSN through the Inter PCF Paging technique described with reference to FIG. 2. On the other hand, the process in the case that the AT is sending a signal in the state that does not perform the session recovery after the handoff will be described with reference to FIG.

4 is a signal processing flowchart when an outgoing signal is generated from the AT. The following description will be based on the case where the AT 110 moves from the cell 502 of FIG. 3 to the cell 510 and a handoff is made. First, AT 110 transmits a connection request message to BSC 106b (S602). This message contains the UATI used while the AT 110 was located in the cell 502, which contains a color code with a value of 0x61. If the BSC 106b detects a color code of the message received from the AT 110 and determines that the color code is a color code of another subnet, the BSC 106b transmits a previous session request message to the PCF 2 104b (S604). . Specifically, according to an embodiment of the present invention, since the color code of the subnet to which the BSC 106b belongs is 0x62 and the color code of the message received from the AT 110 is 0x61, the BSC 106b is determined by the AT 110. It determines that it has moved from another subnet area and sends a previous session request message to PCF2 104b.

PCF 2 (104b) receiving the previous session request message transmits an A13 Session Information Request (A13 Session Information Request) message to PCF 1 (104a) of the source subnet (S606). In response to the A13 session information request message, PCF 1 104a transmits an A13 Session Information Response (A13 Session Information Response) message including a previous Session State Information Record (SSIR) to PCF 2 104b (S608). Having received the A13 session information response message, PCF 2 104b sends an A13 Session Information Confirm message to PCF 1 104a indicating that session recovery is completed (S610). In addition, PCF 2 104b transmits a PriorSessionRequest message to the BSC 106b in response to the previous session request message of step 604 (S612).

The BSC 106b then sends a request message of the UATI to identify the AT 110 to PCF 2 104b (S614), and PCF 2 104b grants AT 110 the only UATI in the target subnet. (S616). The BSC 106b also transmits a traffic channel assignment message to the AT 110 (S618). Although FIG. 4 shows that step 618 is performed after step 616, in accordance with another embodiment of the present invention, the two steps may be performed in a reversed order or at the same time. As such, even if an outgoing call is generated from the AT without performing session recovery after the handoff, the outgoing call is successfully processed.

As described above, one embodiment of the present invention for understanding the present invention has been described, but as will be appreciated by those skilled in the art, the present invention is not limited to the examples described herein but is not limited to the scope of the present invention. It can be variously modified, reconfigured and replaced. Accordingly, all modifications and changes that fall within the true spirit and scope of the present invention are intended to be covered by the claims.

1 is a diagram schematically illustrating an EV-DO mobile communication system according to an embodiment of the present invention.

2 is a diagram illustrating a process of transmitting a paging message to both a source subnet and a target subnet in a PDSN using an inter PCF paging technique.

3 is a diagram illustrating a case where an AT passes through a region where an IP-BTS is installed according to an embodiment of the present invention.

4 is a signal processing flowchart when an outgoing signal is generated from the AT.

<Description of Symbols for Main Parts of Drawings>

102: PDSN

104: packet control function unit (PCF)

106: base station controller (BSC)

108: base station (BTS)

110: terminal (AT)

Claims (13)

Call processing method in a mobile communication system including a first subnet and a second subnet belonging to the control of one Packet Data Serving Node (PDSN)-The method includes an access terminal: Performed after the AT) moves to the second subnet and before the session for the AT is recovered in the second subnet; The PDSN sending an incoming call to the first subnet; And Sending, by the first subnet, a service request message based on the reception of the incoming call to the second subnet; Call processing method comprising a. The method of claim 1, The first subnet includes a first packet control function (PCF) and a first base station controller (BSC), the second subnet includes a second PCF and a second BSC, The AT moves from a cell controlled by the first BSC of the first subnet to a cell controlled by the second BSC of the second subnet, The PDSN sending the incoming call to the first subnet The PDSN forwarding the incoming call to the first PCF; And The first PCF forwarding the incoming call to the first BSC Including, The transmitting of the service request message based on the reception of the incoming call to the second subnet by the first subnet includes transmitting the service request message to the second PCF by the first PCF receiving the incoming call. Call processing method. The method of claim 1, And the service request message comprises an A13 paging request message. The method of claim 1, Sending the service request message is a call processing method, characterized in that performed via the IP cloud (cloud). 3. The method of claim 2, The second PCF receiving the service request message transmits a paging message to the AT through the second BSC. 3. The method of claim 2, The step in which the first PCF forwards the incoming call to the first BSC and the step in which the first PCF sends the service request message to the second PCF are performed simultaneously. . The method of claim 1, And the first subnet and the second subnet have different subnet IDs and different color codes. The method of claim 1, And the first subnet and the second subnet have the same subnet ID and have different color codes from each other. The method of claim 1, And the mobile communication system is an EV-DO system. 3. The method of claim 2, The second BSC is a call processing method, characterized in that for controlling the IP Base Transmission Subsystem (IP-BTS). When the call is received by the AT without performing session recovery after the handoff, the incoming call is processed through the call processing method of claim 1, and when the AT sends the call without performing session recovery after the handoff. Process outgoing calls through the following call processing methods, The method for processing an outgoing call may include processing a call received by the second subnet from the AT when the AT moves from the first subnet area to the second subnet area in the mobile communication system. Associated with the first and second color codes, respectively, Receiving a connection request message including the first color code from the AT; Determining whether a first color code of the access request message matches a second color code of the second subnet; And If it is determined that the first and second color codes do not match, transmitting a session recovery request message to the first subnet. Call processing method comprising a. The method of claim 11, And the AT idles / offers handoff from the first subnet area to the second subnet area. The method of claim 11, And said first and second subnet regions have the same subnet ID.

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