KR20050115707A - Method and system for calling setup in mobile communication system - Google Patents

Abstract

The present invention relates to a method for reducing call setup time in a cellular mobile communication system. Code Division Multiple Access (hereinafter referred to as CDMA) 2000 A mobile terminal in a Dormant state for a wireless Internet access environment consisting of a 1X wireless access network and a packet data serving node. When transmitting small data, the data is transmitted without setting a traffic channel.

Description

Method and system for setting up call in mobile communication system

The present invention relates to a method and system for setting up a call in a mobile communication system, and more particularly, to a call setup method and system for shortening a call setup time.

In general, a mobile communication system is a system developed mainly for providing a voice service to a user. These mobile communication systems have been able to transmit not only voice but also data such as email or video to users. Such a mobile communication system can be classified in various ways according to its communication method, and is typically referred to as Frequency Division Multiple Access (hereinafter referred to as "FDMA"). FDMA divides a given frequency band into a plurality of channels and uses a frequency channel allocated to each subscriber. The second method is Time Division Multiple Access (hereinafter referred to as "TDMA"). TDMA uses one frequency channel for multiple subscribers. Third, it is divided into Code Division Multiple Access (hereinafter referred to as CDMA) in which a plurality of subscribers use the same frequency band in the same time zone but allocate different codes for each subscriber.

Hereinafter, a description will be given of a CDMA mobile communication system which is most representative of the above-described methods. The CDMA mobile communication system has been developed in the form of supporting only voice, a method of supporting voice and relatively low data transmission rate, a method of supporting only high speed data, and a method of simultaneously providing voice and high speed data, and the like. Separated by. Among the above methods, the CDMA mobile communication system that supports only high-speed data is the first method proposed by Qualcomm of the United States, so-called "HDR (High Data Rate)", and 3GPP2 (3 Generation Partnership Project). 2) was named "CDMA 2000 1X" by the Standardization Association. In the CDMA 2000 1X network, it is difficult to efficiently transmit data, and thus data is transmitted by using a point-to-point protocol (hereinafter referred to as "PPP") of a mobile terminal.

Unlike voice, the PPP communicates with a mobile terminal through a packet data service node (hereinafter referred to as a " PDSN ").

Various states are defined between the mobile terminal and the network for data communication. Representative of such various connection states are classified into an active state, a Dormant state, and an idle state. I will explain each of these states.

First, an active mobile terminal is in a state of transmitting / receiving data with the mobile terminal through PPP configuration. The PDSN and PPP provided with the CDMA mobile communication system are set. It is possible to actually transmit / receive data with an external host connected to an internet protocol network such as the Internet or a correspondent node such as a data transmission / reception terminal (hereinafter referred to as “CN”). Thus, the state of actually transmitting / receiving data is an active state. Accordingly, the mobile terminal maintains a channel for data transmission on the base station and air, and performs rate control or power control continuously. In particular, in the non-Voice data transmission, the active state means a state in which data is transmitted through the PDSN.

Secondly, the dormant state refers to a state in which the actual air channel is terminated and a bearer is also terminated from the PDSN to the base station of the mobile terminal. However, the PDSN maintains only the PPP session of the mobile terminal for a predetermined time. Through this, the mobile terminal in which the PPP session is maintained, that is, the mobile terminal in the dormant state, may omit the PPP session setup process when requesting the data call setup. Therefore, the mobile terminal in the dormant state can quickly resume data communication with the external host CN.

Thirdly, the idle state is a state in which a channel between the mobile station and the base station is interrupted. It means that only call and ready to receive calls are detected and only the call channel is detected. In addition, the PDSN has not established a PPP session with the mobile terminal or a PPP session with the mobile terminal has been terminated.

In these mobile communication systems, a push-to-talk (PTT) service supporting group calls (Voice or / and Data) has been provided using a data communication format.

The PTT call service calls a PTT service after selecting a group or a user who wants a voice call or data among a group of colleagues or friends or a general user displayed on the terminal while the user logs in to the network. Then, this means a service capable of mutually talking through the established call path after establishing a call path by grouping 1: 1 or 1: N in a network capable of providing a PTT service.

In order to set up the PTT service, call setting must be made between transmitting and receiving mobile terminals. During the call setup process, the users of the mobile terminals do not make a call and thus wait a lot of delay time. Therefore, there is a need for a method of providing high QoS to the users by shortening the call setup time.

Accordingly, an object of the present invention is to provide a method and system for quickly establishing a call in a mobile communication system.

Another object of the present invention is to provide a method and system for quickly establishing a call in a PTT service.

Another object of the present invention is to provide a method and system for quickly establishing a call to mobile terminals in a dormant state.

In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention.

Hereinafter, a system configuration for implementing the present invention will be described with reference to the accompanying drawings. First, a protocol used in a system to which the present invention is applied will be described, and a brief description will be made about the state thereof.

In the PTT service network to which the present invention is applied, a protocol for PTT service may use a Session Initiation Protocol (SIP) for signaling and a Real time Transport Protocol (RTP) for real-time voice packet transmission. SIP is a one-to-one and server-client signaling protocol that exchanges session information required before starting a call and removes session information that is in progress when the call ends.

If there is a packet call connected to the mobile terminal, signaling messages related to the request and response of the PTT service are transmitted and received through the traffic channel. If there is no packet call connected to the mobile terminal, the mobile terminal establishes a traffic channel for the PTT call and then transmits and receives PTT signaling messages through the configured traffic channel. In order to establish a PTT call in a dormant state, a transmitting terminal must first perform a reactivation procedure.

However, when the PTT signaling messages are transmitted through the traffic channel, delays related to the request, response, call, etc. of the traffic channel are necessarily generated. The PTT service must know if the talker is ready to listen before the talker can speak, and the caller must also know that the talker will speak to him before making a call. Thus, the PTT service can reduce the inconvenience of the user only when the user presses the PTT button and the time until the call setup is short. Accordingly, a method of providing a PTT service in a wireless access network using a short data burst (hereinafter, referred to as "SDB") has been proposed.

SDB is a common channel for signaling and control between a dormant mobile terminal and a wireless access network, that is, a common channel or paging / access according to the CDMA 2000 1X Evolution Data Only (EV-DO) standard defined by 3GPP2. This refers to a technique for transmitting a limited amount of data (usually text) through a channel (paging / access channel). The SDB message service is supported in most mobile communication systems including CDMA because of the advantage of transmitting and receiving data without the burden of assigning traffic channels. The PTT signaling (request, response) message is carried on the forward and reverse common channels, and the PTT signaling message is made in SDB format. It is transmitted using a forward common control channel (F-CCCH) and a reverse extended access channel (R-EACH). The PTT terminal carries a PTT request message on a DBM (Data Burst Message) capable of fast transmission instead of a traffic channel and transmits it through a common channel. In the middle of waiting for a response to the PTT request message, an origination message or a reconnect message is transmitted in advance to set up a traffic channel for transmitting PTT voice packets.

As such, when a data transfer is required to a mobile station in a doped state such as a PTT service, SDB transmission and reception through a wireless access network should be possible. When the wireless access network delivers an IP packet to a terminal in a doped state, such as a PTT call, the wireless access network that receives a PPP frame from the PDSN transmits it to an SDB or converts the dormant mobile terminal into an active state and then traffics. You need to decide whether to send on the channel. Therefore, there is a need for a method in which the radio access network can determine to send a PPP frame to the SDB.

Then, a network configuration capable of providing a PTT service will be described with reference to the accompanying drawings.

1 is a configuration diagram of a network for providing a PTT service in a CDMA 2000 1X system to which the present invention is applied. Although each of the components shown in FIG. 1 is shown for simplicity of explanation, in practice, a plurality of network components constitute a CDMA 2000 1X network.

In the present invention, mobile stations (hereinafter referred to as "MS") 100a and 100b are mobile terminals supporting PTT service, equipped with a PTT button, and capable of wireless access according to the CDMA 2000 1X standard. In FIG. 1, a base transceiver station (hereinafter referred to as "BTS") 102a and 102b, a base station controller (hereinafter referred to as "BSC") 104a and 104b, and a packet controller (Packet) Control Function (hereinafter referred to as "PCF") (106a, 106b) will be grouped together to be called a wireless access network. The MSs 100a and 100b and the BTSs 102a and 102b are configured in a wireless network to perform communication, and the BTSs 102a and 102b provide power control and rate control to the MSs 100a and 100b. Can be directed. In FIG. 1, mobile terminals wirelessly connect to different wireless access networks to use a PTT service, but in practice, multiple terminals may wirelessly access the same wireless access network to use a PTT service. The BTSs 102a and 102b are connected to BSCs 104a and 104b that manage handoffs of the MSs 100a and 100b. One or more BTSs 102a and 102b are connected to the BSCs 104a and 104b, and the BSCs 104a and 104b control the BTSs 102a and 102b. To process non-voice packet data, the BSCs 104a and 104b are connected to a PDSN 108, which is matched through the PCFs 106a and 106b. The PDSN 108 is connected to an external IP network 110, and a PTT server unit 160 that controls a PTT service is connected to the IP network 110.

In order to provide the optimal PTT service, it is necessary to reduce the PTT call setup delay time as much as possible. For this purpose, a PTT signal message is transmitted to the SDB. SDB is a standard that allows a terminal that transitions to a dormant state to transmit data of 254 bytes or less through a signaling channel. When the PTT signal message is transmitted to the SDB, the PTT signal message can be quickly transmitted / received without the need for reactivation of doped MSs. Due to this advantage, SDB transmission is necessary to provide a PTT service.

FIG. 2 is a detailed view of the PTT server unit 160 shown in FIG. 1. First, the presence server 161 is a server that manages state information such as whether the other party is logged in on the network, and the PTT server 162 is connected to the network to manage PTT sessions and to receive voice from the sending MS. It relays the packet to the receiving MS group. The PTT MRS 163 changes the format since the vocoder is different for each MS. The SIP proxy server 165 determines whether the MS should send signaling quickly, and the operations, administrations and maintenance (OAM) 164 manages a network.

3 is a flowchart illustrating a message for performing a PTT service according to an exemplary embodiment of the present invention. 3 illustrates a procedure in which the MS 100a performs a PTT service with the MS 100b of another network, and the MS 100a that wants the PTT service is called a first MS 100a. The MS 100b receiving the PTT service from the MS 100a will be referred to as a second MS 100b. In addition, in FIG. 3, a PCF is connected between the BS and the PDSN to transmit data, which will be omitted for convenience of description.

The MS 100a in the dormant state transmits a PTT service request message (“INVITE”) to the wireless access network 120a in step 301 when a PTT service request is made. The MS 100a immediately reactivates even if there is no packet data to be sent while waiting for a response to the PTT service request message. In this case, reactivation means that the MS in a doped state reconnects a wireless channel with a wireless network. In step 302, the MS 100a reactivates to set up a traffic channel. A wireless access network that receives and transmits the PTT service request message (INVITE) of the MS 100a requesting the PTT service will be referred to as a first wireless access network 120a. In step 303, the first wireless access network 120a sends the PTT service request message to the PDSN 108, and in step 304, the SIP proxy in the PTT server unit 160 sends the PTT service request message sent through the PDSN 108. Send to server 165. In addition, in step 304, the SIP proxy server 165 routes a SIP message to the PTT server 162, and the PTT server 162 interworks with the presence server 161 and then the PTT service request message (INVITE). Retransmit to the SIP proxy server 165. At this time, the PTT server unit 160 indicates whether SDB transmission is necessary using the TOS field of the IP header (A). The process A will be described in detail with reference to Table 1 below.

In step 305, the SIP proxy server 165 transmits a PTT service request message to the PDSN 108. The wireless access network of the second MS 100b that the first MS 100a which has transmitted the PTT service request message described above wants to call through the PTT service will be referred to as a second wireless access network 120b. In step 306, the PDSN 108 transmits a PTT service request message to the second wireless access network 120b. At this time, the PDSN 108 informs the PCF 106b of the second BS that SDB transmission is necessary using a GRE header (B). The process B will also be described in detail with reference to Table 2 below.

In step 307, the PCF 106b determines whether to transmit the SDB. If it is possible to transmit to the SDB in step 307, and transmits the PTT service request message to the second MS (100b) in the SDB in step 308. In addition, when the PTT service request message is received from the second MS 100b in step 308, the second MS 100b notifies the receiver of the PTT service request by sound or other means. Upon receiving the PTT service request message in step 309, the second MS 100b transmits a PTT confirmation message ("200 OK") to the second wireless access network 120b through the SDB. In step 310, the second MS 100b performs a reactivation procedure to establish a traffic channel. In step 311, the second wireless access network 120b transmits a PTT confirmation message (“200 OK”) to the PDSN 108. In step 312, the PDSN 108 transmits the message to the SIP proxy server 165. The SIP proxy server 165 transmits the PTT confirmation message to the PTT server 162. The PTT server 162 reconnects the PTT confirmation message to the SIP proxy server 165 after interworking with the PTT MRS server 163. In step 313, the SIP proxy server 165 transmits the PTT confirmation message to the PDSN 108. In step 314, the PDSN 108 converts the PTT confirmation message into a Point to Point Protocol (PPP) frame and transmits the PTT confirmation message to the first MS 120a and the PCF 106a. In step 315, the PCF 106 determines whether to transmit the SDB. In step 316, the PCF 106a transmits the PTT acknowledgment message to the SDB if it can transmit to the SDB, and transmits the PTT confirmation message to the first MS 100a through the traffic channel if possible. In step 317, the first MS 100a receives the PTT acknowledgment message and notifies a caller that a traffic channel is established by sound or other method. In step 318, the first MS 100a transmits an acknowledgment message (ACK) in response to receiving the PTT acknowledgment message.

In the section A, the PTT server unit 160 needs to display a message for SDB transmission. In the section B, the PDSN 108 needs to inform the first and second radio access networks 120a and 120b that SDB transmission is required.

The procedure of the PDSN 108 and the PTT server unit 160 in the above-mentioned sections A and B will be described below.

First, the section A is a method for displaying a message requiring SDB transmission in the PTT server unit 160. 4 is a header format format of an Internet protocol (hereinafter referred to as IP) defined in Request For Comments (RFC) 791 issued by the Internet Engineering Task Force (IETF), and FIG. 5 is a service defined in each RFC. A diagram illustrating the bit configuration of types. 4 and 5, the procedure of the section A will be described in detail. The PTT server unit 160 uses a type of service (hereinafter referred to as TOS) field of the IP header format to indicate the type of service. The TOS field 400 is the second byte of the IP header, which is 20 bytes in length. The TOS field may be used to support quality of service (hereinafter referred to as QoS) in an enterprise network or a service provider network. RFC 791 (500) of the TOS field shown in FIG. 5 is a standard of the Internet protocol, and the TOS field defined in RFC 1349 (502) is a service type of an Internet Control Message Protocol (ICMP) message. Define the use of. And finally, it includes values for supporting the Differentiated Service Code Point (DSCP) defined in RFC 2474 (504). In the present invention, it is assumed that the PTT server unit 160 complies with RFC 791 and aims to achieve the object by using the last two bits of the 8-bit TOS field. Descriptions of the remaining fields of the IP header format are defined in each RFC and will be omitted here. The PTT server unit 160 sets a TOS field by dividing a service type as defined with the first and second wireless access networks 120a and 120b. The service division between the PTT server unit 160 and the first and second wireless access networks 120a and 120b is shown in Table 1 below.

 Service division  TOS field settings Operation method of wireless access network  Normal Service  0000 0000  The radio access network performs a network initialization reactivation procedure and transmits data through the traffic channel.  Fast service  0000 0001  Wireless access network transmits data according to SDB delivery procedure.  Implicit Service  0000 0010  The wireless access network stores data in a buffer without performing a network initialization reactivation procedure. Thereafter, when the reactivation procedure of the mobile station is completed, data is transmitted to the traffic channel.  reserved  0000 0011  not used

Next, in the section B, the PDSN 108 informs the first and second radio access networks 120a and 120b whether SDB is transmitted.

6 shows an encapsulation process performed when the PDSN 106 receives an IP datagram. First, in step 600, the PDSN 108 receives an IP packet, and in step 602, the PDSN 108 attaches a PPP header and a tail to the IP packet. Thereafter, in step 604, the packet is appended with an IP header and a GRE header before the PDSN 108 transmits the R-P interface. When the PDSN 108 receives the IP datagram transmitted from the PTT server unit 160, the MSs are distinguished using the destination address 402 included in the IP datagram. Next, the PCF address of the wireless access network to which the MS is connected is determined by referring to the packet data session information, and the IP datagram is converted into a PPP frame and transmitted to the corresponding PCF through an R-P (RadioNetwork-PDSN) tunnel. At this time, the service delimiter is displayed on the GRE (Generic Routing Encapsulation) header according to the type of service delivered to the MSs by referring to the TOS field of the IP datagram displayed by the PTT server unit 160 and transmitted to the PCF.

7 shows a GRE header format defining an interface between a PDSN and a PCF. The PDSN indicates the type of service to be delivered to the MSs using the reserved field 700 among the GRE header fields as shown in Table 2 below.

 Service division  Setting the GRE Header reserved Field  Normal Service  0000 0000  Fast service  0000 0001  Implicit Service  0000 0010  reserved  0000 0011

When receiving the IP datagram, the PCF can identify the type of service delivered to the MSs by checking the reserved field included in the GRE header, and forwards the PPP frame to the MSs according to the operation method for each service classification described in Table 1 above. To pass.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the equivalents of the claims as well as the claims to be described later.

The present invention operating as described in detail above enables efficient SDB transmission by quickly transmitting a small size of data without a procedure of allocating a traffic channel to MSs in a doped state. By enabling efficient SDB transmission, it is possible to provide a data push service or a PTT service in a mobile communication network such as a CDMA 2000 system.

1 is a diagram showing the configuration of a network for providing a PTT service in a CDMA 2000 1X system to which the present invention is applied;

2 is a view showing the PTT server unit shown in FIG.

3 is a message flow diagram for performing a PTT service according to an embodiment of the present invention;

4 illustrates a header format format of an internet protocol according to RFC 791;

5 is a diagram showing a configuration of service type bits defined in each RFC;

6 is a diagram illustrating an encapsulation process performed when a PDSN receives an Internet Protocol datagram.

7 illustrates a GRE header format defining an interface between a PDSN and a PCF.

Claims (12)

In the method for the mobile terminal of the mobile communication system to perform communication via a push-to-talk server unit, Generating a push-to-talk service request message to the mobile communication system when the mobile terminal in a dormant state is requested to communicate through the push-to-talk server unit; And reactivating after transmitting the push-to-talk service request message. The method of claim 1, wherein the reactivation process, Generating and transmitting a calling message to the mobile communication system; And establishing a traffic channel with the mobile communication system. In the method for the mobile terminal of the mobile communication system to perform communication via a push-to-talk server unit, Generating a push-to-talk confirmation message when the push-to-talk service request message is received from the mobile communication system and transmitting the generated message to the mobile communication system; And reactivating after transmitting the push-to-talk service confirmation message. The method of claim 3, wherein the reactivation process, Generating and transmitting a calling message to the mobile communication system; And establishing a traffic channel with the mobile communication system. In the mobile communication system including a wireless access network for wireless communication with at least two mobile terminals and a push-to-talk server unit for providing a push-to-talk service to the mobile terminal through a packet data service node connected to the wireless access network. In the call setup method, Generating and transmitting a push-to-talk request message when a push-to-talk service is requested by the mobile terminal in a dormant state; The wireless access network indicates whether the short data burst transmission is required in the service type field of the Internet protocol header upon receiving the push-to-talk request message and transmits the short data burst to the push-to-talk server unit through the packet data service node. Characterized in that the method. The method of claim 5, The packet data service node using a generic routing encapsulation header and transmitting a short data burst transmission to a wireless access network wirelessly communicating with a destination mobile terminal; The wireless access network further comprises the step of transmitting a push-to-talk request message to the called terminal through a short data burst message. The method of claim 6, When the push-to-talk server unit receives a push-to-talk confirmation message indicating whether push-to-talk service is available through the terminating wireless access network and a packet data service node from the terminating mobile terminal, the push-to-talk server uses the service type field of the internet protocol header. Displaying a push-to-talk confirmation message and transmitting it to the packet data service node; And the packet data service node notifies a push-to-talk service is available to a wireless access network wirelessly communicating with an originating mobile terminal using a generic routing encapsulation header. The method of claim 7, wherein And setting the last 2 bits of the 8 bits of the service type field of the internet protocol when the short data burst is transmitted. The method of claim 7, wherein And indicating that short data burst transmission is possible in the reserved field of the generic routing encapsulation header. A mobile communication system for providing a push-to-talk service to at least two mobile terminals, Transmitting a push-to-talk service request message according to the push-to-talk service request from the originating mobile terminal in a dormant state with a short data burst, and receiving a push-to-talk service confirmation message indicating whether the push-to-talk service is possible. The first wireless access network, Receives the push-to-talk service request message and the push-to-talk service confirmation message received from the called terminal, and transmits a short burst of data when the push-to-talk service request and the push-to-talk service are confirmed using the service type field of the Internet protocol header. A push-to-talk server unit which displays whether the push-to-talk service request message and the push-to-talk service confirmation message are displayed; The push-to-talk service request message indicating whether a short data burst is transmitted from the push-to-talk server unit and the push-to-talk service confirmation message indicating whether the push-to-talk service is available are shortened by using a reservation field of a generic routing encapsulation header. A packet data service node indicating whether a data burst is transmitted; The packet data service node receives a push-to-talk service request message indicating whether to transmit a short data burst and receives a push-to-talk service request through a short data burst according to the indication whether the short data burst is transmitted to the called terminal. Said system comprising: a. In the mobile terminal for the mobile terminal of the mobile communication system to communicate through a push-to-talk server unit, A push-to-talk service request message generation unit for generating a push-to-talk service request message when a push-to-talk service is requested by a user; A transmitter for transmitting the generated message; When a push-to-talk service is requested in the doment state, the control unit controls the generation of the push-to-talk service request message, and controls to reactivate the terminal after transmitting the push-to-talk service request message. The apparatus described above. In the apparatus for the mobile terminal of the mobile communication system to perform a communication through the push-to-talk server unit, A receiver configured to receive the push-to-talk service request message from the mobile communication system; A message generator for generating a push-to-talk confirmation message; A message transmitter for transmitting the generated message to the mobile communication system; Controls generation of the push-to-talk service confirmation message by controlling the message generator when receiving a push-to-talk service request message through the receiver in a doment state, and transmits the generated message through the message transmitter. And a control unit for performing reactivation after transmission.