KR20090035158A - Apparatus and method for multicast and broadcast service in wireless communication system - Google Patents

Abstract

An apparatus for the MBS(Multicast and Broadcast Service) and a method thereof are provided to enable a terminal which receives only the MBS to receive the broadcast without disconnection when moving between base stations within the same broadcasting zone. Synchronization of each frequency is obtained(402). Whether the DL-MAP, UL-MAP, DCD and UCD are together obtained(414). If a service request is received, the authentication of a terminal through the MBS-related pre-authentication procedure and authentication available period are confirmed(428). The terminal determines whether broadcast list information of the current time slot is received(434). The broadcast list information is received(436). If the reception is completed, a broadcast service to be received is selected on the broadcast list(438).

Description

Apparatus and method for multicast and broadcast service in mobile communication system {APPARATUS AND METHOD FOR MULTICAST AND BROADCAST SERVICE IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to an apparatus and a method for a multicast and broadcast service (MBS) in a mobile communication system, and more particularly, to an apparatus and a method for simultaneously providing an MBS and a unicast service in a mobile communication system. will be.

In general, communication systems have been developed mainly for voice services, and are gradually developing into communication systems capable of not only voice but also data services and various multimedia services. However, the voice-oriented communication system has not been able to meet the rapidly increasing service needs of users because of the relatively small transmission bandwidth and high usage fee. In addition, due to the development of the communication industry and increasing user demand for Internet services, there is an increasing need for a communication system capable of efficiently providing Internet services. As a result, it has been introduced into a mobile communication system for efficiently providing Internet services with broadband enough to meet the increasing demand of users.

The mobile communication system is a system for integrating and supporting not only voice but also various low speed and high speed data services and multimedia application services such as high definition video. These mobile communication systems are based on wireless media using broadband such as 2 GHz, 5 GHz, 26 GHz and 60 GHz, in a mobile or fixed environment. Public Switched Telephone Network (PSTN), Public Switched Data Network (PSDN), Internet Network, IMT2000 Network, ATM (Asynchronous Transfer Mode) It is a wireless communication system that can connect a network or the like and can support a channel transfer rate of 2Mbps or more. The mobile communication system may be classified into a broadband wireless subscriber network, a broadband mobile access network, and a high-speed wireless local area network (LAN) according to the mobility (fixed or mobile) of a terminal, a communication environment (indoor or outdoor), and a channel rate.

The mobile communication system is being standardized by the IEEE 802.16 standardization group of the Institute of Electrical and Electronics Engineers, one of the international standardization organizations.

Compared to the wireless technology for the conventional voice service, the IEEE 802.16 standard has a wider bandwidth of data, which allows a large amount of data to be transmitted in a short time, and enables all users to efficiently use the channel by sharing a channel (or resource). . In addition, quality of service (QoS) is guaranteed so that users can receive different quality services according to the characteristics of the service.

The main services of the mobile communication system include the Internet, Voice over IP (VoIP), and non-real time streaming services. Recently, MBS (Multicast and Broadcast Service), a real-time broadcasting service, is emerging as a new service. The MBS has the advantage of serving more channels simultaneously while supporting mobility, such as terrestrial digital multimedia broadcasting (DMB).

When the mobile communication system provides the MBS, a subscriber using only the unicast service and a subscriber receiving only the MBS may exist together. However, when there is a terminal that is in an active mode (awake mode or active mode) even when receiving only MBS, a problem arises in that the capacity of a subscriber that can be accommodated in the system is applied. In addition, when the MBS receiving terminal in an active state moves to another base station, the broadcast may be interrupted due to handover. Specifically, it is as follows.

1 illustrates a state transition diagram of a terminal in a mobile communication system.

As shown, the state of the terminal is a null state 101, a downlink channel scan state 102, a synchronization state 103, a ranging state 104 , A negotiation state 105, a registration state 106, a normal state 107, a sleep state 108, and an idle state (109). State transition of the terminal described below is performed in the base station as well as the terminal.

Referring to FIG. 1, first, the null state 101 indicates a state in which the power of the terminal is turned off. When the power of the terminal is turned on, the terminal goes to the state 102 for searching for the downlink channel after the MAC S / W initialization process.

Thereafter, the terminal attempts to acquire synchronization sequentially from the items having the largest Receive Signal Strength Indicator (RSSI) value among the frequency items, and transitions to the synchronization state 103 when the acquisition is successful.

After the UE 103 transitions to the synchronization state 103, the UE continuously monitors DL-MAP, UL-MAP, Downlink Channel Descriptor (DCD), and Uplink Channel Descriptor (UCD) messages while monitoring system information. Update When the user wants to start the Internet service, the terminal transitions to the normal state through the network entry process of the ranging state 104, the negotiation state 105, and the registration state 106 (107). do. After the terminal transitions to the normal state 107, if the user's traffic does not occur for a predetermined time, the terminal transitions to the sleep state 108 or the idle state 109 to efficiently manage the terminal power consumption. After transitioning to 108, the terminal checks for traffic until the idle timer expires. If the traffic is detected, the terminal transitions back to the normal state 107 and transmits and receives traffic. Here, the presence or absence of traffic can be inspected by receiving a TRF-IND (Traffic Indication) message sent by the system during the listening period of the sleep state.

If there is no traffic until the idle timer expires, the terminal transitions to the normal state 107, exchanges a predetermined message with the base station, and then transitions to the idle state 109. That is, the terminal transitions to the normal state 107, releases the connection with the base station, and transitions to the idle state 109. The idle state 109 indicates a state in which a wireless section connection is released but service flow (SF) information is maintained. After the transition to the idle state 109, the terminal checks whether there is incoming traffic at a predetermined time period. At this time, when the incoming traffic is detected, the terminal transitions back to the normal state 107 and transmits and receives traffic. Here, the presence or absence of traffic can be inspected by receiving a PAG-ADV (Paging Advertizement) message sent by the system during the listening period of the idle state.

As described above, according to the standard, the sleep timer (optional) and the idle timer (mandatory) manage both the system (base station) and the terminal, and when the timer expires on one side, it requests a state transition to the other side, and the other party grants approval. In response, both transition to the same state. If the other party cannot approve the status transition, he or she remains in the previous state. In addition, when transitioning from the sleep state to the idle state, the state necessarily transitions through the active state to the idle state. In addition, if an error occurs during the transition for some reason, the transition to the null state.

Based on the IEEE 802.16 standard, the state (state) of the terminal receiving the MBS service in the mobile communication network should always operate in the normal state (107).

As described above, according to the related art, the terminal receiving the MBS should always operate in the normal state 107. In general, at least one frame of content is transmitted every 256 frames (1.28 sec) in the case of MBS, and especially in case of a broadcast channel of 64 Kbps or more, which is currently targeted, the transmission interval should be much shorter. You cannot transition to sleep. As such, problems caused by the MBS terminal always operating in the active state are as follows.

First, restrictions may be placed on the capacity of subscribers acceptable in the system. In general, the mobile communication system limits the maximum number of active terminals that can be accommodated due to the limitation of the allocation of the CQI channel (CQICH). Since the terminal receiving only the MBS receives the broadcast content through a predetermined resource, that is, since resource scheduling is not necessary, it is not necessary to allocate a CQI channel. However, according to the related art, since the terminals receiving only the MBS also operate in the active state, the number of the active terminals may be saturated due to the terminals receiving only the MBS. For example, when a new terminal attempts to connect, a problem may occur in that the connection is denied due to terminals receiving only MBS, although the system may accommodate the new terminal. In addition, a user who fails to enter the normal state despite the broadcast service may not receive the broadcast service.

Second, when a terminal receiving only MBS broadcast moves between base stations, a handover procedure is performed even though no handover is required. In other words, air resources are wasted due to the handover procedure, and in the worst case, an initial network entry procedure may be performed when the handover fails, thereby causing broadcast reception to be interrupted.

As described above, operation of the terminal receiving only the MBS in an active state causes various problems.

An object of the present invention is to provide a state transition diagram of a terminal considering MBS in a mobile communication system.

Another object of the present invention is to provide an apparatus and method for simultaneously providing MBS and unicast service in a mobile communication system.

Another object of the present invention is to provide an apparatus and method for seamlessly receiving a broadcast when a terminal receiving only an MBS in a mobile communication system moves between base stations in the same broadcast zone.

It is still another object of the present invention to provide an apparatus and method for preventing saturation of an acceptable subscriber capacity due to terminals receiving only MBS in a mobile communication system.

According to a first aspect for achieving the object of the present invention, a method of operating a terminal in a mobile communication system providing a broadcast service, the process of acquiring synchronization by frequency and receiving information necessary for a broadcast service through pre-authentication. And receiving a broadcast service in a synchronized state.

According to a second aspect for achieving the object of the present invention, in the mobile communication system for providing a broadcast service means for acquiring synchronization by frequency in the apparatus of the terminal and means for receiving information necessary for the broadcast service through pre-authentication; And means for receiving a broadcast service in a synchronous state.

As described above, according to the present invention, in a mixed environment of a terminal receiving a unicast service and a terminal receiving a multicast / broadcast service (MBS), when the terminal receives only the MBS, another state other than the normal state is obtained through pre-authentication. Is characterized by receiving a broadcast service. That is, the present invention proposes a broadcast service providing method of an optimized communication system that can utilize 100% of resources provided by the system without being limited by the capacity of an acceptable subscriber due to channel allocation limitation.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. 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. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, the present invention will be described with respect to a terminal state operation method considering the Multicast and Broadcast Service (MBS) in a mobile communication system. The present invention operates in a synchronous state without transitioning to a normal state when the terminal receives only MBS in an environment where a terminal receiving a unicast service and a terminal receiving a multicast / broadcast service (MBS) are mixed. That is, since the terminal receiving only the MBS is not classified in the normal state from the system side, it is possible to prevent the normal number of subscribers from being saturated due to the terminals receiving only the MBS. In addition, since the terminal operates in a virtual idle state, the terminal does not perform an active handover procedure even when the UE moves between base stations in the same broadcast zone. In other words, it is possible to prevent radio resource waste and broadcast interruption that may occur by performing a handover procedure.

In the following description, the base station may be, for example, a radio access station (RAS) or a base station (BS). In addition, the base station controller may be an access control router (ACR) or an access service network gateway (ASN-GW). Here, the ASN-GW may perform a router function as well as a base station controller function.

2 illustrates a network structure for providing an MBS according to an embodiment of the present invention.

As shown, the network includes a content server 210, a core network 220, a wireless access network 230, and a terminal 240. Here, the core network 220 includes a policy server 221 and an MBS controller 223. The radio access network 230 includes a base station controller (ACR) and a base station (RAS) 233.

Referring to FIG. 2, first, the content server 210 generates and stores content, and provides the corresponding content to the MBS controller 223 at the request of the MBS controller 223.

The policy server 221 manages Quality of Service (QoS) information for each Internet Protocol (IP) flow. When the MBS is triggered for a specific terminal, the policy server 221 transmits a base station through a Computer Oracle and Password System (COPS) interface. Deliver triggering information to the system (ACR and RAS). Since the detailed operation of the policy server 221 is not directly related to the present invention, a detailed description thereof will be omitted.

The MBS controller 223 notifies the policy server 221 when a service request is received from the terminal 240. In addition, the MBS controller 223 receives the corresponding broadcast content (or broadcast traffic) from the content server 210 according to the broadcast schedule and transmits it to the terminal 240 through the base station controller 231 and the base station 233. .

The base station controller 231 transmits the broadcast content from the MBS controller 223 to the base station 233. Here, the base station controller 231 manages the connection and mobility of the terminal 240, and unique service flow (SF) for each uplink and downlink connection. Create For example, when the MBS triggering for the terminal 240 is notified from the policy server 221, necessary information is lowered to the terminal 240 so that the corresponding service flow can be received.

The base station 233 transmits the broadcast content from the base station controller 231 to the terminal 240. Here, the base station 233 is connected to the base station controller 231 by wire and wirelessly connected to the terminal 240. The base station 233 allocates resources to the terminal 240 by performing scheduling based on MAC (Media Access Control) layer QoS for unicast traffic. In addition, the base station 233 is time stamped and packetized from the base station controller 231 or the MBS controller 223 according to air scheduling information set by an operator for MBS traffic. ) Receives the traffic, and bypasses and broadcasts the received traffic at a time stamped time.

3 shows a scenario for MBS pre-authentication required for the UE to receive MBS service.

In order to solve the above-mentioned problems of the prior art, the following prerequisites are required for the terminal to receive the MBS service in a synchronous state. Currently, in the scheme defined in IEEE 802.16e, in order to receive MBS service, MBS_ZONE_ID and MCID information are transmitted from the system through the Dynamic Service Addition (DSA) process while the UE performs a network entry process. It is allocated and used to decode MBS bursts. When the terminal receives the MBS_ZONE_ID and the MCID through the DSA, the normal number is always maintained whenever the MBS channel is created and changed, thereby limiting the number of subscribers in the system. In order to be able to receive the MBS service even in the above situation in the synchronous state or the idle state, the UE should be able to allocate the above resources without the DSA procedure. As a method for transmitting the mapping table of the MCID and the broadcast channel IP, Patents have been previously filed. (P2007-0016757) In the present invention, it is assumed that the MBS_ZONE_ID and the MCID can be allocated without the DSA procedure as described above.

Referring to FIG. 3, when a terminal requests a pre-authentication through a default unicast flow (310), the MBSC transmits a service list and other broadcast related information for each broadcast MBS zone to the terminal. (320) MBS Zones are divided into various forms. Can be. As described above, the service can be classified into a flat fee service and a pay-as-you-go service, and each service can be classified into MBS content types (text, music, broadcast, etc.) and by broadcast field (airwave broadcast, music broadcast, and movie broadcast). , Sports broadcasts, etc.). The MBS controller (MBS controller, hereinafter referred to as MBSC) assigns and manages an independent MBS_ZONE_ID for the various services. The user selects the desired broadcasting MBS services from the service list for each MBS zone and transmits the selected information to the MBSC. (330) In the MBSC, the MBS Key for the terminal is obtained through the AAA authentication server (340). The determined MBS_ZONE_ID list, MBS Key, and MBS Key Lifetime information for the broadcast service are transmitted to the UE. (350) When the UE receives the above information, it registers the MBS_ZONE_IDs for the broadcast service in the UE and decodes the MBS burst in the future. Please note.

 4 illustrates a scenario in which the UE receives an MBS service when the terminal transitions to a synchronous state in an initial stage and is in a standby state for accessing a WiBro network. When the terminal completes the initialization operation (400), the terminal measures the RSSI value for each frequency with respect to the stored frequency information and performs the descending sorting in the order of good signal environment. (402) The most signal of the frequency information The environment attempts to acquire the synchronization in good order (404). Then, it is determined whether the synchronization is successful (406). If the synchronization is successful, the acquisition of DL-MAP, UL-MAP, DCD, and UCD is attempted. On the other hand, if synchronization acquisition fails, it is determined whether synchronization acquisition is attempted for all frequencies in the frequency list. (410) If there are remaining frequencies to be searched in the frequency list, the next frequency is selected from the frequency list sorted in descending order. (412) attempts to acquire the synchronization again (404) and if the synchronization schemes for all frequencies in the frequency list failed again Performs vaporization. 400

After acquiring the DL-MAP, the UL-MAP, the DCD, and the UCD, and confirming that all have been acquired (414), the UE transitions to a synchronous state and enters the WiBro network connection waiting state (418). If the above message is not received, the reception timer of each message is checked whether it expires (416). If the timer has not yet expired, it continues to receive messages (408). If any one of the timers expires, it returns to its original state. Attempt to initialize the terminal. (400)

On the other hand, when the WiBro network connection wait state is checked, the WiBro network connection attempt is performed (420). If a connection is attempted, the network entry process is performed and the normal state is entered.

If not attempting to access the WiBro network, the UE checks whether the Broadcast MBS service is in progress. (424) If the service is already in progress, the terminal continuously decodes the burst of the MBS Zone ID and the burst of the Broadcast MBS MCID charged through pre-authentication. The service continues to be performed (440) and the terminal remains in sync even at this time (418).

On the other hand, in step 424, if the broadcast service is not in progress, it is checked whether there is a request for a Broadcast MBS service from a higher application layer. (426) If there is no service request, the terminal maintains a synchronous state (418). If there is a service request, the terminal checks whether the terminal is authenticated through the MBS-related pre-authentication process and whether the validity period of the authentication remains.

If it is determined that the authentication is invalid, the user is notified of an authentication related error (430) and the network entry is performed to proceed with the MBS pre-authentication request operation. It is determined whether the broadcast list information of the terminal has been received.

If the broadcast list information of the current time zone is not received, the broadcast list information of the time zone transmitted every predetermined period is first received (436). When the reception is completed, the broadcast service to be received is selected from the broadcast list (438). If reception of broadcast list information is completed, the broadcast service to be received is also selected from the broadcast list. When the selection of the broadcasting service is completed, decoding of bursts of the MBS Zone ID and MCID for Broadcast MBS charged through pre-authentication is performed (440). The application displays only the selected Multicast IP broadcasting contents on the screen. Keep (418)

That is, according to an embodiment of the present invention, the terminal receives a broadcast service using information received through pre-authentication even in a synchronous state.

FIG. 5 illustrates a scenario in which a terminal receives an MBS service when the terminal transitions to a normal state and is in a WiBro network operating state. In the normal state (501), it is checked whether the broadcast MBS service is already provided. (502) If the service is provided, decoding is performed on the burst of the MBS Zone ID and the burst of the MCID for broadcast MBS charged through pre-authentication. In operation 503, a broadcast service is received. On the other hand, if the Broadcast MBS service is not in progress in step 162, it is determined whether the idle state entry timer expires (506). If the timer has not expired, the terminal checks whether the Broadcast MBS service is in progress (508). If there is no service request, the terminal maintains the normal state (501). If there is a service request, the terminal performs the MBS-related pre-authentication process. Check whether the user has received the certificate and whether the validity of the certificate remains. (509) If it is determined that the certificate is not valid, the user checks whether the user has requested MBS pre-authentication (510). After performing the MBS pre-authentication (512), and performs the steps after the successful pre-authentication. If the pre-authentication is not requested, the user is notified of an authentication-related error (511), and the terminal maintains a normal state. (501) If determined to be valid for authentication, the terminal determines whether or not the broadcast list information of the current time zone has been received. If the broadcast list information of the current time zone is not received, the broadcast list information of the predetermined time zone is transmitted first at every periodic period (174). The broadcast service to be received is selected. (514) If reception of broadcast list information of a predetermined time is completed, the broadcast service to be received is also selected from the broadcast list. When the selection of the broadcasting service is completed, decoding is performed on the burst of the MBS Zone ID and the MCID for Broadcast MBS charged through pre-authentication (515). The application program displays only the selected Multicast IP broadcasting content and maintains the normal state. (501)

6 illustrates a configuration of a terminal in a mobile communication system according to an embodiment of the present invention.

As shown, the terminal according to the present invention, the control unit 600, the transmission modem 602, the RF transmitter 604, the duplexer 606, the RF receiver 608, the reception modem 609, the state manager 612 ), A timer manager 614, and a content reproducing unit 616.

Referring to FIG. 7, first, the controller 600 performs overall processing and control for voice call and data communication. And, according to the present invention, the controller 600 controls the overall operation according to the state transition diagram as described above.

The transmission modem 602 includes a channel code block, a modulation block, and the like, and outputs a baseband modulated message from the controller 600. The channel code block includes a channel encoder, an interleaver, a modulator, and the like, and the modulation block is an IFFT (Inverse Fast Fourier Transform) for loading transmission data on a plurality of orthogonal subcarriers. ) May be configured as an operator. In consideration of an OFDM system, in the case of a CDMA system, the IFFT operator may be replaced with a code spreading modulator.

The RF transmitter 604 is composed of a frequency converter, an amplifier, and the like, and converts a baseband signal from the transmission modem 602 into a signal in a radio frequency (RF) band and outputs the signal. The duplexer 606 transmits a transmission signal (uplink signal) from the RF transmitter 604 through the antenna according to the duplexing scheme, and provides a received signal (downlink signal) from the antenna to the RF receiver 608. do. The RF receiver 608 includes an amplifier, a frequency converter, and the like. The RF receiver 608 converts a signal of an RF band passed through a wireless channel into a baseband signal and outputs the signal.

The reception modem 610 includes a demodulation block, a channel decoding block, and the like, and baseband demodulates and outputs a signal from the RF receiver 608. Here, the reception modem 609 is composed of an FFT operator for extracting data carried on each subcarrier, and the channel decoding block is composed of a demodulator, a deinterleaver, a channel decoder, and the like. Can be.

The controller 700 protocolizes the received data from the reception modem 610 and reproduces the data through the corresponding application. If the broadcast content is received, the controller 600 provides the content playback unit 616 after protocol processing of the received broadcast content. The content reproducing unit 616 may include an audio codec, an image codec, and the like. The content reproducing unit 616 reproduces the received broadcast content and outputs the same to a speaker (not shown) and a display unit (not shown).

In accordance with the present invention, state manager 612 determines the current state according to the state transition diagram described above. In addition, the state manager 612 controls the timer manager 614 according to the currently determined state. The timer manager 614 operates timers necessary for operating the above state transition diagram. That is, the timer manager 614 drives the timer under the control of the state manager 612, and notifies the state manager 612 when the timer expires. Then, the state manager 612 performs a state transition according to the expiration of the timer.

When the idle timer expires according to an embodiment of the present invention, the state manager 612 determines whether the MBS is being received, and when the MBS is being received, determines the current state as the virtual idle state to the controller 600. Notify. Then, the controller 600 performs an operation according to the virtual idle state.

According to another embodiment of the present invention, when the sleep timer expires, the state manager 612 determines whether the MBS is being received, and when the MBS is being received, determines the current state as the virtual sleep state to the controller 600. Notify. Then, the controller 600 performs an operation according to the virtual sleep state. In addition, when the idle timer expires in the virtual sleep state, the state manager 612 determines whether the MBS is being received, and when the MBS is being received, determines the current state as the virtual idle state and notifies the controller 600. do.

Meanwhile, the above-described embodiments have been described using a broadcast service in WiBro, but may be applied to a broadcast service in other wireless communication systems such as LTE, and any image that is not normal as well as a broadcast service through pre-authentication in a synchronous state. It is obvious that broadcast service can be received through pre-authentication even in the future.

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 determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

1 is a diagram illustrating a state transition diagram of a terminal in a mobile communication system according to the related art.

2 is a diagram illustrating a network structure for providing a broadcast service according to an embodiment of the present invention.

3 is a diagram illustrating a pre-authentication procedure of a terminal in a mobile communication system according to an embodiment of the present invention.

4 is a flowchart of a terminal receiving a broadcast service in a synchronous state according to an embodiment of the present invention.

5 is a flowchart of a terminal receiving a broadcast service in a normal state according to another embodiment of the present invention, and

6 is a diagram illustrating a detailed configuration of a terminal according to an embodiment of the present invention.

Claims (4)

In the mobile communication system for providing a broadcast service method of the terminal, The process of acquiring frequency synchronization The process of receiving information necessary for broadcasting service through pre-authentication Receiving a broadcast service in a synchronous state. The method of claim 1, wherein the necessary information is The method characterized in that the broadcasting service zone ID (MBS Zone ID) or broadcast service channel ID (MBS MCID) In the device of the terminal in a mobile communication system providing a broadcast service, Means for obtaining frequency-specific synchronization Means for receiving information necessary for broadcasting services through pre-authentication; Means for receiving a broadcast service in a synchronous state The method of claim 1, wherein the necessary information is The apparatus as claimed in claim 1, wherein the apparatus is a broadcast service zone ID (MBS Zone ID) or a broadcast service channel ID (MBS MCID).

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