KR20080038831A - Apparatus and method for multicast and broadcast service in broadband wireless access system - Google Patents

Abstract

The present invention relates to an apparatus and method for multicast and broadcast services in a broadband wireless access system. A method for packetizing MBS traffic in a wireless communication system providing a multicast and broadcast service (MBS) according to the present invention, the method comprising: determining a packet size and a packet period using MBS traffic rate and radio interval information; Dividing the MBS traffic according to the determined packet size, generating a header for each of the divided segments, adding the generated header to generate a custom MBS packet, and generating the generated custom MBS packet And transmitting them to the base station in consideration of the determined packet period.

Description

Apparatus and method for multicast and broadcast service in broadband wireless access system {APPARATUS AND METHOD FOR MULTICAST AND BROADCAST SERVICE IN BROADBAND WIRELESS ACCESS SYSTEM}

1 illustrates a single-base station connection scheme in accordance with MBS.

2 illustrates a multi-base station access scheme in accordance with MBS.

3 is a diagram illustrating a network structure for providing an MBS according to an embodiment of the present invention.

4 is a diagram illustrating a configuration of an upper system for performing packetization according to an embodiment of the present invention.

5 is a diagram showing a detailed configuration of a base station according to an embodiment of the present invention.

6 is a diagram illustrating an operating procedure of a higher system for performing packetization according to an embodiment of the present invention.

7 is a diagram illustrating an operation procedure of a base station according to an embodiment of the present invention.

The present invention relates to an apparatus and method for a multicast and broadcast service (MBS) in a broadband wireless access system, and more particularly, to an apparatus for synchronizing time between a plurality of base stations existing in the same broadcast zone, and It is about a method.

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 satisfied the rapidly increasing user's service needs due to 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 broadband wireless access system for efficiently providing Internet services with broadband enough to meet the demand of rapidly increasing users.

The broadband wireless access 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. The broadband wireless access system is based on a wireless medium using broadband such as 2GHz, 5GHz, 26GHz and 60GHz, in a mobile or fixed environment, public switched telephone network (PSTN), public switched data network (PSDN), internet network, IMT2000 network, It is a wireless communication system that can connect ATM (Asynchronous Transfer Mode) network and can support channel rates of 2Mbps or more. The broadband wireless access 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 terminal mobility (fixed or mobile), communication environment (indoor or outdoor), and channel transmission rate. .

The wireless access method of the broadband wireless access 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 IEEE 802.16 system has a multicast and broadcast service (MBS) service standard capable of providing multicast and broadcast to a plurality of mobile terminals. In the MBS standard, the same multicast and broadcast service area may be distinguished through different connection identifiers (CIDs) or different security associations (SAs). That is, the MBS zone (MBS_ZONE) is used to indicate that broadcast and multicast service flows are valid through CID and SA. The base station broadcasts MBS_ZONE information through a downlink channel descriptor (DCD) message. In other words, MBS_ZONE may be referred to as a base station group that uses the same CID and SA to transmit content.

The MBS service is divided into a single-BS access and a multi-BS access according to a service access method of a mobile terminal. The single-base station access method is a method in which a mobile terminal receives MBS service from one base station to which it is registered, and the multi-base station access method is a method in which a mobile terminal receives MBS service from two or more base stations simultaneously. 1 is a diagram illustrating a single-base station access method, and FIG. 2 is a diagram showing a multi-base station access method.

As shown in FIG. 2, in the multi-base station access scheme, when a mobile terminal is in a position where a neighboring cell overlaps with a cell currently serving, a signal of a neighboring cell is not a noise due to interference, but a radio frequency (RF) Frequency) acts as a signal gain by combining. This is the Macro Diversity effect. However, in order to obtain such a macro diversity effect, a signal transmitted from a serving base station and a base station of a neighboring cell must be identical. Therefore, in order to provide MBS, all base stations in MBS_ZONE must transmit the same signal at the same time.

As such, when providing the MBS, a time synchronization scheme is required so that all base stations in the same broadcast zone MBS_ZONE can transmit the same signal at the same time.

In general, the base station generates a media access control (MAC) layer packet data unit (PDU) by segmenting or packing a service data unit (eg, an IP packet) received from a network, and generates the generated MAC. PDUs are collected to generate a physical layer burst, and the physical layer burst is encoded and transmitted at a predetermined Modulation and Coding Scheme (MCS) level. As described above, the reason why the division and packing operation occurs in the base station is that the size of the packet (IP packet) received from the network is variable. Even in the case of MBS, since the size and transmission interval of the packet received from the content server (or MBS controller) are variable, the base station must perform necessary partitioning or packing on the received packet.

However, when base stations belonging to the same broadcast zone separately divide or pack MBS packets received from a network without considering synchronization, MAC PDUs having different sizes may be generated for the same content. There is a problem that the content can not be transmitted at the correct synchronization time.

In other words, in order to obtain a macro diversity effect on the MBS service, no splitting or packet operation on a service data unit (IP packet) should occur at the base station. On the other hand, in order for the splitting or packing operation not to occur at the base station, a packet received from the network must be accommodated in the MAC PDU, but there is no proposal for such a criterion.

Accordingly, an object of the present invention is to provide an apparatus and a method for all base stations in the same broadcast zone to transmit the same signal at the same time in a broadband wireless access communication system.

Another object of the present invention is to provide an apparatus and method for transmitting MBS packets received from a network without packetization at a base station in a broadband wireless access communication system.

Another object of the present invention is to provide an apparatus and method for generating an MBS packet suitable for a wireless section in a broadband wireless access communication system.

Another object of the present invention is to provide an apparatus and method for determining the size and interval of an MBS packet according to radio section scheduling information in a broadband wireless access communication system.

According to an aspect of the present invention for achieving the above object, in the apparatus for packetizing MBS traffic in a wireless communication system providing a multicast and broadcast service (MBS), the packet using the MBS traffic rate and radio interval information A control unit for determining a size and a packet period, a divider for dividing the MBS traffic according to the determined packet size, a header for each of the segments from the divider, and adding the generated header to a customized MBS And a transmission unit for generating a packet, and a transmission unit for transmitting the customized MBS packets from the header generation unit to the base station in consideration of the determined packet period.

According to another aspect of the present invention, in a base station apparatus in a wireless communication system providing a multicast and broadcast service (MBS), receiving and storing custom MBS packets packetized for a wireless section, the custom MBS at a predetermined packet period A storage unit for sequentially outputting packets, a generation unit generating a MAC PDU by adding a MAC header to a customized MBS packet from the storage unit, and encoding and modulating the MAC PDU from the generation unit according to a predetermined MCS level. And an transmitting unit for mapping and transmitting data from the encoder to a predetermined resource.

According to still another aspect of the present invention, in a method for packetizing MBS traffic in a wireless communication system providing a multicast and broadcast service (MBS), a packet size and a packet period are determined using MBS traffic rate and radio interval information. Determining, dividing the MBS traffic according to the determined packet size, generating a header for each of the divided segments, adding the generated header to generate a customized MBS packet, and And transmitting the generated custom MBS packets to the base station in consideration of the determined packet period.

According to still another aspect of the present invention, in a communication method of a base station in a wireless communication system providing a multicast and broadcast service (MBS), a process of receiving and storing custom MBS packets packetized for a wireless section in a buffer; Outputting the custom MBS packets sequentially from the buffer at the predetermined packet period, generating a MAC PDU by adding a MAC header to the output custom MBS packets, and generating the MAC PDU at a predetermined MCS level. And encoding and modulating the modulated data according to a predetermined resource.

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 when 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, a timing synchronization method for base stations belonging to the same broadcast zone (MBS_ZONE) to transmit the same signal at the same time in a broadband wireless access communication system providing a multicast and broadcast service (MBS) Let's look at.

In particular, for the time synchronization, the base station should not perform a fragmentation or packing operation on the packet received from the network. That is, the present invention is to transmit the packet to the base station by packetizing the MBS traffic in advance for the radio section in the upper system of the base station. In this case, the upper system may be, for example, an access control router (ACR) or an MBS controller (MBSC).

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

As shown, the network includes a content server 300, an MBS controller (MBSC) 302, a policy server 304, and an access control router (ACR). 306, a radio access station (RAS) 308, and a terminal 310.

Referring to FIG. 3, first, the content server 300 generates and stores broadcast content, and provides the corresponding content to the MBS controller 302 at the request of the MBS controller 302.

The policy server 304 manages Quality of Service (QoS) information for each Internet Protocol (IP) flow, and when the MBS is triggered for a specific terminal, the base station through the Computer Oracle and Password System (COPS) interface. Deliver triggering information to the system (ACR and RAS). Since the detailed operation of the policy server 304 is not directly related to the present invention, a detailed description thereof will be omitted.

The MBS controller 302 notifies the policy server 304 when a service request is received from the terminal 310. In addition, the MBS controller 302 receives the corresponding broadcast content (or broadcast traffic) from the content server 300 according to the broadcast schedule and transmits it to the terminal 310 through the base station controller 306 and the base station 308. .

The base station controller 306 transmits the broadcast content from the MBS controller 302 to the base station 308. Here, the base station controller 306 manages the connection and mobility of the terminal 310, and unique service flow (SF) for each uplink and downlink connection. Create For example, when the MBS triggering for the terminal 310 is notified from the policy server 304, a service flow for providing the MBS to the terminal 310 is generated.

The base station 308 transmits the broadcast content from the base station controller 306 to the terminal 310. In this case, the base station 308 is connected to the base station controller 306 by wire and wirelessly connected to the terminal 310. The base station 308 allocates resources to the terminal 310 by performing scheduling based on MAC (Media Access Control) layer QoS.

On the other hand, as shown, one MSB_ZONE is composed of a plurality of base stations, base stations in the same MSB_ZONE transmit the same broadcast signal at the same time. Here, an operation for transmitting the same broadcast signal by the base stations in the same broadcast zone MBS_ZONE at the same time will be described.

In order for base stations belonging to the same broadcast zone to transmit the same broadcast signal, packetization of the MBS data for the radio section by the upper system, and copying the generated MBS packet to the base stations belonging to the same broadcast zone Should be. The following description assumes that the packetization is performed in the MBS controller 302. In this case, copying of the custom MBS packet may be performed at the base station controller 306.

According to the present invention, the MBS controller 302 manages a packet size and a packet interval according to broadcast content transmission rate and air duration information (MCS level, MBS burst size) in a mapping table. Therefore, the MBS controller 302 can determine the packet size and packet period for generating a customized MBS packet by using the transmission rate and the radio section information is obtained. Here, the transmission rate of the broadcast content may be determined according to the type of content (eg, audio, video, etc.), and the wireless section information may be input by a system operator or received from the base station 308. In addition, the packet period is preferably determined by an integer multiple of the frame length of the radio section. For example, assuming that the frame length is 5ms, the packet period may be determined as 5ms, 10ms, 15ms, 20ms.

As such, when the packet size and the packet period are determined, the MBS controller 302 divides the MBS data received from the content server 300 in consideration of the packet size, and attaches a header to the divided data. Create a custom MBS packet. In this case, the header of the custom MBS packet may include absolute broadcast time information in addition to the IP header, a segment sequence number according to the division, and the like.

The MBS controller 302 then sends the custom MBS packet to the base station controller 306. Then, the MBS controller 302 copies the customized MBS packets from the MBS controller 302 by the number of base stations belonging to the same broadcast zone, and transmits the copied customized MBS packets to the base stations belonging to the same broadcast zone. . The base stations generate a customized MBS packet from the base station controller 306 as a MAC PDU (MBS burst) without partitioning or packing, and transmits the MBS burst by mapping it to a predetermined resource at a corresponding broadcast time. Accordingly, the base stations belonging to the same broadcast zone can broadcast the corresponding content using the same resources at the same time.

4 illustrates a configuration of an upper system for performing packetization according to an embodiment of the present invention. The upper system may be, for example, one of the content server 300, the MBS controller 302, and the base station controller 306. The following description will be made on the assumption that it is the MBS controller 302.

As shown, the MBS controller 302 includes a control unit 400, a wireless section information storage unit 402, a mapping table storage unit 404, a buffer 406, a partitioning unit 408, and a header generation unit 410. It is configured to include.

Referring to FIG. 4, the controller 400 controls the overall operation of the MBS controller 302. The radio section information storage unit 402 manages radio section information for each of the broadcast zones MBS_ZONE. Here, the radio section information may be input by a system operator or received from the base station 308.

The mapping table storage unit 404 manages a packet size and a packet interval according to broadcast content air rate and radio interval information (MCS level, MBS burst size) as a mapping table. For example, the mapping table may be represented as shown in Table 1 below.

Bit rate [Kbps] Wireless section information (MCS level, burst size) Packet size [Byte] Packet cycle [ms] 600 QPSK, 1/2, 4 symbols 384 5 (= 1 frame) ... ... ... ... ... ... ... ... ... ... ... ...

The control unit 400 determines the packet size and packet period for generating a customized MBS packet by accessing the mapping table with the broadcast content rate and the radio section information. The controller 400 controls the corresponding component according to the determined contents.

The buffer 406 stores the MBS data received from the content server 300 and outputs the MBS data under the control of the controller 400. The divider 408 divides and outputs MBS data from the buffer 406 according to the determined packet size. Since the determined packet size is a size including a header, the MBS data is actually divided into smaller sizes than the determined packet size.

The header generator 410 generates a header for each of the divided data from the divider 408 and adds the generated header to the divided data to generate a customized MBS packet. Here, the header may include absolute time stamp in which the custom MBS packet is broadcast, a segment sequence number according to the division, etc., in addition to a transport IP header. The generated custom MBS packet is transmitted to the base station controller 308, and copied from the base station controller 308 to the base stations belonging to the same broadcast zone.

5 shows a detailed configuration of a base station according to an embodiment of the present invention.

As shown, the base station includes a control unit 600, mapping table storage unit 502, MBS packet storage unit 504, MBS MAC PDU generation unit 506, encoder 508, OFDM modulator 510, CP An adder 512, a DAC 514, and an RF processor 516.

Referring to FIG. 5, first, the mapping table storage unit 502 manages a mapping table as shown in Table 1 above. The control unit 500 accesses the mapping table with the broadcast content transmission rate and radio interval information to obtain a packet size and a packet period of a customized MBS packet. Here, the broadcast content transmission rate may be determined according to the type of content (eg, audio and video), and the radio section information may be input by a system operator. As such, when the packet size and the packet period of the content to be broadcasted later are determined, the controller 500 performs resource scheduling using the same and controls the corresponding component according to the resource scheduling result.

The MBS packet storage unit 504 buffers the customized MBS packets received from the network, and outputs each of the buffered customized MBS packets at a corresponding time point under the control of the controller 500. The MBS MAC PDU generation unit 506 generates a packet data unit (PDU) of the MAC layer by adding a MAC header to the custom MBS packet from the MBS packet storage unit 506 to generate an encoder of a physical layer. 508). As described above, the present invention configures packets received from the network as MAC PDUs, and uses the MAC PDUs thus configured as bursts of the physical layer. That is, the packet received from the network is transmitted to the radio section as it is without partitioning or packing.

The encoder 508 codes and modulates a burst (MAC PDU) from the MAC PDU generation unit 506 to a predetermined modulation and coding scheme (MCS) level. The OFDM modulator 510 maps the MBS burst from the encoder 508 to the corresponding resource, and outputs the IFFT (Inverse Fast Fourier Transform) operation. The CP adder 512 adds and outputs a guard interval (eg, Cyclic Prefix) to the sample data from the OFDM modulator 510. The DAC 514 converts the sample data from the CP adder 512 into an analog signal and outputs the analog signal. The RF processor 516 converts the baseband signal from the DAC 514 into a signal of the RF band and transmits the signal through the antenna.

6 illustrates an operation procedure of an upper system for performing packetization according to an embodiment of the present invention. The upper system may be, for example, one of the content server 300, the MBS controller 302, and the base station controller 306. The following description will be made on the assumption that it is the MBS controller 302.

Referring to FIG. 6, first, the MBS controller 302 checks the transmission rate of broadcast content to be transmitted to the base station controller 306 and radio section information of the corresponding broadcast zone MBS_ZONE in step 601. Here, the transmission rate of the broadcast content may be determined according to the type of content (eg, audio, video, etc.), and the wireless section information may be input by a system operator or received from the base station 308.

When the transmission rate and the radio interval information are confirmed, the MBS controller 302 accesses a predetermined mapping table (Table 1) with the transmission rate and the radio interval information in step 603 to obtain a packet size and packet period of a customized MBS. do. In step 605, the MBS controller 302 divides MBS data to be transmitted to the base station controller 306 according to the packet size.

The MBS controller 302 generates a header for each of the divided data in step 607. In this case, the header may include absolute time information on which a custom MBS packet is broadcast in addition to the IP header, a segment sequence number according to the division, and the like. In step 609, the MBS controller 302 adds the generated header to the divided data to generate a customized MBS packet. As such, when the customized MBS packet is generated, the MBS controller 302 transmits the generated customized MBS packets to the base station controller 306 in step 611.

Meanwhile, the base station controller 306 copies the customized MBS packets received from the MBS controller 302 by the number of base stations belonging to the same broadcast zone, and transmits the copied customized MBS packets to the base stations belonging to the same broadcast zone. do.

7 illustrates an operation procedure of a base station according to an embodiment of the present invention.

Referring to FIG. 7, the base station 308 first checks transmission rate and radio section information of content to be broadcasted in step 701. Here, the transmission rate of the broadcast content may be determined according to content (eg, audio, video, etc.), and the wireless section information may be input by a system operator.

When the transmission rate and the wireless interval information are confirmed, the base station 308 accesses a predetermined mapping table (Table 1) with the transmission rate and the wireless interval information in step 703 to determine the packet size and packet period of the customized MBS. . The determined packet size and packet period may be used for resource scheduling.

In step 705, the base station 308 detects reception of the corresponding broadcast content. If the reception of the broadcast content is detected, the base station 308 proceeds to step 707 to buffer custom MBS packets received from the base station controller 306.

In step 709, the base station 308 checks whether a transmission time according to the packet period has been reached. When the transmission time is reached, the base station 308 generates a packet data unit (PDU) of the MAC layer by adding a MAC header to the corresponding MBS packet in step 711. In step 713, the base station 308 codes and modulates the generated MAC PDU (MBS burst) at a predetermined MCS level, and transmits the modulated data by mapping the modulated data to a predetermined resource. The base station 308 then returns to step 709 for the next transmission. As described above, the present invention configures a packet (service data unit) received from the network as it is as a MAC PDU, and transmits the MAC PDU configured as described above as a physical layer burst.

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 the equivalents of the claims.

As described above, the present invention has an advantage that base stations belonging to the same broadcast zone can perform timing synchronization in a broadband wireless access system providing multicast and broadcast services (MBS). That is, according to the present invention, since the MBS traffic is packetized in advance according to the radio section in the upper system of the base station and transmitted to the base station, that is, since no fragmentation or packing is performed at the base station, broadcasting is performed. There is an advantage that time synchronization can be easily performed for the traffic.

Claims (24)

An apparatus for packetizing MBS traffic in a wireless communication system providing MBS (Multicast and Broadcast Service), A control unit for determining a packet size and a packet period by using MBS traffic rate and radio section information; A divider for dividing the MBS traffic according to the determined packet size; A header generation unit generating a header for each of the segments from the division unit, and adding the generated header to generate a custom MBS packet; And a transmitter for transmitting the customized MBS packets from the header generator to the base station in consideration of the determined packet period. The method of claim 1, And a storage unit for managing a packet size and a packet period according to the MBS traffic rate and radio section information by using a mapping table. The method of claim 1 And the header includes at least one of an IP header, absolute time information broadcasted, and a segment sequence number. The method of claim 1, The radio section information, characterized in that the modulation and coding scheme (MCS) level and MBS burst size. The method of claim 1 Wherein the packet size is a size that can be accommodated in a Media Access Control (MAC) layer packet data unit (PDU) of a base station. The method of claim 1, And said packet period is an integer multiple of a frame length of a wireless section. A base station apparatus in a wireless communication system providing a multicast and broadcast service (MBS), A storage unit for receiving and storing custom MBS packets packetized according to a wireless section, and sequentially outputting the custom MBS packets at a predetermined packet period; A generation unit for generating a MAC PDU by adding a MAC header to a customized MBS packet from the storage unit; An encoder for coding and modulating the MAC PDU from the generation unit according to a predetermined MCS level; And a transmitter for mapping and transmitting data from the encoder to a predetermined resource. The method of claim 7, wherein The size and the packet period of the custom MBS packet is determined according to the MBS traffic rate and radio section information. The method of claim 8, The radio section information, characterized in that the modulation and coding scheme (MCS) level and MBS burst size. The method of claim 8. The size of the custom MBS packet is characterized in that the size that can be accommodated in the Media Access Control (MAC) layer packet data unit (PDU) of the base station. The method of claim 7, wherein And said packet period is an integer multiple of a frame length of a wireless section. The method of claim 7, wherein Wherein the header of the custom MBS packet includes at least one of an IP header, broadcast absolute time information, and a segment sequence number. In the method for packetizing MBS traffic in a wireless communication system providing a multicast and broadcast service (MBS), Determining packet size and packet period using MBS traffic rate and radio segment information; Dividing the MBS traffic according to the determined packet size; Generating a header for each of the divided segments and adding the generated header to generate a custom MBS packet; And transmitting the generated custom MBS packets to a base station in consideration of the determined packet period. The method of claim 13, wherein the determination process, Acquiring MBS traffic rate and radio segment information; And determining the packet size and the packet period by accessing a predetermined mapping table with the obtained information. The method of claim 13, And the header includes at least one of an IP header, broadcast absolute time information, and a segment sequence number. The method of claim 13, The radio section information is characterized in that the modulation and coding scheme (MCS) level and MBS burst size. The method of claim 13, The packet size may be a size that can be accommodated in a Media Access Control (MAC) layer packet data unit (PDU) of a base station. The method of claim 13, Wherein the packet period is an integer multiple of a frame length of a radio section. In a communication method of a base station in a wireless communication system providing a multicast and broadcast service (MBS), Receiving and storing custom MBS packets packetized for the wireless section in a buffer; Outputting the custom MBS packets sequentially from the buffer at the predetermined packet period; Generating a MAC PDU by adding a MAC header to the output customized MBS packet; Encoding and modulating the generated MAC PDU according to a predetermined MCS level; And mapping the modulated data to a predetermined resource and transmitting the same. The method of claim 19, The size of the custom MBS packet and the packet period is determined according to the MBS traffic rate and radio section information. The method of claim 20, The radio section information is characterized in that the modulation and coding scheme (MCS) level and MBS burst size. The method of claim 20. The size of the custom MBS packet is characterized in that the size that can be accommodated in the Media Access Control (MAC) layer packet data unit (PDU) of the base station. The method of claim 19, Wherein the packet period is an integer multiple of a frame length of a radio section. The method of claim 19, And the header of the custom MBS packet includes at least one of an IP header, broadcast absolute time information, and a segment sequence number.

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