WO2013187667A1 - Rate adaptation method using bit error rate for multimedia service and apparatus therefor - Google Patents

Abstract

Rate adaptation is carried out using bit error rate (BER) to enable effective multimedia transmission. The BER can be estimated using signal strength in a MAC layer and modulation information (figures 7-9), and can be compatibly used in different wireless networks by means of message standardization.

Description

Rate adaptation method using bit error rate for multimedia service and device therefor

The present invention relates to a multimedia transmission method, and more particularly, to an effective multimedia transmission method and apparatus using a bit error rate.

In wireless environments, many bit errors occur due to weak signal strength, which results in packet loss. In order to overcome the above problems associated with real-time video transmission, rate control using forward error correction (FEC) has been introduced.

To reduce this packet loss in a wireless environment, it is necessary to estimate link quality or channel conditions. In particular, for real-time video transmission, it is essential to accurately estimate the radio channel capacity in real time. This is because wireless link conditions and link quality may vary depending on interference, fading, multi-path effects, and mobility. This is because a significant change in channel capacity eventually occurs.

That is, it is very important to accurately estimate or predict a radio channel condition in order to set an appropriate channel coding rate in order to provide improved video quality in real time video transmission.

For example, when watching a multimedia content stream through an WLAN (IEEE 802.11b) wireless network installed in an office, severe distortion of the multimedia content stream may be caused by a channel environment such as interference by an access point (AP) located in another office. significant deterioration may occur.

Conventional techniques for estimating link quality or channel conditions include the Wireless LAN Protocol ('CON protocol'), which discards packets with one or more residual errors (MAC layer errors). This estimates the link quality or channel capacity using the Packet Error Rate (PER).

Since the conventional technology predicts link quality or channel capacity using a packet loss rate (PER) rather than a bit error rate (BER), the accuracy of the prediction is low, resulting in poor channel adaptability. There was a problem that does not guarantee.

An object of the present invention is to provide an effective multimedia transmission method using a bit error rate.

Multimedia reception method using a bit error rate according to an embodiment of the present invention for solving the above problems is a bit error rate of a plurality of different layers including at least one of a physical (PHY) layer and a MAC (Media Access Control) layer Generating a message including an indicator indicating the generated layer.

The bit error rate may be estimated using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.

The message further includes a parameter indicating the bit error rate, and the indicator indicating the layer in which the bit error rate is generated may belong to a portion of the parameter indicating the bit error rate.

An indicator indicating the layer in which the bit error rate is generated may be located in the first bit of the parameter representing the bit error rate.

An indicator indicating the layer at which the bit error rate was generated and transmitting the generated bit error rate to a transmitting device, or channel state, wherein the channel state is an indicator indicating the layer at which the bit error rate was generated and the bit error rate. Created using-the method may further include transmitting to the transmitting device.

An indicator indicating the layer in which the bit error rate is generated may be transmitted between layers of a receiving device through a cross layer interface (CLI).

In addition, the multimedia transmission method using a bit error rate to solve the above problem indicates a layer in which a bit error rate is generated from a plurality of different layers including at least one of a physical (PHY) layer and a Media Access Control (MAC) layer. And receiving a message including an indicator.

The bit error rate may be estimated and generated using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.

Receiving a Media Fragment Unit (MFU) having a format independent of a specific media codec from a media codec layer; Generating a Media Processing Unit (MPU) using the media fragment unit; Encapsulating the generated media processing unit to generate an MMT asset; Generating an MMT package by encapsulating the generated MMT asset; Receiving the generated MMT package and generating an MMT payload; And generating an MMT transport packet using the generated MMT payload.

A coding rate may be selected by performing a rate control of media data to be transmitted based on the bit error rate in the generated message.

The method may further include coding media at the coding rate based on the generated bit error rate to transmit media data to a receiving apparatus.

The additional information may include at least one of signal strength, modulation information, and ambient wireless traffic information.

In addition, the channel state estimation method using the bit error rate according to an embodiment of the present invention for solving the above problem, in the method for estimating the channel state using the bit error rate, at least one of a physical layer and a MAC layer Generating the bit error rate using additional information among a plurality of different layers, and including the generated bit error rate and an indicator of the layer in which the bit error rate is generated and transmitting the message to another layer. .

The bit error rate may be estimated using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.

In addition, the multimedia reception apparatus using a bit error rate according to an embodiment of the present invention for solving the above problems is a plurality of different layers including at least one of a physical (PHY) layer and a MAC (Media Access Control) layer And a bit error rate (BER) generation unit for generating a message including an indicator indicating the layer where the bit error rate is generated.

The bit error rate may be estimated using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.

The BER generator may further include a channel estimator configured to receive a bit error rate and information on a layer in which the bit error rate is generated and estimate a channel state.

The message further includes a parameter indicating the bit error rate, and the indicator indicating the layer in which the bit error rate is generated may belong to a portion of the parameter indicating the bit error rate. The channel estimator may transmit the estimated channel state to the transmitter.

The indicator indicating the layer in which the bit error rate is generated may have a value of 0 when the layer in which the bit error rate is generated is a physical layer.

The apparatus may further include a cross layer interface (CLI) of an MPEG Media Transport (MMT) system, and the cross layer interface may transfer an indicator indicating a layer in which the bit error rate is estimated.

In addition, the multimedia transmission apparatus using a bit error rate according to an embodiment of the present invention for solving the above problems is a media data generation unit for generating media data to be transmitted; A transmitter for transmitting the media data generated by the media data generator; And a rate tuner for controlling the operation of the media data generator according to the channel information received from the receiver, wherein the channel information includes at least one of a physical (PHY) layer and a media access control (MAC) layer. A message including an indicator indicating a layer from which a bit error rate is generated among a plurality of different layers of the channel information or channel state information generated by a receiving apparatus using the indicator.

The bit error rate may be estimated and generated using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.

A media fragment generation unit receiving a media fragment unit (MFU) having a format independent of a specific media codec from a media codec layer; A media processing unit generation unit generating a media processing unit (MPU) using the media fragment unit; An MMT asset generator for generating an MMT asset by encapsulating the generated media processing unit; An MMT package generator for generating an MMT package by encapsulating the generated MMT asset; An MMT payload generator configured to receive the generated MMT package and generate an MMT payload; And an MMT transport packet generator configured to generate an MMT transport packet using the generated MMT payload, wherein the media data generator is channel-coded the MMT transport packet generated by the MMT transport packet generator to transmit the media. You can generate data.

The rate tuner may select a coding rate by controlling the rate of the media data based on the received channel information.

The media data generator may generate the media data by coding a channel at the coding rate, and the transmitter may transmit the media data to a client.

In addition, an apparatus for estimating a channel state using a bit error rate according to an embodiment of the present invention for solving the above problem includes an at least one of a physical layer and a MAC layer. A BER generator for generating the bit error rate by using additional information among a plurality of different layers; And an interlayer transmission unit including the measured bit error rate and an indicator of a layer in which the bit error rate is generated and transmitting the message to another layer.

The bit error rate may be estimated using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.

Effective multimedia transmission is possible by performing rate adaptation using BER, and BER can be estimated using signal strength and modulation information in MAC layer, and it is compatible with different wireless networks by standardizing messages. Can be used.

1 is a conceptual diagram illustrating a MPEG Media Transport (MMT) hierarchical structure.

2 is a conceptual diagram illustrating a format of unit information (or data or packet) used for each layer of the MMT hierarchical structure.

3 is a conceptual diagram of an MMT package configuration.

4 is a diagram illustrating a problem that occurs when using a packet loss rate (PER) for rate adaptation.

FIG. 5 is a conceptual diagram comparing case of using PER and rate of BER in case 1 of FIG. 4 in terms of throughput.

6 is a block diagram of a multimedia system using BER according to an embodiment of the present invention.

7 to 9 are graphs showing correlations between BER and signal to noise ratio (SNR) of 802.11a, 802.11g, and WiMax wireless networks, respectively.

10 and 11 are flowcharts illustrating rate adaptation in a wireless network according to an embodiment of the present invention.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is said to be "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that another component may be present in the middle. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present disclosure does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, the meaning of the term is defined as follows.

The content component or media component is defined as a media of a single type or a subset of the media of a single type. , Video tracks, movie subtitles, or a video enhancement layer of video.

Content is defined as a set of content components, and may be, for example, a movie or a song.

Hybrid delivery defines one or more content components to be transmitted simultaneously through one or more physically different types of networks.

A presentation is defined as an operation performed by one or more devices to allow a user to experience one content component or one service (eg, watch a movie).

A service is defined as one or more content components that are transmitted for presentation or storage.

Service information is defined as metadata describing one service, characteristics and components of the service.

Hereinafter, the first network or the second network may include various networks including a broadcast network, a broadband network, a cable network, or a satellite communication network. It includes.

Hereinafter, the hybrid transmission may be transmitted in MMT asset unit, substream unit, MMT package unit, or MMT packet unit. In addition, when video content includes a plurality of layers such as a first layer and a second layer, hybrid transmission may be performed in a layer unit. .

An access unit (AU) is the smallest data entity that can have time information as an attribute. If coded media data for which decoding and presentation time information is not specified is relevant, the AU is not defined.

An MMT asset is a logical data entity consisting of at least one MPU with the same MMT asset ID or a specific chunk of data with a format defined by other standards. The MMT asset is the largest data unit to which the same composition information and transmission characteristics apply.

MMT Asset Delivery Characteristics (MMT-ADC) (or MMT Asset Delivery Characteristics) is a description related to QoS requirements for delivering MMT assets. MMT-ADC is expressed as a parameter unrelated to a specific transmission environment, so that the specific transmission environment is not known.

MMT Composition Information (MMT CI) describes spatial and temporal relationships between MMT assets.

Media Fragment Unit (MFU) is a general container, which is independent of any particular codec, and accommodates encoded media data that can be consumed independently by a media decoder. It has information that is less than or equal to the access unit (AU) and can be used at the transport layer.

An MMT entity is an implementation of software or hardware that follows the MMT profile.

An MMT package is a collection of logically structured data and includes at least one MMT asset, MMT composition information, MMT asset asset, and descriptive information.

The MMT packet is a format of data generated or consumed by the MMT protocol.

MMT payload format is a format for payload of MMT package or MMT signaling message to be delivered by MMT protocol or Internet Application Layer Protocol (eg RTP).

An MMT Processing Unit (MPU) or Media Processing Unit (MPU) is a generic container that is independent of any particular media codec and accommodates at least one AU and information related to additional transmission and consumption. For non-temporal data, the MPU accepts a portion of data that does not fall within the AU range. MPU is encoded media data that can be processed completely and independently. In this context, processing means encapsulation or packetization into an MMT package for transmission. MPU is encoded media data that can be processed completely and independently. However, for scalable video coding (SVC) and multiview video coding (MVC), in some cases the MPU may not be consumed independently and completely at the media codec server.

Non-timed data defines all data elements that are consumed without specifying time. Non-timed data can have a time range within which the data can be executed or started.

Timed data defines data elements associated with a particular time to be decoded and presented.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In the following description of the present invention, the same reference numerals are used for the same elements in the drawings and redundant descriptions of the same elements will be omitted.

1 is a conceptual diagram illustrating an MMT hierarchical structure.

Referring to FIG. 1, the MMT layer includes an encapsulation layer, a delivery layer, and a functional area of a signaling layer (S layer). The MMT layer operates on a transport layer.

The encapsulation layer (E-layer) may be responsible for, for example, packetization, fragmentation, synchronization, multiplexing, and the like of transmitted media.

The encapsulation functional area defines the logical structure of the format of the media content, the MMT package, and the data units to be processed by the MMT compliant entity. In order to provide the necessary information for adaptive delivery, the MMT package specifies the components that contain the media content and the relationships between them. The format of the data units is defined to encapsulate the encoded media to be stored or transmitted in the payload of the transport protocol and to be easily converted between them. That is, the format of the data units is defined to encapsulate the encoded media for storage or delivery, and to easily convert between the two formats.

Encapsulation layer (E-layer), as shown in Figure 1, MMT E.1 Layer (MMT E.1 Layer), MMT E.2 Layer (MMT E.2 Layer) and MMT E.3 Layer (MMT) E.3 Layer).

The E.3 layer encapsulates a Media Fragment Unit (MFU) provided from the Media Codec (A) layer to create a Media Processing Unit (MPU).

Encoded media data from the upper layer is encapsulated in MFU. The type and value of the encoded media are abstracted to allow the MFU to be commonly used in certain codec technologies. This allows the lower layer to process the MFU without access to the encapsulated encoded media. This allows the lower layer to process the MFU without access to the encapsulated encoded media, which loads the required encoded media data from the network or storage buffer and sends it to the media decoder. The MFU has enough information media subunits to perform this operation.

The MFU may have a format, independent of any particular codec, that can carry data units that can be consumed independently in the media decoder. The MFU can be, for example, a picture or slice of the video.

One or a group of multiple MFUs that can be independently transmitted and decoded create an MPU. Non-temporal media that are independently transportable and executable also create an MPU. MPUs describe internal structures such as the arrangement and pattern of MFUs that allow for quick access and partial consumption of MFUs.

The E.2 layer encapsulates the MPUs created in the E.3 layer to generate MMT assets.

A sequence of MPUs from the same source component creates an MMT asset. The MMT asset is packaged by the MMT package, configured by the MMT Composition Information (MMT-CI), the other by the MMT Transport Characteristics (MMT-TC), and multiplexed with the other by the MMT payload format. Is transmitted by the MMT protocol.

An MMT asset is a data entity composed of one or a plurality of MPUs from a single data source and is a data unit in which composition information and transport characteristics are defined. Transport characteristics may be referred to as Asset Delivery Characteristics (ADC). MMT assets can correspond to packetized elementary streams (PES), for example video, audio, program information, MPEG-U widgets, JPEG images, MPEG 4 file format, M2TS (MPEG transport stream), etc.

The E.1 layer creates an MMT package by encapsulating the MMT asset generated in the E.2 layer.

The MMT asset is packaged with MMT composition information (MMT-CI) for later response of the same user experience together or separately with other functional areas—transmission area and signal area. The MMT package is also packaged with a delivery characteristic or asset delivery characteristics (ADC) for selecting an appropriate delivery method for each MMT asset to satisfy the haptic quality of the MMT asset.

Referring to FIG. 3, the MMT package 450 may include one composition information 162 and additional information such as at least one transport characteristic 164 or asset delivery characteristics (ADC). It may be composed of one or a plurality of MMT assets 150 together. Composition information 162 includes information on the relationship between MMT assets, and indicates the relationship between a plurality of MMT packages when one content consists of a plurality of MMT packages. It may further include information for betting. The transport characteristics 164 may include transport characteristic information necessary for determining a delivery condition of an MMT asset or an MMT packet, and may include, for example, a traffic description parameter and a QoS descriptor ( QoS descriptor). The MMT package may correspond to a program of MPEG-2 TS.

In addition, processing of the package is applied on an MPU basis, and an asset is a set of at least one MPU having the same asset ID, and one package includes one composition information, at least one MPU, and an asset transmission characteristic associated with each asset. It can be said that it is configured.

Composition information includes information about a relationship between MMT assets, and when one content consists of a plurality of MMT packages, the composition information indicates a relationship between a plurality of MMT packages. It may further include information.

Asset Delivery Characteristics (ADCs) represent QoS requirements and statistics for asset delivery. Multiple assets may be associated with one ADC. The ADC can be used to set the parameters of the MMT payload and the MMT protocol by the entity packetizing the package for effective delivery of the asset.

Asset Delivery Characteristics (ADCs) may include delivery characteristic information necessary to determine delivery conditions of MMT assets or MMT packets, for example, traffic description parameters and QoS. It may include a descriptor (QoS descriptor).

A delivery layer (D-layer) defines a payload format and an application layer transport protocol. Payload format is defined to carry coded media data regardless of media type or encoding method. Application layer transport protocols provide enhanced features for package delivery including multiplexing and cross-layer communication.

The delivery layer may perform, for example, network flow multiplexing, network packetization, and QoS control of media transmitted through a network.

A delivery layer or delivery functional area defines the application layer protocol and format of the payload. The application layer protocol in the present invention provides enhanced features for the delivery of MMT packages as compared to conventional application layer protocols for the transmission of multimedia including multiplexing. Payload format is defined to carry coded media data regardless of media type or encoding method.

The transport layer (D-layer) is a packet level between the transport layer and the encapsulation layer (E-layer), such as the multiplexing of the media such as video, audio, etc. transmitted over the network. Aggregation and / or Fragmentation, Network Packetization, QoS Control, Synchronization, Transport Layer like RTP, Conventional UDP, TCP It is responsible for the interface with the port layer (Transport layer), encapsulation layer (E-layer), signaling layer (S layer).

The transport layer (D-layer) identifies different types of payloads from the encapsulation layer (E-layer) to handle payloads from the encapsulation layer (E-layer). The transport layer (D-layer) may handle the temporal relation between packets transmitted through different networks and different channels. The synchronization function may include hybrid network synchronization using a time stamp or the like.

The D-layer may handle timing constraints of MMT delivery packets for real-time media transmission. The D-layer may perform error control of MMT media packets such as forward error correction and retransmission. The transport layer (D-layer) may perform flow control of the MMT media packet. The transport layer (D-layer) interacts with other MMT layers as well as lower layers (MAC, PHY) through a cross-layer design to maintain a certain level of QoS for delivery of MMT media packets. interaction). In addition, the transport layer (D-layer) may provide a function for performing group communication.

The transport layer (D-layer), as shown in Figure 1, MMT D.1 Layer (MMT D.1 Layer), MMT D.2 Layer (MMT D.2 Layer) and MMT D.3 Layer (MMT) D.3 Layer).

The D.1 layer receives the MMT package generated in the E.1 layer and generates an MMT payload format. The MMT payload format is a payload format for carrying MMT assets and for transmitting information for consumption by the MMT application protocol or other existing application transport protocol such as RTP. The MMT payload may include a fragment of the MFU along with information such as AL-FEC.

The MMT payload format is defined as a general payload format for packetization of content components of a package. The MMT payload format is defined irrespective of a particular media codec so that any type of media encapsulated, such as an MPU, can be packetized into a payload for an application layer transport protocol that supports streaming delivery of media content. The MMT payload can be used as payload format for RTP, MMT and other packet transfer protocols. The MMT payload may be used to packetize the signaling message.

The D.2 layer receives the MMT payload format generated in the D.1 layer and generates an MMT transport packet or an MMT packet. The MMT transport packet or MMT packet is a data format used in an application transport protocol for MMT.

D.3 layer (D.3-layer) supports QoS by providing the function of exchanging information between layers by cross-layer design. For example, the D.3 layer may perform QoS control using QoS parameters of the MAC / PHY layer. The QoS parameters of the MAC / PHY may be, for example, bitrate, packet loss ratio, expected delay, available buffer size, and the like.

The S layer or signaling layer (S layer) performs a signaling function. For example, session initialization / control / management of transmitted media, server-based and / or client-based trick modes, service discovery, synchronization, and other layers, i.e., delivery A signaling function for interfacing with a D-layer and an encapsulation layer (E-layer) may be performed. The synchronization may include synchronization control in a hybrid network.

The signaling layer or signaling functional area defines the format of the message that manages the delivery and consumption of the MMT package. The message for consumption management is used to transmit the structure of the MMT package, and the message for delivery management is used to transmit the structure of the payload format and the configuration of the protocol.

As illustrated in FIG. 1, the S layer may include an MMT S.1 layer and an MMT S.2 layer.

S.1 layer includes service discovery, media session initialization / termination of media, media session presentation / control of media, delivery (D) layer and encapsulation (E). The interface function with the layer can be performed. The S.1 layer may define the format of control messages between applications for media presentation session management. The presentation session management may define a format of a control message exchanged between applications for providing media presentation, session management, and information required for media consumption.

The S.2 layer is responsible for flow control, delivery session management, delivery session monitoring, error control, and hybrid network synchronization control. It is possible to define the format of the control message exchanged between delivery end-points of the D-layer.

The S.2 layer supports delivery session establishment and release, delivery session monitoring, flow control, error control, resource scheduling for established delivery sessions, and synchronization in a complex delivery environment to support the behavior of the delivery layer. Signaling for adaptive delivery, and signaling for adaptive delivery. Required signaling may be provided between a sender and a receiver. That is, the S.2 layer may provide signaling required between the sender and the receiver in order to support the operation of the transport layer as described above. In addition, the S.2 layer may be responsible for interfacing with the transport layer and the encapsulation layer.

The control message or control information may be generated in the signaling layer and transmitted through a broadcasting network and / or a broadband network.

FIG. 2 illustrates a format of unit information (or data or packet) used for each layer of the MMT hierarchical structure of FIG. 1.

The media fragment unit (MFU) 130 includes coded media fragment data 132 and a media fragment unit header (MFUH) 134. The media fragment unit 130 has a general container format independent of a specific codec and carries the smallest data unit that can be consumed independently in a media decoder. The MFUH 134 may include additional information such as media characteristics-for example, loss-tolerance. MFU) 130 may be, for example, a picture or slice of a video.

The Media Fragment Unit (MFU) defines a format that encapsulates a portion of the AU in the transport layer to perform adaptive transmission in the range of MFU. The MFU may be used to transmit certain types of encoded media so that portions of the AU can be independently decoded or discarded.

The MFU has an identifier for distinguishing one MFU from other MFUs and has general relationship information between MFUs in a single AU. The dependencies between the MFUs in a single AU are described, and the relevant priorities of the MFUs are described as part of such information. The information can be used to handle the transmission at the lower transport layer. For example, the transport layer may omit the transmission of MFUs that may be discarded to support QoS transmission in insufficient bandwidth.

The MPU is a collection of media fragment units including a plurality of media fragment units 130. The MPU has a general container format independent of a specific codec and includes media data equivalent to an access unit. The MPU may have a timed data unit or a non-timed data unit.

MPU is data that is independently and completely processed by an entity following the MMT, and processing includes encapsulation and packetization. An MPU may consist of at least one MFU or have a portion of data having a format defined by another standard.

A single MPU may accommodate the integral number or non-time data of at least one AU. For time data, an AU may be delivered from at least one MFU, but one AU may not be divided into multiple MPUs. In non-time data, one MPU receives a portion of non-time data that has been independently and completely processed by an entity that complies with the MMT.

An MPU can be uniquely identified within an MMT package with a sequence number and an associated asset ID that distinguishes it from other MPUs.

The MPU has at least one random access point. The first byte of the MPU payload can always start with a random access point. In time data, this fact means that the decoding order of the first MFU in the MPU payload is always zero. In the time data, the presentation period and decoding order of each AU can be sent to inform the presentation time. The MPU does not have its initial presentation time, and the presentation time of the first AU of one MPU may be described in the composition information. The composition information may specify the first presentation time of the MPU.

The MMT asset 150 is a collection of MPUs composed of a plurality of MPUs. The MMT asset 150 is a data entity composed of multiple MPUs (timed or non-timed data) from a single data source, and the MMT asset information 152 is an asset packaging metadata (Asset). additional information such as packaging metadata) and data type. MMT asset 150 may include, for example, video, audio, program information, MPEG-U widgets, JPEG images, MPEG 4 FF (File Format), packetized elementary streams (PES), and MPEG transport (M2TS). streams).

In addition, the MMT asset may be a logical data entity having encoded media data. The MMT asset has an MMT asset header and encoded media data. The encoded media data may be a group of MPUs collectively referred to by the same MMT asset ID. The type of data consumed as an entity directly related to the MMT client may be a separate MMT asset. Examples of such data types are MPEG-2 TS, PES, MP4 file, MPEG-U Widget Package, JPEG files.

The encoded media of the MMT asset may be time data or non-time data. Temporal data is audiovisual media data that requires synchronized decoding and presentation of specific data at specified times. Non-timed data is data of a data type that can be decoded and provided at any time in accordance with the provision of a service or user interaction.

A service provider may create a multimedia service by integrating MMT assets and putting MMT assets on a space-time axis.

The MMT package 160 is a collection of MMT assets including one or more MMT assets 150. MMT assets in an MMT package may be multiplexed or concatenated.

The MMT package is a container format for MMT asset and configuration information. The MMT package provides a repository of MMT assets and configuration information for the MMT program.

The MMT program provider generates configuration information by encapsulating the encoded data into MMT assets and describing the temporal and spatial layout of the MMT assets and their transmission characteristics. MU and MMT assets may be sent directly in D.1 payload format. The configuration information may be sent by an S.1 presentation session management message. However, MMT program providers and clients that allow relaying or future reuse of MMT programs store them in MMT package format.

In parsing the MMT package, the MMT program provider determines which transmission path (eg, broadcast or broadband) the MMT asset will be provided to the client. Configuration information in the MMT package is transmitted in a C.1 presentation session management message along with transmission related information.

The client receives the S.1 Presentation Session Management message to learn which MMT programs are available and how to receive MMT assets for the corresponding MMT program.

The MMT package can also be transmitted by the D.1 payload format. The MMT package is packetized and delivered in D.1 payload format. The client receives the packetized MMT package and configures all or part of it, where it consumes the MMT program.

The package information 165 of the MMT package 160 may include configuration information. Configuration Information includes a list of MMT assets, package identification information, composition information 162 and transport characteristics 164 or Asset Delivery Characteristics (ADCs). May include additional information such as Composition information 162 includes information about a relationship between MMT assets 150.

The composition information 162 may further include information for indicating a relationship between a plurality of MMT packages when one content includes a plurality of MMT packages. Composition information 162 may include information about temporal, spatial and adaptive relations in an MMT package.

Like information to assist in the transmission and presentation of the MMT package, Composition Information in the MMT provides information about the spatial and temporal relationships between MMT assets in the MMT package.

MMT-CI is an explanatory language that extends HTML5 to provide such information. If HTML5 is designed to describe page-based presentations of text-based content, MMT-CI mainly represents spatial relationships between sources. In order to support the presentation of the temporal relationship between MMT assets, information related to MMT assets in an MMT package, such as presentation resources, time information for determining the order in which MMT assets are sent and consumed, and various MMT assets are consumed in HTML5. It can be extended to have additional properties of media elements. Detailed description will be described later.

Asset Delivery Characteristics (ADC) or transport characteristics information (164) includes information about the transmission characteristics, and determines the delivery condition (delivery condition) of each MMT asset (or MMT packet) To provide the necessary information. Asset delivery characteristics (ADC) or transmission characteristic information may include a traffic description parameter and a QoS descriptor.

The traffic description parameter may include bitrate information, priority information, or the like for the media fragment unit (MFU) 130 or the MPU. The bitrate information is for example information about whether the MMT asset is Variable BitRate (VBR) or Constant BitRate (CBR), guaranteed bitrate for the Media Fragment Unit (MFU) (or MPU). ), The maximum bit rate for the media fragment unit (MFU) (or MPU). The traffic description parameter may be used for resource reservation between servers, clients, and other components on a delivery path, for example, maximum size information of a media fragment unit (MFU) (or MPU) in an MMT asset. It may include. The traffic description parameter may be updated periodically or aperiodically.

The QoS descriptor includes information for QoS control and may include, for example, delay information and loss information. The loss information may include, for example, a loss indicator of whether delivery loss of the MMT asset is allowed or not. For example, a loss indicator of '1' may indicate 'lossless', and a '0' indicates 'lossy'. The delay information may include a delay indicator used to distinguish the sensitivity of the transmission delay of the MMT asset. The delay indicator may indicate whether the type of the MMT asset is conversation, interactive, real time, and non-realtime.

One content may consist of one MMT package. Alternatively, one content may consist of a plurality of MMT packages. When one content consists of a plurality of MMT packages, composition information or composition information indicating temporal, spatial, and adaptive relations between the plurality of MMT packages ( configuration information) may exist inside one MMT package or outside the MMT package.

For example, in the case of hybrid delivery, some of the content components are transmitted through a broadcast network and the rest of the content components are transmitted through a broadband network. Can be. For example, in the case of a plurality of audio visual streams constituting one multi-view service, one stream may be transmitted to a broadcasting network and the other stream may be transmitted to a broadband network, and each AV stream may be multiplexed and transmitted to a client terminal. Can be individually received and stored. Alternatively, there may be a scenario in which application software such as a widget is transmitted to a broadband network and an AV stream (AV program) is transmitted to an existing broadcasting network. Also, in another example, one media component may be transmitted over a broadband network and another media component may be transmitted over another broadband network.

In the multi-view service scenario and / or widget scenario as described above, the entire plurality of AV streams may be a single MMT package, and in this case, one of the plurality of streams may be stored in only one client terminal. The storage content becomes part of the MMT package, and the client terminal needs to rewrite the composition information or the configuration information, and the rewritten content becomes a new MMT package independent of the server. .

In the multi-view service scenario and / or widget scenario as described above, each AV stream may be one MMT package, and in this case, a plurality of MMT packages constitute one content, and storage Storage is recorded in MMT package units and requires composition information or configuration information indicating a relationship between MMT packages.

The composition information or configuration information included in one MMT package may refer to an MMT asset in another MMT package, and may refer to an outside of an MMT package that refers to the MMT package in an out-band situation. I can express it.

Meanwhile, in order to inform the client terminal of a list of MMT assets 160 provided by a service provider and a possible path for delivery of the MMT package 160, the MMT package 160 is controlled through a control (C) layer. Translated into service discovery information, the MMT control message may include an information table for service discovery.

The server dividing the multimedia content into a plurality of segments allocates URL information to a plurality of segments divided into a predetermined number, and stores URL information about each segment in a media information file and transmits the URL information to the client.

The media information file may be called various names such as "media presentation description (MPD)" or "manifest file" according to a standardization organization that standardizes HTTP streaming. Hereinafter, the media information file is referred to and described as a media presentation description (MPD).

The cross-layer interface is described below.

The Cross Layer Interface (CLI) provides a means for supporting QoS in a single MMT entity by exchanging QoS related information between lower layers including the application layer and the MAC / PHY layer. The lower layer provides bottom-up QoS information such as network channel status, while the application layer provides information related to media characteristics as top-down QoS information.

The cross layer interface provides an integrated interface between the application layer and various network layers including IEE802.11 WiFi, IEEE 802.16 WiMAX, 3G, 4G LTE, etc. Common network parameters of popular network standards are extracted as NAM (Network Abstraction for Media) parameters for static and dynamic QoS control of real-time media applications over various networks.

In the cross-layer interface, the application layer provides top-down QoS information related to media characteristics for lower layers. There are two types of top-down information such as MMT asset level information and packet level information. MMT asset information is used for capacity exchange and / or resource (re) allocation at lower layers. Packet level top down information is recorded in the appropriate field of every packet for the lower layer to identify the QoS level it supports.

In addition, in the cross layer interface, the lower layer provides bottom-up QoS information to the application layer. The lower layer provides information regarding network conditions that change over time, enabling faster and more accurate QoS control at the application layer. Bottom-up information is expressed in an abstracted form to support heterogeneous network environments. These parameters are measured at the lower layer and read at the application layer periodically or at the request of the MMT application.

4 illustrates a problem that occurs when using a packet error rate (PER) for rate adaptation. The PER drops the entire packet if there is more than one bit error, regardless of the amount of bit errors, so it is impossible to determine exactly how many errors were in the packet.

Referring to FIG. 4, a problem occurring when using a packet error rate (PER) for rate adaptation will be described. Case 1 of FIG. 4 illustrates a situation in which fewer corrupted bits are included in a packet than Case 2. FIG. Therefore, Case 1 has a lower bit error rate (BER) than Case 2, and thus shows a better channel environment (lower BER) than Case 2. In these two situations (Case 1 and Case 2), when using PER, Case 1 and Case 2 are regarded as the same channel and used for rate adaptation. Therefore, in terms of PER, Case 1 and Case 2 of FIG. 4 are determined to be in the same channel condition.

FIG. 5 is a conceptual diagram comparing case of using PER and rate of BER in case 1 of FIG. 4 in terms of throughput. An example of two codewords is shown in FIG. The first codeword 510 is a codeword when channel coding (block coding) using PER, and the second codeword 520 is a codeword when channel coding (block coding) using BER. to be. In the case of the first codeword 510, the ratio of the redundant bit r 511 in the codeword is close to 50%. However, in the case of the second codeword 520, the ratio of the redundant bit r 521 in the codeword is only about 20%. That is, when channel coding (block coding) Case 1 using PER as shown in the first codeword 510, an unnecessary number of redundant bits r are used to estimate a channel using BER. This can lead to less efficiency when channel coding. In conclusion, in case of using BER (case 1 of FIG. 4), throughput improvement can be obtained compared to using PER.

Accordingly, rate adaptation using BER enables efficient multimedia transmission. BER can be estimated using the signal strength and modulation information (FIGS. 7 to 9) in the MAC (Media Access Control) layer, and message standardization as shown in any one of Tables 1, 2, and 3 below. Can be used interchangeably on different wireless networks. In the MAC layer, when the MAC packet is received, the BER is estimated using information on a modulation scheme, signal strength, and surrounding wireless traffic. (The BER value is slightly less accurate than the PHY layer). In the physical layer, error checking is possible in units of bits, so accurate BER value estimation is possible.

Example 1

Table 1

According to an embodiment of the present invention, the bit error rate is obtained at the PHY or MAC layer using a BER variable (or parameter). For BER in the PHY layer, the BER value is presented as a positive value. For BER in the MAC layer, the BER value is presented as a negative value that can be used as an absolute value. That is, the most significant bit (MSB) of the BER is a flag indicating a PHY or MAC layer.

Example 2

TABLE 2

According to another embodiment of the present invention, after estimating the BER in the PHY layer or the MAC layer, the BER variable (or parameter) can be delivered to the upper layer. The type variable (or parameter) is used to indicate whether the bit error rate is obtained from the PHY layer or the MAC layer.

In the physical layer, error checking is possible in units of bits, so accurate BER value estimation is possible. In the MAC layer, when the MAC packet is received, the BER is estimated using information on a modulation scheme, signal strength, and surrounding wireless traffic. (The BER value is slightly less accurate than the PHY layer). The TYPE field specifies on which layer the BER is delivered.

Example 3

TABLE 3

Hereinafter, an example of using the BER parameter in the NAM parameter in the cross-layer interface of the multimedia system using the BER according to an embodiment of the present invention will be described. In the cross layer interface, the NAM parameter may be used as an interface between the application layer and the lower layer. The NAM parameter may include a BER value that is a bit error rate. BER can be measured at the PHY or MAC layer. The NAM also provides the identification of the underlying network, possible bit rates, buffer conditions, peak bit rates, service unit sizes, and service data unit loss rates.

Two different methods can be used to provide the NAM. One way is to provide an absolute value. Absolute NAM information is the QOS value as measured in each unit. And another way is to provide relative values. Table 4 below shows the syntax of the absolute NAM parameter.

Table 4

CLI_id is an arbitrary integer that allows the underlying network to identify the NAM. Bit Error Rate (BER) is the last measured bit error rate in the PHY or MAC layer. The BER measured at the PHY layer is provided as a positive value. The BER measured in the MAC layer is provided as a negative value, and in actual use, an absolute value is used.

Relative NAM information is expressed as the ratio of the current NAM value to the expected NAM value. For example, it may be expressed as the ratio of the expected NAM value to the current NAM value, or alternatively it may be expressed as the ratio of the current NAM value to the expected NAM value. The method of providing relative NAM information may be used to update the NAM during the connection, or may be used to inform the trend of QOS environment changes. Table 5 below shows the syntax of relative NAM parameters.

Table 5

CLI_id is an arbitrary integer that allows the underlying network to identify the NAM. Bit Error Rate (BER) is the last measured bit error rate in the PHY or MAC layer. The BER measured at the PHY layer is provided as a positive value. The BER measured in the MAC layer is provided as a negative value, and in actual use, an absolute value is used.

In addition, the BER may be used for a Network Aware Media Feedback (NAMF) message among messages related to package delivery. NAMF is a form of NAM parameter report that is fed back from the receiver to the transmitter. Table 6 below shows the syntax of the NAM feedback.

Table 6

Here, message_id represents the ID of the NAM feedback message. For example, Message_id may have a total length of 16 bits. CLI_id is an arbitrary integer for identifying a specific NAM in a lower network. BER is a value generated at the PHY or MAC layer, BER generated at the PHY layer has a positive value, BER generated at the MAC layer has a negative value, and an absolute value is used when using the value. do. As shown in Table 6, the BER parameter may be fed back from the receiver to the transmitter in the form of being inserted into the payload of the NAM_Feddback_message.

6 is a block diagram of a multimedia system using BER according to an embodiment of the present invention. Referring to FIG. 6, a multimedia system using a BER according to an embodiment of the present invention includes a transmitter 650, a receiver 600, and a wireless network device such as an AP. In one embodiment, the transmitter 650 may be a server and the receiver 600 may be a client.

The transmitter 650 includes a video encoder 653, a forward error correction (FEC) encoder 654, a rate tuner 652, and a transmitter. The video encoder 653 and the FEC encoder 654 form an encoder unit 655, which corresponds to a media data generator that generates media data to be transmitted.

The video encoder 653 performs channel coding on an MMT transport packet block including at least one MMT transport packet or an MMT packet block including at least one MMT packet to transmit an MMT transport packet or an MMT packet. In addition, the FEC encoder 654 performs FEC encoding on the generated symbol block and transmits the generated video stream to the transmitter.

The rate tuner 652 receives the feedback information 603 received from the receiver 600 and controls the operation of the encoder 655. For example, the rate tuner 652 may select the channel coding rate of the encoder unit 655 by performing rate control of the video stream according to the channel condition.

The feedback information 603 received from the receiver includes the estimated BER value and information of the layer where the BER is estimated, so that the rate tuner 652 estimates the channel state by using the BER value and the information of the estimated layer. The operation may be controlled by controlling the channel coding rate of the encoder 655.

In another embodiment, the rate tuner 652 is an encoder unit 655 using channel state information included in the feedback information 630 estimated by the receiver 600 using the BER value and the information of the BER estimated layer. ) Can also be controlled.

The encoder 655 codes the channel at a coding rate under the control of the rate tuner 652 and transmits a video stream to the receiver 600. More specifically, the encoder unit 655 transmits the video stream generated by channel coding the MMT transport packet to the transmission unit according to the coding rate, the transmission unit delivers the video stream to the AP through a wired network, and the AP transmits the wireless network. The video stream is transmitted to the receiver 600 through a wireless network 601.

Side information 602 may be generated while the transmitting device 650 transmits the video stream to the receiving device 600. In this case, the additional information may include only additional information occurring on the wireless network. For example, the additional information may include signal strength, modulation information, and ambient wireless traffic information. The receiver of the receiver 600 may receive additional information 602 together with the video stream.

The receiver 600 includes a channel estimator 610, an FEC decoder 622, a video decoder 624, and a receiver. The FEC decoder 622 and the video decoder 624 constitute a decoder 620. The FEC decoder 622 generates a symbol block by performing FEC decoding on the received video stream, and the video decoder 624 performs video decoding on the generated symbol block to generate an MMT transport packet block or an MMT packet block. Generate a transport packet or an MMT packet.

 The channel estimator 610 estimates a channel state using the estimated BER value using side information 602 obtained through the receiver, and generates the estimated channel state as channel state information. The channel state estimator may transmit the generated channel state information to the decoder 620 or the application layer, and may use a cross-layer interface of the MMT system. That is, the channel state estimator may transfer the generated channel state information to another layer using the NAM parameter. For example, the estimated BER parameter may be included in the NAM parameter and delivered to the application layer. In addition, the channel state estimator 610 may transmit the generated channel state information to the rate tuner 652 of the transmitter 650.

In another embodiment, the channel state estimator may transmit the BER value estimated in one of the PHY layer and the MAC layer to another layer or the transmitter 650 together with an indicator indicating the layer where the BER value is estimated. have. When the channel state estimator 610 delivers the BER value to another layer with an indicator indicating the estimated layer, the cross layer interface may be used. In this case, the channel state estimator 610 may include the BER parameter in the NAM parameter and transmit the BER value to another layer. .

When the channel state estimator 610 feeds back the BER value to the transmitter 650 together with an indicator indicating the estimated layer, the BER parameter may be included in the NAMF parameter and transmitted to the transmitter 650.

10 to 11 are flowcharts illustrating rate adaptation in a wireless network according to an embodiment of the present invention. Hereinafter, a process of performing rate adaptation in a multimedia system using BER according to an embodiment of the present invention will be described with reference to FIGS. 10 to 11.

First, a client, which is a receiver 600, estimates a BER using additional information about a received packet (S1001). This may be performed by the client receiving the BER estimated from the PHY layer or the MAC layer as shown in FIG. 11 (S1101). Next, the client estimates the channel capacity of the wireless network by using the estimated BER (S1003). In operation S1005, the estimated channel capacity is transmitted to the server that is the transmission device 650. The server predicts the channel capacity using the fed back channel capacity estimate (S1007). The video / channel coding rate is optimally adjusted based on the predicted channel capacity (S1009). Finally, the server transmits the video coding and channel coding to the client by using the adjusted coding rate (S1011).

7 to 9 illustrate BER estimation according to signal strength (SNR) and modulation scheme in different wireless networks (MAC layer). FIG. 7 is a graph showing the correlation between BER and signal to noise ratio (SNR) in an 802.11a wireless network, and FIG. 8 is a graph showing the correlation between BER and signal to noise ratio (SNR) in an 802.11g wireless network. 9 is a graph showing the correlation between BER and signal to noise ratio (SNR) of a WiMax wireless network. The BER estimate delivered by the MAC or physical (PHY) layer can predict the optimal video / channel coding rate or the optimal source / channel coding rate by the following method.

Equation 1

Referring to Equation 1, Q (.) Is a rate distortion (RD) function of a video, and the RD function can be obtained during video encoding.

Q '(.) Is a video quality distortion estimation function that differs beyond the channel capacity. Q '(.) Uses f (x) = ax ^b + c, 0 ≦ x ≦ 0.12. a = -1.18 × 10 ² ; b = 2.148; And c = 0.9898. The values are obtained through experiment. Accordingly, the numerical value may change depending on the video data, but there are not many errors. In particular, an accurate value may be predicted when the values are substituted with zero. x is the difference between the rate to be predicted and the channel capacity (i.e.

)to be. In other words, the larger the difference, the larger the distortion of the video quality. Where the Gaussian distribution is the prediction error probability distribution. Therefore, the optimum rate in Equation 1 is a value when the combination of Q (.), Q '(.) And rate prediction error expansion rule distribution becomes the best. For a detailed process of obtaining an optimal video / channel coding rate or an optimal source / channel coding rate using Equation 1, refer to the previously published Korean Patent Application Publication No. 10-2009-0071005.

The server 150 may apply the differential rate according to the characteristics of the video frame using the LDPC code when the channel coding. The performance of the LDPC code varies depending on the length of the packet and the value of α (see below) (see FIG. 9). In addition, encoded video frames differ in importance depending on the type. That is, if there is no I frame, the P or B frame cannot be decoded. Therefore, a packet including an I frame (each packet has a different length) performs channel coding by applying a value of α which is sure to be decoded in the client terminal 100 (i.e., by providing more redundant bits to give more error to the error). Harden). For example, in the case of an I frame packet having a length of 800 bits, channel coding may be performed by applying an α value of 2.7.

After channel coding of the I-frame packet, the P frame packet is channel coded by applying an α value according to Equation 2 below (see Equation 4).

Equation 2

On the other hand, R ^OP in Equation 1 represents an operational rate (operational rate). All existing channel codes are inferior to channel capacity. Therefore, there is a performance decrease depending on the performance of the channel code, which applies an α value as shown in Equation 3 below. Α is 1 for an ideal channel code. Α is usually at least about 2.0.

Equation 3

Meanwhile, a total redundant bit is calculated using Equation 1, which may be rearranged as follows.

Equation 4

The video quality result (ORPA _CLDS ) in the terminal utilizing the present invention is shown in Table 3 below. ORPA _CON represents the performance of the current 802.11b protocol. According to the present invention, video quality of up to 6 dB or more can be improved.

TABLE 7

Table 7 shows Rate adaptation performance comparison in terms of video quality in dB.

In Table 7, Xmit Rate refers to the transmission rate of video data, Operation channel represents the maximum PSNR realistically possible when transmitting video data, and ORPA _CLDS includes additional signal strength information according to an embodiment of the present invention. The performance when the protocol for estimating the channel state using the information is applied, and the ORPA _CON indicates the performance when the conventional WLAN 802.11b protocol is applied (here, ORPA means Optimal Rate Prediction Architecture). Referring to Table 7, when the physical data rate is low (2 or 5.5 Mbps), referring to the performance of the average transmission rate (avg) of Table 3, the performance of the conventional ORPA _CON (30.63 dB, 29.75 dB) compared to the performance of the ORPA _CLDS (30.69 dB, 30.11 dB) according to an embodiment of the present invention, but when the physical data rate is 11 Mbps, the average transmission rate of Table 1 ( avg), the performance of the ORPA _CLDS according to the embodiment of the present invention (23.28 dB) compared to the performance of the conventional ORPA _CON (a. Can be.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited thereto. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims (20)

1. Generating a message including an indicator indicating a layer in which a bit error rate is generated among a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer. How to receive multimedia.
2. The method of claim 1,

   The message further includes a parameter indicative of the bit error rate;

   And an indicator indicating a layer in which the bit error rate is generated belongs to a part of a parameter representing the bit error rate.
3. The method of claim 2,

   An indicator indicating the layer at which the bit error rate was generated and transmitting the generated bit error rate to a transmitting device, or channel state, wherein the channel state is an indicator indicating the layer at which the bit error rate was generated and the bit error rate. Generated using-transmitting to the transmitting device.
4. The method of claim 1,

   And an indicator indicating a layer in which the bit error rate is generated is transmitted between layers of a receiving apparatus through a cross layer interface (CLI).
5. Using a bit error rate comprising receiving a message including an indicator indicating a layer from which a bit error rate is generated among a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer Multimedia transmission method.
6. The method of claim 5,

   And the bit error rate is estimated and generated by using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.
7. The method of claim 5,

   Receiving a Media Fragment Unit (MFU) having a format independent of a specific media codec from a media codec layer;

   Generating a Media Processing Unit (MPU) using the media fragment unit;

   Encapsulating the generated media processing unit to generate an MMT asset;

   Generating an MMT package by encapsulating the generated MMT asset;

   Receiving the generated MMT package and generating an MMT payload; And

   And generating an MMT transport packet using the generated MMT payload.
8. The method of claim 5,

   And selecting a coding rate by performing a rate control of media data to be transmitted based on the bit error rate in the generated message.
9. The method of claim 6,

   The additional information includes at least one of signal strength, modulation information, and surrounding wireless traffic information.
10. In the method for estimating the channel state using the bit error rate,

    Generating the bit error rate by using additional information among a plurality of different layers including at least one of a physical layer and a MAC layer; and

    And including the generated bit error rate and an indicator of a layer in which the bit error rate is generated and transmitting the message to another layer.
11. A bit error rate (BER) generation unit generating a message including an indicator indicating a layer in which a bit error rate is generated among a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer. Multimedia receiving apparatus using a bit error rate, characterized in that it comprises a.
12. The method of claim 11,

    And a channel estimator configured to receive a bit error rate and information on the layer in which the bit error rate is generated from the BER generator and estimate a channel state.
13. The method of claim 11,

    The message further includes a parameter indicative of the bit error rate;

    And an indicator indicating a layer in which the bit error rate is generated belongs to a part of a parameter representing the bit error rate.
14. The method of claim 11,

    And an indicator indicating the layer in which the bit error rate is generated has a value of 0 when the layer in which the bit error rate is generated is a physical layer.
15. A media data generator for generating media data to be transmitted;

    A transmitter for transmitting the media data generated by the media data generator; And

    And a rate tuner for controlling the operation of the media data generator according to the channel information received from the receiver.

    The channel information is a message including an indicator indicating a layer in which a bit error rate is generated among a plurality of different layers of the receiving apparatus including at least one of a physical (PHY) layer and a media access control (MAC) layer. Multimedia transmission apparatus using a bit error rate, characterized in that the channel state information generated by the receiving apparatus using.
16. The method of claim 15,

    And the bit error rate is estimated and generated using additional information in a plurality of different layers including at least one of a physical (PHY) layer and a media access control (MAC) layer.
17. The method of claim 15,

    A media fragment generation unit receiving a media fragment unit (MFU) having a format independent of a specific media codec from a media codec layer;

    A media processing unit generation unit generating a media processing unit (MPU) using the media fragment unit;

    An MMT asset generator for generating an MMT asset by encapsulating the generated media processing unit;

    An MMT package generator for generating an MMT package by encapsulating the generated MMT asset;

    An MMT payload generator configured to receive the generated MMT package and generate an MMT payload; And

    Further comprising an MMT transport packet generation unit for generating an MMT transport packet using the generated MMT payload,

    The media data generator generates the media data to be transmitted by channel coding the MMT transport packet generated by the MMT transport packet generator.
18. The apparatus of claim 15, wherein the rate tuner selects a coding rate by performing rate control of the media data based on the received channel information.
19. The method of claim 18,

    The media data generator generates the media data by coding a channel at the coding rate,

    And the transmitting unit transmits the media data to a client.
20. An apparatus for estimating a channel state using a bit error rate,

    A BER generator for generating the bit error rate by using additional information among a plurality of different layers including at least one of a physical layer and a MAC layer; And

    And an interlayer transmission unit including the measured bit error rate and an indicator of a layer in which the bit error rate is generated and transmitting the same to another layer.

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