KR20030060027A - A Method for transmitting a packet data in the High Speed Downlink Packet Access system - Google Patents

Abstract

PURPOSE: A method for transmitting packet data in an HSDPA(High Speed Downlink Packet Access) system is provided to enable a scheduler, located at a base station, to receive control information related to data transmission from an upper layer so as to ensure transmission quality suitable for the characteristics and requirements of each service and, based on this, to efficiently distribute radio resources in consideration of information related to data delay time. CONSTITUTION: MAC-hs SDUs and scheduling control information related to them are stored in a storage unit(201) and a control information management unit(209) respectively. A scheduler(207) receives buffer status information from the storage unit(201) together with scheduling control information related to the delay time of each data(S212). Besides the scheduler(207) receives channel status information from a physical layer(205)(S213). Based on the buffer status information and the channel status information, the scheduler(207) executes scheduling for data transmission control and determines the size of a data block and MAC-hs SDUs to transmit. Then the scheduler(207) adds a priority class identifier and a TSN(Transmission Sequence Number) to the transmission-determined data block and transfers it to a HARQ(Hybrid Automatic Repeat reQuest) block(203). The transferred data block is transmitted through the physical layer(205)(S214,S215). At this moment, if a transmission result that a specific data block has been transmitted successfully is received from the HARQ block(S216), the storage unit(201) deletes the associated data together with scheduling control information associated with the data.

Description

A method for transmitting a packet data in the High Speed Downlink Packet Access system}

The present invention is a high speed downlink packet access: relates to an operation of the (HSDPA High Speed Downlink Packet Access) base station packet transfer coordinator (hereinafter referred to as the scheduler) in order to ensure the quality of the multimedia communication service in a mobile communication system that supports, in particular Considering the information related to the delay time of the scheduler during the operation of the scheduler, it is possible to schedule not only the priority of the data but also the delay time of the data according to the characteristics of the service, so that the mobile communication user can access the multimedia service through the HSDPA system. In the case of receiving the data, it is to be able to receive data by an appropriate scheduling method.

UMTS (Universal Mobile Terrestrial System (UMTS)) is a third generation mobile communication system (usually IMT) that has evolved from the European standard Global System for Mobile Communications (GSM) system. -2000, based on the GSM Core Network and Wideband Code Division Multiple Access (WCDMA) wireless access technology, aims to provide more advanced mobile communication services.

For the standardization work of UMTS, in December 1998, regional standardization bodies such as ETSI in Europe, ARIB / TTC in Japan, T1 in the US and TTA in Korea were proposed to propose the IMT-2000 standard to the International Telecommunication Union (ITU). A combination called the Third Generation Partnership Project (hereinafter abbreviated as 3GPP) has been formed and a detailed specification of UMTS is being prepared.

The 3GPP is divided into five Technical Specification Groups (hereinafter, abbreviated as TSG) in consideration of the independence of network components and their operation in order to develop UMTS quickly and efficiently.

Each TSG is responsible for the development, approval, and management of standards within the relevant areas, among which the Radio Access Network (hereinafter referred to as RAN) group (TSG-RAN) is the WCDMA access technology in UMTS. To develop a specification for the functions, requirements, speed, and interface of the UMTS radio network (hereinafter referred to as UTRAN), which is a new radio access network for supporting technology.

The TSG-RAN Group is again composed of a Plenary Group and four Working Groups.

Working Group 1 (WG1) develops standards for the Physical Layer (WG1), while the second Working Group (WG2) works with the Data Link Layer (2nd Layer) and Network Layer (WG2). Role of the third tier).

In addition, the third operation group defines standards for interfaces between base stations, radio network controllers (hereinafter referred to as RNCs) and core networks in the UTRAN, and the fourth operation group relates to radio link performance. Discuss requirements and requirements for radio resource management.

1 is a diagram showing the structure of a 3GPP UTRAN to which the prior art and the present invention is applied.

Referring to FIG. 1, the UTRAN 110 includes one or more Radio Network Sub-systems (hereinafter referred to as RNS) 120 and 130, and each RNS 120 and 130 is connected to one RNC 121 and 131. It consists of one or more base stations (Node Bs) 122, 123, 132, 133 managed by the RNC 121, 131.

The RNC 121 and 131 are connected to a mobile switching center (MSC) 141 for circuit switched communication with a GSM network, and SGSN for packet switched communication with a general packet radio service (GPRS) network. (Serving GPRS Support Node) 142.

The base station (Node B) 122, 123, 132, 133 is managed by the RNC (121, 131), and receives the information sent from the physical layer of the terminal 150 in the uplink, and the terminal 150 in the downlink Send to

Therefore, the base station Node B may be regarded as playing an access point of the UTRAN to the terminal.

The RNCs 121 and 131 are in charge of allocating and managing radio resources. The RNC responsible for the direct management of the base station Node B is called a Control RNC (CRNC), and is responsible for the management of common wireless resources.

In addition, a place that manages dedicated radio resources allocated to each terminal is called a serving RNC (SRNC). The control RNC and the responsible RNC may be the same, but when the terminal moves out of the area of the responsible RNC to the area of another RNC, the control RNC and the responsible RNC may be different.

Since various components in the UMTS network may have different physical locations, an interface is required to connect them. The base station Node B and the RNC are connected by an Iub interface, and the two RNCs are connected through an Iur interface. The interface between the RNC and the core network is called Iu.

2 illustrates a hierarchical structure of an interface protocol that enables wireless access between a UE and a UTRAN based on the 3GPP radio access network standard.

The wireless access interface protocol of FIG. 2 consists of a physical layer (PHY), a data link layer, and a network layer horizontally, and vertically controls a control plane for transmitting control signals and a data plane for transmitting data information. It is divided into user planes.

The user plane is an area in which user traffic information is transmitted, such as voice or IP packet transmission, and the control plane is an area in which control information necessary for maintaining and managing an interface or a call of a network is transmitted.

The protocol layers of FIG. 2 are based on the lower three layers of the Open System Interface (OSI) reference model, which are well known in communication systems. The first layer (L1), the second layer (L2), and the third layer (L3).

The first layer L1 performs a role of a physical layer (PHY) for the wireless interface, and a transport channel with a medium access control layer (hereinafter abbreviated as MAC) layer on the upper layer. Are connected via

Data transmitted to the physical layer through a transport channel is transmitted to a receiver by using various coding and modulation methods suitable for a wireless environment.

The transport channel existing between the physical layer and the MAC layer is a dedicated transport channel and a common transport channel, respectively, depending on whether the terminal can be used exclusively or shared by multiple terminals. Are distinguished.

The second layer L2 plays a role of a data link layer and enables multiple terminals to share radio resources of a UMTS network.

The second layer (L2) is the MAC layer, Radio Link Control (hereinafter referred to as RLC) layer, Packet Data Convergence Protocol (hereinafter referred to as PDCP) layer, and broadcast / multicast control (Broadcast / Multicast Control; hereinafter abbreviated as BMC) is divided into layers.

Here, the MAC layer transfers data using an appropriate mapping relationship between logical channels and transport channels. Logical channels are provided with various logical channels according to the type of information transmitted to the channels connecting the upper layer and the MAC layer.

In general, a control channel is used to transmit control plane information, and a traffic channel is used to transmit information of the user plane.

The MAC layer is divided into two sublayers according to the function performed again.

These are the MAC-d sublayer located in the SRNC while managing the dedicated transport channel, and the MAC-c / sh sublayer located in the CRNC while managing the common transport channel.

The RLC layer configures an appropriate RLC PDU suitable for transmission by a segmentation and concatenation function of an RLC SDU transmitted from an upper layer, and performs an automatic repeat request for retransmission of the lost RLC PDU during transmission; ARQ) function can be performed.

The RLC SDU or RLC descended from the upper layer operates in three ways: transparent mode, unacknowledged mode, and acknowledgment mode, depending on the method of processing the RLC SDU from the upper layer. There is an RLC buffer for storing PDUs.

The PDCP layer is located on top of the RLC layer, making it suitable for data transmitted through a network interface such as IPv4 or IPv6.

In particular, in the PDCP layer, a header compression technique of compressing and transmitting header information of a packet may be used for efficient transmission of an IP packet.

The BMC layer enables a message transmitted from a cell broadcast center (CBS) to be transmitted through an air interface.

The main function of the BMC is to schedule and transmit a cell broadcast message transmitted to a terminal, and generally transmits data through an RLC layer operating in an unresponsive mode.

For reference, since the PDCP layer and the BMC layer transmit only user data, they are located only in the user plane.

Unlike these, the RLC layer may belong to the user plane or to the control plane depending on the layers connected to the upper layer. In the case of belonging to the control plane corresponds to the case of receiving data from the radio resource control (hereinafter referred to as RRC) layer, otherwise it corresponds to the user plane.

As shown in FIG. 2, in the case of the RLC layer and the PDCP layer, several entities may exist in one layer. This is because one terminal has several radio carriers, and generally only one RLC entity and PDCP entity are used for one radio carrier. Entities of the RLC layer and the PDCP layer may perform independent functions in each layer.

An important concept used in UMTS is a radio bearer (RB), which generally means a transmission service of user data provided to a higher layer by a second layer L2 in a user plane.

In addition, the control information transmission service provided to the upper layer by the second layer (L2) in the control plane is defined as a signaling radio bearer (SRB).

The RRC layer located at the bottom of the third layer L3 is defined only in the control plane, and is responsible for control of transport channels and physical channels in connection with setting, resetting, and releasing radio carriers.

In this case, the setting of the wireless carrier means a process of defining characteristics of a protocol layer and a channel necessary to provide a specific service and setting each specific parameter and operation method. It is also possible to transmit control messages transmitted from the top of the RRC layer through the RRC message.

The UMTS described above aims at a transmission rate of 2Mbps in indoor and pico-cell environments and 384kbps in a general wireless environment. However, as the wireless Internet becomes more common and the number of subscribers increases, more various services are emerging, and it is expected that a system having a higher transmission speed is required to support these services.

Therefore, in 3GPP, research is being conducted to provide a high transmission rate by evolving a UMTS network. Among them, a representative system is HSDPA (High Speed Downlink Packet Access).

Based on UMTS technology, HSDPA system is expected to support up to 10Mbps speed in downlink and provide shorter packet transmission delay and improved capacity.

The techniques employed in the HSDPA system to provide improved transmission rates and capacities include Link Adaptation (LA), Hybrid Automatic Repeat Request (HARQ), and fast cell selection. Fast Cell Selection (hereinafter referred to as FCS), and Multiple Input Multiple Output (hereinafter referred to as MIMO) antenna techniques.

The link adaptation technique (LA) uses a modulation and coding scheme (hereinafter referred to as MCS) that is adapted to the state of the channel. If the channel state is good, a high modulation such as 16QAM and 64QAM is used. In case the channel condition is not good, a low modulation method such as QPSK is used.

In general, the low-modulation method has a smaller amount of transmission than the high-modulation method. However, when the channel environment is not good, the low modulation method has an excellent transmission success rate. Therefore, it may be considered to be advantageous when the influence of fading or interference is large. .

On the other hand, high modulation methods have much higher frequency utilization efficiency than low modulation methods, and can provide a transmission rate of 10Mbps using the 5MHz bandwidth of WCDMA. However, it is very sensitive to the effects of noise and interference.

Therefore, when the terminal is located close to the base station, it is possible to increase the transmission efficiency by using 16QAM or 64QAM, and when the terminal is located at the cell boundary or the influence of fading is low, a low modulation method such as QPSK is useful. Do.

The HARQ method is a retransmission method having a different concept from that of a packet retransmission performed in the RLC layer. This ensures higher recovery rates by combining data that has been used and retransmitted in conjunction with the physical layer with previously received data.

That is, a method of recovering a packet by combining a retransmitted packet with a pre-decoding step while storing the packet that failed to be transmitted without discarding it. Therefore, when used together with the LA technique, the packet transmission efficiency can be greatly increased.

The FCS method is similar to the conventional soft handover. Although the terminal may receive data from multiple cells, the terminal may receive data from a cell having the best channel state in consideration of the channel state of each cell.

Conventional soft handover has been a method of receiving data from multiple cells and increasing the transmission success rate using diversity, but the FCS method receives data from only one specific cell in order to reduce interference between cells.

MIMO antenna technique is a method that can improve the success rate of data recovery by using multiple propagation having independent characteristics in the channel environment where scattering occurs a lot.

It is usually composed of several transmitting antennas and several receiving antennas, and it is a system to obtain diversity gain by reducing the correlation between radio waves received for each antenna.

On the other hand, the HSDPA system intends to introduce a new technology while maintaining the existing UMTS network as possible in order to maintain compatibility with the conventional system and to reduce additional costs due to the deployment of the network.

However, some modifications are inevitable to incorporate new technologies. The biggest change is the improvement of the existing base station (Node B) function.

That is, in the UMTS network, most of the control functions are located in the RNC, but the function of the base station Node B is improved in order to adapt to the channel situation more quickly and reduce the delay time to the RNC. Therefore, most of the new technologies for the HSDPA system are managed by the base station.

However, the extended function of the base station (Node B) is not a function of replacing the RNC, and in view of the RNC, it can be seen that it is in charge of an auxiliary function in which functions for high speed data transmission are added to the base station managed by the base station.

Therefore, unlike the existing WCDMA system, the base station Node B has been modified to perform a part of the MAC function, and a layer for performing this is called a MAC-hs sublayer.

The MAC-hs sublayer may be located above the physical layer to perform packet scheduling or HARQ and LA functions. In addition, a transport channel called HS-DSCH (High-Speed Downlink Shared Channel), which is different from the existing transport channel, is used for data transmission for HSDPA. This channel is used to transmit data from the MAC-hs sublayer of the base station Node B to the physical layer.

3 shows the structure of a radio access protocol for supporting the HSDPA system. The MAC-hs sublayer is located above the physical layer (PHY) of the base station (Node B), and the MAC-c / sh and MAC-d sublayers are located in the CRNC and the SRNC, respectively, as in the conventional system.

A transport protocol called HS-DSCH FP (Frame Protocol) is used for the transmission of data for HSDPA on the Iub or Iur interface. In this case, the MAC-c / sh sublayer, the MAC-d sublayer, and the RLC layer located above the MAC-hs sublayer perform the same functions as the current system.

Therefore, the RNC to support HSDPA is enough to add only a little software in the current system.

The structure of the MAC layer used in the HSDPA system is shown in detail in FIG. 4.

As shown in FIG. 4, the MAC layer is divided into three sublayers: the MAC-d sublayer 161, the MAC-c / sh sublayer 162, and the MAC-hs sublayer 163. The MAC-d sublayer 161 manages dedicated logical channels for a specific terminal while in the SRNC, and the MAC-c / sh sublayer 162 manages common transport channels located in the CRNC and the MAC-hs sublayer 163 is located in the base station (Node B) to manage the HS-DSCH.

However, it can be said that there is almost no function performed by the MAC-c / sh sublayer 162 in the HSDPA system. That is, the MAC-c / sh sublayer 162 has been responsible for allocating and processing common resources shared by multiple terminals in the existing system. However, in the HSDPA system, the MAC-c / sh sublayer 162 is simply transferred from the MAC-d sublayer of SRNC. It performs only a flow control role of delivering the data to the MAC-hs sublayer 163 of the base station Node B.

Referring to FIG. 4, flow control, HARQ, scheduling, and TFC selection, which are functions performed in the MAC-hs sublayer, will be described.

The flow control function controls the flow of data in consideration of the transmission capability of the interface of the network. This function is used to prevent the discard of data that may be caused by congestion on the interface when data is transmitted through the HS-DSCH or to reduce the delay time of the signaling signal in the second layer (L2).

In this case, flow control may be independently performed for each priority of data transmitted through each HS-DSCH channel.

As described briefly above, the HARQ function is a method used to increase data transmission efficiency. In order to support the HARQ function, a HARQ block exists in the MAC-hs sublayer 163 of the base station. In the HARQ block, there is an HARQ entity that manages HARQ operation of each terminal, and one HARQ entity exists for each terminal.

In addition, several HARQ processes exist within each HARQ entity, and each HARQ process is used for transmission of specific data.

Each HARQ process can share and use multiple data, but are processed one at a time. Therefore, if the data transmission is successful, it becomes an empty process and can be used to transfer other data. If the data transmission fails, the data is stored until the data is successfully transmitted or discarded.

Data transmitted by each HARQ process is called a data block, and the data block is composed of one or several MAC-hs SDUs. For reference, the size of each MAC-hs SDU is not variable and has a fixed size. The number of MAC-hs SDUs constituting the data block may vary depending on the state of the radio channel. That is, because a good channel can transmit a large amount of data, as many MAC-hs SDUs are included.

In contrast, when the channel is in poor condition, a relatively small number of MAC-hs SDUs constitute a data block. The size of the data block is determined by a scheduling block that receives a report on the channel state from the physical layer.

At this time, the transmission of each data block is periodically transmitted in a unit called a transmission time interval (TTI), usually TTI is composed of a unit of 2ms.

The scheduling function of the base station determines the transmission order of the data according to the priority of the data to be transmitted. In addition, the size of the data block to be processed in the HARQ process is determined, and the priority class identifier (ID) and serial number (transmission sequence number (hereinafter abbreviated as TSN)) of the block are attached to the appropriate HARQ process. . If the data block fails to be retransmitted, the same data block previously transmitted is retransmitted.

The TFC selection function plays a role of informing a transport format of each HS-DSCH when several HS-DSCHs are used for data transmission.

Referring to FIG. 4, let's see how the data from the RLC layer is transferred to the HS-DSCH in the MAC layer. The RLC PDUs transmitted from the RLC layer through a dedicated traffic channel (DTCH) or a dedicated control channel (DCCH) are routed through a channel switching function in the MAC-d layer.

When transmitted on a dedicated channel (DCH: Dedicated Channel), the relevant header is attached to the MAC-d sublayer 161 and transferred to the physical layer through a dedicated channel (DCH), and the HS-DSCH channel of the HSDPA system is used. If so, the RLC PDU is transmitted to the MAC-c / sh sublayer 162 through transport channel multiplexing by a channel switching function.

Transport channel multiplexing adds identification information of a logical channel to which each data belongs when several logical channels use one transport channel. The MAC-c / sh sublayer 162 receiving the RLC PDU simply transfers a packet from the MAC-d sublayer 161 to the MAC-hs sublayer 163. Data delivered to MAC-hs sublayer is stored in buffer of MAC-hs sublayer 163 and is composed of data block of appropriate size for channel status by scheduling function, and priority information and TSN are added to the data block. It is then delivered to the HARQ process at the appropriate time.

At the time of transmission, a TFC (Transport Format Combination) suitable for the transmission format of the HS-DSCH is selected and transmitted.

FIG. 5 illustrates an operation of a scheduling block in the MAC-hs sublayer. The configuration and operation of the scheduling block will be described.

Referring to FIG. 5, the scheduler 174 receives information such as priority and data amount of stored data from the storage device 171 (S101), and receives channel state information from the physical layer 173 (S101). S102).

In this case, the storage device 171 generally corresponds to a soft memory that can easily erase and write data, and stores MAC-hs SDUs transmitted from an upper layer. The scheduler 174 controls the operations of the storage device 171 and the HARQ entity 172 based on these information (S103, S104).

That is, the scheduler 174 determines the size of the data block to be transmitted and the MAC-hs SDUs to be included in the data block, adds a priority identifier and a TSN to the data block, and transfers it to the appropriate HARQ process of the selected HARQ entity through the physical layer. To be transmitted.

When the data block is successfully transmitted in the HARQ block 172, identification information about the corresponding data is transmitted from the HARQ block 172 to the storage device 171 to delete the corresponding data from the storage device (S105). In addition, the transmission result for the data block that has been successfully transmitted or failed to be transmitted is reported to the scheduler 174 so that the scheduler can consider the interruption or retransmission of the data (S106).

Currently, the scheduling algorithm used in the HSDPA system is based on the priority information of each data. In other words, the scheduler observes data for various terminals in the storage in the MAC-hs sublayer and transmits the highest priority data first.

In general, the overall efficiency and transmission capacity of the system is highly dependent on the scheduling algorithm used. Therefore, in order to guarantee the quality related to the transmission rate or delay time required to provide various services, an appropriate scheduling algorithm is required for each service. have.

Priority information of each data is transmitted between the base station and the RNC through the HS-DSCH FP (Frame Protocol) carrying data for HSDPA.

FIG. 6 shows a structure of a data frame of the HS-DSCH FP used to transfer data transmitted through the HS-DSCH.

The Common Channel Priority Indicator (CmCH-PI) field of the data frame field indicates the priority of MAC-hs SDUs transmitted through the data frame, and the value of CmCH-PI is 16 values from 0-15. Have

In this case, the data with priority 0 means the lowest priority, and the data with priority 15 becomes the data with the highest priority.

For reference, in FIG. 6, the header cyclic redundancy checksum (CRC) is a field used for detecting an error of header information of a data frame, and the payload CRC is used to detect an error of a remaining data portion except for a header in the data frame. .

The FT field is identification information used to distinguish the type of the corresponding frame. The FT field is set to "1" for a data frame and "0" for a control frame carrying control information.

NumOfSDU refers to the number of MAC-hs SDUs included in the data frame, and User Buffer Size indicates the size of data having the same CmCH-PI value stored in the RNC in 8-bit units. Finally, the Spare Bit is an extension bit that is not currently used but is reserved for future use.

As such, the conventional data transmission order is determined entirely by priority information of data transmitted through the HS-DSCH FP. However, services in which priority information of data is provided in the HSDPA system are limited to only some of various multimedia services. To understand this, let's take a look at the communication services provided by UMTS, the parent system including the HSDPA system.

UMTS supports four types of services, depending on the nature of the service. These include "Conversational" services such as voice calls and video calls, "Streaming" services that provide on-demand video or on-demand music, "Interactive" services such as web browsing or file downloads, and "Background" such as e-mail. "Service.

At this time, the conversational service and the streaming service belong to a real time service that is sensitive to delay time, and the interactive service and the background service are non-real time services that are not very sensitive to the delay time.

The services provided through the HSPDA system include all three types of services except for the Conversational service. Since these services have different characteristics and requirements for transmission, a scheduling algorithm suitable for the characteristics of each service and scheduling control information for the services are required to guarantee a certain level of transmission quality for each service.

However, the current HSDPA system determines the transmission order of data using only the priority of the data, so that it cannot be expected to operate in accordance with the purpose of providing a multimedia service. This is because the purpose of the conventional public transport channel is focused on non-real-time services rather than real-time services.

In other words, current public transport channels are designed to transmit only non-real-time services such as interactive services, and therefore, priority information on the corresponding services is needed and this information is used as basic information for transmitting data in the scheduler.

In contrast, another type of service provided by the HSDPA system, a real-time service, is a transmission condition in which the transmission delay time of the data is more important than the priority information of the data. In other words, in the case of real-time data, it is no longer valuable as data after a certain delay time.

Examples of such services include voice services or video telephony, and data that has been delayed for some time is usually discarded.

Accordingly, the present invention proposes a method in which the scheduler of the HSDPA system can guarantee the transmission quality according to the characteristics of each service in a multimedia environment where a real time service and a non real time service coexist.

Therefore, in the present invention, in order to solve the above problems, in the high-speed downlink packet access (HSDPA) system for providing a multimedia service, the scheduler located in the base station to ensure the transmission quality according to the characteristics and requirements of each service data Provides a scheduler and a data transmission control method for a high-speed downlink packet access system that receives the control information related to the transmission from the upper layer to efficiently distribute the radio resources in consideration of the information related to the delay time of the data There is a purpose.

1 is a structure of a UMTS radio access network (UTRAN) of 3GPP.

2 is a protocol structure of a radio access interface.

3 is a radio access protocol structure for a high speed downlink packet access system.

4 is a structure of a MAC layer for supporting a high speed downlink packet access system.

5 is a scheduler structure in the conventional MAC-hs sublayer.

6 is a structure of a data frame used in the conventional HS-DSCH FP.

7 is a structure of a packet scheduler for an HSPDA system according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

161 ... MAC-d sublayer 162 ... MAC-c / sh sublayer

163 MAC-hs sublayer 171,201 Storage device

172,203 ... HARQ blocks 173,205 ... Physical layer

174,207 scheduler 209 control information management device

Packet data transmission method of the high-speed downlink packet access system according to the present invention for achieving the above object, the quality state information of the physical channel, data to be transmitted, scheduling control information, etc. for data transmission from the base station to the downlink Receiving a; Determining a transmission order by reflecting channel quality status information and scheduling control information in the scheduler; And transmitting the data transmitted from the upper layer through the physical layer in the transmission order.

Preferably, in the present invention, the medium access control layer is characterized by receiving data and control information about transmission of the data from an upper layer.

Preferably, in the present invention, the control information regarding the packet data transmission includes a transmission delay time in which data transmitted to the medium access control layer stays in an upper layer.

Preferably, in the present invention, the transmission delay time is transmitted through a transmission protocol of the Iur interface or the Iub interface with the associated data.

Preferably, the data frame used in the transmission protocol of the present invention comprises data to be transmitted and a transmission delay time in an upper layer of the data in order to distinguish it from a conventional data frame for transmitting priority information of data. do.

Preferably, the data frame used in the transmission protocol of the present invention is characterized by adding a field for distinguishing the header information of the data frame to distinguish it from the conventional data frame for transmitting the priority information of the data. .

Preferably, the data frame used in the transmission protocol of the present invention is characterized by including the data to be transmitted, priority information of the data, transmission delay time information in the upper layer of the data.

Preferably, the data frame of the present invention is characterized by setting and using necessary fields according to the characteristics of the service.

Preferably, in order to indicate a field to be used in the data frame, a field indicating this is added to header information of the data frame.

Preferably, the transmission delay time is discretized in units of a transmission time interval (TTI) used as a basic unit of transmission in a high speed downlink packet access system.

Preferably, the transmission delay time includes a time in which the corresponding data is not transmitted in the medium access control layer.

Preferably, the scheduler compares the delay time information of the data with the maximum transmission delay time for the service, and assigns a weight of priority transmission to data having a small difference between the delay time and the maximum transmission delay time.

Preferably, the scheduler is characterized in that, if the delay time of the data exceeds the maximum transmission delay time for the service, stop the transmission by discarding the data, and informs the upper layer.

Preferably, the maximum transmission delay time is received from the control layer in the upper layer while establishing a connection between the terminal and the core network for the service.

Preferably, the upper layer is NBAP (Node B Application Protocol) on the Iur interface.

Preferably, the packet data transmission control information is priority information of the corresponding data, and the priority information is dynamically set based on the transmission delay time of the corresponding data in the upper layer and is transmitted to the media access control layer. do.

Preferably, the priority information of the data compares the transmission delay time with the maximum transmission delay time and assigns a higher priority weight as the transmission delay time is closer to the maximum transmission delay time value.

The objects and features according to the present invention will become apparent from the following detailed description of the embodiments with reference to the accompanying drawings.

The HSDPA system must be able to support both real-time and non-real-time services at the same time. In the case of the non-real-time service, the transmission priority may be determined based on the relative priority of the data as in the conventional method, but in the case of the real-time service, it is necessary to determine the transmission priority in consideration of the data delay time.

Consider an operation of a scheduler supporting a real-time service in a high speed downlink packet access system according to the present invention.

The delay time of the real time data means the delay time of the corresponding data between end-to-end terminals connected to the service. This delay can occur in various parts of the packet's transmission path, including the wireless interface, UTRAN, and the core network.

To this end, in the UMTS network supporting the HSDPA system, the maximum delay time is defined to ensure the transmission delay time of the corresponding service at least in the network area managed by the HSDPA system. In other words, the UMTS network cannot guarantee the transmission delay time for other networks that it does not manage, but it guarantees the transmission delay time that was agreed upon when the connection of the service was established for the packet entering the UMTS network. I should be able to give In general, the transmission delay time of real-time data should be set not to exceed 250ms from the SGSN or MSC, which is the core network of UMTS network, to the terminal located at the end. Therefore, although it depends on the kind of real-time service, the maximum delay time is set in the range which does not exceed this value.

Data entered into the UMTS network from the outside is transmitted to the RNC of the UTRAN via SGSN or MSC of the core network, and finally transmitted from the base station to the terminal. Based on the UTRAN, since the location of the buffer to store the data is the RLC layer of the RNC, most of the delay may be caused by the RNC.However, in the HSDPA system, the data may be located in the base station in addition to the RNC. The delays in these two parts must be considered at the same time.

In addition, since the base station is responsible for the transmission of the real-time service, the scheduling of the base station needs to know the transmission delay time in the RNC in order to enable scheduling in consideration of the transmission delay time of the real-time data.

In this case, the transmitted delay information may be an actual delay time and, in some cases, may mean an urgency of the corresponding data, and thus information instead of the actual delay time may be set. Detailed description thereof will be described later. Information transmitted from the upper layer to the MAC-hs sublayer in relation to the delay information of the data will be referred to as "scheduling control information".

The present invention proposes a method in which an RNC informs a base station of scheduling control information of real time data through an Iur interface or an Iub interface. That is, when providing a real-time service in the HSDPA system, using the transmission protocol HS-DSCH FP proposes a method for transmitting the scheduling control information related to the delay time of the data with the data of the real-time service.

7 is a scheduler structure of the MAC-hs sublayer according to the present invention.

Referring to FIG. 7, the MAC-hs sublayer located in the base station receives real time data and scheduling control information related to delay information of the corresponding data.

The control information management apparatus manages the transferred control information and transfers the control information to the scheduler as necessary.

MAC-hs SDUs and their scheduling control information are stored in the storage device 201 and the control information management device 209, respectively. When the scheduler 207 receives the buffer state information from the storage device 201, the scheduler 207 receives the scheduling control information related to the delay time of each data (S212).

If the existing non-real time data is transmitted or the transmission delay time information is converted into priority information, the priority information may be received. That is, in the multimedia service in which the real-time service and the non-real-time service coexist, the buffer status information S212 includes the amount of data in the buffer, delay time or priority information of the data, and the scheduler 207 includes the physical layer 205. Channel state information is received from (S213).

When the scheduler 207 receives the buffer status information and the channel status information, the scheduler 207 performs scheduling for data transmission control based on the buffer status information and the channel status information to determine the size of the data block to be transmitted and the MAC-hs SDUs to be transmitted. . The determined data block is transmitted to the HARQ block 203 by adding the priority identifier and the TSN and transmitted through the physical layer 205 (S214 and S215).

At this time, when the storage device 201 receives a transmission result indicating that a specific data block is successfully transmitted from the HARQ block 203 (S216), the storage device 201 deletes the corresponding data in the device and is associated with the data. The scheduling control information 209 is also deleted.

If the transmission fails, the HARQ block 203 notifies the scheduler 207 of the transmission result so that the corresponding data can be retransmitted during the scheduler operation (S217).

Looking at the scheduling control information related to the delay time transmitted from the upper layer to the MAC-hs sublayer in detail, two kinds of scheduling control information can be considered.

First, the actual delay time of the packet in the upper layer may be mentioned.

That is, the time spent in the upper layer is transferred to the MAC-hs sublayer through the HS-DSCH FP. Therefore, an additional field for including delay information according to the data frame of the HS-DSCH FP is required.

In this case, the value entering the corresponding field may include actual delay time information. However, since the value of the field should be expressed as a digital value, it is necessary to insert the delay time in an appropriate unit.

For example, if the delay time is 95.32ms, it is not possible to send this information correctly. Therefore, it is appropriate to send in an appropriate reference unit such as 1ms or 2ms. For example, if the reference unit is 1ms, a value of 95 may be set.

However, the method provided by the present invention is to set the reference unit to TTI, which is a basic time unit used for data transmission in HSDPA.

That is, since each data block is transmitted in units of TTIs, the scheduler's interest is actually a transmission location in units of TTIs rather than an accurate delay time.

In general, the maximum delay time provided by UMTS is about 250ms, so the time spent in the upper layer will not exceed this value.

Therefore, if the TTI is 2ms, since the required field size is 125, only 7 bits may be sufficient to inform the delay information.

In addition, although the conventional HS-DSCH FP data frame was able to transmit data and priority information of the data so as to be suitable for non-real-time data, the new HS-DSCH FP has no priority information in real time service. Data and related control information to the MAC-hs sublayer.

In this case, data frames used for the real time service and the non-real time service should be set differently.

Therefore, the present invention proposes to use independent HS-DSCH FP data frames for real-time and non-real-time services. In this regard, in order to distinguish two types of data frames, a field for identifying the data frame header information is required.

That is, the base station can know the type of data included in the data frame through this additional header field.

By using no additional data frame, a more general data frame different from the current data frame can be used so that the same HS-DSCH data frame can be used for real time data and non-real time data.

That is, in addition to the conventional HS-DSCH FP data frame by adding a field for indicating the delay time information of the data, when transmitting the real-time data, using the field associated with the delay time information, and transmits non-real-time data In this case, it is a method of using a field related to a conventional priority.

That is, a field to be used is determined according to the type of service, and a field not to be used is not set. This method will also require a field to distinguish the type of service and the field used in the data frame of the HS-DSCH FP.

Secondly, priority information is used as scheduling control information. In other words, the same priority information as that of the non-real time data may be used as the scheduling control information of the real time data to reduce the influence on the current HSDPA system.

However, if there is fixed priority information as in the conventional method, since the quality of the real-time service cannot be guaranteed, a method of setting the variable priority information according to the data delay time is used to compensate for this. .

That is, since the delay time is an important factor in the real time data, the RNC may use a method of dynamically allocating priority information of the corresponding data in consideration of the delay time of the data.

Therefore, if the delay time of a specific data is increased and a rapid transmission is necessary, a large priority is given to the corresponding data, and if not, a proper priority is assigned to the data. Real-time data will have a relatively high priority because it has a relatively urgent transmission characteristic compared to non-real-time data.

If the same HS-DSCH FP data frame is used as in the second method, there is an advantage that the current system can be used as it is, but it is unknown whether the transmission quality of the real-time service can be guaranteed.

For example, even if the maximum transmission delay time is 200ms and the current delay time is 150ms, even if the transmission is very urgent, the scheduler located in the base station simply uses the priority information and thus transmits data having a higher priority. If time is consumed, the delay time will continue to increase, resulting in a loss of transmission quality for the real-time service.

Next, considering the scheduling method of the scheduler 207 according to the present invention, it is possible to vary the transmission method according to the type of scheduling control information. First, consider the case of informing the delay time of the real-time data by the control information. In this case, the scheduler knows the delay information of the corresponding data transmitted from the upper layer, and also knows the delay time added after the transmission to the MAC layer, so that the total delay time of the data can be known. In this case, the total delay time of the data means a time taken until the corresponding data is successfully transmitted from the base station to the terminal. Therefore, the total delay time of the specific data is the sum of the delay time in the upper layer and the time in the MAC layer. Therefore, by using the method of transmitting data starting from the data which is close to the maximum transmission delay time due to the total delay time of the corresponding data, data discarded over time can be reduced. Next, if the dynamic priority allocation method is used as the scheduling control information, the highest priority data is transmitted first based on the received priority information as in the conventional scheduling method.

In addition, when the actual delay time is used as the scheduling control information, it is necessary to inform the base station of the maximum delay time information when the service is set up so that the scheduler located in the base station can schedule using the maximum delay time information set for the corresponding service. .

The base station compares the delay information of the data transmitted from the RNC with the delay time information retained by the base station and compares it with the maximum delay time, and preferentially transmits data having a small difference between the maximum delay time value and the total delay time value.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments.

Therefore, the above description is not limited to the scope of the invention defined by the limitations of the claims.

As described above, according to the operation method of the packet scheduler for the high speed downlink packet access (HSDPA) system according to the present invention, when the scheduler for allocating radio resources in the base station of the high speed downlink packet access (HSDPA) system By considering the information related to the delay time of the data, scheduling is possible considering the delay time of the data as well as the priority of the data according to the characteristics of the service in the multimedia service. Scheduling is possible, which has the effect of ensuring the quality of multimedia services.

Claims (17)

Transmission of packet data to be transmitted for downlink data transmission, quality state of physical channel, and control information regarding transmission of the packet data in a base station media access control layer of a mobile communication system supporting downlink packet transmission Receiving step; Determining a transmission order of packet data based on the control information about the packet data transmission; And transmitting the packet data to be transmitted through the physical layer according to the transmission order. The method of claim 1, wherein the medium access control layer receives data and control information about transmission of the data from an upper layer. 3. The method of claim 2, wherein the control information about the packet data transmission includes a transmission delay time in which data transmitted to the medium access control layer stays in an upper layer. 4. The method of claim 3, wherein the transmission delay time is transmitted through a transmission protocol of an Iur interface or an Iub interface together with associated data. 5. The data frame of claim 4, wherein the data frame used in the transmission protocol is composed of data to be transmitted and a transmission delay time in an upper layer of the data in order to distinguish it from a conventional data frame in which priority information of data is transmitted. Packet data transmission method. 5. The method of claim 4, wherein the data frame used in the transmission protocol adds a field for distinguishing the data frame to header information of the data frame to distinguish the data frame from the conventional data frame for transmitting the priority information of the data. Packet data transmission method. 5. The method of claim 4, wherein the data frame used in the transmission protocol comprises data to be transmitted, priority information of the data, and transmission delay time information in an upper layer of the data. 8. The method of claim 7, wherein the data frame sets and uses necessary fields according to characteristics of a service. 9. The method of claim 8, wherein a field indicating the field is added to header information of the data frame to indicate a field to be used in the data frame. 4. The method of claim 3, wherein the transmission delay time is discretized in units of a transmission time interval (TTI) used as a basic unit of transmission in a fast downlink packet access system. The packet scheduler as claimed in claim 3, wherein the scheduler of the base station medium access control layer adds the transmission delay time and the time that the corresponding data is not transmitted in the medium access control layer and uses the total delay time for the corresponding data. Data transfer method. 12. The method of claim 11, wherein the scheduler compares the total delay time information of the data with the maximum transmission delay time for the service, and assigns a weight of priority transmission to data having a small difference between the total delay time and the maximum transmission delay time. A packet data transmission method characterized by the above-mentioned. The method of claim 12, wherein the scheduler stops the transmission by informing the upper layer if the total delay time of the data exceeds the maximum transmission delay time for the service, and notifies the upper layer. The method of claim 12, wherein the maximum transmission delay time is received from a control layer in a higher layer while establishing a connection between a terminal and a core network for a corresponding service. 15. The method of claim 14, wherein the upper layer is a Node B Application Protocol (NBAP) on an Iur interface. 3. The method of claim 2, wherein the packet data transmission control information is priority information of the corresponding data, and the priority information is dynamically set based on the transmission delay time of the data in the upper layer and transferred to the media access control layer. Packet data transmission method characterized in that. 17. The packet data of claim 16, wherein the priority information of the data compares the transmission delay time with the maximum transmission delay time and assigns a higher priority weight as the transmission delay time is closer to the maximum transmission delay time value. Transmission method.