KR20070063349A - Method for scheduling of node-b in high speed downlink packet access communication system - Google Patents

Abstract

A scheduling method for node-Bs in an HSDPA(High Speed Downlink Packet Access) system is provided to carry out scheduling so that an HS-PDSCH(High Speed-Physical Downlink Shared Channel) can be allocated suitably according to the data rate of a UE(User Equipment) if a real-time operation is required after confirming the application QoS(Quality of Service) of the UE. A UE(20) transmits the QoS of an application to a node-B(16) through an HS-DPCCH(High Speed-Dedicated Physical Control Channel)(302). Receiving the application QoS from the UE, the node-B judges whether a real-time operation is required(304). If it is judged that the real-time operation is required as the UE is executing an application which requires real-time data transmission, the node-B executes scheduling so that the UE can seamlessly and continuously executes the application(306).

Description

METHODOLOGY FOR SCHEDULING OF NODE-B IN HIGH SPEED DOWNLINK PACKET ACCESS COMMUNICATION SYSTEM}

1 is an exemplary channel use of the network and the terminal in a typical HSDPA system

2 is a block diagram of an HSDPA system according to an exemplary embodiment of the present invention.

3 is a flowchart illustrating a scheduling method of a base station according to an exemplary embodiment of the present invention.

4 is a detailed flowchart illustrating a scheduling process of a base station according to an exemplary embodiment of the present invention.

The present invention relates to a high speed mobile communication system, and more particularly, to a scheduling method of a base station in a high speed downlink packet access (HSDPA) system.

HSDPA system is an asynchronous 3.5 generation mobile communication service, which is the evolution of 3rd generation W-CDMA, which can theoretically receive up to 14Mb per second, and is a high speed mobile communication system that can receive data at a speed of 2 ~ 3Mbps. . Accordingly, the HSDPA system has recently been commercialized to speed up the mobile data communication environment.

In such an HSDPA system, a network allocates a plurality of codes to one terminal, determines a channel coding rate and a modulation scheme according to a wireless channel situation, and uses an Automatic Repeat Request (ARQ) between the base station and the terminal, not between the base station controller and the terminal. Automatic retransmission request) to maximize forward transmission capability.

1 is a view showing a channel used between the network and the terminal in a typical HSDPA system.

Referring to FIG. 1, a high speed-physical downlink shared channel (HS-PDSCH) channel in step 102 is a channel for transmitting substantial user data to a user equipment (UE) 200 by a network 100. The HS-PDSCH channel is a forward channel and may be composed of a plurality of codes and is shared by a plurality of terminals. The coding rate and modulation scheme of the HS-PDSCH channel are adaptively determined according to channel conditions, and an ARQ operation is performed on data transmitted through the HS-PDSCH channel between the base station and the terminal.

In addition, the High Speed-Shared Control Channel (HS-SCCH) channel of step 104 is a channel for the network 100 to transmit information necessary for decoding the HS-PDSCH channel to the UE 200. The HS-SCCH channel is a forward channel. The HS-SCCH channel transmits a code number and code position of the HS-PDSCH channel, an amount of data to be transmitted per unit time, a modulation scheme, and ARQ related information.

In addition, in step 106, the downlink-dedicated physical channel (DL-DPCH) and uplink-dedicated physical channel (UL-DPCH) in step 108, the network 100 performs HSDPA communication with each UE 200. The DL-DPCH channel is a forward dedicated channel, and the transmission output of the DL-DPCH channel and the transmission output of the HS-SCCH channel may be linked. The UL-DPCH channel is a reverse dedicated channel, and the transmission output of the UP-DPCH channel and the transmission output of the HS-DPCCH channel may be linked.

In addition, the high speed-dedicated physical control channel (HS-DPCCH) channel of step 120 is a reverse channel for the UE 200 to transmit control information related to HSDPA to the network 100. The UE 200 transmits channel quality information (CQI), which means radio channel quality, and ACK / NACK information indicating whether the HS-PDSCH has been received without error through the HS-DPCCH channel.

Meanwhile, the HSDPA system should allocate an HS-DSCH channel and determine a Modulation and Coding Scheme (MCS) in order for the UE 200 to receive data, and the Node-B in the network 100 is as described above. The information obtained through the same channels is used to allocate the HS-DSCH channel and determine the MCS suitable for the wireless channel environment.

First, Node-B allocates the HS-DSCH channel of the UE 200 by using a scheduling algorithm. In this case, the Node-B may allocate the HS-DSCH channel of the UE 200 using round robin scheduling or Max C / I (Carrier to Interference) scheduling algorithm. Node-B determines a radio channel environment using the CQI received from the UE 200 through the HS-DPCCH channel during scheduling, and determines an MCS suitable for the radio channel environment.

As described above, as the HS-DSCH channel is allocated and the MCS for the wireless channel environment is determined, the data rate that the UE 200 can receive from the network 100 is determined, and the Node-B determines Scheduling is performed according to the data rate.

However, the scheduling of Node-B as described above is performed in consideration of only the radio channel environment, and is performed regardless of the application being performed by the UE 200. There is a problem that the case is not smooth in running the actual application.

Accordingly, an aspect of the present invention is to provide a scheduling method of a base station in a high-speed mobile communication system that performs scheduling in consideration of the application QoS of the UE as well as the wireless channel environment.

In another aspect, the present invention is to provide a scheduling method of a base station in a high-speed mobile communication system that performs scheduling so that the HS-PDSCH channel is allocated according to the processing data rate of the UE when a real-time operation is required as a result of application QoS determination of the UE.

In order to achieve the above object, the present invention provides a scheduling method of a base station in a high-speed mobile communication system, the process of receiving an application quality of service (QoS) from the terminal, and whether or not the need for real-time data transmission through the application QoS And determining, if the real-time data transmission is necessary, scheduling the transmission data rate of the base station and the processing data rate of the application according to a comparison result.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the same components in the drawings are represented by the same reference numerals and symbols as much as possible even if shown in different drawings. In addition, in the following description of the present invention, if it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 is a block diagram of a high speed downlink packet access (HSDPA) system according to an embodiment of the present invention. 2, an HSDPA system according to an embodiment of the present invention includes a core network (CN) 12, a radio nework controller (RNC) 14, a node-B 16, and a user equipment (UE) 20. It includes.

The CN 12 is a core network of the HSDPA system, performs call processing of subscribers, controls mobility, and performs switching in a network. The CN 12 may be composed of a circuit switched area, a packet switched area, and a register area. The CN 12 may manage a circuit switched connection through the circuit switched area, manage mobility, and provide a passage to the external network through the circuit switched area. do. In addition, the packet switching area is responsible for the management and resources of the packet switching service, and performs connection to other packet switching networks. In addition, the register area stores and manages subscriber information and security-related information and performs authentication functions for subscribers and services.

The RNC 14 is a base station controller, which controls radio resources in the HSDPA system and is connected to a packet switched area or a circuit switched area of a core network to support various multimedia traffics. According to an embodiment of the present invention, the RNC 14 receives the QoS of the application in the form of RRC MSG from the UE 20 and provides the QoS to the corresponding Node-B 16.

The Node-B 16 serves as a base station for communication with the UEs 20 and receives a radio signal from the UE 20 or transmits a radio signal to the UE 20 in a radio communication section. The Node-B 16 establishes a radio access physical channel for the UE 20 and maximizes forward transmission capability by determining a channel coding rate and a modulation scheme according to a radio channel situation. In addition, the Node-B 16 receives the application QoS of the UE 20 and performs scheduling by reflecting the application QoS of the UE 20 according to an embodiment of the present invention.

As the user terminal, the UE 20 supports various forms such as voice data and multimedia data and performs various applications. In addition, the UE 20 transmits a Quality of Servic (QoS) including a data rate required to perform the application to the Node-B 16 when the application is executed.

That is, in the HSDPA system according to the embodiment of the present invention as described above, the Node-B 16 receives the application QoS from the UE 20 and performs scheduling accordingly. 3 is a flowchart illustrating a scheduling method of a Node-B 16 in an HSDPA system according to an exemplary embodiment of the present invention. Referring to FIG. 3, the UE 20 transmits an application QoS to the Node-B 16 in step 302.

In this case, the UE 20 may transmit the QoS of the application including the data rate required to perform the application to the Node-B 16 through the HS-DPCCH channel as illustrated in step 110 of FIG. 1. The UE 20 may also send the QoS of the application to the RNC 14 in the form of an RRC MSG, and allow the RNC 14 to transmit the QoS of the application to the Node-B 16.

The Node-B 16 receives the application QoS from the UE 20 and determines the need for real-time operation in step 304. For example, the Node-B 16 determines whether the UE 20 is executing an application requiring real time data transmission.

In operation 306, the Node-B 16 performs scheduling according to a result of determining whether a real-time operation is required. For example, when the UE 20 is executing an application requiring real-time data transmission, the Node-B 16 performs scheduling so that the application is continuously performed without being interrupted. In addition, the Node-B 16 performs scheduling according to a conventional scheduling algorithm when the UE 20 is executing an application that does not require real-time data transmission.

Referring to the scheduling process of the Node-B 16 as described above in more detail, FIG. 4 is a detailed flowchart of the scheduling process of the Node-B 16 according to an embodiment of the present invention. Referring to FIG. 4, the Node-B 16 receives an application QoS from the UE 10 in step 402. The Node-B 16 may receive the application QoS from the UE 10 via the HS-DPCCH channel, and may receive the QoS of the application from the RNC 14.

When the application QoS of the UE 10 is received, the Node-B 16 grasps the class through the application QoS in step 404. At this time, the Node-B 16 determines whether the application QoS is one of four classes such as a conversational class, a streaming class, an interactive class, and a background class.

In operation 406, the Node-B 16 determines whether real-time data transmission is necessary through the class. If real-time data transmission is required, the application of the UE 10 should operate continuously. If real-time data transmission is not necessary, the application of the UE 10 does not need to operate continuously. to be. Of the four classes, the conversational class and the streaming class are classes that require real-time operation.

As a result of determining whether the real-time data transmission is necessary, the Node-B 16 uses the CQI (Channel Quality Information) received from the UE 10 through the HS-DPCCH channel in step 408 when real-time data transmission is required. Calculate the transmission data rate.

In this case, CQI is a value of radio channel quality, and has a value between 0 and 31. Among these, values between 1 and 30 indicate a specific channel situation, and 0 and 31 are not used. For example, CQI 1 refers to a channel situation in which 137 bits can be modulated with Quadrature Phase Shift Keying (QPSK) and then transmitted with one Switching Fabric (SF) 16 code. CQI 30 refers to a channel situation in which 7168 bits can be modulated by 16-QAM (Quadrature Amplitude Modulation) and then transmitted using five SF 16 codes. That is, as the CQI value increases, the channel situation is better. The Node-B 16 determines the radio channel environment with the CQI reported from the UE 10, and accordingly determines a Modulation and Coding Scheme (MCS), and calculates a maximum transmission data rate according to the determined MCS.

As a result of calculating the maximum transmission data rate, the Node-B 16 calculates data throughput for one period of TTI (Transfer Time Interval) using the maximum transmission data rate in step 410. For example, assuming that the maximum transmission data rate of the Node-B 16 is 6Kbyte / ms and one TTI section is 2ms, the data rate in the TTI section may be 12Kbyte / 2ms.

After calculating the data rate in one TTI section as described above, the Node-B 16 checks the data rate required by the application of the UE 10 in step 412.

In step 414, the Node-B 16 compares the amount of transmission data with the amount of application processing data during the TTI period.

For example, assuming that the data rate in one section of the TTI is 12Kbyte / 2ms, and that the data rate required by the application of the UE 10 is 7Kbyte / ms, the Node-B 16 generates a 12Kbyte data amount for 2ms. The application will process 14Kbytes for 2ms. In other words, the amount of transmitted data becomes smaller than the amount of application processing data during one TTI period. When the amount of transmitted data is smaller than the amount of application processing data during one TTI period, the Node-B 16 may not satisfy the amount of data required by the application of the UE 10 per unit time.

If the Node-B 16 cannot meet the amount of data required by the application of the UE 10 per unit time, the UE 10 immediately processes the data transmitted from the Node-B 16 during the TTI 1 interval. In other words, it must wait until the next TTI interval data is transmitted from the Node-B 16. However, since the Node-B 16 schedules each of the plurality of UEs once and then allocates a channel to the UE 10 again, the UE 10 takes a long time to receive data of the next TTI interval.

For example, the amount of data required by the application is 150 bits / ms, the amount of data transmitted in the Node-B 16 determined by the CQI is 100 bits / ms, and the scheduling is a TTI (2 ms) based round robin method. Assume that there are 100 terminals. Then, the UE 10 receives 200 bits of data per TTI from the Node-B 16, while the data processing time is 1.33 ms (200 bits / 150 bits / ms), and the next scheduling time is 200 ms (100 * TTI). After 1.33ms of data processing time, 198.67ms (200ms-1.33ms) should wait. This is the case where data processing in one TTI section is possible. (TTI: 2ms, Terminal data processing time: 1.33ms)

When waiting until the data of the next TTI interval is received as described above, the application of the UE 10 cannot perform an operation for a time when the data is not received.

Accordingly, as a result of comparing the transmission data amount and the application processing data amount during the TTI section, if the amount of transmission data is smaller than the application processing data amount during the TTI section, the Node-B 16 proceeds to step 416 to continuously allocate the HS-PDSCH channel. Perform scheduling. As such, when scheduling is performed such that the HS-PDSCH channel is continuously allocated, the UE 10 does not have to wait until receiving data of the next TTI interval.

On the other hand, assuming that the data rate in one section of the TTI is 12Kbyte / 2ms and that the data rate required by the application of the UE 10 is 5Kbyte / ms, the Node-B 16 provides a data amount of 12Kbyte for 2ms. The application will process 10Kbytes for 2ms. In other words, the amount of transmitted data becomes larger than the amount of application processing data for one period of TTI. As such, when the data amount is greater than the application processing data amount during one TTI period, the Node-B 16 may satisfy the data amount required by the application of the UE 10 per unit time.

If the Node-B 16 can satisfy the amount of data required by the application of the UE 10 per unit time, the Node-B 16 is more than the amount of data that the application of the UE 10 can process per unit time. If you send more data.

For example, the amount of data required by the application is 5 bits / ms, the amount of transmission data in the Node-B 16 determined by the CQI is 600 bits / ms, and the scheduling is a TTI (2 ms) based round robin method. Assume that there are 100 terminals. Then, the UE 10 receives 1200 bits of data per 1 TTI (2ms) from the Node-B 16, whereas the data processing time received during one TTI interval is 240ms (1200bit / 5bit / ms), which is a TTI 120 interval. It corresponds to.

In this case, the application of the UE 10 cannot process all the data transmitted from the Node-B 16 during the TTI period, and the time required for processing all the data transmitted from the Node-B 16 is longer. I get caught. Accordingly, the UE 10 does not need to be allocated a channel from the Node-B 16 until all of the transmitted data is processed even after the TTI 1 interval.

Accordingly, the Node-B 16 proceeds to step 418 when the amount of transmitted data is greater than the amount of application processing data during one TTI period, and the data processing time until the application of the UE 10 processes all data received during the one TTI period. Is calculated and the calculated data processing time is converted into a value in TTI units. For example, if the time required is 238 ms more than the TTI time (2 ms here), the more necessary 238 ms may be converted to the TTI 119 interval.

The Node-B 16 allocates an HS-PDSCH channel to the UE 10 by offsetting the TTI value in step 420. For example, the TTI 119 has a time offset, and the channel is assigned an HS-PDSCH channel so that another UE can utilize the channel during the TTI 119 interval.

After allocating the HS-PDSCH channel as described above, the Node-B 16 determines whether the application of the UE 10 is terminated in step 420. If the application of the UE 10 is not terminated, the Node-B 16 proceeds to step 408 and repeats steps 408 to 420 until the application is terminated.

On the other hand, if the real-time operation is not necessary in step 406, the Node-B 16 allocates the HS-PDSCH channel to the UE 10 by performing normal scheduling in step 422.

In the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the equivalent of claims and claims.

As described above, the present invention has an effect of smoothing the application operation of the terminal having various QoS by performing scheduling in consideration of the application QoS of the terminal as well as the wireless channel environment in the ultra-high speed mobile communication system.

In addition, the present invention has an effect that if the transmission data rate of the base station is smaller than the application processing data rate, by continuously assigning channels, the application of the terminal does not have to wait until the next data is transmitted after data processing is completed.

In addition, when the transmission data rate of the base station is larger than the application processing data rate, it is possible to increase the channel allocation efficiency by allowing a channel to be allocated to another terminal until the application processes the transmission data.

Claims (8)

A scheduling method of a base station in a high speed mobile communication system, Receiving an application quality of service (QoS) from the terminal; Determining whether real-time data transmission is necessary through the application QoS; And scheduling according to a result of comparing a transmission data rate of the base station and a processing data rate of the application when the real-time data transmission is required. The method of claim 1, wherein the determining of whether the real-time data transmission is necessary is performed. Identifying a class of the application QoS; And determining whether the identified class is a class requiring real-time data transmission. The method of claim 2, The class includes at least a conversational class, a streaming class, an interactive class, a background class, the scheduling method of the base station in the high-speed mobile communication system, characterized in that. The method of claim 1, wherein the performing of the scheduling comprises: Calculating a transmission data rate using a radio channel quality (CQI) from the terminal if the real-time data transmission is necessary; Checking a data rate required by the application of the terminal; Comparing the transmission data rate of the base station with the application processing data rate for one period of transfer time interval (TTI), As a result of the comparison, if the transmission data rate of the base station is small, continuously allocating a channel for data transmission to the terminal; If the transmission data rate of the base station is large, the scheduling method of the base station in the high-speed mobile communication system comprising the step of assigning the next channel with a time offset by the time required for the application to complete the data processing. The method of claim 1, If the real-time data transmission is not necessary, the method for scheduling a base station in a high-speed mobile communication system, characterized in that it further comprises the step of assigning a channel to the terminal according to a wireless channel environment. The method of claim 4, wherein The channel for data transmission is a scheduling method of a base station in a high-speed mobile communication system, characterized in that the HS-PDSCH (High Speed-Physical Downlink Shared Channel) channel. The method of claim 4, wherein If the transmission data rate of the base station is large, the scheduling method of the base station in the high-speed mobile communication system, characterized in that for assigning a channel to another terminal for a time offset for the time required for the application to complete the data processing. The method according to any one of claims 1 to 6, The high speed mobile communication system is a scheduling method of a base station in a high speed mobile communication system, characterized in that the HSDPA system.

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