KR101010379B1 - Apparatus and method of scheduling - Google Patents

Abstract

The present invention relates to scheduling of a portable Internet system, and more particularly, to a scheduling method and apparatus for improving data transmission efficiency.

According to an embodiment of the present invention, a scheduling method includes: scheduling data of a real-time service in a current frame; After scheduling the data of the real-time service, the scheduling of the data of the non-real-time service is performed, and weighting is given when scheduling the data of the non-real-time service to a terminal on which the data of the real-time service is scheduled among a plurality of terminals. It features.

Frame, Scheduling, Proportional Fair, MAP_IE, Class of Service

Description

Scheduling method and apparatus {Apparatus and method of scheduling}

The present invention relates to scheduling of a portable Internet system, and more particularly, to a scheduling method and apparatus for improving data transmission efficiency.

In the portable Internet system, a data transmission order to be transmitted is determined by applying a scheduling method suitable for each service characteristic according to the type of service to be provided. Subsequently, a radio channel of data waiting to be transmitted is allocated and a size of a data that can be transmitted is determined, and a frame is formed based on this, and the frame is transmitted using a physical layer. In this case, scheduling according to a service is generally performed first for a real-time service such as an unsolicited grant service (UGS), a real-time polling service (rtPS), or an extended real-time polling service (ertPS). Scheduling is performed sequentially for non real-time services such as nonreal-time polling service (BE) and best effort service (BE).

There are many factors that affect the data transmission efficiency, and the representative one is scheduling. Scheduling is an algorithm that determines the order of transmission in order to share a given radio resource among multiple users, which is an important factor in determining the quality of service (QoS) and system performance.

In order for a plurality of user terminals to be stably provided using a limited radio resource, scheduling must be performed so that the plurality of user terminals can efficiently occupy the radio channel. In particular, in the case of a portable Internet system, the data transmission rate may vary depending on the channel state according to the location of the user terminal, and thus, it is difficult to guarantee the fairness of services among a plurality of user terminals.

For this reason, scheduling must be able to flexibly control efficiency and fairness while simultaneously considering system efficiency and fairness between users. A representative method in consideration of this is a proportional fair scheduling method (hereinafter referred to as PF scheduling method).

The conventional PF scheduling method does not take into consideration such matters as minimum data rate, delay, and jitter, and thus is suitable for non real-time services such as nrtPS and BE. Similarly, the ratio of the currently available transmission rate for all users to the terminal and the average transmission rate of the data to which the burst has been transmitted so far is calculated, and a radio resource is preferentially allocated to a user having a high ratio. That is, the radio resources are preferentially allocated to users with higher current transmission expectations, such as data rates that can be transmitted, compared to average performance values such as average transmission rates to date, that is, users with a relatively good channel state (CINR). To improve system performance.

는 현재까지 전송한 데이터 버스트의 평균량 즉, 평균 전송률을 의미하며, r_i는 현재 프레임에 전송 가능할 것으로 예상되는 기대 전송률 이다. 여기서, r_i는 CINR(Carrier to Interference and Noise Ratio)을 따라 결정되는 값으로, CINR을 의미할 수 있다. 이러한, 종래 기술의 PF 스케줄링 방법은 상기 수학식 1에 따라, 스케줄링 우선 순위 값(P_i)이 상대적으로 큰 사용자에 우선적으로 무선 자원을 할당하게 된다. 상기 수학식 1을 참조하면, 평균 전송률(

) 및 기대 전송률(r_i)에 따라 스케줄링 우선 순위 값(P_i)가 달라지며 또한, α와 β의 조절에 의해 스케줄링 우선 순위 값(P_i)이 달라짐을 알 수 있다.In Equation 1, P _i means a data burst allocation priority value of a user terminal or a connection,

Is the average amount of data bursts transmitted to date, that is, the average data rate, and r _i is the expected data rate expected to be transmitted in the current frame. Here, r _i is a value determined according to a carrier to interference and noise ratio (CINR) and may mean CINR. This, PF scheduling method in the prior art is preferentially assigns a radio resource to the user, the scheduling priority value (P _i) is relatively large in accordance with Equation (1). Referring to Equation 1, the average transmission rate (

) And an expected transmission rate (becomes a scheduling priority value (P _i) depending on r _i) In addition, it can be seen that the scheduling priority value (P _i) varies by the control of the α and β.

For example, when α = 1 and β = 0, scheduling is performed such that radio resources allocated to all users are the same as in a round robin scheme. In this case, there is an advantage in that radio resources are allocated to a user who does not have a good channel state, but a relatively low radio resource is allocated to a user who has a good channel state.

On the other hand, when α = 0 and β = 1, scheduling is performed to preferentially select a user having a high CINR and allocate resources. In this case, resources may be concentrated in a user with a good channel condition, which may be good in terms of transmission efficiency. However, since radio resources are not allocated to a user who has a poor channel condition, starvation may be caused by a user with a poor channel condition. There are disadvantages that can occur.

The PF scheduling method of the prior art is a scheduling method considering a transmittable data rate in a current frame and an average transmitted data rate so far for a specific service class, and performs service characteristics and scheduling of a mobile Internet system supporting various service classes. Due to insufficient consideration of OFDMA transmission characteristics, difficulties in efficient radio resource utilization may occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is a technical object of the present invention to provide a scheduling method and apparatus capable of improving data transmission efficiency.

Disclosure of Invention The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a scheduling method and an apparatus capable of improving data transmission efficiency in consideration of a portable Internet service provision characteristic.

Another object of the present invention is to provide a scheduling method and apparatus capable of improving data transmission efficiency by reducing resources for map message allocation.

According to an aspect of the present invention, a scheduling method includes: scheduling data of a real-time service in a current frame; After scheduling the data of the real-time service, the scheduling of the data of the non-real-time service is performed, and weighting is given when scheduling the data of the non-real-time service to a terminal on which the data of the real-time service is scheduled among a plurality of terminals. It features.

Scheduling method according to an embodiment of the present invention for achieving the above object in the scheduling method of the portable Internet system, based on the data transmission-related elements for the non-real-time service (Proportional Fair queuing formula) Calculating; And scheduling a data burst according to a calculated value of the connection priority function, wherein the priority function is determined differently according to whether or not to allocate a data burst for a service other than the non-real time service.

A scheduling apparatus according to an embodiment of the present invention for achieving the above object includes a transmission expectation generation unit for generating an expected transmission rate of data at a current time point for each connection of the plurality of terminals; An average rate management unit for calculating an average data rate up to now for each connection of the plurality of terminals; A scheduling priority for the connection of the non-real-time service is generated by generating a weight for the terminal that has been scheduled for another connection before scheduling the connection of the non-real-time service among the plurality of terminals, and adding the generated weight to the expected transmission rate. A control unit for generating a value; And a burst allocator for allocating data to a burst area of the frame according to the scheduling performed by the priority value from the controller.

According to an exemplary embodiment of the present invention, data transmission efficiency may be improved by allocating radio resources according to a channel state of a user terminal and a data transmission rate for a predetermined time.

According to an embodiment of the present invention, data transmission efficiency may be improved by reducing resources for map allocation.

According to an embodiment of the present invention, the generation of starvation may be prevented by allocating a radio resource to a user terminal having a poor channel state according to a data rate for a predetermined time.

According to the present invention, data transmission efficiency can be improved by allocating a predetermined radio resource to a user terminal having a good channel state.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention. In the following description, a base station (BS) is a transmitter and a user terminal (MS) is a receiver (DL). However, this is merely exemplary and the roles of the base station and the user terminal for the transmitter or receiver may be switched.

Prior to referring to the drawings, the present invention relates to a scheduling method and apparatus for improving data transmission efficiency in a portable Internet system, the scheduling apparatus of the present invention is included in a base station. Therefore, the components related to the scheduling in the configuration of the base station will be described in detail, detailed description of the other components will be omitted, and the scheduling performed in the base station will be briefly described. Hereinafter, the scheduling apparatus of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a base station 100 including a scheduling apparatus 200 according to an embodiment of the present invention basically selects a radio channel allocated to each user terminal based on feedback information transmitted from the user terminal. Schedule. Here, the scheduling apparatus 200 of the base station 100 first finds a channel having optimal performance for each user terminal and then performs scheduling so that the channel having optimal performance is allocated to the user terminal.

The base station 100 according to an embodiment of the present invention performs scheduling according to the class of the service provided, that is, whether the data burst to be transmitted to the user terminal corresponds to a real time service or a non real time service. In addition, before a data burst is allocated to a connection of a non-real-time service for the same terminal, another connection other than the non-real-time service connection to be allocated to the current frame (that is, a connection of the real-time service) to the map message area. When the data burst is allocated to the MAP_IE in the map message area, the weighting ratio γ is assigned to the data of the non-real time service to increase the expected transfer rate r _i .

Here, the weight γ is added to the expected transmission rate r _i at the present time, which affects the prioritization of burst allocation for a plurality of user terminals or connections. That is, the user terminal given the weight γ has a higher priority for burst allocation of data of the non-real time service in the current frame than other user terminals without the weight γ. That is, the probability that the terminal or connection to which the weight γ is assigned can be assigned a burst. Through this, scheduling is performed so that a predetermined radio resource is allocated not only to a user terminal having a good channel state but also to non-real-time data of a user terminal having a relatively low channel state, and the frame generated by the aforementioned scheduling is allocated to a physical layer. By wireless transmission.

To this end, the base station 100 according to the embodiment of the present invention, as shown in Figure 1, the band signal processor 110, the transmitter 120, the receiver 130, the antenna 140, the map message generator ( 150 and the scheduling device 200.

First, the receiver 130 of the base station 100 converts the signals received through the antenna 140 into baseband signals. For example, the receiver 130 removes and amplifies the noise from the above-described signal for data reception by the base station 100, down converts the amplified signal into a baseband signal, and digitizes the down-converted baseband signal.

In the receiving path, the band signal processor 110 extracts data bits from the digitized signal from the receiver 120 to perform demodulation, decoding, and error correction. The received information is transmitted to an adjacent wired / wireless network (not shown) through an interface (not shown) or transmitted to user terminals serviced by the base station 100 through a transmission path. In addition, the band signal processor 110 encodes input data and control information in the transmission path and outputs the encoded data and control information to the transmitter 120.

The transmitter 120 modulates the burst of data allocated by the burst allocator 250, that is, the encoded voice, data, or control information into a carrier signal having a desired transmission frequency or frequencies, and modulates the modulated carrier signal suitable for transmission. Amplifies to a level and propagates through the antenna 140 to the air. Information on the transmitted data burst is defined in downlink and uplink map messages DL_MAP_IE and UL_MAP_IE in the map message area.

The map message generator 150 generates a downlink map (DL-MAP_IE) message and an uplink map (UL-MAP_IE) in the map message area of the frame based on the data burst allocation information (scheduling information) received from the scheduling apparatus 200. ) Create a message and assign it.

Referring to FIG. 2, an OFDMA frame of a portable Internet system includes a map message area including a configuration information of a frame, a downlink (DL_Link) subframe, and an uplink (UL_Link) subframe.

In general, downlink transmission starts with one preamble symbol, an FCH and downlink map (DL_MAP) message, and data burst (# 1 to #n) symbols, and uplink transmission starts with control symbol transmission. TTG and RTG, which is a guard time for distinguishing uplink and downlink transmission times, are allocated between the downlink and uplink in the middle and at the end of the frame.

The map message generated by the map message generator 150 is composed of a downlink map (DL_MAP) message for downlink and an uplink map (UL_MAP) message for uplink and is allocated to a map message area of a frame.

The downlink map (DL_MAP) message includes information indicating which downlink data bursts transmitted from the base station 100 are data of which user terminal and in which region the data burst of a specific user terminal is located in a downlink frame. . In addition, the uplink map message includes information indicating in which region the data burst of a specific user terminal is located in the uplink bursts transmitted by the user terminals in the uplink frame.

The downlink map message among the map messages includes a downlink map information element (IE) in which information on each data burst is defined for each data burst. Here, the downlink map information element includes the modulation level of the data burst, the starting point (symbol offset and subchannel offset) of the data burst, the length of the data burst (number of symbols and the number of subchannels), and terminal information to receive the data burst. Included. That is, the map message generating unit 150 includes information of each data burst allocated by the scheduling apparatus 200 in a downlink map information element to create a map message. In this case, the map message generator 150 may arrange map information of the corresponding data bursts in the map message in the order in which the data bursts are allocated.

The scheduling apparatus 200 determines which rules to distribute available radio resources of the base station 100 to each terminal, and the uplink subframe and the downlink of the current frame for data transmission and reception of each user every frame. Allocating and managing subchannels by identifying a queue that can be allocated in the entire burst area of the subframe.

 In addition, the scheduling apparatus 200 determines whether a service class provided by the base station 100, that is, data to be transmitted to the user terminal corresponds to a real-time service or a non-real-time service, and according to the determination result, Scheduling for data of non real-time service is performed.

) 대비 현재 시점에 전송 가능할 것으로 예상되는 현재 시점의 기대 전송률(r_i) 즉, 현재까지 전송된 평균 데이터 양[Mbps] 대비 현재 시점의 데이터 기대 전송률(r_i)의 비율이 큰 사용자 단말 즉, 스케줄링 우선 순위 값(P_i)이 큰 사용자 단말(예를 들면 제 1 사용자 단말)에 대하여 비 실시간 서비스의 데이터에 대한 스케줄링의 우선 순위를 부여한다.As disclosed in Equation 2 below, the scheduling apparatus 200 may determine an average transmission rate (T) of the connection (i) of a specific user terminal (for example, the first user terminal) to date.

_I ) a user terminal having a large ratio of the expected data rate r _i , which is expected to be transmitted at the present time, that is, a ratio of the data expected data rate r _i at the present time to the average amount of data transmitted so far [Mbps], A scheduling priority for data of a non real-time service is given to a user terminal (for example, a first user terminal) having a large scheduling priority value P _i .

In addition, when a map information element (MAP_IE) is assigned to a map message area for data of another connection, prior to burst allocation for data of a non-real time service connection for the same terminal, Weight γ is given to the expected transfer rate r _i . This increases the expected transmission rate at the present time, increasing the scheduling priority value (P _i ).

In this way, by assigning the expected transmission rate weight (γ) to the expected transmission rate (r _i ) of the current time point for the same terminal that the burst allocation of other data is made before the burst allocation for the data of the non-real-time service in the current frame, the channel state In addition to a good user terminal, a predetermined radio resource (sub channel) can be allocated to the data of a connection corresponding to a non real-time service of a user terminal having a relatively poor channel state by increasing the priority of data burst allocation. Perform scheduling to ensure

는 사용자 단말의 커넥션 별 평균 데이터 전송률을 의미하고, r_i는 사용자 단말의 현재 시점의 커넥션 별 기대 전송률을 의미하며, γ는 상기 현재 시점의 기대 전송률 r_i에 더해지는 기대 전송률의 가중치를 의미한다.Here, P _i means the burst allocation priority value of the connection (i),

Denotes an average data rate for each connection of the user terminal, r _i means an expected data rate for each connection at the current time of the user terminal, and γ denotes a weight of an expected data rate added to the expected data rate r _i for the current time point.

Here, the expected transmission rate weight γ is determined by Equations 3 and 4 below according to the uplink and the downlink.

Equation 3 is a weight γ added to the expected transmission rate r _i in the uplink of the current frame, and is different from the burst allocation for data of the non-real-time service in the uplink of the current frame with respect to the same UE. When the data burst allocation of the connection is made and the map information element UL_MAP_IE for the other connection is allocated to the map message area, the weight γ according to Equation 3 is added to the expected transfer rate r _i .

In Equation 3, "Size (C)" represents the number of connections to which the allocation of data bursts of non-real-time services is allowed in the current frame, and "Total Available Slot Count" is data of non-real-time services in the current frame. 'UL_MAP_IE' is an uplink map information element for a connection of a non real-time service without considering allocation of an uplink map information element (UL_MAP_IE) for the other connection. In the case of assigning (UL_MAP_IE), this means the total number of slots used in the map message area.

Here, "UL_MAP_IE" in Equation 3 does not mean the number of slots actually required in the map message area when allocating data bursts for connections between real-time services and non-real-time services by the same terminal. Expected data rate r _i ) is a mathematically considered factor to add weight γ to.

In summary, the expected transmission rate weight γ obtained through Equation 3 is not considered in the burst allocation of other connections to the number of slots expected to be transmitted at the present time for each connection of each user terminal. In the case of scheduling only a connection of a non-real time service in a current frame, as the number of slots required for allocation of the UL map information element UL_MAP_IE increases, the expected transmission rate weight γ increases.

In other words, when scheduling only a connection of a non-real time service in a current frame, the smaller the number of slots that are expected to be transmitted at the present time, the larger the map overhead occupies and thus the map information element (MAP_IE) becomes. The expected transmission rate weight γ of the allocated terminal is increased. This means that if scheduling is made for another connection before scheduling the connection of the non-real-time service, the connection of the non-real-time service is different from the connection of the non-real-time service (for example, the connection of the real-time service) without additionally allocating a map information element (MAP_IE). That means you can schedule it together. In this case, data transmission efficiency can be improved by weighting the expected data rate to increase scheduling priority.

Here, the number of slots used for the uplink map information element is set to a fixed value regardless of the state of the terminal. The factor that affects the number of slots is that the map information elements are allocated to the map message area by the data allocation of the real-time service, so that additional allocation of slots is necessary in the map message area when additional data of the non-real-time service is to be allocated. In this case, additional allocation of slots is required in the map message area because no other data is allocated before data allocation of the non-real time service.

Assigning the expected data rate weight (γ) to the data burst allocation of the non-real-time service to the user terminal that has been assigned the data burst of the real-time service is the same for the same user terminal. This is because when the map information elements are allocated, allocating data bursts of the non-real time service together reduces the radio resources required for the map allocation of the data burst corresponding to the non-real time service.

In addition, it is to prevent the occurrence of starvation by allocating a predetermined radio resource to a user terminal having a poor channel state according to a data transmission rate for a predetermined time. Through this, it is possible to improve the data transmission efficiency of the system.

Equation 4 represents the expected transmission rate weight γ of the downlink, and since the factors applied to the uplink in Equation 3 are equally applied to the downlink, the meaning of Equation 4 and a detailed description of each factor Is omitted.

A and β may be adjusted together with the expected transmission rate weights γ according to Equations 3 and 4 to perform scheduling of data bursts corresponding to non real-time services of the plurality of user terminals.

For example, when α is made larger than β, an equal data rate may be allocated to all user terminals to which data bursts of non real-time services are to be allocated.

On the other hand, when β is made larger than α, it transmits to the user terminal (eg, the first user terminal) having the highest expected transmission rate, that is, the CINR, among the plurality of user terminals to which the data burst of the non real-time service is to be allocated. If there is a slot that can be allocated and there is a slot that can be allocated after the slot allocation of the first user terminal, the user terminal (for example, the second user terminal and the third user terminal) of the next rank within the assignable slot range is ordered. Slots can be allocated to be allocated.

To this end, as shown in FIG. 3, the scheduling apparatus 200 includes a service class determination unit 210, a transmission expectation generation unit 220, an average rate management unit 230, a control unit 240, and a burst allocator 250. And a map message confirmation unit 260.

The service class determination unit 210 determines a class of a service provided by the base station 100 to the plurality of user terminals, and transmits the determination result to the burst allocation unit 250 and the control unit 240.

In detail, the scheduling apparatus 200 of the base station 100 according to an embodiment of the present invention may determine whether a data burst to be allocated to a plurality of user terminals corresponds to a real-time service or a non-real-time service. It performs scheduling separately. To this end, the service class determination unit 210 determines the service class of the data bursts allocated to the downlink subframe and the uplink subframe transmitted to each of the plurality of user terminals, and determines the burst assignment unit 250 and the determination result. The control unit 240 transmits.

The burst allocator 250 allocates a data burst to be transmitted to each user terminal in the uplink (receive path) and downlink (transmission path) to the downlink subframe and the uplink subframe, respectively, as shown in FIG. 2. In this case, the size of the data burst to be allocated is determined in consideration of the size of the data to be transmitted, the channel state, and the like, and the data burst to be allocated is assigned to a two-dimensional region defined by time and frequency in each subframe region. .

The burst allocator 250 sequentially allocates downlink data bursts based on the symbol offset. In this case, the downlink data burst may allocate the data burst in a two-dimensional area in the vertical and horizontal directions.

Here, the meaning of allocating data bursts in the vertical direction is to allocate data bursts in a direction in which subchannels increase in a predetermined symbol period, and after allocating data bursts for all subchannels in a predetermined symbol period is completed. This means that data bursts are sequentially allocated from the first subchannel of the next symbol interval.

On the other hand, the meaning of allocating data bursts in the horizontal direction means that data bursts are allocated in a direction in which a symbol increases in a section of a predetermined subchannel, and after allocating data bursts for all symbols in a section of a predetermined channel, the next channel. This means that data bursts are sequentially allocated from the first subchannel of the interval.

In this case, when data bursts are allocated to the downlink subframe, a symbol offset, a subchannel offset, a number of symbols used (No. OFDMA Symbols) and a number of subchannels used (No Assign data bursts to a two-dimensional region defined by Sub Channels.

The burst allocator 250 allocates a data burst of each of the plurality of user terminals to a downlink frame and an uplink subframe, and thus corresponds to a real-time service according to a service class determination result transmitted from the service class determiner 210. The first data burst is allocated to the first burst region of the downlink frame and the uplink frame, and then the data burst corresponding to the non-real time service is allocated to the second burst region except for the first burst region.

Hereinafter, the allocation of the data burst corresponding to the real-time service to the first burst region of the downlink frame and the uplink frame is called first scheduling, and corresponds to the non-real-time service in the second burst region except for the first burst region. Allocating a data burst is defined as second scheduling.

The burst allocator 250 first considers a MAC management message, a UGS service, an ertPS service, and an rtPS service in consideration of data rates, delays, and jitters to be transmitted to a plurality of user terminals. As described above, a first scheduling is performed for allocating data bursts to first burst regions of the downlink frame and the uplink frame with respect to data corresponding to the real-time service.

Here, in the first scheduling for allocating data bursts corresponding to real-time services of a plurality of user terminals, a scheduling method considering data rate, delay, and jitter may be used.

In addition, the burst allocator 250 uses the information from the map message confirming unit 260, the transmission expected value generating unit 220, and the average rate managing unit 230 to be described later after performing the above-described first scheduling. The second scheduling is performed according to the priority value Pi generated by the burst controller 240.

The map message checking unit 260 receives information on whether the map message is allocated to the real-time service data burst from the map message generating unit 150 of the base station 100, and the user is required to allocate the data burst of the non-real-time data. It is checked whether the map message for the data burst of the real-time service is already allocated to the map message area for each terminal, and transmits the confirmation result to the controller 240.

Herein, for example, it is confirmed whether the map message for the data burst of the real-time service is already assigned to the map message area. For example, the map message for the data burst of the real-time service is displayed in the map message area for the first user terminal. This is because when the data bursts of the non-real time services are allocated together, the data bursts of the two services can be allocated without increasing the radio resources in the map message area.

In this case, there is no increase in radio resources because only the duration information is updated in the same map information element MAP_IE, so that the map information element for the data of the real-time service and the non-real-time server can be allocated.

In this case, the expected transmission rate weight γ is assigned to the data burst allocation of the non real-time service to increase the priority of the data burst allocation of the non-real-time service. That is, if map messages are allocated to the data bursts of real-time and non-real-time services of the same user terminal together, data bursts of real-time and non-real-time services can be allocated without increasing the overall map message, thereby improving the overall data transmission efficiency of the system. Can be.

The transmission expectation generation unit 220 is the expected transmission rate of the data of the non-real-time service at the present time, that is, at the current time, for the user terminal in which the data burst of the real-time service is allocated to the first burst region of the frame by the first scheduling. The amount of non-real-time data that can be transmitted is calculated to generate a transmission expectations r _i , and information about the generated transmission expectations is transmitted to the controller 240.

)를 산출하고, 산출된 평균 전송률을 제어부(240)로 전송한다.The average transfer rate management unit 230 transmits the average transfer rate up to now through the data bursts allocated to each of the plurality of user terminals in each frame.

) And transmits the calculated average data rate to the controller 240.

), 현재 프레임에 할당 가능한 총 슬롯 수를 통해 기대 전송률 가중치(γ)를 산출한다. The control unit 240 does not directly apply the transmission expectations ri at the current time point for each of the plurality of user terminals from the transmission expectation generator 220, but applies the equations 3 and 4 to the transmission expectation generator 220. The expected transfer rate ri at the current time point from), and the average transfer rate from the average transfer rate management unit 230 (

), The expected transmission rate weight γ is calculated based on the total number of slots that can be allocated to the current frame.

Here, the weight γ is set to 0 for the non-real-time service of the terminal to which the map information element is not assigned to the map message region before the data allocation of the non-real-time service, and the weight is set to the map message region before the data allocation of the non-real-time service. The non-real-time service of the terminal to which the map information element is assigned is given a weight γ according to Equations 3 and 4 described above.

In addition, the priority value Pi is calculated for each user terminal by adding the previously calculated expected transmission rate weight γ to the transmission expectation value ri at the present time by applying Equation 2 above. The calculated scheduling priority value P _i of each connection of each user terminal is transmitted to the burst transmitter 250.

The burst transmitter 250 allocates a burst of data corresponding to the non-real time service based on the scheduling made according to the scheduling priority value P _i of each connection of the plurality of user terminals from the controller 240.

Here, the second scheduling is performed for allocating a data burst corresponding to the non-real time service after the scheduling of the real time data is performed in the first scheduling step. In particular, the second scheduling of the real time data and the non real time service to the same user terminal is performed. When data is transmitted together, scheduling is performed with a higher priority for data burst allocation of a non real-time service for the corresponding user terminal.

Means of what is here, increasing the priority becomes, the current expected rate weights (γ) of the scheduling priority value (P _i) added to the transfer expected value (ri) of a point increases as in the description of the equation (2) to 4 Therefore, this means that the priority of burst allocation for data of the non-real time service in the current frame is increased.

In the second scheduling, the map message check result for the data burst corresponding to the real-time service from the map message check unit 260, the calculation result of the amount of data that can be transmitted at the present time from the transmission expectation value generation unit 220, and the average transfer rate Scheduling is performed within a range of radio resources that can be allocated in order of the user terminal having the highest priority value Pi calculated from the average data rate from the manager 230 to the present.

Scheduling apparatus 200 according to an embodiment of the present invention including the above-described configuration is a user terminal that requires the allocation of data bursts corresponding to real-time services and non-real-time services, the channel state is relatively compared to other user terminals Even if it is low, the data burst of the non real-time service is scheduled to be allocated. In this way, it is possible to improve the data transmission efficiency of the system by reducing the resources of the map message area for data burst allocation corresponding to the non-real time service. In addition, a predetermined radio resource may be allocated to a user terminal having a good channel state as well as to a user terminal having a poor channel state, thereby preventing the occurrence of a starvation.

In the above-described embodiment, the scheduling apparatus 200 and the map message generator 150 are described as being included in the base station 100 as components that are independent of each other, but these components are integrated into one base station within the base station 100. It may be implemented as a component (eg a scheduler).

4 is a flowchart illustrating a scheduling method according to an exemplary embodiment of the present invention. Hereinafter, a scheduling method according to an exemplary embodiment of the present invention will be described with reference to FIG. 4.

Prior to the description with reference to the drawings, the scheduling method according to an embodiment of the present invention performs scheduling for the connection of the real-time service according to the service class provided by the base station to first allocate the data burst of the real-time service to the burst area of the frame, Then, the present invention relates to a scheduling method for allocating a data burst of a non-real-time service to a remaining burst region by performing scheduling on a connection of a non-real-time service. For the matter of scheduling of a real-time service, a scheduling method according to the prior art is applied. Therefore, a detailed description thereof will be omitted and the scheduling of data corresponding to the non-real time service will be described in detail.

First, classify service classes of data bursts to be allocated to frames for each connection of a plurality of user terminals according to a service class provided by a base station, and prioritize scheduling of data for each connection of the plurality of user terminals according to a classification result of the service classes. The order of transmission is determined by determining the position (S100). Here, in order to determine the scheduling order, scheduling is performed on data corresponding to a real-time service first, and then scheduling is performed on data of a non-real-time service. It is determined according to a predetermined ranking method in consideration of the service class of data to be allocated to the terminal. Subsequently, according to a predetermined scheduling rank determination method, uplink and downlink are classified for each of a plurality of user terminals to allocate respective data bursts corresponding to real-time services to first burst regions of the uplink subframe and the downlink subframe. (S110) First scheduling is performed.

In this case, an uplink map information element UL_MAP_IE and a downlink map information element DL_MAP_IE defining information about data bursts allocated to burst regions of an uplink subframe and a downlink subframe are uplinked and configured for each user terminal. It is assigned to the downlink map message area.

Thereafter, a queue for storing data to be transmitted for each connection of the non real-time service is checked (S120).

Here, the queue stores data of a non-real-time service to be scheduled. If the queue is empty, it means that there is no data of a non-real-time service to be scheduled in the current frame (this frame). In this case, it means that there is non-real time data to be scheduled in the current frame.

Subsequently, in order to sequentially determine the scheduling priority of the entire non-real-time service that has the data to be scheduled, it is checked whether the number of data (i) of the non-real-time service whose weight is calculated in S160 described below exceeds the number of data stored in the queue ( S130). Here, i denotes a variable mathematically considered in order to sequentially determine scheduling priorities for data of all non-real-time services stored in a queue.

Thereafter, the map information element MAP_IE is checked in the downlink map message region DL_MAP and the uplink map message region UL_MAP (S140). Here, the checking of the map information element MAP_IE is for selecting data of the non-real-time service to which the weight γ calculated in S160 will be given among all data of the non-real-time service to be scheduled.

Thereafter, using the check result of S140, it is checked whether the data burst of the real time service is allocated to the specific user terminal (eg, the first user terminal) before the data burst of the non real time service is allocated. That is, it is checked whether the map information element MAP_IE for the data burst of the real-time service is allocated to the downlink map message region DL_MAP and the uplink map message region UL_MAP with respect to the first user terminal (S150). .

As a result of checking in step S150, if the real time service is scheduled before the data scheduling of the non real time service in the current frame and the map information element MAP_IE is allocated to the first user terminal, the controller of FIG. In operation 240, the expected transmission rate weight γ of the uplink is calculated through Equation 3, and the expected transmission rate weight γ of the downlink is calculated through Equation 4 (S160). ).

On the other hand, as a result of confirming in step S150, if the scheduling of the real-time service has not been performed before the data scheduling of the non-real-time service, the weight (γ) value is "0".

를 의미한다.Subsequently, the expected transmission rate weight r γ is added to the expected transmission rate r _i1 from the transmission expectation value generation unit 220 of FIG. 3 to generate a weighted expected transmission rate r _i2 (S170). The weighted expected transmission rate r _i2 generated in S170 is expressed by Equation 2 below.

Means.

Thereafter, by increasing the value of i (S180), the processes of S130 to S170 are sequentially performed for other user terminals and other connections in addition to the first user terminal.

Thereafter, the expected transmission rate r _i1 from the transmission expectation value generation unit 220 is updated to the expected transmission rate r _i2 at the current time point given the weight value γ, and the current transmission time at which the weight γ is given. A second scheduling is performed by allocating a data burst to data of non-real-time services of each of the plurality of user terminals according to the scheduling priority value P _i calculated through Equation 2 by applying the expected transfer rate r _i2 . (S190). Thereafter, according to the scheduling of S190, data burst allocation is performed on the data of the non-real time service (S200).

Here, as shown in Equation 2, the data burst allocation of the non-real-time service is not always performed for the user terminal to which the weight of the expected transmission rate is given, but as shown in Equations 3 and 4, the weight of the expected transmission rate γ is not added. so that relative to the scheduling priority value than the user terminal (P _i) is the probability of large data burst allocation is made becomes very large.

Here, the probability that data burst allocation is made also varies depending on α and β, but the smaller the number of slots that are expected to be transmitted at the present time, the greater the probability that data burst allocation will occur according to the weight γ of the expected data rate. You lose. In addition, as the number of slots required for the allocation of the map information element MAP_IE increases, that is, the number of slots used in the map message area for the allocation of data bursts increases, the probability that a high priority is given during scheduling increases.

Here, the meaning of the large number of slots allocated to the map information element MAP_IE means that the data of the non-real time service is not allocated together with the map information element MAP_IE of the data of the non-real time service and the data of the real time service, as described above. When a map information element (MAP_IE) is separately allocated, this means a relative number of slots additionally required for the map message area. A large number of slots allocated to the map information element (MAP_IE) means that the number of slots used in the burst area for the data burst allocation of the non-real-time service is relatively large, and the number of slots required for the map information element (MAP_IE) is fixed. Has a value.

For example, assuming that there is only one slot to allocate to a non-real-time service on a frame after performing burst allocation on the data of the real-time service in the burst area of the frame, in this case, another connection before data allocation of the non-real-time service is performed. It becomes very important whether or not the map information element (MAP_IE) is allocated.

As described above, when scheduling a connection of a non-real time service to a terminal that has been scheduled for a connection of a real time service, the data of the real time service and the non real time service is increased without increasing the number of slots required in the map message area. Because it can be scheduled together.

On the contrary, if a burst allocation is performed on the data of the real-time service in the burst area of the frame, and there are many slots to be allocated to the non-real-time service on the frame, the map overhead for the slot to be allocated to the data of the non-real-time service ( MAP overhead is not relatively large.

This means that if data bursts corresponding to real-time and non-real-time services are allocated together, data bursts of real-time and non-real-time services can be allocated without increasing the slots required for the allocation of the map information element (MAP_IE). The radio resources required for the map message area can be reduced.

In this case, if the probability of high priority is given to data burst allocation is increased, bursts of data of real-time service and non-real-time service are simultaneously allocated to the same user terminal in the same frame. The allocated radio resources of the map message area can be reduced. This allows more radio resources to be allocated to data bursts within a frame, thereby improving data transmission efficiency. In addition, burst generation may be prevented by assigning a burst to a user terminal having a poor channel state to which a data burst of a non real-time service is allocated.

As a result of checking in S150, when the data burst of the real-time service is not allocated to the first user terminal before the data burst of the non-real-time service is allocated in the current frame, the weight of the expected transmission rate γ is zero in Equation 2 above. Set it. That is, the scheduling priority value P _i is calculated using only the expected transfer rate r _i from the transmission expectation generator 220 at the current time point, and the non-real time service of the corresponding user terminal is calculated according to the calculated P _i value. Perform data burst allocation for the data.

A user terminal that does not have a weighted γ of an expected data rate has a smaller scheduling priority value P _i than a user terminal to which a weighted γ of an expected data rate is given. The probability that a data burst is allocated to a data burst, that is, a low priority is given to a data burst allocation of a non real-time service, is increased. As a result, if the data burst of the real-time service is not allocated before the data burst of the non-real-time service in the current frame, the probability that the allocation of the data burst in the current frame is suspended becomes very large.

Here, when a data burst of a non-real time service is to be allocated to a user terminal to which a data burst of a real time service is not allocated, the data burst allocation of the non real time service is not always suspended, and the calculated scheduling priority value P _i ), the probability of being allocated a data burst of a non real-time service in the current frame is reduced. When the user terminal is also assigned a data burst of the real-time service in a frame other than the current frame, the scheduling priority value P _i becomes high, so that the probability of allocating the data burst of the non-real-time service in the frame becomes high. .

Through the above-described second scheduling, it is possible to prevent radio resources from being consumed in the map message area for burst allocation of the user terminal that wants to transmit only non-real-time service data in one frame, thereby allowing more radio resources to burst in the data within the frame. Can be assigned.

The present invention according to the embodiment relates to a scheduling method that considers the map overhead (MAP overhead) in addition to the factors related to the actual data transmission (expected data rate, average data rate), and manages the radio resources allocated to data transmission for efficient scheduling The weight is calculated according to the ratio of radio resources allocated to the overhead, and the scheduling weight is increased by adding the calculated weight to the expected transmission rate.

The scheduling method according to the embodiment of the present invention can reduce the management overhead if the necessary management overhead is large while the resources allocated for data transmission are small (for example, the map information element (MAP_IE) for the real-time service is already available. ) Is already allocated, so that no additional allocation for the map information element of the non-real-time service is needed, thereby improving the data transmission efficiency by increasing the priority of data scheduling of the corresponding terminal. In the above description, the PF scheduling has been described as an example, but the scheduling method of the present invention can be applied to other scheduling methods as well as the PF scheduling method.

The above-described scheduling method may be implemented in the form of a program that can be executed using various computer means. A program for performing the scheduling method may be a recording medium (eg, a hard disk, A recording medium such as a CD-ROM, a DVD, a ROM, a RAM, or a flash memory. It also includes those implemented in the form of carrier waves (eg, transmission over the Internet). The computer-readable recording medium may be distributed and formed in a computer system connected via a network.

Configuration and operation as described above is not limited to the claims of the present invention as an embodiment, and various changes and modifications are possible within the scope of not changing the technical spirit of the present invention in the field to which the present invention belongs. It is obvious to those who are engaged.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above detailed description should not be interpreted as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

1 is a diagram illustrating a base station including a scheduling apparatus according to an embodiment of the present invention.

2 is a diagram illustrating a frame structure of a mobile internet system.

3 is a diagram illustrating a configuration of a scheduling apparatus according to an embodiment of the present invention.

4 is a flowchart illustrating a scheduling method according to an embodiment of the present invention.

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

100: base station 110: band signal processing unit

120: transmitter 130: receiver

140: antenna 150: map message generation unit

200: scheduling device 210: service class determination unit

220: transmission expected value generation unit 230: average transmission rate management unit

240 control unit 250 burst allocation unit

260: map message confirmation unit

Claims (18)

Scheduling data of the real-time service in the current frame; After scheduling the data of the real-time service, the scheduling of the data of the non-real-time service is performed, and weights are assigned when scheduling the data of the non-real-time service to a terminal on which the data of the real-time service is scheduled among a plurality of terminals, The scheduling method of the non-real-time service data scheduling method characterized in that it is determined in inverse proportion to the average amount of data transmission to date and in proportion to the amount of data transmission that can be expected at the present time. delete The method of claim 1, Scheduling for the data of the non real-time service is The priority method is determined according to the channel state of the terminal, the average data rate for a predetermined time and the expected data rate at the present time. The method of claim 3, wherein The scheduling method of claim 1, wherein the priority of the scheduling for the data of the non-real-time service of the terminal that the expected rate is higher than the average rate is increased. The method of claim 1, wherein the weight is The scheduling method is calculated based on the number of slots required for allocation of the map information element (MAP_IE). The method of claim 1, wherein the weight is Scheduling method, characterized in that calculated based on the number of slots expected to be transmitted at the current time point for each connection of the terminal. In the scheduling method of a portable Internet system, Calculating a priority function for each connection based on data transmission related factors for the non-real-time service; And Scheduling a data burst according to a calculated value of the connection priority priority function; The priority function may be determined differently according to whether or not to allocate a data burst for a service other than the non-real time service. 8. The method of claim 7, wherein the data transfer related elements are Average data rate to date; And A scheduling method comprising the expected data rate that can be transmitted in the current frame. The method of claim 8, And the priority function is further obtained by using a weight factor based on a control message size when a data burst for another service is allocated. The method of claim 7, wherein The priority function is obtained by using the overhead message size required for data transmission further. A transmission expectation generation unit for generating an expected transmission rate of data at a current time point for each connection of a plurality of terminals; An average rate management unit for calculating an average data rate up to now for each connection of the plurality of terminals; A weight is generated for a terminal that is scheduled for another connection before scheduling a connection of a non-real time service among the plurality of terminals, and the scheduling weight for the connection of the non-real time service is added by adding the generated weight to the expected transmission rate. A controller for generating a rank value; And a burst allocator for allocating data to the burst area of the frame according to the scheduling performed by the priority value from the controller. The method of claim 11, And a map message checking unit for confirming whether a map information element for the other connection is allocated to a map message area before scheduling the connection of the non-real-time service. The method of claim 11, And a service class determination unit for determining a service class of data for each connection of the terminal. The method of claim 11, wherein the control unit And generate the scheduling priority value based on the data expected data rate and the data average data rate. The method of claim 11, wherein the control unit The scheduling apparatus, characterized in that for generating the scheduling priority value further using the size of the overhead message required for data transmission. The method of claim 11, wherein the control unit And generating the weight based on the expected data rate expected to be transmitted at the current time point and the number of slots required in the map message area for each connection of the terminal. The method of claim 11, wherein the weight is And calculating the number of slots required in the map message area for the allocation of the map information elements. The method of claim 11, wherein the control unit And a weighting value corresponding to “0” is generated when scheduling of the other connection is not performed before scheduling of the connection of the non real-time service.

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