KR101390314B1 - Apparatus and method for scheduling in mobile communication system - Google Patents

Abstract

The present invention relates to a scheduling in a mobile communication system, and stores a count value of each terminal, and compares the count value of the terminal by comparing the amount of resources allocated to the virtual scheduling result with the total scheduling and the amount of resources allocated to the actual scheduling result. A management unit for updating, a determination unit for determining a scheduling priority of each terminal according to a scheduling scheme using a count value updated by the management unit, and sequentially assigning resources to each terminal according to the scheduling priority And a resource amount allocated as a result of the virtual scheduling, on the assumption that the scheduling priority of each terminal is the highest, wherein the scheduling result and the available resource are used when scheduling. Counter value is adjusted by comparing scheduling results As a result, fairness and wireless capacity for each terminal and service can be increased.

Scheduling, Counter, Round Robin, Proportional Fair

Description

Scheduling device and method in mobile communication system {APPARATUS AND METHOD FOR SCHEDULING IN MOBILE COMMUNICATION SYSTEM}

1 is a block diagram of a base station in a mobile communication system according to the present invention;

2 is a block diagram of a scheduler in a mobile communication system according to the present invention; and

3 is a diagram illustrating a scheduling procedure of a base station in a mobile communication system according to an embodiment of the present invention.

The present invention relates to a mobile communication system, and more particularly, to a scheduling apparatus and method using a counter in a mobile communication system.

In a voice communication-oriented mobile communication system, since radio resources are exclusively occupied for each terminal, each terminal can receive a service without a time delay at an almost constant transmission rate. However, in a next generation mobile communication system such as a High Speed Downlink Packet Access (HSDPA) system, radio resources are allocated differently according to a service to be provided by each terminal, and a user may receive various services at high speed. want. Therefore, in the next generation mobile communication system, it is very important to efficiently allocate and allocate radio resources to a plurality of terminals and services.

Scheduling techniques for properly allocating the radio resources include a round robin method, a maximum quality (Max C / I) method, and a proportional fair method. The round robin method is a method of maximizing fairness by sequentially allocating resources to terminals and services managed by a base station, and the maximum quality method maximizes radio capacity by allocating resources to terminals having the best channel condition. That's the way. In addition, the proportional fair method is a method in which both fairness and wireless capacity are taken into consideration by taking advantage of both the round robin method and the maximum quality method.

Counters are used to ensure fairness in the round robin and proportional fair methods. The counter records the number of times that each terminal is allocated a resource, and the base station determines that fairness is secured as the counter values of all terminals are leveled. That is, the counter increments the counter value of the terminal to which the resource is allocated by '1'.

However, terminals are competitively allocated limited resources in the next generation wireless communication system. That is, a relatively low priority terminal is allocated resources within the remaining resource range except for resources that have already occupied resources by the high priority terminal. In addition, when there are few remaining allocable resources, the terminal having a poor channel state is difficult to perform communication using less resources, so that a terminal having a relatively good channel state is inevitably allocated resources. As a result, a counter value of a terminal having a good channel state increases, and a scheduling priority of the terminal having a good channel state decreases. Accordingly, the terminal having a good channel state is more likely to be allocated resources in a situation where there are few resources remaining in the next scheduling.

As described above, irrespective of the resource situation that can be allocated in the mobile communication system, fixed use of the increment of the counter value does not guarantee fairness of radio resource allocation, and there is a problem in that the total radio capacity of the system is lowered.

Accordingly, an object of the present invention is to provide an apparatus and method for ensuring fairness of radio resource allocation in a mobile communication system and preventing degradation of overall system radio capacity.

Another object of the present invention is to provide an apparatus and method for determining scheduling priority in consideration of available radio resources in a mobile communication system.

According to a first aspect of the present invention for achieving the above object, in a mobile communication system, a base station apparatus stores a count value of each terminal, and allocates an amount of resources and an actual scheduling result allocated to a virtual scheduling result using all resources at every scheduling. A management unit for updating the count value of each terminal by comparing the amount of resources, a determination unit for determining a scheduling priority of each terminal using the count value, and sequentially assigning resources to each terminal according to the scheduling priority order. It characterized in that it comprises an allocator.

According to a second aspect of the present invention for achieving the above object, a scheduling method of a base station in a mobile communication system, the process of determining the scheduling priority using the count value of each terminal, and each terminal according to the scheduling priority And a step of allocating a resource to the resource and updating the count value of the terminal by comparing the virtual scheduling result with the entire resource and the actual scheduling result.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, a description will be given of a technique for determining a scheduling priority of a terminal in consideration of available radio resources in a mobile communication system. The present invention is described using a High Speed Downlink Packet Access (HSDPA) system as an example, and may be equally applicable to other types of mobile communication systems.

First, the count value update method proposed by the present invention will be described.

The count value update method proposed by the present invention is a method of adjusting an increase of the count value in consideration of available radio resources during scheduling. Herein, the available radio resources mean resources other than those allocated to terminals having a higher scheduling priority than the arbitrary terminals, assuming an arbitrary terminal. In other words, the available radio resource means a candidate resource that can be allocated to the arbitrary terminal. Therefore, the lower the scheduling priority, the smaller the amount of available radio resources.

A terminal that is not the terminal with the highest scheduling priority is allocated a resource in a situation in which some resources are allocated to a terminal having a high scheduling priority, that is, when there are less available resources than all resources. In general, in the above-described situation, the amount of resources actually allocated to the terminal is smaller than the amount of resources allocated when the scheduling priority of the terminal is the highest. Therefore, in the present invention, the count value of the terminal is updated as shown in Equation 1 according to the ratio of the resource amount allocated as a result of the virtual scheduling and the resource amount allocated as a result of the virtual scheduling.

In Equation 1, Count _n represents an nth updated count value, Resource _real represents an amount of resources allocated as a result of actual scheduling, and Resource _virtual represents an amount of resources allocated as a result of virtual scheduling.

At this time, if the count value continues to accumulate, an overflow occurs. Therefore, in order to prevent the overflow, the count value may be used as an average of ratios calculated at every scheduling. When the count value is an average of the ratios, the count value is updated by averaging a predetermined number of ratios as shown in Equation 2 below or calculating a cumulative average as shown in Equation 3 below.

In Equation 2, Count _n is an nth updated count value, Resource _{real, m} is an amount of resources allocated to a real scheduling result at m-th scheduling, and Resource _{virtual , m} is a virtual scheduling result at m-th scheduling The amount of resources, k represents the number of arbitrary averaged elements.

In Equation 3, Count _n is an nth updated count value, α is an average weighted value, Resource _real is an amount of resources allocated as a result of an actual scheduling, and Resource _virtual is an amount of resources allocated as a result of a virtual scheduling.

Here, the amount of resources means that the number of available codes (OVSF: Orthogonal Variable Spreading Factor), power size, modulation and demodulation scheme, and transmission data block size are included. And, if actually implemented, the resource amount may be calculated by selecting only one of the available code number, power size, modulation and demodulation scheme, and transmission data block size, or combining a plurality of them.

Hereinafter, a configuration and an operation procedure of a base station for updating a count value and performing scheduling according to the above-described scheme will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a base station in a mobile communication system according to the present invention.

As shown in FIG. 1, the base station includes a data buffer 101, an encoder 103, a spreader 105, a modulator 107, a radio frequency (RF) transmitter 109, and a scheduler 111. It is composed.

The data buffer 101 stores data to be transmitted to the terminals. Data stored in the data buffer 101 is output for transmission when scheduled by the scheduler 111. The encoder 103 encodes the bit string provided from the data buffer 101 according to the corresponding scheme. The spreader 105 spreads the bit string provided from the encoder 103 in units of chips by using a spreading code assigned to each terminal. The modulator 107 generates a complex symbol by modulating the bit stream spread in units of chips provided from the spreader 105 in a corresponding manner. The RF transmitter 109 converts and amplifies a complex symbol provided from the modulator 107 into an RF band signal and transmits the same through an antenna.

The scheduler 111 performs scheduling for transmitting data stored in the data buffer 101. In other words, the scheduler 111 allocates radio resources to be used to transmit data to each terminal. In this case, the radio resource allocation is performed according to a round robin method or a proportional fair method. In particular, according to the present invention, the scheduler 111 manages a count value of each terminal in consideration of available radio resources and performs scheduling. Here, in the case of performing the proportional fair scheme, although not shown, the base station includes a feedback receiver for receiving feedback of channel quality information from the terminal. The detailed configuration of the scheduler 111 will be described with reference to FIG. 2.

2 is a block diagram of a scheduler in a mobile communication system according to the present invention.

As shown in FIG. 2, the scheduler 111 includes a count value managing unit 201, a priority determining unit 203, and a resource allocating unit 205.

The count value management unit 201 stores and updates the count value of each terminal for determining the priority of scheduling. In other words, the count value management unit 201 increases the count value of the terminal to which the resource is allocated through scheduling. Here, the increment of the count value is a ratio of the resource amount allocated as a result of the actual scheduling and the resource amount allocated as a result of the virtual scheduling assuming that the available resources are all resources. In this case, since the overflow occurs when the count value continues to accumulate, the count value management unit 101 may use the average of the increments calculated at every scheduling as the count value.

In addition, the count value management unit 201 updates the count value of the unscheduled terminals. That is, the base station updates the count value of the unscheduled terminals according to the scheme by setting the actual scheduled resource to '0'. In this case, when the count value is a cumulative value of the ratio, '0' is added, so the count value management unit 201 does not need an operation for updating the count value. On the other hand, when the count value is the average of the ratios, the count value management unit 201 recalculates the average including '0'.

The priority determiner 203 determines the scheduling priority with reference to the count value of each terminal stored in the count value manager 201. In other words, the priority determiner 203 determines whether to schedule data for which service flow of which terminal among data stored in the data buffer 101. For example, when the scheduler 111 is a round robin scheduler, the priority determiner 203 gives a high scheduling priority to a terminal having a small count value stored in the count value manager 201. In addition, when the scheduler 111 is a proportional fair scheduler, the priority determiner 203 determines scheduling priority with reference to channel quality values of respective terminals. In other words, the priority determining unit 203 is the count value of the result (Q / Count) or the count value of a predetermined number of exponent product obtained by multiplying the reciprocal with the channel quality value (Q) of (Count) (Count ^k, Where k is a positive integer) and the channel quality is multiplied by a predetermined number of times (Q ^l , where l is a positive integer), resulting in a high value of the terminal (Q ^l / Count ^k ). Give scheduling priority. In this case, the referred channel quality value may be used as an average value of a value fed back a predetermined number of times or may be used as a value calculated as in Equation 4 below.

In Equation 4, Q _n ^Use denotes a channel quality value used in determining an nth priority, α denotes an averaging weight, and Q _n ^Feedback denotes an nth feedback channel quality value.

The resource allocator 205 allocates resources for transmitting data of a corresponding terminal and a service according to the scheduling priority determined by the priority determiner 203. In addition, the resource allocator 205 virtually allocates assuming a situation in which no resource allocation is performed at the same time that the resources to be used are actually used, that is, all resources are available, and is allocated as a result of the actual scheduling. The resource amount information and the resource amount information allocated as a result of the virtual scheduling are provided to the count value management unit 201.

3 illustrates a scheduling procedure of a base station in a mobile communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the base station determines whether the scheduling period is in step 301.

If the scheduling period, the base station proceeds to step 303 to determine the scheduling priority according to the count value of each terminal. In this case, when the round robin scheduling is performed, the smaller the count value, the higher the priority of the terminal. Alternatively, in the case of performing a proportional fairing scheme, the result of multiplying the count value (Count) by the channel quality value (Q) (Q / Count) or the count value by a predetermined number of times exponential product (Count ^k , Where k is a positive integer) and the channel quality is multiplied by a predetermined number of exponents (Q ^l , where l is a positive integer), resulting in a higher terminal (Q ^l / Count ^k ). Has priority. In this case, the channel quality value may be used as an average value of a value fed back a predetermined number of times or may be used as a value calculated as in Equation 4.

After determining the scheduling priority, the base station proceeds to step 305 to schedule transmission data of the terminal having the highest priority. In other words, the base station allocates resources for transmitting the transmission data of the terminal having the highest priority.

After allocating the resource, the base station proceeds to step 307 and calculates the ratio of the amount of resources to be allocated when scheduling using all resources and the amount of resources allocated as a result of the actual scheduling in step 305. That is, the base station calculates an increase in the count value.

In step 309, the base station updates the count value of the terminal according to the calculated ratio. For example, if the count value is simple cumulative of the ratio, the base station adds the ratio to the count value. Or, if the count value is an average of the ratios, the base station recalculates the average including the ratios.

After updating the count value, the base station proceeds to step 311 to determine whether additional scheduling is possible. That is, the base station checks whether allocable resources remain.

If the additional scheduling is possible, the base station returns to step 305 to schedule transmission data of the highest priority terminal among the unscheduled terminals.

On the other hand, if the additional scheduling is not possible, the base station proceeds to step 313 to terminate the scheduling and update the count value of the unscheduled terminals. That is, the base station updates the count value of the unscheduled terminals according to the scheme by setting the actual scheduled resource to '0'. In this case, when the count value is a cumulative value of the ratio, '0' is added, and thus, the base station does not need an operation for updating the count value. On the other hand, when the count value is the average of the ratios, the base station recalculates the average including '0'.

In step 315, the base station transmits the scheduled data.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, in the mobile communication system, a counter value is adjusted by comparing a scheduling result using all resources and a scheduling result using available resources, thereby increasing fairness and wireless capacity for each terminal and service.

Claims (27)

A base station apparatus in a mobile communication system, A management unit for storing a count value of each terminal, and updating the count value of each terminal by comparing the amount of resources allocated to the virtual scheduling result with the amount of resources allocated to the actual scheduling result for each scheduling; A determination unit which determines a scheduling priority of each terminal according to a scheduling scheme by using the count value updated by the management unit; An allocation unit for allocating resources to the terminals sequentially according to the scheduling priority;  The amount of resources allocated as a result of the virtual scheduling is an amount of resources allocated on the assumption that the scheduling priority is highest for each terminal. The method according to claim 1, The amount of resources, And at least one of available number of available variable spreading factor (OVSF), power size, modulation and demodulation scheme, and transmission data block size. The method according to claim 1, The management unit, characterized in that for updating the count value as shown in the following formula,

Here, Count _n is the n-th updated count value, Resource _real is the amount of resources allocated as a result of the actual scheduling, Resource _virtual represents the amount of resources allocated as a result of the virtual scheduling. The method according to claim 1, The management unit, characterized in that for updating the count value as shown in the following formula,

Here, Count _n is the n-th updated count value, the Resource _{real , m} is the amount of resources allocated as a result of the m-th actual scheduling, Resource _{virtual , m} is the amount of resources allocated as the m-th virtual scheduling, k is any averaging element Indicates the count. The method according to claim 1, The management unit, characterized in that for updating the count value as shown in the following formula,

Here, Count _n is the n-th updated count value, α is the averaging weight, Resource _real is the amount of resources allocated as a result of the actual scheduling, Resource _virtual represents the amount of resources allocated as a result of the virtual scheduling. The method according to claim 1, The determination unit, characterized in that to give a higher scheduling priority to the terminal as the inverse of the count value. The method according to claim 1, The receiver further includes a feedback unit for receiving the channel quality information. The determining unit, characterized in that to give a higher scheduling priority to the terminal as the product of the inverse of the count value and the channel quality value. 8. The method of claim 7, And the channel quality value is an average value of channel quality fed back over a predetermined number of times. 8. The method of claim 7, Wherein the channel quality value is a value calculated as in the following equation,

Here, Q _n ^Use is a channel quality value used when determining the nth priority, α is an averaging weight, and Q _n ^Feedback represents an nth feedback channel quality value. The method according to claim 1, The receiver further includes a feedback unit for receiving the channel quality information. The determining unit may assign a higher scheduling priority to a corresponding terminal as a product of an inverse number of an index product multiplied by a predetermined number of times and an index product of a channel quality value by a predetermined number of times. 11. The method of claim 10, And the channel quality value is an average value of channel quality fed back over a predetermined number of times. 11. The method of claim 10, Wherein the channel quality value is a value calculated as in the following equation,

Here, Q _n ^Use is a channel quality value used when determining the nth priority, α is an averaging weight, and Q _n ^Feedback represents an nth feedback channel quality value. The method according to claim 1, The allocator provides an actual scheduling result and a virtual scheduling result using all resources to the management unit. The method according to claim 1, A buffer for outputting stored data according to the scheduling result; And a communication unit for converting the data from the buffer into a signal and transmitting the signal. In the scheduling method of a base station in a mobile communication system, Storing the count value of each terminal and updating the count value of each terminal by comparing the virtual scheduling result with the entire resource and the actual scheduling result at every scheduling; Determining a scheduling priority of each terminal according to a scheduling method using the updated count value of each terminal; Allocating resources to the respective terminals according to the scheduling priority; The resource amount allocated as a result of the virtual scheduling is a resource amount allocated on the assumption that the scheduling priority is highest for each terminal. 16. The method of claim 15, The amount of resources, And at least one of available number of available variable spreading factor (OVSF), power size, modulation and demodulation scheme, and transmission data block size. 16. The method of claim 15, The count value is updated, as in the following formula,

Here, Count _n is the n-th updated count value, Resource _real is the amount of resources allocated as a result of the actual scheduling, Resource _virtual represents the amount of resources allocated as a result of the virtual scheduling. 16. The method of claim 15, The count value is updated, as in the following formula,

Here, Count _n is the n-th updated count value, the Resource _{real , m} is the amount of resources allocated as a result of the m-th actual scheduling, Resource _{virtual , m} is the amount of resources allocated as the m-th virtual scheduling, k is any averaging element Indicates the count. 16. The method of claim 15, The count value is updated, as in the following formula,

Here, Count _n is the n-th updated count value, α is the averaging weight, Resource _real is the amount of resources allocated as a result of the actual scheduling, Resource _virtual represents the amount of resources allocated as a result of the virtual scheduling. 16. The method of claim 15, Determining the scheduling priority, Calculating the inverse of the count value of each terminal; The greater the inverse number, characterized in that it comprises the step of assigning a higher scheduling priority to the terminal. 16. The method of claim 15, Determining the scheduling priority, Calculating a product of a reciprocal of a count value of each terminal and a channel quality value; And giving a higher scheduling priority to a corresponding UE as the product of the inverse of the count value and the channel quality value increases. 22. The method of claim 21, Wherein the channel quality value is an average value of channel quality fed back over a predetermined number of times. 22. The method of claim 21, The channel quality value is a value calculated as in the following equation,

Here, Q _n ^Use is a channel quality value used when determining the nth priority, α is an averaging weight, and Q _n ^Feedback represents an nth feedback channel quality value. 16. The method of claim 15, Determining the scheduling priority, Calculating a product of a reciprocal of a value obtained by exponentially multiplying a count value of each terminal by an exponent multiplied by a channel quality value a predetermined number of times; And giving a higher scheduling priority to a corresponding terminal as the product of the inverse of the count value multiplied by the predetermined number of times and the channel quality value by the predetermined number of times is multiplied. 25. The method of claim 24, And the channel quality value is an average value of channel quality fed back over a predetermined number of times. 25. The method of claim 24, The channel quality value is a value calculated as in the following equation,

Here, Q _n ^Use is a channel quality value used when determining the nth priority, α is an averaging weight, and Q _n ^Feedback represents an nth feedback channel quality value. 16. The method of claim 15, After the scheduling is completed, converting the scheduled data into a signal and transmitting the signal.

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