KR20190087077A - Load balancing method and apparatus for communication system with carrier aggregation technology - Google Patents

Abstract

The present invention relates to a load balancing method for a communication system applied with a carrier integration technology, which dynamically controls traffic distribution for each band of a terminal based on a load for each component carrier and carrier integration combination information for each terminal, to uniformly balance the load of each of the component carriers integrated into one and to increase a transmission speed experienced by a user. The present invention also relates to an apparatus thereof. According to the present invention, the load balancing method comprises: a step of collecting average load information for each of the component carriers used for the communication system applied with the carrier integration technology; and a step of accessing the communication system to use an average load for each component carrier to a terminal allocating carrier integration combination thereto so as to dynamically distribute a traffic to each component carrier included in the carrier integration combination, thereby minimizing a traffic transmission time of the terminal or load distribution among component carriers.

Description

Technical Field [0001] The present invention relates to a load balancing method and apparatus for a communication system to which a carrier aggregation technology is applied,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to load balancing in a communication system employing Carrier Aggregation (CA) technology, and more particularly to a load balancing method in which a load of each of a plurality of carrier waves bundled is uniformly maintained, To a load balancing method in a communication environment to which a carrier aggregation technology is applied and an apparatus therefor.

Due to the development of information and communication technology, the use of personal mobile communication terminals has increased rapidly, and the amount of data used by mobile communication subscribers has increased exponentially as the amount of content available through mobile communication terminals has increased It is true.

Accordingly, as a method for providing a service having a higher transmission rate to mobile communication subscribers, a CA technology in which two or more frequency bands are bundled and used at the same time is used.

CA technology refers to a technique of aggregating a plurality of component carriers (CCs) to form a single broadband. Since the width of the frequency band is directly related to the data transmission speed, a plurality of frequency bands are grouped together using CA technology as one wide frequency band, so that a mobile communication subscriber can receive a higher quality mobile communication service.

For example, when communicating with a terminal using two frequency bands of 850 MHz and 1.8 GHz, it was possible to communicate up to 75 Mbps through a single frequency band of 850 MHz or 1.8 GHz. And can communicate with a maximum transmission rate of 150 Mbps. At this time, since the coverage per frequency band is different, the terminal can use 850 MHz and 1.8 GHz simultaneously, or can communicate with a single band of either 850 MHz or 1.8 GHz, depending on the position and radio wave reception state.

The mobile communication network based on the CA technology can be variously configured according to the carrier coverage and user policy. 1 illustrates various network configurations based on a CA technology combining 850 MHz (F1) and 1.8 GHz (F2). For example, a solid line indicates communication coverage for a frequency band of 850 MHz, Indicates the communication coverage by the frequency band of 1.8 GHz.

Figure 1 (a) shows that the entire coverage of the F2 frequency overlaps with coverage of the F1 frequency, which in this case can improve the overall throughput within the coverage, Figure 1 (b) Direction can be directed to the boundary of the F1 cell to improve the edge throughput of the F1 cell. FIG. 1 (c) shows the F2 cell as the RRH (hot spot) region of the F1 cell Remote radio head) cell to improve the throughput of the hot spot area.

These CA technologies are defined as standards. Specifically, several carriers in the 1.4, 3, 5, 10, 15, and 20 MHz bandwidth defined in LTE are defined as component carriers (CC) in the LTE-A standard. And defines the CA technologies to be used simultaneously by grouping these CCs. An intra-band CA (intra-band CA) that combines carriers existing in the same service band and an inter-carrier that combines carriers existing in different service bands Band CA (Inter-band CA) and frequency-specific configurable information.

Therefore, under the communication environment to which the CA technology is applied, the mobile communication terminal of each individual subscriber can perform data communication with the base station by selecting a combination of the frequency bands supported by the subscriber, Each type can be different. In such a situation, a situation may arise in which the load imbalance among a plurality of frequency bands used by the mobile communication system, that is, the number of subscribers using the frequency band at a specific time point differs for each band.

However, in the current mobile communication system, when the carrier aggregation combination is selected to reduce the complexity of the base station implementation, the traffic to be transmitted by the terminal is simply allocated in proportion to the bandwidth for each band. Therefore, There is a problem that the transmission speed varies.

In order to solve such a problem, various schemes have been studied. For example, when an arbitrary terminal is connected and a carrier aggregation combination of the terminal is selected, an effective load for each band at that point is calculated A method of selecting a carrier aggregation combination that can minimize the variance of the effective load values of the bands has been proposed. In this scheme, the effective load value of an arbitrary band can be set to be proportional to a value obtained by dividing the number of terminals existing in the corresponding band by the bandwidth of the corresponding band.

Frequency band
(Band) Bandwidth
(BW) Number of terminals
(UE) Effective load (UE / BW) B1 10 8 0.8 B3 20 10 0.5 B5 10 5 0.5 B7a 20 3 0.15 B7b 10 One 0.1 5CC load average 0.41 5CC load deviation 0.083

For example, as shown in Table 1, when the effective load is calculated for each frequency band, the 3 CA terminals having the P cell of the frequency band B1 are newly connected, and the carrier aggregation combinations (B1, B3 , B5), (B1, B3, B7a) and (B1, B3, B7b), considering the dispersion of the effective load values, not simply the carrier aggregation combination for maximizing the bandwidth, To select the carrier aggregation combinations (B1, B3, B7b) that enable load distribution. By this selection, the effective load is varied as follows.

Frequency band
(Band) Bandwidth
(BW) Number of terminals
(UE) Effective load (UE / BW) B1 10 8.333 0.833 B3 20 10.333 0.517 B5 10 5 0.5 B7a 20 3 0.15 B7b 10 1.333 0.1333 5CC load average 0.427 5CC load deviation 0.085

The above scheme can achieve a certain band-by-band load distribution when the terminal supports various carrier aggregation combinations considering the effective load. However, it is difficult to expect a high load balancing performance in a situation where the majority of terminals support the same carrier aggregation combination. Basically, in an environment in which a plurality of bands can be used by carrier aggregation technology, There is a problem that load balancing between the bands can not be sufficiently achieved by a method of changing only the carrier aggregation combination of the terminals.

Korean Patent Laid-Open No. 10-2015-0077666, July 8, 2015 (Title: Terminal Access Control Method and Device for Effective Resource Utilization in a Base Station of a Mobile Communication System Supporting Carrier Aggregation Function)

The present invention has been proposed to solve the load unbalance problem for each element carrier in a mobile communication system employing CA technology, and more particularly, to provide a method and apparatus for dynamic allocation of traffic distribution of each terminal by using load of each element carrier and carrier aggregation information of each terminal And to provide a load balancing method and apparatus for a communication system to which a carrier wave integration technique is applied to improve a user's perceived transmission rate by keeping the load of each of a plurality of element carrier waves uniformly maintained.

As a means for solving the above-mentioned problems, the present invention provides a method for processing a carrier wave, comprising: collecting average load information for each of a plurality of element carriers used in a communication system to which a carrier wave integration technology is applied; And

And an element included in the carrier aggregation combination for minimizing the traffic transmission time of the terminal or minimizing the load dispersion between the element carriers using the average load for each element carrier for the terminal allocated to the carrier aggregation combination connected to the communication system, And distributing the traffic dynamically on a carrier-by-carrier basis. The present invention provides a load balancing method for a communication system to which a carrier aggregation technique is applied.

The method according to the present invention may further include scheduling a traffic transmission of the UE based on the distribution result of the traffic.

According to another aspect of the present invention, there is provided a method for allocating traffic, the method comprising the steps of: confirming whether allocation of a carrier aggregation combination is performed according to a connection request of a terminal before distributing the traffic, And may perform the traffic distribution to terminals that are assigned a carrier aggregation combination by a request.

Further, the method according to the present invention may further comprise confirming whether the carrier aggregation combination of the already-connected terminals is changed before distributing the traffic, and the distributing the traffic may include: And perform the traffic distribution to the changed terminal.

In addition, the method according to the present invention further comprises the steps of periodically confirming an average load per element carrier used in the communication system, prior to distributing the traffic; Confirming whether the average load per element carrier exceeds a predetermined threshold; And extracting a terminal to perform the traffic distribution according to a carrier aggregation combination and a traffic amount of the terminal if at least one element carrier having an average load of the element carriers used in the communication system exceeds the threshold value , And distributing the traffic may allow the extracted terminal to perform the traffic distribution.

In addition, in the method according to the present invention, the step of distributing the traffic may include: estimating an expected load amount for each element carrier based on an average load of each element carrier and a carrier aggregation combination of the terminal; Calculating a traffic allocation value for each of the element carriers that minimizes the variance of the predicted load amount per element carrier; And distributing the traffic of the terminal according to the calculated traffic allocation value for each element carrier, or based on the estimated load of each element carrier and the carrier combination of the terminal, Calculating a different traffic allocation value; And distributing the traffic of the terminal according to the calculated traffic allocation value for each element carrier.

In addition, the present invention provides, as another solution to the above-mentioned problems, an information collection module for collecting the number of users and band information for each of a plurality of element carriers or the average load information for each of a plurality of element carriers used in a communication system to which a carrier wave integration technology is applied; A carrier aggregation combination selection module for selecting a carrier aggregation combination for terminals connected to the communication system; A traffic distribution module for distributing traffic for each element carrier included in the selected carrier aggregation combination so that the transmission time of the terminal is minimized or the load distribution between element carriers is minimized by using an average load for each element carrier; And a scheduling module for scheduling a traffic transmission of the MS based on the traffic distribution value. The load balancing device for a communication system to which the carrier aggregation technology is applied is provided.

In the load balancing apparatus according to the present invention, the traffic distribution combination module selects a carrier aggregation combination according to a connection request of a terminal in the carrier aggregation combination selection module, changes a carrier aggregation combination of already connected terminals, If the average load of at least one of the elementary carriers of the traffic channel exceeds a threshold value.

In addition, when the average load of at least one of the plurality of element carriers exceeds the threshold value, the traffic distribution module may extract a terminal to distribute traffic based on the selected carrier aggregation combination and traffic information for each terminal.

The present invention relates to a communication system in which a carrier aggregation technique is applied, in which a terminal requests a connection and is assigned a carrier aggregation combination, a carrier aggregation combination of an already connected terminal is changed, or at least one of a plurality of element carriers When the average load exceeds the threshold value, the traffic of the associated terminal is distributed in consideration of the average load of the element carriers so that the data transmission time is minimized or the load distribution between the element carriers is minimized. The load can be maintained evenly, and as a result, the speed of the user's sensory transmission can be improved.

1 is a view showing an embodiment of a mobile communication network using a carrier wave integration technique.
2 is a diagram showing a configuration of a communication system to which a carrier aggregation technique to which the present invention is applied.
3 is a block diagram showing the configuration of a load balancing apparatus to which the carrier aggregation technique according to the present invention is applied.
4 is a flowchart schematically showing the overall operation of a load balancing apparatus for a communication system to which the carrier aggregation technique according to the present invention is applied.
5 is a flowchart illustrating a load balancing method for a communication system to which the carrier aggregation technique according to the present invention is applied.
6 is a flowchart illustrating a traffic distribution process according to the first embodiment of the load balancing method according to the present invention.
7 is a flowchart illustrating a traffic distribution process according to the second embodiment of the load balancing method according to the present invention.
8 and 9 are views for explaining the effect of the load balancing method for a communication system to which the carrier aggregation technique according to the present invention is applied.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, detailed description of well-known functions or constructions that may obscure the subject matter of the present invention will be omitted. It should be noted that the same constituent elements are denoted by the same reference numerals as possible throughout the drawings.

The terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings and the inventor is not limited to the concept of terminology for describing his or her invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention, and not all of the technical ideas of the present invention are described. Therefore, It is to be understood that equivalents and modifications are possible.

Also, terms including ordinal numbers such as first, second, etc. are used to describe various elements, and are used only for the purpose of distinguishing one element from another, Not used. For example, without departing from the scope of the present invention, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component.

In addition, when referring to an element as being "connected" or "connected" to another element, it means that it can be connected or connected logically or physically. In other words, it is to be understood that although an element may be directly connected or connected to another element, there may be other elements in between, or indirectly connected or connected.

Also, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprising "or" having ", as used herein, are intended to specify the presence of stated features, integers, It should be understood that the foregoing does not preclude the presence or addition of other features, numbers, steps, operations, elements, parts, or combinations thereof.

In the following description, the frequency bands allocated between the BS and the MS are referred to as service bands. These service bands may be selected as a single band and assigned to the MS, and a plurality of service bands may be allocated to one band And may be allocated to the terminal. At this time, the frequency bands selected upon application of the carrier wave integration technique are referred to as component carriers (CC), respectively, and a plurality of element carriers selected to be aggregated are referred to as a carrier wave integration combination. For reference, the service band has a center frequency and a bandwidth set based on the center frequency.

The present invention implements load balancing between element carriers included in the carrier aggregation combination by distributing traffic of a terminal that is allocated a carrier aggregation combination based on a carrier aggregation technique through a base station.

In a communication system employing a carrier aggregation technique, when there are a plurality of element carriers and a load of some element carriers is relatively larger than that of the remaining element carriers, the element data carrier Should be minimized. For this, not only when selecting the carrier aggregation combination but also when the carrier aggregation combination is selected, the load condition of each element carrier must be considered when distributing the traffic for each element carrier of the selected carrier aggregation combination in the terminal. That is, based on the load information of each elementary carrier, the data transmission should be reduced on the elementary carrier having a large load, and the data transmission on the elementary carrier having a small load should be increased.

A load balancing apparatus and method for a communication system to which the proposed carrier convergence technology according to the present invention is applied based on this technical idea will be described with reference to FIG. 2 to FIG.

2 is a schematic view of a communication system to which the present invention is applied.

2, the communication system to which the present invention is applied includes a base station 10 for allocating radio resources and transmitting and receiving data through allocated radio resources, And terminals 20 for accessing the base station 10, allocating radio resources to be used for communication, and transmitting and receiving data through the allocated radio resources.

At this time, the base station 10 holds a plurality of service bands as radio resources, and transmits / receives data to / from the terminals 200 located in the coverage through the plurality of service bands. In the present embodiment, it is assumed that the base station 10 supports five service bands B1, B3, B5, B7_D, and B7_E. For reference, B1, B3, B5, B7_D, and B7_E are part of the service bands allocated to the mobile communication service providers and have a bandwidth of 10 MHz or 20 MHz, respectively. In addition to the carrier aggregation technique, the base station 10 may employ a high-order coding technique such as 64QAM / 256QAM or a multi-antenna technique such as MIMO (Multi-Input Muti-Output) in order to increase the transmission rate. However, when the communication coverage area capable of supporting the carrier aggregation technology is A1 for the base station 10, technologies such as the high-order coding technique such as the 64QAM / 256QAM or the MIMO technique are greatly influenced by the radio quality, The area where these techniques can be effectively used is only a part A2 of the entire communication coverage area A1.

The terminal 20 is a user apparatus having a mobile communication function used by a user and may be located in the communication coverage area A1 of the base station 10 according to the movement of the user, A1, the base station 10 requests a connection to the base station 10, performs connection through the service band allocated by the base station 10, and performs data communication. Such a terminal 20 can also support various technologies for increasing the transmission rate according to the terminal specifications, that is, at least one of a carrier aggregation technique and a high-dimensional coding technique such as 64QAM / 256QAM or MIMO or other communication technologies. However, since the present invention is related to carrier wave integration technology, it is assumed that the terminal 20 can support carrier wave integration technology for convenience of explanation.

Specifically, when requesting a connection to the base station apparatus 100 to perform carrier wave aggregation-based communication, the terminal 20 according to the present invention transmits at least two of a plurality of service bands provided by the base station apparatus 100 as elements Extracts at least one carrier aggregation combination that can be supported, and provides the base station 10 with information on the supportable carrier aggregation combination.

Here, one or more carrier aggregation combinations that can be supported may vary according to the specifications of the terminal 20. [ For example, when the terminal 20 is a terminal 21 capable of supporting 3CC (Component Carrier), it can support carrier combinations in which three or less service bands are selected and combined out of the five service bands shown in FIG. 2 When the terminal 20 is capable of supporting 5CC, the terminal 20 can support up to a carrier combination combining 4 and 5 element carriers in addition to the 3CC carrier combination. Here, the supportable carrier combinations can be further diversified depending on the multi-antenna technology in the terminal 20, for example, MIMO support.

The base station 10 selects the carrier aggregation combination to be allocated to the corresponding terminal 20 among the supportable carrier aggregation combinations upon receiving the carrier aggregation combinations that can be supported together with the connection request from the terminal 20, Aggregates the service bands corresponding to the included elementary carriers into one service band, connects to the terminal 20, and transmits / receives data to / from the terminal 20 simultaneously using the connected service bands.

3 is a block diagram showing the configuration of a load balancing apparatus according to the present invention applied to the communication system described above. The load balancing apparatus 100 shown in Fig. 3 may be provided in the communication system of Fig. 2 in the base station 10 and / or the terminal 20 or may be provided in the terminal 20 and / It can be implemented as an independent device.

3, the load balancing apparatus 100 according to the present invention includes a carrier combination selecting module 110 for selecting a carrier wave integration combination to be used for communication with the terminal 20 connected to the communication system as shown in FIG. 2, An information collection module 120 for collecting information necessary for selecting a carrier aggregation combination and traffic distribution such as average load and load distribution information for a plurality of element carriers used in a communication system to which the carrier aggregation technology is applied, Which distributes traffic for each element carrier included in the selected carrier aggregation combination so that the transmission time of the terminal 20 is minimized or the load distribution between element carriers is minimized by using the average load per element carrier, And a scheduling module for scheduling traffic transmissions of the terminal (20) based on a traffic distribution value of the traffic distribution module (130) It comprises 140.

For reference, the carrier aggregation combination selection module 110, the information collection module 120, the traffic distribution module 130, and the scheduling module 140 may be implemented by software or hardware or a combination of software and hardware For example, by loading and executing a program module recorded in a memory. In this case, the carrier aggregation combination selection module 110, the information collection module 120, the traffic distribution module 130, and the scheduling module 140 may refer to the program module, And may be a processor that loads and executes.

The operation of the load balancing apparatus 100 constructed as shown in FIG. 3 will be described with reference to the flowcharts of FIGS.

The load balancing apparatus 100 according to the present invention collects information necessary for load balancing, more specifically, selection of a carrier aggregation combination, and traffic distribution periodically through the information collection module 120 (S110). The information collected by the information collection module 120 may include, for example, the number of users per element carrier and the band information per element carrier available in the communication system to which the carrier aggregation technology is applied, and in another example , And average load information for each element carrier. In one embodiment, the average load information for each element carrier may be calculated based on the number of users connected to the corresponding element carrier and the band for each element carrier.

In addition, the load balancing apparatus 100 selects a radio resource to be used for communication, that is, a carrier aggregation combination, through interworking of the base station 10 and the terminal 20 (S120). The selection of the carrier aggregation combination is performed when the terminal 20 first transmits the information on the carrier aggregation combination usable in the base station 10 to the base station 10, And the carrier aggregation combination to be used by the terminal 20 is selected.

The traffic distribution module 130 of the load balancing apparatus 100 distributes the total traffic amount to the selected terminal 20 by the carrier waves included in the selected carrier aggregation combination by the carrier aggregation combination ). At this time, the load balancing apparatus 100 can perform traffic distribution based on the average load of each element carrier confirmed through the information collection module 120 and the total traffic amount of the terminal 20.

Thereafter, the scheduling module 140 of the load balancing apparatus 100 schedules data transmission by element carriers based on the distributed traffic amount (S140). Here, the scheduling may be performed according to various known scheduling algorithms, but it is not related to the load balancing according to the present invention, and a description thereof will be omitted.

The load balancing according to the present invention can be implemented through the traffic distribution process in step S130.

A load balancing process for a communication system to which the carrier aggregation technique according to the present invention is applied will be described with reference to FIG.

The present invention is proposed to equalize the load on each element carrier in a communication environment to which the carrier aggregation technique is applied. Unlike the prior art, unlike the conventional case, after the carrier aggregation combination is selected in step S120, We consider the distribution of traffic for each element carrier considering the average load information for each element of the aggregation combination.

In general, the load per element carrier is proportional to the number (number of users) of the connected terminals 20 to which the corresponding element carrier is allocated, as compared with the bandwidth of each element carrier. When the new terminal 20 is connected or when the carrier combination among the connected terminals 20 is changed, the load of the corresponding element carrier is changed.

The traffic distribution module 130 of the load balancing apparatus 100 according to the present invention firstly determines whether or not the connection of the terminal 20 It is checked whether a new carrier aggregation is selected by the request (S210). Here, the terminal 20 is a terminal newly connected to the communication system to which the carrier wave integration technology is applied, which means a transition from the RRC idle state to the RRC connected state.

Also, the traffic distribution module 130 according to the present invention checks in step S210 whether the carrier aggregation combination of the terminal 20 that has already been connected is changed (S220).

If the selection of the carrier aggregation combination is newly selected by the connection request of the terminal 20 in step S210 or the carrier aggregation combination allocated to the terminal 20 is changed in step S220, The average load is calculated for each element carrier based on the carrier aggregation combination (S230).

The traffic distribution module 130 of the load balancing apparatus 100 according to the present invention may be configured such that when the terminal 20 is requested to connect and the carrier aggregation combination is allocated or the carrier aggregation combination that has been previously allocated is not changed, (S240). Then, the average load information is compared with a preset threshold value to check whether there is an elementary carrier whose average load exceeds a threshold value (S250). Steps S240 through S260 may be performed separately from steps S210 and S220.

In step S250, if there is an elementary carrier whose average load exceeds a threshold value, the terminal 20 to which the traffic is redistributed among the terminals connected to the elementary carrier whose average load exceeds the threshold value is selected (S260) . At this time, the terminal 20 can be selected based on the carrier aggregation combination and the traffic information. For example, of the terminals connected to the element carrier having the average load exceeding the threshold value, the terminal having the largest traffic based on the amount of traffic remaining in the buffer can be selected.

After step S230 or S260, an expected load for each element carrier is calculated based on an average load of each element carrier and a traffic amount of the corresponding terminal (S270). Then, an elementary carrier (S280). At this time, the traffic distribution can distribute the traffic based on the minimization of the load distribution according to the expected element carriers, or distribute the traffic based on the minimization of the estimated transmission time, which can be performed as shown in FIG. 6 and FIG.

Before describing the traffic distribution process with reference to FIGS. 6 and 7, it is assumed that the order of the carrier aggregation combination of the terminal to distribute traffic is N, and the total traffic amount of the terminal 20 is t _tot . In addition, for convenience of explanation of the traffic distribution process, the average load of the nth element carrier among the 'N' element carriers is defined as an average RB (resource block) usage rate of the corresponding element carrier, and is specified as E [L _n ] . Here, the average load amount of the element carriers can be set by a method other than the average RB (Resource Block) usage rate. Also, the number of RBs of the n-th element carrier wave is _denoted by RB _n . The amount of traffic to be distributed to the n-th element carrier according to the present invention is denoted by t _n . Hereinafter, it is assumed that N = 3, n? [1,3,7] of the terminal 20 for convenience of explanation.

First, with reference to FIG. 6, a traffic distribution process according to the first embodiment of the present invention will be described. In the first embodiment, the present invention performs traffic distribution with priority to minimize load distribution between elementary carriers.

로 표현할 수 있다. 또한, 트래픽 분배 대상 단말의 n번째 요소 반송파에 배분될 트래픽 량을

이라 할 때, 상기 트래픽 분배 대상 단말이 n번째 요소 반송파에

만큼의 트래픽을 분배하였을 경우의 예상 부하량은

로 계산할 수 있다.To this end, the traffic distribution module 130 of the load balancing apparatus 100 according to the present invention predicts the expected load amount per element carrier based on the average load of each element carrier and the carrier aggregation combination of the terminal 20 ( S310). For example, the current loading of the nth element carrier is the product of the number of RBs of the nth element carrier and the average RB usage rate

. Also, the amount of traffic to be distributed to the nth element carrier of the traffic distribution target terminal

, The traffic distribution target terminal transmits to the n-th element carrier

The estimated load amount when the traffic is distributed is

.

는 다음의 수학식 1과 같이 계산될 수 있다.Subsequently, a traffic allocation value for each element carrier is calculated so that the variance of the estimated load for each calculated element carrier is minimized (S320). The traffic allocation value for each element carrier of n ∈ [1,3,7]

Can be calculated by the following equation (1).

The traffic amount of the corresponding terminal 20 is distributed based on the calculated traffic distribution value for each element carrier at step S330.

In this case, the data transfer rate can be improved by keeping the load of the element carriers equal.

Next, a traffic distribution algorithm according to the second embodiment of the present invention will be described with reference to FIG. In the second embodiment, traffic distribution according to the present invention takes precedence to minimizing the transmission time of the terminal 20. [

을 가장 빠르게 전송하기 위해서는 각 요소 반송파 별 트래픽 량 을 어떻게 설정해야 하는 지 계산한 결과를 바탕으로 동작한다. Referring to FIG. 6, a load balancing method according to the present invention includes:

In order to transmit the fastest traffic, Based on the result of the calculation of how to set.

In other words, since it is predicted that a small RB is allocated to the elementary carrier having a high load, it is predicted that a small amount of traffic will be allocated to the elementary carrier and conversely, a large number of RBs will be allocated to the elementary carrier having a low load. to be.

For this, the traffic distribution module 130 of the load balancing apparatus 100 according to the present invention allocates the traffic allocation capable of minimizing the transmission time, based on the estimated load for each element carrier and the carrier aggregation combination of the corresponding terminal 20 (S410). The traffic allocation value that can minimize the traffic transmission time of the terminal 20 can be calculated as shown in Equation (2).

Here, the above-mentioned? Is a constant value satisfying the following expression (3).

Equation (2) is a formula obtained by substituting 1 / E [L _n ] for the channel value in the water-filling technique.

Thereafter, traffic is distributed according to the traffic distribution value calculated in Equation (2) for each element carrier (S420).

The load balancing effect in the communication system to which the carrier aggregation technique according to the present invention is applied will be described with reference to the examples of FIG. 8 and FIG.

FIG. 8 is a diagram illustrating a situation in which a 3CC terminal UE1 and a 1CC terminal UE2, which is a non-CA, transmit simultaneously. Here, it is assumed that the total amount of traffic of the 3CC terminal UE1 and the 1CC terminal UE2 is the same, and the bandwidth of 3CC is 100RBs. In this case, according to the existing method, the traffic of the 3CC terminal UE1 is simply divided into 1/3 and distributed to the element carrier of each of the three bands. Here, since CC1 and CC2 among the element carriers are not connected to other terminals, transmission is completed only in 100 TTIs. However, since the 1CC terminal UE2 needs to share resources of 100RBs in the element carrier wave CC3, only 50RB is used in the CC3 of the 3CC terminal UE1, so that 200TTIs are generated to transmit all the traffic of the CC3. Therefore, the time taken for the 3CC terminal UE1 to transmit all the traffic is 200TTI. In addition, since the 1CC terminal UE2, which is a non-CA, shares resources with the 3CC terminal UE1 for the first 200TTIs, it can use only 50RB until the 3CC terminal UE1 finishes the transmission. Therefore, the total traffic transmission time of the 1CC terminal UE2 is 400 TTIs.

On the other hand, when the traffic distribution is performed according to the present invention, the 3CC terminal UE1 can control the traffic amount allocated to the CC3 using information that the load of the CC3 is higher than that of the CC1 and CC2. In this example, it is assumed that the 3CC terminal UE1 allocates the traffic so that only the two element carriers CC1 and CC2 are used, although the 3CC CA is possible. In this case, the 3CC terminal UE1 needs only 150 TTIs to transmit all of the total traffic through the element carrier CC1 and CC2 of the two bands. In other words, it can save 50 TTIs compared to existing methods. In addition, since the 1CC terminal UE2 does not need to share resources in the 3CC terminal UE1 and the CC3, the time to transmit all the traffic is also reduced to 300TTI.

Next, another example will be described with reference to Fig. In FIG. 9, it is assumed that the total amount of traffic of the 3CC terminal UE1 is three times that of the 1CC terminal UE2 in a situation where the 3CC terminal UE1 and the 1CC terminal UE2, which is a non-CA, simultaneously transmit.

In this case, according to the existing method, because the traffic is concentrated in the CC3 of the 3CC terminal UE1, the total traffic transmission time of the 3CC terminal UE1 is determined by CC3. That is, since the 3CC terminal UE1 and the 1CC terminal UE2 have the same traffic amount in the CC3, the total transmission time of the two terminals equals 200 TTIs.

However, according to the present invention, not all of the element carriers of the 3CC terminal UE1 allocate the traffic to the CC3, which is expected to drive traffic, so that both UEs can complete the transmission in a shorter time than before. That is, the 3CC terminal UE1 can complete the transmission in 150 TTIs, and the 1CC terminal UE2 can complete the traffic transmission within 100 TTIs.

The present invention is applied to a communication system based on a carrier wave integration technology, and is a system in which a terminal requests a connection and is assigned a carrier aggregation combination, a carrier aggregation combination of a terminal is changed, When one or more average load exceeds the threshold value, the traffic of the related terminal is distributed in order to minimize the data transmission time or to minimize the load distribution between the element carriers in consideration of the average load of the element carriers. The load between the elementary carriers used can be maintained evenly, and as a result, the speed of transmission of the user's senses can be improved.

10: Base station
20: terminal
100: load balancing device
110: Carrier aggregation combination selection module
120: Information gathering module
130: Traffic distribution module
140: Scheduling module

Claims (10)

Collecting average load information for each of a plurality of element carriers used in a communication system to which a carrier aggregation technique is applied; And
And an element included in the carrier aggregation combination for minimizing the traffic transmission time of the terminal or minimizing the load dispersion between the element carriers using the average load for each element carrier for the terminal allocated to the carrier aggregation combination connected to the communication system, Distributing traffic dynamically for each carrier wave;
And a load balancing method for a communication system to which a carrier aggregation technique is applied. The method according to claim 1,
And scheduling traffic transmissions of the mobile station based on the distribution result of the traffic. The method according to claim 1,
Further comprising the step of confirming whether allocation of the carrier aggregation combination is performed by a connection request of the terminal before the step of distributing the traffic,
Wherein the distributing the traffic causes the terminal that has been allocated a carrier aggregation combination to perform the traffic distribution according to the connection request. The method according to claim 1,
Further comprising the step of confirming whether the carrier aggregation combination of the already-connected terminal is changed before the step of distributing the traffic,
Wherein the distributing the traffic causes the terminal having the changed carrier aggregation combination to perform the traffic distribution. ≪ RTI ID = 0.0 > [10] < / RTI > The method according to claim 1,
Prior to distributing the traffic, periodically checking an average load per element carrier used in the communication system;
Confirming whether the average load per element carrier exceeds a predetermined threshold; And
Further comprising the step of extracting a terminal to perform the traffic distribution according to a carrier aggregation combination and a traffic amount of the terminal if at least one element carrier having an average load of the element carriers used in the communication system exceeds the threshold value,
Wherein the distributing the traffic causes the extracted terminal to perform the traffic distribution. ≪ RTI ID = 0.0 > [10] < / RTI > The method of claim 1, wherein distributing the traffic comprises:
Estimating an expected load amount per element carrier based on an average load per element carrier and a carrier aggregation combination of the terminal;
Calculating a traffic allocation value for each of the element carriers that minimizes the variance of the predicted load amount per element carrier;
And distributing the traffic of the terminal according to the calculated traffic allocation value for each element carrier. The method of claim 1, The method of claim 1, wherein distributing the traffic comprises:
Calculating a traffic allocation value for each element carrier to minimize a transmission time of the terminal based on an expected load per element carrier and a carrier combination of the terminal; And
And distributing the traffic of the terminal according to the calculated traffic allocation value for each element carrier. The method of claim 1, An information collection module for collecting the number of users and band information for each of a plurality of element carriers or the average load information for each of a plurality of element carriers used in the communication system to which the carrier aggregation technology is applied;
A carrier aggregation combination selection module for selecting a carrier aggregation combination for terminals connected to the communication system;
A traffic distribution module for distributing traffic for each element carrier included in the selected carrier aggregation combination so that the transmission time of the terminal is minimized or the load distribution between element carriers is minimized by using an average load for each element carrier;
And a scheduling module for scheduling a traffic transmission of the MS based on the traffic distribution value. The load balancing device for a communication system to which a carrier aggregation technique is applied. 9. The system of claim 8, wherein the traffic distribution module
In the carrier aggregation combination selection module, when the carrier aggregation combination is selected by the terminal connection request, the carrier aggregation combination of the terminals connected in advance is changed, or when the average load of at least one of the plurality of carrier carriers exceeds the threshold value And distributes the traffic to the load balancing device for the communication system to which the carrier aggregation technology is applied. 9. The system of claim 8, wherein the traffic distribution module
Wherein when a mean load of at least one of the plurality of elementary carriers exceeds a threshold value, the terminal extracts a terminal to distribute traffic based on the selected carrier aggregation combination and traffic information for each terminal. Load balancing device for the system.

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