KR101587035B1 - Apparatus and method for scheduling and resource allocation - Google Patents

Abstract

The present invention relates to a scheduling and resource allocation apparatus and a method thereof. A scheduling and resource allocation apparatus according to an embodiment of the present invention is a scheduling and resource allocation apparatus for selecting a user and allocating resource blocks using scheduling and resource allocation, A packet checking unit for checking whether the packet is longer than the length of the packet; And a packet acknowledgment unit for approving a current allocation result of the packet when the difference between the capacity of the resource allocated to the packet and the packet length is within a predetermined value when the capacity of the resource allocated to the packet is equal to or greater than the length of the packet . According to the present invention, in the packet scheduling and the resource allocation process, the length of the packet does not exceed the capacity of the allocated resource, and the capacity of the allocated resource does not excessively exceed the packet length, And the throughput of the MAC layer can be improved.

LTE, OFDM, scheduling, resource allocation, packet length, resource capacity

Description

[0001] Apparatus and method for scheduling and resource allocation [0002]

An embodiment of the present invention relates to a scheduling and resource allocation apparatus and a method thereof. More specifically, in the packet scheduling and resource allocation process, the length of the packet does not exceed the capacity of the allocated resource, and the capacity of the allocated resource does not excessively exceed the packet length, And a scheduling and resource allocation apparatus capable of improving the throughput of the MAC layer, and a method thereof.

Mobile communication is divided into first generation mobile communication, second generation mobile communication, third generation mobile communication, and the like depending on how much the transmission speed is improved. The generation division is divided into the international telecommunication It is hosted by the International Telecommunication Union (ITU).

Looking at the characteristics of each generation, first-generation mobile communication is called analog mobile communication, and it is characterized by voice communication only. That is, the speed of the first generation mobile communication is 10 kbps, data transmission is impossible, and the frequency used is 200 to 900 MHz. The first generation uses analog to speak of this communication because the frequency modulation (FM) method used to transmit voice is analog. The analog method has a disadvantage in that there is confusion in the call and the frequency can not be efficiently managed.

On the other hand, the second generation mobile communication uses a digital method and is capable of transmitting data such as a text message and an e-mail in addition to a voice call. At this time, the second generation mobile communication is diversified into a European GSM (Global System for Mobile communications) and a North American CDMA (Code Division Multiple Access).

GSM is a mobile communication system based on time division multiple access (TDMA) and asynchronous transmission network technology in which each frequency channel is divided into time, and is connected to an Integrated Services Digital Network (ISDN) A facsimile, a computer, and the like, and receive the mobile data service without using the mobile communication terminal. At this time, the transmission frequency of the base station is 935 to 960 MHz, the reception frequency of the base station is 890 to 915 MHz, and the transmission / reception frequency interval is 45 MHz, which is incompatible with the conventional analog system.

CDMA is a type of multiple access method using spread-spectrum communication technology. Since users transmit and receive signals by sharing time and frequency, their capacity is more than 10 times, their call quality is better, and security is higher Feature. Here, the spread-spectrum communication refers to spreading a signal with a bandwidth much wider than a bandwidth of a signal to be transmitted. Since the power density of the CDMA signal is low, it is difficult to detect the presence or absence of the signal. Also, since the receiver must accurately know the code used in spreading the original signal to produce the original signal in the process of despreading the received signal, The confidentiality of the communication is ensured, and the external disturbing signal is spread in the opposite direction in the despreading process, so that the communication can not be interrupted.

Third generation mobile communication is a next generation mobile communication technology that evolved from existing CDMA and GSM, such as WCDMA (Wideband Code Division Multiple Access) and HSDPA (High Speed Downlink Packet Access) The transmission speed is fast. In particular, HSDPA can reach the maximum transmission speed of 14.4 Mbps at the maximum, and is 7 times faster than WCDMA, which has a full speed of 2 Mbps, so it is also called 3G mobile communication that evolved from WCDMA. Using HSDPA network, it is theoretically possible to download 3 ~ 4 MP3 files per second.

The 4th generation mobile communication is a mobile communication having a transmission speed of 1 Gbps during suspension and 100 Mbps during movement. Theoretically, a 1.4 GB video can be received in about 11 seconds in the mobile communication terminal. However, the frequency to be used by the fourth generation mobile communication has not yet been determined, and studies for standardization are underway.

WiBro (Wireless Broadband Internet) is a wireless Internet technology that enables high-speed Internet access on the move. It is also referred to as Mobile WiMAX, and serves as a stepping-stone to link 3G and 4G mobile communications. The WiBro feature allows users to use the Internet wirelessly while traveling at a speed of 60 to 100 km, and the transmission speed is up to 20 Mbps, which is faster than HSDPA. WiBro is currently undergoing "WiBro Phase II" evolution, and the transmission speed is expected to increase to 30 ~ 50 Mbps.

Long Term Evolution (LTE) is a standard technology for the 4th generation mobile communication in Europe after GSM and WCDMA, and is being standardized in the workgroup under 3GPP (3 ^rd Generation Partnership Project). LTE is the next technology to overcome the technological limitations of the existing third generation mobile communication system and meet the needs of users over the next 10 years or more. It is expected to improve coverage expansion and system capacity, reduce data transmission rate and delay, All of the ways to improve the quality of the services provided while reducing are considered, and are characterized by strong mobile Internet.

With this characteristic, LTE is attracting attention as a core technology for next generation wireless communication by most mobile communication network operators. In particular, there are many technologies in LTE that include link adaptation, multiple-input multiple-output, among which scheduler and resource allocation are treated as very important mechanisms. Scheduler and resource allocation are essential considerations in design to improve throughput, packet delay, delay jitter and fairness between users.

Packet scheduling is an important mechanism for providing Quality of Service (QoS) to various users at the Media Access Control (MAC) layer, which selects or decides packets that can be transmitted in the current frame. Therefore, it is necessary to design the scheduler well to achieve high data rate, high cell throughput and fairness among users.

While the scheduler supplies QoS at the MAC layer, resource allocation at the physical layer protocol (PHY) guarantees the performance of the PHY layer. In the LTE system, Orthogonal Frequency Division Multiplexing (OFDM) is adopted as a downlink transmission technique. Therefore, the resources of the PHY layer in LTE are composed of 12 subcarriers in the form of resource blocks (RBs) and have a bandwidth of 180 kHz.

OFDM is a technology entirely different from CDMA, WCDMA or HSDPA, and a key feature of the OFDM system is that the RB in OFDM is exclusively allocated among users. This means that if one RB is assigned to a user, it can not be used by other users at the same time. This feature is different from the CDMA technology, which can be shared between users at the same time.

In wireless communications, scheduling and resource allocation are becoming a central theme in research, and a variety of schedulers that aim at different goals are being studied. For example, the Round Robin Scheduler schedules users one by one to maximize fairness among users. The maximum C / I scheduling algorithm allocates resources to users with optimal radio channel conditions. In this way, system throughput is maximized and fairness finds a compromise. To find a better compromise between throughput and user fairness, so-called proportional fair scheduling has been proposed, which has been widely adopted in other systems since its adoption in CDMA IS-386 systems.

Meanwhile, various resource allocation schemes are designed to optimize the performance of the physical layer (PHY). Because OFDM is quite different from technology such as CDMA, a resource algorithm designed for CDMA can not be used for OFDM at all.

The major difference between OFDM and CDMA in terms of resources is that, as described above, resources that are used exclusively among users in OFDM are shared in CDMA. Although both systems are capable of serving multiple users at the same time, these features have different considerations for OFDM systems and CDMA systems, and the design methods are different. Since CDMA is a self-interference system, the consideration for resource allocation in CDMA is to minimize interference, but in OFDM it is not necessary to allocate resources in consideration of interference issues. However, in OFDM, how to allocate exclusive occupation resources should be considered. In particular, if the length of a packet is larger than the allocated resource, it may lead to a packet transmission failure, which is a main cause of deterioration of the MAC layer throughput of the LTE system.

In an embodiment of the present invention, the packet length and the resource allocation process do not exceed the capacity of the allocated resource, and the capacity of the allocated resource exceeds the packet length The present invention also provides a scheduling and resource allocation apparatus capable of preventing the failure of packet transmission and improving the throughput of the MAC layer by preventing the packet transmission from being exceeded.

According to an aspect of the present invention, there is provided a scheduling and resource allocation apparatus for selecting a mobile communication user using scheduling and resource allocation and allocating resource blocks, A packet checking unit for checking whether a capacity of a resource allocated to a packet to be carried is greater than or equal to a length of a packet; And a packet acknowledgment unit for approving a current allocation result of the packet when the difference between the capacity of the resource allocated to the packet and the packet length is within a predetermined value when the capacity of the resource allocated to the packet is equal to or greater than the length of the packet .

Here, the scheduling and resource allocation apparatus may further include a resource release unit that releases resources of the packet when the length of the packet exceeds the capacity of the resource allocated to the packet.

In this case, the scheduling and resource allocation apparatus preferably further includes a resource reallocation unit for reallocating resources of released packets among other packets.

The scheduling and resource allocating apparatus may further include an excess resource releasing unit for releasing redundant resources of the packet when the difference between the capacity of the resource allocated to the packet and the packet length is larger than a predetermined value.

In this case, it is preferable that the scheduling and resource allocation apparatus further includes an excess resource reallocation unit for reallocating surplus resources of the released packet among candidate packets.

According to another aspect of the present invention, there is provided a method for scheduling and allocating resources in a downlink transmission, the method comprising the steps of: Checking whether the length is greater than or equal to the length; And approving the current assignment result for the packet when the difference between the capacity of the resource allocated to the packet and the length of the packet is within a predetermined value when the capacity of the resource allocated to the packet is equal to or greater than the length of the packet .

Here, the scheduling and resource allocation method may further include a step of releasing resources of the packet when the length of the packet exceeds the capacity of the resource allocated to the packet.

The scheduling and resource allocation method may further comprise reallocating resources of the released packet among other packets.

The scheduling and resource allocation method may further include a step of releasing surplus resources of the packet when the difference between the capacity of the resource allocated to the packet and the packet length is larger than a predetermined value.

In addition, the scheduling and resource allocation method may further comprise reallocating surplus resources of the released packets among the candidate packets.

In addition, the scheduling and resource allocation method includes: selecting a packet for transmission in a MAC (Media Access Control) layer; Supplying selected packets into the PHY layer to perform procedures including channel coding, modulation; And allocating arbitrary resources to the processed packets including channel coding, modulation, and the like.

In this case, the scheduling and resource allocation method includes: setting an index of a packet to which an arbitrary resource is allocated to 1; And if the current allocation result for the packet is granted, increasing the index by one.

If the number of the increased indexes is less than the number of remaining candidate packets, one of the candidate packets is selected, and the capacity of the resource allocated to the selected candidate packet is greater than or equal to the length of the selected candidate packet. It is preferable to approve the current allocation result for the candidate packet selected when the difference between the capacity of the allocated resource and the length of the selected candidate packet is within a predetermined value.

As described above, according to an exemplary embodiment of the present invention, the packet loss rate can be reduced by taking into consideration the potential influence of packet length on resources, and an attempt is made to match a packet length with a resource for transmitting a packet The MAC packet data rate can be improved and the spectral efficiency can be increased.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals whenever possible, even if they are shown in different drawings. In the following description of the present invention, 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.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

1 is a diagram illustrating packet scheduling and a resource allocation process. Referring to the drawing, the scheduler selects a set of packets for transmission in the MAC layer. The selected packets are supplied into the PHY layer to undergo procedures such as channel coding, modulation and the like, and finally, the resource allocation unit allocates arbitrary resources to the packets.

At this time, if the capacity of the resource blocks allocated by the resource allocation unit exceeds the packet length in the packet scheduling and resource allocation process, the packet transmission may be failed and the throughput of the MAC layer may be lowered. 2, a scheduling and resource allocation apparatus 200 according to an embodiment of the present invention includes a packet checking unit 210, a packet acknowledging unit 220, a resource releasing unit 230, A resource reassigning unit 240, an excess resource releasing unit 250, and an excess resource reassigning unit 260. [

The packet checking unit 210 checks whether the capacity of the resource allocated to the packet to be transmitted or returned is equal to or greater than the length of the packet.

As described above, in the PHY layer of the LTE, the resource is composed of 12 subcarriers in the form of a resource block (RB) and has a bandwidth of 180 kHz. Also, resource blocks are exclusively allocated among users. Also, in an LTE system, different users may have different packets.

Importantly, the role of the resource block is to transmit or carry the packet. Since the different packets may have different lengths and the resource block is exclusively allocated among users, the number of resource blocks may vary depending on the packet. Therefore, the capacity, i.e., the transmission rate for the packets, may be different from each other.

Here, a resource block allocated to a specific packet must have a capacity sufficient to carry the packet. However, it is preferable that the transmission capacity of the resource block allocated so as not to be wasteful does not exceed the packet length too much.

Assuming that a resource in a resource block is a container that can hold a certain amount of water and that the packet contains water in the resource block, the different packets will correspond to different amounts of water, It becomes clear.

First, the volume of water must not exceed the volume of the container to successfully transfer packets. That is, the length of the packet should be equal to or less than the capacity of the allocated resource block. If this point is not taken into consideration, a packet transmission failure occurs.

Second, containers should contain as much water as they can efficiently use. This means that the difference between the length of the packet and the capacity of the allocated resource blocks should be kept as low as possible. If this point is not taken into consideration, the utilization of the resource block results in low efficiency, that is, resource allocation with low efficiency.

Due to this fact, the packet checking unit 210 selects at least one of the packets to be transmitted or carried, and checks whether the capacity of the resource allocated to the selected packet or the capacity of the resource block is greater than or equal to the length of the selected packet. At this time, the packet checking unit 210 preferably sets the index to 1 for the packets to which an arbitrary resource is allocated.

If the difference between the capacity of the resource allocated to the selected packet and the length of the selected packet is within a predetermined value, if the capacity of the resource allocated to the selected packet is greater than or equal to the length of the selected packet, Accept the resource allocation result. If the current resource allocation result for the selected packet is approved, the packet checking unit 210 preferably increases the index by one.

At this time, if the number of increased indexes is less than the number of candidate packets remaining to be transmitted or returned, the packet checking unit 210 selects at least one of the candidate packets and determines the capacity of the resource allocated to the selected candidate packet Or more.

If the difference between the capacity of the resource allocated to the selected candidate packet and the length of the selected candidate packet is within a predetermined value when the capacity of the resource allocated to the selected candidate packet is greater than or equal to the length of the selected candidate packet, It is desirable to approve the current assignment result for the selected candidate packet.

If the length of the selected packet exceeds the capacity of the resource allocated to the selected packet, the resource releasing unit 230 releases the resource or resource block allocated to the selected packet. At this time, the resource reassigning unit 240 reallocates resources released by the resource releasing unit 230 among other packets.

If the difference between the capacity of the resource allocated to the selected packet and the length of the selected packet is larger than the predetermined value, the surplus resource releasing unit 250 releases the surplus resource among the resources allocated to the selected packet. At this time, the surplus resource reassigning unit 260 reallocates among the remaining remaining candidate packets for transmitting or returning the resources released by the surplus resource releasing unit 250. Here, the surplus resource may be a resource of the second half exceeding the length of the selected packet, or may be a resource of the first half of the length exceeding the length of the selected packet. However, the portion of the surplus resource for releasing is not limited to that described, and various portions may be selected as surplus resources according to the designer's choice.

3 is a flowchart showing an embodiment of a scheduling and resource allocation method by the scheduling and resource allocation apparatus of FIG.

As shown in FIG. 1, the scheduler selects a set of packets to be transmitted in the MAC layer, and the selected packets are supplied into the PHY layer and undergo procedures such as channel coding, modulation, and the like. The resource allocation unit allocates arbitrary resources to packets that have undergone channel coding, modulation, and the like (S301). At this time, if any resources are allocated to the packets, the packet checking unit 210 preferably sets the index i for the packets to 1 (S303).

The packet checking unit 210 selects at least one of the packets to be transmitted or carried and checks whether the capacity of the resource allocated to the selected packet or the capacity Ci of the resource block is equal to or greater than the length Li of the selected packet (S305). At this time, the packet inspecting unit 210 can sequentially select a packet for a packet to be transmitted or transmitted, and can randomly select the packet. Through such a process, it is ensured that the capacity of the resource allocated to the packet is sufficiently larger than the length of the packet.

If the capacity Ci of the resource allocated to the selected packet is equal to or greater than the length Li of the selected packet, and the difference between the capacity Ci of the resource allocated to the selected packet and the length Li of the selected packet is within the predetermined value? (Step S309). ≪ tb > < TABLE > This process ensures that the capacity of the resource allocated to the packet is not excessively exceeded.

Here, the variable < [Delta] > representing a predetermined value serves as a limiter for applying the difference between the packet length Li and the allocated capacity Ci. Setting the variable δ too small means that the restrictions are applied very strictly, which means that the capacity of the resource is almost fully utilized and there is little wasted capacity. By adjusting this variable 隆, the throughput of the MAC layer can be minimized. If the variable δ is too large, the constraints are loose and the conditions are easily satisfied. In this case, the throughput of the MAC layer is not so high, but the fairness of compromise between users is increased.

If the current resource allocation result for the selected packet is approved, the packet checking unit 210 preferably increases the index by one (S311).

At this time, if the number of increased indexes is less than the number of candidate packets remaining to be transmitted or returned (S313), the packet checking unit 210 selects at least one of the candidate packets, It is desirable to check whether the packet length is longer than the length of the packet (S305). If the number of increased indices is greater than the number of candidate packets remaining to be transmitted or returned, the scheduling and resource allocation method of the LTE system according to an embodiment of the present invention ends.

If the capacity of the resource allocated to the selected candidate packet is greater than or equal to the length of the selected candidate packet, the packet acknowledgment unit 220 determines the capacity of the resource allocated to the selected candidate packet and the length of the selected candidate packet as in steps S307 and S309. It is preferable to approve the current allocation result for the selected candidate packet when the difference is within the predetermined value. At this time, it is preferable that the index is increased by 1 again as in step S311.

If the length of the selected packet or the length of the selected candidate packet exceeds the capacity of the selected packet or the resource allocated to the selected candidate packet (S305), the resource releasing unit 230 deletes the selected packet or the resource The block is released (S315). At this time, the index is incremented by 1, and the resource reassigning unit 240 preferably reassigns resources released by the resource releasing unit 230 among other packets.

When the difference between the capacity of the resource allocated to the selected packet or the selected candidate packet and the length of the selected packet or the selected candidate packet is larger than the predetermined value (S307), the surplus resource releasing unit 250 allocates the selected packet or the selected candidate packet The surplus resource is released (S317). At this time, it is preferable that the surplus resource reassigning unit 260 reassigns among the remaining remaining candidate packets to transmit or return the resources released by the surplus resource releasing unit 250. [

As described above, the scheduling and resource allocation apparatus, and the scheduling and resource allocation method thereof according to an embodiment of the present invention can reduce the loss rate of packets by considering the potential impact of packet length on resources .

In addition, by trying to match the length of the packet with the resource that transmits the packet, the MAC packet data rate can be improved and the spectral efficiency can be increased.

Also, by adjusting the value of the variable delta, the compromise between system throughput and fairness can be controlled.

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. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program may be stored in a computer-readable storage medium, readable and executed by a computer, thereby implementing embodiments of the present invention. As the storage medium of the computer program, a magnetic recording medium, an optical recording medium, a carrier wave medium, or the like may be included.

Furthermore, the terms "comprises", "comprising", or "having" described above mean that a component can be implanted unless otherwise specifically stated, But should be construed as including other elements. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted to be consistent with the contextual meanings of the related art, and are not to be construed as ideal or overly formal, unless expressly defined to the contrary.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

As described above, the embodiment of the present invention is applied to the field of LTE system, and it is possible to reduce the packet loss rate by considering the potential influence of packet length on resources, It is a very useful invention that produces an effect of improving the MAC packet data rate and increasing the spectral efficiency.

1 is a diagram illustrating packet scheduling and a resource allocation process.

2 is a diagram schematically illustrating a scheduling and resource allocation apparatus according to an embodiment of the present invention.

3 is a flowchart showing an embodiment of a scheduling and resource allocation method by the scheduling and resource allocation apparatus of FIG.

Description of the Related Art

200: LTE system 210: Packet Inspection Unit

220: packet acknowledgment unit 230: resource release unit

240: resource reassignment unit 250: surplus resource releasing unit

260: Surplus resource reallocation

Claims (13)

A scheduling and resource allocation apparatus for allocating a resource block to a packet to be transmitted or carried, A packet checking unit for checking whether a capacity of a resource allocated to the packet is equal to or greater than a length of the packet; And When a difference between a capacity of a resource allocated to the packet and a length of the packet is less than a predetermined value when a capacity of a resource allocated to the packet is equal to or greater than a length of the packet, However, If the current allocation result of the packet is approved, increases the index of the resource allocated to the packet, and if the number of the packets set to the incremented index is equal to or less than the number of candidate packets remaining, And to permit the scheduling and resource allocation. The method according to claim 1, And for releasing resources of the packet when the length of the packet exceeds the capacity of the resource allocated to the packet, The scheduling and resource allocation apparatus further comprising: delete The method according to claim 1, When the difference between the capacity of the resource allocated to the packet and the length of the packet is larger than the predetermined value, The scheduling and resource allocation apparatus further comprising: delete A method for scheduling and allocating resources in downlink transmission, Checking whether a capacity of a resource allocated to a packet to be transmitted or carried is not less than the length of the packet; And If the difference between the capacity of the resource allocated to the packet and the length of the packet is less than a predetermined value, if the capacity of the resource allocated to the packet is greater than or equal to the length of the packet, Including, If the current allocation result of the packet is approved, increases the index of the resource allocated to the packet, and if the number of the packets set to the incremented index is equal to or less than the number of candidate packets remaining, And granting the grant to the scheduler. The method according to claim 6, If the length of the packet exceeds a capacity of a resource allocated to the packet, releasing a resource of the packet And allocating resources to the scheduling resource. delete The method according to claim 6, If the difference between the capacity of the resource allocated to the packet and the length of the packet is greater than the predetermined value, releasing the surplus resource of the packet And allocating resources to the scheduling resource. delete 10. A method according to any one of claims 6, 7 and 9, Selecting a packet for transmission in a Media Access Control (MAC) layer; Supplying the selected packet into the PHY layer to perform procedures including channel coding, modulation; And Allocating arbitrary resources to the packet through a procedure including channel coding and modulation And allocating resources to the scheduling resource. 12. The method of claim 11, Setting an index of the packet to which an arbitrary resource is allocated to 1; And Incrementing the index by one if the current allocation result for the packet is approved And allocating resources to the scheduling resource. 13. The method of claim 12, And selecting one of the candidate packets if the number of the indexes increased is equal to or less than the number of candidate packets remaining and allocating resources allocated to the selected candidate packet when the capacity of the resource allocated to the selected candidate packet is equal to or longer than the length of the selected candidate packet The current allocation result for the candidate packet selected when the difference between the capacity of the resource and the length of the selected candidate packet is within a predetermined value.

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