KR101405609B1 - Base station, method for allocating resource for device to device communication thereof and terminal performing device to device communication - Google Patents

Abstract

A resource allocation method for direct communication between a base station and an apparatus thereof and a terminal apparatus performing direct communication between apparatuses are disclosed. A base station for allocating frequency resources for direct communication between devices in a cell, the base station comprising: a setting unit configured to set a first radius range centered on a terminal device to perform direct communication between devices and a second radius range centered on the base station, part; And an allocation unit that allocates frequency resources of the cellular terminal apparatus located in the second radius range excluding the first radius range among the activated cellular terminal apparatuses in the cell to the terminal apparatuses performing the inter-apparatus direct communication . According to the present invention, there is an advantage that QoS of activated terminal devices can be guaranteed and frequency efficiency can be increased. In addition, according to the present invention, it is possible to effectively schedule a cellular terminal device capable of sharing resources, thereby obtaining an additional multi-user diversity gain and thereby maximizing the system yield. Also, according to the present invention, there is an advantage that the channel feedback load to the base station can be effectively reduced.

Description

TECHNICAL FIELD [0001] The present invention relates to a base station, a resource allocation method for direct communication between the base station and the base station, and a terminal device performing direct communication between the base station and the base station.

Embodiments of the present invention relate to a resource allocation method for direct communication between a base station and an apparatus and a terminal apparatus for performing direct communication between apparatuses. More particularly, the present invention relates to a method and apparatus for guaranteeing QoS of activated terminal apparatuses, A method of allocating resources for direct communication between a base station and an apparatus therefor, and a terminal apparatus performing direct communication between apparatuses.

D2D (Device-to-Device) communication (direct communication between devices) means a technology in which two terminal devices located at a close distance communicate directly without going through a base station.

D2D communication is attracting attention as a next generation wireless communication technology due to advantages such as an increase in system yield, a decrease in transmission power of a terminal device, and a reduction in load of a base station. As a prior art related to D2D communication, Korean Patent Laid-Open No. 10-2009-0005676 is available.

In order to efficiently utilize radio frequency resources, such D2D communication is allocated from a base station in the same frequency band as that of a cellular user.

Therefore, interference occurs between the cellular user sharing the same frequency resource and the D2D user, and thus an effective resource allocation technique for solving the interference problem is required.

In order to solve the problems of the related art as described above, the present invention guarantees the QoS of activated terminal devices and simultaneously performs a resource allocation method for directly communicating with the base station and a direct communication between devices, which can increase the frequency efficiency And a terminal device.

Other objects of the invention will be apparent to those skilled in the art from the following examples.

According to an aspect of the present invention, there is provided a base station for allocating frequency resources for direct communication between devices in a cell, the base station including: a first radius range centering on a terminal device to perform direct communication between devices; A setting unit for setting a second radius range around the base station; And an allocation unit for allocating a frequency resource of the cellular terminal device located in the second radius range excluding the first radius range among the activated cellular terminal devices in the cell to the terminal device performing the inter-device direct communication A base station is provided.

Wherein the first radius range and the second radius range are determined based on the system yield when the terminal device performing the direct communication between the devices operates in the cellular mode and the cell yield when any one of the cellular terminal devices in the cell is shared with the cellular terminal device And can be set based on the system yield when operating in direct communication mode between apparatuses.

Wherein the first radius range and the second radius range are further based on a minimum SINR (Signal-to-Interference-Noise Ratio) quality of service (QoS) of a terminal device that is to perform direct communication between the apparatus and the one of the cellular terminal devices .

The first radius range is proportional to the distance between the terminals to perform the direct communication between the devices and may be inversely proportional to the distance between the terminal to perform the direct communication between the devices and the base station.

When the number of the cellular terminal devices located within the second radius range excluding the first radius range is two or more, the allocating section allocates the frequency resources of the cellular terminal devices that maximize the system yield among the two or more cellular terminal devices to the inter- Can be assigned as a resource for.

Wherein the allocating unit allocates the frequency resources different from the frequency resources of the activated cellular terminal apparatus in the cell to the inter-apparatus direct communication when the cellular terminal apparatus located in the second radius range excluding the first radius range does not exist Can be assigned to the terminal device to be used.

According to another aspect of the present invention, there is provided a method of allocating frequency resources for direct communication between devices in a cell, the method comprising: a first radius range centering on a terminal device to perform direct communication between devices; Setting a second radius range centered on the first radius; And allocating a frequency resource of the cellular terminal device located in the second radius range excluding the first radius range among the activated cellular terminal devices in the cell to the terminal device performing the inter-device direct communication An allocation method is provided.

According to another embodiment of the present invention, there is provided a terminal apparatus for performing direct communication between devices in a cell, the terminal apparatus being located outside a first radius range centering on the terminal apparatus among activated cellular terminal apparatuses in the cell, There is provided a terminal apparatus for performing direct communication between apparatuses by sharing frequency resources of a cellular terminal apparatus located within a second radius range as a center.

According to the present invention, there is an advantage that QoS of activated terminal devices can be guaranteed and frequency efficiency can be increased.

In addition, according to the present invention, it is possible to effectively schedule a cellular terminal device capable of sharing resources, thereby obtaining an additional multi-user diversity gain and thereby maximizing the system yield.

Also, according to the present invention, there is an advantage that the channel feedback load to the base station can be effectively reduced.

1 is a diagram schematically showing a radio communication state of a pair of D2D candidate terminal apparatuses in a cell.
2 is a diagram schematically illustrating a method for determining whether or not a D2D communication mode is operable according to an embodiment of the present invention.
3 is a diagram showing a detailed configuration of a base station according to an embodiment of the present invention.
4 is a flowchart illustrating a method of allocating resources for direct communication between apparatuses of a base station according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating a method of allocating resources of a base station according to an embodiment of the present invention, according to the flow of time, centering on the presence of a cellular terminal device in the DMPR.
6A is a diagram illustrating a simulation result of a resource allocation method for direct-to-device communication according to an embodiment of the present invention with respect to a D2D candidate terminal when there are ten activated cellular terminal devices in the cell.
6B is a diagram showing a comparison of system throughput performance by a resource allocation method for direct-to-machine communication according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram schematically showing a radio communication state of a pair of D2D candidate terminal apparatuses in a cell.

As shown in FIG. 1, a pair of D2D candidate terminal apparatuses (terminal apparatuses for performing direct communication between apparatuses, DT and DR) in a cell operate in one of two communication modes, i.e., a cellular mode or a D2D mode .

The cellular mode is a mode in which a base station is regarded as a repeater and communication is performed between the terminal devices. At this time, the terminal devices are allocated independent frequency resources and communicate.

The D2D mode is a mode in which the D2D transmitting / receiving terminal device directly communicates. In this case, the terminal device reuses the frequency resources of the existing activated cellular terminal device to communicate.

In the D2D mode for reusing frequency resources, the efficiency of the radio frequency resource is increased as compared with the cellular mode.

On the other hand, in order to operate the D2D candidate terminal apparatus in the D2D mode due to the characteristics of the D2D mode for reusing the frequency resources of the existing activated cellular terminal apparatus, the quality of service (QoS) of each terminal apparatus is satisfied Frequency efficiency (in terms of system yield) must be ensured.

Accordingly, the resource allocation method for direct communication between devices according to an embodiment of the present invention determines whether the D2D candidate terminal device can operate in the D2D communication mode based on the location information of the terminal devices in the cell.

That is, a resource allocation method capable of satisfying QoS (Quality of Service) of each terminal device based on location information of terminal devices in a cell and guaranteeing high frequency efficiency is presented.

According to the present invention, there is an advantage that channel feedback to the base station can be effectively reduced by utilizing the location information of the terminal devices for determining the D2D communication mode.

Further, it is possible to obtain an additional multi-user diversity gain by effectively scheduling a cellular terminal device capable of sharing resources, thereby maximizing the system yield.

For convenience of explanation, it is assumed that an uplink environment of a single cell based on a TDD (Time Division Duplex) OFMDA (Orthogonal Frequency Division Multiple Access) is assumed, and N _C cell terminal units (CUE) It is assumed that there is a D2D candidate terminal device (DT, DR). However, the present invention is not limited thereto.

2 is a diagram schematically illustrating a method for determining whether or not a D2D communication mode is operable according to an embodiment of the present invention.

2, whether the D2D candidate terminal apparatus can operate in the D2D communication mode can be determined from a first radius ( R _outer ) based on the D2D candidate terminal apparatus and a second radius ( R _inner ) based on the base station .

More specifically, when the activated cellular terminal device in the cell is located outside the first _outer radius ( R _outer ) from the D2D candidate terminal device and is located within the second radius ( R _inner ) from the base station, the D2D candidate terminal device performs D2D communication Mode, and resources of the corresponding cellular terminal device are allocated as resources for D2D communication.

That is, when there is at least one activated cellular terminal device in a cell located in a second radial range (DMPR, D2D-Mode-Possible Region) excluding the first radius range, the D2D candidate terminal device transmits the resource And can operate in the D2D communication mode.

At this time, if there are two or more activated cellular terminal devices located in the DMPR, the resources of the cellular terminal devices having the maximum system throughput can be allocated for the D2D communication through the scheduling process. This will be described in more detail below.

If none of the activated cellular terminal devices located in the DMPR exists, the D2D candidate terminal device operates in the cellular communication mode, and independent resources are allocated to the D2D candidate terminal device.

Hereinafter, with reference to FIG. 3 to FIG. 5, an operation of a BS (BS) according to an embodiment of the present invention to allocate resources for direct communication within an intra-cell device to a D2D candidate terminal apparatus will be described in more detail.

3 is a diagram showing a detailed configuration of a base station 100 according to an embodiment of the present invention.

4 is a flowchart illustrating a method of allocating resources for direct communication between devices of a base station 100 according to an embodiment of the present invention.

3 and 4, the base station 100 includes a setting unit 110 and an allocation unit 120. The resource allocation method includes a step S410 of setting and a step S420 of allocating do.

First, in step S410, the setting unit 110 sets a first radius range around the terminal apparatus (D2D candidate terminal apparatus, DT and DR) A second radius range is set.

The first radius range and the second radius range may share the system yield when the D2D candidate terminal apparatus operates in the cellular mode and the cellular terminal apparatuses activated in the cell, Can be set based on the system yield when operating in the communication mode (D2D mode).

In addition, the first radius range and the second radius range correspond to a minimum SINR (Signal-to-Interference-Noise Ratio) quality of service (QoS) of any one of the cellular terminal devices and the D2D candidate terminal devices, As shown in FIG.

A process of setting the first _outer radius ( R _outer ) range and the second _inner radius ( R _inner ) range for determining whether the setting unit 110 can operate in the D2D communication mode according to an embodiment of the present invention will be described in more detail. Respectively.

First, the system yield when the D2D candidate terminal apparatus operates in the cellular mode can be calculated according to the following equation.

Here, R ^CM denotes a system yield when the D2D candidate terminal apparatus operates in the cellular mode, N _C denotes the number of the cellular terminal apparatuses in the cell, SNR _Ck denotes a Signal-to-Noise Ratio (SNR) of the kth cellular terminal apparatus, SNR _D is the D2D candidate terminal device operating in a cellular mode, SNR, P _Ck is the transmit power, P _D of the k-th cellular terminal equipment transmit power, P _BS is the transmit power, d _CkB of the base station of the D2D transmitting terminal device k second distance between the cellular terminal and the base station, d _DB is a distance between the D2D transmission terminal apparatus and a base station, d _BD is the distance between the D2D reception terminal apparatus and a base station, α is the variance of the path loss constants, N ₀ is the Gaussian noise Respectively.

Next, the system yield when the D2D candidate terminal apparatus shares resources with the i < th > cellular terminal apparatus and operates in the D2D mode can be calculated according to the following equation.

Herein, SINR _Ci and SINR _D denote the SINR (Signal-to-Interference-Noise Ratio) of the i- th CELLULATOR and the D2D terminal sharing resources, respectively, d _DD denotes the distance between the transmitting terminal device and the receiving terminal device Respectively.

Meanwhile, the uplink transmission power of the D2D candidate terminal apparatus should be adjusted differently according to the communication mode.

When the D2D candidate terminal device operates in the cellular mode, the terminal devices activated in the cell are allotted orthogonal frequency resources, and there is no interference with each other. Therefore, the D2D candidate terminal device operates with the maximum transmission power ( P _max ) .

On the other hand, when the D2D candidate terminal apparatus operates in the D2D mode, it is necessary to adjust the transmission power to a value smaller than a specific interference level in consideration of the amount of interference to the cellular user.

For example, the D2D terminal apparatus operating in the D2D mode can operate with the transmission power as expressed by the following equation.

Where P _D is the uplink transmission power of the D2D terminal and ? Is the maximum allowable interference level, respectively.

Subsequently, the system yields in the respective communication modes are compared, and conditions such as the following equations can be set such that the D2D communication mode is judged to be possible when the system has high frequency efficiency.

Where κ is a normalization constant and can be defined as κ = ( N _C +1) / N _C. The normalization constant is caused by the fact that the number of frequency resources used when the D2D candidate terminal apparatus operates in the cellular mode differs from the number of frequency resources used when operating in the D2D mode.

That is, since when operating in the cellular mode, the frequency resources of N _C +1 is being used, the frequency resources of N _C as when operating in D2D Mode, in order to compare the yield of the system at each communication mode, the frequency used A normalization constant that reflects the resource is needed.

In the case where the QoS of each of the terminal equipments is ensured, it is possible to set the same condition as the following equation so that it is determined that the D2D communication mode is possible.

Here, γ _C and γ _D mean the minimum SINR for guaranteeing the QoS of a cellular user sharing a resource and a _{D 2 D} user.

From the above equations (1) and (2), a range that satisfies the condition of the above-mentioned equation (4) can be derived as the following equation.

In this case, the SNR can be approximated by assuming a high SNR so that it can be expressed in a closed form, and the amount of computation can be reduced within a relatively small error range as compared with the case where the approximation is not approximated.

Similarly, from the above equation (2), a range that satisfies the conditions of the equations (5) and (6) can be derived as the following equation.

The range satisfying all of the equations (7) to (9) can be summarized as the following mathematical expression.

As a result, Equation (10) and Equation (11) mean a range in which QoS can be satisfied and high frequency efficiency can be guaranteed. This means that the D2D candidate terminal apparatus can operate in the D2D mode do.

When according to the above Equation 10 and Equation 11, the cells in the active cellular terminal equipment located at a second radius (R _inner) range other than the range of the first radius (R _outer) (that is, when positioned in DMPR ), The D2D candidate terminal apparatus becomes operable in the D2D communication mode.

That is, if there is a cellular terminal apparatus activated in the DMPR for a given D2D candidate terminal apparatus, the D2D candidate terminal apparatus can communicate in the D2D mode, and if there is no activated cellular terminal in the DMPR, It must be operated in cellular mode.

More specifically, referring to Equations (7) to (11), the range of the first radius R _outer1 , R _outer2 is proportional to the distance d _DD between the D2D candidate terminal devices, Is inversely proportional to the distance ( d _DB )

That is, the first radius R _outer is determined by the ratio of d _DD and d _DB , and the first radius R _outer can be expressed by the following equation using an arbitrary constant K.

)이 클수록 D2D 링크의 SINR이 높아질 뿐만 아니라 이로 인해 주파수 효율 또한 증가하게 된다. Since the amount of interference that the cellular terminal gives to the D2D terminal is determined by the transmission power of the cellular terminal, the SNR of the D2D link

The larger the SINR of the D2D link is, the higher the frequency efficiency is.

In other words, the D2D terminal is far from the base station, or (d _DB is equal to or) D2D The distance is close end-to-end (d _DD is less more) The above equation (4) or to rise the probability to satisfy the following equation 6 D2D communication Mode is preferred.

Equation (12) represents the minimum d _CiD satisfying Equations (4) and (6), and resources of the cellular terminals existing in a region where d _CiD is larger than the region expressed by Equation (12) It can be reused for.

At this time, K may be calculated by reflecting the instantaneous R ^CM , but may be predefined and used as a specific value at the base station.

_Next , the second _inner radius ( R _inner ) range is determined from the selected system parameters, and the transmission SNR ( P _max / N ₀ ), the maximum interference level ( ? ), , And d _CiB for ensuring the minimum QoS of the cellular user due to frequency reuse is determined from the value of the minimum SINR ( ? _C ) of the cellular user.

That is, the second radius ( d _CiB ) enabling the D2D mode is determined irrespective of the position of the D2D terminal, and it controls the transmission power of the D2D terminal operating in the D2D mode to assure the interference to the cellular terminal to a certain level .

Next, in operation S420 according to an embodiment of the present invention, the allocating unit 120 allocates the cellular terminal apparatus CUE located within the second radius range excluding the first radius range among the activated cellular terminal apparatuses CUE And allocates the frequency resource to a terminal device to perform direct communication between the devices.

Meanwhile, when there are two or more terminal apparatuses located in the DMPR among the activated cellular terminal apparatuses in the cell, a process of determining which cellular terminal apparatus resources to share with the D2D candidate terminal apparatus can be additionally performed.

According to an embodiment of the present invention, a process of selecting and scheduling a cellular terminal device that maximizes the system yield among activated cellular terminal devices located in the DMPR may be performed as follows. Then, additional diversity gain can be obtained through this process.

Here, D denotes a set of activated cellular terminal devices located in the DMPR, and i ^* denotes a cellular terminal device that maximizes the system yield.

FIG. 5 is a flowchart illustrating a method of allocating resources of a base station according to an embodiment of the present invention, according to the flow of time, centering on the presence of a cellular terminal device in the DMPR.

Referring to FIG. 5, first, a cellular terminal device and a D2D candidate terminal device to communicate are determined (S510). This can be performed according to the scheduling method in the existing wireless communication system.

Then, based on the location information of the D2D candidate terminal apparatus, the DMPR is determined through Equations 10 and 11 (S520), and it is determined whether the activated cellular terminal apparatus exists in the DMPR (S530) .

When there is no cellular user in the DMPR, the D2D candidate terminal apparatus operates in the cellular communication mode, and independent resources are allocated for this operation (S552 and S554).

When there is at least one cellular user in the DMPR, the resources of the cellular user having the maximum system throughput are allocated for D2D communication through scheduling, and at the same time, the transmission power of the D2D communication terminal apparatus is adjusted so as not to exceed the specific interference level To S546).

6A is a diagram illustrating a simulation result of a resource allocation method for direct-to-device communication according to an embodiment of the present invention with respect to a D2D candidate terminal when there are ten activated cellular terminal devices in the cell.

FIG. 6B is a diagram showing a comparison of system throughput performance by a resource allocation method for direct-to-machine communication according to an embodiment of the present invention.

As shown in FIG. 6A, the D2D candidate terminal apparatus can perform D2D communication using the frequency resources of the activated cellular terminal apparatus located in the second radius range excluding the first radius range, that is, within the DMPR.

As shown in FIG. 6B, the system to which the resource allocation method according to an embodiment of the present invention is applied includes a system (Random D2D) to which an arbitrary resource allocation method is applied, a system in which a D2D candidate terminal apparatus operates only in a cellular mode (no D2D) in terms of system yield.

Embodiments of the present invention may be implemented in the form of program instructions that can be executed on various computer means and recorded on a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Examples of program instructions, such as magneto-optical and ROM, RAM, flash memory and the like, can be executed by a computer using an interpreter or the like, as well as machine code, Includes a high-level language code. The hardware devices described above may be configured to operate as at least one software module to perform operations of one embodiment of the present invention, and vice versa.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: base station (BS) 110:
120: Assignment part DT, DR: D2D candidate terminal device
CUE: activated cellular terminal device

Claims (13)

1. A base station for allocating frequency resources for direct communication between devices in a cell,
A setting unit configured to set a first radius range centered on a terminal device to be directly communicated between devices and a second radius range centered on the base station; And
And an allocation unit for allocating frequency resources of the cellular terminal apparatus located in the second radius range excluding the first radius range among the activated cellular terminal apparatuses in the cell to the terminal apparatuses performing the inter-apparatus direct communication Characterized in that the base station. The method according to claim 1,
Wherein the first radius range and the second radius range are determined based on the system yield when the terminal device performing the direct communication between the devices operates in the cellular mode and the cell yield when any one of the cellular terminal devices in the cell is shared with the cellular terminal device And is set based on a system yield when operating in a direct communication mode between apparatuses. 3. The method of claim 2,
Wherein the first radius range and the second radius range are further based on a minimum SINR (Signal-to-Interference-Noise Ratio) quality of service (QoS) of a terminal device that is to perform direct communication between the apparatus and the one of the cellular terminal devices And wherein the base station is configured to transmit data to the base station. The method of claim 3,
Wherein the first radius range is inversely proportional to a distance between the terminal apparatuses to perform direct communication between the apparatuses and a distance between the terminal apparatuses to perform direct communication between the apparatuses and the base station. The method according to claim 1,
When the number of the cellular terminal devices located within the second radius range excluding the first radius range is two or more, the allocating section allocates the frequency resources of the cellular terminal devices that maximize the system yield among the two or more cellular terminal devices to the inter- And allocating the resource as a resource for the base station. The method according to claim 1,
Wherein the allocating unit allocates the frequency resources different from the frequency resources of the activated cellular terminal apparatus in the cell to the inter-apparatus direct communication when the cellular terminal apparatus located in the second radius range excluding the first radius range does not exist To the terminal device to be used for the terminal. A method of allocating a frequency resource for direct communication between devices in a cell,
Setting a first radius range centered on a terminal device to be directly communicated between devices and a second radius range centered on a base station; And
And allocating a frequency resource of the cellular terminal device located in the second radius range excluding the first radius range among the activated cellular terminal devices in the cell to the terminal device performing the inter-device direct communication . 8. The method of claim 7,
Wherein the first radius range and the second radius range are determined based on the system yield when the terminal device performing the direct communication between the devices operates in the cellular mode and the cell yield when any one of the cellular terminal devices in the cell is shared with the cellular terminal device And is set based on a system yield when operating in a direct communication mode between apparatuses. 9. The method of claim 8,
Wherein the first radius range and the second radius range are set based on a minimum SINR QoS of the terminal device to perform direct communication between the one of the cellular terminal devices and the device. 8. The method of claim 7,
Wherein when the number of the cellular terminal apparatuses located within the second radius range except for the first radius range is two or more, the allocating unit allocates the frequency resources of the cellular terminal apparatus that maximizes the system yield among the two or more cellular terminal apparatuses And allocating the resource as a resource for direct communication. 1. A terminal apparatus for performing direct communication between devices in a cell,
The mobile terminal device is located outside the first radius range centered on the terminal device among the activated cellular terminal devices in the cell and shares the frequency resources of the cellular terminal devices located within the second radius range centered on the base station, To the terminal device. 12. The method of claim 11,
Wherein the first radius range and the second radius range share a system yield when the terminal apparatus operates in a cellular mode and resources with any one of the cellular terminal apparatuses activated in the cell to set a direct communication mode Based on the system yield at the time of operation. 13. The method of claim 12,
Wherein the first radius range and the second radius range are set based on a minimum SINR (Signal-to-Interference-Noise Ratio) quality of service (QoS) of any one of the cellular terminal apparatus and the terminal apparatus .

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