KR101371181B1 - Method and apparatus for resource scheduling of device to device communication in a communication system - Google Patents

Abstract

According to an aspect of the present invention, there is provided a resource scheduling method for direct communication between terminals in a communication system. Calculating a signal-to-interference noise ratio of the mobile communication terminal on the assumption that each of the terminal pairs for direct communication between the communication terminal and the terminal located within the service coverage of the base station is allocated, and the calculated mobile communication for each channel; Comparing the signal-to-interference noise ratio of the terminal with the first threshold value, and determining terminal pairs having a signal-to-interference noise ratio exceeding the first threshold value for each channel as candidate members of a combination sharing the corresponding channel; And assigning a channel to each of the candidate members of the combination determined for each channel. Including the process of determining whether or not.

Description

Resource scheduling method and apparatus for direct communication between terminals in a communication system {METHOD AND APPARATUS FOR RESOURCE SCHEDULING OF DEVICE TO DEVICE COMMUNICATION IN A COMMUNICATION SYSTEM}

The present invention relates to a resource scheduling method and apparatus for direct communication between terminals in a communication system.

A general resource scheduling method of device-to-device communication (hereinafter, referred to as 'D2D') utilizes resources of a mobile communication system. That is, based on the centralized resource management scheme in which the base station determines resource allocation, the resources occupied by one mobile communication terminal of the terminal pair (hereinafter, referred to as 'D2D pair') for D2D A method of allocating one D2D pair by sharing with communication and a method of allocating a plurality of D2D pairs through spatial reuse between D2D pairs.

In the method of allocating the occupied resources of the mobile communication terminal to only one D2D pair, only one D2D pair is allocated to one unit resource, and thus resources for D2D communication are very limited.

In addition, in the method of allocating one unit resource to a plurality of D2D pairs through spatial reuse between the terminal pairs, feedback information required for the base station to determine a D2D pair sharing the same resource is additionally generated. As a result, since the resources of the control channel for additional feedback information are used, there is a problem that causes a decrease in cell performance. Moreover, the base station greatly increases the complexity caused when allocating a specific resource to a plurality of D2D pairs.

Therefore, there is a need for a scheduling method for allocating resources to support multiple D2D communications without reducing performance in a mobile communication system.

The present invention proposes a method and apparatus for sharing and allocating the same communication resources to multiple D2D pairs in a mobile communication system.

Method according to the practice of the present invention; A method of scheduling resources for device-to-device communication (D2D) in a communication system, the method comprising: selecting a mobile communication terminal communicating with the base station for each channel obtained by dividing a mobile communication resource occupied by a base station; Calculating a signal-to-interference noise ratio of the mobile communication terminal when each of the terminal pairs for direct communication between the selected mobile communication terminal and the terminal located within the service coverage of the base station for each channel is allocated; By comparing the signal-to-interference noise ratio of the mobile communication terminal and the first threshold value, the terminal pairs having the signal-to-interference noise ratio exceeding the first threshold value for each channel are determined as candidate members of the combination sharing the corresponding channel. And a corresponding channel for each candidate member of the combination determined for each channel. If there is no remaining candidate member to which the channel is not allocated for each channel, whether there is a channel for which the channel is not determined is determined, and whether to allocate the channel is determined. If there is at least one channel that is not determined, determining whether to allocate the channel to each of the candidate members constituting the combination corresponding to the channel for the at least one channel.

An apparatus according to an embodiment of the present invention includes: In a resource scheduling apparatus for device-to-device communication (D2D) in a communication system, a mobile communication terminal communicating with the base station is selected for each channel obtained by dividing a mobile communication resource occupied by a base station, and for each channel. An SINR calculator configured to calculate a signal-to-interference noise ratio of the mobile communication terminal when each of the terminal pairs for direct communication between the selected mobile communication terminal and the terminal located within the service coverage of the base station is allocated; By comparing the signal-to-interference noise ratio of the mobile communication terminal and the first threshold value, the terminal pairs having the signal-to-interference noise ratio exceeding the first threshold value for each channel are determined as candidate members of the combination sharing the corresponding channel. The channel is allocated to each of the candidate members of the combination determined for each channel. If there is no remaining candidate member to which the corresponding channel is not allocated for each channel, the controller determines whether there is a channel for which the corresponding channel is not determined. If at least one exists, the scheduler for determining whether to allocate the channel to each of the candidate members constituting the combination corresponding to the channel for the at least one channel.

The present invention divides a mobile communication resource occupied by a base station into a unit resource, calculates a signal-to-interference noise ratio of each of the additionally allocated D2D pairs for the mobile communication terminal for each divided unit resource, and exceeds a threshold value for a D2D pair. Assume that each D2D pair is additionally allocated for each unit resource, and further select D2D pairs exceeding a threshold by calculating a signal-to-interference noise ratio between the D2D pairs to which the unit resource is allocated. In addition, by further considering the location information of the D2D pair to which the unit resource is to be allocated, by selecting the D2D pairs to substantially allocate the unit resource, the complexity of the calculation is reduced and the performance of the mobile communication system can be reduced. While maintaining, there is an effect of sharing the unit resource among multiple D2D pairs.

1 is a view for explaining the space reuse resource allocation between the pair of terminals for D2D according to the first embodiment of the present invention.
2 is a flowchart illustrating an example of a process of configuring a resource-specific combination according to a second embodiment of the present invention.
3 is a flowchart illustrating a resource allocation process for minimizing interference among members constituting the combination according to the second embodiment of the present invention.
4 is a view for explaining a method of allocating resources to terminal pairs for D2D using location information of a terminal in a second embodiment of the present invention.
5 is a schematic structural diagram of a base station according to embodiments of the present invention.
6A is a graph comparing the number of comparison candidates according to spatial reuse resource allocation supporting D2D with an existing resource allocation according to embodiments of the present invention.
FIG. 6B is a graph comparing performance loss according to a distance between a terminal pair allocated common resource and a mobile communication terminal according to embodiments of the present invention. FIG.

The operation principle of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. The same elements shown in the drawings are denoted by the same reference numerals even though they are shown in different drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention unclear. The detailed description thereof will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

The present invention proposes a resource allocation method for device-to-device communication (hereinafter, referred to as 'D2D') so that a feedback overhead is not increased while maintaining the performance of a mobile communication system. .

Specifically, the present invention is largely divided into three examples. A first embodiment of the present invention selects candidate members of a combination that share a unit resource obtained by dividing a mobile communication resource with a corresponding mobile communication terminal, that is, terminal pair candidates (hereinafter, referred to as 'D2D pair') candidates for D2D. . In the second embodiment of the present invention, it is determined whether to substantially allocate the corresponding unit resource to the candidate members selected for each combination based on the channel information. In the third embodiment of the present invention, it is determined whether to substantially allocate the corresponding unit resource to the candidate members selected for each combination based on the location information.

Candidates Sharing Resources with Mobile Communications D2D Pairs  How to choose>

The first embodiment of the present invention proposes a method of determining a D2D pair candidate for sharing a corresponding unit resource for sharing a unit resource used for mobile communication with a plurality of D2D pairs through spatial reuse. Specifically, when the distance between the mobile communication terminal and the D2D pairs located in the same service coverage as the mobile communication terminal is sufficiently far from each other, the interference between the mobile communication terminals becomes small. Therefore, D2D pairs located at a distance sufficiently separated from each other with respect to the corresponding mobile communication terminal are selected as members of candidate combinations (hereinafter, referred to as candidate D2D pairs) for sharing resources with the mobile communication terminal. By doing so, space reuse can be performed.

1 is a diagram illustrating a method of selecting candidate D2D pairs for each combination of sharing resources with mobile communication according to the first embodiment of the present invention.

1, a base station 102 for allocating resources for mobile communication and D2D in a service coverage 100 of a mobile communication system, and mobile communication terminals 1, 2, 3, 4 (104, 106, 108, 110). ) And D2D pairs (D2D 1, D2D 2, D2D 3, D2D 4) 112, 114, 116, and 118.

For example, the base station 102 divides resources allocated to D2D communication among the total resources occupied for mobile communication into unit resources, and the mobile communication terminals 1, 2, 3, and 4 (for each divided resource). A mobile communication terminal that satisfies a predetermined criterion among the 104, 106, 108, and 110 is allocated to the mobile communication terminal to use the corresponding unit resource. For example, the signal-to-interference calculated based on the assumption that each of the mobile communication terminals 1, 2, 3, and 4 (104, 106, 108, 110) uses the corresponding channel alone without sharing with another D2D pair. The case may be a case in which a signal to interference-plus-noise ratio (SINR) is satisfied. Hereinafter, in the present specification, the channel is used as the same meaning as the divided unit resource.

Next, candidate D2D pairs to be allocated by overlapping channels allocated to the mobile communication terminals 1, 2, 3, and 4 (104, 106, 108, and 110) are selected to form a combination. Specifically, the base station 102 is a D2D pair of each of the D2D 1, D2D 2, D2D 3, D2D 4 (112, 114, 116, 118) based on the state that only the corresponding mobile communication terminal is allocated for each channel Assuming an additional allocation to the channel, the SINR of the mobile communication terminal (hereinafter referred to as SINR of the mobile communication terminal perspective) is calculated using Equation 1 below.

은 이동 통신 단말 c에게 자원 r이 할당된 경우, 이동 통신 단말 C관점의 SINR을 나타내고, P_{c ,r}는 이동 통신 단말 c가 자원 r을 사용하는 경우의 송신 전력을 나타내고, P_{m ,r}는 D2D 페어 m이 자원 r을 사용하는 경우의 송신 전력을 나타내고, G_{cB ,r}은 자원 r이 할당된 경우 이동 통신 단말 c와 기지국B 사이의 채널 이득값을 나타내고,

은 이동 통신 단말 c에게 할당된 자원을 단말 페어 m과 공유하는지 여부를 나타내는 지시자로, 공유하는 경우 1, 공유하지 않는 경우 0 값을 갖는 이진 변수이다.Where c denotes a mobile communication terminal indicator, m denotes an indicator of a D2D pair, B denotes an indicator of a base station, r denotes an occupied resource of the base station, N ₀ denotes a value in consideration of thermal noise of a receiver, and I denotes Indicates an interference value of an adjacent cell,

When resource r is assigned to mobile communication terminal _{c ,} SINR of the mobile communication terminal C viewpoint is represented, P _{c , r} represents transmission power when mobile communication terminal c uses resource r, and P _{m , r} is Transmit power when the D2D pair m uses the resource r, G _{cB , r} indicates the channel gain value between the mobile communication terminal c and the base station B when the resource r is allocated,

Is an indicator indicating whether the resource allocated to the mobile communication terminal c is shared with the terminal pair m, and is a binary variable having a value of 1 for sharing and 0 for no sharing.

For each of the D2D 1, D2D 2, D2D 3, and D2D 4 (112, 114, 116, 118), the SINR of the mobile communication terminal perspective calculated using Equation 1 exceeds the first threshold value. A D2D pair that satisfies the condition is selected as candidate members of a combination that can share resources with the mobile communication terminal in the corresponding channel.

For example, when only mobile communication terminal 1 104 is allocated to channel 1, the mobile communication terminal 1 104 and the D2D 1, D2D 2, D2D 3, and D2D 4 (112, 114, and 116) are assigned to channel 1. Suppose that each of them is allocated, the mobile communication terminal 1 for each of the D2D 1, D2D 2, D2D 3, D2D 4 (112, 114, 116, 118) using Equation 1 104) Calculate the SINR of the point of view. In this case, it is assumed that the SINR of the mobile communication terminal 1 104 viewpoint for each of the D2D 3 116 and the D2D 4 118 satisfies a condition exceeding the first threshold value. The candidate members of the combination that share channel 1 then consist of the D2D 3 116 and D2D 4 118.

On the other hand, it is assumed that each of the D2D 1, D2D 2, D2D 3, D2D 4 (112, 114, 116, 118) is allocated to the channel 2 while only the mobile communication terminal 4 (110) is allocated to the channel 2. In addition, the SINRs of the mobile communication terminal 4 (110) viewpoint for each of the D2D 1, D2D 2, D2D 3, and D2D 4 (112, 114, 116, 118) calculated using Equation 1 are all the above. Suppose it is greater than or equal to the first threshold. Then, in the case of the mobile communication terminal 4 (110), the interference with respect to the D2D 1, D2D 2, D2D 3, D2D 4 (112, 114, 116, 118) is not large. Accordingly, the base station 102 determines the D2D 1, D2D 2, D2D 3, and D2D 4 (112, 114, 116, 118) as candidate members of the combination sharing the channel 2. FIG.

In the manner as described above, candidate members of a combination, that is, candidate D2D pairs, sharing a channel allocated to each of the mobile communication terminals 1, 2, 3, and 4 (104, 106, 108, 110) are determined.

2 is a flowchart illustrating an example of a process of determining candidate D2D pairs of a channel-specific combination according to the first embodiment of the present invention.

Referring to FIG. 2, in step 200, the base station divides resources occupied for mobile communication into unit resources (hereinafter, referred to as 'channels'). The mobile communication terminal is allocated according to a predetermined criterion for each channel divided. Here, as an example of the criterion, a case in which a corresponding mobile communication terminal is assigned to each channel alone may be satisfied when the SINR of the mobile communication terminal has a maximum value.

In step 205, the base station assumes a case in which the corresponding mobile communication terminal allocated for each channel shares a resource with each of the D2D pairs located within the service coverage of the base station. Accordingly, the base station calculates the SINR of the mobile communication terminal perspective when each of the D2D pairs is allocated to each of the channels based on the corresponding mobile communication terminal using Equation 1.

In step 210, the base station determines, for each channel, D2D pairs whose SINR from the perspective of the mobile communication terminal exceeds the first threshold value as candidate members of a combination sharing resources of the corresponding channel.

<Method of selecting a D2D pair to allocate resources substantially among candidate D2D pairs for each combination based on channel information>

When using the space reuse resource allocation method according to the first embodiment of the present invention, each of the unit resources occupied for mobile communication in the mobile communication system can be shared with a plurality of D2D pairs. However, due to the large number of D2D pairs sharing the unit resource, mutual interference between the plurality of D2D pairs occurs. In addition, when a corresponding unit resource is allocated to all subsets of candidate D2D pairs for each combination, it is required to confirm whether the reference performance of the mobile communication and the D2D communication is satisfied. The verification procedure must be performed for all subsets of candidate D2D pairs for each combination, which leads to a considerably higher computational complexity. Therefore, in the second embodiment of the present invention, it is possible to calculate with a lower complexity whether or not the reference performance due to the interference between the candidate D2D pairs for each combination sharing the corresponding unit resources and the interference with the mobile communication terminal is satisfied. A method of scheduling a spatial space reuse is proposed. FIGS. 3A and 3B illustrate D2D pairs (hereinafter, referred to as 'resource sharing D2D pairs') to which a corresponding resource is substantially allocated among candidate D2D pairs for each combination according to the second embodiment of the present invention. ) Is a flowchart illustrating an example of a process of selecting). Herein, it is assumed that the base station determines a mobile communication terminal to allocate a corresponding channel for each channel and candidate members of a combination to share resources with the mobile communication terminal according to the first embodiment described above.

Referring to FIG. 3A, in step 300, the base station divides resources occupied for mobile communication into unit resources (hereinafter, referred to as 'channels'). For convenience of description, a first combination including all candidate members of the combination corresponding to the corresponding channel determined in step 210 is selected for one of the divided channels. Here, the order in which the base station selects any channel among all the channels does not have much relation with the present invention, and thus detailed description thereof will be omitted. In addition, although one channel of the divided channels is described herein for convenience of description, the procedure of FIG. 3A is equally applied to each of the divided channels.

In step 305, the base station selects the first D2D pair having the maximum value by sorting in order of SINR size from the perspective of the mobile communication terminal with respect to candidate members of the first combination. The SINR of the mobile communication terminal viewpoint for the candidate members of the first combination is assumed that a channel corresponding to the first combination is assigned only to each of the predetermined mobile communication terminal and candidate members of the first combination. It is calculated according to <Equation 1>.

In step 310, it is assumed that a channel corresponding to the first combination is additionally allocated to the first D2D pair. The base station calculates an SINR from the perspective of the mobile communication terminal when a channel corresponding to the first combination is additionally allocated to the first D2D pair according to Equation (1). If at least one D2D pair, in which a channel corresponding to the first combination is already allocated, exists, the SINR from the viewpoint of the mobile communication terminal indicates that the channel corresponding to the first combination corresponds to the mobile communication terminal; It is calculated on the assumption that there is at least one D2D pair present and the first D2D pair.

In step 315, the base station compares whether the SINR of the mobile communication terminal point of view when the channel corresponding to the first combination is additionally allocated to the first D2D pair exceeds the first threshold. If the comparison result is less than or equal to the first threshold value, the base station determines not to allocate a channel corresponding to the first combination to the first D2D pair in operation 320. In operation 335, the first D2D pair is deleted from candidate members of the first combination. In operation 345, the method checks whether candidate members of the first combination, which have not been determined to allocate resources, remain.

As a result of the comparison, when the SINR of the mobile communication terminal view in the case where a channel corresponding to the first combination is additionally allocated to the first D2D pair exceeds the first threshold value, the base station determines in Equation 3 below. 2> is used to calculate the SINR of the first D2D pair (hereinafter referred to as 'SINR in view of the D2D pair'). In this case, the SINR of the first D2D pair view indicates the SINR of the first D2D pair when the channel corresponding to the first combination is used with the predetermined mobile communication terminal. In addition, assuming that a channel corresponding to the first combination is additionally allocated to the first D2D pair, and includes the first D2D pair, the SINR in view of D2D pairs to which the channel corresponding to the first combination is allocated. It is also calculated using the following Equation 2.

은 D2D 페어 m에게 자원 r이 할당된 경우, D2D 페어 m 관점의 SINR을 나타내고, P_{c ,r}는 이동 통신 단말 c가 자원 r을 사용하는 경우의 송신 전력을 나타내고, P_{m ,r}는 D2D 페어 m이 자원 r을 사용하는 경우의 송신 전력을 나타내고, G_{cm ,r}은 자원 r이 할당된 경우 이동 통신 단말 c와 단말 페어 m 사이의 채널 이득값을 나타내고, G_{mm' ,r}은 자원 r이 할당된 경우 단말 페어 m 및 m' 사이의 채널 이득값을 나타내고,

은 이동 통신 단말 c에게 할당된 자원을 단말 페어 m과 공유하는지 여부를 나타내는 지시자로, 공유하는 경우 1, 공유하지 않는 경우 0 값을 갖는 이진 변수이다.Herein, m is an indicator of a D2D pair to additionally allocate resource r, and m 'is an indicator of a D2D pair that has already shared r with the corresponding mobile communication terminal.

When resource r is assigned to D2D pair m, it represents SINR from the viewpoint of D2D pair m, P _{c , r} indicates transmission power when mobile communication terminal c uses resource r, and P _{m , r} is D2D pair m denotes a transmission power when resource r is used, G _{cm , r} denotes a channel gain value between mobile communication terminal c and terminal pair m when resource r is allocated, and G _{mm ' , r} denotes resource r If assigned, it represents the channel gain between the terminal pair m and m ',

Is an indicator indicating whether the resource allocated to the mobile communication terminal c is shared with the terminal pair m, and is a binary variable having a value of 1 for sharing and 0 for no sharing.

In step 330, the base station determines that the SINR of the first D2D pair and the SINR of the D2D pairs to which the channel corresponding to the first combination including the first D2D pair is allocated are the second threshold. Compare if exceeded. When the comparison result indicates that at least one of the SINR of the viewpoint of the first D2D pair and the SINR of the viewpoint of D2D pairs to which the unit resource of the first combination including the first D2D pair is allocated is equal to or less than the second threshold, the base station performs step 320. Proceed to In operation 320, the channel corresponding to the first combination is further determined not to be allocated to the first D2D pair, and in step 335, the first D2D pair is deleted from candidate members of the first combination selected. In operation 345, the method determines whether there is a candidate member of the first association whose resource allocation is not determined.

As a result of the comparison, when both the SINR of the first D2D pair view and the SINR of the D2D pairs view in which the channel corresponding to the first combination including the first D2D pair are allocated exceed the second threshold, the operation proceeds to step 340. The base station allocates the channel corresponding to the first combination to the first D2D pair. In step 335, the base station deletes the first D2D pair from candidate members of the first combination, and proceeds to step 345.

In step 345, the base station determines whether candidate members of the first combination remain unresolved. If there is a candidate member of the first association whose resource allocation has not been determined as a result of the checking, the process returns to step 305. In step 305, the base station selects a D2D pair having a maximum SINR of a mobile communication terminal from among candidate members of the first combination from which the first D2D pair is deleted. The base station repeats steps 310 to 345.

If it is determined in step 345 whether resource allocation is determined for all candidate members of the first combination, the process proceeds to step 350. Referring to FIG. 3B, in step 350, the base station determines whether all channels divided in step 300 are allocated to all D2D pairs located in its service coverage. As a result of the check, if there is a D2D pair for which all channels have not been determined, the process returns to step 300. In step 300, the base station selects one of channels for which resource allocation is not determined according to a predetermined criterion, and repeats steps 305 to 345. If it is determined in step 350 whether resource allocation of all channels is determined for all of the D2D pairs located in the service coverage, the base station terminates the resource allocation procedure for each channel.

As described above, according to the procedure shown in FIGS. 3A and 3B, the base station determines whether resource allocation of all the channels is performed for all candidate members of each combination corresponding to all channels for all D2D pairs located in its service coverage. Repeat steps 300 to 345 until it is determined.

When a resource allocation procedure is performed to a candidate member for each combination as described above, if a resource is allocated regardless of whether another channel is already allocated to the candidate member, a plurality of D2D pairs within the service coverage of the base station are determined. D2D pairs may occur in which channels are assigned simultaneously. In this case, whether to use the plurality of channels may be determined autonomously by the D2D pair to which the plurality of channels are allocated.

<Based on location information Combination star  candidate D2D Fair  Resource allocation to actually allocate resources D2D Pair  How to choose>

According to the embodiment of the present invention as described above, channel information between D2D pairs sharing a corresponding resource is additionally required. The channel information increases in proportion to the square of the number of D2D pairs as the number of D2D pairs increases. Therefore, a method of reducing cell performance by preventing the use of additional channel transmission should be considered.

In addition, when a plurality of D2D pairs share the same channel according to an embodiment of the present invention, the D2D pairs must be sufficiently spaced apart to reduce interference with each other, thereby increasing performance.

Therefore, according to the third embodiment of the present invention, in order to reduce channel information feedback between D2D pairs, location information of terminals located within service coverage of the base station is acquired in advance, and a resource allocation method using the same is proposed. In the third embodiment of the present invention, a global positioning system (GPS) or a direction of arrival (DOA) estimation is used to obtain a position of a corresponding terminal.

For example, when the terminal is equipped with a GPS such as a smart phone, the terminal may acquire location information of the terminal through the mounted GPS. In this case, the base station collects its own location information obtained by each of the terminals through the GPS. Assuming that the location information is correct, the base station selects a D2D pair including a terminal that has transmitted the location information sufficiently spaced apart from the location of the mobile communication terminal with respect to the mobile communication terminal that has obtained the location information, and selects the selected D2D. A pair is scheduled to share resources allocated to the mobile communication terminal. In this case, there is a disadvantage that it is difficult for the base station to obtain location information for the terminal that does not have GPS embedded therein.

Therefore, the third embodiment of the present invention also includes a case of acquiring the positions of the terminals through the DOA estimation method in order to obtain the positions of the terminals without GPS assistance.

FIG. 4A is a diagram for describing a method of allocating resources to D2D pairs using location information of a terminal in a third embodiment of the present invention.

Referring to FIG. 4A, there is a mobile communication terminal 404 and D2D pairs, that is, D2D 1 406, D2D 2 408, and D2D 3 410 within the service coverage 400 of the base station 402. .

The base station 402 uses the DOA estimation for the mobile communication terminal 404 and the terminals constituting the D2D 1 406, the D2D 2 408, and the D2D 3 410, respectively. Obtain location information. For the DOA estimation, the base station 402 may use a reference signal such as a preamble or pilot for random access.

For example, the base station 402 estimates an angle of the mobile communication terminal 404 and an average angle of each of the D2D 1 406, the D2D 2 408, and the D2D 3 410 through DOA estimation. Here, the average angle means DOA estimation of the median value of the distance between the two pairs of terminals constituting the D2D 1 406, the D2D 2 408, and the D2D 3 410, respectively. Then, based on the estimated DOA, the base station 402 assigns the resource allocated to the mobile communication terminal 204 to a terminal pair whose DOA between the mobile communication terminal 404 and the terminal pair exceeds a preset threshold angle. Assign.

4B is a flowchart illustrating an example of a process of selecting a resource sharing D2D pair to which a corresponding resource is substantially allocated among candidate D2D pairs for each combination by using location information according to a third embodiment of the present invention. Herein, it is assumed that the base station determines a mobile communication terminal to allocate a corresponding channel for each channel and candidate members of a combination to share resources with the mobile communication terminal according to the first embodiment described above.

Referring to FIG. 4B, in step 400, the base station divides resources occupied for mobile communication into unit resources. For convenience of description, a first combination including all candidate members of the combination corresponding to the corresponding channel determined in step 210 is selected for one of the divided channels. Here, the order in which the base station selects any channel among all the channels does not have much relation with the present invention, and thus detailed description thereof will be omitted. In addition, although one channel of the divided channels is described herein for convenience of description, the procedure of FIG. 4B is equally applied to each of the divided channels.

In step 405, the base station selects the first D2D pair having the largest SINR among the members of the first combination by sorting the candidate members of the first combination in the order of SINR size from the perspective of the mobile communication terminal. The SINR of the mobile communication terminal viewpoint for the candidate members of the first combination is assumed to be assigned only to each of the predetermined mobile communication terminal corresponding to the first combination and the candidate members of the first combination. Calculated according to equation 1>.

In step 410, it is assumed that a channel corresponding to the first combination is additionally allocated to the first D2D pair. The base station calculates an SINR from the perspective of the mobile communication terminal when a channel corresponding to the first combination is additionally allocated to the first D2D pair according to Equation (1). If there is at least one D2D pair in which a channel corresponding to the first combination is already present, the SINR from the viewpoint of the mobile communication terminal indicates that the channel corresponding to the first combination is the mobile communication terminal and the It is calculated on the assumption that there is at least one D2D pair present and the first D2D pair.

In step 415, the base station compares whether the SINR of the mobile communication terminal view exceeds the first threshold when a channel corresponding to the first combination is additionally allocated to the first D2D pair. If the comparison result is less than or equal to the first threshold value, the base station determines not to allocate a channel corresponding to the first combination to the first D2D pair in operation 420. In operation 435, the first D2D pair is deleted from candidate members of the first combination. In operation 445, it is determined whether candidate members of the first association that have not been determined to allocate resources remain.

As a result of the comparison, when the SINR of the mobile communication terminal perspective when the channel corresponding to the first combination is additionally allocated to the first D2D pair exceeds the first threshold value, the base station determines in step 425 the first D2D pair. And a distance between the D2D pairs to which the unit resource of the first combination is allocated. In this case, when there are a plurality of D2D pairs to which a channel corresponding to the first combination is allocated, a distance from the first D2D pair is calculated for each of the plurality of D2D pairs. The distance between the D2D pairs configures each of the D2D pairs to which the channel or the channel corresponding to the first combination has already been assigned, as shown in FIG. It is defined as the difference between the median of the position or angle of the two terminals, or the minimum value of the distance or angle between the terminals.

In step 430, the base station compares whether there is a distance equal to or less than a third threshold value among distances between the first D2D pair and each of the D2D pairs to which the unit resource of the first combination is allocated. As a result of the comparison, when there is at least one distance that is less than or equal to the third threshold value among the calculated D2D pairs, in step 420, the base station further provides a channel corresponding to the first combination to the first D2D pair. Decide not to allocate. In step 435, the base station deletes the first D2D pair from candidate members of the first combination. In operation 445, it is determined whether candidate members of the first association that have not been determined to allocate resources remain.

As a result of the comparison in step 430, when all of the calculated distances between the D2D pairs exceed the third threshold, in step 440, the base station allocates the channel corresponding to the first combination to the first D2D pair. In operation 435, the first D2D pair is deleted from candidate members of the first combination, and then operation 445 is performed.

In step 445, the base station determines whether there are remaining candidate members of the first combination whose resource allocation is not determined. If there is a candidate member of the first combination whose resource allocation is not determined as a result of the checking, the process returns to step 405. In step 405, the base station selects a D2D pair having a maximum SINR from the perspective of a mobile communication terminal among candidate members of the first combination from which the first D2D pair is deleted. The base station repeats steps 410 to 445.

If it is determined in step 445 whether resource allocation is determined for all candidate members of the first combination, in step 450, the base station determines all channels divided in step 400 for all D2D pairs located within its service coverage. Make sure that they have been assigned. If there is a D2D pair for which all channels have not been determined as a result of the check, the process returns to step 400. In step 400, the base station selects one of channels for which resource allocation is not determined according to a predetermined criterion, and repeats steps 405 to 445. When it is determined in step 450 whether resource allocation of all channels is determined for all of the D2D pairs located in the service coverage, the base station terminates the resource allocation procedure for each channel.

As described above, according to the procedure shown in FIG. 4B, the base station repeats steps 400 to 445 until it is determined whether to assign a channel corresponding to the combination for candidate members for each combination for all channels.

When a resource allocation procedure is performed to a candidate member for each combination as described above, if a resource is allocated regardless of whether another channel is already allocated to the candidate member, a plurality of D2D pairs within the service coverage of the base station are determined. D2D pairs may occur in which channels are assigned simultaneously. In this case, whether to use the plurality of channels may be determined autonomously by the D2D pair to which the plurality of channels are allocated. 5 is a schematic structural diagram of a base station according to embodiments of the present invention.

Referring to FIG. 5, the base station 500 includes a receiver 505, an SINR calculator 510, and a scheduler 515.

The receiver 505 receives location information from each of the mobile communication terminals located within the service coverage of the base station 500 and the terminals constituting the D2D pair. Alternatively, the receiving unit 505 obtains the response information by the reference signal or the preamble transmitted by the base station 500 as the location information. Here, the location information may be obtained through GPS of the corresponding terminal or may be obtained through DOA estimation.

Then, the scheduler 515 according to the third embodiment of the present invention uses the location information to determine whether to allocate the unit resource to candidate members for each combination. In this case, as shown in FIG. 4A, the scheduler 515 has a median value of a distance between two terminals constituting a candidate member for determining whether to additionally allocate the current channel and a D2D to which the current channel has already been allocated. After comparing the third threshold with the distances defined by the difference between the median values of the distances between the two terminals constituting each pair, the current channel is only available to candidate members whose calculated distance exceeds the third threshold. Allocate If at least one of the calculated distances is less than or equal to the third threshold value, it is determined that the corresponding unit resource is not allocated to the candidate member.

The SINR calculator 510 calculates an SINR when only a corresponding mobile communication terminal is allocated to each channel. The SINR calculator 510 allocates a mobile communication terminal having a maximum value among SINRs of the calculated mobile communication terminal viewpoint to each channel for each channel.

In addition, the SINR calculator 515 according to the first embodiment of the present invention is a mobile communication terminal when each of the D2D pairs located in the service coverage of the base station 500 and a predetermined mobile communication terminal are allocated to each channel. The SINR of the viewpoint is calculated using Equation 1 above. In addition, the SINR calculator 515 selects the D2D pair having the SINR of the mobile communication terminal viewpoint exceeding a first threshold value among the SINRs of the mobile communication terminal viewpoint calculated for each of the channels, and the candidate members of the channel. Decide on

As described above, when candidate members are determined for each channel, the SINR calculator 510 determines whether to substantially allocate the corresponding channel to each of the candidate members for each channel. Specifically, the SINR calculation unit 510 according to the second embodiment of the present invention targets candidate members of the selected channel and assumes that each candidate member is additionally assigned to the selected channel. SINR from the perspective of the mobile communication terminal according to &gt; is selected to select a case not exceeding the first threshold value. If the SINR of the mobile communication terminal view does not exceed the first threshold value, the scheduler 515 determines not to allocate the channel to the candidate member, and among the candidate members of the channel. Delete it. If the SINR of the mobile communication terminal viewpoint exceeding the first threshold value is a candidate member having a maximum value, the SINR calculation unit 510 assumes that the candidate member has been assigned to the candidate member. The SINR of the corresponding D2D pair viewpoint is calculated using Equation 2 above. The SINR of the D2D pairs including the candidate member already allocated to the channel is calculated. Thereafter, the scheduler compares whether the SINR of the D2D pair view corresponding to the candidate member and the SINR of the D2D pairs already allocated to the corresponding unit resource exceed the second threshold. As a result of the comparison, the channel is allocated to the candidate member only when the SINR of the D2D pair view corresponding to the candidate member and the SINR of the D2D pairs already allocated to the corresponding unit resource exceed the second threshold. . And, the base station 500 repeats the operation whether or not resource allocation for each of the D2D pairs located in its service coverage.

6A is a graph comparing the number of candidate members to be compared with existing resource allocations according to spatial reuse resource allocation supporting D2D according to embodiments of the present invention.

Referring to FIG. 6A, when performing resource allocation for D2D without considering overlapping allocation for each channel, that is, resource sharing, according to the existing scheduling method, the number of candidate D2D pairs to allocate resources for each channel should be compared. It can be seen that the number of candidates increases linearly. On the other hand, when performing spatial reuse resource allocation for D2D in consideration of sharing resources for each channel as in the embodiments of the present invention, the number of candidates to be compared is increased as the number of candidate D2D pairs to share resources for each channel increases. It can be seen that it increases exponentially.

6B is a graph comparing performance loss according to a distance between a D2D pair to which a common resource is allocated and a mobile communication terminal according to embodiments of the present invention.

Referring to FIG. 6B, it can be seen that the greater the distance between the D2D pair sharing the resources of the mobile communication terminal and the mobile communication terminal, the lower the performance loss.

As a result, when using the third embodiment of the present invention, the number of candidate D2D pairs to be compared does not increase significantly compared to the existing scheme, and the performance of the mobile communication terminal sharing resources is reached.

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

Claims (16)

In the resource scheduling method for device-to-device communication (D2D) in a communication system,
Selecting a mobile communication terminal for communicating with the base station for each channel in which the mobile communication resources occupied by the base station are divided;
Calculating a signal-to-interference noise ratio of the mobile communication terminal assuming that each of the terminal pairs for direct communication between the selected mobile communication terminal and the terminal located within the service coverage of the base station are allocated for each channel;
Combining the pairs of terminals having a signal-to-interference noise ratio exceeding the first threshold for each channel by comparing the calculated signal-to-interference noise ratio and the first threshold value for each channel. The process of determining as a candidate member of,
Determining whether to allocate a corresponding channel to each of the candidate members of the combination determined for each channel;
If there is no remaining candidate member to which the corresponding channel is not allocated for each channel, check whether there is a channel that has not been determined to allocate the channel, and if there is at least one channel that has not been determined to allocate the channel. And determining whether to allocate a corresponding channel to each of the candidate members constituting a combination corresponding to the corresponding channel with respect to the at least one channel.
The method of claim 1,
The process of determining whether to allocate the channel to each of the candidate members of the combination determined for each channel includes:
Select a first channel to perform resource allocation for the D2D of the channel, select a first combination consisting of all candidate members of the combination corresponding to the first channel, the first channel is the first combination Calculating a signal-to-interference noise ratio of the mobile communication terminal to which the first channel is allocated for each of the candidate members of the first combination, assuming a case allocated to each of the candidate members of the first combination;
Selecting a first terminal pair having a maximum value among the signal-to-interference noise ratios of the mobile communication terminal, and comparing the maximum value with the first threshold value;
If the comparison result is less than or equal to the first threshold value, it is determined not to allocate the first channel to the first terminal pair, the first terminal pair is removed from candidate members of the first combination, and the first terminal pair. Checking whether there is a remaining candidate member for which the first channel is not allocated among candidate members of the first combination except for;
And determining that the first candidate channel is additionally allocated to the remaining candidate members when the remaining candidate members exist as a result of the checking.
The first terminal pair and the first channel are allocated on the assumption that the first channel is allocated to the first terminal pair when the comparison results exceed the first threshold. Calculating a first signal-to-interference noise ratio between mobile communication terminals, and calculating a second signal-to-interference noise ratio between the first terminal pair and terminal pairs that have already been allocated the first channel;
Comparing the first signal to interference noise ratio and the second signal to interference noise ratio with a second threshold value;
As a result of the comparison, when the first signal to interference noise ratio and the second signal to interference noise ratio exceeds the second threshold value, the step of assigning the first channel to the first terminal pair directly between terminals comprising the Resource scheduling method for communication.
The method of claim 3,
As a result of the comparison, the first signal to interference noise ratio and the second signal to interference noise ratio At least one of Determining not to allocate the first channel to the first terminal pair when the second threshold value is less than the second threshold value, and removing the first terminal pair from candidate members of the first combination;
If there is the remaining candidate members of the candidate members of the first combination except the first terminal pair, direct communication between the terminals further comprising the step of determining whether to assign the first channel to the remaining candidate members Resource scheduling method.
The method of claim 3,
Determining whether to allocate the channel to each of the candidate members constituting the combination corresponding to the channel for the at least one channel,
Assigning the first channel to the first terminal pair, deleting the first terminal pair from candidate members of the first combination, and checking whether the remaining candidate members exist;
If the remaining candidate members do not exist, checking whether there is a channel for which the corresponding channel is not determined for the terminal pairs located within the service coverage of the base station;
As a result of the check, when there is at least one channel for which the channel is not determined, whether to allocate the channel to each of the candidate members constituting the combination corresponding to the channel for the at least one channel Resource scheduling method for the direct communication between the terminal comprising the step of determining.
The method of claim 1,
The process of determining whether to allocate the channel to each of the candidate members of the combination determined for each channel includes:
Select a first channel to perform resource allocation for the D2D of the channel, select a first combination consisting of all candidate members of the combination corresponding to the first channel, the first channel is the first combination Calculating a signal-to-interference noise ratio of the mobile communication terminal to which the first channel is allocated for each of the candidate members of the first combination, assuming a case allocated to each of the candidate members of the first combination;
Calculating a distance between the first terminal pair and each of the terminal pairs to which the first channel is allocated when the signal-to-interference noise ratio of the mobile communication terminal to which the first channel is allocated exceeds the first threshold. and,
Allocating the first channel to the first terminal pair if all of the calculated distances exceed a third threshold value;
And determining that the first channel pair is not additionally allocated to the first terminal pair when at least one of the calculated distances is equal to or less than the third threshold value. Resource scheduling method.
The method according to claim 6,
The distance between the first terminal pair and each of the terminal pairs to which the first channel is allocated is a location information value estimated by each of the terminals constituting the first terminal pair and each of the terminal pairs to which the first channel is allocated. Receiving by the base station or acquiring one or more pieces of information of the direction of arrival of each of the terminals measured by the base station.
In the resource scheduling device for device-to-device communication (D2D) in a communication system,
Selecting a mobile communication terminal for communicating with the base station for each channel in which a mobile communication resource occupied by a base station is divided, and each of the terminal pairs for direct communication between the selected mobile communication terminal and terminals located within a service coverage of the base station for each channel. If is assigned, the SINR calculation unit for calculating the signal-to-interference noise ratio of the mobile communication terminal,
Combining the pairs of terminals having a signal-to-interference noise ratio exceeding the first threshold for each channel by comparing the calculated signal-to-interference noise ratio and the first threshold value for each channel. Determine as a candidate member of, determine whether to allocate the channel to each of the candidate members of the combination determined for each channel, and if there are no remaining candidate members to which the channel is not allocated for each channel, Candidate members constituting a combination corresponding to the corresponding channel for the at least one channel, when the presence or absence of the channel for which the channel is not determined is determined and at least one channel for which the channel has not been determined exists. Direct communication between terminals including a scheduler that determines whether to allocate a channel to each Resource Scheduling Device.
9. The method of claim 8,
Select a first channel to perform resource allocation for the D2D of the channel, select a first combination consisting of all candidate members of the combination corresponding to the first channel, the first channel is the first combination Assuming that the candidate channel is assigned to each of the candidate members of the SINR calculator, the signal-to-interference noise ratio of the mobile communication terminal to which the first channel is allocated is calculated for each of the candidate members of the first combination,
The scheduler selects a first terminal pair having a maximum value among signal-to-interference noise ratios of the mobile communication terminal, compares the maximum value with the first threshold value, and when the comparison result is less than or equal to the first threshold value. Determine not to allocate the first channel to the first terminal pair, remove the first terminal pair from candidate members of the first combination, and candidate members of the first combination except the first terminal pair And checking whether there is a remaining candidate member whose allocation of the first channel is not determined, and if the remaining candidate member exists, determining whether to further allocate the first channel to the remaining candidate member. Resource scheduling apparatus for direct communication between terminals. 10. The method of claim 9,
When the comparison result exceeds the first threshold, the SINR calculation unit assumes that the first channel is allocated to the first terminal pair, and the first terminal pair and the first channel are allocated mobile communication. Calculating a first signal-to-interference noise ratio between terminals, calculating a second signal-to-interference noise ratio between the first terminal pair and terminal pairs that have already been allocated the first channel,
The scheduler compares the first signal to interference noise ratio and the second signal to interference noise ratio with a second threshold, and as a result of the comparison, the first signal to interference noise ratio and the second signal to interference noise ratio When the second threshold value is exceeded, the resource scheduling apparatus for direct communication between terminals, wherein the first channel is allocated to the first terminal pair.
11. The method of claim 10,
The scheduler includes:
As a result of the comparison, the first signal to interference noise ratio and the second signal to interference noise ratio At least one of If it is less than the second threshold, it is determined not to allocate the first channel to the first terminal pair, remove the first terminal pair from candidate members of the first combination, and exclude the first terminal pair. And when the remaining candidate members of the first combination exist, determining whether to further allocate the first channel to the remaining candidate members.
11. The method of claim 10,
The scheduler includes:
Assigning the first channel to the first terminal pair, deleting the first terminal pair from candidate members of the first combination, and checking whether the remaining candidate members exist;
If the remaining candidate member does not exist as a result of the checking, it is determined whether a channel for which the corresponding channel is not determined is allocated to the terminal pairs located within the service coverage of the base station. If there is at least one channel that has not been determined whether the terminal, characterized in that for determining whether to allocate the channel to each of the candidate members constituting the combination corresponding to the channel for the at least one channel Resource scheduling device for direct communication between two resources.
9. The method of claim 8,
The scheduler selects a first channel to perform resource allocation for D2D among the channels, selects a first combination including all candidate members of the combination corresponding to the first channel, and selects the first channel. Assuming a case allocated for each of the candidate members of the first combination, a signal-to-interference noise ratio of the mobile communication terminal to which the first channel is allocated is calculated for each of the candidate members of the first combination, and the first combination is calculated. When the signal-to-interference noise ratio of the mobile communication terminal to which a channel is allocated exceeds the first threshold value, the distance between the first terminal pair and each of the terminal pairs to which the first channel is allocated is calculated, and the calculated If both distances exceed a third threshold, the first channel pair is further allocated to the first terminal pair,
If there is at least one of the calculated distances less than or equal to the third threshold value, it is determined that the first channel pair is not additionally allocated to the first terminal pair. Resource scheduling device.
14. The method of claim 13,
The distance between the first terminal pair and each of the terminal pairs to which the first channel is allocated is a location information value estimated by each of the terminals constituting the first terminal pair and each of the terminal pairs to which the first channel is allocated. Is obtained by the base station or obtained by using one or more of the information (Direction Of Arrival) of each of the terminals measured by the base station resource scheduling apparatus for direct communication between terminals. The method of claim 1,
The process of determining whether to allocate the channel to each of the candidate members of the combination determined for each channel includes:
For each of the candidate members of the combination determined for each channel, the maximum value is obtained by calculating a signal-to-interference noise ratio of the mobile communication terminal to which the channel is allocated, and when the maximum value exceeds the first threshold value, the maximum value. If the distance between the first terminal pair having a value and each of the candidate members except the first terminal pair among the candidate members of the combination determined for the channel is calculated, and all of the calculated distances exceed the third threshold value, And a method of allocating the channel to the first terminal pair.
9. The method of claim 8,
The scheduler calculates a signal-to-interference noise ratio of a mobile communication terminal to which a corresponding channel is assigned to each of the candidate members of the combination determined for each channel to obtain a maximum value, and then the maximum value exceeds the first threshold value. The distance between the first terminal pair having the maximum value and each of the candidate members except the first terminal pair among the candidate members of the combination determined for the corresponding channel is calculated, and the calculated distances are all the third threshold value. When exceeding, the resource scheduling apparatus for direct communication between the terminal, characterized in that for allocating the channel to the first terminal pair.

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