KR20200027348A - Method for allocating frequency in realtime communication of cellular device to device network - Google Patents

Abstract

Disclosed is a frequency resource allocation method for real-time communication in a cellular device-to-device (D2D) network. According to the present invention, the frequency resource allocation method in a D2D network may comprise the steps of: generating a combination of a cellular terminal and a D2D terminal pair for sharing a frequency resource allocated between a base station and at least one cellular terminal, for a plurality of cellular terminals and a plurality of D2D terminal pairs belonging to the base station; and determining a cellular terminal and a D2D terminal pair to share the frequency resource based on a required band of each combination, while supporting a preset predetermined data rate, for the generated combination.

Description

Frequency resource allocation method for real-time communication in a cellular D2D network {METHOD FOR ALLOCATING FREQUENCY IN REALTIME COMMUNICATION OF CELLULAR DEVICE TO DEVICE NETWORK}

Embodiments of the present invention relate to a frequency resource allocation technology for real-time communication in a cellular device to device (D2D) network.

D2D technology refers to a technology that directly communicates with mobile devices that are located at close range to a mobile device. In 5G mobile communication, D2D technology refers to a technology in which terminals (ie, D2D terminals) that implement cellular and Internet of Things (IoT) networking directly communicate.

As described above, in real-time communication in a network including a D2D terminal and a cellular terminal, the data rate is limited so that the cellular terminal and the D2D terminal maintain a constant data rate. CBR and GBR exist as techniques to limit the data rate.

CBR (Constant Bit Rate) is a bandwidth allocation technology that supports a fixed bit rate, and is a technique of constantly transmitting data at a fixed bit rate preset to a user terminal. GBR (Guaranteed Bit Rate) is a bandwidth allocation technology that guarantees a constant bit rate.

In a communication environment where data rates are limited, such as CBR and GBR, interference occurs when frequency resources are shared between a cellular terminal belonging to a base station and a D2D terminal forming the Internet of Things, and thus more CBR and GBR are guaranteed. Frequency resources are required.

Accordingly, there is a need for a technique for efficiently allocating frequency resources in a network environment in which cellular terminals and D2D terminals coexist and communicate.

Korean Registered Patent No. 10-1646433 searches a candidate terminal based on location information and transmission rate information of a plurality of terminals in a cell, divides the group into a cellular group and a D2D group according to the location information of the candidate terminal, and groups the location of each group. Disclosed is a location-based frequency resource allocation technique of a D2D communication system that matches a cellular group and a D2D group on the basis and shares frequency resources using an arrangement order of a candidate terminal of a cellular group and a candidate terminal of a D2D group.

The present invention is a technique for allocating frequency resources between a cellular terminal (Device UE) and a device to device (D2D) terminal in a network environment that provides a service that guarantees / supports a certain data rate, such as CBR or GBR. It is about.

In a method for allocating frequency resources in a cellular device to device (D2D) network, a plurality of cellular terminals belonging to a base station and a plurality of D2D terminal pairs are targeted to share the allocated frequency resource between the base station and at least one cellular terminal. Generating a combination of a cellular terminal and a D2D terminal pair, and targeting the generated combination, to support a predetermined predetermined data rate, and to share the frequency resource based on a required band of each combination And determining a pair of cellular terminals and D2D terminals.

According to one aspect, the step of determining a cellular terminal and a D2D terminal pair to share the frequency resource is based on the combination of the smallest required band among the combination, the cellular terminal and the D2D terminal pair (ie, CU-DU pair) ).

According to another aspect, in the generating of the combination, a plurality of cellular terminals belonging to the base station and a pair of D2D terminals belonging to the base station are paired with a pair of D2D terminals to share the frequency resource with a specific cellular terminal. You can create a set of

According to another aspect, the step of determining a pair of a cellular terminal and a D2D terminal to share the frequency resource, targeting a specific combination of the generated combinations, any one of a plurality of cellular terminals belonging to the base station And determining a D2D pair corresponding to a minimum required band based on the selected cellular terminal.

According to another aspect, the step of determining a cellular terminal and a D2D terminal pair to share the frequency resource is targeted to a specific combination among the generated combinations, and a specific D2D terminal pair among a plurality of D2D terminal pairs belonging to the base station And selecting a D2D pair corresponding to a minimum required band based on the selected D2D terminal pair.

According to another aspect, the step of determining the cellular terminal and the D2D terminal pair to share the frequency resource, targeting the generated combination, the minimum requirement among all the pairs generated to determine the cellular terminal and the D2D terminal pair You can decide which pair has the band.

According to another aspect, the request band may indicate a relatively larger band among the request band of the cellular terminal and the request band of the D2D terminal to share the frequency resource.

In a frequency resource allocation system in a cellular device to device (D2D) network, a plurality of cellular terminals belonging to a base station and a plurality of D2D terminal pairs are targeted to share the allocated frequency resource between the base station and at least one cellular terminal. A combination generating unit that generates a combination of a cellular terminal and a D2D terminal pair, and supports a predetermined predetermined data rate for the generated combination, but shares the frequency resource based on a required band of each combination It may include a determination unit for determining the cellular terminal and D2D terminal pair to be desired.

The present invention, in a network environment that provides a service that guarantees / supports a certain data rate, such as CBR or GBR, provides a method for allocating a frequency resource sharing between a cellular UE and a device to device (D2D) terminal. By presenting, it is possible to increase efficiency of frequency resources and reduce computational complexity relative to full search.

1 shows a network environment including a cellular terminal and a D2D terminal in an embodiment of the present invention.
2 is a flowchart illustrating a method for allocating frequency resources in a cellular D1D network in an embodiment of the present invention.
3 is a block diagram showing an internal configuration of a frequency resource allocation system in an embodiment of the present invention.
4 is a diagram illustrating a structure for finding a combination having a minimum required band under conditions that satisfy a certain data rate in an embodiment of the present invention.
5 is, in one embodiment of the present invention, a network structure provided to explain the required bandwidth calculation when sharing (sharing) resources.
6 is a graph showing complexity according to the number of terminals in an embodiment of the present invention.
7 is a graph showing the size of a requested bandwidth according to the number of terminals in an embodiment of the present invention.

The present embodiments relate to a frequency resource allocation technique for real-time communication in a cellular D2D network, and in particular, the cellular terminal and the D2D terminal pair under a condition that supports (ie satisfies) a predetermined predetermined data rate. It relates to a technique for sharing a frequency resource by determining a combination having a required band. That is, the present invention relates to a technique for sharing frequency resources in consideration of all characteristics of effectively using a bandwidth according to sharing of frequency resources and interference that may occur between a D2D terminal and a cellular terminal as the frequency resources are shared.

In the present embodiments, the 'cellular terminal (Cellular User Equipment)' refers to user terminals belonging to a base station, for example, a smartphone (smartphone), tablet (tablet), wearable device (wearable) located in the coverage (coverage) of the base station device), a laptop, a 2G / 3G terminal, and the like.

In the present embodiments, the 'D2D terminal' refers to an electronic device capable of direct communication, and for example, an electronic device forming an Internet of Things (IoT) network. That is, it can represent an electronic device capable of directly transmitting and receiving data between terminals without going through a base station.

In the present embodiments, the 'frequency resource allocation system' may correspond to a base station, or may correspond to a cellular terminal or a D2D terminal belonging to the base station.

1 shows a network environment including a cellular terminal and a D2D terminal in an embodiment of the present invention.

According to FIG. 1, the network 100 may include a user terminal (ie, a cellular terminal, 102) belonging to the base station 101, a D2D terminal pair A 110, and a D2D terminal pair B 120.

The frequency resources allocated for communication between the base station 101 and the cellular terminal 102 may be shared with the D2D terminal pair A 110 or may be shared with the D2D terminal pair B 120.

At this time, the transmitting D2D terminal 121 and the receiving D2D terminal 122 belonging to the D2D terminal pair B 120 are close to a predetermined interference distance between the base station 101 and the cellular terminal 102, and the D2D terminal pair A 110 The transmitting D2D terminal 111 and the receiving D2D terminal 112 belonging to the base station 101 and the cellular terminal 102 may be larger than a predetermined sharing distance, that is, located farther. In other words, when the frequency resource allocated for communication between the base station 101 and the cellular terminal 102 is shared with the D2D terminal pair B 120, interference occurs, so communication using individual frequency resources is a constant data rate. The condition can be satisfied. When the frequency resource allocated for communication between the base station 101 and the cellular terminal 102 is shared with the D2D terminal pair A 110, bandwidth can be saved by using the same frequency resource while satisfying a certain data rate.

Accordingly, the frequency resource allocation system is an environment in which N cellular terminals (CU) and M D2D terminal pairs (ie, transmitting D2D terminals and receiving D2D terminal pairs) are located in a cell covered by a base station. In some cases, frequency resources may be allocated by determining an effective combination of frequency resources.

2 is a flowchart illustrating a method for allocating frequency resources in a cellular D1D network in an embodiment of the present invention, and FIG. 3 is a block diagram illustrating an internal configuration of a system for allocating frequency resources in an embodiment of the present invention. It is.

Referring to FIG. 3, the frequency resource allocation system 300 may include a combination generation unit 310 and a determination unit 320, and each of the steps (steps 210 to 220) of FIG. 2 is illustrated in FIG. 3 It may be performed by the combination generating unit 310 and the determining unit 320, which are components of the frequency resource allocation system 300.

First, in FIGS. 2 and 3, it is assumed that N = M in a network environment in which N cellular terminals (CU) and M D2D terminal pairs (ie, transmitting D2D terminals and receiving D2D terminal pairs) are located in a cell. I will do it.

In step 210, the combination generator 310 targets a plurality of cellular terminals and a plurality of D2D terminal pairs (that is, a transmitting D2D terminal and a receiving D2D terminal corresponding to the D2D terminal pair) belonging to the base station, and at least one of the base station and the base station. A combination of a cellular terminal and a D2D terminal pair that wants to share allocated frequency resources between cellular terminals can be generated.

At this time, the combination generating unit 310 targets a plurality of cellular terminals belonging to the base station and D2D terminals belonging to the base station (ie, a transmitting D2D terminal and a receiving D2D terminal corresponding to a pair of D2D terminals), and a specific cellular terminal and frequency resources. A set of D2D terminal pairs to be shared can be generated.

In step 220, the determination unit 320 targets the generated combination, and supports a predetermined constant data rate (data rate), a pair of cellular and D2D terminals that want to share frequency resources based on the required band of each combination Can decide. In this case, the determination unit 320 may determine the cellular terminal and the D2D terminal pair based on the combination having the smallest required band among the generated combinations.

For example, the determination unit 320 may select a cellular terminal from among a plurality of cellular terminals belonging to a base station, for a specific combination among the generated combinations. Then, the determination unit 320 may determine the D2D pair corresponding to the minimum required band based on the selected cellular terminal. That is, the determination unit 320 may first randomly select any cellular terminal, and then determine a D2D pair having a minimum required band based on the selected cellular terminal.

As another example, the determination unit 320 may select a specific D2D terminal pair among a plurality of D2D terminal pairs belonging to a base station, for a specific combination among the generated combinations. Then, the determination unit 320 may determine a D2D pair corresponding to the minimum required band based on the selected D2D terminal pair. That is, the determination unit 320 may first select any D2D terminal pair randomly (random), and then determine the cellular terminal having the minimum required band based on the selected D2D terminal pair.

As another example, the determination unit 320 may determine a pair having a minimum required band among all pairs generated to determine a pair of cellular terminals and D2D terminals, based on the generated combination. In addition, a full search method may be used.

4 is a diagram illustrating a structure for finding a combination having a minimum required band under conditions that satisfy a certain data rate in an embodiment of the present invention.

In a network environment in which N cellular terminals (CU) and M D2D terminal pairs (ie, transmitting D2D terminals and receiving D2D terminal pairs) are located in a cell covered by a base station, when N = M For all cellular terminals (CU) and D2D terminal pairs (ie, transmitting and receiving D2D terminals), a set of combinations P to be paired with each other (ie, a pair of CU and transmitting and receiving D2D terminals) is represented by Equation 1 below. It can be expressed as

[Equation 1]

는

의 셀룰러 단말(CU)과 D2D 단말 쌍 간에 서로 쌍(pair, 즉, CU-DU 쌍)을 맺을지 여부를 나타내는 지시자의 조합에 해당할 수 있다. 예컨대,

이면

일 수 있다. 그리고,

의 엘리먼트(element)인

는 k번째 조합에서 셀룰러 단말(CU) n과 D2D 단말 쌍 m이 쌍(pair)의 결정 지시자(즉, index)를 나타낼 수 있다. 즉, k번째 조합에 속하는 셀룰러 단말(CU) n과 D2D 단말 쌍 m이 쌍(pair)을 맺을지 여부를 나타내는 지시자를 나타낼 수 있다. 이때,

중 모든 셀룰러 단말(CU)과 D2D 쌍(pair)이 미리 지정된 일정 데이터 레이트 R_T를 만족(즉, 지원)하는 조건에서의 최소 요구 대역을 갖는 조합은 아래의 수학식 2에 기초하여 결정될 수 있다.In Equation 1, P may denote a set of decision combinations to be paired with a plurality of cellular terminals (CU) and a plurality of D2D terminal pairs in a network. here,

Is

It may correspond to a combination of indicators indicating whether to pair each other (ie, a CU-DU pair) between a cellular terminal (CU) and a D2D terminal pair. for example,

Back side

Can be And,

Element of

In the k-th combination, the cellular terminal (CU) n and the D2D terminal pair m may indicate a pair of decision indicators (that is, index). That is, the cellular terminal (CU) n and D2D terminal pair m belonging to the k-th combination may indicate an indicator indicating whether to make a pair. At this time,

Among all, a combination having a minimum required band in a condition that all cellular terminals (CU) and D2D pairs satisfy (ie, support) a predetermined predetermined data rate R _T may be determined based on Equation 2 below. .

[Equation 2]

는 k번째 조합에서 셀룰러 단말(CU) n과 D2D 단말 쌍 m이 쌍(pair)의 결정 지시자(즉, index)를 나타낼 수 있다. 예컨대,

가 1이면 쌍(pair)을 맺는 것을 나타내고, 0이면 쌍(pair)을 맺지 않음을 나타낼 수 있다. CU와 D2D 단말 쌍 간에 쌍(pair)을 맺는 경우, 주파수 자원이 공유될 수도 있고, 별개의 자원이 할당될 수 있다. 여기서,1은 CU와 D2D 단말 쌍이 쌍(pair)을 맺음(pairing)을 나타내고, 0은 CU와 D2D 단말 쌍이 쌍을 맺지 않음(non pairing)을 나타낼 수 있다.In Equation 2,

In the k-th combination, the cellular terminal (CU) n and the D2D terminal pair m may indicate a pair determination indicator (that is, index). for example,

When 1 is 1, it indicates that a pair is formed, and when 0, a pair is not formed. When a pair is paired between a CU and a D2D terminal pair, frequency resources may be shared or separate resources may be allocated. Here, 1 may indicate that a pair of a CU and a D2D terminal pair (pairing), and 0 may indicate that a pair of a CU and a D2D terminal pair (non pairing).

은 셀룰러 단말(CU) n과 D2D 단말 쌍 m의 전송에 필요한 대역, 즉, 요구 대역을 나타낼 수 있으며, 자원 공유 여부를 포함할 수 있다. 이때, 상대적으로 더 작은 요구 대역의 자원 공유 방식이 이용될 수 있다. 예컨대, 주파수 자원 공유(sharing) 및 주파수 자원 비공유(non sharing) 중 상대적으로 더 작은 요구 대역에 해당하는 셀룰러 단말(CU) n과 D2D 단말 쌍 m이 결정될 수 있다.Again in Equation 2,

May indicate a band required for transmission of the cellular terminal (CU) n and a D2D terminal pair m, that is, a required band, and may include sharing of resources. At this time, a resource sharing scheme of a relatively smaller required band may be used. For example, a cellular terminal (CU) n and a D2D terminal pair m corresponding to a relatively smaller required band among frequency resource sharing and non-frequency resource sharing may be determined.

Referring to FIG. 4, it can be seen that in a real-time communication service requiring a fixed data rate (bps), when the frequency resource is shared, the size of the required band is reduced and the frequency efficiency is increased than when the resource is not shared. And, in the case of full search, as the number of terminals (cellular terminal and D2D terminal pair) increases, the computational complexity of determining the combination of the cellular terminal (CU) and the D2D terminal pair and determining whether to share resources increases. Able to know. Accordingly, the determination unit 320 may allocate frequency resources through a comparison of sums of required bands to satisfy a predetermined data rate (that is, a requested data rate). In other words, the pair with the smallest required band can be found. To this end, the sum of the required bands may be compared based on the objective function expressed as Equation 3 below.

[Equation 3]

은 아래의 수학식 4와 같이 표현될 수 있다.In Equation 3, the required band

Can be expressed as Equation 4 below.

[Equation 4]

According to Equation 4, when frequency resources are shared (that is, when a pair of a CU and a D2D terminal pair corresponds to sharing to share a resource) and when a frequency resource is not shared (that is, a CU and a D2D terminal) A relatively smaller band among the request bands of a pair that is paired but does not share resources) may be determined as a request band to be used in the objective function of Equation (3).

는 CU n과 D2D 단말 쌍 m이 자원 비공유(non sharing) 시 요구 대역을 나타내고,

는 CU n과 D2D 단말 쌍 m이 자원 공유(sharing) 시의 요구 대역을 나타낼 수 있다.In Equation 4,

Denotes a request band when CU n and D2D terminal pair m are non-shared,

May indicate a request band when resource pair sharing is performed by CU n and D2D terminal pair m.

5 is, in one embodiment of the present invention, a network structure provided to explain the required bandwidth calculation when sharing (sharing) resources.

Referring to FIG. 5, when a cellular terminal 502 belonging to a base station 501 and a pair of D2D terminals adjacent to the base station 510 and the cellular terminal 502 share frequency resources, interference with each other works In the case of, the signal-to-interference-plus-noise ratio (SINR) at the cellular terminal (CU) n may be expressed as Equation 5 below. In addition, SINR in the D2D terminal pair m may be expressed as Equation 6 below.

[Equation 5]

는 셀룰러 단말(CU) n의 전송 전력을 나타내는 것으로서,

으로 표현되고,

는 셀룰러 단말(CU) n과 기지국 사이의 채널 이득(channel gain)을 나타낼 수 있다.

는 수신기에서 목표 수신 전력의 세기를 나타내고,

는 잡음 전력을 나타낼 수 있다. 여기서, 수신기는 CU 입장에서는 기지국인 BS를 나타내고, D2D 단말 입장에서는 D2D 단말 m(즉, DR m)을 나타낼 수 있다.

는 송신 D2D 단말(즉, DT) m의 송신 전력을 나타내는 것으로서,

으로 표현될 수 있다.

는 기지국이 수신하는 송신 D2D 단말(DT) m으로 부터의 간섭 세기를 나타낼 수 있다.

는 송신 D2D 단말(즉, DT) m과 기지국 사이의 채널 이득(channel gain)을 나타낼 수 있다.In Equation 5,

Denotes the transmission power of the cellular terminal (CU) n,

Is expressed as,

May represent a channel gain between the cellular terminal (CU) n and the base station.

Denotes the strength of the target received power at the receiver,

Can represent noise power. Here, the receiver may indicate a BS as a base station in the CU position, and may indicate a D2D terminal m (ie, DR m) in the D2D terminal position.

Denotes the transmit power of the transmitting D2D terminal (ie, DT) m,

It can be expressed as.

May indicate the interference strength from the transmitting D2D terminal (DT) m received by the base station.

Denotes a channel gain between a transmitting D2D terminal (ie, DT) m and a base station.

[Equation 6]

는 송신 D2D 단말 m(즉, DT m)과 수신 D2D 단말 m(즉, DR m) 사이의 채널 이득을 나타내고,

는 셀룰러 단말(CU) n과 수신 D2D 단말 m(즉, DR m) 사이의 채널 이득을 나타낼 수 있다. 그리고,

는 수신 D2D 단말 m(즉, DR m)이 수신하는 셀룰러 단말(CU) n으로부터의 간섭의 세기를 나타낼 수 있다.In Equation 6,

Denotes the channel gain between the transmitting D2D terminal m (ie, DT m) and the receiving D2D terminal m (ie, DR m),

Denotes a channel gain between the cellular terminal (CU) n and the receiving D2D terminal m (ie, DR m). And,

Denotes the intensity of interference from the cellular terminal (CU) n received by the receiving D2D terminal m (ie, DR m).

In the network environment as shown in FIG. 5, a cellular terminal 502 belonging to a base station 501 and a pair of adjacent D2D terminals 503 and 504 adjacent to the base station 510 and the cellular terminal 502 share frequency resources. When interference is applied, channel capacity (bps / Hz) in the cellular terminal (CU) n and the D2D terminal pair m may be expressed as Equation 7 below.

[Equation 7]

는 셀룰러 단말(CU) n에서의 채널 캐패시티를 나타내고,

는 D2D 단말 쌍 m에서의 채널 캐패시티를 나타낼 수 있다.In Equation 7,

Denotes channel capacity at cellular terminal (CU) n,

Denotes channel capacity in the D2D terminal pair m.

은 아래의 수학식 8 및 9에 기초하여 계산될 수 있다. 즉, 위의 수학식 7을 기반으로 계산된 캐패시티를 통해 요구 전송 속도

를 만족시키기 위해 필요한 대역의 크기가 아래의 수학식 8 및 9에 기초하여 계산될 수 있다.In the network environment as shown in FIG. 5, when a cellular terminal 502 belonging to a base station 501 and a pair of D2D terminals 503 and 504 adjacent to the base station 510 and the cellular terminal 502 share frequency resources Required band

Can be calculated based on Equations 8 and 9 below. That is, the requested transmission rate through the capacity calculated based on the above equation (7)

The size of the band required to satisfy is can be calculated based on Equations 8 and 9 below.

Equation 8 below may indicate a request band of the cellular terminal (CU) n, and Equation 9 may indicate a request band of the D2D terminal pair m.

[Equation 8]

 [Equation 9]

는 미리 지정된 요구 전송 속도를 나타내고,

는 셀룰러 단말(CU) n과 D2D 단말 쌍 m이 자원을 공유 할 때의 셀룰러 단말(CU) n의 캐패시티(capacity)를 나타낼 수 있다.

는 셀룰러 단말(CU) n과 D2D 단말 쌍 m이 자원을 공유 할 때의 D2D 단말 쌍 m의 캐패시티(capacity)를 나타낼 수 있다.In Equation 8 and Equation 9,

Denotes a pre-specified request transmission rate,

Denotes the capacity of cellular terminal (CU) n when a pair of cellular terminals (CU) n and a D2D terminal pair m share resources.

Denotes the capacity of the D2D terminal pair m when the cellular terminal (CU) n and the D2D terminal pair m share resources.

은 각 단말의 요구 대역 중 상대적으로 더 큰 대역이 요구 대역으로서 결정될 수 있다. 즉, 주파수 자원 공유 시 CU 및 D2D 단말 쌍 중 요구 대역이 더 큰 대역이 자원 공유를 위한 요구 대역으로 결정될 수 있으며(

), 결정된 상기 더 큰 대역이 요구 대역으로 할당됨으로써, CU 및 D2D 단말 쌍의 요구 데이터 레이트가 모두 만족되도록 할 수 있다. At this time, when sharing resources, that is, the cellular terminal 502 belonging to the base station 501, and the base station 510 and the pair of D2D terminals adjacent to the cellular terminal 502 (503, 504) share the frequency resource ( sharing), the required band

The relatively larger band among the request bands of each terminal may be determined as the request band. That is, when a frequency resource is shared, a band having a larger requested band among CU and D2D UE pairs may be determined as a required band for resource sharing (

), The determined larger band is allocated as a required band, so that both the CU and D2D terminal pair request data rates are satisfied.

In the network environment as shown in FIG. 5, a required band in the case of non-sharing frequency resources may also be calculated. To this end, SINR and channel capacity at the time of no resource sharing may be first calculated based on Equations 10 and 11 below.

[Equation 10]

은 기지국이 셀룰러 단말(CU) n으로부터 수신하는 신호의 세기를 나타낼 수 있다. 여기서, 셀룰러 단말(CU) n의 전송 전력은

와 같이 표현될 수 있다.

은 수신 D2D 단말 m(DR m)이 송신 D2D 단말 m(DT m)으로부터 수신하는 신호의 세기를 나타내고,

는 미리 지정된 목표 수신 SNR을 나타낼 수 있다. 그리고, 송신 D2D 단말 m(DT m)에서의 전송 전력은

에 기초하여 결정될 수 있다.Equation 10 represents SINR when there is no interference between the cellular terminal (CU) n and the D2D terminal pair m because they do not share resources,

May indicate the strength of a signal that the base station receives from the cellular terminal (CU) n. Here, the transmission power of the cellular terminal (CU) n

It can be expressed as

Denotes the strength of the signal received by the receiving D2D terminal m (DR m) from the transmitting D2D terminal m (DT m),

May indicate a predetermined target reception SNR. And, the transmission power in the transmitting D2D terminal m (DT m)

It can be determined based on.

[Equation 11]

는 셀룰러 단말(CU) n에서의 채널 캐패시티,

는 D2D 단말 쌍 m에서의 채널 캐패시티를 나타낼 수 있다. Equation 11 shows the channel capacity (bps / Hz) when there is no interference between the cellular terminal (CU) n and the D2D terminal pair m because they do not share resources,

Is the channel capacity in the cellular terminal (CU) n,

Denotes channel capacity in the D2D terminal pair m.

은 아래의 수학식 12에 기초하여 계산될 수 있다.As such, the required bandwidth when non-sharing resources

Can be calculated based on Equation 12 below.

[Equation 12]

과

는 아래의 수학식 13에 기초하여 계산될 수 있다.In Equation 12,

and

Can be calculated based on Equation 13 below.

[Equation 13]

는 미리 지정된 요구 전송 속도를 나타내고,

은 요구 전송 속도

를 만족시키기 위해 필요한 셀룰러 단말(CU) n에서의 대역의 크기,

는

를 만족시키기 위해 필요한 D2D 단말 쌍 m에서의 대역의 크기를 나타낼 수 있다.In Equation 13,

Denotes a pre-specified request transmission rate,

Required transfer rate

The size of the band in the cellular terminal (CU) n required to satisfy the,

Is

It may indicate the size of the band in the D2D terminal pair m required to satisfy the.

이 계산될 수 있다. 즉, 자원을 공유하지 않음에 따라, 셀룰러 단말(CU) n을 위한 요구 대역 및 D2D 단말 쌍 m)을 위한 요구 대역이 개별적으로 할당되어야 하므로, 각 단말의 요구 대역의 합으로, 요구 대역

이 계산될 수 있다.According to Equation 12, when the resource is non-shared (non sharing), as a sum of the request bands of each terminal (cellular terminal (CU) n and D2D terminal pair m), the request band

Can be calculated. That is, as the resource is not shared, the request band for the cellular terminal (CU) n and the request band for the D2D terminal pair m) must be individually allocated, so as a sum of the request bands of each terminal, the request band

Can be calculated.

6 is a graph showing complexity according to the number of terminals in an embodiment of the present invention, and FIG. 7 is a graph showing a size of a requested bandwidth according to the number of terminals in an embodiment of the present invention.

The simulation environment of FIGS. 6 and 7 may be as shown in Table 1 below. In addition, N represents the number of cellular terminals (CU), M represents the number of D2D terminal pairs, and may correspond to N = M = [2: 2: 10]. And, it can be assumed that the terminals are uniformly distributed in a cell.

Referring to Figure 6, full search (full search) is an optimal solution technique, a request band based on a pair (ie, CU-DU pair) decision matrix of a cellular terminal and a transmit / receive D2D terminal in which the sum of request bands is minimum. As it is determined by comparing the sum of, it can be confirmed that the algorithm complexity increases rapidly as the number of terminals increases. That is, it can be confirmed that the complexity increases to NХN !. Selection 1 is to first determine a pair (that is, a pair of CU-DUs) having a minimum required band based on a randomly selected cellular terminal (CU), The complexity may correspond to N (N + 1) / 2. That is, it can be confirmed that the complexity is relatively low even though the number of terminals increases compared to full search.

Selection 2 is to first determine a pair (pair, ie, a CU-DU pair) having a minimum required band based on a randomly selected D2D terminal pair. The complexity is N (N + 1) / 2, which is the same as Selection 1 You can.

Selection 3 indicates complexity according to an increase in the number of terminals when a pair having a minimum required band is first determined from a pair that can be generated (that is, a CU-DU pair), and the complexity is N (N + 1) (2N + 1) / 6. That is, although the complexity of selection 3 is relatively higher than that of selection 1 and selection 2 as the number of terminals increases, as shown in FIG. 7, it can be confirmed that as the number of terminals increases, it has a relatively smaller resource allocation than selection 1 and selection 2. have.

In FIG. 7, selections 1 to 3 and full search are the same as in FIG. 6, and non sharing may indicate a case of not sharing a resource.

FIG. 7 shows a comparison of an average of resource allocation per terminal when five resource allocation methods are applied, and according to FIG. 7, the resource demand decreases when resources are shared than when resource sharing is not performed. , It can be seen that the corresponding reduction amount increases as the number of users (ie, the number of terminals) increases. As a result, it can be seen that the frequency efficiency increases. As described above, it can be confirmed that the average of the required bands varies depending on how the CU-DU pair is selected, and it can be confirmed that although selection 1 to 3 have lower complexity than full search, frequency efficiency similar to that of full search is obtained. For example, in the case of selection 3, it can be seen that the average performance of the required band compared to full search is slightly different at about 2%.

Meanwhile, in FIG. 6, the complexity calculation criterion may be set as a sum of the number of pairs to be calculated when selecting a CU-DU pair.

For example, when N = 2, 3,?, N, when selecting in order from cellular terminal 1 (CU 1) to cellular terminal 2 (CU2),?, Cellular terminal N (CU N), selection 1 and selection 2 In, the calculated complexity may be as shown in Table 2 below.

As another example, when N = 2, 3,?, N, when selecting in order from cellular terminal 1 (CU 1) to cellular terminal 2 (CU2),?, Cellular terminal N (CU N), calculation is performed in selection 3 The complexity can be as shown in Table 3 below. As shown in Table 3 below, Selection 3 can compare the required bands for all CU-DU pairs that can be generated for each selection when selecting a CU-DU pair.

Full search indicates a method of comparing the sum of required bands for all CU-DU pair combinations, and the complexity may be as shown in Table 4 below. Here, the combination of all CU-DU pairs may be the same as the number ( _N P _N ) in the case of a method of counting N people.

In Table 4 above, N represents the number of CU-DU pairs in one combination, and {N (N-1) (N-2) ... 1} may represent the number of possible combinations.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiments or may be known and usable by those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and magnetic media such as floptical disks. -Hardware devices specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine language codes produced by a compiler.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques are performed in a different order than the described method, and / or the components of the described system, structure, device, circuit, etc. are combined or combined in a different form from the described method, or other components Alternatively, even if replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims (8)

In a method for allocating frequency resources in a cellular device to device (D2D) network,
Generating a combination of a cellular terminal and a D2D terminal pair for sharing a frequency resource allocated between a base station and at least one cellular terminal for a plurality of cellular terminals and a plurality of D2D terminal pairs belonging to a base station; And
Determining a pair of cellular terminals and D2D terminals that want to share the frequency resource based on a required band of each combination, while supporting a predetermined predetermined data rate for the generated combination.
Frequency resource allocation method comprising a. According to claim 1,
Determining the cellular terminal and the D2D terminal pair to share the frequency resource,
Determining the cellular terminal and the D2D terminal pair based on the combination with the smallest required band among the combinations
Frequency resource allocation method characterized in that. According to claim 1,
The step of generating the combination,
Generating a set of a combination of a pair of D2D terminals to share the frequency resource with a specific cellular terminal, for a plurality of cellular terminals belonging to the base station and a pair of D2D terminals belonging to the base station;
Frequency resource allocation method comprising a. According to claim 1,
Determining the cellular terminal and the D2D terminal pair to share the frequency resource,
Selecting a cellular terminal among a plurality of cellular terminals belonging to the base station, for a specific combination among the generated combinations; And
Determining a D2D pair corresponding to a minimum required band based on the selected cellular terminal
Frequency resource allocation method comprising a. According to claim 1,
Determining the cellular terminal and the D2D terminal pair to share the frequency resource,
Selecting a specific D2D terminal pair among a plurality of D2D terminal pairs belonging to the base station for a specific combination among the generated combinations; And
Determining a D2D pair corresponding to a minimum required band based on the selected D2D terminal pair
Frequency resource allocation method comprising a. According to claim 1,
Determining the cellular terminal and the D2D terminal pair to share the frequency resource,
Based on the generated combination, determining a pair having a minimum required band among all pairs generated to determine a cellular terminal and a D2D terminal pair
Frequency resource allocation method characterized in that. According to claim 1,
The request band indicates a relatively larger band among the request band of the cellular terminal and the request band of the D2D terminal to share the frequency resource
Frequency resource allocation method characterized in that. In the frequency resource allocation system in a cellular device to device (D2D) network,
A combination generator configured to generate a combination of a cellular terminal and a D2D terminal pair that want to share a frequency resource allocated between a base station and at least one cellular terminal for a plurality of cellular terminals and a plurality of D2D terminal pairs belonging to a base station; And
Determining unit for determining the pair of cellular terminals and D2D terminals that want to share the frequency resource based on the required band of each combination, while supporting a predetermined predetermined data rate for the generated combination.
Frequency resource allocation system comprising a.

Images