KR101215957B1 - Method and Apparatus for Allocating Sub-channels Using Dynamic Fractional Frequency Reuse Scheme - Google Patents

Abstract

The number of reused subchannels and the number of exclusive subchannels of each of the one or more first mobile nodes wirelessly connected with the first mobile base station, and one wirelessly connected with the second mobile base station causing intercell interference between the first mobile base station and the first mobile base station; Calculating the number of reused subchannels and the number of exclusive subchannels of each of the second mobile nodes, the number of reused subchannels and the number of exclusive subchannels of the one or more first mobile nodes, and the number of reused subchannels of the one or more second mobile nodes. Based on the number of channels and the number of exclusive subchannels, the at least one first mobile node and the at least one agent to minimize the total number of subchannels required by the at least one first mobile node and the at least one second mobile node. A method comprising assigning a subchannel to a mobile node is provided. In this case, when interference occurs between mobile base stations in a wireless communication network including a mobile base station and a mobile node, it is possible to increase frequency use efficiency while minimizing inter-cell interference by using a dynamic partial frequency use technique. It is possible to optimize the number of subchannels required for all mobile nodes while satisfying the required data rate.

Description

Subchannel Allocation Method and Apparatus Using Dynamic Partial Frequency Reuse Scheme {Method and Apparatus for Allocating Sub-channels Using Dynamic Fractional Frequency Reuse Scheme}

The present invention relates to a subchannel allocation method and apparatus using a dynamic partial frequency reuse technique. More specifically, the present invention provides a subchannel for each mobile node to minimize the number of subchannels required for all mobile nodes while satisfying the data rate required by the mobile node in a wireless communication network including the mobile base station and the mobile node. A method and apparatus for assigning.

In a wireless communication network, a given frequency resource may be allocated to each user with a predetermined bandwidth in order to provide multiple accesses for different users. For example, in a wireless communication system supporting multiple access, such as orthogonal frequency division multiple access (OFDMA), frequency resources of the system are allocated to each user in sub-channel units.

In such a wireless communication system, it is a cell where a base station (BS) allocates a subchannel using all of the channel bandwidths of the system to all mobile nodes (MNs) wirelessly connected to the base station. Although advantageous in terms of capacity, inter-cell interference may occur when the same channel is used in the same time zone by another base station adjacent to the base station. Therefore, it is necessary to maximize the frequency efficiency and increase the cell capacity while providing an appropriate signal to interference plus noise ratio (SINR) for the mobile node in the wireless communication network affected by the interference.

To this end, a frequency reuse scheme may be used as a method for mitigating co-channel interference that mobile nodes located at a cell boundary receive from a base station of an adjacent cell using the same communication band. . Conventional frequency reuse techniques include hard frequency reuse, fractional frequency reuse, and soft frequency reuse.

The hard frequency reuse scheme divides a predetermined frequency band into subbands according to a frequency reuse factor (FRF), and then allocates different subbands to adjacent base stations spaced apart by a predetermined distance or more. The partial frequency reuse scheme divides a predetermined frequency band into an inner band and an outer band, and then causes all base stations to reuse the inner band at a frequency reuse rate of 1 for a mobile node located in the center portion of the cell (ie, near the base station). For the mobile node located at the cell edge, the outer band is divided according to the frequency reuse rate, and each base station is allowed to reuse each part of the divided outer band. The soft frequency reuse scheme allows each base station to use the inner band for the mobile node located at the center of the cell and the outer band for the mobile node located at the edge of the cell, with each outer band being assigned to be orthogonal to each other. It has a higher transmit power than the internal band.

Unlike wireless communication networks utilizing a fixed infrastructure, wireless communication networks in which base stations are dynamically deployed without infrastructure, such as at least a data rate for a mobile node as the base station moves in response to the movement of the mobile node in the military sector. In a tactical network configured to provide wireless communication at a rate, a change in inter-cell interference may occur since the distance to a base station causing co-channel interference changes as any base station moves. However, the conventional frequency reuse technique is not suitable for increasing frequency use efficiency while minimizing inter-cell interference in an environment in which the location of a base station may change.

Accordingly, the present invention provides a dynamic partial frequency reuse scheme in which a mobile base station minimizes the number of subchannels required for all mobile nodes while satisfying the data rate required for each mobile node associated with the mobile base station in a network having the above characteristics. The purpose is to effectively mitigate co-channel interference and increase frequency efficiency.

In addition, another object of the present invention is to provide a dynamic partial frequency reuse scheme, in which the computational complexity required for allocating subchannels required to ensure at least a predetermined data rate for all mobile nodes with a limited frequency band is provided. To reduce the number of subchannels allocated.

The object of the present invention is not limited to the above-mentioned object, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention for achieving the above object, the number of reuse sub-channel and exclusive sub-channel of each of the one or more first mobile nodes wirelessly connected to the first mobile base station the number of dedicated subchannels and the number of reuse subchannels of each of the one or more second mobile nodes wirelessly connected with the second mobile base station causing inter-cell interference with the first mobile base station. Calculating a number, based on the number of reused subchannels and the number of exclusive subchannels of the at least one first mobile node and the number of reused subchannels and the number of exclusive subchannels of the at least one second mobile node, Wherein the one or more first transitions are minimized to minimize the total number of subchannels required by one mobile node and the one or more second mobile nodes. Allocating a subchannel to the node and the at least one second mobile node.

In addition, the subchannel allocating step may eliminate the use of subchannels or intercell interference for partial frequency reuse for each of the one or more first mobile nodes and each of the one or more second mobile nodes to optimize the total number of the subchannels. Determining the use of a subchannel for the method.

The determining may include determining that some of the one or more first mobile nodes use subchannels for partial frequency reuse based on the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes. And determining that some of the one or more second mobile nodes use subchannels for partial frequency reuse based on the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes. to provide.

The method may further include detecting whether the first mobile base station and the second mobile base station cause inter-cell interference with each other before the calculating step.

The method may further include obtaining first channel information for calculating the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes.

The method also includes receiving second channel information from the second mobile base station for calculating the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes.

According to another embodiment of the present invention for achieving the above object, the number of reused subchannels and the number of exclusive subchannels of each of the one or more first mobile nodes wirelessly connected to the first mobile base station, and the first mobile base station and A subchannel number calculator configured to calculate the number of reused subchannels and the number of exclusive subchannels of each of the one or more second mobile nodes wirelessly connected with the second mobile base station causing intercell interference between and the at least one first Based on the reuse subchannel number and the exclusive subchannel number of the mobile node and the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes, the at least one first mobile node and the at least one second mobile node. The at least one first mobile node and the downstream to minimize the total number of subchannels required by the An apparatus is provided that includes a subchannel allocator configured to assign a subchannel to one or more second mobile nodes.

In addition, the subchannel allocator may further eliminate the use of subchannels or intercell interference for partial frequency reuse for each of the one or more first mobile nodes and each of the one or more second mobile nodes to optimize the total number of subchannels. An apparatus is provided that is configured to determine the use of a subchannel for a channel.

Further, the subchannel allocator uses a subchannel for partial frequency reuse by some of the at least one first mobile node based on the reuse subchannel number and the exclusive subchannel number of the at least one first mobile node for the determination. And determine that some of the one or more second mobile nodes use subchannels for partial frequency reuse based on the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes. to provide.

The present invention also provides a device configured to detect whether the first mobile base station and the second mobile base station cause inter-cell interference with each other.

In addition, the apparatus further includes a channel information obtaining unit configured to obtain first channel information for calculating the reuse subchannel number and the exclusive subchannel number of the at least one first mobile node.

The channel information acquisition unit also provides an apparatus configured to receive second channel information from the second mobile base station for calculating the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes.

According to an embodiment of the present invention, when the location of the base station constituting the network can be dynamically changed, while increasing the frequency use efficiency while minimizing the inter-cell interference caused by the change of the distance between the base station causing co-channel interference, the mobile node There is an effect of optimizing the total number of subchannels allocated to each mobile node to provide the data rate required for each.

1 is a diagram illustrating an exemplary configuration of a wireless communication system in which subchannel allocation is performed according to an embodiment of the present invention.
2 illustrates an example of mapping a required number of subchannels on a frame to each mobile node to which a subchannel is allocated according to an embodiment of the present invention.
3 is a flowchart illustrating a process of allocating subchannels to satisfy a required data rate of all mobile nodes in a downlink of a wireless communication network according to an embodiment of the present invention.
4 is a diagram illustrating a process of allocating subchannels to mobile nodes when two mobile base stations cause co-channel interference in a wireless communication system according to an exemplary embodiment of the present invention.
5 is a diagram schematically illustrating a configuration of an apparatus for allocating subchannels according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the present invention and methods and systems for achieving the same can be more clearly understood with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various other forms. In other words, the following examples are merely provided for a sufficient disclosure of the present invention and are not intended to limit the scope of the present invention. Also, like reference numerals refer to like elements throughout.

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

1 is a diagram illustrating an exemplary configuration of a wireless communication system in which subchannel allocation is performed according to an embodiment of the present invention.

The wireless communication system 100 includes mobile base stations 120, 140 and mobile nodes 160, 170, 180. In the wireless communication system 100, the number of mobile base stations and the number of mobile nodes may be different from those shown in FIG. For example, the wireless communication system 100 may allocate frequency resources in sub-channel units to mobile nodes using OFDMA as a multiple access scheme.

In the wireless communication system 100, a communication channel and a control channel may be used. Here, the communication channel is used for transmitting and receiving user data between the mobile node and the mobile base station, and the control channel is used for exchanging various control information between the mobile node and the mobile base station or between the mobile base stations. In particular, the control channel can be used to send SINR information of mobile nodes to an associated mobile base station and can also be used for information exchange between mobile base stations that can interfere with each other. In order to maintain the reliability of information exchange through such a control channel, transmission on the control channel may be performed with sufficient power to be transferred between adjacent mobile base stations, and channel coding may be used separately or in addition thereto. Can be.

로 주어진다. 또한, 도 1에 도시된 바와 같이, 이동 기지국(120, 140)에 대하여 채널 재사용 거리(channel reuse distance)

가 정의될 수 있는데, 이동 기지국(120, 140) 간의 거리가 이 값보다 작아지면 본 발명의 실시예에 따른 서브채널 할당이 수행될 수 있다.For a mobile base station (120, 140) of the wireless communication system 100, a predetermined communication radius (radius of the cell) may be defined. Referring to FIG. 1, the communication radiuses of the mobile base stations 120 and 140 are all

. In addition, as shown in Figure 1, the channel reuse distance (channel reuse distance) for the mobile base station (120, 140)

If the distance between the mobile base station (120, 140) is smaller than this value, sub-channel allocation according to an embodiment of the present invention can be performed.

In one embodiment of the invention, the wireless communication system 100 may operate in a wireless communication network, such as a tactical communication network, configured without a fixed infrastructure. For example, mobile base stations 120 and 140 may be configured to support communication only for mobile nodes belonging to the same unit, respectively. Referring to FIG. 1, the mobile base station 120 and the mobile nodes 160 and 170 may belong to the same unit. In such a case, the mobile node 160, 170 may not be allowed to handoff to the mobile base station 140 even if it is out of the communication radius of the mobile base station 120. This may be the same even when the mobile base station 140 and the mobile node 180 belong to the same unit. Furthermore, in the wireless communication system 100, the mobile base stations 120 and 140 may not be connected to the backbone network, which may result in, for example, the mobile base station 140 rather than the reception strength from the mobile base station 120 at the mobile node 160. Mobile node 160 may be configured not to handoff to another base mobile base station 140 even if the reception strength from the mobile station is large.

보다 작아지는 경우, 서로 간섭을 일으킬 수 있는 이동 기지국(120, 140) 간의 제어 채널이 활성화되어 서브채널 할당을 수행하는 데에 필요한 정보가 이동 기지국(120, 140) 간에 교환될 수 있다. 이때, 서브채널의 할당은 이동 기지국(120, 140) 중 조정 이동 기지국으로 선택된 이동 기지국에서 수행될 수 있다. 조정 이동 기지국의 선택은 이동 기지국(120, 140) 중에서 그 ID가 가장 낮은 것을 찾는 방식으로 이루어질 수 있다. 예컨대, 이동 기지국(120)이 조정 이동 기지국으로 선택되어 인접한 이동 기지국(140)으로부터 제어 채널을 통해 서브채널 할당을 수행하는 데 필요한 정보를 수집하고 이를 이용하여 서브채널 할당을 수행한 후, 그 결과를 인접 이동 기지국(140)에 전송할 수 있다.Meanwhile, referring to FIG. 1, the distance between the mobile base stations 120 and 140 is the channel reuse distance.

If smaller, the control channel between the mobile base stations 120 and 140, which may interfere with each other, is activated so that information necessary to perform subchannel allocation may be exchanged between the mobile base stations 120 and 140. In this case, subchannel allocation may be performed at a mobile base station selected as a coordinated mobile base station among mobile base stations 120 and 140. The selection of the coordinated mobile base station may be made by finding the lowest among the mobile base stations 120 and 140. For example, the mobile base station 120 is selected as the coordinating mobile base station to collect information necessary for performing subchannel allocation through the control channel from the adjacent mobile base station 140 and use the same to perform subchannel allocation, and as a result, May be transmitted to the neighboring mobile base station 140.

Depending on whether frequency reuse is allowed due to subchannel allocation, mobile nodes can be divided into two groups. One is a reuse group, which is a set of mobile nodes capable of using the same subchannel in cells associated with neighboring base stations 120 and 140 causing mutual interference, and a mobile node belonging to the reuse group is called a reuse node. . The other is an exclusive group, which is a set of mobile nodes that use subchannels used only in one of the cells associated with neighboring base stations 120 and 140 that cause mutual interference and belong to the mobile group. Is called an exclusive node.

In one embodiment of the present invention, the coordination mobile base station 120 requests for each mobile base station 120,140 wirelessly with that mobile base station, that is, if each mobile node belonging to the mobile base station belongs to a reuse group. The number of subchannels required to satisfy the data rate (hereinafter, referred to as the number of reused subchannels) and the number of subchannels required to satisfy the required data rate when the mobile node belongs to an exclusive group (hereinafter referred to as the number of exclusive subchannels). ), Each mobile node 160, 170, 180 to minimize the total number of subchannels (hereinafter, the total number of required subchannels) for satisfying the required data rate of all mobile nodes 160, 170, 180. ) Can be performed by subchannel allocation. This is a kind of dynamic partial frequency reuse.

Hereinafter, subchannel allocation according to an embodiment of the present invention will be described in more detail.

번째 이동 기지국에 속한

번째 이동 노드의 재사용 서브채널 개수

및 독점 서브채널 개수

는

번째 이동 기지국과

번째 이동 노드 간의 채널 특성이나 인접하는

번째 이동 기지국에 따른 간섭의 영향에 기반하여 획득할 수 있다. 여기서,

와

는

번째 이동 기지국에서

번째 이동 노드에 할당되는 프레임 당 평균 서브채널의 개수로서 주어질 수 있다. First of all, in a wireless communication network that supports multiple connections such as OFDMA,

Belonging to the first mobile base station

Number of reuse subchannels in the first mobile node

And exclusive subchannels

The

With the first mobile base station

Channel characteristics between the first mobile node or

It can be obtained based on the influence of the interference according to the first mobile base station. here,

Wow

The

On the first mobile base station

It can be given as the average number of subchannels per frame allocated to the first mobile node.

와

를 획득한 후, 획득된

와

를 이용하여 전술한 서브채널 할당을 수행할 수 있다. 이로써, 각 이동 노드가 재사용 노드인지 또는 독점 노드인지 결정됨에 따라, 각 이동 노드 별로 필요한 서브채널의 개수(이하, 이동 노드의 서브채널 개수)가

또는

로 결정될 수 있다.Then, for all mobile nodes belonging to mobile base stations causing co-channel interference, the coordinated mobile base station is

Wow

After acquiring

Wow

The aforementioned subchannel allocation can be performed using. Accordingly, as it is determined whether each mobile node is a reuse node or an exclusive node, the number of subchannels required for each mobile node (hereinafter, referred to as the number of subchannels of the mobile node) is determined.

or

. ≪ / RTI >

와

의 값이 정수가 아니더라도

번째 이동 기지국에 속한

번째 이동 노드에 대하여 이동 노드의 서브채널 개수를

또는

으로 하지 않아도 무방하다는 것을 의미한다(여기서,

는

이상인 최소의 정수임).2 illustrates an example of mapping a required number of subchannels on a frame to each mobile node to which a subchannel is allocated according to an embodiment of the present invention. Referring to FIG. 2, when subchannel allocation is performed for each mobile node in consideration of only the downlink in the frame 200, the average number of subchannels allocated to the mobile node MN # 4 is 0.5. Instead of allocating subchannels, one subchannel may be used by 1/2. this is

Wow

Even if the value of is not an integer

Belonging to the first mobile base station

The number of subchannels of the mobile node with respect to the first mobile node

or

Means you don't have to

The

Minimum integer greater than or equal to).

3 is a flowchart illustrating a process of allocating subchannels to satisfy a required data rate of all mobile nodes in a downlink of a wireless communication network according to an embodiment of the present invention.

내에 근접한 이동 기지국이 있는지 감지한다(310).First of all, each mobile base station has a channel reuse distance from its location through the control channel.

If there is a mobile base station in proximity to the detected (310).

거리 내에 인접한 것으로 감지된 이동 기지국들이 존재하면, 그 이동 기지국들 중에서 조정 이동 기지국을 선택한다(320). 전술한 바와 같이, 조정 이동 기지국은

거리 내에 인접한 것으로 감지된 이동 기지국들의 ID를 비교함으로써 선택될 수 있다.

If there are mobile base stations detected as being within range, a coordinated mobile base station is selected from the mobile base stations (320). As mentioned above, the coordinated mobile base station

It may be selected by comparing the IDs of mobile base stations detected as being within range.

와

를 포함할 수 있다. 여기서,

는 서브캐리어(sub-carrier)

에 대해

번째 이동 기지국에 속한

번째 이동 노드의 채널 상수

의 분산 평균값이고,

는 인접한

번째 이동 기지국으로부터 서브캐리어

에 대해

번째 이동 기지국에 속한

번째 이동 노드의 채널 상수

의 분산 평균값이다.Each of the above mobile base stations (i.e., mobile base stations causing co-channel interference) receives information from all mobile nodes belonging to it, the channel characteristics between itself and the mobile node, and information about interference between adjacent mobile base stations and the mobile node. Collecting channel information to be included (330). For example, in an OFDMA wireless communication network, the above channel information is

Wow

. ≪ / RTI > here,

Is a sub-carrier

About

Belonging to the first mobile base station

Channel constant of the first mobile node

Is the mean of the variance of

Is adjacent

Subcarrier from the first mobile base station

About

Belonging to the first mobile base station

Channel constant of the first mobile node

Is the mean of variance.

The selected coordinating mobile base station collects the above channel information from neighboring mobile base stations causing co-channel interference (340).

와

를 계산하고, 이를 이용하여 각 이동 노드에 대한 서브채널 할당(모든 이동 노드들의 요구 데이터 레이트를 만족시키기 위한 서브채널의 총 개수, 즉 요구 서브채널 총 개수를 최소화하도록 각 이동 노드들을 재사용 노드 또는 독점 노드로 결정함)을 수행한다(350).Thereafter, once the transmission powers of the above mobile base stations are allocated to a predetermined value, the coordinating mobile base station uses the above channel information for all mobile nodes.

Wow

Calculate the sub-channel allocation for each mobile node (reuse node or exclusive to reuse each mobile node to minimize the total number of subchannels to satisfy the required data rate of all mobile nodes, i.e. the total number of required subchannels). Determine node) (350).

와

을 다시 계산하고 각 이동 노드에 대한 서브채널 할당을 다시 수행하는 일련의 과정을, 요구 서브채널의 총 개수가 이용가능한 서브채널의 총 개수를 초과하지 않는다고 판정할 수 있을 때까지 반복함으로써 이동 기지국들의 송신 전력을 할당할 수 있다.If the total number of required subchannels minimized according to the subchannel allocation is greater than the total number of available subchannels, it can be seen that the mobile base stations are severely subjected to the same channel interference, and adjust the transmission power of the mobile base stations ( 360). At this time, the transmission powers of the mobile base stations are allocated such that the sum of the transmission powers of the mobile base stations is minimum while the total number of required subchannels does not exceed the total number of available subchannels. In this case, the transmission power allocation of the mobile base stations may be performed by determining an optimal value by an iterative process derived from the optimization algorithm. For example, in a coordinated mobile base station, after adjusting the transmit powers of the mobile base stations, all mobile nodes in accordance with such a change in transmit power.

Wow

Repeating the sequence of recalculating 하고 and performing subchannel allocation for each mobile node again until it can be determined that the total number of required subchannels does not exceed the total number of available subchannels. Transmit power can be allocated.

Hereinafter, a process of determining each mobile node as a reuse node or an exclusive node to minimize the total number of required subchannels will be described in detail.

4 is a diagram illustrating a process of allocating subchannels to mobile nodes when two mobile base stations cause co-channel interference in a wireless communication system according to an exemplary embodiment of the present invention.

(420)과 이동 기지국

(440)이 동일 채널 간섭을 야기하는 것으로 감지된 경우를 고려한다(도 4의 사선은 이러한 간섭의 영향을 나타냄). 우선, 각각의 이동 기지국(420, 440)은 자신에게 속한 모든 이동 노드로부터 채널 정보를 수집한다. 단, 여기서는 설명의 편의를 위해 각각의 이동 기지국(420, 440)에 속한 이동 노드의 수를 동일하게

으로 한다. 이어서, 조정 이동 기지국(420)은 다른 이동 기지국(440)이 수집한 채널 정보를 수신하고, 모든 이동 노드들에 대하여 재사용 서브채널 개수

(460a, 460b) 및 독점 서브채널 개수

(462a, 462b)를 계산한다.Mobile base station in wireless communication system 400

420 and mobile base station

Consider the case where 440 is detected to cause co-channel interference (the diagonal lines in FIG. 4 indicate the effect of this interference). First, each mobile base station 420, 440 collects channel information from all mobile nodes belonging to it. However, for the convenience of description, the number of mobile nodes belonging to each of the mobile base stations 420 and 440 is the same.

. Subsequently, the coordinated mobile base station 420 receives channel information collected by the other mobile base station 440, and reuses the number of subchannels for all mobile nodes.

(460a, 460b) and number of exclusive subchannels

462a and 462b are calculated.

Here, as shown in FIG. 4, the coordinated mobile base station 420 designates each mobile node belonging to it as a reuse node or an exclusive node, and likewise, designates each mobile node belonging to the mobile base station 440 as a reuse node or an exclusive node. Consider the case where At this point, no node can belong to both a reuse group and an exclusive group.

, 독점 서브채널의 개수(462a)의 합을

라 하고, 이동 기지국(440)에 속한 각 이동 노드에 대한 재사용 서브채널 개수(460b)의 합을

, 독점 서브채널의 개수(462b)의 합을

라 한다면, 무선 통신 시스템(400)에서 요구되는 전체 서브채널의 개수(즉, 요구 서브채널의 총 개수)는

와

중 큰 값에

와

를 합한 값이 된다. 도 4에 도시된 바와 같이, 만일

가

보다 큰 경우 요구 서브채널의 총 개수는

+

+

이 된다.The sum of the number of reuse subchannels 460a for each mobile node belonging to the mobile base station 420 is obtained.

, The sum of the number of exclusive subchannels 462a.

The sum of the number of reuse subchannels 460b for each mobile node belonging to the mobile base station 440

, The sum of the number of exclusive subchannels 462b.

In this case, the total number of subchannels required in the wireless communication system 400 (that is, the total number of required subchannels) is

Wow

To the greater of

Wow

Is the sum of. As shown in Figure 4, if

end

If greater than, the total number of required subchannels is

+

+

.

Accordingly, the coordinating mobile base station 420 may identify a case where the total number of required subchannels is minimized in each case where each mobile node belonging to the mobile node belonging to the mobile base station 440 is determined to be a reuse node or an exclusive node. By judging in a manner, subchannel allocation is performed. A brute-force search method may be used as the method for the above determination, and an optimization or suboptimal algorithm is used to reduce the complexity of the calculation that increases exponentially with the number of mobile base stations and the number of mobile nodes. Can also be used.

According to an embodiment of the present invention, a process of performing the subchannel allocation while reducing the complexity of the calculation will be described in detail as follows.

개의 이동 기지국이 동일 채널 간섭을 야기하는 경우를 고려한다. 다만, 설명의 편의를 위해, 각 이동 기지국에 속한 이동 노드의 수는 모두

으로 주어진다.For generalization,

Consider a case where two mobile base stations cause co-channel interference. However, for convenience of description, the number of mobile nodes belonging to each mobile base station is

.

번째 이동 기지국에 속한 임의의

번째 이동 노드의 재사용 서브채널 개수

및 독점 서브채널 개수

가 주어지면,

번째 이동 기지국에 속한 각 이동 노드에 대한 재사용 서브채널 개수의 합

과 독점 서브채널의 개수의 합

은 다음 수학식과 같이 표현될 수 있다.random

Belonging to the first mobile base station

Number of reuse subchannels in the first mobile node

And exclusive subchannels

Is given,

Sum of the number of reused subchannels for each mobile node belonging to the first mobile base station

Sum of the number of subchannels

Can be expressed as the following equation.

는

번째 이동 기지국에 속한

번째 이동 노드가 재사용 노드이면 1이고, 독점 노드이면 0으로 주어지는바, 재사용 노드 또는 독점 노드인지를 나타내는 일종의 지시값(indicator)이 된다.here,

The

Belonging to the first mobile base station

If the first mobile node is a reuse node, it is 1, and if it is an exclusive node, it is given as 0, which is a kind of indicator indicating whether it is a reuse node or an exclusive node.

는

번째 이동 기지국에서 재사용되는 서브채널의 총 개수이고

는

번째 이동 기지국에 의해 독점되는 서브채널의 총 개수이다. 따라서, 무선 통신 네트워크에서의 요구 서브채널 총 개수

는 다음 수학식과 같이 표현될 수 있다.As you can see from the above equation,

The

The total number of subchannels to be reused in the first mobile base station

The

The total number of subchannels monopolized by the first mobile base station. Therefore, the total number of required subchannels in the wireless communication network

Can be expressed as the following equation.

를 최소화하는

를 구함으로써 수행될 수 있다.As a result, the subchannel allocation according to the embodiment of the present invention

To minimize

Can be performed by

를 결정하여 서브채널 할당이 수행될 수 있다.For example, the optimal

Subchannel assignment may be performed by determining.

는 재사용 그룹을 의미하고,

는 독점 그룹을 의미한다.here,

Means reuse group,

Means exclusive group.

를 찾는 경우, 무차별 대입 검색 방법은

개의 경우를 고려하면 된다.Same as above

If you are looking for a, brute force search method

Consider the case of dogs.

를 최소화하는

를 결정하는 서브채널 할당은 위 수학식 중

가 1 또는 0이라는 제한을 완화(relaxation)하여

의 값이 모든

과

에 대하여 양의 실수라는 제한 하에

를 구하는 방식이 될 수 있다. 이하에서, 이러한 방식의 일례로 SA-K(Subchannel Assignment-Knapsack) 기법을 우선 설명한다.Meanwhile, in one embodiment of the present invention,

To minimize

The subchannel allocation to determine the

Relax the constraint that is 1 or 0

The value of all

and

Under the limitation of a positive mistake

It can be a way to obtain. Hereinafter, a subchannel assignment-knapsack (SA-K) technique will be described first as an example of such a scheme.

은 다음 수학식과 같은 관계를 가진다는 조건을 둘 수 있다.At this time, the maximum value of the total number of sub-channels to be reused in the mobile base station

May be a condition that has the same relationship as the following equation.

에 대해 완화된 제한 하에서는 모든 이동 기지국에서 재사용되는 서브채널의 총 개수를 동일한 값으로 놓을 수 있는 것이다. 즉, 이동 기지국에서 재사용되는 서브채널의 총 개수의 최대값은 다음 수학식을 만족하게 된다.Here, in consideration of the fact that all mobile base stations can maximize the total number of subchannels to be reused in order to minimize the total number of required subchannels, as described above.

Under the relaxed constraint for, the total number of subchannels reused in all mobile base stations can be set to the same value. That is, the maximum value of the total number of subchannels reused in the mobile base station satisfies the following equation.

를 결정하는 것이 된다.Therefore, the subchannel allocation by the SA-K scheme is optimal as shown in the following equation.

Will be determined.

For example, referring to Table 1, an optimization problem such as the above equation may be solved by the following process.

의 값이 작은 순으로 이동 노드를 재사용 노드로 지정하되, 그러한 지정을 재사용 서브채널 개수의 합이 특정 값을 초과하지 않을 때까지 수행하는 방식으로

를 결정할 수 있다.As can be seen in Table 1, for each mobile base station

Designate mobile nodes as reuse nodes in descending order of, but do so until the sum of the number of reuse subchannels does not exceed a certain value.

Can be determined.

번째 이동 기지국에 속한

번째 이동 노드에 대하여

라고 할 때,

를 오름차순으로 정렬한다. 여기서는 편의상

로 정렬된다고 가정한다.first,

Belonging to the first mobile base station

The first mobile node

When I say

Sorts in ascending order. For convenience here

Assume that is sorted by.

번째 이동 기지국에 대하여,

가 특정 값으로 주어지면

을 만족하는

을 구한다. 그리고, 첫 번째 이동 노드부터

번째 이동 노드까지는 재사용 그룹에 포함시킨다. 따라서, 특정

에 대하여, 요구 서브채널 총 개수는 다음 수학식과 같이 표현될 수 있다.next,

For the first mobile base station,

Is given by a certain value

To satisfy

. And from the first mobile node

The first mobile node is included in the reuse group. Thus, certain

For, the total number of required subchannels can be expressed as the following equation.

는

에 따른

값을 의미한다.here,

The

In accordance

It means the value.

는 0부터

까지

를 증분

씩 증가시켜 가면서 계산한다(단,

가 이용가능한 서브채널의 총 개수

보다 큰 경우에는,

까지만 계산함). 이후,

을 만족하는

를 선택한다. 이로써,

에 대해서는

로,

에 대해서는

으로 결정할 수 있다. 나아가, 모든 이동 기지국에 대하여 위와 같은 과정을 수행하여

를 결정할 수 있다.Meanwhile, the total number of required subchannels as described above

From 0

Till

Increment

Calculate it in increments (but,

Total number of subchannels available

If greater than

Only)). after,

To satisfy

. As a result,

About

in,

About

Can be determined. Further, by performing the above process for all mobile base stations

Can be determined.

를 최소화하는

를 결정하는 서브채널 할당은 위 수학식 6에 주어진 별도의 제한을 고려하지 않고 다음의 수학식과 같이

를 구하는 방식으로 이루어질 수 있다. 이하에서, 이러한 방식을 SA-I(Subchannel Assignment-Individual) 기법이라고 한다.Furthermore, in one embodiment of the present invention,

To minimize

The subchannel allocation for determining is determined by the following equation without considering the separate limitation given in Equation 6 above.

It can be done in a way to obtain. Hereinafter, this method is referred to as a subchannel assignment-individual (SA-I) technique.

을 정렬할 필요 없이 개개의 이동 노드에 대해

의 값이 0보다 작은지, 0인지, 아니면 0보다 큰지를 확인하여 재사용 노드 또는 독점 노드로 결정하는 방식으로 해결될 수 있다.For example, referring to Table 2, an optimization problem such as

For each mobile node without having to sort them

This can be solved by determining whether the value of is less than 0, 0, or greater than 0 to determine the reuse node or exclusive node.

을 만족하는 경우에는 그 이동 노드를 재사용 노드(

)로 결정하고,

이라면 그 이동 노드를 독점 노드(

)로 결정할 수 있다.For example, as shown in Table 2, for any mobile node

If it satisfies, the mobile node is reused.

),

If the mobile node is an exclusive node (

Can be determined.

5 is a diagram schematically illustrating a configuration of an apparatus for allocating subchannels according to an embodiment of the present invention.

The subchannel allocator 500 includes a subchannel number calculator 510 and a subchannel allocator 520. When the first mobile base station and the second mobile base station cause inter-cell interference, the subchannel number calculating unit 510 calculates the number of reused subchannels and the number of exclusive subchannels of each of the mobile nodes wirelessly connected to the first mobile base station. And calculating the number of reused subchannels and the number of exclusive subchannels of each of the mobile nodes wirelessly connected to the two mobile base stations. The subchannel allocator 520 is configured to minimize the total number of subchannels required by all mobile nodes based on the number of reused subchannels and the number of exclusive subchannels of each mobile node obtained by the subchannel number calculator 510. And assign a subchannel to each mobile node. For example, the subchannel allocator 520 may use the subchannel for partial frequency reuse for each mobile node through the dynamic partial frequency reuse scheme (eg, SA-K scheme or SA-I scheme) as described above. Determine use of a subchannel for intercell interference cancellation.

In addition, the subchannel allocation apparatus 500 may further include an interference detector 530 configured to detect whether mobile base stations cause inter-cell interference with each other. In addition, the subchannel allocating apparatus 500 may further include a channel information obtaining unit 540 configured to obtain channel information for calculating the reuse subchannel number and the exclusive subchannel number of each mobile node from each mobile base station. have. Furthermore, the subchannel allocation apparatus 500 may further include a power adjuster 580 configured to adjust the transmission powers of the mobile base stations. The power adjusting unit 580 allocates the transmission powers of the mobile base stations such that the sum of the transmission powers of the mobile base stations is minimum without the total number of required subchannels exceeding the total number of available subchannels. When the power is adjusted by the power adjusting unit 580, the number of reused subchannels and the number of exclusive subchannels of each of the mobile nodes is calculated by the subchannel number calculating unit 510, and then each mobile node in the subchannel allocating unit 520 is calculated. The subchannel may be reassigned for.

Embodiments of the present invention may be implemented in the form of programs that can be executed by various computer means to be recorded on a computer-readable recording medium. The computer readable recording medium may include program instructions, data files, data structures, etc. alone or in combination. The media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic-optical media such as floppy disks. magneto-optical media and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Such a medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, or the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may be embodied in various other forms without changing the technical spirit or essential features of the present invention. I can understand that. Therefore, the embodiments described above are illustrative in all respects and should not be understood as limiting.

120, 140: mobile base station, 160, 170, 180: mobile node

Claims (12)

Inter-cell interference between the number of reuse sub-channels and the number of exclusive sub-channels of each of the one or more first mobile nodes wirelessly connected to the first mobile base station. calculating the number of reused subchannels and the number of exclusive subchannels of each of the one or more second mobile nodes wirelessly connected with the second mobile base station causing inter-cell interference;
The one or more first mobile nodes and the one or more based on the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes and the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes. Allocating subchannels to the one or more first mobile nodes and the one or more second mobile nodes to minimize the total number of subchannels required by the second mobile node.
≪ / RTI > The number of reused subchannels and the number of exclusive subchannels of each of the one or more first mobile nodes wirelessly connected with the first mobile base station, and one wirelessly connected with the second mobile base station causing intercell interference between the first mobile base station and the first mobile base station; Calculating the number of reused subchannels and the number of exclusive subchannels of each of the second mobile nodes;
The one or more first mobile nodes and the one or more based on the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes and the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes. Assigning a subchannel to a second mobile node,
The subchannel allocating step determines that a reuse subchannel for partial frequency reuse or an exclusive subchannel for inter-cell interference cancellation is used for each of the one or more first mobile nodes and each of the one or more second mobile nodes. A value corresponding to the sum of the number of reuse subchannels of the mobile node in which the reuse subchannel among one or more first mobile nodes is determined to be used, and the value of the mobile node in which the reuse subchannel among the one or more second mobile nodes is determined to be used. A value corresponding to the total number of subchannels required by the at least one first mobile node and the at least one second mobile node under a mitigation condition that the value corresponding to the sum of the number of reuse subchannels has the same positive real value. Determining to minimize
Way. The method of claim 2,
The determination step is
Determining that a reuse subchannel or an exclusive subchannel is used for each of the one or more first mobile nodes based on the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes;
Determining that a reuse subchannel or an exclusive subchannel is used for each of the one or more second mobile nodes based on the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes.
≪ / RTI > The method according to claim 1 or 2,
Detecting whether the first mobile base station and the second mobile base station cause inter-cell interference with each other before the calculating step
≪ / RTI > The method according to claim 1 or 2,
Acquiring first channel information for calculating a reuse subchannel number and an exclusive subchannel number of the at least one first mobile node;
≪ / RTI > The method according to claim 1 or 2,
Receiving second channel information from the second mobile base station for calculating the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes. The number of reused subchannels and the number of exclusive subchannels of each of the one or more first mobile nodes wirelessly connected with the first mobile base station, and one wirelessly connected with the second mobile base station causing intercell interference between the first mobile base station and the first mobile base station; A subchannel number calculator configured to calculate the number of reused subchannels and the number of exclusive subchannels of each of the second mobile nodes;
The one or more first mobile nodes and the one or more based on the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes and the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes. A subchannel allocator configured to assign subchannels to the at least one first mobile node and the at least one second mobile node to minimize the total number of subchannels required by a second mobile node
/ RTI > The number of reused subchannels and the number of exclusive subchannels of each of the one or more first mobile nodes wirelessly connected with the first mobile base station, and one wirelessly connected with the second mobile base station causing intercell interference between the first mobile base station and the first mobile base station; A subchannel number calculator configured to calculate the number of reused subchannels and the number of exclusive subchannels of each of the second mobile nodes;
The one or more first mobile nodes and the one or more based on the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes and the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes. A subchannel allocator configured to assign a subchannel to a second mobile node,
The subchannel allocator also determines that a reuse subchannel for partial frequency reuse or an exclusive subchannel for inter-cell interference cancellation is used for each of the one or more first mobile nodes and the one or more second mobile nodes, respectively. A value corresponding to the sum of the number of reuse subchannels of the mobile node in which the reuse subchannel among one or more first mobile nodes is determined to be used, and the value of the mobile node in which the reuse subchannel among the one or more second mobile nodes is determined to be used. A value corresponding to the total number of subchannels required by the at least one first mobile node and the at least one second mobile node under a mitigation condition that the value corresponding to the sum of the number of reuse subchannels has the same positive real value. To minimize
Device. The method of claim 8,
It is determined that a reuse subchannel or an exclusive subchannel is used for each of the one or more first mobile nodes based on the reuse subchannel number and the exclusive subchannel number of the one or more first mobile nodes, and the one or more second mobiles. It is determined that a reuse subchannel or an exclusive subchannel is used for each of the one or more second mobile nodes based on the reuse subchannel number and the exclusive subchannel number of nodes.
Device. 9. The method according to claim 7 or 8,
An interference detector configured to detect whether the first mobile base station and the second mobile base station cause inter-cell interference with each other.
Lt; / RTI > 9. The method according to claim 7 or 8,
A channel information obtaining unit, configured to obtain first channel information for calculating the number of reused subchannels and the number of exclusive subchannels of the at least one first mobile node
Lt; / RTI > The method of claim 11,
The channel information obtaining unit is further configured to receive second channel information from the second mobile base station for calculating the reuse subchannel number and the exclusive subchannel number of the one or more second mobile nodes.
Device.

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