KR102091189B1 - Method for acquiring synchronization in signal frame for avoiding a cluster interference in ad-hoc network - Google Patents

Abstract

The present invention is a synchronization acquisition frame shared by all participating clusters to acquire synchronization for operation of a plurality of clusters configured in an ad hoc network, wherein the entire frame is composed of at least two slots, and one of the slots is a special slot. By dividing by the total number of participating clusters based on the frequency band of the network, a dedicated frequency band is allocated to each cluster, and each cluster transmits a synchronization signal to acquire synchronization in a dedicated frequency band. Provide a frame structure.

Description

A method for acquiring synchronization in a special frame for avoiding inter-cluster interference in an ad hoc network {METHOD FOR ACQUIRING SYNCHRONIZATION IN SIGNAL FRAME FOR AVOIDING A CLUSTER INTERFERENCE IN AD-HOC NETWORK}

The present invention relates to a method for obtaining synchronization in a special frame for avoiding inter-cluster interference in an ad hoc network.

Ad-hoc network (Ad-hoc network) is a network consisting of only a mobile host and does not have a fixed wired network. Therefore, it is suitable for a case where it is difficult to configure a wired network or is used for a short period of time after configuring the network. In an ad hoc network, there is no restriction on the movement of the host, and there is no need for a wired network and a base station, so it has the advantages of fast network configuration and low cost, especially for fast action The utility is noted in the military sector, where there are many situations where different units will cooperate.

Nodes on ad hoc networks must perform security and routing functions without the support of existing infrastructure. Also, since there is no node in charge of central management, each function is distributed to nodes in the network to perform. In addition, the ad hoc network can configure various types of networks that immediately reflect the status of nodes as the topology of the network changes frequently, and it must be able to continuously provide services regardless of the phase change of the network. In addition, nodes in the ad hoc network are limited in using resources such as CPU, memory, and battery, so efficient algorithms and mechanisms should be applied to minimize unnecessary resource usage so that maximum processing is possible with minimal resource usage.

With the recent advancement in communication technology, real-time communication is possible only when real-time communication is possible only when a tactical communication device is introduced to the medium and small-scale combat troops that are actually fighting in the forefront to fight, and real-time communication is possible. , It would be most effective to carry out communication by introducing mobile ad-hoc network (MANET) technology to the small combat units in the front (see Korean Patent Publication No. 2012-0031569).

MANET refers to a technology for establishing a communication system through interlocked communication between nodes without separate routing equipment in environments where the topology and mobility of nodes are severely changed. Such MANET is DSDV, AODV, OLSR, DSR, etc. on a single cluster. Various routing protocols have been studied and performance has been verified.

However, when a large number of clusters are formed, there are not many cases studied for technologies such as mutual interference between clusters, acquisition of synchronization between different clusters, and sharing of resource information, so there is an effective solution to stably introduce them into military tactics. This situation is urgently required.

The present invention has been devised to solve the above problems, and its object is to provide a method for obtaining synchronization in a special frame for avoiding inter-cluster interference in an ad hoc network.

In particular, in the present invention, it is an object of the present invention to provide a method for effectively avoiding interference between clusters by assuming that routing has already been implemented in a MANET situation so that a robust network can be built.

According to the present invention, for the operation of a plurality of clusters configured in an ad hoc network, as a synchronization acquisition frame shared by all participating clusters to acquire synchronization, the entire frame is composed of at least two slots, and one of the slots is special An ad hoc network characterized by dividing the total number of participating clusters based on the frequency band of the network as a slot to allocate a dedicated frequency band to each cluster, and allowing each cluster to transmit a synchronization signal to acquire synchronization in a dedicated frequency band. It gives my frame structure.

Preferably, the synchronization signal is characterized in that it is a preamble signal transmitted at a promised time.

Preferably, one of the slots is used as a control slot for transmitting resource allocation information, and a dedicated frequency band for each cluster is allocated to the control slot in the same way as the special slot, and resource allocation information is transmitted to the cluster through each band. Characterized in that to be delivered.

According to the present invention, there is an effect that interference avoidance between clusters is effectively performed in an ad hoc network.

When constructing an ad hoc network through the present invention, a network that is robust to interference between clusters can be constructed, and if interference is avoided, the probability of interference in the network is reduced, as well as an improved signal-to-noise interference ratio (SINR) gain. As a result, data throughput performance is improved and the effect of reducing the probability of outage can be achieved.

1 is a diagram illustrating an ad hoc network of a single cluster configuration.
2 is a view for explaining a resource allocation method of a single cluster configuration in an ad hoc network.
3 is a diagram for explaining a resource collision phenomenon when configuring multiple clusters in an ad hoc network.
4 is a diagram for explaining a resource allocation method of multiple clusters in an ad hoc network.
5 is a diagram for explaining a resource allocation method for avoiding inter-cluster interference in an ad hoc network according to an embodiment of the present invention.
6 is a diagram for explaining a multi-cluster operation situation in an ad hoc network.
7 is a view for explaining a shared resource allocation method for avoiding interference between clusters in an ad hoc network according to an embodiment of the present invention.
8 is a diagram for explaining a resource allocation method that divides shared resources from non-shared resources.
9 is a diagram illustrating a special slot structure for obtaining synchronization in an ad hoc network according to an embodiment of the present invention.
10 is a diagram for explaining a frame structure for resource allocation control information in an ad hoc network according to an embodiment of the present invention.

The present invention can be applied to various changes and may have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals are used for similar components.

Terms such as first, second, A, and B can be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term and / or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described herein, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

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

FIG. 1 is a diagram illustrating an ad hoc network of a single cluster configuration, and FIG. 2 is a diagram illustrating a resource allocation method of a single cluster configuration in an ad hoc network.

The ad hoc network scheme generally considered is a scheme consisting of a single cluster as shown in FIGS. 1 and 2.

However, when only a single cluster configuration scheme is considered as shown in FIGS. 1 and 2, when different ad hoc networks are formed adjacent to each other, interference between adjacent clusters occurs, resulting in resource collision as shown in FIG. 3. In such a multi-cluster configuration, the signal-to-noise interference ratio (SINR) of each cluster is lowered, and thus an outage phenomenon may occur.

3 is a diagram for explaining a resource collision phenomenon when configuring multiple clusters in an ad hoc network.

Therefore, in order to prevent the occurrence of such an outage phenomenon, an efficient resource allocation method capable of avoiding inter-cluster interference is required.

In the present invention, rather than a method of statically dividing and allocating resources, a method of dynamically dividing resources in consideration of QoS (Quality of Service) of a cluster, so that the efficiency of throughput can be expected compared to a conventional static method. do.

In the present invention, when multiple clusters are configured as shown in FIG. 4 in a single ad-hoc network, a resource allocation method capable of avoiding inter-cluster interference is proposed.

4 is a diagram for explaining a resource allocation method of multiple clusters in an ad hoc network.

In order to avoid interference between clusters in the ad hoc network proposed in the present invention, the following functions must be included in the protocol. The following functions are presented as a basic protocol for sharing resources between clusters.

1. Different clusters (individual units of a platoon or squad in the case of a group) have a unique ID and a unique sequence matching the unique ID.

2. The unique sequence of each cluster is used to obtain synchronization between clusters.

3. In order to acquire motivation, there is a specific special frame shared by all clusters.

4. In order to acquire synchronization between clusters in a special frame, unique sequences are transmitted, and different clusters acquire synchronization by receiving unique sequence signals. (Here, the method of implementing the physical layer for synchronizing acquisition relies on the implementation method of the receiving end algorithm, and a detailed description is omitted in the present invention.)

5. The synchronization acquisition method is a random access approach, in which the one that acquires synchronization first participates in resource allocation for avoidance of interference, and the cluster that failed to acquire synchronization is the next special through backoff. Compete in frames.

6. After synchronization is acquired, resource allocation information is shared in a control slot defined in the protocol.

The resource allocation method considers several dynamic methods as follows. Resources are divided and allocated in proportion through the values obtained for each cluster.

That is, in the ad hoc network according to the present invention, the resource allocation method for inter-cluster avoidance is a protocol for operating multiple clusters configured in the ad hoc network, where individual clusters have unique IDs and unique sequences matching them, and the entire cluster is shared. A special frame is configured in an ad hoc network, and for the special frame, each cluster transmits a unique sequence for obtaining synchronization and receives a unique sequence signal from the special frame to obtain synchronization; Clusters, which have obtained synchronization through the received unique sequence signal, participate in resource allocation, and clusters, which have not obtained synchronization, wait to participate in the next special frame through backoff; And after the synchronization is obtained, each cluster shares resource allocation information in a control slot defined in the protocol. For each cluster participating in the resource allocation, one of the cluster's channel capacity, the cluster's delay time, and the cluster's channel capacity and delay time is selected. Considering and dividing and allocating resources for each cluster; It is made to include.

1) Resource allocation method when only the channel capacity of the cluster is considered

When only the channel capacity of the cluster is considered, the sum of CUE is first calculated through Equation 1 below for resource allocation.

Here, k is an index of the cluster and CUE is a channel capacity of UE _i to UE _j . C (k) represents the sum of all CUEs.

The number of resources allocated to each cluster, N _{C (l)} , allocates frequency resources in proportion by calculating its C for the sum of (C), which is the total capacity of the cluster, as shown in Equation 2 below.

That is, in the step of dividing and allocating resources for each cluster in consideration of the channel capacity, in order to consider the channel capacity of the cluster, the sum (C (k)) of all channel capacity CUEs according to Equation 1 for clusters that have obtained synchronization is obtained. Estimating; And calculating the channel capacity (C) of each cluster with respect to the total channel capacity (sum of (C)) of the cluster according to Equation 2 to derive the number of resources allocated to each cluster (N _{C (l)} ). Allocating frequency resources proportionately to the cluster; Will include.

2) Resource allocation method when only the delay of the cluster is considered

When only the channel capacity of the cluster is considered, the sum of DUE is first calculated through Equation 2 below for resource allocation.

Where k is the index of the cluster and DUE is the delay time of UE _i to UE _j . D (k) represents the sum of all DUEs.

As the number of resources N _{D (l)} allocated to each cluster, frequency resources are allocated by calculating their D for the sum of (D), which is the total delay of the cluster, as in Equation 4 below.

That is, in the step of allocating and dividing resources for each cluster in consideration of the time delay, in order to consider the delay time of the cluster, the sum (D (k)) of all delay time DUEs according to Equation 3 is obtained for the clusters that have obtained synchronization. Estimating; And calculating the delay time (D) of each cluster with respect to the total delay time (sum of (D)) of the cluster according to Equation 4 to derive the number of resources allocated to each cluster (N _{D (l)} ). Allocating frequency resources proportionately to the cluster; Will include.

3) Resource allocation method when considering both capacity and delay of cluster

에 따라 비율적으로 고려하여 T(k)를 산정하게 된다. If both the channel capacity and the delay of the cluster are considered, C (k) and D (k) are first calculated through Equation 5 below for resource allocation.

According to the ratio, T (k) is calculated.

The number of resources allocated to each cluster, N _{T (l),} is allocated as a frequency resource by calculating the result of the agreement considering the total capacity and delay of the cluster in proportion as shown in Equation 6 and the T of the cluster in proportion. Is done.

Here, FIG. 5 is a diagram for explaining a resource allocation method for avoiding inter-cluster interference in an ad hoc network according to an embodiment of the present invention. In the resource allocation scheme proposed in the present invention, as shown in FIG. 5 (three clusters), each cluster will allocate resources in a top-down manner according to its cell ID size.

That is, in the step of dividing and allocating resources for each cluster in consideration of both the capacity and the delay of the cluster, in order to consider both the channel capacity and the delay time of the cluster, all of the clusters that have obtained synchronization according to Equations 1 and 3 Calculating the sum (C (k)) of the channel capacity CUE and the sum (D (k)) of all DUEs and calculating the sum (T (k)) through Equation 5; And the number of resources allocated to each cluster (N _{T (l)} ) is _calculated according to Equation (6) to calculate the channel capacity and delay time of each cluster relative to the total channel capacity and total delay time of the cluster, and proportionate to each cluster. Allocating frequency resources; Will include.

4) Resource allocation method that distinguishes shared and non-shared resources

When the above-described actual resource collision situation of FIG. 4 is expressed as using a balanced antenna, it can be expressed as in FIG. 6. 6 is a diagram for explaining a multi-cluster operation situation in an ad hoc network.

In other words, even if there is no interference in the same cluster, it may appear that interference between different clusters is large. The present invention proposes a method of designating a link capable of sharing resources between clusters in order to utilize resources between clusters as efficiently as possible. When each signal has a sufficiently large signal-to-noise interference ratio (SINR) measured in a special frame section calculated in Equation 7 below, scheduling is performed on all resources other than the resource section specified in the control frame. Suggest to be free.

는 상수값이고, 수학식 8은

가 임계값보다 큰 경우의 노드의 iD 값을 의미한다. 수학식 9의 I는 전체 자원구간에서 자유롭게 자원할당이 가능한 UE ID의 집합으로 정의한다.In Equation 8 above

Is a constant value, and Equation 8 is

When i is greater than the threshold, it means the iD value of the node. I in Equation 9 is defined as a set of UE IDs that can be freely allocated resources in the entire resource section.

Equation 7 defines a signal-to-noise interference ratio (SINR) from an i terminal to a j terminal. In this case, interference of the terminal from the i terminal to the k terminal is excluded. Because it is a signal sent from terminal i to terminal j, terminal j should not be recognized as interference.

보다 큰 단말의 인덱스(index)를 나타내게 된다. 따라서 임계값 보다 큰 경우에는 자원을 서로 공유하는 것이고 I의 여집합인 단말들은 정해진 구역내에서만 자원을 할당하게 될 것이다. 임계값 보다 큰 경우에는 자원을 서로 공유해도 다른 단말이 미치는 간섭의 영향이 신호를 주고 받는 시그널 전력보다 작기 때문에 충분히 수용가능하므로 서로 자원을 공유하는 것이 가능하다. 서로 자원을 공유하지 못하는 단말들은 I의 여집합이 되고, 이 단말들이 사용하고자 하는 자원의 양은 수학식 7, 8 및 9에 따라 또 다시 나누어지게 될 것이다. Equation 8 represents index i ', which is the threshold

The index of the larger terminal is displayed. Therefore, if it is larger than the threshold value, the resources are shared with each other, and the terminals, which are a subset of I, will allocate resources only within a designated area. When the value is greater than the threshold value, it is possible to share resources with each other because the effects of interference from other terminals are smaller than the signal powers to which signals are transmitted and received even if resources are shared with each other. Terminals that do not share resources with each other will be a subset of I, and the amount of resources to be used by these terminals will be divided again according to Equations 7, 8 and 9.

7 is a view for explaining a shared resource allocation method for avoiding interference between clusters in an ad hoc network according to an embodiment of the present invention. As shown in FIG. 7 (in the case of three clusters), each cluster allocates resources to be used and shares with each other, but nodes belonging to I of Equation (9) can use shared resources in addition to the allocated resources. will be.

8 is a view for explaining a resource allocation method that divides the above-mentioned shared resources from non-shared resources.

That is, in the ad hoc network according to the present invention, a method for allocating shared resources for inter-cluster avoidance is a protocol for operating a plurality of clusters configured in an ad hoc network, where each cluster has a unique ID and a unique sequence matching it, and the entire cluster A shared special frame is configured in an ad hoc network, and for the special frame, each cluster transmits a unique sequence for synchronization acquisition and receives a unique sequence signal from the special frame to obtain synchronization; Clusters, which have obtained synchronization through the received unique sequence signal, participate in resource allocation, and clusters, which have not obtained synchronization, wait to participate in the next special frame through backoff; And after synchronization is obtained, each cluster shares resource allocation information in a control slot defined in a protocol, and classifies and divides shared resources into clusters by classifying shared resources and non-shared resources in consideration of the influence of interference between clusters participating in the resource allocation. To do; Will include.

)를 산정하고, 산정된 신호대잡음간섭비(

)를 수학식 8에 대입해 임계값(

)과 비교함으로써 임계값(

) 보다 큰 신호대잡음간섭비(

)를 가지는 노드의 ID를 도출하는 단계; 상기 도출된 노드의 ID들을 이용해 전체 자원구간에서 자원할당이 가능한 UE ID의 집합(

)을 수학식 9를 통해 정의하는 단계; 상기 집합(

)에 속한 UE ID에 대해 할당된 자원블록(RB) 외에 클러스터의 공유 자원을 추가 사용할 수 있도록 할당하는 단계; 를 포함하게 될 것이다. Here, the step of dividing and allocating shared resources for each cluster includes: designating a link for sharing resources between clusters for each cluster; Signal-to-noise interference ratio according to equation (7) for each link cluster

), And the calculated signal-to-noise interference ratio (

) To Equation 8 to substitute the threshold (

) To compare with the threshold (

) Greater signal-to-noise interference ratio (

Deriving the ID of the node having); A set of UE IDs capable of allocating resources in the entire resource section using the derived node IDs (

) Through Equation 9; Above set (

Allocating the shared resource of the cluster to be used in addition to the resource block (RB) allocated for the UE ID belonging to); Will include.

)에 속하지 않은 UE ID에 대해 상기 수학식 7 내지 9에 따라 전체 자원구간에서 자원할당이 가능한 UE ID의 집합(

)을 재선정하여 할당된 자원블록(RB) 외에 클러스터의 공유 자원을 추가 사용할 수 있도록 할당하는 단계; 를 반복 진행할 수 있다. In addition, after the step of allocating the shared resources of the cluster for further use, the set (

A set of UE IDs capable of resource allocation in all resource sections according to Equations 7 to 9 above for UE IDs not belonging to)

) To reselect and allocate the shared resource of the cluster to be used in addition to the allocated resource block (RB); Can be repeated.

(5) Synchronization acquisition frame structure

The present invention proposes a method for obtaining synchronization between clusters because it is impossible to share information for avoiding interference between nodes when each cluster is out of sync with each other.

Synchronization considers transmitting preamble signals known to each other at a mutually agreed upon time. Here, PN sequence, Barker sequence, Zadoff-chu, etc. may be considered as the preamble signal. Which signal is selected is left to freedom, and detailed description of this part is omitted in the present invention.

The frame for obtaining synchronization considered in the present invention will be described with reference to FIG. 9 as follows. 9 is a diagram illustrating a special slot structure for obtaining synchronization in an ad hoc network according to an embodiment of the present invention.

It may be practically one of the entire frames of S0 to S7, and this is considered according to a predefined method. In the present invention, different F_widths are allocated to each cluster ID and a preamble signal is transmitted within a predetermined band. This is because interference between preamble signals can be reduced as much as possible. Also, this method is effective for determining whether a jamming signal is present. Here, F_width is calculated by the following equation (10).

In order to efficiently utilize resources for obtaining a synchronization unit, a special slot structure as shown in FIG. 9 is proposed. In order to acquire synchronization with other clusters, bandpass filtering is required in the physical layer (PHY layer) for F_width. It is suggested that F_width is determined by promising between clusters in advance according to the number of participating clusters.

(6) Control information frame structure

The structure of the control information frame in the present invention will be described with reference to FIG. 10 as follows. 10 is a diagram for explaining a frame structure for resource allocation control information in an ad hoc network according to an embodiment of the present invention.

It is considered to transmit control information for transmitting resource allocation information according to F_width allocated for each cluster. This is because transmitting only resource allocation information with a small amount of data in one slot has many disadvantages in terms of resource efficiency. In addition, it is advantageous to inter-cluster interference by using a predetermined resource for each cluster.

The frame structure in the ad hoc network is necessary to recognize the parts interfering with different clusters, and is also essential for sharing resource allocation information with each other.

First, in order to be motivated, mutual promises between terminals participating in the same network are important. The proposed method divides the total number of clusters on the frequency axis and allocates them so that there is no interference with each other. And the control information is transmitted in the same location where the synchronization signal is located, so that there is no mutual damage. At this time, normal data can be transmitted without transmitting a synchronous signal, and the synchronous signal overlaps with the data signal to distinguish the signal due to the nature of the synchronous signal.

That is, the frame structure in the ad hoc network according to the present invention is a synchronization acquisition frame shared by all participating clusters to acquire synchronization for operation of a plurality of clusters configured in the ad hoc network, and the entire frame is composed of at least two or more slots. By dividing one of the slots into a special slot and dividing it by the total number of participating clusters based on the frequency band of the network, a dedicated frequency band is allocated to each cluster, and each cluster transmits a synchronization signal to acquire synchronization in the dedicated frequency band. Will be done.

Here, the synchronization signal is a preamble signal transmitted at a promised time, and one of the slots is used as a control slot for transmitting resource allocation information, and a dedicated frequency band for each cluster is assigned to the control slot in the same way as the special slot. By assigning, resource allocation information is transmitted to the cluster through each band.

As described above, the optimal embodiment has been disclosed in the drawings and the specification. Although specific terms have been used herein, they are only used for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the claims or the claims. Therefore, those skilled in the art will understand that various modifications and other equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

Claims (3)

As a protocol for the operation of a plurality of clusters configured in an ad hoc network, each cluster has a unique ID and a unique sequence matching it, and special frames shared by all clusters are configured in an ad hoc network, and each cluster acquires synchronization for the special frames. For the step of transmitting a unique sequence and receiving a unique sequence signal from the special frame to obtain synchronization;
Clusters, which have obtained synchronization through the received unique sequence signal, participate in resource allocation, and clusters that have failed to obtain synchronization wait for participation in the next special frame through backoff; And
After the synchronization is obtained, each cluster shares resource allocation information in a control slot defined in a protocol, and classifies and divides shared resources into clusters by classifying shared resources and non-shared resources in consideration of the effect of interference between clusters participating in the resource allocation. step; It includes,
The step of dividing and allocating shared resources for each cluster is:
Designating a link for each cluster to share resources between clusters;
Signal-to-noise interference ratio according to Equation 1 below for each link cluster:

), And the calculated signal-to-noise interference ratio (

) By substituting in Equation 2 below.

) To compare with the threshold (

) Greater signal-to-noise interference ratio (

Deriving the ID of the node having);
A set of UE IDs capable of allocating resources in the entire resource section using the derived node IDs (

) Is defined by the following equation (3);
Above set (

Allocating the shared resource of the cluster to be used in addition to the resource block (RB) allocated for the UE ID belonging to); It includes,
As a method for obtaining synchronization in a special frame for all participating clusters to acquire synchronization for operation of a plurality of clusters configured in an ad hoc network,
The entire frame of the special frame is composed of at least two or more slots, and one of the slots is a special slot, divided by the total number of participating clusters based on the frequency band of the network, and a dedicated frequency band is allocated to each cluster, and each cluster Method for acquiring synchronization in a special frame for inter-cluster avoidance in an ad hoc network, characterized in that a synchronization signal is transmitted for synchronization acquisition in a dedicated frequency band.
[Equation 1]

[Equation 2]

[Equation 3]

In Equation 2 above

Indicates a constant value.
According to claim 1,
The synchronization signal is a method for obtaining synchronization in a special frame for avoiding inter-cluster interference in an ad hoc network, characterized in that it is a preamble signal transmitted at a promised time.
The method according to claim 1 or 2,
One of the slots is used as a control slot for transmitting resource allocation information, and a dedicated frequency band for each cluster is allocated to the control slot in the same way as the special slot so that resource allocation information is transmitted to the cluster through each band. Method for obtaining synchronization in a special frame for avoiding inter-cluster interference in an ad hoc network characterized by the above-mentioned.

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