KR101774558B1 - Method and apparatus for access control in wireless communication system - Google Patents

Abstract

In a wireless mesh network of an Orthogonal Frequency Division Multiple Access scheme, a communication node receives information of a next hop of one hop node and two hop nodes through the one hop node, After determining the next transmission time using the next transmission interval of one hop node and two hop nodes, information of the next transmission time is transmitted together with the information of the transmission time of one hop node received from one hop node To the one hop node of the node.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for controlling access in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection control method and apparatus in a wireless communication system, and more particularly, to a connection control method in a wireless mesh network system using an Orthogonal Frequency Division Multiple Access (OFDMA) scheme.

Access control for a conventional wireless mesh network has been proposed for Orthogonal Frequency Division Multiplexing (OFDM) based Time Division Multiple Access (TDMA). However, this connection control not only increases the required transmission power but also reduces the resource allocation efficiency for a small burst size when the length of OFFDM fast Fourier transform is long.

In particular, unlike a cellular network, a guard symbol required for transmission / reception switching is allocated for each transmission in a wireless mesh network, so that the efficiency of a burst transmission resource of a small size may be seriously degraded.

In order to increase the efficiency of resource utilization, a wireless mesh network based on Orthogonal Frequency Division Multiple Access (OFDMA) should be introduced. Accordingly, a connection control method for an OFDMA based wireless mesh network is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an access control method and apparatus for an OFDMA-based wireless mesh network.

According to an embodiment of the present invention, there is provided a connection control method at a communication node of a wireless mesh network of an orthogonal frequency division multiple access scheme. The access control method includes receiving information on a next transmission time point of a one-hop node and a two-hop node through the one hop node, using information of a next transmission time of the one hop node and the two- And determining a subframe and a subchannel corresponding to a next transmission time using the next transmission interval of the one hop node and the two hop node, And sending the information to its one hop node.

Wherein the receiving step comprises receiving first and second parameters of the one-hop node and first to third parameters of the two-hop node, wherein the next transmission interval of the one-hop node is calculated by the following equation: ReceiveTime + 2 ^Exp * Mx ≤ next transmission interval ^{<ReceiveTime + 2 Exp * (Mx} + 1) " is obtained by the two next transmission interval of hop node is the next calculation of ^{the" ReceiveTime + 2 Exp * Mx +} RxFwdTimeDiff ≤ then Can be obtained by a transmission interval &lt; ReceiveTime + 2 ^Exp * (Mx + 1) + RxFwdTimeDiff &quot;. Here, the first, second, and third parameters correspond to Exp, Mx, and RxFwdTimeDiff, respectively, and the ReceiveTime may indicate the time when the first to third parameters are received.

Wherein the step of transmitting information of the next transmission time to its one hop node comprises the steps of calculating the first parameter and the second parameter corresponding to the next transmission time of the communication node, Parameter to the one-hop node of its own.

The step of calculating the first parameter and the second parameter may further include the steps of: determining the first parameter according to at least one of a system setting value, a service quality, and a priority; and determining the first parameter and the next transmission time And calculating the second parameter using the second parameter.

Wherein the step of transmitting information of the next transmission time to the one hop node of its own node comprises the steps of: receiving the first and second parameters of the one hop node and transmitting the first parameter and the second parameter of the communication node Obtaining the third parameter from the time difference of the first node, and transmitting the first to third parameters of the one hop node to the one hop node.

The step of transmitting the information of the next transmission time to the one-hop node of its own may include setting information of the subchannel corresponding to the next transmission time as a bitmap and transmitting the information.

Wherein the determining step comprises the steps of: selecting a contending node to participate in a competition of a subframe resource with itself using a next transmission interval of the one hop node and the two hop node; Determining a subframe to be transmitted next, selecting a subchannel level competing node to participate in a competition of a subchannel resource with the subframe to be transmitted next, And determining a subchannel to be transmitted next using the next transmission interval of the subchannel level competing node for each of the channels.

Wherein the step of selecting the competing node comprises: a first condition that a next transmission interval of the one hop node and the two hop nodes, including the temporary transmission point of the communication node, among the one hop node and the two hop nodes, And a second condition that a sum of a minimum value of a next transmission interval of the two hop nodes and a holdoff time that can not be transmitted by the one hop node and the two hop node is smaller than a temporary transmission time of the communication node, And a third condition that does not allow the node to compete with the third node.

The step of selecting the subframe level contention node may further include changing the holdoff time according to at least one of a density, a delay condition, a resource period, and a quantity of a communication node in the wireless mesh network.

The step of determining a subframe to be transmitted next may include performing a mesh selection algorithm using one hop node and a target subframe among the competing nodes.

Wherein the step of selecting the subchannel level competing node comprises the step of performing its own mesh selection algorithm with one hop node of each of the two hop nodes of the competing nodes, And selecting the selected two-hop node as the subchannel level competing node.

The step of determining a subchannel to be transmitted next may include performing a mesh selection algorithm using the subchannel level contention node, the target subframe, and the subchannel for each of the subchannels of the subframe to be transmitted next .

According to another embodiment of the present invention, there is provided a connection control apparatus for a communication node in a wireless mesh network of an Orthogonal Frequency Division Multiple Access scheme. The connection control apparatus includes a transmission time determination unit and an information transmission unit. The transmission time determination unit calculates a next transmission interval of the one hop node and the two hop nodes and calculates a transmission interval of the subframe and the subchannel corresponding to the next transmission time of the communication node using the next transmission interval of the one hop node and the two- . And the information transmission unit obtains at least one parameter used for expressing the next transmission interval of the communication node from the next transmission point of the communication node and transmits the at least one parameter to the one hop node of the communication node.

Wherein the information transmission unit determines the first parameter according to at least one of a system setting value, a service quality, and a priority, and transmits the first parameter and the next transmission point of time of the communication node, To calculate the second parameter.

The connection control apparatus may further include an information receiving unit receiving the first and second parameters indicating the next transmission time of the one hop node from the one hop node. Here, the information transmission unit may acquire a third parameter from a time difference between a time point at which the first and second parameters of the one hop node are received and a time at which the at least one parameter of the communication node is to be transmitted, The first to third parameters of the at least one parameter may be transmitted together with the at least one parameter.

According to an embodiment of the present invention, it is possible to improve network reliability and stability by avoiding collision between adjacent nodes in an OFDMA-based wireless mesh network, and to minimize uncertainty of transmission of neighbor nodes, thereby increasing resource utilization and frequency efficiency .

1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.
2 is a diagram illustrating resources in an OFDMA-based wireless mesh network system according to an embodiment of the present invention.
3 is a diagram schematically illustrating a communication node according to an embodiment of the present invention.
4 is a flowchart illustrating a connection control method performed by the communication node of FIG.
5 is a flowchart illustrating a method of determining a next transmission time in a communication node according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise.

A connection control method and apparatus in a wireless communication system according to an embodiment of the present invention will now be described in detail with reference to the drawings.

1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.

A wireless network system according to an embodiment of the present invention represents a network system in which communication is established between communication nodes constituting a network such as a wireless mesh network or a mobile ad hoc network.

FIG. 1 illustrates a wireless mesh network system in which a plurality of nodes communicate in a multi-hop manner in a wireless network system to which an embodiment of the present invention is applied.

Referring to FIG. 1, a wireless mesh network system 100 includes a plurality of communication nodes 110 and 120.

The communication node 110 may be an access point serving as a base station and the communication node 120 may be a terminal communicating with the communication node 110.

These communication nodes 110 and 120 perform wireless communication using OFDMA (Orthogonal Frequency Division Multiple Access) scheme.

In addition, the communication nodes 110 and 120 select neighboring communication nodes according to the transmission power reaching range (or other conditions), exchange reservation resource information used for the next transmission with the neighboring communication node, (Or resource) connection so that collision with neighboring communication nodes does not occur.

Typically, a neighboring communication node capable of receiving a transmission power of any one of the communication nodes 110 is defined as a 1-hop node of the communication node 110, and one hop node of the one- Hop nodes of the communication node 110 are defined as two-hop nodes of the communication node 110, which do not overlap with one hop node of the communication node 110. [

2 is a diagram illustrating resources in an OFDMA-based wireless mesh network system according to an embodiment of the present invention.

Referring to FIG. 2, resources in an OFDMA-based wireless mesh network system are divided into a time axis and a frequency axis. In the following, time-base resources are collectively referred to as a subframe and frequency axis resources are referred to as subchannels.

That is, the communication nodes 110 and 120 of the OFDMA-based wireless mesh network system control which subchannel of a subframe to transmit resources. At this time, the communication nodes 110 and 120 can only transmit or receive within one subframe.

In the OFDMA-based wireless mesh network system, the connection conditions for preventing collision and simultaneous transmission and reception in reception from one hop node are as follows. The first condition is that if any communication node transmits any one of its one-hop nodes, it can not transmit in its subframe. This is a condition for preventing a simultaneous transmission and reception problem in which a communication node makes a transmission and one of the one-hop nodes of the communication node transmits to the communication node. In particular, when each communication node must broadcast, the first condition must be satisfied. The second condition is that any communication node can be received from multiple one-hop nodes through different sub-channels in one sub-frame. In a time division multiple access (TDMA) wireless mesh network system based on Orthogonal Frequency Division Multiplexing (OFDM), since the multiple access to the frequency axis is not possible, this second condition does not hold.

The communication nodes 110 and 120 perform connection control that satisfies these two connection conditions, thereby preventing collision upon reception from the one-hop node and preventing simultaneous transmission and reception.

Next, a connection control method that satisfies the connection condition of a communication node in the above-described OFDMA-based wireless mesh network system will be described.

FIG. 3 is a schematic diagram of a communication node according to an embodiment of the present invention, and FIG. 4 is a flowchart illustrating a connection control method performed by the communication node of FIG.

3 and 4, the communication node 300 may be a connection control device that performs connection control of a channel (or resource), and may be a connection control device of the communication nodes 110 and 120 of FIG.

Referring to FIG. 3, the communication node 300 includes an information receiving unit 310, a transmission time determining unit 320, and an information transmitting unit 330.

Referring to FIG. 4, the information receiving unit 310 receives reservation resource information of neighboring communication nodes and an identifier (e.g., a node ID) of a neighboring communication node from its one-hop node (S410). Here, the neighboring communication node may include one hop node of the communication node 300 and two hop nodes of the communication node 300.

In addition, the reservation resource information may include reservation information of a subframe indicating a next transmission time and reservation information of a subchannel.

The reservation information of the subframe may include parameters (Exp, Mx, RxFwdTimeDiff) that can indicate the next transmission time. The parameter Exp is used to define a pause time after transmission and notify the next transmission interval, and the parameter Mx is also used to notify the next transmission interval. The parameter (RxFwdTimeDiff) is a value for compensating a time difference between when a next hop information of one hop node is received and when it is delivered to one hop node.

The reservation information of the subchannel indicates which subchannel of the subframe to transmit, and can be set using a bitmap composed of the number of subchannels in one subframe. For example, when one subframe is composed of four subchannels, the reservation information of the subchannel can be set to four bits. At this time, each bit is set to 1 if the subchannel is reserved, otherwise it can be set to 0, and vice versa.

The transmission time determination unit 320 determines the next transmission time (NextXmtTime) to satisfy the above-mentioned connection condition using the reservation resource information of the neighboring communication nodes received from the one-hop node of its own (S420). The transmission time determination unit 320 determines a next transmission time (NextXmtTime), which is next transmission resource information, and a subchannel to be used in the next transmission time (NextXmtTime) before the previously reserved transmission time (ReservedXmtTime).

When the subchannel to be used in the next transmission time (NextXmtTime) and the next transmission time (NextXmtTime) is determined by the transmission time determination unit 320, the information transmission unit 330 transmits its identifier, next determined transmission time (NextXmtTime) Hop resource information corresponding to the subchannel information to be used in the NextNextTime (step S430). At this time, the information transmission unit 330 also transmits the reserved resource information of the own hop node received from its one hop node.

More specifically, the information transmission unit 330 converts the next transmission time (NextXmtTime) into parameters of Exp and Mx, and transmits the parameters (Exp, Mx) to its one-hop node. Here, the parameters Exp and Mx represent time intervals including the relative difference between the already reserved transmission time (ReservedXmtTime) to which the parameter (Exp, Mx) is to be transmitted and the next transmission time. Also, the information transmission unit 300 transmits reservation information of the subchannel corresponding to the next transmission time together with parameters (Exp, Mx).

Next, a method of calculating the parameters (Exp, Mx) in the information transmission unit 330 will be described in detail.

When the next transmission time is determined by the transmission time determination unit 320, the information transmission unit 330 expresses in which subframe the next transmission is to be performed by using the parameters Exp and Mx, Lt; RTI ID = 0.0 &gt; node &lt; / RTI &gt; Herein, the information transmission unit 330 means a time difference between the time when the parameters (Exp, Mx) received from the one-hop node and the time when the parameters (Exp, Mx) are received from the one-hop node and the time point Parameter (RxFwdTimeDiff) is calculated and transmitted to the one-hop node.

The parameter (Exp, Mx, RxFwdTimeDiff) is a parameter indicating that the corresponding hop or two-hop communication node is going to transmit within the next transmission interval (NextXmtTimeInterval). First, the next transmission interval (NextXmtTimeInterval) of one hop node derived from Exp and Mx, Can be calculated as Equation (1)

[Equation 1]

ReceiveTime + 2 ^Exp * Mx? NextXmtTimeInterval <ReceiveTime + 2 ^Exp * (Mx + 1)

In Equation (1), the next transmission interval (NextXmtTimeInterval) is represented by a subframe number. ReceiveTime means the subframe number at the time of receiving the parameters (Exp, Mx). Since the transmitting node has transmitted the parameters (Exp, Mx) in the already reserved transmission time (ReservedXmtTime), the ReceiveTime of the receiving node is the same as the reserved transmission time (ReservedXmtTime) of the transmitting node. The subframe number is the reference time that is synchronized throughout the network. The range of the subframe number is limited to 0 (MaxSubframeNumber-1) and circulated. Here, MaxSubframeNumber is the maximum subframe number limited by the bit size used when the communication node broadcasts the related message for subframe synchronization. The units of ReceiveTime and HoldoffTime described later all mean subframe number or subframe number difference.

Exp and Mx are relative expressions of the next transmission interval from the reserved transmission point (ReservedXmtTime) of one hop node and two hop node. Therefore, if ReceiveTime is added as shown in Equation 1, the next transmission interval (NextXmtTimeInterval) It can be expressed in time.

The next transmission interval (NextXmtTimeInterval) of the two-hop node includes a parameter (RxFwdTimeDiff) indicating the time difference between the time when the one hop node that transmits the parameters (Exp, Mx) of the two- Can be calculated as shown in Equation (2) using the parameters (Exp, Mx) of the node.

&Quot; (2) &quot;

^{ReceiveTime + 2 Exp * Mx + RxFwdTimeDiff} ≤ NextXmtTimeInterval <ReceiveTime + 2 Exp * (Mx + 1) + RxFwdTimeDiff

The communication node 300 may be fixed as a system parameter to have the same Exp in all the communication nodes, or may be used as a value different from other communication nodes by variably using Exp according to QoS or priority. If the communication node 300 requires a higher QoS or a higher priority, such as a small delay or a higher rate, it will lower the parameter Exp, and conversely if it requires a large delay or lower QoS or lower priority, The parameter Exp can be increased to improve the transmission opportunity of the communication node.

The information transmission unit 330 can obtain Mx from the Exp determined for the communication node 300 as shown in Equation (3).

&Quot; (3) &quot;

Mx = floor ((NextXmtTime - ReservedXmtTime) / 2 ^Exp )

In Equation (3), floor () means down, and ReservedXmtTime represents the absolute time at which the parameter (Exp, Mx) is transmitted. NextXmtTime is an absolute time, and indicates the next transmission time reserved by the transmission time determination unit 320. [

Referring to Equation (3), the information transmission unit 330 subtracts the time (ReservedXmtTime) at which the parameter (Exp, Mx) is transmitted in the next transmission time (NextXmtTime) from the parameter (Mx).

The information transmission unit 330 transmits the reservation information of the subchannel to which the parameters (Exp, Mx) representing the next transmission interval received from the one hop nodes of the communication node 300 are transmitted and the parameters Exp and Mx, To the nodes. The information transmitter 330 calculates a parameter RxFwdTimeDiff indicating a time difference between a time point (ReceiveTime) of receiving a parameter (Exp, Mx) indicating the next transmission interval of one hop nodes and a time point (ReservedXmtTime) (Exp, Mx) of the one hop node and the reservation information of the subchannel to its one hop nodes. That is, the parameter RxFwdTimeDiff can be calculated as shown in Equation (4).

&Quot; (4) &quot;

RxFwdTimeDiff = ReservedXmtTime - ReceiveTime

In this way, all the communication nodes can know the reserved subchannels in the next transmission interval and the next transmission interval of the two-hop nodes as well as their one-hop nodes.

In addition, the information transmitter 330 determines whether the minimum value of the next transmission interval of its one-hop nodes is earlier than the current transmission time (ReservedXmtTime), and determines that the next transmission time of one- In the previous case, since this is meaningless information, the parameters (Exp, Mx, RxFwdTimeDiff) of the corresponding one-hop node and reservation information of the subchannel are not transmitted. In this way, overhead can be reduced.

5 is a flowchart illustrating a method of determining a next transmission time in a communication node according to an embodiment of the present invention.

5, the information receiving unit 310 of the communication node 300 receives an identifier and reservation resource information of its one hop node and two hop nodes from its one hop node, that is, parameters (Exp, Mx, RxFwdTimeDiff) Upon receiving the reservation information of the subchannel, the scheduling unit 320 transmits the received reservation resource information to the transmission time determination unit 320.

The transmission time determination unit 320 of the communication node 300 receives the identifier and reservation resource information of the one hop node and the two hop node of the communication node 300 in operation S501, The next transmission interval NextXmtTimeInterval of the one-hop node and the two-hop node is calculated using parameters (Exp, Mx) and parameters (Exp, Mx, RxFwdTimeDiff) of the two-hop node (S502). The next transmission interval (NextXmtTimeInterval) of the one-hop node and the two-hop node can be calculated from Equations 1 and 2, respectively.

The communication node 300 is unable to transmit for all transmissions during a holdoff time (HoldoffTime) after transmission. This allows a statistically guaranteed delay within a certain range for the transmission of one hop or two hop nodes. The holdoff time is determined as shown in Equation (5).

&Quot; (5) &quot;

HoldoffTime = c * 2 ^Exp

In Equation (5), c is a system parameter, which can be changed in accordance with the density of the communication node, the delay condition, the cycle of a given resource, and the amount of resources in the wireless mesh network system.

Meanwhile, in the conventional OFDM-based TDMA wireless mesh network, the holdoff time is 2 ^{(Exp + 4)} . That is, since c is fixed to 2 ⁴ in the conventional OFDM-based TDMA wireless mesh network, the resource utilization rate can be reduced or the delay can be increased.

On the other hand, in the embodiment of the present invention, the holdoff time can be changed according to the density of the communication node, the delay condition, the period of a given resource, and the amount of resources as in Equation (5).

In step S503, the communication node 300 calculates an initial value of a temporary transmission time (TempXmtTime) that can be the next transmission time of the reserved transmission time (ReservedXmtTime) in consideration of the holdoff time. The initial value of the temporary transmission time (TempXmtTime) is defined as shown in Equation (6).

&Quot; (6) &quot;

TempXmtTime = ReservedXmtTime + HoldoffTime

As described above, since the communication node 300 has a pause period for at least a holdoff time after a reserved transmission time (ReservedXmtTime) and can transmit from thereafter, the earliest possible transmission point to the next transmission time is math Is calculated as shown in Equation (6).

The temporary transmission time TempXmtTime is a subframe number that can be the next transmission time point of the already reserved transmission time (ReservedXmtTime). In the temporary transmission time TempXmtTime, i.e., when the communication node 300 won the competition Or a mesh selection algorithm), the temporary transmission time (TempXmtTime) becomes the next transmission point of the communication node 300. [ If it can not win the competition (or if it is not selected in the mesh selection algorithm), the temporary transmission time (TempXmtTime) is increased by 1 (S506) and then compete again for the temporary transmission time. The communication node 300 selects a competition node considering the next transmission interval (NextXmtTimeInterval) and the temporary transmission time (TempXmtTime) of the one-hop and two-hop nodes calculated in the previous step (S504).

The criterion for selecting a contending node may be one of the following three conditions.

First, the next transmission interval (NextXmtTimeInterval) includes the temporary transmission time (TempXmtTime) of the communication node 300.

Second, the value obtained by adding the minimum value of the next transmission interval (NextXmtTimeInterval) and the holdoff time of the communication node is smaller than the temporary transmission time (TempXmtTime).

Finally, the nodes that do not know the reserved resource information are the nodes.

Here, since one hop node among the competition nodes selected based on the three conditions is selected for time-base competition, one hop node among the competition nodes selected according to the three conditions is called a subframe-level competition Node (S505).

The communication node 300 first performs a mesh selection algorithm for time-base competition considering only subframe-level competing nodes (S506).

The mesh selection algorithm is the algorithm used to determine the next transmission time in the OFDM-based TDMA wireless mesh network. The mesh selection algorithm is expressed as pseudocode as follows. This mesh selection algorithm is specified in IEEE 802.16-2004 Std . Mesh Election algorithm for time-base competition is defined as a subframe-level mesh election algorithm.

The subframe level mesh selection algorithm may input an identifier (MyNodeID) of the communication node 300, an identifier list (CompetingNodeIDList) of the contending nodes, and a temporary transmission time (TempXmtTime) of the communication node 300 as input values. The subframe level mesh selection algorithm is a principle in which the communication node 300 is selected only when the hash value of the communication node 300 is greater than the hash value of all the competing nodes (CompetingNodeIDList) by obtaining a hash value for each node . Otherwise, the communication node 300 is not selected. If the hash value of the communication node 300 is equal to the hash value of some competing nodes, the temporary transmission time (TempXmtTime) is odd and the identifier (MyNodeID) of the communication node 300 is larger than the identifier of the contending node The communication node 300 is not selected when the temporary transmission time (TempXmtTime) is even and the identifier (MyNodeID) of the communication node 300 is smaller than the identifier of the contending node. If the communication node 300 is not selected for the temporary transmission time TempXmtTime at step S507, the temporary transmission time TempXmtTime of the communication node 300 is incremented by one at step S508, To S505) a subframe level mesh selection algorithm (S506). In this manner, selection of the contending node and execution of the sub-frame level mesh selection algorithm are repeated until the communication node 300 is selected.

When the communication node 300 is selected in the subframe-level mesh selection algorithm (S507), each node corresponding to two of the competing nodes of the communication node 300 transmits the node corresponding to its one- The subchannel-level competition node is selected by performing the subframe level mesh selection algorithm described above (S509). That is, in this step, the nodes corresponding to two of the competing nodes perform their respective sub-frame level mesh selection algorithms, and the selected two-hop competing node selects the subchannel-level ) Competition node.

If two sub-frame-based mesh selection algorithms are performed for two-hop competing nodes, it is possible to distinguish which two-hop competing nodes participate in frequency-axis competition, Thereby reducing the uncertainty and increasing the selection probability in the frequency axis competition of the communication node. However, this may result in a very small collision probability. If there is a requirement that does not permit even very small collisions, it is possible to omit the subframe mesh selection algorithm and define all two-hop competing nodes as subchannel-level competing nodes.

The communication node 300 has a subchannel-level competing node for each subchannel to perform a mesh selection algorithm for frequency-axis competition (S510). The mesh selection algorithm for frequency-axis competition is defined as a subchannel-level mesh selection algorithm. At this time, the communication node 300 selects subchannel-level nodes other than the nodes having the bitmap of the corresponding subchannel of 0, satisfying the first condition of the competing node selection among its own and subchannel-level competing nodes, level sub-channel-level mesh selection algorithm with competing nodes. That is, when the bitmap of the corresponding subchannel satisfies the first condition of the competing node selection and the bitmap of the subchannel is 0, it means that the corresponding subchannel is not reserved at the temporary transmission time (TempXmtTime), so that the subchannel- Are excluded from the competing nodes of the selection algorithm. The mesh selection algorithm at this stage is also the same as the above-described mesh selection algorithm, and is used instead of the temporary transmission time and frequency (TempXmtTimeFreq) considering both the temporary transmission time point (TempXmtTime) and the target subchannel. Here, TempXmtTimeFreq can be expressed by Equation (7).

&Quot; (7) &quot;

TempXmtTimeFreq = NoSubchannel * TmepXmtTime + Subchannel number

In Equation (7), NoSubchannel denotes the number of subchannels of one subframe, and the subchannel number indicates the number of subchannels when performing a subchannel-level mesh selection algorithm for each subchannel. That is, the temporary transmission time point and the frequency (TempXmtTimeFreq) are values considering both the time axis and the frequency axis.

When the communication node 300 is selected in the subchannel-level mesh selection algorithm (S511), the communication node 300 determines that the temporary transmission time TempXmtTime at that time is the next transmission time NextXmtTime S512). In this case, the communication node 300 can be selected for a plurality of subchannels, and if the communication node 300 is selected for a plurality of subchannels, the communication node 300 selects a subchannel among the selected subchannels The number of subchannels that can be simultaneously reserved can be arbitrarily selected.

When the next transmission time NextXmtTime is determined (S512), the communication node 300 calculates the parameters Exp and Mx from the next transmission time NextXmtTime and sets the reservation information of the selected subchannel as a bitmap S513).

In order to transmit the reserved resource information of the communication node 300 as well as the reserved resource information of one hop nodes to one hop nodes, the time difference (RxFwdTimeDiff) between the time of receiving the reservation resource information of one hop node and the time of transmitting the reservation resource information of one hop node, (S514).

The communication node 300 calculates the parameters (Exp, Mx, RxFwdTimeDiff) of the communication node 300, the parameters (Exp, Mx) of the calculated communication node 300 and the reservation information of the subchannel expressed by the bitmap, The reservation information of the subchannel of one hop node is transmitted to one hop nodes (S515). Here, the parameter (Exp, Mx) of one hop node transmits the value received from one hop node as it is.

Meanwhile, when the communication node 300 performs a subchannel-level mesh selection algorithm with a subchannel-level competing node for each subchannel, the communication node 300 selects a subchannel- (TmepXmtTime) is incremented by 1 (S508), the above process is repeated from the competitive node selection step (S504).

In this manner, the communication node 300 increases the temporary transmission time (TempXmtTime) by one until it is selected for at least one (or a required number) of subchannels in the subchannel-level mesh selection process, Repeat the above procedure from the selection process.

 The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, Such an embodiment can be readily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (20)

In a connection control method in a communication node of a wireless mesh network of an orthogonal frequency division multiple access scheme,
Receiving information of the next transmission time of one hop node and two hop nodes through the one hop node,
Calculating a next transmission interval of the one-hop node and the two-hop node using the next transmission time information of the one hop node and the two hop nodes,
Determining a subframe and a subframe corresponding to a next transmission time using the next transmission interval of the one hop node and the two hop nodes,
And transmitting information of the next transmission time to its one hop node
Lt; / RTI &gt; The method of claim 1,
Wherein the receiving comprises:
Receiving first and second parameters of the one-hop node and first to third parameters of the two-hop node,
The next transmission interval of the one hop node is calculated by the following equation
ReceiveTime + 2 ^Exp * Mx < = Next Transmission Period < ReceiveTime + 2 ^Exp * (Mx + 1)
Lt; / RTI &gt;
The next transmission interval of the two-hop node is calculated by the following equation
ReceiveTime + 2 ^Exp * Mx + RxFwdTimeDiff ≤ Next transmission interval <ReceiveTime + 2 ^Exp * (Mx + 1) + RxFwdTimeDiff
&Lt; / RTI &gt;
Wherein the first, second, and third parameters correspond to Exp, Mx, and RxFwdTimeDiff, respectively, and the ReceiveTime indicates a time when the first to third parameters are received. 3. The method of claim 2,
Wherein the step of transmitting information of the next transmission time to the one-
Calculating the first parameter and the second parameter corresponding to the next transmission time of the communication node, and
And sending the first and second parameters to the one-hop node of its own. 4. The method of claim 3,
Wherein the calculating the first parameter and the second parameter comprises:
Determining the first parameter according to at least one of a system setting value, a service quality and a priority, and
And calculating the second parameter using the determined first parameter and the next transmission time. 3. The method of claim 2,
Wherein the step of transmitting information of the next transmission time to the one-
Obtaining the third parameter from the time difference between the time of receiving the first and second parameters of the one hop node and the time of transmitting the first parameter and the second parameter of the communication node,
And transmitting the first to third parameters of the one hop node to the one hop node. The method of claim 5,
Wherein the step of transmitting information of the next transmission time to the one-
When the minimum value of the next transmission interval of the one hop node is earlier than the time of transmitting the first parameter and the second parameter of the communication node, the step of not transmitting the first to third parameters of the one hop node Further comprising: The method of claim 1,
Wherein the step of transmitting information of the next transmission time to the one-
And setting information of a subchannel corresponding to the next transmission time as a bitmap and transmitting the information. The method of claim 1,
Wherein the determining comprises:
Selecting a contending node to participate in a competition of a subframe resource with itself using a next transmission interval of the one hop node and two hop nodes,
Determining a subframe to be transmitted next using a next transmission interval of one hop node of the competing nodes,
Selecting a subchannel level competing node to participate in a competition of a subchannel resource with the subchannel to be transmitted next, and
Determining a subchannel to be transmitted next using the next transmission interval of the subchannel level contention node for each of all subchannels of the subframe to be transmitted next. 9. The method of claim 8,
Wherein the step of selecting the contending node comprises:
Among the one-hop node and the two-hop node,
Wherein the next transmission interval of the one hop node and the two hop node includes a first condition including a temporary transmission time of the communication node,
A second condition that a sum of a minimum value of a next transmission interval of the one hop node and two hop nodes and a holdoff time that the one hop node and the two hop node can not transmit is smaller than a temporary transmission time of the communication node,
A third condition in which the information at the next transmission time is unknown,
Selecting a node satisfying at least one of the plurality of contention nodes as the contention node. The method of claim 9,
The step of selecting the subframe level contention node comprises:
Further comprising changing the holdoff time according to at least one of a density, a delay condition, a resource period and a quantity of a communication node in the wireless mesh network. 9. The method of claim 8,
Wherein the step of determining a subframe to be transmitted next comprises:
And performing a mesh selection algorithm using one hop node of the contending node and the target subframe. 12. The method of claim 11,
Wherein the step of selecting the subchannel level competing node comprises:
Performing its own mesh selection algorithm with one hop node of each of its two hop nodes for each of the two hop nodes of the competing nodes, and
And selecting the two-hop node selected by the mesh selection algorithm as the subchannel level competing node. 9. The method of claim 8,
Wherein the step of determining a subchannel to be transmitted next comprises:
And performing a mesh selection algorithm using the subchannel level contention node, the target subframe, and the subchannel for each of the subchannels of the subframe to be transmitted next. The method of claim 13,
Wherein performing the mesh selection algorithm comprises:
The remaining subchannel level competing nodes, excluding the subchannel-not-reserved nodes, satisfy the condition that the next transmission interval of the subchannel-level competing node includes the temporary transmission time of the communication node, Performing the mesh selection algorithm using the mesh selection algorithm
Lt; / RTI &gt; In a connection control apparatus of a communication node in a wireless mesh network of an Orthogonal Frequency Division Multiple Access scheme,
A transmission time point for determining a subframe and a subchannel corresponding to a next transmission time point of the communication node using the next transmission interval of the one-hop node and the two-hop node, Decision part, and
A plurality of parameters used for expressing a next transmission interval of the communication node from a next transmission point of the communication node and transmitting the plurality of parameters to one hop node of the communication node;
And a connection control unit. 16. The method of claim 15,
Wherein the information transmitter comprises:
A first parameter of the plurality of parameters is determined in accordance with a system setting value or a service quality, and a first parameter of the plurality of parameters is calculated using the first parameter, the time of transmitting the plurality of parameters, 2 Connection control device for calculating parameters. 17. The method of claim 16,
An information receiving unit for receiving first and second parameters indicating a next transmission time point of the one hop node from the one hop node,
Further comprising:
Wherein the information transmitter comprises:
Acquiring a third parameter from a time difference between a time point at which the first and second parameters of the one hop node are received and a time point at which the plurality of parameters of the communication node are to be transmitted, With the plurality of parameters. The method of claim 17,
Wherein the information receiver comprises:
And receives the first to third parameters of the two-hop node together with the first and second parameters of the one hop node from the one hop node,
The next transmission interval of the one hop node is calculated by the following equation
ReceiveTime + 2 ^Exp * Mx < = Next Transmission Period < ReceiveTime + 2 ^Exp * (Mx + 1)
Lt; / RTI &gt;
The next transmission interval of the two-hop node is calculated by the following equation
ReceiveTime + 2 ^Exp * Mx + RxFwdTimeDiff ≤ Next transmission interval <ReceiveTime + 2 ^Exp * (Mx + 1) + RxFwdTimeDiff
/ RTI &gt;
The first to third parameters correspond to Exp, Mx and RxFwdTimeDiff, respectively,
Wherein the ReceiveTime corresponds to a time point at which the first to third parameters of the two-hop node are received. 16. The method of claim 15,
The transmission time determination unit may determine,
Selecting one of the competing nodes to compete with the other node using the next transmission interval of the one hop node and the two hop nodes and selecting one of the competing nodes as a subframe level competing node to participate in the competition of subframe resources, Determines a sub-frame to be transmitted next through an algorithm,
And a subchannel level competing node to participate in a competition of a subchannel resource with the two hop nodes of the competing node in the subframe to be transmitted next, And determines a subchannel to be transmitted next through a mesh selection algorithm with a channel level competing node. 16. The method of claim 15,
And sets information of a subchannel corresponding to the next transmission time as a bitmap and transmits the information.

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