KR101598225B1 - Method ans apparatus for assigning time slots in wireless ad-hoc networks - Google Patents

Abstract

A time slot allocation method of a wireless ad hoc network according to the present invention is a method of allocating a time slot of a wireless ad hoc network, the method comprising the steps of: a first node searching for a plurality of neighboring second nodes; Transmitting information indicating a time slot to a plurality of second nodes by transmitting a command for requesting information on a time slot and information indicating a timing to receive information on the time slot; Receiving information on the timeslot from the plurality of second nodes based on information on the time slot received from the second node by the first node; And allocating a time slot.

Wireless, ad hoc, time slot, allocation, scheduling

Description

[0001] METHOD AND APPARATUS FOR ASSIGNING TIME SLOTS IN WIRELESS AD-HOC NETWORKS [

The present invention relates to a wireless ad hoc network and, more particularly, to a method and apparatus for allocating time slots in a TDMA-based wireless ad hoc network.

A method of assigning time slots in time division multiple access (TDMA) can be classified into a centralized method and a distributed method.

The centralized scheme is a method of assigning a time slot to each node based on the assumption that a root node (e.g., a coordinator, etc.) knows a global topology. A very large overhead is required to obtain a global topology in a wireless ad hoc sensor network. Furthermore, as the node moves, a lot of topology changes occur, so that the control nodes are burdened with much.

In consideration of this problem, a distributed technique has been proposed. In the distributed scheme, each node identifies a local topology between two hops and then distributes the time slot based on it. According to the scheduling method of the time slot, the distributed scheme can be detailed by a random slot selection scheme and a minimum slot selection scheme. The lander slot selection scheme is a method of confirming whether a node overlaps a time slot allocated to a node between two hops after selecting a random slot. Since the random slot is selected, the probability of overlap with neighboring nodes between two hops is small, so that the run time required for allocating time slots can be reduced. The minimum slot selection scheme is a method in which a node acquires a list of allocated slots of neighboring nodes between two hops, and then selects the smallest time slot among the unoccupied timeslots. This method can reduce the maximum number of slots (max_slot) since the nodes reserve a small time slot.

Performance for time slot allocation is evaluated as the maximum number of slots (max_slot) in the network and the run time required to allocate time slots of all nodes included in the network.

The centralized scheme can have the most efficient time complexity in terms of the maximum number of slots, but it can not be directly applied to a wireless ad hoc sensor network.

In addition, the lander slot selection scheme of the distributed scheme has a problem in that the maximum number of slots is increased because the random slot selection scheme randomly selects time slots within the maximum slot number range. When the selection width of the time slot is limited to [0, c], in the worst case, the maximum number of slots is c, and the probability that the node is allocated a relatively large time slot is increased compared to the minimum slot selection technique. On the other hand, the minimum slot selection scheme can have as much time complexity as the centralized scheme, but it takes a long time to run time.

Therefore, the landing slot selection scheme and the minimum slot selection scheme may cause conflicting results in terms of the maximum number of slots and the runtime. Therefore, in a method of assigning time slots, a method is required that can reduce the maximum number of slots and reduce the run time at the same time.

SUMMARY OF THE INVENTION The present invention provides a time slot allocation method and apparatus for a wireless ad hoc network capable of effectively reducing the maximum number of slots while drastically reducing the run time required for time slot allocation, It has its purpose.

It is another object of the present invention to provide a time slot allocation method and apparatus of a wireless ad hoc network which can greatly reduce the time required for confirming information on time slots occupied by neighboring nodes.

According to an aspect of the present invention, there is provided a method of allocating time slots in a wireless ad hoc network, the method comprising: allocating a plurality of neighboring nodes to a first node; Transmitting to the plurality of second nodes information indicative of a command for requesting information about a time slot and a timing for receiving a reply to the time slot from the first node; Receiving information on the timeslot from the plurality of second nodes based on information indicating a timing to receive the reply from the node; And allocating a time slot of the first node in consideration of the information.

The information indicating the timing to receive the reply may be information obtained by sequentially arranging a list of identifiers of the plurality of second nodes.

Wherein the step of generating the information indicating the timing to receive the reply includes the steps of performing modulo hashing on the identifiers of the plurality of second nodes and performing a modulo hashing if the hashed value does not overlap with the hashed value And generating information by sequentially arranging a list of identifiers of the second node when the hashed values are overlapped with each other.

Wherein the step of generating the information indicating the timing to receive the reply includes the steps of receiving the small values selected by the plurality of second nodes and selecting the second remainder theorem based on the Chinese remainder theorem Calculating a common solution having common values in common with each other, and including the same common solution in information indicating a timing to receive the reply of the plurality of second nodes.

The information on the timeslot may include information indicating a timeslot allocated to the second node and a node neighboring the second node.

The information on the timeslot may be information in which the information indicating the timeslot is coded in a bitmap format.

A node device of a wireless ad hoc network according to another aspect of the present invention is a node device that transmits and receives data to and from a neighboring node included in a wireless ad hoc network and searches for a plurality of neighboring second nodes, A scheduler for establishing a time slot for connection with the second node; a transceiver for transmitting and receiving a signal for communication in a wireless ad hoc network; And a signal processing unit for processing data from the management unit and the scheduler and a signal from the transmission / reception unit, wherein the scheduler includes: a command for requesting information on a time slot; and information indicating a timing to receive the information on the time slot Based on the information indicating the timing to receive the reply, transmits to the second node, Receives the information on the time slot, and sets the time slot of the first node in consideration of the information on the time slot.

The scheduler may generate information that sequentially arranges a list of the identifiers of the plurality of second nodes as the information indicating the timing to receive the reply.

Wherein the scheduler performs modulo hashing on the identifiers of the plurality of second nodes and performs a modulo hashing on the identifiers of the plurality of second nodes and sequentially generates a list of hashed values for the second node, Generates information indicating the timing to receive the reply, and generates information for sequentially arranging a list of identifiers for the second node with respect to a second node in which hashed values overlap, Information indicating the timing can be generated.

Wherein the scheduler receives a small value selected by each of the nodes from the plurality of second nodes and generates a common solution having common small values selected by the second node based on the Chinese remainder theorem And generate information indicating the timing to receive the reply including the same common solution to the plurality of second nodes.

The information on the timeslot may be information in which the time slots allocated to the second node and nodes neighboring the second node are encoded in a bitmap format.

Wherein the scheduler comprises: a signaling slot setting unit for setting a timing of the second node to which the time slot information is to be returned; and a time slot information setting unit for setting a timing of the time slot information for confirming the time slot information received from the plurality of second nodes An acknowledgment unit, and a time slot allocation unit for allocating time slots in consideration of the time slot information.

According to the time slot allocation method and apparatus of the wireless ad hoc network of the present invention, the time required for time slot allocation can be drastically shortened, and at the same time, the maximum number of slots can be effectively reduced.

Further, the present invention uses a signaling slot to identify information on a time slot occupied by neighboring nodes, thereby greatly reducing the time required for confirming information on a time slot occupied by neighboring nodes have.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. It will be obvious to those who have.

1 is an exemplary diagram of a wireless ad hoc network including a node device according to an embodiment of the present invention. Referring to FIG. 1, the wireless ad hoc network includes a plurality of node devices.

 In an exemplary embodiment of the present invention, a node device included in a wireless ad hoc network includes a full function device (FFD) and a reduced function device (RFD). In an embodiment of the present invention, in order to easily explain the operation of the node device according to the present invention, node devices provided in a wireless ad hoc network are referred to as a first node 10, a second node 21, 22, , And third node (31, 32, 33, 34).

The first node 10 searches for neighboring nodes (e.g., the second node 21, 22, 23), requests information about the timeslot, and information indicating timing to receive the information To the neighboring nodes (e.g., the second node 21, 22, 23). The first node 10 receives information on the timeslot from the neighbor nodes (e.g., the second node 21, 22, 23), and based on the received information, .

Wherein the second node (21, 22, 23) is a node neighboring the first node (10), and comprises a command for requesting information about the timeslot from the first node (10) (E.g., the third node 31, 32, 33, 34), identifies the timeslot assigned to itself and the neighboring nodes (e.g., the third node 31, 32, 33, 34) To the first node (10).

The third node 31, 32, 33, 34 is a node adjacent to the second node 21, 22, 23, and in particular, And is a node to which a time slot is allocated.

2 is a block diagram schematically illustrating a configuration of a first node device of a wireless ad hoc network according to an embodiment of the present invention. 2, a first node 10 according to an embodiment of the present invention includes a channel access manager 110, a scheduler 120, a signal processor 130, a memory 140, and a transceiver 150, .

The channel access manager 110 searches a plurality of neighboring second nodes 21, 22, and 23 through a discovery process. For example, the channel connection management unit 110 transmits a search message (e.g., "Hello Message") for searching for a node to a plurality of second nodes 21, Then, a response message (e.g., "Dest. Hello Message") transmitted as a response to the search message is received from the second nodes 21, 22 and 23, and neighboring second nodes 21, 23), thereby completing the device discovery.

When the device discovery of the channel access manager 110 is completed, the scheduling unit 120 allocates its own time slot using the time slot information request command and the signaling slot information.

The scheduling unit 120 includes a scheduling control unit 121, a signaling slot setting unit 123, a time slot information checking unit 125, and a time slot assigning unit 127.

The scheduling control unit 121 controls the operations of the signaling slot setting unit 123, the time slot information checking unit 125, and the time slot assigning unit 127.

First, the scheduling control unit 121 instructs the operation of the signaling slot setting unit 123 to allocate its own time slot. The signaling slot setting unit 123 generates a command (e.g., a time slot information request command) requesting information on the time slot (hereinafter, referred to as 'time slot information'), (Hereinafter, referred to as 'signaling slot information') for indicating timing to receive the time slot information from the base station apparatuses 22 and 23, that is, time slots for receiving signaling. The signaling slot setting unit 123 transmits the time slot information request command and the signaling slot information to the signal processor 130 and the memory 140.

The scheduling controller 121 refers to the timing of the signaling slot and instructs the time slot information checking unit 125 to operate at the timing at which the time slot information is received from the second node 21, The time slot information checking unit 125 checks the time slot information received from each of the second nodes 21, 22 and 23 and stores the checked time slot information in the memory 140.

Further, the scheduling controller 121 refers to the timing of the signaling slot to confirm that all the timeslot information has been received from the second nodes 21, 22, and 23, Indicate. The time slot allocation unit 127 identifies the time slot information for the second node 21, 22, and 23 stored in the memory 140, and allocates a time slot for data transmission. Then, the scheduling controller 121 provides the time slot to the channel access manager 110.

Preferably, the timeslot allocation unit 127 allocates time slots occupied by the second nodes 21, 22, and 23 and third nodes 31 and 32 adjacent to the second nodes 21, , 33, and 34), and assigns the smallest slot among the occupied time slots to a time slot for data transmission. For example, when the second node 21, 22, 23 occupies the 0, 1, 5 th time slot and the nodes neighboring the second nodes 21, 22, 23 When the nodes 31, 32, 33, and 34 occupy the 2nd, 4th, 7th and 8th time slots, the time slot assigning unit 127 assigns the time slots (I.e., the third slot) as a time slot for data transmission.

Furthermore, the channel connection management unit 110 receives the time slots allocated from the time slot assignment unit 127 and transmits the time slots to the second nodes 21, 22, and 23. For example, the channel connection management unit 110 may transmit the provided time slot to the second node 21, 22, 23 using an ANNOUNCEMENT frame.

The signal processor 130 generates a signal for communication with the nodes included in the wireless ad hoc network through spread spectrum processing and transmits a signal from the nodes provided in the wireless ad hoc network to the channel access manager 110. [ And the scheduling unit 120, as shown in FIG.

The transceiver unit 150 modulates the signal on the carrier frequency so as to transmit the signal from the signal processor 130 to the other node device, up-converts the modulated carrier onto the RF frequency, Lt; / RTI > In addition, the transceiving unit 150 extracts a signal for communication in order to receive information from the other node device, and amplifies the received signal to a predetermined level so that the information included in the received signal can be processed do.

The memory 140 stores data required to be stored while the channel connection management unit 110 and the scheduling unit 120 operate.

Meanwhile, the second node 21, 22, 23 according to an embodiment of the present invention receives the time slot information from the first node 10, checks the time slot information, . 3, the second nodes 21, 22, and 23 may include a channel connection management unit 210, a scheduling unit 211, a signal processing unit 215, a memory 216, and a transmission / 217).

The second node (21, 22, 23) is a node connected to the first node (10) and the third node (31, 32, 33, 34). Accordingly, the second nodes 21, 22, and 23 may include basic components for communication with the other node devices, that is, the connection management unit 210, the signal processing unit 215, the memory 216, . The basic components 210, 215, 216, and 217 for communication with the other node devices are not significantly different from the corresponding components of the first node device 10 shown in FIG. Thus, the functionality of the basic components 210, 215, 216, 217 for communication with the other node devices refers to the description of the components 110, 130, 140, 150 described above.

Meanwhile, the scheduling unit 211 included in the second-1 node 21 according to an embodiment of the present invention includes a signaling slot checking unit 213 for requesting and transmitting time slot information, (214).

The operation of the signaling slot confirmation unit 213 is controlled by the scheduling control unit 212. The signaling slot identifying unit 213 confirms the signaling slot information received together with receiving the requested time slot information, and confirms the timing with which the second-1 node 21 transmits the time slot information. The signaling slot validation unit 213 stores the determined timing in the memory 140 and provides the timing to the access channel management unit 210. [

The first node 10 may transmit the signaling slot information in various manners. Accordingly, the signaling slot validation unit 213 can confirm the timing of transmitting the time slot information in correspondence with the manner in which the first node 10 transmits the signaling slot information.

The timeslot information generating unit 214 generates time slot information for each of the time slots allocated to the current second-first node 21 and the neighboring nodes (e.g., the third-first node 31, The third-second node 32) confirms the time slot being used, and then generates time slot information including the confirmed time slots. For example, the time slot information may be information obtained by encoding the identified time slots in a bit map format. Further, the bitmap is composed of bits of a predetermined number (for example, the number of time slots required for communication between two ad hoc), and the current second-1 node 21 and the second-1 node 21 ) May be a value which is set to 1 in a bit corresponding to a time slot occupied by neighboring nodes. For example, when the current second-1 node 21 occupies the first timeslot (e.g., 0 slot) and the nodes neighboring the second-first 21 node (e.g., the third- (E.g., the third-second node 32) occupies the third and fourth timeslots (e.g., 2 and 3 slots), the bitmap may be set to 1011.

Meanwhile, the first node 10 may transmit the signaling slot information in various manners. Hereinafter, a method by which the first node 10 can transmit the signaling slot information will be described in detail. A method of confirming the timing of transmitting the time slot information after the second-1 node 21 receiving the signaling slot information receives the signaling slot information will be described.

The signaling slot establishing unit 123 packages the signaling slot information as an identifier of the second nodes 21, 22 and 23 (for example, IDs of the second nodes 21, 22 and 23) One information '. Hereinafter, such a method is referred to as an 'identifier sorting method'.

According to the identifier sorting method, for example, the identifier of the second-first node 21, the second-second node 22, and the second-third node 23 is composed of 2 bytes, and the value of the identifier is 13EF, A118 and 1CC0 and the order of the timing of the signaling slot information is aligned with the second-first node 21, the second-third node 23 and the second-second node 22, the signaling slot setting unit 123 sets the signaling slot information to a value (for example, 13EF 1CC0 A118) in which the identifiers of the nodes are arranged in the order of the timing.

In response, the signaling slot identification unit 213 of the second-1 node 21 confirms the values of the identifiers of the nodes included in the signaling slot information in the order of the timing. Then, it confirms the position at which the identifier corresponding to the current second-first node 21 is located, and confirms the timing to transmit the time slot information. For example, when a value obtained by arranging the identifiers of the nodes 21, 22, 23 in the order of the above timings is "13EF 1CC0 A118", it is confirmed that the identifier 13EF of the second- So that the timing to transmit the time slot information is set to be transmitted in the first time slot (e.g., 0 slot).

As an alternative to this, the signaling slot setting unit 123 may set the identifiers of the second nodes 21, 22, and 23 (for example, IDs of the second nodes 21, 22, and 23) The size of the identifiers of the nodes can be reduced by modulo hashing.

That is, the signaling slot setting unit 123 can generate the identifier of the hashed node through the operation of Equation (1). Hereinafter, such a method is referred to as 'sorting of hashed identifiers'.

NodeID _hashed = NodeID mod p

Here, the Node ID _hashed is a hashed node identifier, the Node ID is a node identifier, and p is a prime number.

For example, when the hashed node identifier is composed of 1 byte, the p (decimal value) may be set to 251, which is the largest prime number while being relatively smaller than 256.

When the modulo hashing operation is performed on the identifiers (13EF, A118, 1CC0) of the second nodes (21, 22, 23) described above to 251, the second-first node (21) ), The identifiers of the second and third nodes 33 and 33 are converted into 1 byte, and the identifiers of the nodes may be 83 76 81, respectively. In addition, under the above-mentioned condition, the signaling slot information includes a value (e.g., 83 81 76) of the identifiers of the nodes arranged in the order of the timing.

When the second nodes 21, 22, and 23 are 2 bytes in size, the signaling slot setting unit 123 may reduce the size of the signaling slot information to half through module hashing. However, the hashed node identifier value may be set equal, in which case a conflict may occur between the hashed node identifiers. Therefore, the signaling slot setting unit 123 distinguishes between the case where the collision does not occur and the case where the collision occurs between the hashed node identifiers, and is stored in different areas (for example, a modulo area and an identifier area). That is, the signaling slot setting unit 123 performs modulo hashing on the second nodes 21, 22, and 23, and if the same hashing value does not occur, uses the hashed value as an identifier of each node Generates signaling slot information, and includes it in the modulo area. On the other hand, when the same hashing value is generated, the signaling slot information is generated using the identifier of each node as it is, and is included in the identifier field.

In response, the signaling slot identifying unit 213 of the second-first node 21 performs hashing on the identifier of the current node based on the modulo hashing described above. And confirms whether the identifier of the current node hashed in the modulo region of the signaling slot information exists. If there is an identifier of the hashed current node, it is checked how many times the identifier of the hashed current node is located to check the timing to transmit the time slot information. On the other hand, when the identifier of the hashed current node does not exist in the modulo area, the signaling slot check unit 213 checks the identifier area to find the position of the identifier of the current node, .

Furthermore, as an alternative to the 'ordering of the identifier sequence' and the 'ordering of the hashed identifiers', the signaling slot setting unit 123 generates signaling slot information including a predetermined integer value, and outputs the generated signaling slot information To all of the second nodes (21, 22, 23). Hereinafter, such a method is referred to as a "common identification method".

Specifically, the signaling slot setting unit 123 receives the small values selected by the second nodes from the second nodes 21, 22, and 23, respectively, and transmits the received values based on the extended euclidean algorithm And calculates a common solution having the small values in common with each other. The signaling slot setting unit 123 generates the signaling slot information including the calculated common solution.

On the other hand, the signaling slot check unit 213 of the second-1 node 21 receiving the same small value receives the common value and the small value selected by the current node from the Chinese remainder theorem) to calculate the time slot value. That is, the time slot value is confirmed by performing an operation on Equation (2) below.

TimeSlot _signaling = (x mod m _j ) -1

Here, TimeSlot _signaling indicates a signaling slot value, x indicates a common solution received from the first node, and m _j indicates a small value selected by the current node.

For example, when the small values selected by the second-first node 21, the second-second node 22 and the second-third node 23 are 7, 3, and 10, respectively, 10 generates a signaling slot information including the common solution by calculating a common solution 163, and transmits the signaling slot information. The signaling slot identifying unit 213 of the current node, i.e., the second-first node 21, can set the signaling slot to one slot through the calculation of Equation (2). Further, the signaling slot identifying unit 213 of the second-second node 32 and the second-third node 33 sets the signaling slots to 0 and 2 slots, respectively, through the calculation of Equation (2).

When the signaling slot is set through the 'common identification method' as described above, the size of the signaling slot information can be remarkably reduced. However, since the signaling slot setting unit 123 must perform the modulo arithmetic operation and the multiply arithmetic operation on the second nodes 21, 22 and 23, an operation for this operation is required. Therefore, if the number of the second nodes is large, the signaling slot setting unit 123 may be burdened with the calculation process. As a result, it is preferable that the signaling slot setting unit 123 generates the signaling slot information through the 'common identification method' only when the number of the third nodes is within a predetermined number (for example, five).

Hereinafter, a description will be given of the operation of the elements included in the node device, and the procedure of the time slot allocation method of the wireless ad hoc network according to the embodiment of the present invention will be described.

4 is a flowchart illustrating a procedure of a time slot allocation method of a wireless ad hoc network according to an embodiment of the present invention.

The first node 10, the second-first node 21, the second-second node 22, and the second-third node 23 of FIG. 4 correspond to the first node 10, -1 node 21, the second-second node 22, and the second-third node 23, respectively. Therefore, the first node 10, the second-first node 21, the second-second node 22, and the second-third node 23 of FIG. 4 have the same identification codes as those of FIG.

First, the channel connection management unit 110 of the first node 10 searches for a plurality of neighboring second nodes 21, 22, and 23 through a discovery process (operation 510). That is, the channel connection management unit 110 of the first node 10 transmits a search message (e.g., "Hello Message") for searching for a node. The second node 21, 22, or 23 transmits a response message (e.g., "Dest. Hello Message") including the address of the first node 10 that transmitted the search message, To the first node (10). Accordingly, the channel connection management unit 110 of the first node 10 receives the response message from the second node 21, 22, 23 through the transceiver unit 150 and the signal processor 130, The presence of neighboring second nodes 21, 22, and 23 is confirmed.

When the step 510 is completed, in order to check the time slots occupied by the plurality of second nodes 21, 22, 23 and the nodes neighboring the second nodes 21, 22, 23, 10 transmits a request for two-hop neighbors' slots (RFS) message to a plurality of second nodes 21, 22, and 23 (step 520).

Specifically, the channel connection management unit 110 of the first node 10 receives the response message and requests the scheduling unit 120 to allocate a time slot. Then, the scheduling controller 121 of the scheduling unit 120 instructs the signaling slot setting unit 123 to operate. The signaling slot setting unit 123 generates a command (e.g., a time slot information request command) requesting information on the time slot (hereinafter, referred to as 'time slot information'), (Hereinafter, referred to as 'signaling slot information') for indicating the timing to receive the time slot information from the base stations 22 and 23, that is, time slots for receiving signaling. The signaling slot setting unit 123 transmits the time slot information request command and the signaling slot information to the signal processor 130 and stores the information in the memory 140. Accordingly, the signal processor 130 transmits the RFS message including the time slot information request command and the signaling slot information to the second node (21, 22, 23) through the transceiver unit (150).

Each of the second nodes 21, 22, and 23 receiving the RFS message checks the signaling slot information included in the RFS message, and determines the time slot being used by each node and the time slot being used by the neighboring node And returns the timeslot information to the first node 10 in a signaling slot corresponding to its own node.

Specifically, the channel connection management unit 210 included in the second-1 node 21 receives the RFS message through the transceiver unit 350 and the signal processor 330, and the scheduling controller 211 of the scheduler 211 Lt; RTI ID = 0.0 > 212 < / RTI > In response to this, the signaling slot identifying unit 213 of the scheduling unit 211 checks the signaling slot information received together with receiving the requested time slot information, Confirm the timing to transmit time slot information. The identified signaling slot information is provided to the signal processing unit 330.

When the confirmation of the timing to transmit the time slot information is completed, the scheduling control unit 212 instructs the operation of the time slot information generation unit 214. The time slot information generation unit 214 generates a time slot information for each of the time slots allocated to the current second-first node 21 and the neighboring nodes (e.g., the 3-1 node 31 ) 3-2 node 32) confirms the time slot being used, and then generates time slot information including the confirmed time slots. The time slot information may be transmitted through a Two-hop Neighbors' Slots (TNS) message.

For example, the time slot information may be information obtained by encoding the identified time slots in a bit map format. Further, the bitmap is composed of bits of a predetermined number (for example, the number of time slots required for communication between two ad hoc), and the current second-1 node 21 and the second-1 node 21 (For example, the 3-1 node 31 and the 3-2 node 32 in FIG. 1) neighboring to the time slot occupied by the time slot occupied by the time slot occupied by the time slot. For example, when the current second-1 node 21 occupies the first timeslot (e.g., 0 slot) and the node neighboring the second-1 node 21 ), 3-2 node 32) occupies the third and fourth timeslots (e.g., 2 slots and 3 slots), the bitmap may be set to 1011.

The time slot information confirmed through the operation as described above is provided to the signal processing unit 330. The signal processing unit 330 transmits the TNS message to the transmitter 350 through the transmitter 350 based on the confirmed signaling slot information. 1 node (step 531).

The second-second node 22 and the second-third node 23 perform the same operation as the above-described operation of the second-one node 21, so that the time slot information To the first node 10 (steps 532 and 533).

On the other hand, the first node 10 receiving the TNS message sequentially in the signaling slot allocates its own time slot in consideration of the time slot information of the second nodes 21, 22, step).

Specifically, the scheduling controller 121 of the first node refers to the timing of the signaling slot, and at the timing at which the time slot information is received from the second nodes 21, 22, (125) to operate. The time slot information confirmation unit 125 sequentially receives the time slot information of the second nodes 21, 22, and 23 through the signal processor 130. Then, a time slot encoded in the form of a bitmap is confirmed in the received time slot information, and a node (e.g., a node) adjacent to the second node (21, 22, 23) The third node 31, 32, 33, 34) identifies the currently occupied time slot and stores it in the memory 140 sequentially. When the confirmation of the time slot information for the second node (21, 22, 23) is completed, the scheduling control unit (121) instructs the operation of the time slot allocation unit (127). The time slot assigning unit 127 identifies the timeslot information for the second nodes 21, 22, and 23 stored in the memory 140, and selects one of the unused timeslots, i.e., Assigns a lower number of time slots to its own time slot.

The time slot allocated through the above process is provided to the channel connection management unit 110. The channel connection management unit 110 transmits the allocated time slot to the signal processor 130 and the transmission / To the nodes 21, 22, and 23 (step 550). For example, the timeslot may broadcast an ANNOUNCEMENT frame to the second node (21, 22, 23).

Hereinafter, experimental examples of the time slot allocation method and apparatus of the wireless ad hoc network as described above will be described.

Comparative Example 1, Comparative Example 2 and Example 1 were tested using an ns-2 simulator.

In the comparative example 1, a node device of the wireless ad hoc network is set up by the DRAND (Distributed Randomized) method which is one of the minimum slot selection methods.

In the comparison example 2, the start point and the end point of the FPRP (Synchous method), which is one of the random slot selection methods, are known, and the node device of the wireless ad hoc network is set by measuring the time slot.

In the first embodiment, a node device is set up based on a centralized randomized (CRAND) method of a wireless ad hoc network according to the present invention. When the number of the second nodes is five or less, , And when the number of the second nodes is more than five, the signaling slot information is set to be generated as a 'sorting method of hashed identifiers'.

In this experiment, we increased the number of nodes from 50 to 250 in a randomly generated multi-hop network, and the transmission rate of the node was set to 40 kbps like C1000 RF.

5 is a graph showing an average run time according to a size between two neighboring hops according to an experimental example of the present invention as log values. Referring to FIG. 5, it can be seen that Comparative Example 2 exhibits the fastest performance, Experimental Example 1 is the next fastest, and Comparative Example 1 takes much time.

Compared to the first embodiment, the second embodiment requires a perfect time synchronization between the nodes and can not completely eliminate the collision of the time slots although the speed is fast because it is a method of selecting a random slot .

The first comparative example has the advantage of not requiring time synchronization between the nodes as in the first embodiment, but has a disadvantage that the run-time performance is very poor.

FIG. 6 is a graph showing logarithm of a result of a maximum time slot according to an experimental example of the present invention. Referring to FIG. 6, the first comparative example and the first embodiment have a maximum time slot having almost the same value, and the complexity is O (? 2). On the other hand, the maximum time slot of the comparative example 2 is theoretically unconstrained, and the experimental result is twice as large.

As a result, it can be seen that the embodiment 1 greatly reduces the runtime required for the allocation of time slots while maintaining the maximum time slot size at the same level as that of the existing maximum technique.

The method and apparatus according to the present invention may be embodied as computer readable code on a recording medium readable by digital equipment and apparatus. The recording medium readable by the digital equipment and the apparatus includes all kinds of recording apparatuses in which data that can be read by the digital equipment and apparatus system is stored. Examples of the recording medium that can be read by the digital equipment and the apparatus include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical disk and the like and also implemented in the form of a carrier wave (for example, . In addition, the recording medium readable by the digital equipment and the apparatus can be distributed and distributed in a network-connected digital equipment and a device system, and can be stored and executed by a digital equipment and a device-readable code in a distributed manner.

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, and that various modifications and changes may be made by those skilled in the art.

1 is an exemplary diagram of a wireless ad hoc network including a node device according to an embodiment of the present invention,

2 is a block diagram schematically showing the configuration of a first node device of a wireless ad hoc network according to an embodiment of the present invention;

3 is a block diagram schematically illustrating a configuration of a third node device of a wireless ad hoc network according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a procedure of a time slot allocation method of a wireless ad hoc network according to an embodiment of the present invention;

FIG. 5 is a graph showing an average run time according to the sizes of two neighboring hops as log values according to an experimental example of the present invention;

FIG. 6 is a graph showing a logarithmic value of a maximum time slot according to an experimental example of the present invention. FIG.

Claims (12)

A method for allocating time slots in a wireless ad hoc network, Searching for a plurality of neighboring nodes of the first node, Transmitting information indicating a time slot to which the first node requests information on a time slot and information indicating a timing to return information on the time slot to the plurality of second nodes; Receiving information on the timeslot from the plurality of second nodes based on information indicating a timing to receive the reply from the first node; And allocating a time slot of the first node in consideration of information on the time slot received by the first node from the second node. 2. The method according to claim 1, wherein the timing information indicating the timing to receive the reply, Wherein the list of identifiers of the plurality of second nodes is information obtained by sequentially arranging lists of identifiers of the plurality of second nodes. The method as claimed in claim 1, wherein the step of generating information indicating the timing to receive the reply comprises: Performing modulo hashing on the identifiers of the plurality of second nodes; Generating information by sequentially arranging a list of hashed values when the hashed values do not overlap; And generating information for sequentially arranging a list of identifiers for the second node when the hashed values are overlapped with each other. The method as claimed in claim 1, wherein the step of generating information indicating the timing to receive the reply comprises: Receiving a plurality of small values selected by a plurality of the second nodes; Calculating a common solution having common small values selected by the second node based on a Chinese remainder theorem; And including the same common solution in information indicating a timing to receive the reply of the plurality of second nodes. 5. The method of any one of claims 1 to 4, And information indicating a time slot allocated to a node neighboring the second node and the second node. 6. The method of claim 5, wherein the information on the timeslot is information in which the information indicating the timeslot is coded in a bitmap format. A node apparatus for transmitting and receiving data to and from a neighbor node included in a wireless ad hoc network, A channel access manager for searching for a plurality of neighboring second nodes and managing connections with the plurality of second nodes, A scheduler for setting a time slot for connection with the second node; A transmitting and receiving unit for transmitting and receiving a signal for communication in a wireless ad hoc network, And a signal processing unit for processing data from the channel connection management unit and the scheduler and signals from the transmission / reception unit, The scheduler comprising: And transmitting information indicating a timing to receive the information on the time slot to the second node, Receives information on the timeslot from the plurality of second nodes based on information indicating a timing to receive the reply, and sets a timeslot of the node device in consideration of information on the timeslot A node device of a wireless ad hoc network. 8. The apparatus of claim 7, wherein the scheduler comprises: And generates information that sequentially arranges a list of the identifiers of the plurality of second nodes as information indicating timing to receive the reply. 8. The apparatus of claim 7, wherein the scheduler comprises: Performing modulo hashing on the identifiers of the plurality of second nodes, Generating information for sequentially indicating a list of hashed values for a second node for which the hashed value is not duplicated, And generates information indicating a timing to receive the reply by generating information for sequentially arranging a list of identifiers for the second node for a second node in which hashed values are duplicated, Lt; / RTI > 8. The apparatus of claim 7, wherein the scheduler comprises: Receiving a small value selected by each node from the plurality of second nodes, Calculating a common solution having common small values selected by the second node based on the Chinese remainder theorem, And generates information indicating the timing to receive the reply including the common solution to a plurality of the second nodes. 11. A method according to any one of claims 7 to 10, Wherein the time slot allocated to the second node and the neighboring node to the second node is information encoded in bitmap form. 11. The method according to any one of claims 7 to 10, A signaling slot setting unit for setting a timing of the second node to which the time slot information is to be returned, A time slot information checking unit for checking the time slot information received from the plurality of second nodes based on the timing; And a time slot allocator for allocating a time slot in consideration of the time slot information.

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