KR20140120973A - Method and apparatus for channel access of multi-user voice communication in wireless sensor network - Google Patents

Abstract

Disclosed is a method and device for scheduling a channel for voice communications in a wireless sensor network. The method for scheduling a channel confirms a channel access state according to a data transmission request for voice communications of a terminal and delays a frame transmission cycle or a slot transmission cycle depending on the confirmed channel access state. After that, a slot for transmitting data is allocated, and, therefore, data can be transmitted without the waste of channels.

Description

[0001] The present invention relates to a channel scheduling method and apparatus for voice communication in a wireless sensor network,

The present invention relates to a wireless sensor network, and more particularly, to a channel scheduling method and apparatus for increasing frequency band utilization efficiency so that voice communication can be performed in real time between a plurality of wireless sensor networks.

The IEEE 802.15.4 standard basically uses a contention-based channel access scheme, but supports a GTS (Guaranteed time slot) mode to ensure periodic data transmission. However, GTS mode can only assign up to 7 slots, which guarantees stability in non-contention periods and limits the number of users that can periodically transmit data to a maximum of 7 users. This limitation can not provide a proper communication environment when more than seven users want to periodically transmit data.

Also, since the GTS mode is a method in which a specific user periodically occupies one GTS slot, even if a user occupying the GTS slot stops data transmission, there is a limit that another user can not use the GTS slot immediately. As a result, if the number of users in a wireless sensor network is large, the channel utilization rate is rapidly decreased. Also, since the transmission period of the beacon is controlled by an exponential increase of the minimum transmission period (15.36 ms), it is also impossible to set the beacon period to any desired period. As a result, there is a problem that it is not suitable for voice communication in which data is generated every 20 ms in the wireless sensor network.

The present invention provides a channel scheduling method and apparatus for increasing the efficiency according to the use of a frequency band so as to enable real-time voice communication among a plurality of users in a wireless sensor network.

It is another object of the present invention to provide a channel scheduling method and apparatus capable of improving the channel utilization rate by minimizing the interval between voice data frames and improving the communication stability by guaranteeing a fixed transmission interval allocation between users .

According to an aspect of the present invention, there is provided a channel scheduling method for improving efficiency in frequency band utilization so that real-time voice communication can be performed between a plurality of users in a wireless sensor network, and a recording medium recording a program for performing the method.

According to an embodiment of the present invention, there is provided a method for controlling access to a terminal, comprising: (a) confirming a channel access state according to a data transmission request for voice communication of a terminal; And (b) allocating a slot for data transmission after delaying a frame transmission period or a slot transmission period according to the identified channel access state.

In the step (b), if the channel access state is idle, a slot for data transmission may be allocated after the data transmission is delayed during the frame transmission period.

In the step (b), when the channel access state is busy, the data transmission is delayed in units of the slot transmission period, and when the channel access state is confirmed as the idle state, a slot for data transmission can be allocated.

In the step (b), when the channel access state is busy, if the number of channel access attempts exceeds the maximum number of channel access attempts, it is determined that there is no space to allocate a new slot in the frame, As shown in FIG.

According to another aspect of the present invention, there is provided a channel scheduling apparatus that increases efficiency according to use of a frequency band so as to enable real-time voice communication between a plurality of users in a wireless sensor network.

According to an embodiment of the present invention, there is provided a terminal device comprising: a status verifying unit for verifying a channel access state according to a data transmission request for voice communication of a terminal; And a scheduler for allocating a slot for data transmission after a delay of a frame transmission period or a slot transmission period according to the identified channel access state.

The channel access state may be either an idle state or a busy state.

If the channel access state is the idle state, the scheduler may allocate a slot for data transmission after delaying the data transmission for the frame transmission period.

The scheduling unit may allocate a slot for data transmission after delaying data transmission during the slot transmission period if the channel access state is busy.

When the channel access state is busy, the scheduling unit may not allocate a slot for data transmission when the number of channel access attempts exceeds the maximum number of channel access attempts.

From the time when the data transmission request is received until the end of the frame transmission period in which the data transmission request is received and the next frame transmission period starts.

The channel scheduling method and apparatus for voice communication in a wireless sensor network according to an embodiment of the present invention can increase the efficiency of frequency band use so that real-time voice communication can be performed among a plurality of users in a wireless sensor network .

In addition, the present invention can improve the channel utilization rate by minimizing the interval between voice data frames, and secure the transmission interval allocation between users to improve communication stability.

Brief Description of the Drawings Fig. 1 is a diagram for explaining a general CSMA-CA based frame structure. Fig.
2 is a diagram illustrating a frame transmission period and a slot transmission period;
3 is a diagram illustrating a conventional data transmission method.
4 is a block diagram schematically illustrating an internal structure of a channel scheduling apparatus according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating a channel scheduling method according to an embodiment of the present invention; FIG.
6 and 7 are diagrams for explaining channel scheduling according to an embodiment of the present invention;

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may 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 another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The present invention relates to a channel access method capable of maximizing a channel utilization rate by transmitting data by delaying a frame transmission period or a slot transmission period according to a channel access state after confirming a channel access state in data transmission of a wireless sensor network . Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view for explaining a general CSMA-CA based frame structure, FIG. 2 is a diagram for explaining a frame transmission period and a slot transmission period, FIG. 3 is a diagram for explaining a conventional data transmission method Fig.

As shown in FIG. 1, a frame in the CSMA-CA mechanism is divided by a beacon (becon) transmitted to a network, and one frame can be divided into 16 slots having the same size. As shown in FIG. 1, one frame has a contention area and a contention-free area. Each beacon frame is allocated a slot in a contention area and a contention-free area, and transmits data through the allocated slot.

As shown in FIG. 2, one frame has an interval of about 20 msec, and each slot has a period of 1,15 to 1.68 msec. That is, when a user is allocated a slot for data transmission, data can be transmitted through the corresponding fixedly allocated slot for each frame transmission period.

For example, as shown in FIG. 3, data can be received using a slot allocated at a time of a data transmission request for each frame transmission period (i.e., a frame interval).

A beacon frame is generally used for synchronization of devices in general, but a voice communication channel access method operating in a non-beacon mode (non-beacon mode) will be described in detail herein.

FIG. 4 is a diagram schematically illustrating an internal configuration of a channel scheduling apparatus according to an embodiment of the present invention. Referring to FIG.

4, the channel scheduling apparatus 400 includes a status checking unit 410, a scheduling unit 415, a communication unit 420, a memory 425, and a control unit 430.

The state checking unit 410 is a means for checking and outputting a channel access state according to a data transmission request of an arbitrary terminal. For example, the state checking unit 410 can check a channel access state in units of slot transmission periods. Here, the channel access state may be an idle state or a busy state.

The idle state in the present specification means an idle state in which data is not transmitted through a corresponding channel at the time when an arbitrary terminal requests data transmission.

In the busy state, a channel is assigned a slot for fixed data transmission when a terminal requests data transmission, and a channel is occupied through the corresponding slot.

For example, the state checking unit 410 checks the channel access state according to a certain data transmission request, and if the channel access state is busy, the state checking unit 410 checks the channel access state in units of the slot transmission period, You can see when changes are made.

The scheduling unit 415 receives the channel access state through the state checking unit 410 and transmits the data requested to be transmitted according to the channel access state without a delay or delays the data in units of a frame transmission period or a slot transmission period, Is a means for scheduling. In this specification, the term 'data transmission is delayed during the frame transmission period' means that the data transmission is delayed until the end of the frame transmission period when the data request is received from the terminal (that is, the start time of the next frame transmission period).

For example, if the channel access state input through the state checking unit 410 is idle, the scheduling unit 415 delays data transmission in units of a frame transmission period, and then allocates a slot to a channel. More specifically, the scheduling unit 415 determines whether the number of channel connection attempts during idle time is equal to or greater than the maximum number of channel connection attempts when the channel access state received through the state checking unit 410 is idle.

In the present specification, the maximum number of channel connection attempts at idle time can be calculated using a frame transmission period and a transmission interval (Tx interval).

The scheduling unit 415 can calculate the maximum number of channel connection attempts in idle state using Equation (1).

Here, Tx interval represents a slot transmission interval, and frame period represents a frame transmission period.

If the channel access state is idle, the scheduling unit 415 increments the number of channel access attempts by a predetermined size (for example, 1), updates the frame by a predetermined number of frame transmission cycles, and assigns a slot to a channel can do. At this time, if the channel access state is the idle state and the data transmission request is the initial transmission request, the scheduling unit 415 transmits the data requested to be transmitted without delay, Slots can be allocated and the data can be scheduled to be transmitted in a fixed manner. However, if the channel access state is idle or there is a slot occupying a fixed channel, the number of channel access attempts is increased, and the data transmission is delayed in units of one frame transmission period. Then, a slot is allocated on the channel, May be scheduled to be transmitted.

However, if the channel access state input through the state checking unit 410 is in the busy state, the scheduling unit 415 delays the data transmission in units of the slot transmission period, When the access state is input, a slot may be allocated at that time and the data may be scheduled to be transmitted.

For example, the scheduling unit 415 determines whether the number of channel access attempts exceeds the maximum number of channel access attempts when the channel access state input through the state checking unit 410 is busy. If the number of channel access attempts exceeds the maximum number of channel access attempts, the scheduling unit 415 does not transmit data because all the slots are allocated to the channel and the data can not be transmitted. In this way, when the data transmission fails, the scheduling unit 415 may transmit a guidance message according to the data transmission failure to the terminal.

However, if the number of channel access attempts is less than the maximum number of channel access attempts, the scheduling unit 415 increases the number of channel access attempts by a predetermined size (for example, 1) and then delays the data transmission by the slot transmission period The data transmission can be scheduled according to the channel access state inputted through the post-condition checking unit 410. [

The communication unit 420 is a means for transmitting and receiving data with other devices (e.g., a terminal, etc.).

The memory 425 stores various applications, algorithms, and the like necessary for operating the channel scheduling apparatus 400 according to an embodiment of the present invention. The memory 425 also stores various status information and variables for channel scheduling (for example, the number of idle channel access attempts, idle maximum channel access attempts, channel access attempts, maximum channel access attempts, etc.) .

The controller 430 controls the internal components of the channel scheduling apparatus 400 according to an embodiment of the present invention such as the state checking unit 410, the scheduling unit 415, the communication unit 420, the memory 425 ), And the like).

FIG. 5 is a flowchart illustrating a channel scheduling method according to an embodiment of the present invention. FIGS. 6 and 7 are diagrams for explaining channel scheduling according to an embodiment of the present invention. Referring to FIG.

Each step to be described below is performed by an internal component of the channel scheduling apparatus, but will be collectively referred to as a channel scheduling apparatus 400 in order to facilitate understanding and explanation. Hereinafter, a method for scheduling channel access by the channel scheduling apparatus 400 after receiving a data transmission request from an arbitrary terminal will be described.

In response to the data transmission request from any terminal, the channel scheduling apparatus 400 confirms the channel access state in step 510. For example, the channel scheduling apparatus 400 may perform a clear channel assessment (CCA) to check a channel access state for whether a channel can be acquired. Here, the channel access state may be either an idle state or a busy state.

In step 515, the channel scheduling apparatus 400 determines whether the channel access state is an idle state.

If the channel access state is the idle state, the channel scheduling apparatus 400 determines in step 520 whether the number of channel access attempts at idle exceeds the maximum number of channel access attempts at idle.

If the number of channel access attempts at idle is equal to or less than the maximum number of attempted channel access attempts at idle, the channel scheduling apparatus 400 allocates slots in the frame at step 525 and schedules the data to be transmitted.

The maximum number of channel access attempts during idle is a value obtained by dividing a data transmission period by a frame transmission period as shown in Equation (1), that is, a state in which a frame is in an idle state and a data transmission request is received In this case, the channel scheduling apparatus 400 can schedule a slot to allocate a slot in the frame and directly transmit data.

However, if the number of channel access attempts at idle exceeds the maximum number of channel access attempts at idle, the channel scheduling device 400 increases the number of channel access attempts at idle by a predetermined amount at step 530 and updates the channel access attempts.

Then, in step 535, the channel scheduling apparatus 400 delays the data transmission during the frame transmission period. The channel scheduling apparatus 400 then proceeds to step 510. In this manner, the channel scheduling apparatus 400 checks the channel access state, delays the data transmission during the frame transmission period if it is in the idle state, checks the channel access state, confirms slot assignment according to the channel access state, . ≪ / RTI >

Referring to FIG. 6, it is assumed that a fixed slot is allocated in units of a frame transmission period, as shown in 610 of FIG.

In this state, when data transmission is requested from an arbitrary terminal to an idle state in which a frame is not allocated a slot as in 615, conventionally, a slot is allocated at that time to transmit data. Accordingly, in the conventional method, if a channel access state is idle on the basis of a time point when data transmission is requested from a terminal in one frame, a slot can not be allocated in a frame and a resource is wasted there is a problem.

6, the channel scheduling apparatus 400 may delay the data transmission during the frame transmission period (step 620) even if the channel access state is requested to be idle (i.e., when the slot is not allocated) And allocate a post-slot to transmit the data (625 in Fig. 6).

If it is determined in step 515 that the channel access state is busy, in step 540, the channel scheduling apparatus 400 delays the data transmission during the slot transmission period.

In step 545, the channel scheduling apparatus 400 confirms the channel access state. As described above, the channel scheduling apparatus 400 can check the channel access state by performing the CCA.

In step 550, the channel scheduling apparatus 400 confirms whether the channel access state is an idle state as a result of checking the channel access state.

If the channel access state is the idle state, the channel scheduling apparatus 400 allocates slots and transmits data in step 555. [

However, if the channel access state is not the idle state, the channel scheduling apparatus 400 determines in step 560 whether the channel access attempt count exceeds the maximum channel access attempt count.

If the number of channel access attempts is equal to or less than the maximum number of channel access attempts, the channel scheduling device 400 increases the number of channel access attempts by a predetermined amount in step 565 and updates the channel access attempts. And then proceeds to step 540.

However, if the number of channel access attempts exceeds the maximum number of channel access attempts, the channel scheduling apparatus 400 determines that an idle channel can not be allocated due to all slots allocated to the channel in step 570, do.

7 shows an embodiment of scheduling a channel when the channel access state is busy. 7, it is assumed that one fixed slot is allocated in a frame, as in 710 of FIG. At this time, when a data transmission request is received from an arbitrary terminal at a time when a slot is allocated as shown in 715 of FIG. 7, the channel scheduling device 400 performs a CCA to check a channel access state. Since a fixed slot is allocated at a time point 715 in FIG. 7, the channel access state is checked as a busy state as a result of performing the CCA. If the channel access state is busy, the channel scheduling apparatus 400 delays the data transmission during the slot transmission period and performs the CCA to reaffirm the channel access state. If the channel access state is the idle state, Slots to allocate and schedule data to be transmitted.

Meanwhile, the channel scheduling method according to an exemplary embodiment of the present invention may be implemented in the form of a program command that can be executed through a variety of means for electronically processing information, and may be recorded in a storage medium. The storage medium may include program instructions, data files, data structures, and the like, alone or in combination.

Program instructions to be recorded on the storage medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of software. Examples of storage media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, magneto-optical media and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as devices for processing information electronically using an interpreter or the like, for example, a high-level language code that can be executed by a computer. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

400: Channel scheduling device
410:
415: scheduling unit
420:
425: Memory
430:

Claims (11)

A state checking unit for checking a channel access state according to a data transmission request for voice communication of a terminal; And
And a scheduler for allocating a slot for data transmission after delaying the frame transmission period or the slot transmission period according to the determined channel access state.
The method according to claim 1,
Wherein the channel access state is one of an idle state and a busy state.
3. The method of claim 2,
The scheduling unit may include:
And allocates a slot for data transmission after delaying data transmission during the frame transmission period when the channel access state is idle.
3. The method of claim 2,
The scheduling unit may include:
Wherein the controller allocates a slot for data transmission after delaying data transmission during the slot transmission period if the channel access state is busy.
5. The method of claim 4,
The scheduling unit may include:
Wherein when the channel access state is busy, a slot for data transmission is not allocated if the number of channel access attempts exceeds a maximum channel access attempt count.
The method according to claim 1,
Wherein the frame transmission period includes:
Wherein the data transmission request is transmitted from a time point when the data transmission request is received until a time point at which the data transmission request is received and the next frame transmission period starts.
(a) checking a channel access state according to a data transmission request for voice communication of a terminal; And
(b) allocating a slot for data transmission after a delay for a frame transmission period or a slot transmission period according to the identified channel access state.
8. The method of claim 7,
The step (b)
And if the channel access state is idle, allocating a slot for data transmission after delaying data transmission during the frame transmission period.
8. The method of claim 7,
The step (b)
Wherein the data transmission is delayed by the slot transmission period when the channel access state is busy and a slot for data transmission is allocated when the channel access state is identified as the idle state.
8. The method of claim 7,
The step (b)
When the channel access state is in the busy state and the number of channel access attempts exceeds the maximum number of channel access attempts, it is determined that there is no space to allocate a new slot in the frame, and a data transmission failure is notified to the terminal Channel scheduling method.
A recording medium on which a program for performing the channel scheduling method according to any one of claims 7 to 10 is recorded.

Images