KR101731654B1 - Media Access Control Method for macro-cell based M2M network and its appratus therof - Google Patents

Abstract

The present invention relates to a macrocell M2M network medium access control method and an M2M device using the same.
The macrocell M2M network medium access control method according to an exemplary embodiment of the present invention receives information on an access point (an access point) that controls the wireless network and the wireless network through a broadcast channel of a wireless network to which the object communication device attempts to access Requesting a connection using a random access in a contention access period of a first frame period of the wireless network using the received information, receiving a response to the access request from the access point, The method comprising the steps of: receiving information on a contention free period that can be used exclusively by the object communication device in the wireless network; and when it is necessary to transmit aperiodic first traffic to the AP, Using a random access in a contention access interval of 2 frames And performing the first traffic transmission.

Description

[0001] The present invention relates to a macro-cell M2M network medium access control method and a M2M device using the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a macrocell M2M network medium access control method and an M2M device using the same, and more particularly to a technique for medium access control of a device communication device in a macrocell network operating at a low duty cycle.

There are various kinds of communication such as M2M (machine to machine communication), MTC (machine type communication), IoT (Internet of Thing), smart device communication, object intelligence communication or machine oriented communication . Object communication refers to all communication methods in which communication is performed without a person intervening in the communication process. On the other hand, the object communication has various patterns of communication depending on the market, application, or service to be used. In particular, object communication does not always require communication to be connected, and information to be transmitted and received may be transmitted and received with a certain pattern, and data may be transmitted and received without a pattern. In the object communication having these characteristics, it is necessary to perform efficient networking according to the characteristics of the object communication entity or the characteristics of the function to be provided by the object communication entity. Particularly, in a macro-cell in which devices performing large-scale object communication are combined, efficient media access control (MAC) control considering low power consumption and low duty cycle of the object communication device ), But it is currently not presented in the object communication in the object communication.

The present disclosure relates to medium access control for a macro-cell machine-to-machine communication (M2M) network, and particularly to support a large scale object communication device operating at a low duty cycle.

That is, the present invention proposes a MAC frame structure having uplink and downlink competitive free intervals and a common contention access period with a plurality of time slots, and provides a MAC frame structure for a plurality of object communication devices, It supports the transmission of non-periodic and urgent traffic through the access section. A medium access control method for a macro cell network that operates at a low duty cycle and which can provide large-scale access point access and low-delay traffic transmission of object communication devices by supporting transmission of such periodic / aperiodic traffic, .

According to an embodiment of the present invention, there is provided a macro-cell M2M network medium access control method for an object communication device, the method comprising: Access point), requesting a connection using a random access in a contention access period of a first frame period of the wireless network using the received information, Receiving a response to the connection request and information on a contention free period that the object communication device can use exclusively in the wireless network, A contention access in the second frame period of the wireless network Using a random access between a step of performing the first traffic transmission.

According to another aspect of the present invention, there is provided a macro-cell M2M network medium access control method, comprising: transmitting information of an access point (AP) for controlling a wireless network and a wireless network through a broadcast channel of a wireless network; The method comprising the steps of: receiving, from a subject communication device, a message relating to a transmission of a message or a traffic request requesting a connection using a random access in a contention access period of one frame period; A contention free period that can be used exclusively by the object communication device in the wireless network, and when the received message is a message related to traffic transmission, Periodic < / RTI > And a step of transmitting a response to the traffic.

The object communication device according to another embodiment of the present invention includes a receiver for receiving a signal transmitted in a wireless network, a transmitter for transmitting a signal to the wireless network, and a controller for controlling the receiver and the transmitter, Wherein the receiving unit controls the object communication device to receive information of an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of a wireless network to which the object communication device attempts to access, The control unit controls the transmission unit to request a connection using a random access in a contention access period of a first frame period, and the control unit causes the receiving unit to transmit a response to the connection request from the AP, The object communication device can be used exclusively Wherein the control unit controls the AP to receive information on a contention free period when the non-periodic first traffic is transmitted to the AP, The control unit controls the receiving unit and the transmitting unit to perform the first traffic transmission.

According to another aspect of the present invention, an access point includes a receiver for receiving a signal transmitted in a wireless network, a transmitter for transmitting a signal to the wireless network, and a controller for controlling the receiver and the transmitter, Wherein the transmitter transmits information of an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of the wireless network, and the receiver receives a contention access period of a first frame period of the wireless network Wherein the controller controls to receive a message by using the random access through the wireless communication network when the received message requests a connection, To transmit information on the contention free period (Contention Free Period) Wherein the control unit controls the transmitting unit to transmit a response to the aperiodic traffic transmitted by the object communication device included in the message when the received message is a message related to traffic transmission .

The macrocell M2M network media access control method according to another embodiment of the present invention determines the type of the data to be transmitted and the control traffic to be transmitted, in which the M2M device accesses the AP through the wireless link and is allocated a traffic channel A traffic determining step of selecting a transmission channel for the identified traffic, a traffic transmitting step of transmitting the corresponding traffic through the selected transmission channel, and a releasing of the connection of the AP with the M2M device, which is no longer valid, And a connection releasing step.

As described above, in this specification, a dedicated time slot is shared by a plurality of object communication devices in a low-duty-cycle macrocell network in a time division manner, and a transmission channel for non-periodic data is shared between a wake- It is possible to simultaneously accommodate large scale object communication devices that significantly exceed the number of dedicated time slots and to support rapid bidirectional transmission of various traffic associated with any object communication device, There is an effect that the efficiency of the medium access control for the duty communication object communication device is increased.

Figure 1 is a diagram illustrating the operation of M2M devices coupled to a macrocell M2M network to which one embodiment of the present disclosure is applied.
2 is a diagram showing a control structure of a medium divided into a contention access period and a contention free period.
3 is a diagram illustrating a configuration of a MAC frame for a macrocell M2M network according to an embodiment of the present invention.
4 is a diagram illustrating an initial connection step according to an embodiment of the present invention.
5 is a diagram illustrating a case where a dedicated traffic channel for non-periodic traffic is allocated according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating a case where a dedicated traffic channel for non-periodic traffic is allocated according to another embodiment of the present invention.
7 is a diagram illustrating a medium access control process supporting a large number of M2M devices in accordance with one embodiment of the present disclosure.
FIG. 8 is a diagram illustrating a process in which the object communication device performs medium access control in a macro-cell network according to an embodiment of the present invention.
FIG. 9 is a diagram illustrating a process in which the object communication device performs medium access control when the AP transmits aperiodic traffic in an embodiment of the present invention.
10 is a diagram illustrating a process of controlling a wireless network in an AP so that the object communication device performs medium access control in a macro cell network according to an embodiment of the present invention.
11 is a diagram illustrating a process of controlling a wireless network in an AP so that the object communication device performs media access control in a macro cell network according to another embodiment of the present invention.
FIG. 12 is a diagram illustrating a configuration of an object communication device and an AP for controlling a wireless network according to an embodiment of the present invention.
13 is a diagram illustrating a medium access process according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals whenever possible, even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

In this specification, object communication is mainly described. As mentioned above, M2M, MTC, IoT, smart device communication, object oriented communication, and object function communication are divided into various fields, and M2M is mainly described in this specification. However, this description is not limited to M2M, but it is applicable to all systems and structures providing inter-device communication, i.e., object communication, and communication occurring in these systems.

Figure 1 is a diagram illustrating the operation of M2M devices coupled to a macrocell M2M network to which one embodiment of the present disclosure is applied.

The present specification can be applied to a network in which large-scale M2M devices exist, but can also be applied to a network in which small-scale M2M devices exist. However, in the present specification, the description will be focused on a large-scale application in a macro cell where the effect is greatly exerted.

1, a large number of M2M devices 111, 112,..., 150, 151, and 199 scattered over a wide range are operated in a single access point (AP) .

Various M2M network technologies may be used depending on wireless coverage to provide remote monitoring and control services for a certain area of people / objects. The macrocell M2M network covers a wider area than a typical M2M network where the wireless coverage of the M2M device is up to 100m. The AP 100 shown in FIG. 1 can support many M2M devices 111-199, which have wireless coverage up to several Km and operate with a significantly lower duty cycle.

Since typically M2M devices coupled to one AP 100 operate with a low duty cycle, tens or hundreds of thousands of M2M devices within the coverage of one AP 100 can be accommodated. The M2M device herein includes various sensor nodes that support communication for sensors and actuators. Also, since each M2M device in the M2M network can support different applications, the AP can simultaneously provide various application services mixed in the cell. Typical application services that can be provided by M2M network include remote meter reading such as gas / electric / water service, remote check of the open / closed status of the valuables storage, remote updating of object information such as business cards, and weather / to be. Such an application service is characterized by generating a small amount of data from several tens of minutes to several hours, several days, even months, and requires a relatively long data transmission period than a general communication device. Therefore, an M2M device that uses a battery for energy efficiency must operate with a very low duty cycle. At the same time, data and control commands must be transmitted to the application service server or M2M device in a timely manner without delay. Therefore, in order to provide high-quality service in such a macro cell sensor network and M2M network, a medium access control method for a large-scale M2M device operating at a very low duty cycle is required.

As a method for using a wireless medium, CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance), devices detect a carrier of a network, and when the network is empty (data is not transmitted) It waits for a predetermined time (Back-off time) according to its appointed order or location, and then sends the data. CSMA / CA means that data is transmitted by confirming data transmission parts of other devices in a wireless zone that anyone can access, and there is a kind of competition in using wireless resources. On the other hand, there is no competition when the area of radio resources that can be used in advance is allocated to each device.

Hereinafter, a period in which devices compete and perform / control a medium access is referred to as a contention access period (CAP), and a period during which devices perform / control media access without competition is referred to as a contention free period, Or competition free interval). In the following embodiments, the CSMA / CA will be described as a random access scheme in a contention access period, but the present invention is not limited thereto, and various random access schemes including CSMA / CA can be applied.

2 is a diagram showing a control structure of a medium divided into a contention access period and a contention free period. FIG. 2 shows the structure of a frame 200. A frame is called a super frame and can be composed of a plurality of slots having a predetermined size.

As a medium access control method for network connection, the contention access period 220 and the contention free period 230 can be distinguished as shown in FIG. A contention access period 220 in which a collision is allowed and a contention free period 230 in which a contention is not allowed and is not allowed to be allowed are active periods in which data transmission is possible. Meanwhile, sections 201 and 202 for transmitting a beacon or the like may be present in the frame to identify the network. The beacon interval is the time between successive two beacon frames and can be determined as 2 ^BO by the beacon order (BO, Beacon Order). The length of the active period can be determined as 2 ^SO by the superframe order (SO). In the configuration of the frame of FIG. 2, the active period including the beacon period always has 16 time slots regardless of the superframe order.

Although not shown in the figure, an inactive period corresponding to the sleep mode may also exist in the frame of FIG. Hereinafter, the operation of the competitive access period and the non-contention period will be described.

The contention free interval 230 of the superframe of FIG. 2 is composed of seven time slots. Unlike the contention access period 220 in which connection delays and data transmission delays due to connection competition between nodes (devices) exist, this interval 230 is constituted by time slots that can be used entirely by a specific node. That is, the 230 interval of FIG. 2 may be configured as a GTS (Guaranteed Time Slot) composed of one or more slots, and since there are seven slots, a GTS can be allocated to a maximum of seven nodes. Of course, if three or two slots are allocated, the number of nodes that can be allocated may be reduced. In the case where the active period has a fixed length and the number of timeslots of the contention free period 230 is less than 7, the contention access period 220 is increased by the reduced portion of the contention free period 230 Time slots.

When media access control is applied to devices as shown in FIG. 2, it is possible to support a device having a low duty cycle. However, if all M2M devices connecting to an AP, a coordinator, or the like have the same wakeup schedule in which the active and inactive modes are repeated at the same time, even if the active period has 16 time slots, The active period in the cycle operation mode is limited to a period proportional to the duty cycle and is allowed as a valid communication period for transmission of various data of the M2M device. Therefore, an M2M device operating at a low duty cycle can not transmit data quickly because it can not occupy a wireless link immediately when data is generated. In addition, since the number of M2M devices occupying the wireless link is limited in the corresponding interval due to the short active period, and since a plurality of M2M devices attempt to access simultaneously in the active period, especially in the competing access period 220, May occur. As a result, the M2M device can not immediately acquire the wireless link, or even if the wireless link is occupied, data transmission is delayed due to frequent transmission attempts of other M2M devices. Therefore, such a medium access control method does not efficiently support many M2M devices.

Thus, for a large amount of M2M devices operating at low duty cycles, a medium access control method for a macrocell M2M network that allows various traffic to be transmitted within a delay time according to a service QoS and simultaneously provides a large scale connection of such M2M devices Is required.

3 is a diagram illustrating a configuration of a MAC frame for a macrocell M2M network according to an embodiment of the present invention.

The MAC frame 300 of FIG. 3 includes an uplink 320 and a downlink 310, which are many timeslots, to support a TDMA / TDD scheme as a multiple access scheme. , 330). The downlinks 310 and 330 include a broadcast period for providing various general and control information on the AP and the wireless channel. According to an embodiment of the present invention, a broadcast channel (BCH) A frame control channel (FCCH), a radio link control channel (LCCH), and an access feedback channel (AFCH). Of course, the plurality of channels constituting the broadcast section may be added or changed in implementing the embodiments of the present invention.

 The first time slot of the broadcast section 315 is a broadcast channel (BCH), which provides attribute information about the AP and additionally provides a paging function. The paging function is provided by using a list of receiving node IDs as one piece of broadcast information for notifying the receiving node that traffic has been received by the AP. In addition, the broadcast message also reports whether the FCCH message has been changed and whether the LCCH message has been changed.

The second time slot of the broadcast interval 315 is a frame control channel (FCCH), and is used to broadcast information on the MAC frame structure to all M2M devices in a cell (AP Cell) controlled by the AP. The third timeslot of the broadcast interval 315 is used as a radio link control channel (LCCH) to broadcast information such as Random Access Parameters, control for AP cells and radio links. An access response channel (AFCH) constituting another broadcast section 335 is used for providing information necessary for AP connection to a specific M2M device or notifying the result of data reception. The information for the AP connection includes a traffic channel allocation history, an allocation ID, and the like for a specific M2M device. The allocation of the traffic channel and the M2M device ID can be performed by an existing method, but a separate mechanism for improving the management and operation efficiency may be applied. The corresponding slot for the connection response channel may be designated as the first slot of the downlink interval 330 starting from the uplink interval 320, and may have a length of two slots.

In FIG. 3, the broadcast interval 335 of the connection response channel is temporally separated from other channels of the other broadcast interval 315, and the random access results simultaneously attempted by many M2M devices through the corresponding time slot are broadcast Since it can easily provide a temporary time slot that can transmit it to an M2M device in sleep mode when non-periodic queries or control data is received.

The uplink interval 320 includes a contention access period 320 in which all M2M devices can randomly access and a contention free period 324 and 338 in which the M2M device can exclusively use the contention period.

The contention access period 322 of the uplink 320 supports the random access of the M2M device by the CSMA / CA scheme. In the contention access period 322, the M2M device may attempt to acquire a channel through a random back-off in a slot-based manner, and the contention access period 322 may allow a plurality of M2M devices to simultaneously and equally It is a section where connection can be attempted. The contention access period 322 is used by the M2M device initially for AP access and for aperiodic data transmission.

A traffic transmission period (traffic TX period, 324, 338) provides a traffic channel (TCH). Each of the traffic transmission periods 324 and 338 of the uplink 320 and the downlink 330 may have the same number of time slots, and each time slot is used as one traffic channel. Since the time slot of each link is unidirectional, one uplink time slot and one downlink time slot must be provided in pairs in order to transmit traffic in both directions as one traffic channel. A pair of time slots is assigned to the same slot number, i.e., a slot in the same position, in each section according to an embodiment of the present disclosure. In another embodiment of the present disclosure, time slots with different numbers may be assigned to M2M devices requiring fast response or fast bi-directional communication.

The MAC frame structure is continuously repeated in time order. A sequence number is applied to distinguish the repeated MAC frame time periods and is broadcast on the BCH of the broadcast period 315. [

Hereinafter, the medium access control process will be described.

Each step of the media access control process is performed interactively in the AP and M2M devices. In order to support reliable communication in the wireless link, it provides traffic transmission by the confirmation mode between two objects on the link. Traffic transmission in this specification means data transmission. That is, for the traffic transmitted through the MAC frame, the receiving object responds with the MAC frame corresponding to the ACK in order to confirm that the reception of the traffic is performed without error. In this case, if the receiver has extra traffic to be transmitted to the sender, the corresponding traffic to be separately transmitted through the MAC frame corresponding to the ACK can be transmitted. By doing so, the receiver can send traffic simultaneously with the response. This procedure has the effect of reducing the waiting time of the traffic to be transmitted.

In addition, since M2M devices use a low duty cycle, the traffic generation period, that is, the transmission interval of necessary traffic, is very low. Depending on the application, it may occur several times or several hours, several times a day. Moreover, because M2M devices can have limited energy such as batteries, it is necessary to maintain a sleep mode for most of the time, except when transmitting traffic, in order to maximize energy efficiency.

On the other hand, since the macro-cell M2M network supports a large-scale M2M device, it is not easy for the AP to smoothly manage all link connectivity to the M2M device connected thereto. Therefore, the M2M device can be implemented to have the validity for link connectivity, that is, responsible for link maintenance. Therefore, the M2M device activates at regular intervals in addition to traffic transmission and listens to various channels of the broadcast section.

Hereinafter, each step constituting the medium access control process will be described.

4 is a diagram illustrating an initial connection step according to an embodiment of the present invention.

In FIG. 4, consecutive 401 and 402 MAC frames are shown. In the initial access step, the M2M device 405 accesses the AP through a wireless link and receives a traffic channel. The M2M device 405 first receives the AP related information through the BCH of the broadcasting interval 415 of the 401 and also receives the MAC frame structure information and the random access information Random through the FCCH and the LCCH of the broadcasting interval 415 of the 401 Access information). The M2M device 405 that selected the AP to be connected generates a connection request message with the ID of the AP as the receiver.

The connection request message includes a temporary identifier (Temporary ID) selected for temporary use by the M2M device 405 to identify itself, and a data transmission period in which the M2M device 405 transmits its data to the AP at regular intervals . In addition, the connection request message includes a minimum wakeup period, which is an interval activated in a sleep state, in order to receive a broadcast message transmitted through a BCH and maintain synchronization with an AP. In a typical implementation, the data transfer cycle is much larger than the minimum wakeup period. However, according to another embodiment, if the data transmission period is equal to or less than the minimum wakeup period, the minimum wakeup period for the corresponding M2M device may not be designated separately. The minimum wake-up period is common to all M2M devices and can be set according to separate criteria taking into account the network environment. A minimum wake-up period applies to each M2M device, but does not mean simultaneous wake-up of all M2M devices. Also, the active state maintenance period of the M2M device according to the minimum wakeup period is usually limited to the BCH interval, but may be determined according to the contents of the received BCH broadcast message.

After setting the backoff window size and the backoff value using the random access information, the M2M device 405 sets the backoff window size and the backoff value in the range of the starting point of the RACH (Random Access CHannel) Attempt channel occupancy by CA. The channel occupation is made in the contention access section 422 of 401.

According to the CSMA / CA mechanism, the M2M device 405 waits for a set backoff interval and then evaluates whether the link is busy. If the link is clean, it sends the connection request message to the AP. If it is determined that it is busy, the M2M device 405 selects a new backoff value, waits for the set backoff interval, and then checks the link status again. If the link is still busy, then the M2M device 405 doubles the size of the backoff window. Then, the above process is repeated. Here, the backoff setting value is randomly selected in the [0, backoff window size] interval, and the value is equal to the number of timeslots.

The M2M device 405 may send the same MAC frame 402 to the same MAC frame 402 in order to continue the channel occupancy attempt in the contention access period 472 of the next MAC frame 402 if the communication is not completed within the competing access period of the current MAC frame 401. [ Off condition can be applied. The M2M device 405 performs a backoff operation as if all of the contention access sections of the MAC frames 401 and 402 are connected. For example, the backoff is continued in the new contention access period 472 following the backoff value remaining in the previous contention access period 422. As another example, if the backoff is completed in the previous contention access period 422, the new backoff value can be reset in the current contention access period 472 by the same condition.

The response to the connection request through the contention access period is provided through the AFCH of the broadcast section 485. [ 4 shows a case in which a response is provided through the AFCH of the broadcast frame 485 of 402 frames. If the connection request is accepted, the AP sends an M2M device ID along with an ACK response, and the number of uplink and downlink timeslots as its traffic channel. Upon receiving the connection response, the M2M device sets its uplink time slot to its traffic channel for transmission on the subsequently generated traffic.

The procedure of FIG. 4 is also used in the initial connection step, but can also be used when transmitting aperiodic traffic.

The traffic to be transmitted between the M2M device and the AP is largely periodic and irregular. In the traffic discrimination step, a traffic channel is selected so that necessary traffic can be normally transmitted according to the type of data to be transmitted and control traffic . As described above, the traffic provided by the AP and M2M devices is divided into two types, i.e., periodic traffic and aperiodic traffic.

Periodic traffic is traffic that is transmitted according to data transmission period such as generated data and status information and non-periodic traffic corresponds to alarm, query, data and information that should be temporarily transmitted at a time other than the data transmission period Traffic. These two types of traffic are transmitted through different traffic channels depending on the time of generation and transmission. Therefore, the traffic discrimination step is a step of discriminating a traffic type, that is, periodicity or non-periodicity, and selecting a channel to transmit the traffic. The determination of the traffic type is a process of determining whether the traffic to be generated or transmitted is periodic or aperiodic, and may be determined by the generation or transmission time of the traffic.

If data such as measurement and report data, query, control command, etc. exist at a time corresponding to a dedicated traffic channel for transmission / reception of the corresponding data, i.e., a time slot, it is determined as periodic traffic. Alternatively, if the traffic is a dedicated traffic channel, that is, a traffic temporarily present at a time point not corresponding to a time slot, it can be discriminated as aperiodic traffic.

The transport channel for periodic traffic is selected as a timeslot within the traffic transmission period of dedicated traffic channels, i.e., 324 and 328 in the case of FIG. This traffic channel is already known to both the M2M device and the AP, which is allocated in the initial access step shown in FIG. The M2M device receives its assigned traffic channel as a response message to the connection request, and the AP allocates a traffic channel and M2M device ID for the corresponding M2M device using a different method for a valid connection request, To know the traffic channel of a particular M2M device.

5 is a diagram illustrating a case where a dedicated traffic channel for non-periodic traffic is allocated according to an embodiment of the present invention.

As described above, the transmission channel for non-periodic traffic is selected and temporarily allocated to the dedicated traffic channel at a time when the dedicated traffic channel is already allocated and can not be used. This is selected by the AP or M2M device depending on the direction of traffic transmission (up or down). Reference numerals 510 and 530 denote downlink, and reference numeral 520 denotes an uplink section. The case of being selected in the M2M device will be described as follows. In the case of the M2M device 505, the non-periodic traffic is information that should be reported to the AP and the application service server without delay, such as an alarm or an emergency notification. When such data is generated, the M2M device immediately wakes up and listens for the BCH, FCH, and LCCH of the downlink broadcast section 510 (S550). Based on the received BCH 512, FCCH 514, and LCCH 516 messages, attempts to acquire the link for selecting the RACH in the contention access period 522 of the uplink 520 connected thereto (S555). At this time, the random access is performed in the same manner as the initial connection, but can be implemented to have a higher priority. Therefore, it is possible to provide an opportunity to occupy a specific RACH required for transmission relatively first than an M2M device that performs initial connection. The M2M device 505 of FIG. 5 may transmit information via the RACH occupied in S555. Whether the information transmitted through the RACH 522 is received or not can be implemented by checking the ACK value transmitted from the AP through the AFCH 535 of the corresponding frame period.

FIG. 6 is a diagram illustrating a case where a dedicated traffic channel for non-periodic traffic is allocated according to another embodiment of the present invention.

In the case of the AP 605, the non-periodic traffic is a query message requesting status information to the M2M device 603 or data to be transmitted intermittently, but without delay, such as a control command causing a desired operation. The AP determines when it can send the message to the corresponding M2M device 603, if it is generated or received. This means to select a MAC frame section in which data can be transmitted and to select a wake-up point of the M2M device that arrives the earliest through checking the wake-up schedule of the corresponding M2M device 603. The AP transmits a paging message notifying the corresponding M2M device 603 via the BCH 612 of the downlink 610 of that interval (S650). The transmitted paging message is received by the M2M device 603 as shown in step S652 and is also transmitted to the temporary traffic channel (s) 603, which the M2M device 603 can use to receive the data through the AFCH 635 of the MAC frame period 639, that is, information on the downlink time slot is received (S660, S662). The temporary traffic channel is selected from among empty time slots in the downlink traffic transmission interval 638 of the downlink 630 of the corresponding MAC frame period in a variety of methods and provides a temporary communication link with the M2M device as in S670 . The uplink through the ad hoc traffic channel can be selected as the uplink time slot of the same slot number as above. For example, in the uplink traffic transmission interval 644 of the uplink 640 of the next frame, the time slot 646 of the uplink traffic transmission interval 644 having the same slot number as the slot number received in S660, (603) may transmit traffic to the AP (605).

It is possible to perform the initial connection through the process of FIGS. 4, 5 and 6, or transmit the traffic by recognizing whether the traffic to be transmitted is periodic or non-periodic. That is, in the traffic transmission step, the corresponding traffic is transmitted through the selected channel for the identified traffic.

The periodic traffic uses the assigned traffic channel, i.e. uplink and downlink timeslots. Does not allow other M2M devices to occupy the same time slot at the same time through competition because a particular timeslot is exclusively assigned for a particular M2M device. Thus, data for any M2M device can be transmitted without delay through the dedicated traffic channel assigned to the M2M device. Thus, the M2M device transmits its data in a dedicated uplink timeslot and likewise the AP transmits data for the M2M device in a dedicated downlink timeslot of the specific M2M device.

This traffic transmission step can be operated in the acknowledged mode. For the transmitted data, the sender wants an ACK message or an ACK message including the data to be transmitted to the sender, if any. Therefore, the receiver must immediately transmit the message as a response. The traffic transmission is thus completely ended by exchanging the data frame with its response frame.

On the other hand, in the case of non-periodic traffic, transmission through the ad hoc traffic channel is performed in the same manner as above in the temporarily allocated uplink and downlink timeslots. In this case, the ACK message provided as a response by the receiving side is transmitted on the uplink in the next MAC frame period. However, transmission through the contention access interval is performed by transmitting data in the same manner as the access method using the RACH and receiving an ACK message as an acknowledgment in the AFCH of the same MAC frame period.

Finally, the disconnection step is a step of disconnecting the connection between the M2M device and the AP that are no longer valid according to the reason for disabling the wireless link. If the set radio link, that is, the traffic channel, is invalid, the radio link can no longer be maintained. Therefore, the link must be validated in order for the radio link to remain persistent. Therefore, each M2M device repeatedly and continuously checks the validity of its traffic channel using several methods. First, it confirms whether each channel of the broadcast section such as BCH is normal. It is checked whether there is a broadcast message in the channel listened to each time of wake up according to the wakeup schedule and whether the received broadcast messages are valid. Next, it is checked whether a dedicated traffic channel is occupied by another M2M device and whether there is channel interference exceeding a certain threshold value. Evaluation of the validity of the wireless link can also be performed at the AP. It is checked whether or not each M2M device transmits periodic traffic through its traffic channel, that is, the traffic of the corresponding M2M device is received at a predetermined interval in each time slot. The effectiveness of the wireless link is also assessed by the presence or absence of a response to the traffic transmission for a specific M2M device through the paging and ad hoc traffic channels.

If it is determined that the wireless link is valid and the traffic to be transmitted is generated through the process, the traffic discrimination step is performed. However, if it is determined that the wireless link is not valid, the M2M device or AP may retrieve and disconnect the traffic channel, i. E., The time slot assigned to the particular M2M device, through a series of messages or processes.

7 is a diagram illustrating a medium access control process supporting a large number of M2M devices in accordance with one embodiment of the present disclosure. 7 is performed with the interaction of M2M device 701 and AP 702 as described above. Therefore, it starts when the M2M device 701 wants to join the network and lasts indefinitely through the iteration of the configuration steps as long as the wireless link is maintained.

Any M2M device 701 that wants to join the network must establish a wireless link to act as a network member. The information transmitted between the M2M device 701 and the AP 702 in FIG. 7 refers to the information transmitted / received through the frames shown in FIGS. 3, 4, 5, 6, and the like. Therefore, an arrow between the M2M device 701 and the AP 702 indicates a flow of information included in a corresponding channel or slot of the frame. In the network, the AP 702 includes radio and AP information such as BCH, FCCH, and LCCH of a broadcasting interval of each frame period (S710, S711).

The unconnected M2M device 701 searches for the BCH of the downlink broadcast interval 315 of FIG. 3 and listens to the BCH, FCCH, and LCCH (S712). In the listening process, the BCH, FCH, and LCCH messages are sequentially received, and all information necessary for network connection, i.e., AP related information, MAC frame information, random access related information, and link control related information are checked. This information is also used for synchronized operation and communication with the network.

The M2M device 701 makes a connection request through random access using the RACH of the contention free period (S714). If the request is valid, the AP 702 allocates the dedicated traffic channel through the time division slot sharing method and allocates the node ID (S716). The allocation result including the allocation information is transmitted through the AFCH starting the downlink interval in the same MAC frame period (S718), thereby notifying the M2M device 701 that the connection request is normally accepted. In addition, the M2M device 701 confirms that the network connection is normally established by receiving it.

The time-sharing slot sharing method of step S716 allows the M2M devices to use specific timeslots at different time points in order to increase spectral efficiency, taking into consideration the data transmission interval of the M2M devices. With this method, the M2M device 701 can be provided with an exclusively usable time slot according to the data transmission period. For example, if the MAC frame number is 1, 2, 3, ..., the time slot can be assigned from 1 to 100, and the data transmission interval of the first M2M device corresponds to 3 MAC frame length, 3, 6, 9, .... 3n (n is an integer of 1 or more) MAC frame. On the other hand, if the data transmission interval of the second M2M device is also equal to 3 MAC frame length, it is possible to allocate 5 time slots of 1, 4, 7, ..., 3n + 1 (n is an integer of 1 or more) can do. In this case, the first and second M2M devices are allotted five timeslots, but since the MAC frames used are different from each other, each of the M2M devices can exclusively use the dedicated slot.

After a dedicated time slot has been assigned as a traffic channel, the M2M device 701 is activated in its time slot according to the transmission schedule by the data transmission period, and in the downlink broadcast interval in accordance with the wakeup schedule for listening to the broadcast and paging information (S720). It completes the connection, remains active, and supports periodic traffic and non-periodic traffic.

When periodic traffic occurs, the M2M device 701 transmits the traffic through the time slot in the allocated dedicated traffic transmission interval (S710). This traffic channel is already known to both the M2M device and the AP, which is allocated in the initial access step of step S716. Since the AP 702 knows the time slot of the dedicated traffic transmission interval of the M2M device 701, the AP 702 can receive the traffic transmission of the received M2M device 701 through the time slot.

If the M2M device 701 generates data requiring urgent transmission such as an alarm at a time other than the transmission schedule at step S730, the M2M device 701 immediately wakes up and the downlink broadcast (S732) and transmits the traffic to the AP 702 through a random access using the RACH (S734). The AP 702 confirms the transmitted traffic and generates an acknowledgment ACK (S736). Then, the AP 702 transmits an acknowledgment to the AP 702 over the AFCH of the same MAC frame period, and the M2M device 701 completes the traffic transmission by receiving the acknowledgment (S738).

On the other hand, if the AP 702 has data requiring urgent transmission such as a control command at a time other than the transmission schedule (S740), the AP 702 checks the wakeup schedule of the corresponding M2M device 701 In step S744, the M2M device 701 notifies the corresponding M2M device 701 of the traffic information in the waiting queue for transmission through the downlink broadcast channel of the MAC frame corresponding to the earliest wakeup time.

The M2M device 701 awakes from the sleep mode according to the wakeup schedule and receives the broadcast channel (S750). When the M2M device 701 includes paging to notify that the traffic received by the M2M device 701 is in the transmission waiting state in the AP 701, the M2M device 701 receives the channel of the remaining broadcasting interval, The frame structure and the radio link information are correct.

Meanwhile, the AP 702 selects a temporary traffic channel available for the transmission of the waiting traffic and transmits it to the corresponding M2M device 701 through the AFCH (S752). It is reasonable that the ad hoc traffic channel is operated for a time period in which the transmission of the urgent data can be completed and can be selected to be valid for at least two MAC frame intervals.

Since the M2M device 701 has confirmed the traffic to be received in step S750, it receives the temporary traffic channel information for itself by listening to the next AFCH (AFCH in step S752) (step S754). The temporary traffic channel information includes an uplink time slot number, a start time of the ad hoc traffic channel, and an expiration time (in units of a MAC frame period). The starting point of the ad hoc traffic channel may be a difference between the current MAC frame interval and the current MAC frame interval, and may have a value of 0 when it is the current MAC frame interval. Of course, it may be a MAC frame interval by a predetermined mechanism.

The AP 702 transmits the traffic through the temporary traffic channel, and the M2M device 701 receives the traffic through the temporary traffic channel (S760).

If the ad-hoc traffic channel is not the downlink time slot of the current MAC frame, the M2M device 701 transitions to the sleep mode, and then the AP 702 wakes up again in the selected MAC frame period to receive the traffic notified by the AP.

The assignment of the time slot, briefly described above, will now be described in more detail. The allocation of the time slot is performed by checking the overlap between the transmission schedule according to the data transmission period of the requested M2M device and the transmission schedule of another M2M device already assigned to the corresponding slot for each time slot. Here, the transmission schedule is a time series of periodicity in which data can be transmitted in a time slot. That is, it is a collection of time points that are woken up using the current MAC frame period as a reference time point. It is assumed that the transmission schedule of the M2M device 701 requested to be connected starts from the current MAC frame period. Therefore, at that point in time, the time slot at that point maintains the occupied state as busy. If it is confirmed that the transmission is overlapped, the transmission schedule of the requested M2M device 701 is considered to start from the next MAC frame period. The overlap checking is performed in the same manner as described above. If it is determined that the time slot can be used at all times, the process is repeated for the next time slot. If it is confirmed that the M2M device 701 is not overlapped, the M2M device 701 that is requested to be connected has a transmission schedule in which the time slot identified as the non-overlapping is allocated and the transmission time is set as the transmission time point.

For example, if five M2M devices are already assigned to a given time slot, they are assigned different transmission schedules {TS_i; i = 1, 2, 3, 4, 5}, and the M2M device newly requesting the connection has a transmission line of TS_r. The transmission schedule is composed of transmission time and transmission period as TB_i (j), TI_i, j = 0,1,2, ..., and transmission time is a unit of MAC frame interval, It is the remaining time until the data transmission is possible. The transmission time TB_r (j) of TS_r is always the comparison target time. That is, it means transmission from the MAC frame period to be subjected to the overlap checking. The transmission time is decremented by 1, the value of TI-1, and j represents the order of MAC frames in chronological order. Therefore, the overlap checking is performed by TS_r and {TS_i; i = 1, 2, 3, 4, 5}. If the result is determined to be overlapping, the comparison time point is changed to the next MAC frame period, and the transmission schedule of TS_r, that is, the transmission time point is updated as TB_r (j) = j. If the transmission periods are different, the comparison and update are sequentially repeated over a period corresponding to their maximum common multiple. If it is determined that there is no overlap at j = n, then the M2M device requesting the connection is assigned the time slot as the traffic channel and the transmission schedule TB_r (n) = n is assigned at the transmission time. Thus, it is possible to support M2M devices with many timeslots.

AP can periodically generate and broadcast a beacon frame, which is a kind of broadcast channel that supports synchronous mode operation for switching the periodic active / inactive state of each M2M device to improve energy efficiency and network life of all network M2M devices. Can be performed. When receiving the beacon frame including such broadcast information, the M2M devices illustrated in FIG. 7 can use a contention access interval of an active interval to transmit non-periodic traffic to be transmitted urgently, as well as a network connection. Also, when the M2M device supports a certain quality of service (QoS) application service, a time slot of a contention-free interval (contention-free interval) determined to be transferable for data and control commands can be used. In other words, since it is possible to selectively provide a contention free period and a contention free period (contention free period) for data transmission according to the QoS of the M2M device application service, it is efficient when the frequency of channel occupation is not high and the number of M2M devices is large .

An initial connection step in which the object communication device accesses the AP through a wireless link and is allocated a traffic channel, a traffic discrimination step of discriminating a type of data and control traffic to be transmitted and a transmission channel for the discriminated traffic, A traffic transmission step of transmitting the corresponding traffic through a transmission channel, and a connection releasing step of releasing the connection between the object communication device and the AP, which are no longer valid according to the reason for deactivation of the wireless link.

FIG. 8 is a diagram illustrating a process in which the object communication device performs medium access control in a macro-cell network according to an embodiment of the present invention.

The object communication device includes the above-mentioned M2M device.

The object communication device receives information of an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of a wireless network to which the object communication device is connected (S810). Herein, the receiving of the information of the AP includes receiving information included in the channel of the broadcasting interval of the first frame period of the wireless network provided by the AP. In more detail, the received information includes information of the AP, frame structure information for MAC (Medium Access Control) of the wireless network, random access information of the contention access period, and radio link control information of the wireless network And may include one or more. In more detail, in step S810, broadcast information may be received from a plurality of channels included in the broadcast section 315 of FIG. 3. The broadcast information includes a broadcast channel (BCH), a frame control channel (FCCH) Lt; / RTI > is broadcast in the cell periodically transmitted over the channel (LCCH). Accordingly, even when a new device is coupled to a wireless network, it can access the wireless network through the broadcast information periodically provided in the corresponding cell.

In step S820, the object communication device requests a connection using a random access in a contention access period of the first frame period of the wireless network, that is, in a contention access period, using the received information. The frame of FIG. 8 may be a MAC frame. The contention access period can be performed through the RACH, and the RACH period is a period in which all the devices can attempt to access, and the random access is performed. The random access is a connection in which the object communication device tries to occupy a channel using a random backoff in units of time slots, and can apply the CSMA / CA scheme. In applying the random backoff, a consistent backoff can be operated.

In applying the backoff condition, if the frame is not completed within the frame, the backoff operation may be performed as if the contending access intervals of all frames are connected, or a backoff operation may be performed by applying a new backoff value You may. This can be applied variously in consideration of the implementation method, the priority of the object communication device, and the like.

If the connection request is successful, the object communication device receives a response to the connection request from the AP and information on a contention free period that the object communication device can use exclusively in the wireless network (S830 ). The information on the contention-free period may include a time slot number of the uplink and the downlink in the contention-free period and an identifier of the object communication device. That is, the object communication device exclusively occupies the uplink and the downlink in an interval indicated by the time slot number according to a connection schedule in a contention-free interval of the frame period of the wireless network, and performs traffic transmission with the AP . The timeslot number may be set to be the same for the uplink and the downlink, or may be set differently. In another embodiment of the information that can be received when the connection request is successful, information regarding the schedule information or the period for transmitting the data, and information related to the wake-up period of the object communication device, may also be received. In addition, the information received in S830 may include information on a starting point of time when the object communication device starts periodic data transmission with the up / down time slot, for example, based on a frame unit . The object communication device can transmit traffic using the starting point and the above-mentioned schedule information, transmission period, and time slot.

In addition, in step S830, the information on the contention free period is received by the traffic channel, and information can be received in the first frame period in which the connection is requested. That is, as described above, the frame period is divided into two broadcasting periods, and information necessary for the allocation of the traffic channel and the response information for the connection request can be received through the AFCH, which is the connection response channel of the second broadcasting period. The response to the connection request can be implemented to be notified collectively for all the object communication devices requested to be connected through the AFCH.

In the contention-free period received in step S830, the object communication device can be used exclusively. In this case, a frame period in which the object communication device can transmit traffic may be limited according to a schedule, a data transmission period, etc. Therefore, when these schedules / periods are appropriately adjusted in units of frames, And can transmit and receive data with an exclusive interval.

Thereafter, the object communication device determines whether it is necessary to periodically transmit traffic (S840). As a result, when the aperiodic traffic transmission is required, the first traffic transmission is performed using the random access in the contention access period of the second frame period of the wireless network in operation S850. The second frame period is a temporally following frame period which is not overlapped with the first frame period which previously requested connection. Traffic transmission can be performed using a random access in the competing access interval of this interval, and this process has been described above with reference to FIG. 5 and FIG. In the random access of S850 and the random access of S820, the random access priority of S850 can be further increased. This is to allow aperiodic traffic transmission to occur more quickly.

On the other hand, in the case of periodic traffic transmission, traffic is transmitted in a time slot that can be dedicated using the information on the contention-free interval received previously. That is, the object communication device determines a connection schedule and an interval indicated by the time slot number in a contention-free interval of the wireless network, exclusively occupies the uplink and the downlink, and performs traffic transmission with the AP (S860).

FIG. 9 is a diagram illustrating a process in which the object communication device performs medium access control when the AP transmits aperiodic traffic in an embodiment of the present invention. The steps S910, S920, and S930, which are duplicated with the medium access control process illustrated in FIG. 8, will be described with reference to S810, S820, and S830 in FIG. After step S930, the object communication device is in the sleep mode if there is no data to be transmitted separately, and wakes up according to the wakeup schedule.

That is, the first broadcast channel of the first frame is received after wake up according to the wakeup schedule. After the wakeup, the AP receives the channel of the first broadcasting interval of the second frame interval (S940). If the paging message is included (S950), it indicates that traffic to be transmitted aperiodically is generated in the AP. Therefore, it receives the temporary traffic channel information in the second broadcast channel, for example, the AFCH, In step S960, traffic is received from the AP in the corresponding traffic channel using the downlink time slot indicated by the information. That is, the temporary traffic channel information includes the time slot number of the uplink and the downlink, the start time of the temporary traffic channel, and the period during which the corresponding temporary traffic channel is valid. On the other hand, if there is no separate paging message and there is no traffic to be transmitted by the object communication device, the sleep mode may be performed again (S970).

The structure of the frame, that is, the MAC frame illustrated in FIGS. 8 and 9, consists of a transport section on the downlink, a contention access section on the uplink, and a traffic transmission section on the uplink and downlink. A frame structure and an FCCH for broadcasting random access related information, an LCCH for broadcasting a radio link control related reference, and an AFCH for broadcasting a connection response and a channel allocation result. At this time, the BCH / FCCH / LCCH becomes one broadcasting section because the broadcasting section is divided into two, and the AFCH can be a separate broadcasting section. In addition, the contention access period on the uplink may be composed of a plurality of random access channels RACH.

The traffic transmission period constituting the non-contention period may be divided into an uplink and a downlink, and may have a plurality of time slots, but may be configured to have the same number of times.

Also, as illustrated in FIG. 3, the traffic transmission period may be arranged such that the uplink and the downlink are temporally distinguished by the AFCH. In addition, the frame structure can be implemented such that the uplink and downlink traffic sections start in conjunction with the downlink broadcast sections, respectively.

Also, each time slot of each link in a traffic transmission period that is a contention-free period may be occupied by a plurality of object communication devices at different points in time. This may be implemented by occupying other frames at different time points, even if they have the same time slot according to a data transmission period, a schedule, or the like.

In FIGS. 8 and 9, it is possible to use a contention free period or a contention access period by determining whether a specific traffic is non-periodic or periodic. In this case, it is possible to determine whether the traffic is to be transmitted in an irregular manner or in a periodic manner according to the urgency of the traffic to be transmitted, and when the time slot in the contention-free period in which traffic can be transmitted occupies.

The traffic transmission using the frame structure of FIGS. 8 and 9 can be implemented by a confirmation operation according to the traffic transmission by the transmission side and the reception response transmission by the reception side. On the other hand, in case of periodic traffic transmission, the transmitting side transmits through the allocated time slot, and the acknowledgment is transmitted from the receiving side through the time slot of the opposite direction link. The traffic transmission by the confirmation operation may be implemented such that the object communication device transmits the RACH through the contention access period and the response transmitted by the AP is the AFCH, which is the access response channel, for the non-periodicity.

10 is a diagram illustrating a process of controlling a wireless network in an AP so that the object communication device performs medium access control in a macro cell network according to an embodiment of the present invention. The description of the same parts applied in the process of explaining the medium access control of the object communication device shown in Figs. 8 and 9 will be omitted.

The AP (Access Point) transmits information on the wireless network and the AP that controls the wireless network through a broadcast channel of the wireless network (S1010). As described above, the information of the AP for controlling the wireless network and the wireless network includes the information of the AP, the medium access control (MAC) of the wireless network in the channel of the broadcasting interval of the first frame period of the wireless network Frame structure information for the contention access point, random access information for the contention access period, radio link control information of the radio network, and the like.

Then, the message transmitted by the object communication device in the contention access period (Contention Access Period) is received (S1020). Such a contention access interval may be a RACH interval for performing the random access as described above. The random access is a connection in which the object communication device tries to occupy a channel using a random backoff in units of time slots, and can apply the CSMA / CA scheme.

The received message may be a message requesting connection or a message related to transmission of traffic (S1030). In the case of a message requesting initial connection, a response to the connection request and information on a contention free period that the object communication device can use exclusively in the wireless network are transmitted (S 1040). The information on the contention-free period may be a time slot number of the uplink and downlink and an identifier of the object communication device in the contention-free period. same. The object communication device having received the information on the contention free period occupies the uplink and the downlink exclusively in the access schedule of the contention free period of the wireless network and in the interval indicated by the time slot number, And performs traffic transmission with the AP.

Meanwhile, if the received message is a message related to traffic transmission, a response to the aperiodic traffic transmitted by the object communication device included in the message is transmitted (S 1050). That is, when the object communication device transmits the aperiodic traffic in the RACH interval through the random access, the response including the processing result to the object communication device can be transmitted to the object communication.

The AP may process the random access by raising the priority of the object communication device in the random access related to the traffic transmission to the priority of the object communication device in the random access requesting the connection.

11 is a diagram illustrating a process of controlling a wireless network in an AP so that the object communication device performs media access control in a macro cell network according to another embodiment of the present invention. It can be applied when the AP desires to transmit the aperiodic traffic to the object communication device after performing the initial connection request in Fig. The AP determines whether it is necessary to transmit non-periodic traffic to the object communication device connected to the wireless network (S1110). If the non-periodic traffic transmission is required (S1120), the wakeup schedule of the object communication device is confirmed, and a paging message is included in the first broadcasting interval of the frame in which the object communication device is woken up (S1130). In addition, temporary traffic channel information to which the aperiodic traffic is to be transmitted is included in the second broadcasting period of the frame (S1140).

Periodic traffic to the object communication device using the downlink timeslot indicated by the temporary traffic channel information (S1150). The process of FIG. 11 is as described in FIGS. 6 and 7.

The AP in FIGS. 10 and 11 is a device for providing a control function for controlling the wireless network, and is not limited to the name of an access point. That is, Figs. 10 and 11 and the above-described embodiments can be applied to all devices that provide a function of controlling a wireless network.

Although not shown in Figures 8, 9, 10, and 11, it may include a disconnection step.

The disconnection step, as described above, means disconnecting the AP from the object communication device that is no longer valid according to the wireless link disconnection reason. The object communication device can repeatedly and continuously check the validity of its own traffic channel by using the above-described methods. If it is determined through this process that the wireless link is valid and traffic to be transmitted is generated, Step is performed. However, if it is determined that the wireless link is not valid, the object communication device or AP may retrieve and disconnect the traffic channel, i.e., the timeslot assigned to the particular M2M device, through a series of messages or processes.

FIG. 12 is a diagram illustrating a configuration of an object communication device and an AP for controlling a wireless network according to an embodiment of the present invention.

The object communication device 1210 and the access point (AP) 1220 transmit the traffic through the wireless network 1200. [

The object communication device 1210 includes a receiving unit 1216, a transmitting unit 1214, and a controlling unit 1212. The object communication device 1210 is an apparatus that implements the processes of FIGS. The description of the same parts applied in the process of explaining the medium access control of the object communication device shown in Figs. 8 and 9 will be omitted.

The receiving unit 1216 receives the signal transmitted from the wireless network, and the transmitting unit 1214 transmits the signal to the wireless network. The control unit 1212 controls the receiving unit 1216 and the transmitting unit 1214. The control unit 1212 controls the receiving unit 1216 to receive information of an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of a wireless network to which the object communication device is to access And controls the transmitter 1214 to request a connection using a random access in a contention access period of a first frame period of the wireless network using the received information.

When the receiving unit 1216 receives a response to the connection request from the AP and information on a contention free period that can be used exclusively by the object communication device in the wireless network, (1216) for performing the first traffic transmission using the random access in the contention access period of the second frame period of the wireless network when the AP is required to transmit the aperiodic first traffic, And controls the transmission unit 1214.

In addition, when the AP desires to transmit aperiodic information, the controller 1212 receives the paging message included in the channel of the first broadcasting interval of the third frame interval provided by the AP after the wakeup Periodic traffic transmission from the AP and controls the reception unit 1216 to receive the temporary traffic channel information included in the channel of the second broadcasting period of the third frame period. Thereafter, the controller 1212 controls the transmitter 1214 to receive non-periodic traffic from the AP using the downlink timeslot indicated by the temporary traffic channel information.

The AP 1220 is a device that implements the processes of FIGS. 10 and 11 as described above. The AP 1220 includes a receiving unit 1226, a transmitting unit 1224, and a controlling unit 1222. 8, 9, 10, and 11 will not be described in detail.

The receiving unit 1226 receives the signal transmitted from the wireless network, and the transmitting unit 1224 transmits the signal to the wireless network.

And a control unit 1222 for controlling the receiving unit 1226 and the transmitting unit 1224,

The control unit 1222 transmits information on an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of the wireless network, and the receiving unit 1226 transmits information on an access point And controls to receive a message using a random access in a contention access period of one frame period.

When the received message requests a connection, the controller 1222 transmits a response to the connection request and information about a contention free period (exclusive use period) that the object communication device can use exclusively in the wireless network The control unit 1224 controls the transmission unit 1224 to transmit the data.

If the control unit 1222 determines that the received message is a message related to traffic transmission, the control unit 1222 controls the transmission unit 1224 to transmit a response to the aperiodic traffic transmitted by the object communication device included in the message .

On the other hand, when the AP 1220 desires to transmit the non-periodic traffic, the controller 1222 determines that the non-periodic traffic transmission is required to the object communication device and confirms the wakeup schedule of the object communication device.

The control unit 1222 controls the transmission unit 1224 to transmit the paging message after the paging message is included in the first broadcasting interval of the second frame in which the object communication device is woken up, Periodic traffic channel information to be transmitted in the second broadcasting period of the frame and controls the transmission unit 1224 to transmit the temporary traffic channel information.

Thereafter, the controller 1222 controls the transmitter 1224 to transmit non-periodic traffic to the object communication device using the downlink timeslot indicated by the temporary traffic channel information.

13 is a diagram illustrating a medium access process according to an embodiment of the present invention. Any M2M device wishing to join the network goes through an initial connection (S1310). As described above, the M2M device searches for a BCH and listens for BCH, FCH, and LCCH in order to establish a wireless link to operate as a network member. In this process, the M2M device sequentially receives BCH, FCH, and LCCH messages, The MAC frame information, the random access related information, and the link control related information.

Thereafter, the M2M device is allocated a traffic channel (S1320). In order to allocate the traffic channel, the M2M device makes a connection request through a random access using the RACH of the contention free period, and if the request is valid, the AP allocates a dedicated traffic channel and allocates a node ID through a time division slot sharing method . The result is transmitted through the AFCH starting the downlink interval in the same MAC frame interval, thereby notifying the M2M device that the connection request is normally accepted. The M2M device also verifies that the network connection was successful by receiving it.

After a dedicated time slot has been allocated as a traffic channel, the M2M device remains active in its time slot according to the transmission schedule by the data transmission period and in the downlink broadcast interval according to the wakeup schedule for listening to broadcast and paging information It supports periodic traffic and non-periodic traffic.

It is checked whether the traffic to be transmitted is periodic (S1330), and if it is periodic, the traffic is transmitted within the allocated interval (S1360). On the other hand, if it is not periodic, it is confirmed whether the traffic is uplink traffic (S1340). In case of uplink traffic, the M2M device listens for the broadcast channel of the downlink broadcasting period, transmits the traffic to the AP through the random access using the RACH, receives the acknowledgment through the AFCH of the same MAC frame interval, Complete.

If the AP does not have uplink traffic, that is, if the AP has data requiring urgent transmission such as a control command at a time other than the transmission schedule, the AP designates a temporary traffic channel (S1350). In other words, Checks the wakeup schedule and notifies the corresponding M2M device of the traffic information being pending through the downlink broadcast channel of the MAC frame corresponding to the earliest wakeup time as paging. The AP selects a temporary traffic channel available for the transmission of the waiting traffic and transmits it to the corresponding M2M device through the AFCH. It is reasonable that the ad hoc traffic channel is operated for a time period in which the transmission of the urgent data can be completed and can be selected to be valid for at least two MAC frame intervals. Meanwhile, the corresponding M2M device awakes from the sleep mode according to the wakeup schedule and receives the broadcast channel. When receiving the paging for notifying that the received traffic is in the transmission waiting state in the AP as described above, the M2M device receives the channel of the remaining broadcasting interval and transmits the MAC frame structure and the radio link information And then receives the temporary traffic channel information for itself by listening to the AFCH. The temporary traffic channel information includes an uplink time slot number, a start time of the ad hoc traffic channel, and an expiration time (in units of a MAC frame period). The starting point of the ad hoc traffic channel is the difference between the current MAC frame interval and the current MAC frame interval and has a value of 0 when it is the current MAC frame interval. If the ad hoc traffic channel is not the downlink time slot of the current MAC frame, the M2M device transitions to the sleep mode, and then the AP awakes again in the selected MAC frame interval and receives traffic notified by the AP. Then, it is checked whether the current wireless link is valid (S1370), and if it is not valid, the traffic channel is released (S1380).

As described above, according to the present invention, the MAC frame structure enables medium access control for allowing many M2M devices operating at a low duty cycle to share one traffic channel and quickly transmit bidirectional emergency data at a time other than a data transmission period .

Therefore, according to the medium access method according to the present invention, since the dedicated time slots are shared in a time division manner and the transmission time of the non-periodic data is determined based on the wakeup schedule, it is possible to simultaneously support a plurality of M2M devices operating at low duty cycles, Speed bidirectional transmission of traffic is possible.

The foregoing description is merely illustrative of the technical idea of the present invention and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (22)

Comprising: receiving information of an access point for controlling a wireless network and the wireless network through a broadcast channel of a wireless network to which the object communication device is to access;
Requesting a connection using a random access in a contention access period of a first frame period of the wireless network using the received information;
Receiving a response to the connection request from the access point and information on a contention free period that the object communication device can use exclusively in the wireless network; And
And performing the first traffic transmission using a random access in a contention access period of a second frame period of the wireless network when aperiodic first traffic transmission is required to the AP,
Wherein the first frame period and the second frame period include the contention access period and the contention free period,
The object communication device performing a wake-up;
Receiving a paging message included in a channel of a first broadcast interval of a third frame interval provided by the AP after the wakeup and temporary traffic channel information included in a channel of a second broadcast interval of the third frame interval; And
Further comprising receiving non-periodic traffic from the AP using a downlink timeslot indicated by the temporary traffic channel information.
The method according to claim 1,
The step of receiving the information of the wireless network and the AP controlling the wireless network
Receiving information included in a channel of a broadcast interval of the first frame period of the wireless network provided by the AP,
The received information includes at least one of the AP information, frame structure information for MAC (Medium Access Control) of the wireless network, random access information for the contention access period, and wireless link control information of the wireless network Wherein the macrocell M2M accesses the network.
The method according to claim 1,
The information on the contention free period is
A time slot number of uplink and downlink in the contention free period and an identifier of the object communication device.

The method according to claim 1,
Characterized in that the priority of the object communication device in the random access in the step of performing the first traffic transmission over the priority of the object communication device in the random access in the step of requesting the connection is high. M2M network medium access control method.
delete Transmitting information of an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of the wireless network;
Receiving from the object communication device a message relating to a message requesting connection or a traffic transmission using a random access in a contention access period of a first frame period of the wireless network; And
A response to the connection request and information on a contention free period that the object communication device can use exclusively in the wireless network when the received message requests a connection,
Transmitting a response to the aperiodic traffic transmitted by the object communication device included in the message when the received message is a message related to traffic transmission,
Wherein the first frame period and the second frame period include the contention access period and the contention free period,
Periodic traffic transmission is required to the object communication device, the wake-up schedule of the object communication device is confirmed, and the paging message is included in the first broadcasting interval of the second frame in which the object communication device is woken up Transmitting;
Transmitting temporary traffic channel information to be transmitted with the aperiodic traffic in a second broadcasting period of the second frame; And
Further comprising transmitting non-periodic traffic to the object communication device using downlink timeslots indicated by the temporary traffic channel information.
The method according to claim 6,
The information of the wireless network and the AP controlling the wireless network
Wherein the information on the AP, the frame structure information for MAC (Medium Access Control) of the wireless network, the random access information on the contention access period, And the radio link control information, and the radio link control information.
The method according to claim 6,
The information on the contention free period is
A time slot number of uplink and downlink in the contention free period and an identifier of the object communication device.

The method according to claim 6,
In the receiving step,
Characterized in that the priority of the object communication device in the random access requesting connection is higher than the priority of the object communication device in the random access. Access control method.
delete A receiver for receiving signals transmitted in a wireless network;
A transmitter for transmitting a signal to the wireless network; And
And a control unit for controlling the receiving unit and the transmitting unit,
Wherein the control unit controls the receiving unit to receive information of an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of a wireless network to which the object communication device is to access, Controls the transmission unit to request a connection using a random access in a contention access period of a first frame period of the wireless network,
Wherein the control unit controls the receiving unit to receive a response to the connection request from the AP and information on a contention free period that the object communication device can use exclusively in the wireless network,
Wherein the control unit controls the receiving unit and the transmitting unit to perform the first traffic transmission using the random access in the contention access period of the second frame period of the wireless network when the AP requires aperiodic first traffic transmission .
When the receiver receives the paging message included in the channel of the first broadcasting interval of the third frame interval provided by the AP after the wakeup, Wherein the control unit controls the receiving unit to receive the temporary traffic channel information,
Wherein the control unit controls the transmission unit to receive aperiodic traffic from the AP using the downlink timeslot indicated by the temporary traffic channel information. device.
delete A receiving unit for receiving a signal transmitted from the object communication device;
A transmitter for transmitting a signal to the object communication device; And
And a control unit for controlling the receiving unit and the transmitting unit,
Wherein the controller transmits information of an access point (AP) that controls the wireless network and the wireless network through a broadcast channel of the wireless network, and the receiver transmits information of a contention period of the first frame period Access Period) to receive a message using a random access,
When the received message requests a connection, the control unit transmits a response to the connection request and information on a contention free period that the object communication device can use exclusively in the wireless network Controls the transmitting unit,
Wherein the control unit controls the transmission unit to transmit a response to the aperiodic traffic transmitted by the object communication device included in the message when the received message is a message related to traffic transmission,
Wherein the control unit determines that the non-periodic traffic transmission is required to the object communication device and confirms the wakeup schedule of the object communication device so that the transmission unit notifies the object communication device of the first broadcast of the second frame in which wake- Periodic traffic is included in the second broadcasting interval of the second frame and includes temporary traffic channel information to be transmitted,
Wherein the control unit controls the transmission unit to transmit non-periodic traffic to the object communication device using a downlink time slot indicated by the temporary traffic channel information, Access point used.
delete delete delete delete delete delete delete delete delete

Images