KR101822616B1 - Communication method for source device, destination device and relay device - Google Patents

Abstract

A communication method of a source apparatus according to an embodiment of the present invention detects a state of a first link directly connected to a destination apparatus from a source apparatus or a second link connected to the destination apparatus via the relay apparatus from the source apparatus ; Selecting one of the first link and the second link based on the detection result; And transmitting data using the selected link.

Description

Technical Field [0001] The present invention relates to a source device, a destination device, and a communication method for a relay device,

The following embodiments relate to a communication method of a source apparatus, a destination apparatus and a relay apparatus in a wireless system.

Millimeter waves, such as the 60 GHz band where the standardization is currently performed, can easily transmit data of several gigabits (Gbps) without high modulation by using a broadband of about 2 GHz, but have a strong directivity due to high frequency characteristics Power loss is large. In order to compensate for this, a method of obtaining a high antenna gain by collecting power in a specific direction rather than a forward direction using a directional antenna is used.

However, if the line-of-sight (LOS) is not secured, the signal must be reflected and transmitted. In such a case, the loss due to reflection is added because the distance is increased and the attenuation loss is increased. In addition, penetration loss is 20dB or more when the person is blocked by the visual field, and the door or wall existing in the room usually has a larger loss and the signal can not be reached. In addition, the communication in the 60 GHz band limits the reaching distance to within 10 m, and even if there is no reflection or penetration loss, there is a possibility that the signal can not reach due to the attenuation depending on the distance.

WLANs that are more than 10 meters in width, such as a typical home, and used in the band below 5 GHz have a distance of several tens of meters, so a single network can cover all of these distances. In contrast, the communication in the 60 GHz band is not performed, so that the users can feel inconvenience. Furthermore, as described above, in the case of a room or a room where a visible distance is blocked by a door or a wall, or between a room and a living room, it is necessary to compensate it because it is difficult to constitute a single network.

Therefore, communication methods (for example, a wireless local area network (WLAN) or a wireless personal area network (WPAN)) considering a directional communication suitable for such a band are being considered. However, if the network situation changes dynamically, such as when a person has blocked the LOS during data transmission, a visible link (LOS) communication is not possible and a bypass link should be used. In this case, You have to be motivated.

Also, in order for the transmitter to receive the signal sent to the bypass link without missing, the receiver must adjust the reception direction of the signal before the transmitter, and a relay method that can be used in the reserved interval regardless of the transmission method used in the bypass link need.

In an embodiment of the present invention, when MAC access is performed using a directional antenna, a link switching method and a data transmission method after a link switching, A source device, a destination device, and a relay device capable of using a reserved section in a unified manner regardless of the source device, the destination device, and the relay device.

A communication method of a source apparatus according to an embodiment of the present invention detects a state of a first link directly connected to a destination apparatus from a source apparatus or a second link connected to the destination apparatus via the relay apparatus from the source apparatus ; Selecting one of the first link and the second link based on the detection result; And transmitting data using the selected link.

A communication method of a destination apparatus according to an embodiment of the present invention includes a first link directly connected to a destination apparatus from a source apparatus or a second link connected from a source apparatus to the destination apparatus via a relay apparatus, Determining whether a link selected by the device is available; And receiving data based on the determination result.

A communication method of a relay apparatus according to an embodiment of the present invention is characterized in that a source apparatus has a first link directly connected to the destination apparatus from the source apparatus and a second link connected from the source apparatus to the destination apparatus via the relay apparatus, Waiting for data reception from the source apparatus at a start point of a predetermined link change interval when the second link is selected as the selected link; And transmitting the data to the destination device.

According to an embodiment of the present invention, when the visible range (LOS) link is blocked due to an obstacle, the bypass link via the relay device is switched to facilitate data transmission, and the relay device can perform full duplex, Or Half Duplex (Half Duplex) method.

1 is a flowchart showing a communication method of a source apparatus according to an embodiment of the present invention.
2 is a flowchart showing a communication method of a destination apparatus according to an embodiment of the present invention.
3 is a flowchart illustrating a communication method of a relay apparatus according to an embodiment of the present invention.
4 is a diagram for explaining frame transmission rules added when data is transmitted using an AF relay apparatus using a full duplex (FD) relay scheme according to an embodiment of the present invention.
5 is a diagram illustrating a frame structure of an 802.11 WLAN used in an embodiment of the present invention.
FIG. 6 is a diagram illustrating frame transmission rules added when data is transmitted using a DF (Decode and Forward) relay apparatus using a half duplex (HD) relay scheme according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. In addition, the same reference numerals shown in the drawings denote the same members.

Hereinafter, a source device, a destination device, and a relay device each have a directional antenna and a communication terminal capable of acting as a source, a destination and a relay in a communication network, a base station, Device. It is assumed that each of the source device, the destination device, and the relay device uses reservation-based medium access control. Further, the data described below is a concept including a data frame, a data packet, and the like.

WLANs and WPANs provide a way to transmit data in a non-contention-based manner. AP (Access Point) of WLAN or PNC (Pico Net Coordinator) of WPAN divides a time zone into a competition zone and a non-competition zone.

In the contention period, all devices in the network compete based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) to acquire channels.

Also, in a contention-free period, the AP or the PNC may use a specific time domain of the contention-free period for data transmission by a polling technique or a method of transmitting scheduling information.

According to an embodiment of the present invention, there is provided a method of switching a link for transmitting data when a link in data transmission in a contention-free period is interrupted, that is, switching a link, and a relay method A method for properly relaying and transmitting data will be described.

A method for switching a link described below and a method for relaying and transmitting data according to a relay method are based on IEEE 802.11 WLAN.

Initially, an initialization process such as link setting and beamforming is performed between the relay device, the source device, and the destination device, and it is assumed that the three devices are preparing to transmit or prepare data in the interval reserved by the coordinator.

The relay use mode can be defined in the initialization process. The first field of the relay use mode indicates a normal / alternation mode, and the second field indicates a full duplex (FD) relay mode. (DF) relay device of an Amplify-and-Forward (AF) relay device and a Half Duplex (HD) relay scheme.

The decode and forward (DF) relay apparatus of the half duplex (HD) relay system does not operate in the exchange mode but operates only in the normal mode.

The normal mode is a method in which the source device and the destination device continuously exchange frames only on either a direct link or a relay link unless blockage occurs in the link or channel degradation becomes severe and unusable .

In the alternation mode, a link change interval is a method of exchanging frames by alternating two links at predetermined intervals.

The source device determines whether to transmit data in the normal mode or the exchange mode, and the data is sent to the relay device and the destination device. The value is not changed unless the source device changes the mode.

1 is a flowchart showing a communication method of a source apparatus according to an embodiment of the present invention.

FIG. 1 shows a method of switching a link in which a source device transmits data when a link in data transmission in a contention-free period is blocked.

The source device may store parameters including a data sensing time for detecting whether the destination linkage interval or the destination device has transmitted data over the link selected by the destination link and the relay device You can tell.

In addition, the source apparatus can transmit information about an operation mode used for transmitting data to the destination apparatus and the relay apparatus, and information on a relay scheme of the relay apparatus (101).

At this time, the selected link may be either a first link directly connected to the destination apparatus from the source apparatus or a second link connected from the source apparatus to the destination apparatus via the relay apparatus. The relay system of the relay apparatus may include at least one of a full duplex (FD) scheme and a half duplex (HD) scheme.

In the case of the full duplex (FD) scheme, the relay device switches the first link to the second link in the Link Change Interval preset by the source device, and after the data sensing time, Data can be transmitted through a link.

The data sensing time is a time required for the destination apparatus to detect whether data has been transmitted through the selected link (here, the first link).

In the case of the half-duplex (HD) scheme, the relay apparatus replaces the predetermined link change interval used in the full-duplex scheme by using a first period for the relay link between the source apparatus and the relay apparatus, Data may be transmitted according to a second period for a relay link between the NN devices.

The first period and the second period may be set or updated by the source apparatus in the same manner as the data sensing time.

When the half duplex scheme is used, the source apparatus transmits the data to the destination apparatus on the basis of at least one of the result of the beamforming obtained before transmitting the data to the destination apparatus and the quality information of the link obtained during transmission of the data on the link, Or may set or update the second period.

The first period for the relay link between the source apparatus and the relay apparatus may be started when the source apparatus switches the first link to the second link.

In addition, a predetermined link change interval (Link Change Interval) can be restarted when the source device switches the link from the second link to the first link.

The mode of operation in which the source device is used to transfer data to the destination device and the relay device may include at least one of a normal mode and an exchange mode.

The normal mode is a mode in which data is transmitted to the destination device using any one link until it is determined that either the first link or the second link is unavailable.

The alternation mode is a mode in which the source device uses the first link and the second link alternately and transmits data to the destination device at the start point of the predetermined link change interval .

At this time, the second link may be formed between the source apparatus and the relay apparatus (S-R) and between the relay apparatus and the destination apparatus (R-D).

The source apparatus detects (103) the status of the first link directly connected to the destination apparatus from the source apparatus or the second link connected via the relay apparatus to the destination apparatus from the source apparatus.

The source apparatus selects one of the first link and the second link based on the detection result (105).

At 105, the source device may switch either the first link or the second link to the selected link in a preset Link Change Interval based on the detection result.

Here, the source apparatus adjusts the directional antenna direction of the source apparatus according to the result of the beam forming obtained in advance through the unselected link, thereby increasing the transmit antenna gain of the data through the unselected link.

At 105, the source apparatus selects either of the first link and the second link based on the link quality information obtained from the ACK signal for the previous data transmitted to the destination apparatus via the selected link or the frame for estimating the state of the channel One link can be selected.

At this time, whether the link is blocked or whether the quality of the link corresponds to the quality of a predetermined link can be used to select any one of the first link and the second link.

In selecting a link of either the first link or the second link, if the source device determines that the first link or the second link is unavailable, The link selected in the next link change interval of the interval can be switched to the unselected link. Here, the term " unavailable link " is not limited to a blocked link, and even if an unblocked link has a state of lower quality than that of an available link, '.

The source device transmits data using the selected link (107).

At 107, the source device determines whether the destination device has a data sensing time for sensing whether data has been transmitted over the selected link, or a switching time for the destination device to switch to a non- switching time may be considered.

If the source device has decided to resume the transmission of data in accordance with the above-described exchange mode, the source device informs the destination device that the operation on the selected link has been resumed, the data of the next link change interval of the link change interval After the sensing time, data can be transmitted to the destination device.

The source device may perform switching to a link that is not periodically selected to monitor the quality of the unselected link of either the first link or the second link.

When the source device switches from the first link to the second link to monitor the quality of the unselected link, the source device may send a request frame to the relay device to monitor the quality of the first link. The source apparatus may receive a response frame containing information indicating the quality of the first link in response to the request frame from the relay apparatus.

In addition, when the source apparatus switches from the second link to the first link to monitor the quality of the unselected link, the source apparatus sends a request frame for monitoring the quality of the link between the source apparatus and the relay apparatus of the second link, Lt; / RTI >

Thereafter, the source apparatus, in response to the request frame, transmits information regarding the quality of the link between the source apparatus and the relay apparatus in the second link and the quality of the link between the relay apparatus and the destination apparatus received from the destination apparatus Lt; RTI ID = 0.0 > a < / RTI >

A request frame for monitoring the quality of the second link and a response frame corresponding to the request frame to the destination apparatus.

Hereinafter, the operation of the source apparatus will be described on the assumption that the source apparatus is transmitting data using the first link according to an embodiment. The source device may determine whether the first link being used to transmit data to the destination device is blocked.

At this time, the source apparatus can judge whether or not the first link currently in use is blocked according to a preset rule used for transmitting data to the destination apparatus.

Here, the preset rule may be a rule that the source device receives a time instance required for transmitting data to the destination device or an ACK transmitted from the destination device to the source device, And whether or not they have done so.

If it is determined that the first link is blocked, the source apparatus can switch the first link currently in use to the second link according to a predetermined link change interval (Link Change Interval). If it is determined that the first link is blocked, the source apparatus may switch the first link to the second link in the next link change interval of the preset link change interval (here, the link change interval to which the blocked moment belongs).

Then, the source apparatus transmits the data using the second link.

At this time, the source device may transmit data using the second link after a time considering a data sensing time and a switching time.

The switching time is the time it takes for the destination device to switch the link from the first link to the second link.

If it is determined that the first link is not blocked, the source apparatus can continue to use the first link without switching the link to transmit data to the destination apparatus.

Also, the source apparatus may transmit a request frame to the relay apparatus connected to the second link to determine whether the data received by the relay apparatus has been successfully transmitted to the destination apparatus.

Here, the request frame may be a Relay ACK Request frame as shown in Table 1 below.

When the relay system of the relay apparatus is of the half duplex system, the source apparatus transmits data according to the first period and the second period instead of the link change interval.

Since the ACK in the second period is transmitted to the destination apparatus by the relay apparatus, the relay apparatus can know the status of the link RD, but the source apparatus can not know the status of the link RD. The status can not be known.

Therefore, the source apparatus can request the relay apparatus in the next first period to send information on whether the frame is transmitted well on the R-D link by sending a relay ACK request frame as shown in [Table 1] below.

Relay ACK Request Order Information One Category 2 Action 3 BAR Control 4 BlockAck starting Sequence Control

A relay ACK request frame is a frame that a source apparatus sends to a relay apparatus participating in a relay operation to know whether or not all frames transmitted to the relay apparatus have been successfully transmitted to the destination apparatus.

In response to the request frame, the source apparatus may also receive a response frame indicating whether data from the relay apparatus has been delivered to the destination apparatus.

Here, the response frame may be a Relay ACK Response frame.

The relay device responds to the relay acknowledgment frame with the relay acknowledgment frame shown in [Table 2] below.

Relay ACK Response Order Information One Category 2 Action 3 BA Control 4 BlockAck starting Sequence Control 5 BlockAck Bitmap

A relay arc frame is a frame that a relay device sends to a source device participating in a relay operation to report which frame was successfully transmitted to the destination device.

The operation of the source device according to the relay mode of each operation mode and the relay device, the data exchange rule in each mode, and the frame transmission rule will be described later.

2 is a flowchart showing a communication method of a destination apparatus according to an embodiment of the present invention.

FIG. 2 shows an operation of a destination apparatus when switching a link through which a source apparatus transmits data when a link in data transmission in a contention-free period is blocked.

The destination apparatus can receive information on the operation mode used by the source apparatus to transmit data from the source apparatus and the relay scheme of the relay apparatus in the initialization process. In addition, the destination device may receive a preset link change interval from the source device (201).

Here, the relay system of the relay apparatus may include at least one of a full duplex (FD) system and a half duplex (HD) system.

The first period and the second period used in the relay scheme and the half duplex (HD) scheme of the relay apparatus are no longer available when the first link is the selected link.

The link change interval may start at the beginning of the first period when the source device switches the link from the second link to the first link. For details of other full-duplex (FD) and half-duplex (HD) schemes and the first and second periods, refer to the description of corresponding portions of FIG.

Further, a description of the operation mode including at least one of the normal mode and the exchange mode is also referred to the description of the corresponding portion of Fig.

The destination device determines whether a link selected by the source device from among the first link directly connected to the destination device from the source device or the second link connected from the source device to the destination device via the relay device is available 203 ).

To determine whether the selected link is available, the destination device may determine whether or not the selected link is available depending on whether it has received data over the selected link for a certain period of time.

Here, the predetermined time may be a time from the start of a link change interval (LCP) interval to a time when a data sensing time elapses.

The destination device may switch the link of the destination device from the second link to the first link at the start of each first period to confirm whether the source device is switching from the second link to the first link.

In switching from the second link to the first link, the destination apparatus, when receiving the available data from the source apparatus via the first link, changes the link change interval from the start of the first period of receiving data on the first link, Can be regarded as being started.

Then, if the destination apparatus does not receive the available data from the source apparatus via the first link, the link of the destination apparatus at the start of the next second period of the next first period and the next second period, It is possible to switch to the second link.

At this time, in the next first cycle, the source apparatus transmits data to the relay apparatus, and in the next second cycle, the relay apparatus can transmit data to the destination apparatus.

The destination apparatus receives the data based on the determination result (205).

At 205, the destination device verifies whether the source device has switched to the selected link. Thereafter, if it is determined that the source device has switched to the selected link, the destination device may direct the directional antenna of the destination device toward the selected link and wait for reception of the data.

The destination apparatus is configured to switch the selected link to the unselected link when the operation mode is the normal mode and the destination apparatus does not receive the available data from the source apparatus within the data sensing time from the start point of the predetermined link change interval .

The operation of the destination apparatus when the operation mode is the exchange mode and data is received via the selected link is as follows.

When the operation mode is the exchange mode, the destination apparatus can receive data via the link selected at the start of the predetermined link change interval of the destination apparatus.

The destination apparatus can switch to a link that is not selected in the next link change interval of the preset link change interval. Thereafter, the destination apparatus can receive data from the beginning of the next link change interval.

When the value of the More Data field in the destination apparatus is '0', the operation of the destination apparatus according to the relay system and operation mode of the relay apparatus is as follows.

If the selected link is the second link and the value of the More Data field of the previous data frame is ' 0 ', the destination apparatus transmits a link via the relay apparatus May not switch the link to the first link even if it does not receive data during the second period.

When the operation mode is the normal mode and the value of the More Data field of the MAC header of the last frame received from the source apparatus is '0', the destination apparatus does not receive data during the data sensing time in the selected link The selected link can be maintained.

When the operation mode is the exchange mode and the value of the More Data field of the MAC header of the last frame received from the source apparatus is '0', the destination apparatus exchanges the link in the next link change interval of the preset link change interval , The selected link can be maintained as it is.

Hereinafter, the operation of the destination apparatus will be described on the assumption that the destination apparatus is receiving data using the first link according to an embodiment.

The destination device may determine whether the first link used to receive data from the source device is blocked. At this time, the destination apparatus can confirm whether or not the source apparatus has switched the first link.

Here, if the destination apparatus is confirmed that the source apparatus has switched the first link, the destination apparatus can direct the directional antenna of the destination apparatus toward the second link to wait for reception of the data.

The destination device switches the first link to the second link after the data sensing time has elapsed according to the link change interval preset by the source device when the first link is determined to be blocked, Lt; / RTI >

If it is determined that the first link is not blocked, the destination device can continue to receive data from the source device using the first link.

The destination device can switch the link from the direct link to the relay link if it fails to receive data at the proper time in the normal mode. That is, when the operation mode is the normal mode and the destination device does not receive the available data from the source device within the data sensing time from the start point of the predetermined link change interval, the destination device switches the direct link to the relay link .

In addition, if the destination device fails to receive data in the order expected in the exchange mode in the exchange mode, the destination device may remain in the current link instead of alternating the link.

That is, when the operation mode is the exchange mode and the destination apparatus receives the data of the second link in the next link change interval of the link change interval preset on the first link, instead of switching to the second link according to the exchange mode It is possible to keep the current first link at the present time.

The concrete operation of the destination apparatus according to each operation mode and the relay system of the relay apparatus, the data exchange rule in each mode, and the frame transmission rule will be described later.

3 is a flowchart illustrating a communication method of a relay apparatus according to an embodiment of the present invention.

FIG. 3 shows the operation of the relay apparatus as the source apparatus switches the link through which data is transmitted when the link in data transmission in the contention-free period is blocked.

When the source device selects the first link and the second one of the second links as the selected link, the relay device waits (301) for receiving data from the source device at the start point of the preset link change interval.

Here, the first link is a link directly connected from the source apparatus to the destination apparatus, and the second link is a link connected from the source apparatus to the destination apparatus via the relay apparatus.

The relay device can wait for data reception from the source device in the second link by adjusting the direction of the directional antenna of the relay device for a certain period of time from the start time of the preset link change interval.

The relay device receives (303) the data from the source device, and then transmits the data to the destination device (305).

The relay apparatus can receive information on the first period and the second period from the source apparatus. The relay device can then receive data from the source device in the first period and data to the destination device in the second period.

The first period is for the relay link between the source apparatus and the relay apparatus, and the second period is for the relay link between the relay apparatus and the destination apparatus.

The relay apparatus can receive from the source apparatus a request frame for grasping whether or not the data transmitted from the source apparatus to the relay apparatus has been delivered to the destination apparatus.

The relay device may then send a response frame in response to the request frame indicating whether the data has been delivered to the destination device.

The relay apparatus can operate according to at least one of a full duplex system and a half duplex system.

The Full Duplex scheme switches the first link to the second link in a predetermined link change interval and transmits the data to the destination through the data link for detecting whether data is transmitted through the first link And the data is transmitted to the second link after a data sensing time.

The half duplex scheme transmits data in the same manner as the full duplex scheme when the transmitting apparatus uses the first link and transmits data in accordance with the first period and the second period when the transmitting apparatus uses the second link. .

When the relaying method is the full duplex method, the relay device adjusts the direction of another directional antenna of the relay device for a certain period of time from the start time of the predetermined link change interval, and receives the data through the link toward the destination device .

If the relay scheme is a full duplex scheme, the relay apparatus transmits the operation of the directional antenna of the relay apparatus to the transmission / reception state according to the policy of the frame type and the ACK signal for each frame received by the relay apparatus You can switch. Hereinafter, the operation of the relay apparatus will be described on the assumption that the relay apparatus transmits and receives data using the second link.

The relay apparatus receives information on the first period and the second period from the source apparatus.

The relay apparatus receives data from the source apparatus in the first period, and transmits the data to the destination apparatus in the second period.

The relay apparatus can receive from the source apparatus a request frame for grasping whether or not the data transmitted by the source apparatus to the relay apparatus has been transmitted to the destination apparatus as described above.

In response to the request frame, the relay device may send a response frame indicating whether the data has been delivered to the destination device.

Here, the request frame may be a relay ACK request frame, and the response frame may be a relay ACK time frame. The description of [Table 1] and [Table 2] in Fig. 1 will be referred to for each frame.

Hereinafter, an operation for link switching between a source apparatus, a destination apparatus, and a relay apparatus, a data exchange rule and a frame transmission rule to be followed by a source apparatus, a relay apparatus, and a destination apparatus in an allocated resource will be described.

First, when a link in which data is being transmitted is blocked and a link is to be switched, the time instant at which the link is determined to be clogged may be different depending on the source apparatus and the destination apparatus. The fact that the time instances are different for each device (source device and destination device) means that the time of the beamforming process in which each device directs the transmitting and receiving ends to the new link for link switching may vary.

The time instance is different for each device, and as a result, the destination device may not receive data sent from the switched link by the destination device. Therefore, in one embodiment of the present invention, two parameters, that is, a link change interval and a data sensing time, are used to prevent this.

The first problem is solved by transferring data at an arbitrary moment by allowing switching of a link that transmits data only at a corresponding point in a predetermined period within a reserved interval.

Here, the predetermined period may be a link change interval, and the source device may share the information on the predetermined period by informing the relay device and the destination device of the value of the link change interval before transmitting the data.

Upon detecting that the currently active link is blocked during data transmission in accordance with a preset rule (e.g., no ACK is received), the source device may switch the link in the next link change interval to transmit the data have.

However, the destination apparatus may not know the link switching made by the source apparatus. This is because the destination apparatus correctly receives the data but the ACK sent in response thereto is lost while being transmitted to the source apparatus, so that the source apparatus may not recognize the ACK for the data transmission.

For this purpose, the source apparatus can transmit data after a predetermined time (for example, a data sensing time) without transmitting data immediately in the next link change interval.

The destination device is still waiting on the link before it is switched since it does not know whether or not link switching has occurred in the next link change interval. However, if the data is still not transmitted after a predetermined time, the destination device switches the link.

Here, in order to synchronize the synchronization between the two devices (the source device and the destination device), the destination device switches the link after a predetermined time defined as the data sensing time, and the source device changes the data sensing time and the switching time After the considered time, the data is transmitted using the switched link. This is because the source device is safe to transmit after the data transmission time, considering the switching time required by the destination device after the data sensing time.

However, the switching time can be ignored if it is less than the propagation delay transmitted from the source device to the destination device. have. Thus, the destination device switches the link after the data sensing time, and the source device can also be considered to send data on the switched link after the data sensing time. Therefore, since the destination apparatus is prepared first on the switched link, it is possible to properly receive the data transmitted from the source apparatus.

If the relaying method of the relay device is a full duplex (FD) method in the above-mentioned process, the source device and the destination device do not change in their operation.

However, if the relay device is a DF relay using a half duplex (HD) relay method, when the relay device transmits data to the relay link, the corresponding data must be decoded and then encoded again to be transmitted to the destination device. It needs a slot of the ship.

Also, since the quality of the two links (S-R link and R-D link) connected to the relay apparatus are different from each other, the time required to transmit the same data may be different. Therefore, in the case of the half-duplex relay scheme, a field indicating the length of two intervals is required. Each of these fields may be referred to as a first period and a second period.

The values of the two fields can be set or updated through the result of beamforming obtained before the data transmission by the source device or the quality information of the link acquired by requesting the data in the middle of the transmission interval. The source device then defines an information element (IE) that is a collection of related parameter sets. The source apparatus sends the IE-related parameter to the destination apparatus via the relay apparatus, and in response, the destination apparatus can again transmit the information (related parameter) to the source apparatus via the relay apparatus.

When a relay link is used, the source device transmits a data packet to the relay device within a first period, and transmits the data packet so that it can receive up to an ACK after SIFS (Short Inter-Frame Space). If the source device transmits only one MAC Service Data Unit (MSDU), it is appropriate to set the value of MSDU + SIFS + ACK + SIFS equal to the value of the first period.

Also, the relay apparatus can likewise receive and encode the size of the packet to be sent to the destination apparatus in the second period, and can take into account the ACK to be received after SIFS. Assuming that only one MSDU is transmitted in the relay apparatus, it is appropriate that the value of MSDU + SIFS + ACK + SIFS is equal to the value of the second period.

As described above, the ACK in the second period is transmitted to the destination apparatus by the relay apparatus, so that the relay apparatus can know the status of the link RD. However, (RD) can not be known.

Accordingly, the source apparatus can request the relay apparatus to transmit information on whether the frame has been transmitted well on the R-D link by transmitting a relay acknowledge frame to the relay apparatus in the next first period as shown in [Table 1]. In addition, the relay device can transmit the relay arc fair frame shown in Table 2 to the source device in response to the relay arc request frame.

At this time, the formats of the two frames (Relay ACK Request and Relay ACK Response) are the same as those of Table 1 and Table 2, in which a BlockAck is requested and a BlockAck is sent.

Through the exchange of relay acknowledgment and relay acknowledgment frames, the source device can verify that the data (frame) has been successfully delivered to the destination device. In addition, since the source device must complete the transmission for the data (frame) in the reserved resource, it is necessary to leave time for exchanging this data frame in the last first cycle so that the transmission acknowledgment for that frame becomes the next reservation interval Do not go over.

Also, when operating in a half duplex (HD) relay mode different from the full duplex (FD) relay scheme, the link switching operation of the source device may be changed depending on which one of the direct link and the relay link is used.

When a direct link is used, the source device performs link switching in units of link change intervals as in the full duplex (FD) relay method, but operates through the first period and the second period when the relay link is used. When the source device switches the link from the direct link to the relay link (i.e., the moment the link change interval starts), the first period begins.

The source apparatus delivers the data frame to the destination apparatus according to the first period and the second period. If the source device does not receive an acknowledgment (ACK) or a relay acknowledgment frame received in the first period, the relay device considers that the relay link is blocked and can switch to the direct link.

Since the link device performs link switching when it sends data, the source device can switch to the direct link immediately after the start of the first period after determining the link switching. The link change interval starts from when the source device switches the link to the direct link, and can operate using the link.

The destination apparatus can not know whether or not the source apparatus has determined link switching and can only know that the data (frame) to be received has not yet been received. Therefore, the destination device must periodically check whether the source device has performed link switching.

Since the time when the source device transmits the data frame when using the relay link is the first period, the destination device waits for the data (frame) from the direction toward the direct link every first period.

At this time, the time that the destination apparatus waits can be arbitrarily set by the source apparatus.

Since the source apparatus transmits unconditionally data (frame) at the start of the first period at the time of link switching, the waiting time of the destination apparatus can be set to, for example, about the data sensing time.

If the data (frame) is received via the direct link, the destination device can recognize that link switching has occurred and continue to use the direct link. In this case, the link change interval and the data sensing time are used again.

However, if the data (frame) is not received via the direct link, the destination apparatus aligns the antenna in the direction toward the relay apparatus from the beginning of the second period, and switches to the relay link to wait for data (frame).

Hereinafter, the data exchange rules to be followed by the source device, the relay device, and the destination device in the allocated resource will be described.

The values of the Link Change Interval, Data Sensing Time, First Period, and Second Period described above are determined by the source apparatus in the same manner as the relay use mode values .

The resource (time interval) allocated to each of the source device and the destination device is started by either the link change interval or the first period, and the source device, the relay device, and the destination device participating in the relay operation within one link change interval Nation devices shall use only the same link.

The new link change interval starts immediately after the previous link change interval, but should not exceed the range of resources allocated to each device.

In the normal mode, the source device must initiate frame transmission to the destination device using the direct link at the beginning of the first resource (time interval) allocated to the source device and the destination device. At the start of all subsequent allocated resources, the link that was last successfully used during frame transmission must be used.

On the contrary, in the alternate mode, the source apparatus alternately uses the direct link and the relay link and transmits data to the destination apparatus. At this time, the source device must exchange the link that transmits the frame at the beginning of each link change interval.

If an ACK or BlockAck expected for a frame delivered via a direct link is not received during one link change interval, the source device must switch the link for frame transmission at the beginning of the next link change interval, The frame should be delivered to the destination device using the relay of the device.

Also, if an ACK or BlockAck expected for a frame delivered over a relay link is not received during one link change interval or first period, then the source device will transmit the next link change interval or frame transmission at the beginning of the first period The link must be switched. At this time, the source device must transmit the frame to the destination device using the direct link.

Hereinafter, frame transmission rules to be added when an AF relay apparatus using a full duplex (FD) relay scheme is used in addition to the general rules described above will be described.

4 is a diagram for explaining frame transmission rules added when data is transmitted using an AF relay apparatus using a full duplex (FD) relay scheme according to an embodiment of the present invention.

If the source device has decided to switch the link at the beginning of the next link change interval and assumes that the normal mode is used as the operating mode, the source device should start transmitting the frame after the data sensing time at the beginning of the next link change interval do.

If an exchange mode is used, the source device should alternate the link used for frame transmission at the beginning of each link change interval, and the data sensing time is ignored.

If the destination device in the normal mode does not receive an available frame from the source device within the data sensing time at the beginning of the link change interval, the destination device immediately switches the link to try to receive the frame from the source device via the relay device shall.

If the More Data field of the last received frame is set to '0', the destination device should not switch the link to the next link change interval even if it did not receive the frame during the data sensing time. Here, the More Data field will be described with reference to FIG. 5 is a diagram illustrating a frame structure of an 802.11 WLAN used in an embodiment of the present invention.

If the data frame is not received in the originally expected order in the exchange mode (for example, when a frame to be received on the previous link is not received and a frame of the previous link is received on the switched link of the next link change interval) The device remains on the current link and does not exchange links.

If the More Data field of the last received frame is set to '0', the destination device does not switch the link at the next link change interval.

If the source device wishes to use either a direct link or a relay link and re-exchange the frame transmission, the source device may send data to the destination device at the next link change interval to inform the destination device that it wants to re- The frame should be transmitted after time. This is the only example in which data sensing time is used in exchange mode.

Hereinafter, frame transmission rules to be added when a DF relay apparatus using a half duplex (HD) relay scheme is used in addition to the general rules described above will be described.

FIG. 6 is a diagram illustrating frame transmission rules added when data is transmitted using a DF (Decode and Forward) relay apparatus using a half duplex (HD) relay scheme according to an embodiment of the present invention.

If the relay device operates as a DF relay device using a half duplex (HD) relaying scheme and is in use of the exchange mode, the frame exchange is performed as long as the relay device is used (in other words, the relay link is used) It is repeated and performed during two periods of the cycle.

In the first cycle, the source device transmits a frame to the relay device and the relay device must respond to the source device in SIFS if necessary. In the second cycle, the relay device relays the frame received from the source device to the destination device, and the destination device must respond to the relay device in SIFS if necessary. At this time, the size of the first period and the second period may be the most recently transmitted value.

The first period and the second period are valid only when the source apparatus and the destination apparatus exchange frames via the relay apparatus (that is, when the relay link is used), and the link change interval indicates that the source apparatus and the destination apparatus are direct This is valid only when exchanging frames with a link.

When switching from the direct link to the relay link occurs, the first period starts at the end of the link change interval. Also, when switching from the relay link to the direct link occurs, the link change interval starts from the end of the second period.

The source apparatus can transmit a Relay ACK Request frame as shown in Table 1 to the relay apparatus in order to confirm whether all the frames transmitted through the relay apparatus have been successfully transmitted to the destination apparatus.

The relay apparatus that has received the Relay ACK Request frame must respond to the source apparatus with a Relay ACK Response frame. The relay apparatus transmits a Relay ACK Request frame to the relay apparatus in order to indicate which frame has been successfully received. The BlockAck Bitmap field of the Relay ACK Response frame must be set.

If the source device has decided to switch the link from the direct link to the relay link at the beginning of the next link change interval, the source device should start frame transmission at the beginning of the next link change interval.

Assume that the link currently in use is a direct link and the destination device has not received an available frame from the source device within the data sensing time at the beginning of every link change interval. Then, the destination apparatus should switch the link and it can be seen that the first cycle starts at the start of the corresponding link change interval.

If switching from the relay link to the direct link occurs, the link change interval is initiated at the end of the second period, at which time the source device can initiate the transmission of the data (frame) using the direct link.

The destination apparatus should switch to the direct link every first period and listen to the medium towards the source apparatus. If the destination device has received an available frame from the source device, the destination device should remain on the direct link and assume that the link change interval begins at the beginning of the first period.

Otherwise, the destination device should switch the link at the beginning of the next second period and attempt to receive the frame via the relay device.

If the Relay link is in use and the More Date field of the most recently received frame from the relay device is set to '0', the destination device should not switch to the direct link even though it did not receive any frames during the second period .

An AF relay apparatus using a full duplex (FD) relay system in comparison with a DF relay apparatus using a half duplex (HD) relay system that operates in the same manner as a general apparatus must follow the following points for relay operation.

An AF relay apparatus using a full duplex (FD) relay scheme in an allocated resource operates in an amplify-and-forward manner.

Here, the amplify-and-forward scheme is a scheme in which, for each frame detected in a radio frequency (RF) in a reception state in a resource operating as an AF relay apparatus using the full duplex (FD) Means amplifying one signal and retransmitting it at the same time via another radio frequency in the transmitting state at the same time.

The AF relay device using the full duplex (FD) relay method at the beginning of the allocated resource must initialize the RF module toward the source device to the reception state and initialize another RF module directed to the destination device to the transmission state.

The AF relay apparatus using the full duplex (FD) relay scheme for each frame received should switch the state of each RF module from the transmission mode to the reception mode or vice versa according to the type of frame and the ACK policy .

After link switching occurs, the source device can periodically monitor the quality of the previous link. For this purpose, the source apparatus can use the above-described frame exchange rule.

If the link before the switching is a direct link, the source apparatus can acquire information on the channel state using a link adaptation mechanism that is used in the past. However, if the previous link is a relay link, the source device uses the existing link adaptation mechanism, but additionally requires:

(R-D) link state information to an existing method of transmitting the state information of the source-relay (S-R) link when the relay apparatus responds to the channel status to the source apparatus.

If the channel status of the previous link is better than the status of the link currently in use, the source device can switch to the previous link.

The above-described methods may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy 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 high-level language code that can be executed by a computer using an interpreter or the like. 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.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be construed as being limited to the embodiments described, but should be determined by equivalents to the appended claims, as well as the appended claims.

.

Claims (39)

Detecting a state of a first link directly connected to the destination apparatus from the source apparatus or a second link connected from the source apparatus to the destination apparatus via the relay apparatus;
Selecting either one of the first link and the second link based on states of the first link and the second link;
Transmitting data using the selected link; And
Transmitting information on an operation mode used for transmitting the data to the destination apparatus and the relay apparatus and relaying method of the relay apparatus
Lt; / RTI >
The operating mode
A normal mode in which the data is transmitted to the destination device using the one of the links until it is determined that the link of either the first link or the second link is not available,
At least one of an alternation mode for alternately using the first link and the second link and transmitting the data to the destination apparatus at each start time of a predetermined link change interval, The method comprising the steps of: The method according to claim 1,
Wherein the step of selecting any one of the first link and the second link comprises:
And switching any one of the first link and the second link to the selected link in a link change interval preset based on the detection result. The method according to claim 1,
Switching to the unselected link periodically to monitor the quality of the unselected link of the first link or the second link
Further comprising the steps of: The method of claim 3,
Transmitting a request frame for monitoring the quality of the first link to the relay device when switching from the first link to the second link; And
Receiving a response frame including information about the quality of the first link in response to the request frame
The method comprising the steps of: The method of claim 3,
Transmitting a request frame for monitoring the quality of a link between the source device and the relay device of the second link to the relay device when switching from the second link to the first link; And
In response to the request frame, information about a quality of a link between the source apparatus and the relay apparatus of the second link, and a link between the relay apparatus and the destination apparatus received from the destination apparatus ≪ RTI ID = 0.0 > receiving < / RTI >
The method comprising the steps of: delete delete 3. The method of claim 2,
Wherein the step of selecting any one of the first link and the second link comprises:
Switching the selected link to a non-selected link in a next link change interval of a link change interval to which the confirmed moment is invalid if it is determined that the first link or the second link is not valid
The method comprising the steps of: 3. The method of claim 2,
Wherein the step of switching any one of the first link and the second link to the selected link comprises:
Adjusting the directional antenna direction of the source apparatus according to the result of the beamforming acquired in advance through the unselected link to increase the transmit antenna gain of the data through the unselected link
The method comprising the steps of: 3. The method of claim 2,
And a data sensing time for detecting whether or not the predetermined link change interval or the destination link has transmitted data through the selected link to the destination link and the relay Steps to notify the device
The method comprising the steps of: 3. The method of claim 2,
The step of transmitting data using the selected link
A data sensing time for sensing whether data has been transmitted through the selected link by the destination device or a data sensing time for detecting a switching time required for the destination device to switch to a non- and transmitting the data using the selected link after a period of time considering time. delete delete delete delete The method according to claim 1,
If the source device has decided to resume transmission of the data according to the exchange mode,
Transmitting the data after the data sensing time of the next link change interval of the link change interval to inform the destination device that the operation on the selected link has resumed;
The method comprising the steps of: The method according to claim 1,
Transmitting a request frame to the relay device connected to the second link to determine whether data received by the relay device has been delivered to the destination device; And
Receiving, in response to the request frame, a response frame indicating whether the data has been delivered from the relay device to the destination device
The method comprising the steps of: Determining whether a link selected by the source apparatus is valid among a first link directly connected to the destination apparatus from the source apparatus or a second link connected from the source apparatus to the destination apparatus via the relay apparatus; And
Receiving data based on the determination result
Lt; / RTI >
The mode of operation used to transmit the data includes,
A normal mode in which the data is transmitted to the destination device using the one of the links until it is determined that the link of either the first link or the second link is not available,
At least one of an alternation mode for alternately using the first link and the second link and transmitting the data to the destination apparatus at each start time of a predetermined link change interval, And a communication unit that communicates with the destination apparatus. 19. The method of claim 18,
Wherein the step of determining whether the link selected by the source apparatus is valid
Whether or not the selected link is valid according to whether or not the data is received through the selected link for a period of time from the start of a link change interval interval to a time when a data sensing time elapses And determining whether or not the destination is a destination. 19. The method of claim 18,
The step of receiving the data based on the determination result
Determining whether the source device has switched to the selected link; And
Waiting for reception of the data by directing the directional antenna of the destination apparatus toward the selected link when it is confirmed that the source apparatus has switched to the selected link
A communication method of a destination apparatus including 20. The method of claim 19,
Switching the link of the destination device from the second link to the first link at the start of every first period to confirm whether the source device switches from the second link to the first link; And
If the valid data is not received from the source apparatus via the first link, the link of the destination apparatus at the start of the next second period of the next first period and the next second period, Switching to a link
Further comprising:
Wherein the source device transmits data to the relay device in the next first period, and the relay device transmits data to the destination device in the next second period. 22. The method of claim 21,
Wherein switching the link of the destination from the second link to the first link at the beginning of the first period comprises:
When valid data is received from the source apparatus through the first link, considering that the link change interval starts from a start point of a first period of receiving data on the first link
And a communication unit that communicates with the destination apparatus. 19. The method of claim 18,
Receiving information about an operation mode used for transmitting the data from the source apparatus and a relay scheme of the relay apparatus
Further comprising the steps of: delete delete delete delete delete delete delete delete delete delete When the source device selects the second link among the first link, which is directly connected from the source device to the destination device, and the second one, which is connected to the destination device via the relay device, Waiting for data reception from the source apparatus at a start point of a set link change interval; And
Transmitting the data to the destination device
Lt; / RTI >
The mode of operation used to transmit the data includes,
A normal mode in which the data is transmitted to the destination device using the one of the links until it is determined that the link of either the first link or the second link is not available,
At least one of an alternation mode for alternately using the first link and the second link and for transmitting the data to the destination apparatus every starting time of the predetermined link change interval, Wherein the relay device includes a plurality of relay devices. 35. The method of claim 34,
The step of waiting for data reception from the source apparatus
And adjusting the direction of the directional antenna of the relay apparatus for a predetermined period of time from a start point of the predetermined link change interval to wait for data reception from the source apparatus in the second link. 35. The method of claim 34,
Receiving information from the source apparatus about a first period for a relay link between the source apparatus and the relay apparatus and a second period for a relay link between the relay apparatus and the destination apparatus;
Receiving the data from the source apparatus in the first period; And
And transmitting the data to the destination device in the second period
And a relay device for relaying the relay device. 35. The method of claim 34,
Receiving a request frame from the source apparatus to determine whether data transmitted from the source apparatus to the relay apparatus has been delivered to the destination apparatus; And
In response to the request frame, transmitting a response frame indicating whether the data has been delivered to the destination device
And a relay device for relaying the relay device. delete delete

Images