KR102016066B1 - Method and apparatus for transmitting relay frame in wireless communication system - Google Patents

Abstract

Provided are a method and apparatus for transmitting a relay frame at a relay stage of a wireless communication system. The method includes receiving a relay request frame from a transmitting end requesting to transmit data to a receiving end, transmitting a relay response frame including information about data to be relayed to the transmitting end and the receiving end, respectively, and transmitting data from the transmitting end. Receiving and generating a relay frame including the data and transmitting to the receiving end. According to the present invention, wireless LAN service coverage can be extended by transmitting data to a receiving end outside the transmitting end of the transmitting end, and communication with the receiving end is performed at a transmitting end that cannot directly connect with the receiving end by using an adjacent terminal connected to the receiving end as a relay end. can do.

Description

Method and apparatus for transmitting relay frame in wireless communication system {METHOD AND APPARATUS FOR TRANSMITTING RELAY FRAME IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a wireless communication system, and more particularly to a wireless communication using a relay technology.

Wireless local area network (LAN) technology is in the spotlight as a wireless communication technology that provides high-speed data service in an unlicensed band. Unlike conventional cellular systems, access points (APs), which act as base stations, operate when only a wired network and a power supply are connected, so that anyone can easily install and communicate data at low cost.

The decentralized operation of wireless LAN technology has the advantage of simplicity and is spreading to sensor networks and smart utility networks. In the case of sensor networks and smart utility networks, the service coverage is more important than the increase in transmission speed because there is not much data to transmit and the transmission cycle is short.

Most wireless LAN transmission standards have evolved to use multiple antennas or to increase bandwidth to improve transmission speed. Representative examples are Institute of Electrical and Electronics Engineers (IEEE) 802.11n and IEEE 802.11ac standards. However, in the general network environment, such improvement in transmission speed has a great meaning of increasing network capacity, but in a network for collecting information such as a sensor network, coverage coverage has a greater meaning. If coverage is expanded, a small network can collect information from a large area, so a sensor network can be constructed at low cost.

The coverage expansion schemes adopted by the existing communication systems use a channel coding scheme having a low code rate, a repetition scheme that can be decoded at a low signal-to-noise ratio, or the like. For example, a beamforming technique may be used to allow a high power signal to reach a desired receiver. However, these methods can be a problem in the cost of modifying a lot of physical layer specifications or the use of multiple antennas. Therefore, there is a need for a technique for expanding coverage in a wireless LAN system, particularly a technique for expanding a service area of a wireless LAN using a relay technology.

The relay method is a method in which an idle terminal is used as a relay terminal between a transmitter and a receiver to relay and transmit data received from the transmitter to the receiver. In the 3GPP (3 ^rd Generation Partnership Project) in the LTE (Long Term Evolution) or system, such as the IEEE 802.16 employs a relaying method in a form to perform all of the control in the base station to modify the frame configuration can be obtained effects such as coverage expansion . However, in the case of the wireless LAN, since there is no base station performing the function of centralized control, the relay link is established and the relay transmission is started by using the handshaking method of the wireless LAN. Since the purpose of adding a relay function in a wireless LAN was to improve transmission speed rather than expanding coverage, a handshaking protocol that can be used only when both the relay and the receiver exist within the transmission coverage of the transmitter is defined.

Therefore, there is a need for a method of transmitting data to a receiving end that is outside the transmitting coverage of the transmitting end.

An object of the present invention is to provide a method and apparatus for transmitting a relay frame in a wireless communication system.

Another technical problem of the present invention is to provide a handshaking method for exchanging control frames and data frames for relaying and relay link establishment.

Another technical problem of the present invention is to provide a method and apparatus for configuring a relay frame capable of transmitting data of a transmitter and data of a relay terminal.

An object of the present invention is to extend wireless LA service coverage using the IEEE 802.11 MAC protocol.

According to an aspect of the present invention, a method for transmitting a relay frame in a relay terminal of a wireless communication system includes receiving a relay request frame requesting to transmit data to a receiver, from a transmitter, relay including information on data to be relayed Transmitting a response frame to the transmitting end and the receiving end, receiving data from the transmitting end, and generating a relay frame including the data to transmit to the receiving end.

The relay stage may be at least one terminal or an access point.

The relay terminal may be a terminal selected from among neighboring terminals based on at least one of a magnitude of a signal received by the transmitter, a rate of a received signal, or a destination address.

The method may further include retransmitting a frame including the data to the transmitter, and the frame including the data may include ACK information of the relay terminal.

The method may further include receiving a request to send (RTS) frame from the transmitter, which blocks interference due to signal transmission from neighboring terminals, and transmitting the RTS frame to the receiver.

The relay response frame may include RTS information.

The method may further include receiving a clear-to-send (CTS) frame from the receiving end that is ready to receive data, and transmitting the CTS frame to the transmitting end.

The method may further include receiving an ACK frame indicating that the data is successfully received from the receiving end and transmitting the ACK frame to the transmitting end.

The relay request frame may be transmitted when the receiving end is outside the transmission area of the transmitting end.

When no beacon frame is transmitted between the transmitter and the receiver, it may be determined that the receiver is outside the transmission area of the transmitter.

The relay frame may be a frame of IEEE (Institute Electrical and Electronics Engineers) 802.11a / g standard.

The relay frame may be configured by completely demodulating and remodulating the data or the relay request frame.

The relay frame may further include data of the relay itself to be transmitted to the receiver.

The relay frame may be configured by gain adjustment and carrier frequency offset compensation of the data or the relay request frame.

The relay frame may further include data of the relay itself to be transmitted to the receiver.

The data and the data of the relay itself may each include a start address, a destination address, and length information according to a MAC (Media Access Control) frame format.

According to another aspect of the present invention, in a wireless communication system, a terminal that transmits a relay frame may include a relay unit including a receiver for receiving a relay request frame requesting data transmission from a transmitter, and information about which data to relay; And a transmitter for transmitting a frame to the transmitter and the receiver, respectively, wherein the receiver receives data from the transmitter, and the transmitter transmits a relay frame including the data to the receiver.

According to the present invention, wireless LAN service coverage can be extended by transmitting data to a receiving end that is outside the transmitting coverage of the transmitting end.

According to the present invention, by using an adjacent terminal connected to the receiving end as a relay terminal, the transmitting end can not communicate with the receiving end can not be directly connected to the receiving end.

1 shows an example of a wireless communication system for transmitting a signal using a relay.
Figure 2 shows another example of a wireless communication system for transmitting a signal using a relay stage.
3 is a flowchart illustrating an example of a handshaking process of transmitting and receiving a frame between a transmitting end, a receiving end, and a relay in a wireless communication system in which a transmitting end is located outside a transmission area of a receiving end according to the present invention.
4 is a flowchart illustrating another example of a handshaking process of exchanging frames between a transmitter, a receiver, and a relay according to the present invention.
5 is a diagram illustrating an example of a structure of a physical layer relay frame according to the present invention.
6 is a view showing another example of the structure of a physical layer relay frame according to the present invention.
7 is a flowchart illustrating an example of an operation of a transmitter for transmitting a frame according to the present invention.
8 is a flowchart illustrating an example of an operation of a relay stage for relaying a frame according to the present invention.
9 is a flowchart illustrating an example of an operation of a receiving end relaying a frame according to the present invention.
10 is a block diagram illustrating an example of a wireless communication system for performing a relay operation according to the present invention.

1 shows an example of a wireless communication system for transmitting a signal using a relay.

Referring to FIG. 1, the wireless communication system includes a transmitter 110, a relay 120, and a receiver 130.

The receiving end 130 is located outside the transmission area 111 of the transmitting end. The transmission area (or coverage) of the transmitter 110 refers to a spatial area capable of demodulation at the receiver 130 when a frame is transmitted at the minimum transmission rate. The relay terminal 120 exists in a common area of the transmitter 110 and the receiver 130. Therefore, both the transmitting end 110 and the receiving end 130 are included in the transmission area 121 of the relay end 120.

The transmitter 110 transmits a signal to the relay terminal 120 in order to transmit a signal to the receiver 130, and the relay terminal 120 transmits the signal of the received transmitter 110 to the receiver 130.

Figure 2 shows another example of a wireless communication system for transmitting a signal using a relay stage.

Referring to FIG. 2, the wireless communication system includes a transmitter 210, a relay 220, and a receiver 230.

The relay terminal 220 and the receiver 230 both exist in the transmission area 211 of the transmitter. However, the distance between the transmitter 210 and the receiver 230 is far compared to the distance between the relay 220 and the transmitter 230. The transmitting end 210 may transmit to the relay terminal 220 at a transmission rate of 11 Mbps, but the transmitting end 210 may transmit to the receiving terminal 230 at a transmission rate of 2 Mbps. The relay terminal 220 may transmit a transmission rate of 5.5 Mbps to the receiver 230.

Therefore, the transmitting end 210 transmits a signal to the receiving end 230 via the relay end 220 more efficiently than the direct transmitting signal from the transmitting end 210 to the receiving end 230. If it is calculated without considering the overhead of the physical layer and the MAC layer, the transmitting end 210 passes through the receiving end 220 through the relay end 220 at a transmission rate of 8.25 Mbps (= (11 + 5.5) / 2) on average. 230 may transmit a signal.

As shown in FIG. 2, when the receiving end and the relay end are within the transmission area of the transmitting end, all terminals receive a Request-To-Send (RTS) and a Clear-To-Send (CTS), which are a kind of control frame for securing a right to use a channel Although the handshaking process for establishing the relay link is relatively easy since the reception is possible, as shown in FIG. 1, if the receiver is outside the transmission area of the transmitter and the receiver is outside the transmission area of the transmitter, the handshaking process for the relay link is complicated. Do.

Meanwhile, the present invention is applicable to both the wireless communication system as shown in FIG. 1 and the wireless communication system as shown in FIG.

3 is a flowchart illustrating an example of a handshaking process of transmitting and receiving a frame between a transmitting end, a receiving end, and a relaying end in a wireless communication system in which a transmitting end is located outside a transmission area of a receiving end according to the present invention. Only one example of a process of transmitting one data frame to the receiving end is shown in the transmitting end, and a plurality of data frames may be transmitted at a short inter frame space (SIFS) interval. Meanwhile, the transmitting end, the receiving end, and the relaying end may each be an access point (AP).

Referring to FIG. 3, an attempt is made to establish a relay link between a transmitter and a receiver (S300). If the transmitting end is outside the transmitting area of the receiving end, the transmitting end may not receive a control frame (eg, a beacon frame) periodically transmitted by the receiving end. So, in the existing wireless LAN (Local Access Network) it is not possible to configure a Basic Service Set (BSS). At this time, the transmitting end determines that there is no connectable receiving end.

The transmitting end searches for and selects the relay end (S305). Although the transmitting end may not receive the control frame periodically transmitted by the receiving end, it may be possible to receive a frame transmitted to other receiving terminals (or APs) to the receiving end. Other terminals (or APs) in the vicinity may be candidates for the relay terminal. The transmitting end selects one of the other terminals (or APs) in the vicinity as the relay end. For example, the transmitter selects a relay terminal from among the other terminals (or APs) in the vicinity based on at least one of the size of the received signal, a rate of the received signal, or a destination address.

The transmitting end requests the relay transmission by transmitting a relay request frame to the selected relay end (S310). Upon receiving the relay request, the relay terminal determines whether relay transmission is possible to the receiver. Whether to accept the relay transmission may be determined based on whether the relay transmission is performed for a queue state, a power state, or another terminal of the relay terminal or the receiving terminal.

If it is possible to relay transmission from the relay stage to the receiver, the relay stage transmits a relay response frame to the transmitter and the receiver, respectively, to respond to the relay transmission (S315).

The transmitting end receiving the relay response confirms that the relay transmission can be performed, and the receiving end receiving the relay response can also confirm which transmitting terminal the relay terminal will relay.

In this case, the transmitting end may repeat the relay request until a relay response is received from the relay to accept the relay transmission.

The transmitting end transmits a Request-To-Send (RTS) frame (or RTS information) to the relay in order to block the interference due to transmission of neighboring terminals in advance (S320), and the relay also transmits an RTS frame (or RTS information). ) Is transmitted to the receiving end (S325).

The receiving end is ready to receive data and transmits a clear-to-send (CTS) frame (or CTS information) to allow the transmission (S330), and the intermediate end receives the CTS frame (or CTS information) to the receiving end. It transmits (S335). Through the above processes, the transmitting end can be guaranteed an opportunity to transmit data without interference or interference to the receiving end.

The transmitting end transmits the data frame to the relay end (S340), and the relay end transmits the data frame to the receiving end (S345). At this time, if the data frame transmitted by the relay to the receiver is also transmitted to the transmitter, the data frame serves as an acknowledgment (ACK) for the relay to receive the data frame from the transmitter.

The receiving end receiving the data frame transmits the ACK frame to the relay stage (S350), and the relay stage transmits the ACK frame to the transmitter stage (S355). This is a process of confirming that the receiving end receives the data frame transmitted from the transmitting end.

According to the present invention, the data transmission speed between the transmitting end and the receiving end is lowered, but the server coverage of the wireless LAN is increased. Therefore, it is useful in application of a sensor network requiring wide coverage rather than high transmission speed.

4 is a flowchart illustrating another example of a handshaking process of exchanging frames between a transmitter, a receiver, and a relay according to the present invention. Here, only the process of transmitting one data frame to the receiving end is shown, but this is an example according to the present invention, and a plurality of data frames may be transmitted at SIFS intervals. The transmitting end, the receiving end, and the relaying end may each be APs.

Referring to FIG. 4, an attempt is made to establish a relay link between a transmitter and a receiver (S400). Since the transmitting end is outside the transmission area of the receiving end, if the receiving end cannot receive the control frame (for example, beacon frame) periodically transmitted, the existing wireless LAN does not configure BSS. At this time, the transmitting end determines that there is no connectable receiving end.

The transmitting end searches for and selects a relay end (S405). Although the transmitting end may not receive the control frame periodically transmitted by the receiving end, other terminals (or APs) in the vicinity may be able to receive the frame transmitting to the receiving end. Other terminals (or APs) in the vicinity may be candidates for the relay terminal. The transmitting end selects one of the other terminals (or APs) in the vicinity as the relay end. For example, the transmitter selects a relay terminal from among other terminals (or APs) in the vicinity based on at least one of the size of the received signal, the transmission rate of the received signal, or the destination address.

The transmitter sends a relay request frame to the selected relay terminal to request relay transmission (S410). In this case, the relay request frame may include information of the RTS frame in order to prevent the collision by blocking the interference due to the transmission of the neighboring terminals in advance. Therefore, it is not necessary to transmit a separate RTS frame. Upon receiving the relay request, the relay terminal determines whether relay transmission is possible to the receiver. Whether to accept the relay transmission may be determined based on whether the relay transmission is performed for a queue state, a power state, or another terminal of the relay terminal or the receiving terminal.

If it is possible to relay transmission from the relay stage to the receiver, the relay stage transmits the relay response frame to the transmitter and the receiver, respectively, to respond to the relay transmission (S415). In this case, the relay response frame may include information of the RTS frame in order to prevent the collision by blocking the interference due to the transmission of the neighboring terminals in advance. In this case, it is not necessary to transmit a separate RTS frame.

The receiving end receiving the relay response confirms that the relay transmission can be performed, and the receiving end receiving the relay response can know which transmitting terminal the relay terminal will transmit data.

In this case, the relay request of the transmitter may be repeated until a relay response is received from the relay to accept the relay transmission.

The receiving end is ready to receive data and transmits a CTS frame allowing the transmission to the relaying step (S420), and the relaying step transmits the CTS frame to the receiving end (S425). Through the above processes, the transmitting end is guaranteed an opportunity to transmit data to the receiving end.

The transmitting end transmits the data frame to the relay stage (S430), and the relay stage generates a relay frame including the data frame and transmits it to the receiving stage (S435). At this time, if the data frame transmitted from the relay terminal to the receiver is also transmitted to the transmitter, the data frame serves as an ACK for the relay terminal to receive the data frame.

The receiving end receiving the data frame transmits the ACK frame to the relay stage (S440), and the relay stage transmits the ACK frame to the transmitter stage (S445). This is a process of confirming that the receiving end receives the data frame transmitted from the transmitting end.

As another example, similar to FIG. 4, a relay link may be formed by defining a frame including both the functions of the relay response frame and the CTS frame.

Now, a method for generating a relay frame at the relay stage according to the present invention will be described.

There are two cases of the structure of the relay frame. A relay frame (Example 1) in which the relay stage completely demodulates and modulates a frame received from the transmitter, and a relay frame configured by compensating gain adjustment and carrier frequency offset without completely demodulating the frame received from the transmitter in the relay stage ( Example 2). In addition, for each embodiment, there are cases where the data of the relay itself to be transmitted from the relay to the receiver is included or not included.

5 is a diagram illustrating an example of a structure of a physical layer relay frame according to the present invention. After the relay demodulates all the received data, the relay frame reconstructs the data including the data to be delivered to the receiver according to the situation.

Referring to FIG. 5, the demodulation and demodulation of the received frame has a physical layer frame structure having the same structure as that of the non-meter frame.

The relay frame may be configured using a frame structure of IEEE 802.11a / g.

In addition, (a) of FIG. 5 is a relay frame including only the data field DATA1 to be relayed because there is no data to be transmitted from the relay, and FIG. 5 (b) shows the data field DATA1 to be relayed and the relay itself. This relay frame includes all of the data fields DATA2.

The relay frames of FIGS. 5A and 5B all include a short training field (STF), a long training field (LTF), and a signal field (SIG).

STF includes information related to packet detection, information on automatic gain control (AGC), information on coarse carrier frequency offset (CFO), or information on time synchronization. At least one.

The LTF includes fine carrier offset estimation related information or channel estimation related information.

The signal field includes a rate or length information. The rate may be a transmission rate.

The data field DATA1 to be relayed has a payload in which a source address is a transmitting end and a destination address is a receiving end, and the data field DATA2 of the relay itself has a starting address as a relay. And there is a payload whose destination address is the receiving end. As such, the data fields DATA1 and DATA2 may include a starting address, a destination address, and length information in each payload according to a MAC frame format for each data. Through this, it is possible to distinguish whether the data among the two data is the relay data of the transmitter or the transmission data of the relay terminal.

6 is a view showing another example of the structure of a physical layer relay frame according to the present invention. The relay frame is a relay frame configured not to demodulate all received data to be relayed, but to transmit the data to be relayed first, and then to transmit the received data to be relayed after compensating the carrier frequency offset. The reason for estimating and compensating the carrier frequency offset in case that the receiving frame does not demodulate all the received frames is that the sum of the two carrier frequency offsets between the transmitting end-relay and the receiving end can be estimated in the existing STF and LTF structures This is because the carrier frequency offset may be out of range.

Referring to FIG. 6, (a) of FIG. 6 is a relay frame including only the data field DATA1 to be relayed because there is no data to be transmitted in the relay stage, and FIG. 6 (b) is a data field DATA1 to be relayed. And a relay frame including all of its own data field DATA2.

The relay frame of FIG. 6A includes an STF. The STF includes at least one of packet detection related information, AGC related information, coarse carrier frequency offset estimation information, or time synchronization related information. The STF is a STF received by the relay from the transmitter, and is used for packet detection and AGC in the relay, and thus, when the STF is transmitted as it is, the length and waveform may not be constant. Therefore, the relay does not relay the STF.

In addition, the relay frame includes a CFO corrected version packet consisting of an R-LTF, an R-SIG field, and a DATA1 field. This is a version that compensates for the carrier frequency offset (CFO) in the received data transmitted from the transmitter to the transmitter. Specifically, packet detection and AGC are performed for frame reception, and carrier frequency error (CFO) is estimated using STF and LTF. It also matches time synchronization (the process of finding the starting point of the LTF). The carrier frequency offset is compensated over the total received frames based on the estimated carrier frequency offset. Then, only the SIG field is demodulated or the end of the frame is predicted based on the received power to calculate the number of OFDM symbols in OFDM symbol units.

This compensates for the carrier frequency offset of the LTF, the signal field, and the data field to be transmitted from the transmitter to the receiver, but does not include the STF in this relay part.

6 (b) is a relay frame to which the data field of the relay node itself is to be transmitted. Accordingly, the relay frame of FIG. 6 (b) includes the LTF, SIG1 field, in FIG. 6 (a). SIG2 field and DATA2 field are further included.

Although the SIG1 field includes rate information and length information as in the signal field of FIG. 5, this is set to delay transmission of other terminals until the end of the frame separately from the data to be transmitted. Therefore, rate information is fixed at a specific rate and length information is set equal to the length of the entire relay frame. The function of disabling the channel while other terminals look at the SIG1 field while the relay frame is transmitted is called spoofing. Used in the IEEE 802.11 standard.

The SIG2 field contains rate information and length information for the actual data field that the relay sends to the receiver.

The DATA2 field is a field that contains data of the relay itself.

After the DATA2 field, a new frame structure starting from the R-LTF is connected again, which is a form in which a relay compensates for a Carrier Frequency Offset (CFO) after receiving a frame from a transmitter. . The carrier frequency offset is compensated over the total received frames based on the estimated carrier frequency offset. Only the signal field is demodulated or the end of the frame is predicted based on the received power to calculate the number of OFDM symbols in OFDM symbols.

When the relay frame includes the carrier frequency offset-compensated frame and the length information of the reception frame and there is data to be transmitted from the relay stage to the receiver, the length of the relay data is calculated based on the data, data rate, and length.

The total length of the relay frame can be calculated based on the calculated length of the received frame and the length of the relay data. Based on this, rate information and length information of the SIG1 field are configured. For example, the rate information may be fixed at one rate, and then only length information may be set to match the total frame length.

The DATA2 field may be demodulated through the rate information and the length information of the DATA2 field transmitted from the relay stage included in the SIG2 field to the receiver.

The relay stage performs demodulation on the DATA2 field and then starts demodulation on DATA1 transmitted from the transmitter to the receiver. First, the carrier frequency is estimated / compensated based on the R-LTF, and the channel is estimated. Based on this, rate information and length information are extracted by demodulating the R-SIGNAL field, and demodulating DATA1 using this.

The present invention proposes a method of extending a wireless LAN service area based on the existing IEEE 802.11 MAC protocol and a physical layer standard. In particular, the IEEE 802.11a / g OFDM physical layer is described with an example, but the scope of the present invention is not limited to this, it can be applied to other physical layer standards other than IEEE 802.11n, IEEE 802.11ac.

7 is a flowchart illustrating an example of an operation of a transmitter for transmitting a frame according to the present invention.

Referring to FIG. 7, the transmitting end attempts to establish a relay link with the receiving end (S700). If the receiving end is located outside the transmission area of the transmitting end, the transmitting end searches for and selects the relaying end (S705).

The transmitter sends a relay request frame to the selected relay (S710). In this case, the transmitting end may receive a relay response transmitted from the relay end to the receiving end as a relay response to the relay request (S715).

The transmitting end transmits the RTS frame to the relay in order to block the interference due to the transmission of the neighboring terminals in advance to prevent the collision (S720). The receiving end is ready to receive data and receives the CTS frame allowing the transmission through the relaying step (S725).

The transmitter transmits data to the relay stage (S730), and when the receiver receives data properly, receives the ACK frame through the relay stage (S735).

Meanwhile, if the RTS frame is included in the relay request frame, the transmission of the RTS frame may be omitted.

8 is a flowchart illustrating an example of an operation of a relay stage for relaying a frame according to the present invention.

Referring to FIG. 8, the relay stage receives a relay request frame from the transmitter (S800). At this time, the relay stage transmits the relay response to the relay request to the receiving terminal (or transmitting terminal) (S805).

The relay stage blocks an interference due to transmission of neighboring terminals in advance to receive an RTS frame to prevent a collision from the transmitter (S810), and transmits the RTS frame to the receiver (S815).

The relay stage is ready to receive data from the receiving end and receives the CTS frame allowing the transmission (S820), and transmits the CTS frame to the transmitting end (S825).

The relay stage receives data from the transmitter (S830), generates a relay frame including the data, and transmits it to the receiver (S835).

When the receiving end properly receives the data, the relay stage receives the ACK frame from the receiving end (S840) and transmits the ACK frame to the transmitting end (S845).

Meanwhile, if the RTS frame is included in the relay request frame, transmitting the RTS frame may be omitted.

9 is a flowchart illustrating an example of an operation of a receiving end relaying a frame according to the present invention.

Referring to FIG. 9, the receiving end transmits and receives a control frame to the transmitting end and attempts to connect a relay link (S900). This is to perform a relay operation when the receiving end is located outside the transmitting area of the transmitting end.

The receiving end may receive a relay response from the relaying end, and may know from which transmitting end to receive data from which transmitting end (S905).

The receiving end receives the RTS frame transmitted by the transmitting end through the relaying step (S910). In response to this, the CTS frame, which is ready to receive data and allows transmission, is transmitted to the relay stage (S915).

Receiving data of the transmitting end from the relay stage (S920), and transmits an ACK frame indicating that the appropriate reception to the relay stage (S925).

10 is a block diagram illustrating an example of a wireless communication system for performing a relay operation according to the present invention.

Referring to FIG. 10, a wireless communication system includes a transmitter 1000, a relay 1030 and a receiver 1060.

The transmitter 1000 includes a transmitter 1005, a receiver 1010, and a processor 1015.

The processor 1015 operates to attempt to establish a relay link with the receiver through the transmitter 1005 and the receiver 1010. When the receiving end is located outside the transmitting area of the transmitting end, the processor 1015 operates to search for and select the relay end. The processor 1015 generates a relay request frame, or an RTS frame.

The transmitter 1005 transmits a relay request frame to the selected relay stage.

The transmitter 1005 transmits the RTS frame to the relay stage in order to prevent collision by preventing interference due to transmission of neighboring terminals in advance. However, if the RTS frame is included in the relay request frame, transmitting the RTS frame may be omitted.

The transmitter 1005 transmits data to the relay stage.

The receiver 1010 may receive a relay response transmitted from the transmitter 1005 to the receiver as a relay response to the relay request.

Receiving unit 1010 receives the CTS frame through the relay stage to allow the transmission is ready to receive the data transmission.

The receiver 1010 receives an ACK frame through the relay stage when the receiver properly receives data.

Meanwhile, the relay stage 1030 includes a transmitter 1035, a receiver 1040, and a processor 1045. The relay stage may be a terminal. Alternatively, the relay stage may be an AP.

The transmitter 1035 transmits a relay response to the relay request to the receiver (or the transmitter).

The transmitter 1035 transmits the RTS frame to the receiver. Meanwhile, if the RTS frame is included in the relay request frame, transmitting the RTS frame may be omitted.

The transmitter 1035 transmits the CTS frame to the transmitter.

The transmitter 1035 transmits a relay frame including data to the receiver.

The transmitter 1035 transmits an ACK frame to the transmitter.

The receiver 1040 receives the relay request frame from the transmitter.

The receiver 1040 receives an RTS frame from the transmitter to prevent collision by blocking interference due to transmission of neighboring terminals in advance.

The receiving unit 1040 is ready to receive data from the receiving end and receives a CTS frame allowing the transmission.

The receiver 1040 receives data from a transmitter.

The receiver 1040 receives an ACK frame from the receiver when the receiver properly receives data.

The processor 1045 generates a relay frame containing data.

Meanwhile, the receiving end 1060 includes a transmitter 1065, a receiver 1070, and a processor 1075.

The processor 1075 operates to transmit and receive a control frame with a transmitting end to attempt a relay link connection. This is to perform a relay operation when the receiving end is located outside the transmitting area of the transmitting end.

Processor 1075 generates a CTS frame, or ACK frame.

The receiver 1070 receives a relay response from the relay stage. It can be known from which transmitting end through which relay to receive data.

The receiver 1070 receives the RTS frame transmitted by the transmitter through the relay.

The receiver 1070 receives a relay frame including data of the transmitter from the relay.

The transmitter 1065 is ready to receive data in response to the RTS, and transmits a CTS frame to the relay stage to allow transmission.

The transmitter 1065 transmits an ACK frame indicating that the data has been properly received to the relay stage.

The processor may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device.

In addition, the transmitting end, the receiving end, and the relaying end may further include a memory in which data is stored, and the memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or the like. It may include a storage device. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in memory and executed by a processor. The memory may be internal or external to the processor and may be coupled to the processor by various well known means.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

Claims (15)

In the method for transmitting a frame at the transmitting end of the wireless communication system,
Transmitting a relay request frame to the relay terminal requesting to transmit data to the receiving end; receiving a relay response frame including information about data to be relayed from the relay end; And
And transmitting data to the relay stage.
The relay response frame is further transmitted to the receiving end,
When the relay stage receives the data from the transmitter, the relay stage generates a relay frame including the data and transmits the data to the receiver.
Based on the relay response frame, information on whether to perform relay transmission is transmitted to the transmitting end.
And information on the transmitting end transmitting the data based on the relay response frame is transmitted to the receiving end.

The method of claim 1,
The transmitting end is a frame transmission method, characterized in that at least one terminal or an access point (Access Point).
The method of claim 1,
The intermediate stage,
And a terminal selected from among neighboring terminals based on at least one of a magnitude of a signal received at the transmitter, a rate of a received signal, and a destination address.
The method of claim 1,
Re-receiving a frame containing the data from the relay stage, further comprising:
The frame including the data comprises the ACK information of the relay stage, frame transmission method.
The method of claim 1,
Transmitting a request to send (RTS) frame to the transmitter to block interference due to signal transmission from neighboring terminals; And
And the relay stage further transmits the RTS frame to the receiver.
The method of claim 1,
And the relay response frame includes RTS information.
The method of claim 1,
The relay stage is ready to receive data and receives a clear-to-send (CTS) frame from the receiver to allow transmission;
Receiving the CTS frame from the relay stage.
The method of claim 1,
Receiving an ACK frame from the receiving end indicating that the relay successfully receives the data,
And receiving the ACK frame from the relay stage.
The method of claim 1,
The relay request frame,
And when the receiving end is outside the transmission area of the transmitting end, the frame transmitting method.
The method of claim 9,
If the beacon frame is not transmitted between the transmitting end and the receiving end, it is determined that the receiving end is outside the transmission area of the transmitting end, frame transmission method.
The method of claim 1,
The relay frame,
And demodulating and remodulating the data or the relay request frame completely.
The method of claim 11,
The relay frame is
The frame transmitting method further comprises the data of the relay itself to be transmitted to the receiving end.
The method of claim 1,
The relay frame,
And adjusting the gain or the carrier frequency offset compensation of the data or the relay request frame.
The method of claim 12,
The data and the data of the relay itself, respectively, characterized in that it comprises a start address, destination address and length information according to the MAC (Media Access Control) frame format, frame transmission method.
In the terminal for transmitting a frame in a wireless communication system,
A transmission unit;
Receiving unit; And
A processor for controlling the transmitter and the receiver,
The processor,
Transmitting a relay request frame to the relay terminal requesting to transmit data to the receiver through the transmitter;
Receiving a relay response frame from the relay stage, the relay response frame including information about data to be relayed through the receiver, and
While transmitting the data to the relay through the transmission unit,
The relay response frame is further transmitted to the receiving end,
When the relay stage receives the data from the terminal, the relay stage generates a relay frame including the data and transmits the data to the receiver.
Information on whether or not to perform relay transmission is transmitted to the terminal based on the relay response frame;
And information on the terminal transmitting the data based on the relay response frame is transmitted to the receiving end.

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