KR101727932B1 - Wireless communication method - Google Patents

Abstract

The present invention relates to a wireless communication method as a wireless communication method about a channel allocation method, in communication according to an orthogonal frequency division multiple access (OFDMA) scheme. The wireless communication method using an OFDMA comprises: a first step in which an access point transmits an RTS signal to a station; a second step in which the station transmits a CTS signal corresponding to the RTS signal; a third step in which the access point transmits downlink data corresponding to the CTS signal; a fourth step in which the access point transmits a trigger frame to the station; and a fifth step in which the station transmits uplink data.

Description

[0001] WIRELESS COMMUNICATION METHOD [0002]

The present invention relates to a wireless communication method, and more particularly, to a wireless communication method for a channel allocation method in communication according to an OFDMA scheme.

With the development of information and communication technology, various wireless communication technologies are being developed. Among them, a wireless local area network (WLAN) may be a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), a smart phone A smart phone, a tablet PC, or the like, to wirelessly connect to the Internet in a home, an enterprise, or a specific service providing area.

The standard for wireless LAN technology is being developed as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The wireless LAN technology according to the IEEE 802.11a standard operates based on an orthogonal frequency division multiplexing (OFDM) scheme and can provide a transmission speed of up to 54 Mbps in the 5 GHz band. The wireless LAN technology according to the IEEE 802.11b standard operates based on a direct sequence spread spectrum (DSSS) scheme and can provide a transmission speed of up to 11 Mbps in the 2.4 GHz band. The wireless LAN technology according to the IEEE 802.11g standard operates based on the OFDM scheme or the DSSS scheme, and can provide a transmission speed of up to 54 Mbps in the 2.4 GHz band.

The wireless LAN technology according to the IEEE 802.11n standard operates in the 2.4 GHz band and the 5 GHz band based on the OFDM scheme. When using the multiple input multiple output (OFDM) and OFDM (MIMO-OFDM) spatial stream) at a transmission rate of up to 300 Mbps. According to the IEEE 802.11n standard, the wireless LAN technology can support a channel bandwidth of up to 40 MHz, which in this case can provide a transmission speed of up to 600 Mbps.

With the spread of WLAN and the diversification of applications using it, there is a need for a new WLAN system to support a higher throughput than the data processing rate supported by IEEE 802.11n. IEEE 802.11ac is a next generation wireless LAN system that supports very high throughput (VHT) in the frequency range below 6 GHz. IEEE 802.11ac supports a minimum throughput of 1 Gbps on multiple stations (STAs) and a maximum throughput of at least 500 Mbps on a link to one STA. In addition, IEEE 802.11ac can support 80 MHz, contiguous 160 MHz, non-contiguous 160 MHz bandwidth, and / or higher bandwidth. In addition, up to 256-QAM (quadrature amplitude modulation) scheme can be applied, and MU (multi-user) -MIMO technology can be supported for higher throughput. For support of MU-MIMO technology in IEEE 802.11ac, STAs may have more than one antenna. IEEE 802.11ac currently supports only DL MU-MIMO. The maximum number of STAs that can transmit packets simultaneously at access points (APs) is four, and when the maximum number of supportable spatial streams is eight, each STA uses up to four spatial streams .

As the spread of the wireless LAN is activated and applications using the wireless LAN have been diversified, there is a growing need for a new wireless communication method supporting a higher transmission speed than the existing wireless LAN technology.

In particular, the Orthogonal Frequency Division Multiple Access (OFDMA) scheme has been designated as a key technology in the physical layer of 802.11ax, the next generation wireless standard.

However, in order to maximize the use of channels in an OBSS (Overlapped Basic Service Set) environment, an access point (AP) needs to know the transmission requirements of the stations in order to determine the contents to be transmitted up- There is a problem that a head is generated. Therefore, there is a need for a method for an access point to allocate a channel for data to be transmitted from a station in a short time.

Korean Patent No. 10-0667178

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the overhead that occurs when an access point allocates a channel for data to be transmitted from a station in a wireless communication method using OFDMA.

Another aspect of the present invention is to provide a wireless communication method using OFDMA in which an access point allocates a channel for data to be transmitted from a station in a short period of time.

A wireless communication method according to the present invention is a wireless communication method using orthogonal frequency division multiple access (OFDMA), comprising: a first step of an access point transmitting an RTS signal to a station; A second step in which the station transmits a CTS signal in response to the RTS signal to the access point; A third step of the access point transmitting down transmission data to the station in response to the CTS signal; A fourth step of the access point transmitting a trigger frame to the station; And a fifth step in which the station transmits uplink transmission data to the access point; Wherein the access point allocates a channel for transmitting the uplink data in response to the CTS signal and transmits the uplink data through the allocated channel using the trigger frame, Is received.

According to another aspect of the present invention, there is provided a wireless communication method using orthogonal frequency division multiple access (OFDMA), wherein a station to transmit data upwardly transmits an RTS signal to an access point through a first channel available to the station A first step of transmitting data; A second step of the access point transmitting a CTS signal to the station on the first channel corresponding to the RTS signal and transmitting a trigger frame to the station on a second channel not overlapping the first channel; A third step in which the station transmits the data up to the access point via the first and second channels; .

1 is a diagram illustrating an embodiment of a wireless communication method according to the present invention.
2 is a view showing another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the terminology used herein is for the purpose of description and should not be interpreted as limiting the scope of the present invention.

The embodiments described in the present specification and the configurations shown in the drawings are preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention and thus various equivalents and modifications Can be.

In wireless communication, Orthogonal Frequency Division Multiple Access (OFDMA) scheme is one of techniques introduced in addition to Full Duplex to improve the performance of a wireless LAN. In the OFDMA scheme, subcarriers are grouped into subchannels, which are larger units, and these subchannels are grouped into channels that can be assigned to wireless users again. Each channel assignment may be changed frame by frame within the modulation order. This makes it possible to dynamically adjust bandwidth usage.

The wireless communication method of the present invention exemplifies the IEEE 802.11 wireless LAN standard. In the wireless network system, the access point (AP) and the station (STA) can be regarded as one basic service set. Therefore, the station STA can be regarded as a station (STA) for communicating with an access point (AP) in a range where all of the stations can communicate with the access point (AP). At this time, the station STA may be at least one station.

FIGS. 1 and 2 illustrate a process operating in the range of the entire channel bandwidth (0 to 160 MHz) with the passage of time. That is, it means that the time has elapsed along the horizontal axis, and the vertical axis can mean the range of each channel bandwidth.

1 is a diagram illustrating an embodiment of a wireless communication method according to the present invention.

1 shows AP-initiated coordination initiated by an access point (AP) and may represent a downlink / uplink (DL / UL) OFDMA scenario by an access point (AP).

Referring to FIG. 1, an embodiment of the present invention includes a first step in which an access point (AP) transmits an RTS signal (RTS * in FIG. 1) to a station (STA); A second step in which the station STA transmits a CTS signal (CTS * in Fig. 1) corresponding to the RTS signal (RTS * in Fig. 1); A third step of the access point AP transmitting the downlink data DL DATA in response to the CTS signal (CTS * in FIG. 1); A fourth step of the access point (AP) sending a trigger frame (Trigger * in FIG. 1) to the station (STA); (STA) transmits uplink transmission data (UL DATA) to the access point (AP); .

The access point AP may allocate a channel for transmitting the uplink data corresponding to the CTS signal (CTS * in FIG. 1), and receive the uplink data from the allocated channel using the trigger frame.

The access point AP allocates a channel for transmitting uplink data (UL DATA) corresponding to the CTS signal (CTS * in FIG. 1), and allocates a channel through the allocated channel using a trigger frame (Trigger * in FIG. 1) And receives the uplink transmission data UL from the stations STA1 to STA3.

In FIG. 1, three different stations STA 1 through STA 3 form a basic service set together with an access point AP and three stations STA 1 through STA 3 transmit downlink data DL DATA (STA1 to STA3) transmits uplink transmission data (UL DATA) to the access point.

An embodiment according to FIG. 1 will be described below.

It may be started after waiting for a predetermined time when the access point AP is in the idle state before attempting to transmit downlink data DL DATA. Here, the DIFS (Distributed Inter Frame Space) period may be exemplified for a predetermined time.

Then, the access point (AP) occupies the channel through the back-off process.

In the first step, an access point (AP) can transmit an RTS signal (RTS * in FIG. 1) to a station (STA). Here, the RTS signal (RTS * in FIG. 1) can use the same format as the RTS (Request to Send) signal used in the wireless communication method according to the conventional OFDMA scheme, but the corresponding RTS signal Can be further defined to indicate that the RTS of the CTS signal (CTS * of FIG. 1) is an RTS signal for requesting the CTS signal (CTS * of FIG. 1) to be performed.

The RTS signal (RTS * in FIG. 1) may be transmitted to all stations in the basic service set through all channels available according to the OFDMA scheme. In FIG. 1, the total channel bandwidth is 160 Mhz, and each channel can be divided into 8 channels in units of 20 Mhz.

In the second step, a CTS signal (see FIG. 1) indicating that the station, which has received the RTS signal (RTS * in FIG. 1) from the AP, is ready to receive downlink data (DL DATA) CTS *) to the access point (AP).

At this time, the CTS signal (CTS * in FIG. 1) is transmitted through a subchannel existing in each channel. When subchannels are initially connected to each other in the basic service set range of the AP, And each station can use different sub-channels even within the same channel.

The CTS signal (CTS * in FIG. 1) further includes a CTS (Clear to Send) signal used in a wireless communication method according to the conventional OFDMA scheme, in addition to which a station tries to transmit uplink data (UL DATA) Lt; / RTI > That is, the CTS signal (CTS * in FIG. 1) includes a transmission request of the stations STA 1 to STA 3 that desire the uplink data, which is the conventional RTS signal for the uplink transmission data (UL DATA) Can be understood to include the CTS signal of the present invention (CTS * in FIG. 1) as well.

More specifically, since the CTS signal (CTS * in FIG. 1) is transmitted to the AP through the subchannels assigned to each station, the access point AP transmits the CTS signal CTS *), it can be seen that the station allocated to the corresponding subchannel is ready to receive downlink data (DL DATA). In addition, the size of the uplink transmission data (UL DATA) to be transmitted by the station that has transmitted the corresponding CTS signal (CTS * in FIG. 1) to the CTS signal (CTS * May be included.

At this time, each of the stations STA 1 to STA 3 transmits a CTS signal (CTS * in FIG. 1) to all of the channels within the available channel bandwidth range to the AP. Referring to FIG. 1, since the STA 1 can use a channel within a range of 0 to 160 MHz, each of eight channels separated by 20 Mhz is divided into subchannels allocated to the STA 1 CTS signal (CTS * 1 in Fig. 1). Since the STA 2 can use the channel within the range of 120 to 160 MHz, the STA 2 can transmit the CTS signal (shown in FIG. 1) through the subchannel allocated to the station STA 2 to each of the two channels, CTS * 2). Since the station STA 3 can use the channel within the range of 80 to 160 MHz, the CTS signal (CTS in FIG. 1) is transmitted through the subchannels allocated to the station STA 3 to each of the four channels separated by 20 Mhz * 3). The above description is merely an example, and the size of the entire channel bandwidth or the channel bandwidth available for each station may be different, and the range of the bandwidth of one channel may also vary depending on the wireless communication environment.

The access point AP receives the CTS signal (CTS * 1 in FIG. 1) in the range of 0 to 160 Mhz and the CTS signal (CTS * 2) in the range of 120 to 160 Mhz, and in the range of 80 to 160 MHz CTS signal (CTS * 3). Therefore, the access point is ready to receive the downlink data (DL DATA) from the stations (STA1 to STA3) through the received CTS signal (CTS * 1 to 3 in FIG. 1) 3) wishes to transmit the uplink data (UL DATA). In addition, the access point AP can allocate a channel for receiving the UL data through the frequency range of each CTS signal (CTS * 1 to CTS 3 in FIG. 1).

In the third step, the access point AP transmits downlink transmission data (DL DATA) to the stations STA1 to STA3. Such downlink data can be transmitted to each station (STA1 to STA3) simultaneously through one or more channels available according to the OFDMA scheme.

At this time, the access point AP controls the data length of the downlink data DL DATA to be constant, so that a uniform amount of downlink data DL DATA is transmitted to all channels used for downlink transmission as much as possible, Can be increased.

After the access point AP has transmitted all of the downlink data DL DATA, each station STA 1 to STA 3, which has received the downlink data DL DATA, receives the downlink data DL DATA correctly (ACK) to inform the access point (AP).

In the fourth step, the access point AP transmits a trigger frame (Trigger * in Fig. 1) to the stations STA1 to STA3. In this case, the trigger frame (Trigger * in FIG. 1) includes, after the second step, information on a channel to which the AP allocates to the stations STA1 to STA3 and an access point DATA) is ready to be transmitted.

The access point AP transmits the uplink data UL DATA to the stations STA 1 to STA 3 to transmit the uplink data UL DATA in accordance with the uplink information of the stations STA 1 to STA 3, And allocates a channel for transmission. 1, an access point AP allocates four channels to a station STA 1 within a channel bandwidth range of 0 to 80 MHz, and allocates channels STA 1 to a station STA 2 within a channel bandwidth range of 140 to 160 MHz. And allocates three channels to the station STA 3 within a channel bandwidth range of 80 to 140 MHz. Here, FIG. 1 is merely an example, and the number of channels allocated to each other within the range of the channel bandwidth that each station can use may vary depending on the size of the UL DATA of each station.

In the fifth step, each of the stations (STA1 to STA3) can transmit the uplink data (UL DATA) to the access point through the channel allocated from the access point (AP). When all the uplink data (UL DATA) is received, the access point (AP) can transmit to the stations (STA 1 to 3) an acknowledgment signal (ACK in FIG.

2 is a view showing another embodiment of the present invention.

FIG. 2 shows station-initiated coordination initiated by a station, not an access point (AP), unlike FIG. 1, and may represent an uplink (UL) OFDMA scenario by a station.

Referring to FIG. 2, another embodiment of the present invention is a wireless communication method using orthogonal frequency division multiple access (OFDMA), in which a station that wishes to uplink data (UL) A first step of transmitting an RTS signal (RTS * in Fig. 2) through a first channel; The access point AP transmits the CTS signal (CTS * in FIG. 2) to the station through the first channel corresponding to the RTS signal (RTS * in FIG. 2) and transmits the trigger frame (Trigger * ) To the station; A station up-transmitting (UL) data to an access point (AP) through the first and second channels; .

FIG. 2 illustrates a case where one station included in a basic service set of an access point (AP) has data to be up-transmitted (UL) to an access point (AP).

The embodiment according to FIG. 2 will be described below.

Before the station transmits the uplink transmission data (DATA in FIG. 2), if the channel state is idle, it can be started after waiting for a certain period of time. Here, the DIFS (Distributed Inter Frame Space) period may be exemplified for a predetermined time.

Thereafter, the station occupies the channel through a back-off process.

In the first step, a station desiring to uplink (UL) data (DATA in FIG. 2) can transmit an RTS signal (RTS * in FIG. 2) over a first channel available to the station to an access point .

Here, the first channel available to the station means a channel available to the station in the OFDMA scheme. The first channel can have various available channels according to the wireless communication environment. In FIG. 2, the station has a bandwidth of 0 to 40 MHz The channel availability is illustrated in FIG.

In FIG. 2, it is illustrated that the size of one channel is 20 Mhz, so that the station can have two available channels in the channel range of 0 to 40 Mhz. Therefore, the station transmits an RTS signal (RTS * in FIG. 2) to the access point through two channels.

Here, the RTS signal (RTS * in FIG. 2) may use the same format as the RTS (Request to Send) signal used in the wireless communication method according to the conventional OFDMA scheme, Can be further defined to indicate that the RTS signal is an RTS signal for requesting a CTS signal (CTS * in FIG. 2) to be performed.

In a second step, the access point AP transmits an RTS signal (RTS * in FIG. 2) corresponding to the RTS signal (RTS * in FIG. 2) 2 CTS *) to the station and a trigger frame (Trigger * in FIG. 2) to the station via the second channel.

Here, the second channel may denote a channel other than the first channel among all the channels that the access point (AP) can use to downlink (DL) to the station, and the second channel may be a channel other than the first channel Or some of the available channels. In FIG. 2, a bandwidth range of 0 to 40 Mhz is referred to as a first channel, and a bandwidth range of 40 to 160 Mhz is illustrated as a second channel.

The trigger frame (Trigger * in FIG. 2) is a frame for transmitting from the access point AP to the station, and can have the same structure as the CTS signal (CTS * in FIG. 2) Allows the transmission of the trigger frame (Trigger * in FIG. 2) to end at the same time as the transmission of the CTS signal (CTS * in FIG. 2). In FIG. 2, the range of the second channel is exemplified in the range of 40 to 160 Mhz, and the trigger frame (Trigger * in FIG. 2) is transmitted through the six channels of the range.

The access point AP may assign the first and second channels to the uplink (UL) of the station by transmitting a trigger frame (Trigger * in Figure 2) over the second channel in addition to the station's first available channel .

In the third step, the station transmits uplink (AP) data (DATA in FIG. 2) upwards through the first and second channels allocated from the AP. When the access point AP receives all of the uplink data (DATA in FIG. 2), it can transmit an acknowledgment signal (ACK in FIG. 2) to the station indicating that it has been correctly received.

As described above, according to another embodiment of the present invention as shown in FIG. 2, when a station transmits data upwards, it transmits upwards by using up to a channel other than an available channel (first channel) The channel is used as much as possible and the transmission speed is improved.

Claims (16)

delete delete delete delete delete delete delete delete delete delete A method of wireless communication using orthogonal frequency division multiple access (OFDMA)
A first step of transmitting a RTS signal to an access point through a first channel available to the station;
A second step of the access point transmitting a CTS signal to the station on the first channel corresponding to the RTS signal and transmitting a trigger frame to the station on a second channel not overlapping the first channel;
A third step in which the station transmits the data up to the access point via the first and second channels; Lt; / RTI > 12. The method of claim 11, wherein the RTS signal is
Wherein the station is transmitted within a range of usable channels. 12. The apparatus of claim 11, wherein the first and second channels
Wherein the access point or the station is a channel within a range of usable channel bandwidth. 12. The method of claim 11, wherein the trigger frame
Wherein the CTS signal has the same size as the CTS signal. 12. The method of claim 11,
Transmitting an acknowledgment signal indicating that the access point has received the data to the station after the station has transmitted the data upward; Further comprising the steps of: 12. The method of claim 11,
Wherein the access point transmits the CTS signal and the trigger frame via at least one of the one or more first channels and one or more second channels,
Wherein the station transmits the RTS signal and the uplink data via at least one of the first channel and the at least one second channel.

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