KR20120081040A - Method and apparatus for transmitting symbol repeatedly in wireless communication system - Google Patents

Abstract

PURPOSE: A method and apparatus for repeatedly transmitting a symbol in a wireless communication system are provided to maintain compatibility with a conventional wireless telecommunication system by transmitting a frame with symbol repetition. CONSTITUTION: A transmitter generates a first signal field(S1100). The first signal field is an L-SIG(Legacy Signal) field. A second signal field is formed by reiterating a symbol of the first signal field(S1105). A second signal field is an N-SIG(New Signal) field. The second signal field is formed into a structure of including repeated symbols through a modulation method. A frame including the first signal field, the second signal field, and a data field is transmitted(S1110).

Description

METHOD AND APPARATUS FOR TRANSMITTING SYMBOL REPEATEDLY IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for repeatedly transmitting a symbol.

In a wireless communication system, active researches are being conducted to provide users with various quality of service (QoS) services having high transmission speeds. As an example of such a communication system, in a wireless local area network (WLAN) system, studies are being actively conducted on methods for transmitting a large amount of data at high speed and stably through limited resources. In particular, researches on data transmission through a wireless channel have been conducted in a wireless communication system. Recently, methods for efficiently transmitting and receiving a large amount of data using a limited wireless channel have been proposed.

In addition, wireless communication systems use higher order modulation methods, more carriers in limited frequency bands, and reduced symbol lengths to improve data rate and throughput. By performing symbol repetition, a diversity effect can be obtained and the service area can be enlarged. As the number of symbol repetitions increases, the signal reach distance increases, while the data transmission rate decreases. In other words, the signal reach and the data transmission rate are in a trade off relationship.

Meanwhile, in a communication system, a large amount of data transmitted and received through a wireless channel, such as a data packet, includes a data field including data transmitted and received through the wireless channel, and a signal field including information about the data field. signal field), and the communication system normally checks whether the signal field is normal, and then normally transmits and receives data included in the data field according to whether the signal field is normal.

However, since the transmission power of the wireless communication system is limited due to frequency regulation, the system design conditions have a limitation in that the reach of the signal is limited while improving the data transmission speed, and thus it is required to improve the transmission power.

An object of the present invention is to expand the service area while maintaining compatibility with a conventional wireless transmission device.

Another technical problem of the present invention is to transmit the number of repeated symbols while repeatedly transmitting a symbol.

Another technical problem of the present invention is to improve signal reach with diversity gain.

According to an aspect of the present invention, a method of transmitting data by a transmitter in a wireless communication system includes generating a first signal field, generating a second signal field configured by repeating a symbol of the first signal field; And transmitting a frame including the first signal field, the second signal field, and the data field.

The first symbol of the second signal field may be modulated with binary phase shift keying (BPSK), and the symbols after the second symbol of the second signal field may be modulated with Q-BPSK.

The first symbol of the second signal field may be modulated with BPSK, and the symbols after the second second symbol may be modulated with Q-BPSK or Spread-QPSK (S-QPSK).

At least the first three symbols of the second signal field may be BPSK modulated.

The second signal field may consist of one BPSK modulated symbol.

The second signal field may be configured by being modulated with at least one symbol that is S-QPSK modulated.

The method may further include generating a third signal field configured by repeating the symbol of the first signal field, and the frame may further include the third signal field.

The frame may further include a preamble, and the preamble may include one of a short preamble and a long preamble, or may include both the short preamble and the long preamble.

The frame may be a legacy frame of the 802.11a / g standard.

The frame may be a high throughput (HT) frame of the 802.11n standard.

The frame may be a Very High Throughput (VHT) frame of the 802.11ac standard.

Rate information of the second signal field may include a transmission rate of the data field.

The number of symbol repetitions of the second signal field may be determined according to a modulo 3 operation of frame length information of the first signal field.

The symbol repetition number may be a time domain repetition number or a frequency domain repetition number.

The bandwidth mode of the second signal field may be determined according to a result of modulo operation of the frame length information of the first signal field.

The modulation method of the symbol of the data field may be determined according to a result of performing a modulo operation on the frame length information of the first signal field.

The CCA busy time, which is the time at which the receiving end of the frame recognizes that the channel is not in an idle state, may be determined according to the length information of the first signal field.

The repetition of the symbols of the first signal field may be a time domain repetition method of transmitting the same information after one symbol but repeatedly transmitting the rearranged symbols in a specific pattern.

The repetition of the symbols of the first signal field may use a frequency domain repetition method in which signals transmitted in one bandwidth are rearranged in a specific pattern using another adjacent bandwidth or repeatedly transmitted in the same signal.

According to another aspect of the present invention, a transmitting apparatus for transmitting data in a wireless communication system generates a first signal field, generates a second signal field configured by repeating a symbol of the first signal field, and generates the first signal field. And a processor for transmitting a frame comprising a signal field, the second signal field, and a data field.

According to the configuration of the present invention, by transmitting the frame using the symbol repetition it is possible to extend the area of service while maintaining compatibility with the conventional wireless communication system.

1 is a diagram illustrating frame formats to which the present invention is applied.
2 illustrates a signal field format of a legacy frame to which the present invention is applied.
3 shows a signal field format of an HT frame.
4 illustrates an example of a radio transmission legacy frame configured using a symbol repetition scheme according to the present invention.
5 shows an example of a radio transmission HT frame (or VHT frame) configured using a symbol repetition scheme according to the present invention.
6 and 7 show another example of a frame according to the present invention.
8 illustrates an example of applying dynamic bandwidth allocation as an embodiment of the symbol repetitive transmission method described above.
9 illustrates an example of applying a duplicate mode as an embodiment of the symbol repetitive transmission method described above.
10 shows an example of a pattern for performing symbol repetitive transmission according to the present invention.
11 is an example of a flowchart illustrating a method of transmitting data by a transmitter according to the present invention.
12 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention is implemented.

With regard to the WLAN standard, after 802.11a / g with 54Mbps transmission rate is used, the 802.11n standard with up to 600Mbps transmission rate is created, and then the 802.11ac standard is created to support higher throughput. .

The frame of the data packet includes a data field DATA for data transmission and a signal field SIG for information transmission on the data field. The frame of the data packet includes a data field and a signal field and a training field for transmitting a preamble for the frame. By transmitting and receiving a frame of the generated data packet, a large amount of data can be transmitted and received through limited resources.

1 is a diagram illustrating frame formats to which the present invention is applied.

Referring to FIG. 1, (a) is used in the 802.11a / g standard as a legacy frame (or legacy mode frame). (b) is used in the 802.11n standard as a High Throughput (HT) frame (or HT mode frame). (c) is used in the 802.11ac standard as a Very High Throughput (VHT) frame (or VHT mode frame).

The legacy frame includes a legacy preamble (short preamble (L-STF) and long preamble (L-LTF)), legacy signal field (L-SIG), and data field (DATA).

In order to maintain compatibility with 802.11a / g for the 802.11n standard, the HT frame includes legacy preambles (L-STF and L-LTF), legacy signal fields, and data fields. In addition, the legacy terminals set the rate to 6Mbps to prevent channel access when receiving the HT frame, and transmits the time that the HT frame occupies the channel in packet length information. At the same time, the HT signal field (HT-SIG) modulated by Q-Binary Phase Shift Keying (Q-BPSK) is included in the HT frame to allow the HT UEs to distinguish between the legacy frame and the HT frame, and the HT preamble (HT- STF and HT-LTF) are further included.

In the case of the VHT frame of the 802.11ac standard, the first symbol of the VHT-SIG1 is maintained as the BPSK, and the second symbol is modulated by the Q-BPSK to transmit the legacy frame, the HT frame, and the VHT frame. Unlike the HT frame, the VHT frame includes the VHT-SIG1 and VHT-SIG2 signal fields separated from each other.

2 illustrates a signal field format of a legacy frame to which the present invention is applied.

Referring to FIG. 2, the signal field may include a rate bit (eg, 4 bits) and a packet length bit (eg, 10 bits) of the data field. In addition, the signal field further includes a 1-bit reserved (R) bit, a 1-bit parity check (P) and a tail (tale) bit (eg, 6 bits).

3 shows a signal field format of an HT frame. (a) is the HT-SIG ₁ field, and (b) is the HT-SIG ₂ field.

Referring to FIG. 3, the HT-SIG ₁ field includes a modulation and coding scheme (MCS), CBW 20/40 bits, and HT Length bits. The HT-SIG ₂ field includes smoothing, not sounding, reserved bits, two bits of Space Time Block Coding (STBC) bits, Forward Error Correction (FEC) coding bits, SHORT GI, extended Number of extension spatial streams, a Cyclic Redundancy Check (CRC) code, and tail bits.

Now, a frame transmission method according to the present invention will be described.

The frame format according to the present invention further includes a signal field (N-SIG) newly defined as well as a signal field (L-SIG) used in wireless terminals. The preamble included in the frame may include both a short preamble (L-STF) and a long preamble (L-LTF).

4 illustrates an example of a radio transmission legacy frame configured using a symbol repetition scheme according to the present invention.

Referring to FIG. 4 (mode 1), a legacy preamble and a signal field L-SIG field are included to maintain compatibility with other wireless transmission schemes. In addition, the N-SIG field is further included after the L-SIG field.

The N-SIG field is configured to be modulated through a BPSK modulation scheme or a Spread Quadrature Phase Shift Keying (S-QPSK) modulation scheme. Embodiments of configuring the N-SIG field according to the present invention are as follows.

As an example (Embodiment 1), the N-SIG field is configured by repeatedly using the symbols of the L-SIG field, but the first symbol of the N-SIG field is modulated by BPSK, and Q after the second symbol of the N-SIG field. Configure to be modulated by BPSK. Q-BPSK is a modulation method in which the BPSK is phase shifted by 90 degrees. When the frame including the N-SIG field is transmitted to the receiving end, the receiving end may determine whether the symbol of the L-SIG field is repeated in the frame based on whether or not a symbol modulated by the BPSK exists. In addition, the receiver may determine the number of symbol repetitions based on the number of Q-BPSK symbols before the first symbol of the N-SIG field. In addition, the N-SIG field may include rate and length information of a symbol repetitive transmission frame, and bandwidth mode information may be transmitted through a result of performing "modulo 3" operation on the frame length information included in the N-SIG field. have. Here, since BPSK and Q-BPSK have the longest Euclidean distance, a comparative detection method of BPSK and Q-BPSK was used, but it is also possible to compare other modulation schemes. For example, comparing BPSK and S-QPSK. Application of detection is also possible.

As another example (Embodiment 2), the N-SIG field is configured by using symbols of the L-SIG field repeatedly, wherein the first symbol of the N-SIG field is modulated by BPSK, and Q after the second symbol of the N-SIG field. Configure to be modulated with BPSK or S-QPSK. In this case, the first consecutive three BPSK modulated symbols of the N-SIG field can be distinguished from other terminals (802.11a / g, 802.11n, 802.11ac), the fourth symbol of the N-SIG field is BPSK modulated Not a symbol can be used to determine a new frame. In addition, by repeating the first symbol of the L-SIG field in the N-SIG field, it is possible to enable spoofing to enable service area extension to the terminal supporting symbol repetitive transmission, and the N-SIG field The including frame may be distinguished from an 802.11n HT frame. In addition, a frame including the N-SIG field may be distinguished from an 802.11ac VHT frame in that the first symbol of the N-SIG field is a BPSK modulated symbol. A frame including the N-SIG field may be distinguished from an existing frame in that the second symbol of the N-SIG field is a Q-BPSK or S-QPSK modulated symbol. In this case, since the UE supporting symbol repetitive transmission knows the modulation pattern of the first symbol and the second symbol of the N-SIG field in advance, a diversity gain can be obtained by using the two symbols together.

As another example (embodiment 3), the N-SIG field may be configured to further repeat a plurality of BPSK modulated symbols. That is, the N-SIG field is configured such that at least the first three symbols of the N-SIG field are all BPSK modulated. Therefore, even if other terminals (802.11a / g, 802.11n, 802.11ac) receives the frame including the N-SIG field is determined as a legacy frame, spoofed by the rate information and frame length information of the first L-SIG field It can be done. On the other hand, terminals capable of extending the service area by symbol repetition are received when the rate information of the L-SIG field is set to 9 Mbps or the result of calculating the modulo 3 of the frame length information is not 0 (1 or 2). One frame is determined to be a frame including an N-SIG field.

As another example (Embodiment 4), the N-SIG field may consist of one BPSK modulated symbol. At this time, the 802.11n terminal is not a problem by judging the legacy mode frame by the consecutive BPSK symbols, but in the case of 802.11ac terminal may not be a problem since the BPSK modulation method after the N-SIG field. Therefore, the rate information of the L-SIG field may be set to 9Mbps so that another terminal recognizes the frame as a legacy frame, and the rate information of the N-SIG field may be configured to include the transmission rate of the data field.

As another example (embodiment 5), the N-SIG field may be configured such that at least one symbol is S-QPSK modulated and repeated in addition to the BPSK modulated symbol. In this case, in order for the frame including the N-SIG field to be recognized as a legacy frame by the terminals (802.11a / g terminal, 802.11n terminal or 802.11ac terminal), the rate information of the L-SIG field is set to 9Mbps, Rate information of the N-SIG field may be set to include the transmission rate of the data field. That is, the rate information of the first symbol of the N-SIG field is set to 9Mbps, the BPSK modulation, the transmission time is set in the length information, and includes the rate information used for data field modulation from the second symbol of the N-SIG field. S-QPSK is modulated and repeatedly transmitted a predetermined number of times.

In the case of the WLAN device receiving the frame, the 802.11a / g receiving end receives 9Mbps and the spoofing of the L-SIG field is possible according to the length information, and since the 802.11n receiving end or the 802.11ac receiving end is not a 6Mbps mode packet, legacy Spoofing of the L-SIG field is possible by judging by the frame.

In addition, the frequency diversity effect can be obtained through the S-QPSK modulated symbols, thereby extending the signal reach distance, and the frame is applied to the symbol repetition technique according to the present invention by detecting the S-QPSK modulation at the receiving end. You can see that it is a frame.

5 shows an example of a radio transmission HT frame (or VHT frame) configured using a symbol repetition scheme according to the present invention.

Referring to FIG. 5 (mode 2), (a) includes a legacy preamble and an L-SIG field to maintain compatibility with a conventional terminal, includes an N-SIG field according to the present invention, and another N. It further includes an N-SIG 'field which is a -SIG field. It may also include an N-preamble field and an N-data field.

The N-SIG field may be configured through the first to fifth embodiments of FIG. 4 described above. The N-SIG 'field is configured to repeatedly transmit the symbols of the L-SIG field through Q-BPSK or S-QPSK modulation.

At this time, the receiving end may detect the start of the N-SIG 'field through the transmission point of the Q-BPSK or S-QPSK modulated symbol. The embodiment of FIG. 4 and the embodiment of FIG. 5 can be distinguished by the presence or absence of the N-SIG 'field. Therefore, the number of symbol repetitions can be distinguished by the presence or absence of the N-SIG 'field. That is, the number of symbol repetitions can be known from the number of symbols in the N-SIG field until the N-SIG 'field starts.

5 (b) includes a legacy preamble and L-SIG field in order to maintain compatibility with the conventional terminal, it can be distinguished from 802.11a / g, 802.11n, 802.11ac and the frame (a) of FIG. New signal field N-SIG ''.

As another example, the N-SIG '' field may be configured by adding the N-SIG field and the N-SIG field '.

If the N-SIG field or the N-SIG 'field (or N-SIG' 'field) is transmitted with information related to the number of time-domain repetitions or frequency-domain repetitions, the receiver may perform decoding using the information. .

5 (c) shows another example of a frame to which the present invention is applied in the WLAN standard. The frame may be an HT frame and may further include an HT-N-SIG field, which is a new signal field, and an HT-N-LTF field, which is a new preamble field.

Meanwhile, a method of informing a modulation method of a data symbol using rate information (L-RATE) in order to maintain compatibility of a frame to which the symbol repetition technique is applied and to extend the reach distance in the frame transmission method using the symbol repetition technique will be described.

For example, when the rake information is 9Mbps, the data symbols may be preset to be modulated by S-QPSK and transmitted using a symbol repetition technique.

As shown in Equation 1, it is possible to define to set the packet length value of the L-SIG field (see section 9.13.4 of the IEEE 802.11n WLAN standard).

Substituting the parameter values defined in the IEEE 802.11n WLAN standard can be simplified as shown in Equation 2 below.

Equation 2 may be changed as follows to determine the number of time domain repetitions or the number of frequency domain repetitions.

Here, n is a value of one of 0, 1, or 2, and indicates the number of time domain repetitions or the number of frequency domain repetitions. For example, it may be set to repeat one time when n is 0, repeat twice when n is 1, and repeat four times when n is 2. In addition, when the time domain repetition technique is used, the same symbol may be repeatedly transmitted 2 ^n-1 times. Similarly, when the frequency domain repetition technique is used, the same band is duplicated and transmitted 2 ^n-1 times. You can do that.

For example, since Equation 3 is obtained by subtracting n from a multiple of 3, the number of symbol repetitions (time domain repetition count or frequency domain repetition count) is determined according to the result of modulo 3 calculating the frame length information of the signal field. Can be sent. For example, if the result of calculating the frame length information of the signal field by modulo 3 is 0, repeats it once, and if the result of calculating the modular length of the signal field by modulo 3 is 1, repeats twice, and the signal If the frame length information of the field 3 is modulo 3, the value is repeated three times. At this time, if the result of performing the modulo 3 operation on the frame length information of the signal field is 2, the data symbol is repeated three more times, thereby increasing the signal reach while reducing the transmission speed by 1/4 times. In addition, the signal field may be an L-SIG field or an N-SIG field.

As another example, the bandwidth mode may be determined and transmitted according to a result of performing the modulo 3 operation on the frame length information of the signal field. For example, 5 MHz bandwidth repetition mode (bandwidth mode 1) when the result of calculating the frame length information of the signal field by module 3 is 0, and 10 MHz bandwidth when the result of calculating the frame length information of the signal field by module 3 is 1 In the repetition mode (bandwidth mode 2), if the result of modulo 3 calculating the frame length information of the signal field is 2, the repetition mode (bandwidth mode 3) is set. That is, assuming that the wireless transmission system is a 20MHz mode, when the result of calculating the modulo 3 of the frame length information of the signal field is 1, the 10MHz bandwidth signal from the data field symbol is repeated twice in the frequency domain and 20MHz Transmitted in bandwidth. In this case, the signal field may be an L-SIG field or an N-SIG field.

As another example, a modulation method of a data symbol may be determined and transmitted based on a result of modulo 3 calculating the frame length information of the signal field. For example, when the frame length information of the two signal symbols is modulo 3, if it is not 0 (1 or 2), the data symbol may be modulated by S-QPSK and symbol repeated transmission.

Meanwhile, the CCA busy time may be obtained using the length information of Equation 2 as shown in the following equation. Here, the CCA busy time refers to the time when the receiver recognizes that the channel does not idle.

For example, in the case of a radio transmission method in which one symbol duration is longer than 4 us (4 * N) us (where N is an integer), Equation 4 may be changed as in the following equation.

In this case, the IFS (Interframe space) is also increased by N times, making it difficult to acquire channel occupancy rights in a competition-based protocol such as CSMA / CA. Accordingly, the terminal that increases the symbol duration N times in a modified form as shown in the following equation may calculate the CCA busy time.

At this time, the CCA busy time of the data packet transmitted by Equation 3 is as follows.

6 and 7 show another example of a frame according to the present invention.

Referring to FIG. 6, the frame represents one symbol repeating frame of the legacy frame. 6 includes a short preamble (L-STF) and a long preamble (L-LTF), which are preambles for legacy compatibility, and include a legacy signal field (L-SIG). As an example, the symbols of the L-SIG field are modulated with BPSK.

In the L-STF, carrier sensing and automatic gain adjustment are performed, and carrier frequency error can be estimated. In the L-LTF, fine carrier frequency error may be estimated, symbol synchronization may be performed, and channel estimation may be performed. The L-SIG field includes frame information such as rate and frame length. A terminal that does not use the symbol repetition technique may spoof by setting a network allocation vector (NAV) based on the frame information. In addition, the L-SIG field may include information indicating the number of frequency domain repetitions or the number of time domain symbol repetitions.

6, the symbol 620 repeats the symbols of the L-SIG field of 610, and is modulated by Q-BPSK. Accordingly, the terminal supporting the symbol repetition technique may know whether the received frame is in symbol repetition mode or not based on Q-BPSK modulation. Diversity gain can be obtained through symbol repetition, thereby improving reception performance of the terminal.

6 is a new field (N-SIG) for symbol repetitive transmission, and includes information such as a frame rate and a length of a symbol repetitive transmission frame. For example, '630' is BPSK modulated, and the receiver may count the number of symbol repetitions by counting the number of repeated Q-BPSK symbols.

6 is a field in which symbols of the N-SIG field are repeated, and the symbols may be transmitted after being Q-BPSK modulated or BPSK modulated. According to whether the symbols of '640' are Q-BPSK modulated or BPSK modulated, additional information such as whether the frequency is duplicated may be indicated.

In FIG. 6, '650' is a data field, and the OFDM symbol is repeatedly transmitted. The terminal supporting the symbol repetition technique may restore the data symbols according to the number of symbol repetitions found in the signal field and its mode.

Referring to FIG. 7, a frame represents a two symbol repeating frame of a legacy frame.

Referring to FIG. 7, symbols of an L-SIG field of '710' are repeated twice by being Q-BPSK modulated at '720', and symbols of an N-SIG field of '730' are BPSK or Q- at '740'. BPSK modulated and repeated twice.

The receiver may recognize that the number of repetitions is 2 by detecting the Q-BPSK modulated symbol repeated before the N-SIG field.

On the other hand, the comparative detection of the BPSK and Q-BPSK in the present invention is an example of using the assumption that the Euclidean distance between the BPSK and Q-BPSK is far away, and uses a different modulation scheme (for example, S-QPSK) Embodiments are also possible.

8 illustrates an example of applying dynamic bandwidth allocation as an embodiment of the symbol repetitive transmission method described above.

Referring to FIG. 8, it is assumed that bandwidth (BandWidth: BW) mode 0 is 20 MHz, bandwidth mode 1 is 10 MHz, and bandwidth mode 2 is 5 MHz. In this case, bandwidth information may be designated as a modulo 3 result of the frame length information of the present invention when transmitting a Request to Send (RTS) and a Clear to Send (CTS).

If the terminal transmits the RTS signal in bandwidth mode 0 through the channel 1 to the channel 4 before transmitting the data frame, the RTS receiving terminal detects the interference on the channel 1 and the channel 2 and transmits the CTS only on the channel 3 and the channel 4 By setting the bandwidth to narrower bandwidth (bandwidth mode 1), the data can be sent to channel 3 and channel 4. An acknowledgment (ACK) signal can also be transmitted in the same manner as data.

9 illustrates an example of applying a duplicate mode as an embodiment of the symbol repetitive transmission method described above.

Referring to FIG. 9, it is assumed that bandwidth mode 0 is 20 MHz, bandwidth mode 1 is 10 MHz, and bandwidth mode 2 is 5 MHz. In this case, duplicate information may be designated as a modulo 3 result of frame length information of the present invention during RTS and CTS transmission.

When the terminal transmits the RTS signal to the channel 1 to channel 4 before the data frame transmission, the RTS receiving terminal detects the interference of the channel 1 and channel 2, and transmits the CTS only in the channel 3 and channel 4 with a narrower bandwidth to the CTS If set, data and ACK can be transmitted on channel 3 and channel 4.

In this case, since the RTS and the CTS are each set to the bandwidth mode 3 (5 MHz) which is the narrowest bandwidth, the UE may repeatedly transmit the same symbol to the channel 3 and the channel 4 in the duplicate mode, thereby obtaining frequency diversity. The service area can be further expanded.

The symbol repetition transmission method used in the present invention includes a time domain repetition method and a frequency domain repetition method. The time-domain iterative transmission method is a transmission method in which the same information as a symbol is transmitted after one symbol, but the symbol reordered in a specific pattern is repeatedly transmitted to obtain a diversity effect. The frequency domain repetitive transmission method is a transmission method in which a signal having one bandwidth is rearranged in a specific pattern using another adjacent band or repeatedly transmitting the same signal to obtain diversity effect.

The pattern for symbol repetitive transmission may vary depending on implementation.

10 shows an example of a pattern for performing symbol repetitive transmission according to the present invention.

Referring to FIG. 10, the carrier of the negative index of the first OFDM symbol modulation sequence is transmitted with the positive index of the second OFDM symbol modulation sequence, and the carrier of the positive index of the first OFDM symbol modulation sequence is the second OFDM symbol. It can be transmitted on the carrier of the negative index of the modulation sequence. Fast Fourier operation is easy.

11 is an example of a flowchart illustrating a method of transmitting data by a transmitter according to the present invention.

Referring to FIG. 11, the transmitter generates a first signal field (S1100). The first signal field is an L-SIG field.

A second signal field configured by repeating the symbol of the first signal field is generated (S1105). The second signal field is an N-SIG field. The second signal field is configured to repeat the symbol through the modulation method of the first to fifth embodiments.

The frame including the first signal field, the second signal field and the data field is transmitted (S1110).

12 is a block diagram illustrating a wireless communication system in which an embodiment of the present invention is implemented.

The transmitter 1200 includes a processor 1210, a memory 1220, and an RF unit 1230.

The processor 1210 may be connected to the memory 1220 and the RF unit 1230 to control them. The processor 1210 generates a second signal field so that the symbol of the first signal field is repeated according to the present invention, and generates a frame including the first signal field and the second signal field.

The memory 1220 is connected to the processor 1210 and stores various information for driving the processor 1210.

The RF unit 1230 is connected to the processor 1210 and transmits and / or receives a radio signal. The frame generated by the processor 1210 is transmitted to the receiving end.

The processor may comprise an application-specific integrated circuit (ASIC), other chipset, logic circuitry and / or a data processing device. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit may include a baseband circuit for processing a radio signal. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module is stored in memory and can be executed by the processor. The memory may be internal or external to the processor and may be coupled to the processor by any of a variety of well known means.

In the above-described exemplary system, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders or simultaneously . It will also be understood by those skilled in the art that the steps shown in the flowchart are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention.

Claims (20)

A method for transmitting data by a transmitter in a wireless communication system,
Generating a first signal field comprising at least one symbol;
Generating a second signal field configured by repeating at least one symbol of the first signal field; And
Transmitting a frame comprising the first signal field, the second signal field and the data field. The method of claim 1,
And a first symbol of the second signal field is modulated with binary phase shift keying (BPSK) and a symbol after the second symbol of the second signal field is modulated with Q-BPSK. The method of claim 1,
A first symbol of the second signal field is modulated with BPSK, and a symbol after the second second symbol is modulated with Q-BPSK or Spread-QPSK (S-QPSK). The method of claim 1,
At least the first three symbols of the second signal field are BPSK modulated. The method of claim 1,
And the second signal field consists of one BPSK modulated symbol. The method of claim 1,
And wherein the second signal field is modulated with at least one symbol that is S-QPSK modulated. The method of claim 1,
Generating a third signal field configured by repeating the symbols of the first signal field;
The frame further comprises the third signal field. The method of claim 1,
The frame further includes a preamble,
The preamble includes one of a short preamble and a long preamble, or both the short preamble and the long preamble. The method of claim 1,
The frame is a data transmission method, characterized in that the legacy (legacy) frame of the 802.11a / g standard. The method of claim 1, wherein
The frame is a data transmission method, characterized in that the HT (High Throughput) frame of the 802.11n standard. The method of claim 1, wherein
The frame is a data transmission method, characterized in that the VHT (Very High Throughput) frame of the 802.11ac standard. The method of claim 1,
The rate information of the second signal field is set to include a transmission rate of the data field. The method of claim 1,
The number of symbol repetitions of the second signal field is determined according to a modulo 3 operation of the frame length information of the first signal field. The method of claim 13,
The symbol repetition number is
A data transmission method, characterized in that the number of time domain repetitions or frequency domain repetitions. The method of claim 1,
The bandwidth mode of the second signal field is determined according to a result of performing a three-module operation on the frame length information of the first signal field. The method of claim 1,
And a modulation method of a symbol of the data field is determined according to a result of modulo operation of frame length information of the first signal field. The method of claim 1,
And a CCA busy time, which is a time for recognizing that a channel is not in an idle state at the receiving end of the frame, is determined according to length information of the first signal field. The method of claim 1,
Repetition of the symbol of the first signal field,
A time domain repetition method of transmitting the same information after one symbol but repeatedly transmitting a rearranged symbol in a specific pattern. The method of claim 1,
Repetition of the symbol of the first signal field,
A data transmission method comprising a frequency domain repetition method of rearranging a signal transmitted in one bandwidth using a different adjacent bandwidth in a specific pattern or repeatedly transmitting the same signal. A transmitting device for transmitting data in a wireless communication system,
Create a first signal field,
Generate a second signal field configured by repeating the symbols of the first signal field,
And a processor for transmitting a frame including the first signal field, the second signal field, and the data field.

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