KR20150005476A

KR20150005476A - Method for transmitting signal in communcation system

Info

Publication number: KR20150005476A
Application number: KR1020140083666A
Authority: KR
Inventors: 장갑석; 곽병재; 이문식
Original assignee: 한국전자통신연구원
Priority date: 2013-07-05
Filing date: 2014-07-04
Publication date: 2015-01-14

Abstract

A signal transmission method in a communication system is disclosed. The signal transmission method includes generating an STF composed of one CP and four repeated pattern regions included in a valid symbol interval, generating an LTF composed of one CP and two repeated pattern regions included in the valid symbol interval , Generating a frame including STF and LTF, and transmitting the frame. Thus, the efficiency of the communication system can be improved.

Description

[0001] METHOD FOR TRANSMITTING SIGNAL IN COMMUNCATION SYSTEM [0002]

The present invention relates to a method of transmitting a signal in a wireless communication system.

In a wireless local area network (WLAN) system, a short training field (STF) can be used for auto gain control, packet estimation, initial time / frequency synchronization estimation, and the like. The transmitting terminal can generate a plurality of repeated pattern areas by assigning a complex sequence element for each subcarrier preset in the frequency band of the STF. The transmitting terminal may generate an orthogonal frequency division multiplexing (OFDM) symbol including a cyclic prefix (CP) and a plurality of repeated pattern regions. The transmitting terminal can generate a plurality of OFDM symbols through this process.

If the interval used for automatic gain control in the STF is set to a maximum of one OFDM symbol, the receiving terminal estimates the packet using the repeated pattern area included in the remaining OFDM symbols in the STF and estimates the initial time / frequency synchronization do. In this case, since the number of samples included in the repetitive pattern area is small, the signal to noise ratio (SNR) is lowered, thereby degrading the initial time / frequency synchronization performance.

On the other hand, the LTF (long training field) in the WLAN system can be used for detailed time / frequency synchronization estimation, channel estimation, and the like. The LTF is composed of the same number of OFDM symbols as the STF, and includes a CP having a size twice as large as the STF and two repeating pattern areas. There is a problem that resources are wasted because LTF includes more resources than necessary for fine time / frequency synchronization estimation and channel estimation.

On the other hand, in a wireless LAN system, a receiving terminal can not detect whether a current frame collides with a preamble of a received frame.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of transmitting a signal including a preamble designed to improve efficiency of a communication system.

According to an aspect of the present invention, there is provided a method for transmitting a signal, the method including generating a STF including one CP and four repeated pattern regions included in a valid symbol interval, Generating an LTF composed of two repetitive pattern areas included, generating a frame including the STF and the LTF, and transmitting the frame.

Here, the polarity of an arbitrary repetition pattern area among the four repetition pattern areas included in the effective symbol interval of the STF may be set differently according to the transmission mode of the frame.

Here, the polarity of the last repetitive pattern region among the four repetitive pattern regions included in the valid symbol period of the STF may be set to be opposite to the polarity of the previous repetitive pattern region to indicate the end of the STF.

Here, a sequence element may be allocated to odd-numbered or even-numbered subcarriers of each repeated pattern region included in the effective symbol interval of the STF.

Here, the base sequence element and the modified sequence element generated based on the base sequence element may be alternately allocated to the odd-numbered or even-numbered subcarriers.

Herein, a base sequence element is assigned to odd-numbered or even-numbered subcarriers included in an upper frequency band of each of the repetition pattern areas, and odd-numbered or even-numbered subcarriers included in a lower- Element may be assigned to the generated sequence element.

Here, the polarity of an arbitrary repetition pattern area among the two repetition pattern areas included in the valid symbol period of the LTF may be set differently according to the transmission mode of the frame.

Herein, a base sequence element is allocated to odd subcarriers of each repetition pattern area included in the LTF effective symbol interval, and the base sequence element is allocated to even subcarriers among the repeated pattern areas included in the LTF effective symbol interval. May be assigned to the generated sequence element.

Herein, a base sequence element is allocated to a sub-carrier included in an upper frequency band of each repetition pattern area included in an effective symbol interval of the LTF, and a base sequence element is included in a lower frequency band of each repetition pattern area included in the effective symbol interval of the LTF. And the transformed sequence elements generated based on the base sequence elements may be assigned to the subcarriers.

According to another aspect of the present invention, there is provided a method for transmitting a signal, the method including generating a STF having one CP and four repeated pattern regions included in a valid symbol interval, Generating an LTF composed of one repetition pattern area included, generating a frame including the STF and the LTF, and transmitting the frame.

Herein, a base sequence element is allocated to odd subcarriers among the repeated pattern regions included in the LTF effective symbol period, and even-numbered subcarriers among the repeated pattern regions included in the LTF effective symbol period are allocated based on the base sequence element The generated transform sequence element may be assigned.

Herein, a base sequence element is allocated to a sub-carrier included in an upper frequency band among the repeated pattern areas included in the valid symbol period of the LTF, and a sub-carrier included in a lower frequency band among the repeated pattern areas included in the valid symbol period of the LTF A modified sequence element generated based on the base sequence element may be assigned.

According to another aspect of the present invention, there is provided a method for transmitting a signal, the method including generating an STF including one CP and four repeated pattern regions included in a valid symbol interval, Generating a CDF composed of one CP and a valid symbol period including information indicating the terminal transmitting the frame, and transmitting the STF, the LTF, and the CDF Generating the frame including the frame, and transmitting the frame.

Herein, information indicating the UE transmitting the frame may be allocated to subcarriers preset for each MS in the valid symbol interval of the CDF.

Here, the information indicating the terminal transmitting the frame may be a busy tone of the physical layer.

According to the present invention, the receiving terminal can acquire accurate time / frequency synchronization, and can detect whether a frame collides with the physical layer. Thus, the efficiency of the communication system can be improved.

1 is a block diagram illustrating an embodiment of a terminal for performing the methods according to the present invention.
2 is a conceptual diagram illustrating the structure of an STF in a wireless LAN system according to the IEEE 802.11 standard.
3 is a flow chart illustrating an embodiment of a single autocorrelation estimation method.
4 is a flowchart showing an embodiment of a double autocorrelation estimation method.
5 is a conceptual diagram showing an embodiment of a preamble structure included in a frame.
6 is a flowchart illustrating a signal transmission method according to an embodiment of the present invention.
7 is a conceptual diagram showing a structure of a first preamble according to the present invention.
8 is a flow chart illustrating an embodiment of a method for detecting collision between frames.
FIG. 9 is a flow chart illustrating an embodiment of a fine time / frequency synchronization estimation method.
10 is a flowchart showing another embodiment of the fine time / frequency synchronization estimation method.
11 is a flow chart illustrating another embodiment of a collision detection method between frames.
12 is a conceptual diagram showing a structure of a second preamble according to the present invention.
13 is a flowchart showing another embodiment of the fine time / frequency synchronization estimation method.
14 is a flowchart illustrating a signal transmission method according to another embodiment of the present invention.
15 is a conceptual diagram showing a structure of a third preamble according to the present invention.
16 is a conceptual diagram showing a structure of a fourth preamble according to the present invention.
17 is a conceptual diagram showing a structure of a fifth preamble according to the present invention.
18 is a conceptual diagram showing a structure of a sixth preamble according to the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Throughout the specification, the network can be, for example, a wireless Internet such as WiFi (wireless fidelity), a wireless broadband internet (WiBro) or a portable internet such as world interoperability for microwave access (WiMax) A 3G mobile communication network such as Wideband Code Division Multiple Access (WCDMA) or CDMA2000, a high speed downlink packet access (HSDPA), or a high speed uplink packet access (HSUPA) A 3.5G mobile communication network, a 4G mobile communication network such as an LTE (Long Term Evolution) network or an LTE-Advanced network, and a 5G mobile communication network.

Throughout the specification, a terminal is referred to as a mobile station, a mobile terminal, a subscriber station, a portable subscriber station, a user equipment, an access terminal, And may include all or some of the functions of a terminal, a mobile station, a mobile terminal, a subscriber station, a mobile subscriber station, a user equipment, an access terminal, and the like.

Here, a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, a smart watch, smart watch, smart glass, e-book reader, portable multimedia player (PMP), portable game machine, navigation device, digital camera, digital multimedia broadcasting (DMB) A digital audio recorder, a digital audio player, a digital picture recorder, a digital picture player, a digital video recorder, a digital video player ) Can be used.

Throughout the specification, a base station is referred to as an access point, a radio access station, a node B, an evolved node B, a base transceiver station, an MMR mobile multihop relay) -BS, and may include all or some of the functions of a base station, an access point, a radio access station, a Node B, an eNodeB, a base transceiver station, and a MMR-BS.

1 is a block diagram illustrating an embodiment of a terminal for performing the methods according to the present invention.

Referring to FIG. 1, a terminal 10 may include at least one processor 11, a memory 12, and a network interface device 13 connected to and performing communication with the network 20. The terminal 10 may further include an input interface device 14, an output interface device 15, a storage device 16, and the like. Each of the components included in the terminal 10 may be connected by a bus 17 and communicate with each other.

The processor 11 may execute program instructions stored in the memory 12 and / or the storage 16. The processor 11 may be a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the methods according to the present invention are performed. The memory 12 and the storage device 16 may be composed of a volatile storage medium and / or a non-volatile storage medium. For example, the memory 12 may be comprised of read only memory (ROM) and / or random access memory (RAM).

Hereinafter, embodiments of the present invention will be described in detail in a communication system based on an orthogonal frequency division multiplexing (OFDM) scheme, but the embodiments of the present invention are not limited or limited to an OFDM communication system. That is, the embodiments of the present invention can be applied not only to an OFDM communication system but also to a single carrier (SC) communication system.

2 is a conceptual diagram illustrating a structure of a short training field (STF) in a wireless LAN system according to the IEEE 802.11 standard.

Referring to FIG. 2, a transmitting terminal can generate an STF including two identical OFDM symbols. Each OFDM symbol may include one cyclic prefix (CP) (e.g., a short CP or a long CP) and four repetition pattern (RP) included in the valid symbol interval. have. The transmitting terminal can generate the CP by copying the last repeated pattern area RP included in the valid symbol period into the CP section. Therefore, one OFDM symbol may include five repeated pattern regions RP.

The transmitting terminal can allocate a sequence element to a subcarrier among the repeated pattern regions RP included in the valid symbol period. For example, the transmitting terminal can allocate the sequence elements E1, E2, ... for every four subcarriers in the effective frequency band of each repeated pattern region RP. That is, the transmitting terminal can generate each repetitive pattern area RP by allocating a sequence element for each of four sub-carriers in the effective frequency band and performing an inverse fast fourier transform (IFFT) on the area to which the sequence element is allocated.

Meanwhile, the receiving terminal can receive the frame including the STF generated in the above-described manner. The receiving terminal can perform an auto gain control process, a packet estimation process, and an initial time / frequency synchronization estimation process based on the STF. When one OFDM symbol among the OFDM symbols included in the STF is allocated for the automatic gain adjustment process, the receiving terminal estimates a packet based on the repeated pattern areas included in the remaining OFDM symbols included in the STF, And an initial time / frequency synchronization estimation process.

Here, the packet estimation process is generally performed by determining whether the maximum value of the correlator exceeds the threshold value at the initial time / frequency synchronization estimation, so that a separate packet estimation process is not required. In the case of performing the packet estimation process and the initial time / frequency synchronization estimation process using one OFDM symbol, since the number of samples in the repeated pattern area is small, the receiving terminal can not accurately measure time / frequency synchronization due to low SNR (Signal to Noise Ratio) Frequency synchronization can not be estimated.

3 is a flow chart illustrating one embodiment of a single auto-correlation estimation method.

Referring to FIG. 3, Z denotes a delay function, N _D denotes one repeated pattern region,

Is delayed by N _D. (y) ^* means a conjugating process of y (that is, a process of inverting the sign of the imaginary part while keeping the real part of y), and X means mathematical multiplication. The moving sum function is a function to add a multiplication value of an input signal for a predetermined period. On the other hand, when the preset interval has passed, the mobile sum function adds the multiplication value of the first inputted signal to the multiplier of the newly inputted signal based on the first input first output (FIFO) The result value R can be updated. (R) means the absolute value of the result value R, and MAX () means that the maximum value among the absolute values of the signals estimated during the predetermined section is selected.

In the case of estimating the correlation between neighboring repeated pattern regions based on the single autocorrelation estimation method, if the number of samples included in the repeated pattern region is small, the SNR is lowered due to a large influence by noise, do. In order to compensate for this, it is possible to assign a sequence element having an excellent autocorrelation characteristic to the repetitive pattern region, but this method is not a perfect solution when the influence on the noise is great. On the other hand, a double auto-correlatin estimation method can be considered to reduce the influence of noise.

4 is a flowchart showing an embodiment of a double autocorrelation estimation method.

Referring to FIG. 4, Z denotes a delay function, N _D denotes one repeated pattern region,

Lt; RTI _ID = 0.0 > N _D , < / RTI &

It is meant to delayed by _D 2N. (y) ^* denotes the conjugation process of y (that is, the process of inverting the sign of the imaginary part while keeping the real part of y), + denotes mathematical addition, and X denotes mathematical multiplication. The moving sum function means a function of adding a multiplication value of an input signal for a predetermined period. On the other hand, if the preset interval has passed, the mobile sum function removes the multiplication value of the first input signal based on the FIFO scheme, adds the multiplication value of the newly input signal, and adds the result value R Can be updated. (R) means the absolute value of the result value R, and MAX () means that the maximum value among the absolute values of the signals estimated during the predetermined section is selected.

The double auto correlation estimation method is a method of performing addition between the sequence elements included in the first and second neighboring repeat pattern regions and the sequence elements included in the current repeat pattern region. However, if there is a difference between the transmit and receive carrier frequencies (i.e., there is a frequency offset), the synchronization offset performance of the dual autocorrelation estimation method degrades due to the phase offset between the two autocorrelation estimates.

5 is a conceptual diagram showing an embodiment of a preamble structure included in a frame.

Referring to FIG. 5, D denotes one repetition pattern area included in the STF, E denotes one repetition pattern area included in LTF, and E 'denotes CP generated based on E.

The preamble may include STF, LTF. The STF can be composed of two symbols. Each symbol included in the STF may be composed of one CP (for example, short CP) and four repetition pattern areas included in the valid symbol interval. The first symbol included in the STF may be used for the automatic gain adjustment process, and the second symbol included in the STF may be used for the packet estimation process and the initial time / frequency synchronization estimation process.

LTF may be composed of one CP (for example, long CP) and two repetition pattern areas included in the valid symbol period. One CP and two repetition pattern areas may be included in two symbol intervals. Repeated pattern regions included in the LTF can be used for fine time / frequency synchronization estimation and channel estimation.

On the other hand, although the LTF can perform a fine time / frequency synchronization estimation process and a channel estimation process with only one symbol included in the LTF, there is a problem that resources are wasted because the LTF includes two symbols. That is, if time synchronization can be estimated in the CP based on the STF, and the frequency offset can be compensated, the receiving terminal can perform a precise time / frequency synchronization estimation process and a channel estimation process using only one symbol included in the LTF .

FIG. 6 is a flowchart illustrating a signal transmission method according to an embodiment of the present invention, and FIG. 7 is a conceptual diagram illustrating a structure of a first preamble according to the present invention.

6 and 7, a transmitting terminal may refer to a communication entity that transmits a frame to a receiving terminal, and may refer to a base station as well as a terminal. The receiving terminal may mean a communication entity receiving a frame from a transmitting terminal, and may mean a base station as well as a terminal. Here, D means one repetition pattern region included in the STF, E means one repetition pattern region included in LTF, and E "means CP generated based on E.

The transmitting terminal can generate an STF including an effective symbol interval including one CP and a predetermined number of repeated pattern regions (S100). Here, one CP and an effective symbol interval may be included in two symbol intervals. A CP can mean a short CP or a long CP. The transmitting terminal can generate the CP by copying the last repetitive pattern area included in the valid symbol period into the CP section. The predetermined number may be smaller than the number (for example, eight (see FIG. 2)) of repeated pattern regions included in the effective symbol period of the conventional STF. For example, the transmitting terminal can generate an effective symbol interval including four repeating pattern areas.

The transmitting terminal may set the polarity of an arbitrary repetitive pattern area of the repeated pattern areas included in the valid symbol interval of the STF differently to indicate the transmission mode of the frame. For example, the transmitting terminal may indicate that the frame is transmitted in the OFDM scheme by setting the polarity of the first repeated pattern area in the effective symbol interval of the STF to (+), By setting the polarity to (-), it can indicate that the frame is transmitted in the SC scheme.

The transmitting terminal can set the polarity of the last repetitive pattern area included in the valid symbol period of the STF to be opposite to the polarity of the previous repetitive pattern area to indicate the end of the STF. For example, the transmitting terminal can inform the end of the STF by setting the polarity of the last repetitive pattern area to (-) when the polarity of the previous repetitive pattern area is (+). On the other hand, if the polarity of the previous repetitive pattern area is negative, the transmitting terminal can notify the end of the STF by setting the polarity of the last repetitive pattern area to (+).

The transmitting terminal can allocate the sequence elements to the odd subcarrier or the even subcarrier among the effective frequency bands of each repeated pattern region included in the valid symbol interval of the STF. In this case, the transmitting terminal can alternately allocate the base sequence element and the transformed sequence element generated based on the base sequence element to odd subcarriers. Alternatively, the transmitting terminal may alternately assign the base sequence element and the transformed sequence element generated based on the base sequence element to the even subcarriers. Here, the sequence element may mean a ZC (zadoff-chu) sequence element. Sequence elements used in embodiments of the present invention are not limited to ZC sequence elements, and any complex sequence element, any binary sequence element may be used.

The transmitting terminal may generate the ZC sequence element [alpha] _u (k) based on Equation (1) below.

Here, k denotes a subcarrier index, U denotes an index of a sequence element, and N _G denotes a length of a ZC sequence element. The transmitting terminal may generate a base sequence element (b _v (k)) based on the ZC sequence element.

Here, k denotes a subcarrier index, and V refers to the index of the sequence element, and N _P denotes the length of the sequence element. The transmitting terminal may generate a modified sequence element m _v (k) based on the base sequence element b _v (k).

Here, b _v (k) means a base sequence element, and k denotes a subcarrier index, and V refers to the index of the sequence element, and N _P denotes the length of the sequence element.

When a sequence element is allocated to odd subcarriers among the repeated pattern regions included in the effective symbol interval of the STF, the transmitting terminal can allocate a first base sequence element (b _v (0)) to the first subcarrier, the first may be assigned a modified sequence element (m _v (0)), five second may assign a base sequence element (b _v (1)) in the sub-carrier, a second modification to the seventh sub-carrier to sub-carrier The sequence element m _v (1) can be allocated. Conversely, the transmitting terminal may allocate a first variant sequence element _mv (0) to the first subcarrier, allocate a first base sequence element _bv (0) to the third subcarrier, the sub-carrier a second modified sequence element (m _v (1)) are bound to, may assign a second base sequence element (b _v (1)) in the seventh sub-carrier.

When a sequence element is allocated to even-numbered subcarriers among the repeated pattern regions included in the effective symbol interval of the STF, the transmitting terminal can allocate a first base sequence element (b _v (0)) to the second subcarrier, first modified sequence element (m _v (0)) you are bound to, six may be assigned to a second base sequence element (b _v (1)) in the sub-carrier, a second modification to the eighth sub-carrier to sub-carrier The sequence element m _v (1) can be allocated. Conversely, the transmitting terminal may allocate a first variant sequence element _mv (0) to a second subcarrier, allocate a first base sequence element _bv (0) to a fourth subcarrier, the sub-carrier a second modified sequence element (m _v (1)) are bound to, may assign a second base sequence element (b _v (1)) in the eighth sub-carrier.

Meanwhile, the transmitting terminal may allocate base sequence elements to odd subcarriers or even subcarriers included in the upper valid frequency band among the repeated pattern regions included in the effective symbol interval of the STF, And a deformation sequence element may be allocated to an odd subcarrier or an even subcarrier included in a lower effective frequency band among the repeated pattern regions. On the other hand, the transmitting terminal can allocate the deinterleaver sequence elements to the odd subcarrier or the even subcarrier included in the upper valid frequency band among the repeated pattern regions included in the valid symbol interval of the STF, The base sequence element may be allocated to the odd subcarrier or the even subcarrier included in the lower effective frequency band among the repeated pattern regions. The transmitting terminal can generate the base sequence element based on Equation (2) and generate the modified sequence element m _v (k) based on Equation (4) below.

Here, b _v (k) denotes a base sequence element, k denotes a subcarrier index, V denotes an index of a sequence element, () ^* denotes conjugation (that is, the sign of the imaginary part Inversion).

For example, the transmitting terminal may allocate a first base sequence element (b _v (0)) to a first subcarrier of an upper significant frequency band among each repeated pattern region included in an effective symbol interval of the STF, (B _v (1)) to the fifth base sequence element (b _v (2)) and allocate the third base sequence element b _v (2) to the fifth subcarrier. Also, the transmitting terminal allocates the first transformed sequence element _mv (0) generated on the basis of Equation (4) to the second subcarrier of the lower effective frequency band among the respective repeated pattern regions included in the valid symbol interval of the STF And assigns a second modified sequence element _mv (1) generated based on Equation (4) to a fourth subcarrier, and assigns a third modified sequence element _mv (1) generated on the third subcarrier based on Equation A transformation sequence element _mv (2) may be allocated.

The transmitting terminal can generate an LTF composed of one CP and a valid symbol period including a predetermined number (e.g., two) of repeated pattern regions (S110). Here, one CP and an effective symbol interval may be included in two symbol intervals. A CP can mean a short CP or a long CP. The transmitting terminal can generate the CP by copying the last repetitive pattern area included in the valid symbol period into the CP section.

The transmitting terminal may set the polarity of any repetitive pattern area among the repeated pattern areas included in the valid symbol period of the LTF differently to indicate the transmission mode of the frame. For example, the transmitting terminal may indicate that the frame is transmitted in the OFDM scheme by setting the polarity of the first repetitive pattern region of the LTF as positive (+), By setting the polarity to (-), it can indicate that the frame is transmitted in the SC scheme.

The transmitting terminal may allocate base sequence elements to odd subcarriers among effective frequency bands of each repetitive pattern area included in the LTF effective symbol period and allocate modified sequence elements generated based on base sequence elements to even subcarriers can do. Conversely, the transmitting terminal may assign a deformation sequence to odd subcarrier elements of the effective frequency band of each repetitive pattern area included in the valid symbol interval of the LTF, and may assign base sequence elements to even-numbered subcarriers. Here, the sequence element may mean a ZC sequence element. Sequence elements used in embodiments of the present invention are not limited to ZC sequence elements, and any complex sequence element, any binary sequence element may be used.

The transmitting terminal may generate the base sequence element b _z (k) based on Equation (5) below.

Here, k denotes a subcarrier index, Z denotes an index of a sequence element, and _NQ denotes a length of a sequence element.

The transmitting terminal may generate the transformed sequence element m _z (k) based on Equation 6 below.

Here, b _z (k) denotes a base sequence element, k denotes a subcarrier index, Z denotes an index of a sequence element, and N _Q denotes a length of a sequence element.

For example, the transmitting terminal may allocate a first base sequence element (b _z (0)) to a first subcarrier of each repeated pattern region included in an effective symbol interval of LTF, element (m _z (0)) may be assigned to, it is possible to assign a second base sequence element (b _z (1)) in the third sub-carrier, a second modified sequence element (m _z (1 to the fourth sub-carrier )) Can be assigned. Conversely, the transmitting terminal may first allocate the deinterleaver sequence element to the frequency band among the repeated pattern regions included in the valid symbol period of the LTF, and then allocate the base sequence element.

On the other hand, the transmitting terminal can allocate the base sequence element to each subcarrier included in the upper effective frequency band among the repeated pattern regions included in the valid symbol interval of the LTF, allocate the base sequence element to each subcarrier included in the lower effective frequency band, Can be assigned. On the other hand, the transmitting terminal can allocate the transformed sequence elements to subcarriers included in the upper valid frequency band among the respective repeated pattern regions included in the valid symbol period of the LTF, allocate the transformed sequence elements to the subsequential subcarriers included in the lower effective frequency band, Can be assigned. The transmitting terminal can generate the base sequence element based on Equation (5) above and generate the modified sequence element m _z (k) based on Equation (7) below.

For example, the transmitting terminal may assign a first base sequence element (b _z (0)) to a first subcarrier included in an upper significant frequency band of each repeated pattern region included in an effective symbol interval of an LTF, The second base sequence element b _z (1) may be allocated to the third subcarrier, and the third base sequence element b _z (2) may be allocated to the third subcarrier. Also, the transmitting terminal transmits the first transformed sequence element m _z (0) generated on the basis of Equation (7) to the first subcarrier included in the lower effective frequency band of each repeated pattern region included in the valid symbol period of the LTF, And assigns the second modified sequence element m _z (1) generated based on Equation (7) to the second subcarrier, and assigns the second modified sequence element m _z A third modified sequence element m _z (2) may be allocated.

The transmitting terminal can generate a frame including STF and LTF generated through the above process (S120), and transmit the generated frame to the receiving terminal (S130).

The receiving terminal may perform an automatic gain adjustment process, a packet estimation process, and an initial time / frequency synchronization estimation process based on the STF included in the received frame (S140). The receiving terminal can perform the automatic gain adjustment process through the energy detection scheme based on the two or less repeated pattern regions included in the STF (i.e., the first and second repeated pattern regions). Specifically, the receiving terminal can acquire the sum or average of the received signal strength or the received power intensity over a predetermined interval, and adjust the gain of the amplifier such that the obtained value is a preset reference value.

After performing the automatic gain adjustment process, the receiving terminal performs an initial time / frequency synchronization estimation process based on the single autocorrelation estimation method (or the double autocorrelation estimation method described with reference to FIG. 4) described with reference to FIG. can do. Specifically, the receiving terminal can perform conjugation on the Nth repeated pattern region signal, multiply the conjugated Nth repeated pattern region signal and the (N-1) th repeated pattern region signal during the repeated pattern region period, If the region of the repetitive pattern area is past, it is possible to remove the first multiplication value in the FIFO concept and update the result value based on the newly inputted product value.

Thereafter, the receiving terminal may generate an absolute value for the resultant value and the resultant value for the repeated pattern area signal for a predetermined window period from the first repeated pattern area period. The receiving terminal can estimate the starting point of the repetitive pattern area signal having the largest value among the generated absolute values as the initial time synchronization point and perform the initial frequency synchronization estimation process based on the phase corresponding to the estimated initial time synchronization point Can be performed. That is, the receiving terminal can estimate the frequency offset, which is the difference between the transmission / reception carrier frequencies, from the phase corresponding to the initial time synchronization point, and can perform the frequency synchronization by applying the estimated frequency offset to the input repeated pattern area signal .

At the same time, the receiving terminal can compare the absolute value of the resultant value at the initial time synchronization point with a preset threshold value (i.e., a packet estimation process). If the absolute value is smaller than the threshold value, the receiving terminal may not perform the following process. On the other hand, if the absolute value is greater than or equal to the threshold value, the receiving terminal can perform the following process.

Meanwhile, the receiving terminal may perform a packet estimation process, an initial time / frequency synchronization estimation process, and then detect a collision between frames based on the STF.

8 is a flow chart illustrating an embodiment of a method for detecting collision between frames.

Referring to FIG. 8, a receiving terminal performs an initial time / frequency synchronization estimation process and then performs a discrete fourier transform (DFT) on an effective symbol interval of a signal compensated based on a result of the initial time / frequency synchronization estimation A fast Fourier transform (FFT) can be performed. The receiving terminal can extract a non-nulled subcarrier signal among the subcarriers of the effective symbol interval through an extractor. If the frequency domain signal is composed of one sequence element during the extraction process, the receiving terminal can extract the corresponding subcarrier signal as it is.

If, on the other hand, the frequency domain signal consists of a base sequence element and a base sequence element and a base sequence element, then the receiving terminal is configured to receive a base sequence element and a transform sequence element corresponding to the base sequence element Despreading process (that is, in the case of reducing the transformed sequence element to the original base sequence element), the transforming process of the transformed sequence element is applied to the subcarrier to which the transformed sequence element is allocated, and the original base sequence A process of performing addition between subcarriers to which an element is assigned and a subcarrier to which a degenerating sequence element is subjected to a dequantization process) can be performed and the despread signal can be extracted. The signal S (k) extracted through this process is expressed by Equation (8) below.

Here, g denotes an index of a base sequence element,? Denotes an average received power, M denotes a length of an extracted signal, k denotes a subcarrier index, and H (k) denotes a channel frequency Response, and w means noise.

The receiving terminal may perform differential encoding on S (k) to generate V (k) as shown in Equation (9).

Thereafter, the receiving terminal may perform an inverse DFT (IDEF) or an IFFT on V (k). Here, a signal on which IDEF or IFFT is performed is called X (n). The receiving terminal may obtain a peak to average power ratio (PAPR) for X (n) based on Equation (10).

The receiving terminal can determine that a collision between frames occurs when the PAPR is equal to or less than a preset threshold value C and conversely if the PAPR is greater than the predetermined threshold value C, can do. The receiving terminal can determine the final collision based on the STF-based collision detection or the final collision based on the STF-based collision detection result and the LTF-based collision detection result described below.

Referring to FIGS. 6 and 7 again, the receiving terminal can perform a fine time / frequency synchronization estimation process and a channel estimation process based on the LTF included in the frame (S150).

FIG. 9 is a flow chart illustrating an embodiment of a fine time / frequency synchronization estimation method.

Referring to FIG. 9, D denotes one repetitive pattern region included in the STF, -D denotes a repetitive pattern region having an opposite polarity, E denotes a repetitive pattern region included in the LTF, E "refers to CP generated based on E.

The receiving terminal receives the conjugated value of the initial frequency-synchronized time-domain signals (x (k)) at a starting point separated by N _D (i.e., one repeated pattern region) from the initial time synchronization point and the conjugated value of the STF (K = 1, 2, 3, ...) for the last two repeated pattern regions (i.e., 2N _D ) The correlation value for each region can be estimated. At this time, the receiving terminal can estimate the correlation value for each repetitive pattern area based on Equation (11) below.

Here, N _D denotes a single repeating pattern area, and, T _S denotes a distance starting point as N _D, and x (k) refers to the coarse frequency synchronization time domain signal, y (k) is the end of the STF Denotes a time domain signal for two repetitive pattern regions, and k denotes a subcarrier index.

In addition, the receiving terminal receives the time-domain signal synchronized with the initial frequency at a starting point 3N _D away from the initial time synchronization point, and the signal between the CP included in the LTF known to all terminals and the signal for the first repeated pattern region of the valid symbol interval The correlation value estimation can be estimated by performing the correlation estimation for each repetition pattern area.

The receiving terminal may multiply the first estimated cross-correlation value and the second estimated cross-correlation value to obtain a final cross-correlation value for each repeated pattern region. The receiving terminal can determine the signal index corresponding to the maximum value among the final correlation values as a fine time synchronization point through a peak detector. The receiving terminal can perform a precise frequency synchronization estimation process based on the phase of the result obtained by multiplying the value obtained by conjugating the first cross-correlation value and the value conjugated with the second cross-correlation value at the fine time synchronization point. That is, the receiving terminal can estimate the frequency offset based on the phase, and estimate the fine frequency offset by applying the estimated frequency offset to the received signals.

6 and 7, after performing detailed time / frequency synchronization estimation, the receiving terminal can perform a channel estimation process. The receiving terminal can perform FFT or DFT on the first repetitive pattern area of the LTF effective symbol interval at the precise time synchronization point and remove the base sequence element and the transform sequence element among the FFT or DFT- To convert the sequence element to 1 by performing conjugation) to obtain a first signal for each subcarrier. In a similar manner, the receiving terminal can perform an FFT or a DFT on the second repetitive pattern region of the LTF effective symbol interval at a fine time synchronization point, and perform the FFT or DFT on the base sequence element and the transformed sequence element The second signal for each subcarrier can be obtained. The receiving terminal can finally estimate the channel for each subcarrier by adding the first signal and the second signal.

Meanwhile, the receiving terminal can perform the initial time / frequency synchronization estimation process and the fine time / frequency synchronization estimation process using only the STF.

10 is a flowchart showing another embodiment of the fine time / frequency synchronization estimation method.

Referring to FIG. 10, D denotes one repetitive pattern area included in the STF, and -D denotes a repetitive pattern area having an opposite polarity. The initial time / frequency synchronization estimation method is the same as the method described with reference to FIG. 6 and FIG. The fine time / frequency synchronization estimation method is performed based on the method described with reference to FIG. 9, but differs from the method described with reference to FIG. 9 in that only the first correlation estimation is performed.

On the other hand, the receiving terminal can detect a collision between frames based on the LTF.

11 is a flow chart illustrating another embodiment of a collision detection method between frames.

Referring to FIG. 11, a receiving terminal performs a detailed time / frequency synchronization estimation process, and performs a DFT or an FFT on an effective symbol interval of a signal compensated based on the result of the estimation (i.e., the frequency offset is compensated) have. The receiving terminal may perform a combining process of adding the same subcarriers included in the two repeating pattern areas through a combiner. If the frequency domain signal is composed of one sequence element during the combining process, the receiving terminal can output the corresponding subcarrier as it is.

On the other hand, if the frequency domain signal is composed of a base sequence element and a transform sequence element, the receiving terminal performs a despreading process between the base sequence element and the transform sequence element corresponding to the base sequence element (i.e., the sequence element transformed from the specific base sequence element) (I.e., when reducing the transformed sequence element to the original base sequence element, the reduction process of the transformed sequence element is applied to the subcarriers to which the transformed sequence element is assigned, and the subcarriers to which the original base sequence element is allocated and the transformed sequence elements A process of performing addition between sub-carriers to which a process is applied). The receiving terminal can extract the despread signal through this process. Here, the despreaded signal can be regarded as the final combined signal. The final combined signal S (k) is shown in Equation (8).

The receiving terminal may perform a differential encoding process on the finally combined signal S (k) based on Equation (9) to generate the signal V (k). The receiving terminal may perform an IDFT or an IFFT on the signal V (k) to generate the signal X (k). The receiving terminal may calculate the PAPR for the signal X (k) based on Equation (10). The receiving terminal can determine that a collision between frames occurs when the PAPR is equal to or less than the predetermined threshold value C and can determine that the collision does not occur when the PAPR is greater than the predetermined threshold value C . The receiving terminal can judge the final collision by comprehensively considering the collision detection result based on the STF and the collision detection result based on the LTF.

12 is a conceptual diagram showing a structure of a second preamble according to the present invention.

Referring to FIG. 12, D denotes one repetitive pattern region included in the STF, -D denotes a repetitive pattern region having an opposite polarity, E denotes a repetitive pattern region included in the LTF, E 'means CP generated based on E.

The STF may be composed of one CP and four repetition pattern areas included in the valid symbol interval. One CP and four repetition pattern areas can be included in two symbol intervals. A CP can mean a short CP or a long CP. CP may have the same shape as the last repetitive pattern area included in the valid symbol interval (i.e., the fourth repetitive pattern area). That is, since the structure of the STF is the same as the structure of the STF shown in FIG. 7, the transmitting terminal can generate the STF in the same manner as the step S100 described with reference to FIG.

LTF may be composed of one CP and one repetition pattern area included in the valid symbol interval. One CP and one repetition pattern area may be included in one symbol interval. A CP can mean a short CP or a long CP. The CP may have the same shape as the last part of the repeated pattern area included in the valid symbol period. The structure of the LTF differs from that of the LTF shown in Fig. 7 in that it is composed of one symbol. Therefore, the transmitting terminal can generate the LTF based on S110 described with reference to FIG. 6 except for the structurally different part.

Meanwhile, the receiving terminal can perform the packet estimation process and the initial time / frequency estimation process in the same manner as the method described with reference to FIG. 6 and FIG. The receiving terminal can perform a detailed time / frequency estimation process and a channel estimation process based on the method described with reference to FIG. However, the detailed time / frequency estimation process and channel estimation process performed in the receiving terminal differs from the method described with reference to FIG. 9 in that resources used are different.

13 is a flowchart showing another embodiment of the fine time / frequency synchronization estimation method.

Referring to FIG. 13, D denotes one repeated pattern region included in the STF, -D denotes a repetitive pattern region having an opposite polarity, E denotes a repetitive pattern region included in the LTF, E 'means CP generated based on E.

Since the resources used for the detailed time / frequency synchronization estimation process are half of the resources used in the method described with reference to FIG. 9, fine time / frequency synchronization estimation performance may be degraded. To prevent this, the receiving terminal can use a fourier transform (FT) based channel estimation technique. The receiving terminal may perform an FFT or a DFT on the repetitive pattern area included in the valid symbol interval of the LTF and may remove the base sequence element and the deformation sequence element from the FFT or DFT processed signal, Lt; RTI ID = 0.0 > IFFT < / RTI > or IDFT. The receiving terminal can allocate the remaining part to 0 by leaving only the part of the signal in which the IFFT or the IDFT is performed for the first CP interval (or longer than the CP interval or the shorter interval), and then the FFT or DET To thereby estimate a channel for each subcarrier.

FIG. 14 is a flowchart illustrating a signal transmission method according to another embodiment of the present invention, and FIG. 15 is a conceptual diagram illustrating a structure of a third preamble according to the present invention.

14 and 15, a transmitting terminal may refer to a communication entity transmitting a frame to a receiving terminal, and may refer to a base station as well as a terminal. The receiving terminal may mean a communication entity receiving a frame from a transmitting terminal, and may mean a base station as well as a terminal. Here, D means one repeated pattern region included in the STF, and -D means a repeated pattern region having the opposite polarity. E denotes one repetition pattern area included in LTF, and E 'denotes CP generated based on E. R denotes one repetition pattern area included in the CDF, and R 'denotes a CP generated based on R.

The transmitting terminal can generate an STF including an effective symbol interval including one CP and a predetermined number of repeated pattern regions (S200). One CP and an effective symbol interval may be included in two symbol intervals. A CP can mean a short CP or a long CP. The transmitting terminal can generate the CP by copying the last repetitive pattern area included in the valid symbol period into the CP section. The predetermined number may be smaller than the number (for example, eight (see FIG. 2)) of repeated pattern regions included in the effective symbol period of the conventional STF. For example, the transmitting terminal can generate an effective symbol interval including four repeating pattern areas. The transmitting terminal can generate the STF in the same manner as in step S100 described with reference to FIG.

The transmitting terminal can generate an LTF composed of one CP and one repeated pattern region included in the valid symbol interval (S210). One CP and one repetition pattern area may be included in one symbol interval. A CP can mean a short CP or a long CP. The transmitting terminal can generate the CP by copying the last part of the repeated pattern area included in the valid symbol section into the CP section. The LTF structure differs from the LTF structure shown in Fig. 7 in that it is composed of one symbol. Therefore, the transmitting terminal can generate the LTF based on S110 described with reference to FIG. 6 except for the structurally different part.

The transmitting terminal may generate a collision detection field (CDF) composed of a valid CP and a valid symbol period including information indicating a terminal transmitting the frame (S220). One CP and an effective symbol interval may be included in one symbol interval. A CP can mean a short CP or a long CP. The transmitting terminal can generate the CP by copying the last part of the information included in the valid symbol interval into the CP interval.

The transmitting terminal may assign information (hereinafter, referred to as 'frame transmission terminal information') indicating that the transmitting terminal itself transmits the current frame to at least one subcarrier set in the frequency band of the valid symbol interval included in the CDF. In this case, the transmitting terminal can allocate the frame transmitting terminal information to the entire time domain of the preset subcarrier. That is, since frames transmitted from a plurality of transmitting terminals arrive at specific receiving terminals at different times, it is difficult for the receiving terminal to accurately detect frames in the frequency domain. In order to prevent this, the transmitting terminal may allocate the frame transmitting terminal information to the entire time domain.

The transmitting terminal allocates a busy signal (that is, busy tone) of the physical layer to at least one subcarrier preset for each terminal in the frequency band of the effective symbol interval included in the CDF, thereby transmitting the current frame Lt; / RTI >

When the frame transmission terminal information is allocated to two subcarriers, the transmitting terminal can classify the effective frequency band of the effective symbol interval included in the CDF into two groups (i.e., a higher effective frequency band and a lower effective frequency band) A busy tone can be allocated to one subcarrier of the upper effective frequency band and a busy tone can be allocated to one subcarrier of the lower effective frequency band. Here, the position of the subcarrier of the upper effective frequency band to which the busy tone is allocated may be the same as or different from the position of the subcarrier of the lower effective frequency band to which the busy tone is allocated.

When the transmission terminal information of the frame is allocated to four subcarriers, the transmitting terminal divides the effective frequency band of the effective symbol interval included in the CDF into four groups (i.e., the first effective frequency band, the second effective frequency band, Frequency band, and fourth effective frequency band), and a busy tone can be allocated to one sub-carrier included in each group.

The transmitting terminal can generate a frame including STF, LTF and CDF (S230), and transmit the generated frame to the receiving terminal (S240). The receiving terminal may perform a packet estimation process and an initial time / frequency synchronization estimation process based on the STF included in the frame (S250). Here, the receiving terminal may perform a packet estimation process and an initial time / frequency synchronization estimation process in the same manner as in step S140 described with reference to FIG. Also, the receiving terminal can detect a collision between frames based on the method described with reference to FIG.

The receiving terminal may perform a fine time / frequency synchronization estimation process and a channel estimation process based on the LTF included in the frame (S260). Here, the receiving terminal can perform a fine time / frequency synchronization estimation process and a channel estimation process based on the method described with reference to FIG.

The receiving terminal may detect a collision between the frames based on the CDF included in the frame (S270). The receiving terminal may perform an FFT or a DFT at a starting point (i.e., a fine time synchronization point) of an effective symbol interval included in the CDF. The receiving terminal can compare the signal strength of each subcarrier subjected to the FFT or DFT with a predetermined threshold value and count the number of subcarriers having a signal strength greater than a predetermined threshold value.

When a scheme in which frame transmission terminal information is allocated to two subcarriers is used, the receiving terminal can determine that a collision has occurred between frames when the number of counted subcarriers exceeds two, and if the number of counted subcarriers is If it is less than 2, it can be judged that no collision occurs between the frames.

When a method in which frame transmission terminal information is allocated to four subcarriers is used, the receiving terminal can determine that a collision has occurred between frames when the number of counted subcarriers exceeds four, If the number of frames is four or less, it can be determined that no collision occurs between the frames.

16 is a conceptual diagram showing a structure of a fourth preamble according to the present invention.

Referring to FIG. 16, A denotes a repetitive pattern area included in the first symbol of the STF, D denotes a repetitive pattern area included in the second symbol of the STF, and -D denotes a repetitive pattern area having an opposite polarity , And D 'means CP generated based on D. E denotes a repetitive pattern region included in the LTF, -E denotes a repetitive pattern region having an opposite polarity, and E 'denotes a CP generated based on E.

The preamble may include STF, LTF. The STF can be composed of two symbols. The first symbol of the STF may consist of one CP (i.e., a short CP or a long CP), and four repeating pattern regions included in the valid symbol interval. The second symbol of the STF may consist of one CP (i.e., a short CP or a long CP), and two repeating pattern regions included in the valid symbol interval. Here, the structure of the STF differs from the structure of the STF shown in FIG. Therefore, the transmitting terminal can generate the STF based on S100 described with reference to FIG. 6 except for the structurally different part.

LTF may be composed of one CP (i.e., a short CP or a long CP), and two repetitive pattern regions included in the valid symbol interval. One CP and two repetition pattern areas may be included in two symbol intervals. Here, the structure of the LTF is the same as that of the LTF shown in Fig. Accordingly, the transmitting terminal can generate the LTF based on S110 described with reference to FIG.

17 is a conceptual diagram showing a structure of a fifth preamble according to the present invention.

Referring to FIG. 17, A denotes a repetitive pattern area included in the first symbol of the STF, D denotes a repetitive pattern area included in the second symbol of the STF, and -D denotes a repetitive pattern area having an opposite polarity , And D 'means CP generated based on D. E denotes the repetitive pattern area included in the LTF, and E 'denotes the CP generated based on E.

The LTF may be composed of one CP (i.e., a short CP or a long CP), and one repeated pattern region included in the valid symbol period. One CP and one repetition pattern area may be included in one symbol interval. Here, the structure of the LTF is the same as that of the LTF shown in Fig. Therefore, the transmitting terminal can generate the LTF in the same manner as the method of generating the LTF shown in Fig.

18 is a conceptual diagram showing a structure of a sixth preamble according to the present invention.

Referring to FIG. 18, A denotes a repetitive pattern area included in the first symbol of the STF, D denotes a repetitive pattern area included in the second symbol of the STF, and -D denotes a repetitive pattern area having an opposite polarity , And D 'means CP generated based on D. E denotes the repetitive pattern area included in the LTF, and E 'denotes the CP generated based on E. R denotes a repetitive pattern area included in the CDF, and R 'denotes a CP generated based on R.

The LTF may be composed of one CP (i.e., a short CP or a long CP), and one repeated pattern region included in the valid symbol period. One CP and one repetition pattern area may be included in one symbol interval. Here, the structure of the LTF is the same as that of the LTF shown in Fig. Therefore, the transmitting terminal can generate LTF based on S210 described with reference to FIG.

The CDF may be composed of one CP (i.e., a short CP or a long CP), and a valid symbol period including information indicating a terminal transmitting the frame. One CP and an effective symbol interval may be included in one symbol interval. Here, the structure of the CDF is the same as that of the CDF shown in Fig. Therefore, the transmitting terminal can generate the CDF based on S220 described with reference to FIG.

Embodiments of the present invention may be implemented in the form of program instructions that can be executed on various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. Program instructions to be recorded on a computer-readable medium may be those specially designed and constructed for embodiments of the present invention or may be available to those skilled in the art of computer software.

The computer-readable medium may refer to a hardware device that is specifically configured to store and execute program instructions, such as a ROM, a RAM, a flash memory, and the like. A hardware device may be configured to operate with at least one software module to perform operations in accordance with embodiments of the present invention, and vice versa. A program instruction may refer to a high-level language code that may be executed on a computer based on, for example, an interpreter, as well as machine code as produced by a compiler.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims

A signal transmission method performed in a terminal,
Generating a short training field (STF) composed of four repetitive pattern areas included in one CP (cyclic prefix) and an effective symbol section;
Generating a long training field (LTF) composed of one CP and two repetition pattern areas included in the valid symbol interval;
Generating a frame including the STF and the LTF; And
And transmitting the frame.

The method according to claim 1,
Wherein a polarity of an arbitrary repetition pattern area among four repetition pattern areas included in an effective symbol interval of the STF is set differently according to a transmission mode of the frame.

The method according to claim 1,
Wherein the polarity of the last repetitive pattern region among the four repetitive pattern regions included in the valid symbol period of the STF is set to be opposite to the polarity of the previous repetitive pattern region to indicate the end of the STF.

The method according to claim 1,
Wherein a sequence element is allocated to odd-numbered or even-numbered subcarriers of each repetition pattern area included in an effective symbol interval of the STF.

The method of claim 4,
Wherein a base sequence element and a transform sequence element generated based on the base sequence element are alternately allocated to the odd-numbered or even-numbered subcarriers.

The method of claim 4,
Wherein a base sequence element is allocated to odd-numbered or even-numbered subcarriers included in an upper frequency band of each of the repetition pattern areas, and the base sequence element is allocated to odd-numbered or even-numbered subcarriers included in a lower frequency band, And the generated sequence elements are assigned to the base station.

The method according to claim 1,
Wherein a polarity of an arbitrary repetition pattern area among two repetition pattern areas included in an effective symbol period of the LTF is set differently according to a transmission mode of the frame.

The method according to claim 1,
Base sequence elements are assigned to odd subcarriers of each repetition pattern area included in the LTF valid symbol interval, and even-numbered subcarriers of each repetition pattern area included in an effective symbol interval of the LTF are allocated based on the base sequence element And the generated deformation sequence element is assigned.

The method according to claim 1,
A base sequence element is allocated to a subcarrier included in an upper frequency band of each repetition pattern area included in an effective symbol interval of the LTF, and a subsequence element included in a lower frequency band of each repetition pattern area included in an effective symbol interval of the LTF Wherein a modified sequence element generated based on the base sequence element is assigned to the base sequence element.

A signal transmission method performed in a terminal,
Generating a short training field (STF) composed of four repetitive pattern areas included in one CP (cyclic prefix) and an effective symbol section;
Generating a long training field (LTF) composed of one CP and one repetition pattern area included in the valid symbol interval;
Generating a frame including the STF and the LTF; And
And transmitting the frame.

The method of claim 10,
Wherein a polarity of an arbitrary repetition pattern area among four repetition pattern areas included in an effective symbol interval of the STF is set differently according to a transmission mode of the frame.

The method of claim 10,
Wherein a sequence element is allocated to odd-numbered or even-numbered subcarriers of each repetition pattern area included in an effective symbol interval of the STF.

The method of claim 10,
Base sequence elements are assigned to odd subcarriers among the repeated pattern regions included in the LTF valid symbol interval, and base sequence elements are allocated to even-numbered subcarriers among the repeated pattern areas included in the valid symbol period of the LTF Is assigned to the transformed sequence element.

The method of claim 10,
Wherein a base sequence element is allocated to a subcarrier included in an upper frequency band among the repeated pattern regions included in the LTF valid symbol period and a subsequence of subcarriers included in a lower frequency band among the repeated pattern regions included in an effective symbol interval of the LTF, And a transformed sequence element generated based on the base sequence element is assigned.

A signal transmission method performed in a terminal,
Generating a short training field (STF) composed of four repetitive pattern areas included in one CP (cyclic prefix) and an effective symbol section;
Generating a long training field (LTF) composed of one CP and one repetition pattern area included in the valid symbol interval;
Generating a collision detection field (CDF) comprising a single CP and a valid symbol interval including information indicating the terminal transmitting the frame;
Generating the frame including the STF, the LTF, and the CDF; And
And transmitting the frame.

16. The method of claim 15,
Wherein a sequence element is allocated to odd-numbered or even-numbered subcarriers of each repetition pattern area included in an effective symbol interval of the STF.

16. The method of claim 15,
Base sequence elements are assigned to odd subcarriers among the repeated pattern regions included in the LTF valid symbol interval, and base sequence elements are allocated to even-numbered subcarriers among the repeated pattern areas included in the valid symbol period of the LTF Is assigned to the transformed sequence element.

16. The method of claim 15,
Wherein a base sequence element is allocated to a subcarrier included in an upper frequency band among the repeated pattern regions included in the LTF valid symbol period and a subsequence of subcarriers included in a lower frequency band among the repeated pattern regions included in an effective symbol interval of the LTF, And a transformed sequence element generated based on the base sequence element is assigned.

16. The method of claim 15,
Wherein information indicating the terminal transmitting the frame is allocated to a subcarrier preset for each terminal in the valid symbol interval of the CDF.

The method of claim 19,
Wherein the information indicating the terminal transmitting the frame is a busy tone of the physical layer.