KR102289948B1 - Method and apparatus for transmitting and receiving information in wireless distributed system - Google Patents

Abstract

When the transmitter intends to transmit a first TOID among a plurality of Timing Offset Indication iDentifiers (TOIDs) indicating a timing offset of a frame, a first TOID corresponding to the first TOID among a plurality of codewords indicating a subcarrier 1 Determine the codeword. The transmitter allocates a busy tone to a first subcarrier indicated by the first codeword. And the transmitter transmits the busy tone.

Description

Method and apparatus for transmitting and receiving information in a wireless distributed system

The present invention relates to a method and apparatus for transmitting and receiving information.

In a conventional WLAN (Wireless Local Area Network) system, an access point (AP) centrally provides a contention-based time resource area to the terminal together with beacon start timing information (synchronization method). . In addition, in the conventional WLAN system, the terminal can know the service information (ie, discovery information) provided by the AP only through association with the AP.

In the conventional WLAN system, since the AP provides beacon start timing information, for power saving, in particular, the terminal in the sleep mode detects whether there is anyone looking for it, during a predetermined time period. only listen It can be said that there is a power saving effect through this, but since all terminals must go through an association process with an AP in order to know discovery information, system efficiency may be reduced due to power wastage and the like. For example, when the system associated with the first terminal does not provide the service desired by the first terminal, battery waste and time waste occur in the first terminal, and the system provides the service desired by the second terminal In the case of providing, the first terminal may have a bad influence on the association process of the second terminal, and thus system efficiency may be reduced.

An object of the present invention is to provide a physical layer signal carrying network synchronization information, contention window size information, and collision detection information. Specifically, an object of the present invention is to provide a physical layer signal carrying network synchronization information, contention window size information, and collision detection information in a wireless distributed system environment.

In addition, the problem to be solved by the present invention is a method in which a receiving node efficiently recognizes a message in terms of energy using orthogonality of a physical layer signal in a distributed node system employing a message-based distributed synchronization method, and this method It is to provide a transmission frame structure to which is applied.

According to an embodiment of the present invention, a transmission method of a transmitter is provided. The transmission method corresponds to the first TOID among a plurality of codewords indicating a subcarrier when a first TOID among a plurality of Timing Offset Indication iDentifiers (TOID) indicating a timing offset of a frame is to be transmitted. determining a first codeword to allocating a busy tone to a first subcarrier indicated by the first codeword; and transmitting the busy tone.

The transmission method may further include transmitting a preamble, which is a timing reference signal, in order to form synchronization of the frame in a network in which no infrastructure exists.

The transmitter may be a terminal different from an access point (AP).

The number of the first subcarriers indicated by the first codeword may be one.

The transmitting of the busy tone may include allocating all or part of the maximum power for one time domain symbol to the busy tone.

Allocating the busy tones may include allocating the busy tones to N first subcarriers represented by N elements (where N is a natural number greater than or equal to 2) included in the first codeword. can

M subcarriers (where M is a natural number equal to or greater than 2) may be grouped into N subcarrier groups.

Each of the N first subcarriers may belong to each of the N subcarrier groups.

A hamming distance between the first codeword and the remaining codewords among the plurality of codewords may be two or more.

The transmitting of the busy tones may include allocating 1/N of a maximum power for one time domain symbol to each of the busy tones allocated to the N first subcarriers.

At least one of the N subcarrier groups may correspond to a first time-domain symbol, and at least one may correspond to a second time-domain symbol.

The synchronization slot included in the frame is located before the preamble and includes: a nulling period for reducing signal collision; the preamble; a Timing Offset Indication Field (TOIF) located after the preamble and configured to provide a timing offset of the frame; and a Contention-Window Indication Field (CWIF) positioned after the preamble and configured to provide a size of a contention window.

Further, according to another embodiment of the present invention, a method of transmitting a transmitter is provided. In the transmission method, when a first CWID among a plurality of Contention Window Indication iDentifiers (CWID) indicating a contention window size is to be transmitted, the first CWID corresponding to the first CWID among a plurality of codewords indicating a subcarrier is transmitted. determining a first codeword; allocating a busy tone to a first subcarrier indicated by the first codeword; and transmitting the busy tone.

Allocating the busy tones may include allocating the busy tones to N first subcarriers represented by N elements (where N is a natural number) included in the first codeword. .

M subcarriers (where M is a natural number equal to or greater than 2) may be grouped into N subcarrier groups.

Each of the N first subcarriers may belong to each of the N subcarrier groups.

When N is 2 or more, a hamming distance between the first codeword and the remaining codewords among the plurality of codewords may be 2 or more.

The transmitting of the busy tones includes, when the N is 2 or more, allocating 1/N of the maximum power for one time domain symbol to each of the busy tones allocated to the N first subcarriers. may include

Further, according to another embodiment of the present invention, a method of transmitting a transmitter is provided. The transmission method may include, when transmitting first information having a first value, determining a first sequence corresponding to the first value from among a plurality of sequences indicating a value of the first information; allocating the first sequence to a plurality of usable subcarriers; and allocating power to the plurality of subcarriers.

The first information may be one of timing offset information of the frame, contention window size information of the transmitter, and collision detection information.

The allocating power to the plurality of subcarriers may include: dividing a maximum power for one time domain symbol by the number of the plurality of subcarriers; and allocating the divided power to each of the plurality of subcarriers.

Allocating the first sequence to the plurality of subcarriers may include assigning each element of the first sequence having a length corresponding to the number of the plurality of subcarriers to the plurality of subcarriers when the first sequence is one. It may include the step of assigning to each.

The determining of the first sequence may include: determining a first codeword corresponding to the first value among a plurality of codewords; and determining N first sequences corresponding to the first codeword among the plurality of sequences (where N is a natural number equal to or greater than 2).

The step of allocating the first sequence to the plurality of subcarriers includes: When the number of the plurality of available subcarriers is M (where M is a natural number equal to or greater than 2), each of the first sequences having a length of M/N The method may include allocating each element belonging to each of the M subcarriers.

Allocating each element of the first sequence to the M subcarriers may include allocating one of the two first sequences to an odd-numbered subcarrier among the M subcarriers when N is 2, and allocating the remainder of the two first sequences to an even-numbered subcarrier among subcarriers.

Allocating each element of the first sequence to the M subcarriers may include, when N is 4, allocating a second sequence among the four first sequences to a first subcarrier group among the M subcarriers; allocating a third sequence of the four first sequences to a second subcarrier group among the M subcarriers, and allocating a fourth sequence of the four first sequences to a third subcarrier group among the M subcarriers, and the M and allocating a fifth sequence among the four first sequences to a fourth subcarrier group among subcarriers.

The third sequence may be a modified sequence based on the second sequence.

The fifth sequence may be a modified sequence based on the fourth sequence.

According to an embodiment of the present invention, in a distributed node system employing a distributed synchronization method based on collision avoidance, through a timing offset indicator field and a contention window size indicator field designed under the time domain structure of a synchronization slot included in a frame , the receiving terminal may acquire timing offset information and contention window size information of other terminals with low power.

In addition, according to an embodiment of the present invention, network synchronization is possible even within a distributed node network, and communication between terminals can be implemented with low power.

1 is a diagram illustrating a frame structure for a distributed node system according to an embodiment of the present invention.
2 is a diagram illustrating a method of carrying timing offset information based on a tone.
3 is a diagram illustrating a method of carrying timing offset information based on a sequence.
4 is a diagram illustrating a method of carrying timing offset information based on a tone when two symbols are used.
5 is a diagram showing the configuration of a terminal according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, a terminal is a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR-MS) ), a subscriber station (subscriber station, SS), a portable subscriber station (PSS), an access terminal (AT), user equipment (UE), etc., and may refer to a terminal, MT, It may include all or some functions of MS, AMS, HR-MS, SS, PSS, AT, UE, and the like.

In addition, the access point (access point, AP), a base station (base station, BS), an advanced base station (advanced base station, ABS), a high reliability base station (high reliability base station, HR-BS), Node B (node B) ), advanced node B (eNodeB), radio access station (RAS), base transceiver station (BTS), MMR (mobile multihop relay)-BS, a repeater serving as a base station ( relay station, RS), a high reliability relay station (HR-RS) serving as a base station, may refer to a macro base station, a small base station, etc., and may refer to AP, BS, ABS, HR-BS, Node B, It may include all or part of the functions of eNodeB, RAS, BTS, MMR-BS, RS, HR-RS, macro base station, small base station, and the like.

Unlike the WLAN system, in a distributed node system, in order to increase system efficiency, the terminal acquires discovery information before association, and in order to reduce power consumption, a discovery timeslot exists separately, and the terminal in the sleep mode performs discovery Check only the timeslot. When such a distributed node system adopts a synchronization method, the terminal in the sleep mode can reduce power consumption. That is, if all terminals in the network know the boundary of a frame (eg, beacon) that is repeated in the time domain, and know the internal slot structure (eg, synchronization slot, discovery slot, data slot, etc.) included in the frame, the terminal Based on the frame boundary, it operates in the transmit mode, the receive mode, or the transmit/receive mode only in a specific slot (eg, a discovery slot when the terminal is in the sleep mode) within the interval, and maintains an inactive state in the remaining slots. can Through this, the terminal can reduce power consumption.

However, in the distributed node system, unlike the WLAN system, since there is no AP that provides frame synchronization, a distributed synchronization method in which terminals in the network participate in the transmission of synchronization signals to form frame synchronization in the network is used. . That is, in an environment in which no infrastructure exists, UEs may transmit a preamble that is a timing reference signal in order to form frame synchronization by themselves.

The distributed synchronization method includes a physical layer distributed synchronization method and a MAC (Medium Access Control)-based distributed synchronization method.

In the physical layer distributed synchronization method, when terminals in a network transmit and receive a specially designed synchronization signal located at the beginning of a frame, synchronization between terminals is matched using the time when the synchronization signal is received. Synchronization signals used in the physical layer distributed synchronization method include a pulse signal, a chirp signal, and a modulated Zadoff-Chu (ZC) signal. Basically, all terminals use the same synchronization signal. The terminal in the reception mode estimates the time timings of synchronization signals sent by a plurality of terminals and performs a process of taking an average between timings received from a plurality of transmitting terminals in certain frame intervals. Through this, frame boundary synchronization within the network may be matched.

However, in the physical layer distributed synchronization method, since the receiving terminal does not know how many terminals transmit the simultaneously received synchronization signal, the received signal may be out of the automatic gain control range of the receiving terminal, and thus the operation of the terminal There is a problem that this may not be done. Even if the received signal does not deviate from the automatic gain control range, since a plurality of synchronization signals having different received powers are mixed, if the received signal level is not expressed in a very fine digital signal, correlation estimation performance may be deteriorated. Due to this, the operation of the terminal may not be performed. To prevent this, an analog-to-digital converter (ADC) having a very high bit resolution may be used.

Meanwhile, the MAC-based distributed synchronization method is a method in which additional information related to synchronization is transmitted together when the terminal transmits a synchronization signal. For example, the terminal transmits timing offset information together with the synchronization signal in the form of a message, and the terminal that receives the synchronization signal uses the time at which the synchronization signal is received and the timing offset value received in the form of a message to create a frame motivate In the MAC-based distributed synchronization method, as in the physical layer distributed synchronization method, most terminals do not participate in distributed synchronization to transmit a synchronization signal, but only one terminal or some terminals transmits a synchronization signal. In the MAC-based distributed synchronization method, a terminal to transmit a synchronization signal may be determined using a back-off algorithm of WLAN. That is, each terminal sets a backoff counter value to a value randomly selected within its contention window (CW), and transmits a synchronization signal when the backoff counter becomes zero. Through this, it is possible to reduce the probability of a synchronization signal collision occurring when the synchronization signals are simultaneously transmitted. In the MAC-based distributed synchronization method, the receiving terminal performs correlation using the sequence correlation characteristic of the synchronization signal to determine the timing, and then needs to perform channel decoding to know the timing offset information. However, in a distributed node system, since the UEs have to evenly share the synchronization signal transmission role, it may not be suitable for the UE to perform channel decoding, which consumes much more power compared to performing correlation. Also, when different timing offset information collides with each other in a time interval containing timing offset information, the terminal cannot demodulate the two offset information. When the offset information collides as described above, if the receiving terminal can acquire two offset information, a collision between terminals having different distributed network synchronizations can be detected at the physical layer level, and this detection information is transmitted between the two networks. It can help with linking.

In a distributed node system employing a message-based distributed synchronization method (that is, a MAC-based distributed synchronization method), a method for carrying timing offset information is largely a tone-based method (hereinafter referred to as a 'tone-based method'). ) and a method based on a sequence (hereinafter referred to as a 'sequence-based method'). A tone-based scheme and a sequence-based scheme will be described in detail with reference to FIGS. 1 to 4 .

1 is a diagram illustrating a frame structure for a distributed node system according to an embodiment of the present invention.

One frame having a frame time duration (Tf1) includes a sync slot and other slots located after the sync slot and necessary for communication. For example, a synchronization slot, a discovery slot, a data slot, etc. may exist in the frame time period Tf1.

An arbitrary terminal transmits a synchronization signal for providing frame start timing in a synchronization slot. Here, the synchronization signal may be a signal having terminal commonality (ie, perfect correlation between synchronization signals of terminals), or may be a signal having terminal independence (ie, non-correlation between synchronization signals of terminals). As illustrated in FIG. 1 , a field other than a preamble for transmission of a synchronization signal may exist in the synchronization slot. The specific time domain structure/format (SSF1 to SSF4) of the sync slot illustrated in FIG. 1 will be described in detail. The first to fourth time-domain structures SSF1 to SSF4 of the sync slot have a difference in terms of field positions.

The first time domain structure SSF1 of the sync slot has a nulling interval F1a, a preamble F1b located after the nulling interval F1a, and a timing offset indicator field located after the preamble F1b (F1b). TOIF: Timing-Offset Indication Field, F1c), a Collision Detection Field (CDF: Collision Detection Field, F1d) located after TOIF (F1c), and a contention window indicator field (CWIF, Contention) located after CDF (F1d) -Window Indication Field, F1e). The nulling period F1a is a period for reducing the collision probability between signals of terminals to provide a timing reference, is located in front of the synchronization signal (ie, the preamble F1b), and slots having a predetermined interval like _{t S (} Yes, backoff slots). A synchronization signal for providing timing is provided through the preamble F1b. TOIF (F1c) carries the timing offset information of the frame. Although not illustrated in FIG. 1 , there may be a single guard interval or multiple guard intervals having a predetermined interval after CWIF (F1e). Also, although not illustrated in FIG. 1 , backoff slots may exist after CWIF (F1e). Moreover, the time length from the preamble (F1b) to the CWIF (F1e) cannot exceed the time length of one backoff slot.

The second time domain structure (SSF2) of the sync slot has a nulling period (F2a), a preamble (F2b) positioned after the nulling period (F2a), and CWIF (F2c) and CWIF (F2c) positioned after the preamble (F2b) CDF (F2d) positioned after, and TOIF (F2e) positioned after CDF (F2d). Although not illustrated in FIG. 1 , there may be a single guard interval or multiple guard intervals having a predetermined interval after TOIF (F2e). Also, although not illustrated in FIG. 1 , there may be backoff slots after TOIF (F2e). Moreover, the time length from the preamble (F2b) to the TOIF (F2e) cannot exceed the time length of one backoff slot.

The third time domain structure (SSF3) of the sync slot has a nulling period (F3a), a preamble (F3b) positioned after the nulling period (F3a), a preamble (F3b), a TOIF (F3c), and a TOIF (F3c) after the TOIF (F3c). CWIF (F3d) positioned after, and CDF (F3e) positioned after CWIF (F3d). Although not illustrated in FIG. 1 , there may be a single guard interval or multiple guard intervals having a predetermined interval after the CDF (F3e). Also, although not illustrated in FIG. 1 , there may be backoff slots after CDF (F3e). Moreover, the time length from the preamble (F3b) to the CDF (F3e) cannot exceed the time length of one backoff slot.

The fourth time domain structure (SSF4) of the sync slot is after the nulling period (F4a), the preamble (F4b) positioned after the nulling period (F4a), the preamble (F4b), after the CWIF (F4c), and after the CWIF (F4c) TOIF (F4d) positioned after, and CDF (F4e) positioned after TOIF (F4d). Although not illustrated in FIG. 1 , there may be a single guard interval or multiple guard intervals having a predetermined interval after the CDF (F4e). Also, although not illustrated in FIG. 1 , backoff slots may exist after CDF (F4e). Moreover, the time length from the preamble (F4b) to the CDF (F4e) cannot exceed the time length of one backoff slot.

The purpose of CWIF (F1e, F2c, F3d, F4c) is for a specific terminal to broadcast its contention window size information to neighboring terminals.

The purpose of the CDF (F1d, F2d, F3e, F4e) is to detect collisions generated by a plurality of terminals in the physical layer.

The purpose of the TOIF (F1c, F2e, F3c, F4d) is to provide a specific UE with timing offset information of a frame to which the TOIF field (F1c, F2e, F3c, F4d) belongs to neighboring UEs. As a specific example, the timing offset of the TOIF fields F1c, F2e, F3c, and F4d existing within the frame time period Tf1 of FIG. 1 is the start point of the frame time period Tf1 and the preambles F1b, F2b, F3b, F4b. is the time difference between the starting points of As a method of representing the time difference, there may be a method of representing an actual physical time difference, a method of representing an integer number of backoff slots, and the like. That is, in order to synchronize the last time of every frame (frame boundary), a timing offset concept may be introduced.

Meanwhile, the timing offset information may be transmitted using the orthogonality of the physical layer sequence (sequence-based method), or may be transmitted using orthogonal tones of the physical layer (eg, subcarriers in the frequency domain) (tone-based method) , or may be transmitted in the form of a message. Specifically, the sequence-based method maps specific timing offset information to a specific sequence having orthogonality. The tone-based method maps timing offset information to a single tone (eg, subcarrier) or a combination of multiple tones in the frequency domain. In the method of transmitting the timing offset information in the form of a message, the terminal transmits the timing offset information in the message, and the terminal that receives it restores the message through channel decoding. Since the terminal may consume excessive power by performing channel decoding, an embodiment of the present invention will be described focusing on the tone-based method and the sequence-based method.

Hereinafter, for convenience of description, a tone-based scheme and a sequence-based scheme will be described using the first time domain structure SSF1 of the sync slot as an example. However, this is only an example, and the tone-based scheme and the sequence-based scheme can be applied to other time domain structures (SSF2 to SSF4) of the sync slot.

2 is a diagram illustrating a method (ie, a tone-based method) for carrying timing offset information based on a tone. Specifically, FIG. 2 shows three methods of transporting timing offset information based on a tone (eg, subcarrier) through TOIF (F1c) in a distributed node system employing a collision avoidance-based distributed synchronization method as in FIG. 1 ( a first tone-based method, a second tone-based method, and a third tone-based method).

The first tone-based scheme is illustrated in the frequency domain TSUB1 for TOIF F1c in FIG. 2 . In the first tone-based scheme, available tones, ie, positions of available subcarriers, are mapped one-to-one to a Timing Offset Indication iDentifier (TOID). According to the first tone-based scheme, the total number of distinguishable TOIDs becomes the total number of usable subcarriers (N). In FIG. 2 , for convenience of explanation, a case in which the number N of all available subcarriers SC_0 to SC_15 is 16 is exemplified. The positions of each of the 16 subcarriers (SC_0 to SC_15) are mapped to each of the 16 TOIDs (TO_0 to TO_15). For example, the position of the subcarrier SC_0 may be mapped to TOID(TO_0), and the position of the subcarrier SC_1 may be mapped to TOID(TO_1). Each TOID (TO_0 to TO_15) represents a timing offset value. For example, TOID(TO_0) may indicate timing offset 0 t _S , and TOID(TO_1) may indicate _{timing offset 1 t S .} Specifically, the terminal determines the position of the subcarrier corresponding to the timing offset to be transmitted, allocates a busy tone to the determined position of the subcarrier (carry), and applies power to the busy tone to provide the busy tone. to send For example, if the terminal is in the timing offset t 8 _S to be transmitted, the MS allocates a busy tone to the position of the sub-carriers (SC_8) corresponding to TOID (TO_8) represents the 8 _S t. And the UE loads (allocates) all or part of the maximum power that can be transmitted per one time domain symbol (hereinafter, 'symbol maximum power') to the busy tone allocated to the position of the subcarrier (SC_8), and transmits the busy tone do.

The second tone-based scheme is illustrated in the frequency domain TSUB2 for TOIF F1c in FIG. 2 . In the second tone-based scheme, one TOID is mapped to the positions of two subcarriers. Specifically, one TOID is mapped to one codeword (Z, Y). Here, one codeword (Z, Y) represents two subcarriers. According to the second tone-based scheme, the total number of codewords becomes the square of half of the total number of usable subcarriers (N). For example, when N is 16, the total number of codewords is 64. Here, Z, which is an element of the codeword (Z, Y), has a positive integer value (0-7) ranging from 0 to (N/2)-1, and represents a subcarrier group. Specifically, Z represents the position index of available upper (or lower) subcarriers (SC_0 to SC_7). Y, which is an element of the codeword (Z, Y), has a positive integer value from 0 to (N/2)-1 (eg, 0 to 7) and represents a subcarrier group. Specifically, Y indicates the position index of the available lower (or higher) subcarriers (SC_8 to SC_15). For example, codeword (0, 0) may be mapped to TOID(TO_0), and codeword (1, 1) may be mapped to TOID(TO_1). Each TOID represents a timing offset value. On the other hand, when the total number of TOIDs is smaller than the total number of codewords, a codeword to be mapped to the TOID is selected from among all codewords. Specifically, codewords in which a Hamming distance between codewords is at most 1 may be selected. That is, there must be no element having the same value (eg, 0 to 7) between the codeword and the codeword, or there must be only one element having the same value. For example, there is no element with the same value between codeword (0, 1) and codeword (1, 0). That is, the Hamming distance between codewords is 0. As another example, there is one element having the same value between the codeword (2, 5) and the codeword (2, 3). That is, the Hamming distance between codewords is 1.

Specifically, the terminal determines the positions of two subcarriers corresponding to the timing offset to be transmitted. For example, when a timing offset that the mobile station wants to send an 8 t _S, the terminal code word (z, y) (for example, codes corresponding to TOID (e.g., TO_8) represents the 8 t _S word (0, 1)), and the positions of two subcarriers (eg, SC_0, SC_9) corresponding to the codeword (z, y) (eg, codeword (0, 1)) are determined. In addition, the UE allocates (carry) busy tones to the determined positions of the two subcarriers (eg, SC_0 and SC_9), and transmits the busy tones by applying power to the busy tones. Specifically, the UE may load half or less of the maximum symbol power on each of the busy tones allocated to the positions of the two subcarriers (eg, SC_0 and SC_9).

On the other hand, the element Z of the codeword (Z, Y) indicates the position index of the available lower subcarriers (SC_8 ~ SC_15), and the element Y of the codeword (Z, Y) is the position of the available upper subcarriers (SC_0 ~ SC_7) It can also indicate an index.

The third tone-based scheme is illustrated in the frequency domain TSUB3 for TOIF F1c in FIG. 2 . In the third tone-based scheme, one TOID is mapped to positions of four subcarriers. Specifically, one TOID is mapped to one codeword (Z, Y, X, W). Here, one codeword (Z, Y, X, W) represents four subcarriers, and each TOID represents a timing offset value. According to the third tone-based scheme, the total number of codewords becomes the fourth power of the number (N) of the total number of usable subcarriers. For example, when N is 16, the total number of codewords is 256. Here, Z, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (N/4)-1 (eg, 0 to 3) and represents a subcarrier group. Specifically, Z represents the position index of some upper (or lower) subcarriers SC_0 to SC_3 among the available upper (or lower) subcarriers SC_0 to SC_7. Y, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (N/4)-1 (eg, 0 to 3) and represents a subcarrier group. Specifically, Y indicates the position index of some lower (or higher) subcarriers SC_4 to SC_7 among the available upper (or lower) subcarriers SC_0 to SC_7. X, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (N/4)-1 (eg, 0 to 3) and represents a subcarrier group. Specifically, X represents the position index of some upper (or lower) subcarriers SC_8 to SC_11 among available lower (or higher) subcarriers SC_8 to SC_15. W, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (N/4)-1 (eg, 0 to 3) and represents a subcarrier group. Specifically, W indicates the position index of some lower (or higher) subcarriers SC_12 to SC_15 among the available lower (or higher) subcarriers SC_8 to SC_15. For example, codeword (0, 0, 0, 0) is _{mapped to TOID (eg TO_0) representing timing offset 0 t S} , and codeword (1, 1, 1, 1) is timing offset 1 t _S may be mapped to TOID (eg, TO_1) representing On the other hand, when the total number of TOIDs is smaller than the total number of codewords, a codeword to be mapped to the TOID among all codewords is selected. Specifically, codewords having a Hamming distance of at least 2 between codewords may be selected. That is, there must be no element having the same value (eg, 0 to 3) between the codeword and the codeword, there must be only one element having the same value, or there must be only two elements having the same value. For example, there is no element having the same value between the codeword (1, 0, 0, 0) and the codeword (0, 1, 1, 2). For another example, two elements having the same value exist between the codeword (0, 1, 1, 3) and the codeword (2, 1, 0, 3).

Specifically, the terminal determines the positions of four subcarriers corresponding to the timing offset to be transmitted. For example, when a timing offset that the mobile station wants to send a 6 t _S, and determines the terminal code word (z, y, x, w) corresponding to TOID (for example, TO_6) represents the 6 t _S, The positions of four subcarriers corresponding to the determined codeword (z, y, x, w) are determined. Then, the UE allocates busy tones to the determined positions of the four subcarriers (carry), and transmits the busy tones by applying power to each busy tone. Specifically, the UE may load a quarter or less of the maximum symbol power on each of the busy tones allocated to the positions of the four subcarriers.

Meanwhile, the subcarrier group represented by each element of the codeword (Z, Y, X, W) may be designed differently from the above. For example, Z represents the location index of some subcarriers (SC_8~SC_11) among the available lower subcarriers (SC_8~SC_15), Y represents the location index of the remaining subcarriers (SC_12~SC_15), X represents the available upper subcarriers Among (SC_0 to SC_7), position indexes of some subcarriers SC_4 to SC_7 may be indicated, and W may indicate position indexes of the remaining subcarriers SC_0 to SC_3.

3 is a diagram illustrating a method (ie, a sequence-based method) for carrying timing offset information based on a sequence. Specifically, FIG. 3 shows five methods (first sequence-based method) for carrying timing offset information through TOIF (F1c) based on a sequence in a distributed node system employing a collision avoidance-based distributed synchronization method as in FIG. 1 . , a second sequence-based scheme, a third sequence-based scheme, a fourth sequence-based scheme, and a fifth sequence-based scheme). 3 exemplifies a case in which the total number of usable subcarriers is 16 for convenience of explanation.

The first sequence-based scheme is illustrated in the frequency domain SSUB1 for the TOIF F1c in FIG. 3 . In the first sequence-based scheme, the index of the sequence is mapped to the TOID. That is, the sequence and TOID are mapped one-to-one. Each TOID represents a timing offset value. For example, TOID(TO_8) may indicate a _{timing offset 8t S .} According to the first sequence-based scheme, the number of distinguishable total TOIDs becomes an index of all available sequences, that is, the number (L) of all available sequences. Specifically, the terminal determines the index of the sequence corresponding to the timing offset to be transmitted, allocates the determined sequence to usable subcarriers, and applies power to the subcarriers to which the sequence is allocated. For example, when the timing offset to be transmitted by the terminal is 8 t _S , the terminal applies a sequence having an index of 8 among L sequences (that is, a sequence corresponding to TOID(TO_8)) to all available subcarriers. allocate In the area SSUB1 of FIG. 3, the case where the length of the sequence is 16 is exemplified. Specifically, when the total number of usable subcarriers is 16, the UE may allocate each of 16 elements belonging to a sequence having an index of 8 to each of the 16 subcarriers. And, the UE divides all or part of the maximum symbol power equally by the total number of usable subcarriers (16) and loads (allocates) them to each of the 16 subcarriers. In addition, the UE transmits a sequence (a sequence corresponding to a _{timing offset of 8t S) allocated to 16 subcarriers. Meanwhile, b Z} (i) illustrated in the region SSUB1 of FIG. 3 represents the i-th element belonging to the Z (having a positive integer value from 0 to L-1)-th sequence. In the region SSUB1 of FIG. 3 , a case in which each of 16 elements b _Z (0) to b _Z (15) belonging to one sequence is allocated to each of 16 subcarriers is exemplified. The _{sequence constituted by b Z} (i) is a base sequence.

The second sequence-based scheme is illustrated in the frequency domain SSUB2 for the TOIF F1c in FIG. 3 . In the second sequence-based scheme, one TOID is mapped to indices of two sequences. Specifically, one TOID is mapped to one codeword (Z, Y). That is, one codeword (Z, Y) represents a sequence of index Z and a sequence of index Y. According to the second sequence-based scheme, the total number of codewords becomes the square of half the number of usable total sequences (L, eg, L = the number of sequences for index Z + the number of sequences for index Y). For example, when L is 16, the total number of codewords is 64. Here, Z, which is an element of the codeword (Z, Y), has a positive integer value from 0 to (L/2)-1 (or a value greater than (L/2)-1) and represents a sequence. . Specifically, Z represents an index of a sequence composed of elements allocated to positions of available even (or odd) subcarriers. For example, in the region SSUB2 of FIG. 3 , the length of the sequence of index Z is 8, and each of 8 elements (b _Z (0) to b _Z (7)) belonging to the sequence of index Z is 8 even numbers. A case in which each of the subcarriers is allocated has been exemplified. Y, which is an element of the codeword (Z, Y), has a positive integer value from 0 to (L/2)-1, and represents a sequence. Specifically, Y represents an index of a sequence composed of elements allocated to positions of available odd (or even) subcarriers. For example, in the region SSUB2 of FIG. 3 , the length of the sequence of index Y is 8, and each of the 8 elements (m _Y (0) to m _Y (7)) belonging to the sequence of index Y is 8 odd numbers. A case in which each of the subcarriers is allocated has been exemplified. That is, in the region SSUB2 of FIG. 3 , the case where the length of the sequence of index Z and the sequence of index Y is half of the total number of usable subcarriers (eg, 16) is exemplified. For example, when the timing offset to be transmitted by the terminal is 8 t _S , the terminal determines two sequences corresponding to TOID (TO_8) from among L sequences. _{And the UE allocates each element ((b Z} (0) to b _Z (7)) belonging to one of the two determined sequences to 8 even subcarriers among 16 subcarriers, and among the two sequences Each of the elements (m _Y (0) to m _Y (7)) belonging to the remaining sequence is allocated to 8 odd subcarriers out of 16 subcarriers, and the UE uses all or part of the maximum symbol power It can be divided equally by the number of subcarriers (16), and can be assigned (allocated) to each of the 16 subcarriers, and the UE has two sequences allocated to the 16 subcarriers (two sequences corresponding to the _{timing offset 8t S )} to send

Meanwhile, the ranges of Z and Y may be different from each other. For example, Z may have a positive integer value from 0 to (L/2)+1, and Y may have a positive integer value from 0 to (L/2)-3.

On the other hand, the element Z of the codeword (Z, Y) indicates the index of a sequence consisting of elements allocated to the positions of the available odd subcarriers, and the element Y of the codeword (Z, Y) is the position of the available even subcarriers. It may indicate an index of a sequence consisting of elements assigned to .

Meanwhile, a sequence applied to index Z and a sequence applied to index Y may be identical to each other. Alternatively, the sequence applied to the index Z and the sequence applied to the index Y may be completely different types of sequences. Alternatively, the sequence applied to the index Z and the sequence applied to the index Y may have the same sequence itself, but one of them may be a base sequence and the other may be a modified sequence modified based on the base sequence. The correction sequence will be specifically described. When the total number of TOIDs is smaller than the total number of codewords, a codeword to be mapped to the TOID among all codewords is selected. Specifically, codewords having a hamming distance between codewords at most 1 may be selected. That is, there must be no element having the same value (eg, 0 to (L/2)-1) between the codeword and the codeword, or there must be only one element having the same value. In region SSUB2 of FIG. 3 , the sequence applied to index Y is a modified sequence (corresponding to m(.) in FIG. 3) of the base sequence (corresponding to b(.) in FIG. 3) applied to index Z. case was exemplified. For example, a modified sequence uses the base sequence as is, reverses the polarity (multiplying element values of the base sequence by -1), or conjugating (conjugating the element values of the base sequence, i.e., an imaginary number). reverse polarity), or by conjugating and reversing the polarity. The reason why the correction sequence is used is to lower the PAPR (Peak to Average Power Ratio) of the time domain signal of the TOIF subslot. When the same sequence, not the modified sequence, is used, the PAPR in the time domain becomes very high, and an expensive amplifier needs to be used in the implementation to prevent a performance decrease due to the high PAPR, which results in a disadvantage in that the terminal cost is increased. can

The third sequence-based scheme is illustrated in the frequency domain SSUB3 for the TOIF F1c in FIG. 3 . In the third sequence-based scheme, one TOID is mapped to indices of two sequences. Specifically, one TOID is mapped to one codeword (Z, Y). That is, one codeword (Z, Y) represents a sequence of index Z and a sequence of index Y. According to the third sequence-based scheme, the total number of codewords becomes the square of half the number (L) of the total available sequences. Here, Z, which is an element of the codeword (Z, Y), has a positive integer value from 0 to (L/2)-1 (or a value greater than (L/2)-1) and represents a sequence. . Specifically, Z represents an index of a sequence composed of elements allocated to positions of available upper (or lower) subcarriers. For example, in the region SSUB3 of FIG. 3 , the length of the sequence of index Z is 8, and each of the 8 elements (b _Z (0) to b _Z (7)) belonging to the sequence of index Z is 16 available. A case in which 8 subcarriers are allocated to each of 8 upper subcarriers is exemplified. Y, which is an element of the codeword (Z, Y), has a positive integer value from 0 to (L/2)-1, and represents a sequence. Specifically, Y indicates an index of a sequence composed of elements allocated to positions of available lower (or higher) subcarriers. For example, in the region SSUB3 of FIG. 3 , the length of the sequence of index Y is 8, and each of the 8 elements (m _Y (0) to m _Y (7)) belonging to the sequence of index Y is 16 usable. A case in which 8 subcarriers are allocated to each of 8 subcarriers is exemplified. That is, in the region SSUB3 of FIG. 3 , the case where the length of the sequence of index Z and the sequence of index Y is half of the total number of usable subcarriers (eg, 16) is exemplified. For example, when the timing offset to be transmitted by the terminal is 8 t _S , the terminal determines two sequences corresponding to TOID (TO_8) from among L sequences. _{And the UE allocates each element ((b Z} (0) to b _Z (7)) belonging to one of the two determined sequences to 8 higher subcarriers among 16 available subcarriers, and two _{Each element (m Y} (0) to m _Y (7)) belonging to one of the remaining sequences in the sequence is allocated to 8 lower subcarriers out of 16 available subcarriers, and the UE allocates all or part of the maximum symbol power is equally divided by the total number of usable subcarriers (16), and can be loaded (allocated) to each of the 16 subcarriers, and the UE can assign two sequences (timing offset 8t _{S ) assigned to the 16 subcarriers.} two sequences).

Meanwhile, the ranges of Z and Y may be different from each other. For example, Z may have a positive integer value from 0 to (L/2)+1, and Y may have a positive integer value from 0 to (L/2)-3.

On the other hand, the element Z of the codeword (Z, Y) indicates the index of a sequence consisting of elements allocated to the positions of the available lower subcarriers, and the element Y of the codeword (Z, Y) is the position of the available upper subcarriers. It may indicate an index of a sequence consisting of elements assigned to .

Meanwhile, a sequence applied to index Z and a sequence applied to index Y may be identical to each other. Alternatively, the sequence applied to the index Z and the sequence applied to the index Y may be completely different types of sequences. Alternatively, the sequence applied to the index Z and the sequence applied to the index Y may have the same sequence itself, but one of them may be a base sequence and the other may be a modified sequence modified based on the base sequence. If the total number of TOIDs is smaller than the total number of codewords, a TOID to be mapped to TOIDs among all codewords is selected. Specifically, codewords having a hamming distance between codewords at most 1 may be selected. That is, there must be no element having the same value (eg, 0 to (L/2)-1) between the codeword and the codeword, or there must be only one element having the same value. Meanwhile, a sequence applied to index Z and a sequence applied to index Y may be different from each other. Alternatively, as illustrated in the region SSUB3 of FIG. 3 , the sequence applied to index Y is a modified sequence (corresponding to m(.)) of the base sequence (corresponding to b(.)) applied to index Z. can Specifically, a modified sequence can be created by using the base sequence as is, by reversing the polarity, by conjugating, or by conjugating and inverting the polarity.

A fourth sequence-based scheme is illustrated in the frequency domain SSUB4 for TOIF F1c in FIG. 3 . In the fourth sequence-based scheme, one TOID is mapped to indices of four sequences. Specifically, one TOID is mapped to one codeword (Z, Y, X, W). That is, one codeword (Z, Y, X, W) represents a sequence of index Z, sequence of index Y, sequence of index X, and sequence of index W. According to the fourth sequence-based scheme, the total number of codewords is the number of available total sequences (L, eg, L = the number of sequences for index Z + the number of sequences for index Y + the number of sequences for index X + index W is the fourth power of the number of sequences for . For example, when L is 16, the total number of codewords is 256. Here, Z, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 (or a value greater than (L/4)-1) , represents the sequence. Specifically, Z represents an index of a sequence composed of elements allocated to positions of some upper (or lower) subcarriers among available upper (or lower) subcarriers. For example, in the region SSUB4 of FIG. 3 , the length of the sequence of index Z is 4, and each of the four elements (b _Z (0) to b _Z (3)) belonging to the sequence of index Z is 8 available. A case in which four upper subcarriers are allocated to each of the upper subcarriers is exemplified. Y, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 and represents a sequence. Specifically, Y represents an index of a sequence composed of elements allocated to positions of some lower (or higher) subcarriers among available upper (or lower) subcarriers. For example, in the region SSUB4 of FIG. 3 , the length of the sequence of index Y is 4, and each of the four elements (b _Y (0) to b _Y (3)) belonging to the sequence of index Y is 8 available. A case in which four lower subcarriers are allocated to each of the upper subcarriers is exemplified. X, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 and represents a sequence. Specifically, X represents an index of a sequence composed of elements allocated to positions of some upper (or lower) subcarriers among available lower (or higher) subcarriers. For example, in the region SSUB4 of FIG. 3 , the length of the sequence of index X is 4, and each of the four elements (m _X (0) to m _X (3)) belonging to the sequence of index X is 8 available. A case in which four lower subcarriers are allocated to each of four upper subcarriers is exemplified. W, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 and represents a sequence. Specifically, W represents an index of a sequence composed of elements allocated to positions of some lower (or higher) subcarriers among available lower (or higher) subcarriers. For example, in the region SSUB4 of FIG. 3 , the length of the sequence of index W is 4, and each of the four elements (m _W (0) to m _W (3)) belonging to the sequence of index W is 8 available. A case in which 4 subcarriers are allocated to each of 4 subcarriers is exemplified. That is, in the region SSUB4 of FIG. 3 , the length of the sequence of index Z, sequence of index Y, sequence of index X, and sequence of index W is a quarter of the total number of available subcarriers (eg, 16) 1 is exemplified. For example, when the timing offset to be transmitted by the terminal is 8 t _S , the terminal determines four sequences corresponding to TOID(TO_8) from among L sequences. _{And, the UE allocates each element ((b Z} (0) to b _Z (3)) belonging to one of the determined four sequences to four upper subcarriers among eight available upper subcarriers, 4 Each of the elements (b _Y (0) to b _Y (3)) belonging to another sequence among Each element belonging to the sequence (m _X (0) to m _X (3)) is assigned to 4 upper subcarriers out of 8 available lower subcarriers, and an element belonging to the other one of the 4 sequences ((m) _{Each of W} (0) ~ m _W (3)) is allocated to 4 subcarriers out of 8 available subcarriers, and the UE uses all or part of the maximum symbol power for the total number of usable subcarriers (16 ) to be divided equally, the chamber (D) assigned to the 16 sub-carriers, respectively, and the terminal transmits a sequence of four (4 sequence corresponding to the timing offset 8t _S) assigned to the 16 sub-carriers.

Meanwhile, the ranges of Z, Y, X, and W may be different from each other. For example, Z has positive integer values from 0 to (L/4)+1, Y has positive integer values from 0 to (L/4)-3, and X has positive integer values from 0 to (L It has a positive integer value from /4)-3, and W may have a positive integer value from 0 to (L/4)+1.

Meanwhile, sequences applied to index Z, index Y, index X, and index W may be identical to each other. Alternatively, the sequences applied to the index Z, the index Y, the index X, and the index W may be completely different types of sequences. Alternatively, the sequences applied to the index Z, the index Y, the index X, and the index W may be the same sequence itself, but a part may be a base sequence and another part may be a modified sequence modified based on the base sequence. If the total number of TOIDs is smaller than the total number of codewords, a codeword to be mapped to the TOID among all codewords is selected. Specifically, codewords having a hamming distance between codewords of at most 2 may be selected. That is, there must be no element with the same value (eg 0 to (L/4)-1) between the codeword and the codeword, there must be only one element with the same value, or there must be only two elements with the same value. do. On the other hand, in the region SSUB4 of FIG. 3 , the base sequence (corresponding to b(.)) is applied to the sequence of index Z and the sequence of index Y, and the modified sequence (m( .)) is applied as an example. For example, the sequence applied to index X may be a modified sequence (m _{x (.)) of the base sequence (b Z} (.)) applied to index Z, and the sequence applied to index W is, index Y It may be a modified sequence (m _W (.)) of the base sequence (b _{Y (.)) applied to .} Specifically, the modified sequence applied to the fourth sequence-based scheme may be generated by using the base sequence as it is, reversing the polarity, conjugating, or conjugating and inverting the polarity.

The fifth sequence-based scheme is exemplified in the frequency domain SSUB5 for the TOIF F1c in FIG. 3 . In the fifth sequence-based scheme, one TOID is mapped to indices of four sequences. Specifically, one TOID is mapped to one codeword (Z, Y, X, W). That is, one codeword (Z, Y, X, W) represents a sequence of index Z, sequence of index Y, sequence of index X, and sequence of index W. According to the fifth sequence-based scheme, the number of total codewords becomes the fourth power of the number (L) of the total available sequences. Here, Z, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 (or a value greater than (L/4)-1) , represents the sequence. Specifically, Z represents an index of a sequence composed of elements allocated to positions of some upper (or lower) subcarriers among available upper (or lower) subcarriers. For example, in the region SSUB5 of FIG. 3 , the length of the sequence of index Z is 4, and each of the four elements (b _Z (0) to b _Z (3)) belonging to the sequence of index Z is 8 available A case in which four upper subcarriers are allocated to each of the upper subcarriers is exemplified. Y, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 and represents a sequence. Specifically, Y indicates an index of a sequence composed of elements allocated to positions of some lower (or higher) subcarriers among available upper (or lower) subcarriers. For example, in the region SSUB5 of FIG. 3 , the length of the sequence of index Y is 4, and each of the four elements (m _Y (0) to m _Y (3)) belonging to the sequence of index Y is 8 available. A case in which four lower subcarriers are allocated to each of the upper subcarriers is exemplified. X, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 and represents a sequence. Specifically, X represents an index of a sequence composed of elements allocated to positions of some upper (or lower) subcarriers among available lower (or higher) subcarriers. For example, in the region SSUB5 of FIG. 3 , the length of the sequence of index X is 4, and each of the four elements (b _X (0) to b _X (3)) belonging to the sequence of index X is 8 available A case in which four lower subcarriers are allocated to each of four upper subcarriers is exemplified. W, which is an element of the codeword (Z, Y, X, W), has a positive integer value from 0 to (L/4)-1 and represents a sequence. Specifically, W represents an index of a sequence composed of elements allocated to positions of some lower (or higher) subcarriers among available lower (or higher) subcarriers. For example, in the region SSUB5 of FIG. 3 , the length of the sequence of index W is 4, and each of the four elements (m _W (0) to m _W (3)) belonging to the sequence of index W is 8 available. A case in which 4 subcarriers are allocated to each of 4 subcarriers is exemplified. That is, in the region SSUB5 of FIG. 3 , the length of the sequence of index Z, index Y, index X, and index W is a quarter of the total number of usable subcarriers (eg, 16). . For example, when the timing offset to be transmitted by the terminal is 8 t _S , the terminal determines four sequences corresponding to TOID(TO_8) from among L sequences. _{And, the UE allocates each element ((b Z} (0) to b _Z (3)) belonging to one of the determined four sequences to four upper subcarriers among eight available upper subcarriers, 4 Each of the elements (m _Y (0) to m _Y (3)) belonging to another sequence among Each element belonging to the sequence (b _X (0) to b _X (3)) is allocated to 4 upper subcarriers out of 8 available lower subcarriers, and an element belonging to the remaining one of the 4 sequences ((m) _{Each of W} (0) ~ m _W (3)) is allocated to 4 subcarriers out of 8 available subcarriers, and the UE uses all or part of the maximum symbol power to the number of available total subcarriers (16 ) to be divided equally, the chamber (D) assigned to the 16 sub-carriers, respectively, and the terminal transmits a sequence of four (4 sequence corresponding to the timing offset 8t _S) assigned to the 16 sub-carriers.

Meanwhile, the ranges of Z, Y, X, and W may be different from each other. For example, Z has positive integer values from 0 to (L/4)+1, Y has positive integer values from 0 to (L/4)-3, and X has positive integer values from 0 to (L It has a positive integer value from /4)-3, and W may have a positive integer value from 0 to (L/4)+1.

Meanwhile, sequences applied to index Z, index Y, index X, and index W may be identical to each other. Alternatively, the sequences applied to the index Z, the index Y, the index X, and the index W may be completely different types of sequences. Alternatively, the sequences applied to the index Z, the index Y, the index X, and the index W may be the same sequence itself, but a part may be a base sequence and another part may be a modified sequence modified based on the base sequence. If the total number of TOIDs is smaller than the total number of codewords, a codeword to be mapped to the TOID among all codewords is selected. Specifically, codewords having a hamming distance between codewords of at most 2 may be selected. That is, there must be no element with the same value (eg 0 to (L/4)-1) between the codeword and the codeword, there must be only one element with the same value, or there must be only two elements with the same value. do. On the other hand, in the region SSUB5 of FIG. 3 , the base sequence (corresponding to b(.)) is applied to the sequence of index Z and the sequence of index X, and the modified sequence (m ( .)) is applied as an example. For example, the sequence applied to the index Y may be a modified sequence (m _{Y (.)) of the base sequence (b Z} (.)) applied to the index Z, and the sequence applied to the index W is the index X It may be a modified sequence (m _W (.)) of the base sequence (b _{X (.)) applied to .} Specifically, the modified sequence applied to the fifth sequence-based scheme may be generated by using the base sequence as it is, reversing the polarity, conjugating, or conjugating and inverting the polarity.

The tone-based method and the sequence-based method for carrying the above-described timing offset information have advantages and disadvantages. Specifically, in the tone-based scheme, since the receiving terminal only needs to estimate a tone exceeding a threshold value within a corresponding subcarrier group, the reception operation of the receiving terminal is simple. In addition, in the tone-based method, since the transmitting terminal transmits power with only one or very few frequency domain tones (eg, subcarriers), PAPR in the time domain may be very low. For better understanding, when an impulse in the frequency domain is made into a time domain signal through Fourier transform, a signal with a flat magnitude is generated, so the PAPR for this signal is theoretically 0 dB. On the other hand, in the sequence-based scheme, the receiving terminal must perform correlation or dispreading on the corresponding subcarrier group, and PAPR may be slightly higher than that of the tone-based scheme. Accordingly, the tone-based scheme may be designed with low power compared to the sequence-based scheme in terms of implementation. On the other hand, in the tone-based method, a tone (eg, a subcarrier) loaded with power may fall into deep fading due to the characteristics of a wireless channel, and thus the TOID estimation performance of the receiving terminal may be deteriorated. On the other hand, in the sequence-based method, the transmitting terminal does not transmit power only to a specific subcarrier, but transmits equal power and sequence elements to all available subcarriers, so diversity gain and spreading gain can be obtained. . Therefore, the sequence-based scheme may be superior to the tone-based scheme in terms of TOID estimation performance. Therefore, one of a tone-based scheme and a sequence-based scheme may be selected depending on which direction is sought. Meanwhile, both the tone-based scheme and the sequence-based scheme can be designed with very low power compared to a message-type transmission scheme to which channel decoding must be applied.

Meanwhile, in FIGS. 2 and 3 , a case in which all available subcarrier resources are divided into up to four groups is exemplified. In addition, in FIGS. 2 and 3 , when all available subcarrier resources are divided into four groups, if the total number of TOIDs is less than the total number of codewords, the Hamming distance between codewords having a length of 4 is up to 2 It is exemplified that the codewords that become TOID are mapped to TOID. However, this is only an example. An embodiment of the present invention may be applied to a case in which all available subcarrier resources are divided into groups of up to Q (where Q is a natural number). In addition, when all available subcarrier resources are divided into Q groups, if the total number of TOIDs is less than the total number of codewords, codewords whose Hamming distance between codewords of length Q is at least 2 are included in the TOID. The mapped embodiment may also be included in the embodiment of the present invention.

Meanwhile, in FIGS. 2 and 3 , a case in which one time domain symbol is used is exemplified. This is just an example. If it is necessary to increase the total number of distinguishable TOIDs, the embodiments of FIGS. 2 and 3 can be extended. For example, if multiple (eg, M) adjacent (or non-adjacent) time-domain symbols are used, since the M symbols are orthogonal to each other in the time domain, the total number of TOIDs is equal to the number of times one time domain symbol is used. It can be increased up to P times compared to the case. Alternatively, if M time-domain symbols are used, the additional time-domain symbols are not used to increase the number of TOIDs, but may be used to increase the detection performance of TOIDs. Meanwhile, in the method using a plurality of symbols, the frequency domain TOID mapping applied to the first symbol among the plurality of symbols may be directly applied to the remaining symbols among the plurality of symbols. Alternatively, in a method using a plurality of symbols, various types of different TOID mappings may be applied to each of the plurality of symbols. A method of using a plurality of symbols will be described in detail with reference to FIG. 4 .

4 is a diagram illustrating a method (ie, a tone-based method) for carrying timing offset information based on a tone when two symbols are used. Specifically, in FIG. 4 , a case in which all available subcarriers are divided into eight subcarrier groups is exemplified. The tone-based method using two symbols is similar in principle to the above-described tone-based method. Hereinafter, the tone-based scheme using two symbols will be mainly described with respect to differences from the tone-based scheme using one symbol.

As illustrated in FIG. 4 , the group names of each of the eight subcarrier groups are Z, Y, X, W, Z', Y', X', W'. Codewords (Z, Y, X, W, Z', Y', X', W') of length 8 may be generated. The subcarriers represented by Z, Y, X, and W, which are elements of the codeword, correspond to the first time-domain symbol, and the subcarriers represented by Z', Y', X', and W', which are elements of the codeword, correspond to the first time-domain symbol. corresponding to the second time-domain symbol adjacent to . Each subcarrier group includes E subcarriers. That is, each of Z, Y, X, W, Z', Y', X', and W', which are elements of the codeword, has a positive integer value from 0 to E-1.

When the total number of TOIDs is less than the total number of codewords, codewords having at least two Hamming distances between codewords may be mapped to TOIDs. Specifically, one TOID is mapped to one codeword (Z, Y, X, W, Z', Y', X', W'). Here, one codeword (Z, Y, X, W, Z', Y', X', W') is an 8 subcarrier group (four subcarrier groups corresponding to a first time domain symbol, a second time domain 4 subcarrier groups corresponding to the symbol), and each TOID represents a timing offset value.

According to the method using a plurality of symbols, even if some subcarrier groups are lost due to severe deep fading, the receiving terminal can correctly detect the TOID through the remaining element values. In addition, according to the method using a plurality of symbols, a kind of diversity gain may be obtained. In addition, according to the tone-based method using a plurality of symbols, since the transmitting terminal drives signal power to one subcarrier belonging to each subcarrier group, PAPR may be very low.

Meanwhile, although the tone-based method and the sequence-based method for carrying timing offset information have been described so far, this is only an example. The tone-based scheme and the sequence-based scheme according to an embodiment of the present invention may be applied to CWIF or CDF in addition to TOIF. That is, the tone-based method and the sequence-based method according to an embodiment of the present invention can be applied to a case of carrying contention window size information or collision detection information in addition to timing offset information.

On the other hand, as a method of carrying information (eg, timing offset information (TOID), contention window size information (CWID: Contention Window Indication iDentifier), etc.) designed under the time domain structure (SSF1 to SSF4) of the sync slot included in the frame, In addition to the above-described method using orthogonality of signals of the physical layer (a method not using a channel coding method), a method of applying all possible channel coding methods may also be included in the scope of the present invention.

In addition, as a method of carrying information (eg, timing offset information (TOID), contention window size information (CWID), etc.) designed under the time domain structure (SSF1 to SSF4) of the synchronization slot included in the frame, A method of using signal orthogonality and a method of mixing one of all possible channel coding methods may also be included in the scope of the present invention. For example, the transmitting terminal may transmit the timing offset information using the method (eg, tone-based method, sequence-based method) using the orthogonality of the signal of the physical layer described above, and transmit contention window size information using the channel coding method. there is. For another example, the transmitting terminal transmits contention window size information using the method (eg, tone-based method, sequence-based method) using the orthogonality of the signal of the physical layer described above, and transmits the timing offset information using the channel coding method can

5 is a diagram showing the configuration of the terminal 100 according to an embodiment of the present invention.

The terminal 100 includes a processor 110 , a memory 120 , and a radio frequency (RF) converter 130 .

The processor 110 may be configured to implement procedures, functions, and methods related to the terminal described with reference to FIGS. 1 to 4 .

The memory 120 is connected to the processor 110 and stores various information related to the operation of the processor 110 .

The RF converter 130 is connected to the processor 110 and transmits or receives a wireless signal. And the terminal 100 may have a single antenna or multiple antennas.

On the other hand, the embodiment of the present invention may be applied to a transmitter or a receiver other than the terminal 100 .

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improved forms of the present invention are also provided by those skilled in the art using the basic concept of the present invention as defined in the following claims. is within the scope of the right.

Claims (20)

A method for a transmitter to transmit control information, comprising:
determining a first value to be transmitted among the values of the control information;
determining a first codeword corresponding to the first value from among a plurality of codewords;
determining a plurality of first subcarriers corresponding to a plurality of elements belonging to the first codeword; and
allocating a busy tone to the plurality of first subcarriers;
including,
wherein each of the plurality of first subcarriers belongs to each of a plurality of subcarrier groups. In claim 1,
The control information includes at least one of timing offset information and contention window size information, and the timing offset information indicates a time difference between a start point of a frame and a start point of transmission of a preamble. In claim 1,
When the plurality of elements belonging to the first codeword are (z, y, x, w),
a first subcarrier corresponding to the z element among the first subcarriers belongs to a first subcarrier group among the plurality of subcarrier groups;
a first subcarrier corresponding to the y element among the first subcarriers belongs to a second subcarrier group among the plurality of subcarrier groups;
a first subcarrier corresponding to the element x among the first subcarriers belongs to a third subcarrier group among the plurality of subcarrier groups;
and a first subcarrier corresponding to the w element among the first subcarriers belongs to a fourth subcarrier group among the plurality of subcarrier groups. In claim 1,
When the plurality of elements belonging to the first codeword are (z, y),
a first subcarrier corresponding to the z element among the first subcarriers belongs to a first subcarrier group among the plurality of subcarrier groups;
and a first subcarrier corresponding to the y element among the first subcarriers belongs to a second subcarrier group among the plurality of subcarrier groups. In claim 2,
The frame is
a first interval in which the preamble is transmitted, and
and a second interval in which the control information is transmitted and located immediately following the first interval. In claim 1,
Transmitting a preamble for providing synchronization of frames in a network in which no infrastructure exists
Further comprising, wherein the transmitter is an access point (AP) and a different terminal from the base station, the method. In claim 1,
allocating 1/N of a maximum power for one time domain symbol to each of the busy tones allocated to the N first subcarriers when the number of the plurality of first subcarriers is N;
Further comprising, N is a natural number greater than or equal to 2, the method. In claim 1,
and a second codeword of the plurality of codewords has at most two elements of the plurality of elements belonging to the first codeword. In claim 1,
at least one of the plurality of subcarrier groups corresponds to a first time domain symbol and at least another of the plurality of subcarrier groups corresponds to a second time domain symbol. In claim 2,
A sync slot included in the frame,
a first section in which the preamble is transmitted;
A nulling section located immediately before the first section and reducing signal collision;
a second section located immediately after the first section and transmitting the timing offset information; and
A third section located immediately after the second section and transmitting the contention window size information
A method comprising
delete delete delete delete delete delete delete delete delete delete

Images