KR20180031925A - Method for generating and trasmitting downlink preamble in wireless communication system - Google Patents

Method for generating and trasmitting downlink preamble in wireless communication system Download PDF

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KR20180031925A
KR20180031925A KR1020160120410A KR20160120410A KR20180031925A KR 20180031925 A KR20180031925 A KR 20180031925A KR 1020160120410 A KR1020160120410 A KR 1020160120410A KR 20160120410 A KR20160120410 A KR 20160120410A KR 20180031925 A KR20180031925 A KR 20180031925A
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South Korea
Prior art keywords
preamble
generating
tone spacing
user terminal
preambles
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KR1020160120410A
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Korean (ko)
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KR101883064B1 (en
Inventor
홍대식
이학건
김현수
임성묵
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연세대학교 산학협력단
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Priority to PCT/KR2016/013316 priority patent/WO2018056507A1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2666—Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2676—Blind, i.e. without using known symbols
    • H04L27/2678—Blind, i.e. without using known symbols using cyclostationarities, e.g. cyclic prefix or postfix
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2692—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with preamble design, i.e. with negotiation of the synchronisation sequence with transmitter or sequence linked to the algorithm used at the receiver

Abstract

The present invention discloses a method for generating and transmitting a downlink preamble in a wireless communication system supporting a variable tone spacing (VTS) which allows a user terminal assigned with different tone spacing to estimate time synchronization through one preamble structure. The disclosed method for generating a downlink preamble comprises the following steps of: determining a tone spacing interval with respect to first and second user terminals; generating a first preamble of the determined length according to a first tone spacing interval for the first user terminal; generating a second preamble of the determined length according to a second tone spacing interval for the second user terminal; and overlapping the first and second preambles, and generating a third preamble so that a cyclic prefix (CP) of the second preamble is located between preamble sequences.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for generating a downlink preamble in a wireless communication system,

The present invention relates to a method of generating and transmitting a downlink preamble in a wireless communication system, and more particularly, to a method of generating and transmitting a downlink preamble in a wireless communication system supporting variable tone spacing (VTS).

Currently, OFDM technology is being used in wireless communication systems such as mobile communication and wireless LAN. OFDM is a technique for transmitting data using a plurality of subcarriers spaced apart at regular intervals.

On the other hand, in order to obtain a higher data rate in a wireless communication system, a larger frequency band is required, and Carrier Aggregation (CA) is used as a solution. However, since users communicate with each other in different channel environments, inter-symbol interference (ISI) and inter-carrier interference (ICI) are used in a situation where the degree and type of interference vary depending on the channel environment and the interval between sub- There are problems that are all difficult to control.

Recently, research on VTS (Variable Tone Spacing) -OFDM in which data is transmitted by adjusting tone spacing for each user is under way.

In the related art, non-patent literature "S. Lim, G. Noh, J. Heo, H. Kim and D. Hong," OFDMA with variable tone spaces, "IEEE Wireless Communications vol. 19, . 113-120, December 2012. "There is.

1 is a diagram showing subcarriers of a wireless communication system supporting variable tone spacing and symbol lengths in a time domain.

Tone spacing is the spacing of subcarriers (

Figure pat00001
), And tone spacing in a wireless communication system supporting variable tone spacing may be differently assigned for each group of users. In FIG. 1 (a), the tone spacing interval allocated to the second user group is two times the tone spacing interval of the first user group. In general, the tone spacing frequency spacing difference can be set to 2 n (n is a natural number).

When different tone spacings are allocated to different users, a difference occurs in the length of symbols transmitted in the time domain for each user group as shown in FIG. 1 (b) due to the frequency difference. As shown in FIG. 1 (a), when the tone spacing interval is two times different, the symbol length in the time domain also doubles.

Therefore, the length of the preamble transmitted from the base station to the user terminal for time synchronization also varies according to the first and second user groups. Consequently, preambles having different structures for the first and second user groups must be used. This can increase the complexity of the system and reduce the transmission speed. Therefore, it is necessary to study a method of synchronizing time synchronization in both the first and second user groups with a single preamble structure.

The present invention provides a preamble generation and transmission method for allowing a user terminal having different tone spacings to estimate time synchronization through a single preamble structure in a wireless communication system supporting variable tone spacing.

According to an aspect of the present invention, there is provided a method of generating a downlink preamble in a wireless communication system, the method comprising: determining a tone spacing interval for first and second user terminals; Generating a first preamble of a length determined according to a first tone spacing interval for a first user terminal; Generating a second preamble of length determined according to a second tone spacing interval for a second user terminal; And generating a third preamble such that a CP (Cyclic Prefix) of the second preamble is located between preamble sequences by superimposing the first and second preambles.

According to another aspect of the present invention, there is provided a method for generating a downlink preamble in a wireless communication system, the method comprising: generating a first preamble having a length determined according to a first tone spacing interval for a first user terminal; ; Generating a second preamble of length determined according to a second tone spacing interval for a second user terminal; And generating a third preamble by superimposing the first and second preambles in a state in which the ends of the first preamble and the second preamble are synchronized with each other.

According to another aspect of the present invention, there is provided a method for transmitting a downlink preamble in a wireless communication system, the method comprising: receiving a first preamble having a length determined according to a first tone spacing interval for a first user terminal; ; Generating a second preamble of length determined according to a second tone spacing interval for a second user terminal; Generating a third preamble such that a CP (Cyclic Prefix) of the second preamble is located between preamble sequences by superimposing the first and second preambles; And transmitting the third preamble to the first user terminal and the second user terminal.

According to the present invention, in a wireless communication system supporting variable tone spacing, a user terminal can estimate time synchronization of a downlink using one preamble structure.

According to the present invention, a time-synchronization can be estimated by a user assigned different tone spacings using one preamble structure, thereby reducing the complexity of the system and improving the transmission rate.

1 is a diagram showing subcarriers of a wireless communication system supporting variable tone spacing and symbol lengths in a time domain.
2 is a flowchart illustrating a method of generating a downlink preamble in a wireless communication system according to an embodiment of the present invention.
3 is a view for explaining a structure of a downlink preamble according to the present invention.
4 is a flowchart illustrating a method of transmitting a downlink preamble in a wireless communication system according to an embodiment of the present invention.
5 is a diagram illustrating a result of time synchronization estimation in a user terminal using a downlink 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. Like reference numerals are used for like elements in describing each drawing.

In this specification, a base station of a wireless communication system generally refers to a fixed station that communicates with a terminal and may be referred to as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point Can be called.

The user terminal of the wireless communication system may be fixed or mobile and may be a mobile station (MS), a user equipment (UE), a mobile terminal (MT), a subscriber station (SS) A PDA (personal digital assistant), a wireless modem, a handheld device, and the like.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a flowchart illustrating a method of generating a downlink preamble in a wireless communication system according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a structure of a downlink preamble according to the present invention. The method of generating a downlink preamble according to the present invention may be performed in a base station supporting variable tone spacing.

According to the present invention, the base station determines a tone spacing frequency for the first and second user terminals (S210). At this time, the base station can determine the tone spacing according to the channel information transmitted from the first and second user terminals. For example, a user terminal with high mobility may have a high Doppler effect, so that tone spacing can be allocated at a relatively large frequency interval.

The base station generates a first preamble for the first user terminal and a second preamble for the second user terminal in accordance with the determined tone spacing interval. More specifically, a first preamble of a length determined according to a first tone spacing interval for a first user terminal is generated (S220), and a second preamble of a length determined according to a second tone spacing interval for a second user terminal is generated (S230).

Referring to FIG. 3, which shows the structure of the downlink preamble when the tone spacing frequency is two times different, the second tone spacing frequency interval (

Figure pat00002
) Is equal to the first tone spacing frequency interval (
Figure pat00003
, The length of the first preamble 210 is longer than that of the second preamble 220. [

The first and second preambles 210 and 220 include a preamble sequence A for the same time synchronization, and the same preamble sequence is repeatedly allocated. At this time, the number of repetitions of the preamble sequence is determined according to the first and second tone spacing intervals, that is, the symbol length. Since the length of the first preamble 210 is longer than the length of the second preamble 220 according to the first and second tone spacing intervals, the number of repetitions of the preamble sequence for the first preamble 210 is greater than the length of the second preamble 210 220).

The first and second preambles include a CP (Cyclic Prefix) 211 and 221.

2, the base station generates a third preamble 230 such that the CP 221 of the second preamble 220 is located between the preamble sequences by superimposing the first and second preambles 210 and 220 .

3, the BS determines that the termination of the first preamble 210 and the second preamble 220 is synchronized such that the length of the third preamble 230 is the same as the length of the first preamble 210. In this case, The first and second preambles 210 and 220 are overlapped with each other. Accordingly, a third preamble 230 equal to the length of the first preamble 210 can be generated.

A part of the preamble sequence is overlapped by the overlapping of the first and second preambles 210 and 220 so that in the third preamble 230 a preamble sequence of the following stage is generated based on the CP 221 of the second preamble 220 The symbol size (2XA) is an integral multiple, for example, twice the size of the preamble sequence symbols of the first and second preambles 210 and 220.

The base station generates the third preamble 230 by multiplying the CP symbol 211 of the first preamble 210 by an integer so that the first user terminal can easily estimate the time synchronization using the third preamble 230 do.

The user terminal calculates a correlation value for the transmitted preamble and estimates time synchronization through a peak value of a timing metric corresponding to the correlation value. Generally, a peak value is generated in a CP symbol interval. The size of the sequence symbol at the rear end of the third preamble 230 is doubled due to the overlap so that the first user terminal can detect the peak value in the CP symbol 211 of the first preamble 210 The size of the CP symbol 211 of the first preamble 210 is doubled, for example.

In the case of the second user terminal, the size of the preamble sequence at the rear end of the third preamble 230 is doubled compared with the second preamble. However, since the patterns of the symbols are the same, Can be performed.

As a result, according to the present invention, in a wireless communication system supporting variable tone spacing, a user terminal can estimate the time synchronization of the downlink using one preamble structure.

In addition, according to the present invention, a user assigned different tone spacings using one preamble structure can estimate time synchronization, thereby reducing the complexity of the system and improving the transmission rate.

4 is a flowchart illustrating a method of transmitting a downlink preamble in a wireless communication system according to an embodiment of the present invention.

The downlink preamble transmission method according to the present invention transmits a generated preamble to a user terminal to which different tone spacings are allocated as described with reference to FIG. That is, the user terminals assigned different tone spacings all use the same preamble to estimate time synchronization.

More specifically, according to the present invention, a base station generates a first preamble having a length determined according to a first tone spacing interval for a first user terminal (S410), and calculates a length determined according to a second tone spacing interval for a second user terminal (S420). ≪ / RTI > The first and second preambles are superimposed to generate a third preamble such that the CP of the second preamble is located between preamble sequences (S430). Then, the generated third preamble is transmitted to the first and second user terminals (S440).

Since the first and second user terminals are informed of the tone spacing interval allocated thereto by the base station, time synchronization can be estimated from the third preamble, respectively.

For example, since the second user terminal knows the length of a symbol to be transmitted to itself, the second user terminal can estimate the time synchronization by taking a correlation value from the CP symbol of the second preamble included in the third preamble.

5 is a diagram illustrating a result of time synchronization estimation in a user terminal using a downlink preamble according to the present invention.

In FIG. 5, a blue graph is a time synchronization estimation result in the first user terminal in FIG. 1, and a red graph indicates a time synchronization estimation result in the second user terminal in FIG.

As shown in FIG. 5, peak values 510 and 520 of a timing metric indicating time synchronization are detected in both the first and second user terminals, and a peak value detection point is a time synchronization estimation point . In this case, it can be confirmed that the time synchronization estimation point of the second user terminal is further behind the positions of the first and second preambles CP included in the third preamble.

As a result, it can be seen that time synchronization can be estimated in all UEs to which different tone spacings are allocated using the downlink preamble according to the present invention.

The above-described technical features may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (12)

A method for generating a downlink preamble in a wireless communication system,
Determining a tone spacing interval for the first and second user terminals;
Generating a first preamble of a length determined according to a first tone spacing interval for a first user terminal;
Generating a second preamble of length determined according to a second tone spacing interval for a second user terminal; And
Generating a third preamble such that a CP (Cyclic Prefix) of the second preamble is located between preamble sequences by superimposing the first and second preambles
/ RTI >
The method according to claim 1,
The preamble sequences included in the first and second preambles are the same,
Wherein the number of repetitions of the preamble sequence is determined according to the first and second tone spacing intervals
A method for generating a preamble.
3. The method of claim 2,
The step of generating the third preamble
And synchronizing ends of the first preamble and the second preamble to overlap the first and second preambles
A method for generating a preamble.
The method according to claim 1,
The step of generating the third preamble
And multiplying the CP symbol of the first preamble by an integer to generate the third preamble
A method for generating a preamble.
The method according to claim 1,
The length of the third preamble is
Equal to the length of the first preamble
A method for generating a preamble.
The method according to claim 1,
The step of determining tone spacing
Determining tone spacing according to channel information transmitted from the first and second user terminals
A method for generating a preamble.
A method for generating a downlink preamble in a wireless communication system,
Generating a first preamble of a length determined according to a first tone spacing interval for a first user terminal;
Generating a second preamble of length determined according to a second tone spacing interval for a second user terminal; And
Generating a third preamble by superposing the first and second preambles in a state in which the terminal ends of the first preamble and the second preamble are synchronized;
/ RTI >
8. The method of claim 7,
The step of generating the third preamble
And multiplying the CP symbol of the first preamble by an integer to generate the third preamble
A method for generating a preamble.
A method for transmitting a downlink preamble in a wireless communication system,
Generating a first preamble of a length determined according to a first tone spacing interval for a first user terminal;
Generating a second preamble of length determined according to a second tone spacing interval for a second user terminal;
Generating a third preamble such that a CP (Cyclic Prefix) of the second preamble is located between preamble sequences by superimposing the first and second preambles; And
Transmitting the third preamble to the first and second user terminals
/ RTI >
10. The method of claim 9,
The length of the preamble sequence included in the first and second preambles is the same,
Wherein the number of repetitions of the preamble sequence is determined according to the first and second tone spacing frequencies
Preamble transmission method.
10. The method of claim 9,
The step of generating the third preamble
And synchronizing ends of the first preamble and the second preamble to overlap the first and second preambles
A method for generating a preamble.
10. The method of claim 9,
The step of generating the third preamble
And multiplying the CP symbol of the first preamble by an integer to generate the third preamble
A method for generating a preamble.
KR1020160120410A 2016-09-21 2016-09-21 Method for generating and trasmitting downlink preamble in wireless communication system KR101883064B1 (en)

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US20040081131A1 (en) * 2002-10-25 2004-04-29 Walton Jay Rod OFDM communication system with multiple OFDM symbol sizes
US20120027119A1 (en) * 2010-06-15 2012-02-02 Shearer Edwin H S Mixed mode modulation for OFDM
KR102526618B1 (en) * 2013-10-25 2023-04-27 마벨 아시아 피티이 엘티디. Range extension mode for wifi
WO2015161068A1 (en) * 2014-04-16 2015-10-22 Marvell World Trade Ltd. Signal field length indication in a high efficiency wireless local area network (wlan)

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Title
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