KR20200122831A - Method and apparatus for transmitting and receiving synchronization signal in communication system - Google Patents

Abstract

A method for operating a terminal in a mobile communication system comprises the following steps of: receiving a synchronization signal/physical broadcasting channel (SS/PBCH) block from a base station; generating a frequency transition signal by transiting the frequency of a signal based on a difference between a frequency corresponding to a global synchronization channel number (GSCN) of a primary synchronization signal (PSS) included in the SS/PBCH block and a central frequency of a filter included in the terminal; filtering the frequency transition signal to generate a filtered signal; downsampling the filtered signal to generate a downsampled signal; and detecting synchronization information from the downsampled signal by performing a correlation operation. Therefore, the synchronization signal can be efficiently transceived.

Description

Synchronization signal transmission/reception method and device in communication system {METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING SYNCHRONIZATION SIGNAL IN COMMUNICATION SYSTEM}

The present invention relates to a method for transmitting and receiving a synchronization signal in a communication system, and more particularly, to a method and apparatus for detecting synchronization information from a signal received by a terminal that has received a signal by shifting the frequency of the signal.

With the development of information and communication technologies, various wireless communication technologies are being developed. Representative wireless communication technologies include long term evolution (LTE) and new radio (NR) specified in the 3rd generation partnership project (3GPP) standard. LTE may be one of 4G (4th Generation) wireless communication technologies, and NR may be one of 5G (5th Generation) wireless communication technologies.

4G communication system as well as the frequency band of the 4G communication system (for example, a frequency band of 6 GHz or less) for the processing of rapidly increasing wireless data after the commercialization of a 4G communication system (for example, a communication system supporting LTE) A 5G communication system (eg, a communication system supporting NR) using a frequency band higher than the frequency band of (eg, a frequency band of 6 GHz or higher) is being considered. The 5G communication system may support enhanced Mobile BroadBand (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and Massive Machine Type Communication (mMTC).

In order to support various services, a variable system configuration needs to be supported. For example, a 5G communication system must be able to support variable subcarrier spacing in a multi-carrier transmission scheme. In a 5G communication system supporting a variable subcarrier spacing, a synchronization signal must be set in consideration of the variable subcarrier spacing. In a 5G communication system, a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) may be disposed at various locations within a band to which a synchronization signal is allocated. When the PSS and SSS are arranged in various locations, the terminal may include a plurality of band pass filters (BPFs) to detect synchronization signals and synchronization information. However, when the terminal includes a plurality of BPFs, a problem of increasing the implementation complexity of the terminal may occur.

An object of the present invention for solving the above problems is to provide a method of shifting the frequency of a signal and obtaining a synchronization signal located in various frequency bands through one low pass filter (LPF). .

A method of operating a terminal in a mobile communication system for achieving the above object includes: receiving a synchronization signal/physical broadcasting channel (SS/PBCH) block from a base station; Frequency shifting by shifting the frequency of the signal based on the difference between the frequency corresponding to the global synchronization channel number (GSCN) of the primary synchronization signal (PSS) included in the SS/PBCH block and the center frequency of the filter included in the terminal Generating a signal; Filtering the frequency shift signal to generate a filtered signal; Downsampling the filtered signal to generate a downsampled signal; And detecting synchronization information from the downsampled signal by performing a correlation operation.

In the method of transmitting and receiving a synchronization signal according to the present invention, the frequency of the signal is shifted, and synchronization information is detected from the frequency-shifted signal through an auto-correlation or cross-correlation operation. Can send and receive signals.

1 is a conceptual diagram showing a first embodiment of a wireless communication network.
2 is a block diagram showing a first embodiment of a communication node constituting a wireless communication network.
3 is a conceptual diagram showing a first embodiment of a system frame configuration in a wireless communication network.
4 is a conceptual diagram showing a first embodiment of a subframe configuration in a wireless communication network.
5 is a conceptual diagram showing a first embodiment of a slot configuration in a wireless communication network.
6 is a conceptual diagram showing a second embodiment of a slot configuration in a wireless communication network.
7 is a conceptual diagram illustrating a first embodiment of a time-frequency resource in a wireless communication network.
8 is a conceptual diagram showing a first embodiment of a synchronization signal/physical broadcasting channel (SS/PBCH) block in a wireless communication network.
9 is a flow chart illustrating an embodiment of a method for transmitting and receiving a synchronization signal between a base station and a terminal.
10 is a flowchart illustrating an embodiment of a method of determining a correlation calculation method of a terminal during a synchronization detection operation.
11 is a graph showing an embodiment of a cell detection probability according to a correlation calculation method.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

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

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

A wireless communication network to which embodiments according to the present invention are applied will be described. The wireless communication network to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various wireless communication networks. Here, the wireless communication network may have the same meaning as a wireless communication system.

1 is a conceptual diagram showing a first embodiment of a communication system.

Referring to FIG. 1, a communication system 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Here, the communication system may be referred to as a “communication network”. Each of the plurality of communication nodes may support at least one communication protocol. For example, each of the plurality of communication nodes is a communication protocol based on code division multiple access (CDMA), a communication protocol based on wideband CDMA (WCDMA), a communication protocol based on time division multiple access (TDMA), and frequency division multiple access (FDMA). access) based communication protocol, OFDM (orthogonal frequency division multiplexing) based communication protocol, OFDMA (orthogonal frequency division multiple access) based communication protocol, SC (single carrier)-FDMA based communication protocol, NOMA (non-orthogonal multiple) access)-based communication protocol, space division multiple access (SDMA)-based communication protocol, etc. may be supported. Each of the plurality of communication nodes may have the following structure.

2 is a block diagram showing an embodiment of a communication node constituting a communication system.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transmission/reception device 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, and a storage device 260. Each of the components included in the communication node 200 may be connected by a bus 270 to perform communication with each other. However, each of the components included in the communication node 200 may be connected through an individual interface or an individual bus centering on the processor 210 instead of the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transmission/reception device 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface. .

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be configured with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may be formed of at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1, the communication system 100 includes a plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and a plurality of user equipment (UEs). ) (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third UE 130-3 and the fourth UE 130-4 may belong to the coverage of the first base station 110-1. The second UE 130-2, the fourth UE 130-4, and the fifth UE 130-5 may belong to the coverage of the second base station 110-2. The fifth base station 120-2, the fourth UE 130-4, the fifth UE 130-5, and the sixth UE 130-6 may belong within the coverage of the third base station 110-3. . The first UE 130-1 may belong to the coverage of the fourth base station 120-1. The sixth UE 130-6 may belong to the coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, a base transceiver station (BTS), Radio base station, radio transceiver, access point, access node, road side unit (RSU), digital unit (DU), cloud digital unit (CDU) , A radio remote head (RRH), a radio unit (RU), a transmission point (TP), a transmission and reception point (TRP), a relay node, and the like. Each of the plurality of UEs 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a terminal, an access terminal, a mobile terminal, Station (station), subscriber station (subscriber station), mobile station (mobile station), portable subscriber station (portable subscriber station), node (node), may be referred to as a device (device).

A plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Each of them may support cellular communication (eg, long term evolution (LTE), LTE-A (advanced), etc. specified in the 3rd generation partnership project (3GPP) standard). Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in a different frequency band or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul or a non-ideal backhaul, and the ideal backhaul Alternatively, information can be exchanged with each other through non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding UEs 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and a signal received from the corresponding UE (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Can be transferred to.

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can support OFDMA-based downlink transmission, and SC-FDMA-based uplink ) Can support transmission. In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits multiple input multiple output (MIMO) (eg, single user (SU)-MIMO, Multi-user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation transmission, transmission in an unlicensed band, device to device, D2D ) Communication (or ProSe (proximity services), etc.) Here, each of the plurality of UEs 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a base station Operation corresponding to (110-1, 110-2, 110-3, 120-1, 120-2), by base station (110-1, 110-2, 110-3, 120-1, 120-2) You can perform supported operations.

Next, methods of operation of a communication node in a wireless communication network will be described. Even when a method performed in the first communication node (for example, transmission or reception of a signal) among communication nodes is described, the second communication node corresponding thereto is a method corresponding to the method performed in the first communication node (e.g. For example, signal reception or transmission) may be performed. That is, when the operation of the UE is described, the corresponding base station may perform the operation corresponding to the operation of the UE. Conversely, when the operation of the base station is described, the UE corresponding thereto may perform an operation corresponding to the operation of the base station.

3 is a conceptual diagram showing a first embodiment of a system frame configuration in a wireless communication network.

Referring to FIG. 3, in a wireless communication network, time resources may be divided into frames. For example, a system frame having a length of 10 ms (millisecond) on the time axis of the wireless communication network may be continuously set. The system frame number (SFN) may be set to #0 to #1023. In this case, 1024 system frames may be repeated on the time axis of the wireless communication network. For example, the SFN of the system frame after the system frame #1023 may be #0. One system frame may include two half frames, and the length of one half frame may be 5 ms. A half frame located in the start area of the system frame may be referred to as "half frame #0", and a half frame located in the end area of the system frame may be referred to as "half frame #1". The system frame may include 10 subframes, and the length of one subframe may be 1 ms. Ten subframes within one system frame may be referred to as "subframes #0 to 9".

4 is a conceptual diagram showing a first embodiment of a subframe configuration in a wireless communication network.

Referring to FIG. 4, one subframe may include n slots, and n may be an integer of 1 or more. Therefore, one subframe may be composed of one or more slots.

5 is a conceptual diagram showing a first embodiment of a slot configuration in a wireless communication network.

Referring to FIG. 5, one slot may include one or more OFDM symbols. For example, one slot may consist of 14 OFDM symbols. Here, the length of the slot may vary depending on the number of OFDM symbols included in the slot and the length of the OFDM symbol. The OFDM symbol may be set as a downlink symbol, a flexible symbol, or an uplink symbol.

6 is a conceptual diagram showing a second embodiment of a slot configuration in a wireless communication network.

Referring to FIG. 6, one slot may include 7 OFDM symbols. Here, the length of the slot may vary depending on the number of OFDM symbols included in the slot and the length of the OFDM symbol. The OFDM symbol may be set as a downlink symbol, a flexible symbol, or an uplink symbol.

7 is a conceptual diagram illustrating a first embodiment of a time-frequency resource in a wireless communication network.

Referring to FIG. 7, a resource composed of one OFDM symbol in the time axis and one subcarrier in the frequency axis may be defined as “resource element (RE)”. Resources consisting of one OFDM symbol in the time axis and K subcarriers in the frequency axis may be defined as "REG (resource element group)". REG may include K REs. Here, K may be 12. A resource consisting of N OFDM symbols in the time axis and K subcarriers in the frequency axis may be defined as a "resource block (RB)". Here, N may be 6, 7, or 14. RB can be used as a basic unit of data resource allocation.

Next, a method of transmitting and receiving signals between the base station and the UE will be described. Here, the signal may be system information, control information, user data, or the like. The base station may transmit common information about a cell (eg, a cell formed by the base station) to UEs in the cell. The common information may be common system information, common control information, or the like. Common information may be transmitted to UEs in a cell in a broadcast manner, and accordingly, a channel used for transmission and reception of common information may be referred to as a “physical broadcast channel (PBCH)”. Here, the channel may refer to a physical time-frequency resource.

In addition, the base station may transmit a synchronization signal along with the PBCH to UEs in the cell in a broadcast manner. The synchronization signal may be used to detect time synchronization of the cell. The set of synchronization signals and PBCHs may be referred to as “synchronization signal block” or “SS/PBCH block”. The synchronization signal may include a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), and the SS/PBCH block may further include a PBCH demodulation reference signal (DMRS) used for demodulation of the PBCH.

8 is a conceptual diagram illustrating a first embodiment of an SS/PBCH block in a wireless communication network.

Referring to FIG. 8, an SS/PBCH block may be composed of four OFDM symbols on a time axis. Among the four OFDM symbols, the first symbol (ie, symbol #n) may be composed of PSS, and the second symbol (ie, symbol #n+1) among four OFDM symbols may be composed of PBCH, Of the four OFDM symbols, the third symbol (ie, symbol #n+2) may be composed of SSS, and the fourth symbol (ie, symbol #n+3) of four OFDM symbols may be composed of PBCH. have. Each of the PSS and SSS may be a specific sequence, and may be used for detection of synchronization information and cell information in the UE. PBCH can be used to convey cell-related information.

According to another embodiment, the SS/PBCH block may consist of 4 OFDM symbols on the time axis. Among the four OFDM symbols, the first symbol (ie, symbol #n) may be composed of PSS, and the second symbol (ie, symbol #n+1) among four OFDM symbols may be composed of PBCH, Among the four OFDM symbols, the third symbol (i.e., symbol #n+2) can be composed of SSS and PBCH, and the fourth symbol (i.e., symbol #n+3) of four OFDM symbols is composed of PBCH. Can be.

Meanwhile, the center frequency Fs of the frequency band in which the SS/PBCH block is transmitted may be predefined. In this case, the base station may transmit an SS/PBCH block based on a predefined center frequency (Fs). In addition, the subcarrier interval used for transmission of the SS/PBCH block may be predefined. Alternatively, the center frequency (Fs) of the frequency band in which the SS/PBCH block is transmitted may be predefined, and the base station may variably set the subcarrier interval in the corresponding frequency band, and the SS/PBCH based on the set subcarrier interval Block can be transmitted.

The base station may transmit a plurality of SS/PBCH blocks in one bandwidth portion, and a plurality of SS/PBCH blocks may be transmitted by being multiplexed on a frequency axis of one bandwidth portion. Here, a plurality of SS/PBCH blocks may be transmitted using the same time resource or different time resources. SS/PBCH blocks transmitted according to different center frequencies may be generated based on the same cell ID. Signals (eg, PSS, SSS, PBCH) included in the SS/PBCH block may be generated based on the same SS/PBCH block index. SS/PBCH blocks transmitted through different frequencies in one bandwidth part may be classified into a cell definition SS/PBCH block and a measurement SS/PBCH block. The cell definition SS/PBCH block may be used for synchronization/channel estimation, transmission of common cell information, and the like in a bandwidth portion in which the cell definition SS/PBCH block is transmitted. The measurement SS/PBCH block may be used for measuring channel quality in a frequency band in which the measurement SS/PBCH block is transmitted. The base station may inform the UE of information indicating the type of the SS/PBCH block (eg, a cell definition SS/PBCH block or a measurement SS/PBCH block).

9 is a flow chart illustrating an embodiment of a method for transmitting and receiving a synchronization signal between a base station and a terminal.

9, the base station 910 may generate an SS/PBCH block (S910). The SS/PBCH block may include PSS, SSS and PBCH. PSS may be defined in the form of an m-sequence of 127 samples. The m-sequence of PSS may be defined based on Equation 1.

은 PSS의 m-시퀀스(

)를 정의하기 위해 사용되는 서브 시퀀스(sub sequence)일 수 있다. m-시퀀스(

) 및 서브 시퀀스(

)는 0 또는 1로 구성되는 바이너리(binary) 시퀀스일 수 있다. 서브 시퀀스(

)는 수학식 2에 기초하여 정의될 수 있다.In Equation 1, u may indicate a cell ID and may be one of {0,1,2}.

Is the m-sequence of PSS (

) May be a subsequence used to define. m-sequence (

) And subsequences (

) May be a binary sequence consisting of 0 or 1. Subsequence(

) May be defined based on Equation 2.

인 경우,

크기의 초기 시퀀스가 정의될 수 있다. 일 실시예에 따르면 정의된 서브 시퀀스의 초기 시퀀스는 {0,1,1,0,1,1,1}일 수 있다. 수학식 2에서

인 경우, 서브 시퀀스는 수학식 2에 기초하여 계산될 수 있다. S₁은 0부터

사이의 정수로 구성되는 임의의 집합으로 정의될 수 있다. S₁은 0을 반드시 포함할 수 있다.

는 S₁에 속하는 k를 의미할 수 있다. 예를 들어, M₁=7 이고, S₁ = 0, 4 인 경우, 서브 시퀀스

는 수학식 3에 기초하여 정의될 수 있다.M ₁ may indicate the length of the initial sequence of the subsequence. In Equation 2

If is,

An initial sequence of sizes can be defined. According to an embodiment, the initial sequence of the defined subsequence may be {0,1,1,0,1,1,1}. In Equation 2

In the case of, the subsequence may be calculated based on Equation 2. S ₁ from 0

It can be defined as an arbitrary set consisting of integers between. S ₁ may necessarily contain 0.

May mean k belonging to S ₁ . For example, if M ₁ =7 and S ₁ = 0, 4 then subsequence

May be defined based on Equation 3.

The base station 910 may generate an m-sequence of PSS based on Equations 1 to 3. The base station 910 may allocate the m-sequence of the generated PSS to a plurality of subcarriers included in the SS/PBCH block. The base station 910 may allocate the PSS sequence to 240 subcarriers, and may allocate the PSS sequence to the subcarrier as shown in Equation 4 below.

일 수 있으며, GSCN(global synchronization channel number)에 상응하는 주파수(

)에 위치할 수 있다. 기지국(910)은 수학식 4에 의해 PSS를 포함하는 SS/PBCH 블록을 생성할 수 있다. 기지국(910)은 적어도 하나 이상의 SS/PBCH 블록을 포함하는 신호를 생성할 수 있으며(S910), 기지국(910)은 단말(920)로 하나 이상의 SS/PBCH 블록을 전송할 수 있다(S920). The base station 910 may allocate a PSS sequence to 127 subcarriers (56th subcarrier to 182th subcarrier) located in the middle of 240 subcarriers. The center of the PSS sequence is

It may be, and a frequency corresponding to the global synchronization channel number (GSCN) (

) Can be located. The base station 910 may generate an SS/PBCH block including the PSS according to Equation 4. The base station 910 may generate a signal including at least one SS/PBCH block (S910), and the base station 910 may transmit one or more SS/PBCH blocks to the terminal 920 (S920).

) 부근의 신호를 추출하기 위해 신호의 주파수를 천이할 수 있다(S930). 주파수 천이된 신호는 수학식 5와 같이 표현될 수 있다. The terminal 920 may receive one or more SS/PBCH blocks from the base station 910 (S920), and the terminal 920 may extract at least one PSS from the SS/PBCH block. The terminal 920 is the GSCN frequency of at least one PSS among signals received from the base station 910 in S920 (

) The frequency of the signal may be shifted in order to extract a signal in the vicinity (S930). The frequency-shifted signal can be expressed as in Equation 5.

는 샘플링 주파수를 지시할 수 있고,

는 i번째 PSS의 GSCN 주파수(

)와 단말(920)에 포함된 필터의 중심 주파수 간의 차이를 지시할 수 있다. 주파수 천이된 신호의 중심 주파수에는 PSS 시퀀스의

가 배치될 수 있다. In Equation 5,

Can indicate the sampling frequency,

Is the GSCN frequency of the i-th PSS (

) And the center frequency of the filter included in the terminal 920 may be indicated. The center frequency of the frequency-shifted signal is the PSS sequence.

Can be placed.

The terminal 920 may include a filter, and the filter included in the terminal 920 may be one low pass filter (LPF). The terminal 920 may filter the frequency-shifted signal (S940). The terminal 920 may generate a filtered signal by filtering a signal near the center frequency of the frequency-shifted signal through the LPF (S940). The signal filtered by the LPF of the terminal 920 may be expressed as in Equation 6.

The terminal 920 may acquire the filtered signal near the center frequency, and downsamp the filtered signal to reduce the complexity of the synchronization information detection process (S950). The terminal 920 may generate a downsampled signal from the filtered signal based on a preset downsample rate M (S950). The downsampled signal generated by the terminal 920 can be expressed as in Equation 7.

The terminal 920 may perform a correlation operation to detect synchronization information from the downsampled signal (S960). Specifically, the terminal 920 may perform a cross correlation operation or an auto correlation operation to detect synchronization information from the downsampled signal (S960).

10 is a flowchart illustrating an embodiment of a method of determining a correlation calculation method of a terminal during a synchronization detection operation.

Referring to FIG. 10, the terminal 920 may determine a correlation calculation method based on signal to noise ratio (SNR) information of a signal (eg, an SS/PBCH block) (S961-1). For example, when the SNR value of the received signal is lower than a preset threshold value, the terminal 920 may perform a cross-correlation operation to detect synchronization information from the downsampled signal (S962-1). In addition, when the SNR value of the received signal is higher than the preset threshold value, the terminal 920 may detect synchronization information from the downsampled signal by performing an autocorrelation operation (S962-2).

In addition, referring to FIG. 10, the terminal 920 may determine a correlation calculation method based on carrier frequency offset (CFO) information of a signal (eg, an SS/PBCH block) (S961-2). For example, when the CFO of the received signal is lower than a preset threshold value, the terminal 920 may perform a cross-correlation operation to detect synchronization information from the downsampled signal (S962-1). In addition, when the CFO of the received signal is higher than a preset threshold value, the terminal 920 may detect synchronization information from the downsampled signal by performing an auto-correlation operation (S962-2).

The terminal 920 may calculate a correlation value for each section from the downsampled signal by performing a cross-correlation operation. In addition, the terminal 920 may detect synchronization information based on a correlation value for each section (S962-1). The terminal 920 may detect the starter, frequency synchronization, and cell ID by performing the operation of Equation (8).

는

를 IDFT(inverse discrete Fourier transform)한 시간 영역 신호를 의미할 수 있다. 단말(920)은 IDFT된 PSS 시퀀스와 다운샘플된 수신 신호간에 상호 상관 연산을 수행할 수 있으며, 상호 상관 연산의 결과 값에 기초하여 동기 정보를 검출할 수 있다(S962-1). In Equation 8

Is

May mean a time domain signal obtained by inverse discrete Fourier transform (IDFT). The terminal 920 may perform a cross-correlation operation between the IDFTed PSS sequence and the downsampled received signal, and may detect synchronization information based on the result of the cross-correlation operation (S962-1).

The terminal 920 may generate a correlation value between the IDFTed PSS sequence and the downsampled received signal by performing a correlation operation for each time period. The terminal 920 may compare a correlation value between the IDFTed PSS sequence for each time period and the downsampled received signal, and determine a time index at the time of having the largest correlation value as a starter.

The terminal 920 may generate a correlation value between the IDFTed PSS sequence and the downsampled received signal by performing a correlation operation for each frequency section. The terminal 920 may compare the correlation values for each frequency section and determine a frequency when having the largest correlation value as frequency synchronization.

In addition, the terminal 920 may perform a correlation operation for each cell ID to generate a correlation value between the IDFTed PSS sequence and the downsampled received signal. The terminal 920 may compare the correlation values for each cell ID, and determine the cell ID when the cell ID has the largest correlation value as the cell ID of the synchronization signal.

Alternatively, the terminal 920 may calculate a correlation value for each section from the downsampled signal by performing an autocorrelation operation. In addition, the terminal 920 may detect synchronization information based on a correlation value for each section. The terminal 920 may detect starter and frequency synchronization information by performing the operation of Equation 9 (S962-2).

In Equation 9, L may denote a period of PSS, and N may denote a correlation window. The terminal 920 may generate an autocorrelation value of the downsampled received signal by performing a correlation operation for each frequency section. The terminal 920 may compare the autocorrelation values for each frequency section and determine a frequency when having the largest correlation value as frequency synchronization.

In addition, the terminal 920 may generate an autocorrelation value of the downsampled received signal by performing a correlation operation for each time period. The terminal 920 may compare the correlation values for each time section and determine a time index when having the largest correlation value as the starter (S962-2). The terminal 920 that detects the starter and frequency synchronization information from the downsampled signal may detect the cell ID by performing the operation of Equation 10.

는 주파수 신호일 수 있으며, 수학식 11과 같이 정의될 수 있다. In Equation 10

May be a frequency signal, and may be defined as in Equation 11.

The terminal 920 may calculate a correlation value between the sequence of PSS and the sequence of Equation 11 by performing a correlation operation for each cell ID. In addition, the terminal 920 may compare the correlation values for each cell ID and determine the cell ID information when the cell ID has the largest correlation value as the cell ID of the synchronization signal.

은 서로 인접하게 배치될 수 있다. 예를 들어, 3GHz 이하의 주파수 대역의 신호에 포함된 3개의

(예를 들어,

)은 100kHz 단위로 배치될 수 있다. 상호 상관 연산을 수행하여 동기 정보를 검출하는 경우(S962-1), 단말(920)은 3개의

각각에 대해 독립적으로 주파수 천이를 수행하여 주파수 천이된 신호를 생성할 수 있다. 단말(920)은 필터링을 수행하여 각각의 주파수 천이된 신호로부터 필터링된 신호를 생성할 수 있다. 단말(920)은 각각의 필터링된 신호와 IDFT된 PSS 시퀀스 간에 상호 상관 연산을 수행하여 주파수 동기, 시동기 및 셀 ID를 탐지할 수 있다. A plurality of signals included in a signal of a frequency band below a certain range

May be placed adjacent to each other. For example, in a signal in a frequency band below 3 GHz,

(For example,

) Can be placed in units of 100 kHz. When detecting synchronization information by performing a cross-correlation operation (S962-1), the terminal 920

A frequency shifted signal may be generated by performing frequency shifting independently for each. The terminal 920 may perform filtering to generate a filtered signal from each frequency-shifted signal. The terminal 920 may detect frequency synchronization, starter, and cell ID by performing a cross-correlation operation between each filtered signal and the IDFTed PSS sequence.

의 주파수 중 중간 값인

를 기준으로 주파수 천이를 수행하여 주파수 천이된 신호를 생성할 수 있다. 단말(920)은 필터링을 수행하여 주파수 천이된 신호로부터 필터링된 신호를 획득할 수 있다. 단말(920)은 필터링된 신호를 자기 상관 연산을 수행하여 주파수 동기 및 시동기 정보를 검출할 수 있다. When detecting synchronization information by performing an autocorrelation operation (S962-2), the terminal 920

Is the middle value of

A frequency shifted signal may be generated by performing a frequency shift based on. The terminal 920 may perform filtering to obtain a filtered signal from the frequency-shifted signal. The terminal 920 may detect frequency synchronization and starter information by performing an auto-correlation operation on the filtered signal.

The terminal 920 having detected the frequency synchronization and starter information may detect the cell ID by performing the correlation operation of Equation 12.

인자는 미리 설정된 시퀀스 중 하나의 숫자일 수 있으며, {-7, 0, 7} 중 하나의 숫자일 수 있다. 단말(920)은 셀 ID 별로 상관 연산을 수행하여 PSS의 시퀀스와 수학식 11의 시퀀스 간의 상관 값을 산출할 수 있다. 그리고 단말(920)은 셀 ID 별 상관 값을 비교하여 가장 큰 상관 값을 가질 때의 셀 ID 정보를 동기 신호의 셀 ID로 결정할 수 있다. 그리고 단말은

인자 별로 상관 연산을 수행하여 PSS의 시퀀스와 수학식 11의 시퀀스 간의 상관 값을 산출할 수 있다. 그리고 단말(920)은

인자 별 상관 값을 비교하여 가장 큰 상관 값을 가질 때의

인자를 반영하여 동기 신호의 셀 ID 및 중심 주파수

를 검출할 수 있다. GSCN은

로 설정될 수 있다. In Equation 12

The factor may be one number from a preset sequence, and may be one number from {-7, 0, 7}. The terminal 920 may calculate a correlation value between the sequence of PSS and the sequence of Equation 11 by performing a correlation operation for each cell ID. In addition, the terminal 920 may compare the correlation values for each cell ID and determine the cell ID information when the cell ID has the largest correlation value as the cell ID of the synchronization signal. And the terminal

By performing a correlation operation for each factor, a correlation value between the sequence of PSS and the sequence of Equation 11 may be calculated. And the terminal 920

When the correlation value for each factor is compared and has the largest correlation value

Cell ID and center frequency of synchronization signal by reflecting factor

Can be detected. GSCN is

Can be set to

11 is a graph showing an embodiment of a cell detection probability according to a correlation calculation method.

Referring to FIG. 11, when noise of a signal (eg, an SS/PBCH block) is high, a cell search rate of a signal detection method by a cross-correlation operation may be higher than a signal detection method by an auto-correlation operation. In addition, when the CFO of the signal (eg, SS/PBCH block) is high, the cell search rate of the signal detection method by the auto-correlation operation may be higher than that of the signal detection method by the cross-correlation operation.

The methods according to the present invention 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 computer-readable medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software.

Examples of computer-readable media include hardware devices specially configured to store and execute program instructions, such as rom, ram, flash memory, and the like. Examples of program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The above-described hardware device may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (1)

As a method of operating a terminal in a mobile communication system,
Receiving a synchronization signal/physical broadcasting channel (SS/PBCH) block from a base station;
Frequency shifting by shifting the frequency of the signal based on the difference between the frequency corresponding to the global synchronization channel number (GSCN) of the primary synchronization signal (PSS) included in the SS/PBCH block and the center frequency of the filter included in the terminal Generating a signal;
Filtering the frequency shift signal to generate a filtered signal;
Downsampling the filtered signal to generate a downsampled signal; And
And detecting synchronization information from the downsampled signal by performing a correlation operation.

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