KR20150072359A - Method and Apparatus for transmitting/receiving a Synchronization signal in Wireless Communication System - Google Patents

Abstract

The present invention relates to a wireless communication system such as a base station of a wireless communication system, a terminal, a next generation mobile communication system, and a next generation wireless LAN system. More specifically, The present invention relates to a method and an apparatus for transmitting and receiving synchronization signals whereby the base station constructs the synchronization signals to vary depending on a frequency band. Particularly, according to the present invention, a method of the terminal for receiving the synchronization signals includes the steps of: receiving a synchronization signal from either a first cell using a first frequency band or a second cell using a second frequency band; and determining whether the synchronization signal is received through the first frequency band or the second frequency band based on a reception pattern of the synchronization pattern.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous signal transmitting / receiving method and apparatus for a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system such as a base station (wireless router) and a terminal of a wireless communication system, a next generation mobile communication system, and a next generation wireless LAN system. And more particularly, to a method and apparatus for transmitting / receiving a synchronous signal differently according to a frequency band.

A synchronous signal is a signal for synchronizing a base station with a terminal or a wireless local area network (WLAN) AP (access point) in a wireless communication system. The base station or the wireless LAN AP synchronizes time with the terminal using the synchronization signal, and the terminal can adjust the time synchronization of the base station or the wireless LAN AP. Also, the terminal may acquire information on a cell for communication using a synchronization signal.

The synchronization signal is transmitted by the AP of the base station or the wireless LAN, and the terminal receives the synchronization signal.

There is a problem that a frequency resource for wireless communication becomes insufficient due to a surge of terminals using wireless communication and a surge in the amount of communication data.

For this purpose, a method of using a frequency of a license-exempt band that is set for communication using a wireless LAN as a frequency for wireless communication has been discussed. That is, research is underway to carry out communication using the frequency of the license-exempt band for the wireless LAN in the LTE communication system. However, communication using a wireless LAN and communication using wireless communication have different protocols, and there is also a difference in the configuration of a synchronous signal.

In addition, when the existing wireless communication system performs communication using the license-exempt band, signal interference with the wireless LAN AP may increase.

On the other hand, when the terminal performs communication with a wireless communication base station in order to minimize the above-described signal interference, it is necessary to recognize whether the corresponding frequency band is a license band for wireless communication or a license-exempt band for wireless LAN communication.

In the background described above, in order to reduce problems such as signal interference, the terminal needs to distinguish whether the cell that performs communication uses the frequency of the license band or the cell that uses the frequency of the license-exempt band.

Also, the UE needs to quickly determine the characteristics of the frequency band of the cell using only the synchronization signal before confirming the system information of the cell.

According to an aspect of the present invention, there is provided a method of receiving a synchronization signal from a terminal, the method comprising: receiving a synchronization signal from a first cell using a first frequency band and a second cell using a second frequency band; Receiving a synchronization signal and determining which of the first and second frequency bands the synchronization signal has been received based on the reception pattern of the synchronization signal.

According to another aspect of the present invention, there is provided a method of transmitting a synchronization signal, the method comprising: setting a transmission pattern of a synchronization signal according to which frequency band of the first frequency band or the second frequency band is transmitted; And transmitting a synchronization signal using a transmission pattern of a synchronization signal through one of a first cell using a frequency band and a second cell using a second frequency band.

According to another aspect of the present invention, there is provided a terminal for receiving a synchronization signal, comprising: a receiver for receiving a synchronization signal from any one of a first cell using a first frequency band and a second cell using a second frequency band; And a control unit for determining which frequency band of the first frequency band and the second frequency band the synchronization signal is received based on the reception pattern of the received signal.

According to another aspect of the present invention, there is provided a base station for transmitting a synchronization signal, the base station including a control unit for setting a transmission pattern of a synchronization signal according to which frequency band of the first frequency band or the second frequency band is transmitted, And a transmitter for transmitting the synchronization signal using the transmission pattern of the synchronization signal through any one of the first cell using the first frequency band and the second cell using the second frequency band.

In order to reduce the problem of signal interference, the terminal of the present invention can discriminate whether the cell that performs communication uses the frequency of the license band or the cell that uses the frequency of the license-exempt band.

In addition, the terminal of the present invention can quickly determine the characteristics of the frequency band of the corresponding cell using only the synchronization signal before checking the system information of the cell.

1 is a diagram showing a frame structure of an LTE (Long Term Evolution) system.
2 is a diagram showing a PSS and an SSS frame structure in the FDD mode.
3 is a signal diagram illustrating an exemplary operation of a terminal and a base station according to the present invention.
4 is a diagram for explaining a terminal operation according to an embodiment of the present invention.
5 is a diagram illustrating a case where the transmission period of the synchronization signal according to another embodiment of the present invention is set differently.
6 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.
7 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.
8 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.
9 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.
10 is a view for explaining an operation of a base station according to another embodiment of the present invention.
11 is a diagram illustrating a configuration of a terminal according to another embodiment of the present invention.
12 is a diagram illustrating an exemplary terminal configuration operation according to another embodiment of the present invention.
13 is a view showing another example of terminal configuration operation according to another embodiment of the present invention.
14 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) a device itself providing a megacell, a macrocell, a microcell, a picocell, a femtocell, or a small cell in relation to a wireless region, or ii) the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a megacell, a macrocell, a microcell, a picocell, a femtocell, a small cell, an RRH, an antenna, an RU, a low power node (LPN), a point, an eNB, Quot;

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-Advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In systems such as LTE and LTE-Advanced, the uplink and downlink are configured on the basis of one carrier or carrier pair to form a standard. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmission / reception points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multiplex transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiplex transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

First, a frame structure of a wireless communication system will be described with reference to FIG. 1 is a diagram showing a frame structure of an LTE (Long Term Evolution) system.

As shown in FIG. 1, one frame includes ten subframes, and one subframe includes two slots. The time taken to transmit one subframe is called a transmission time interval (TTI). For example, one subframe may be 1 ms and one slot may be 0.5 ms.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols. An OFDM symbol may be referred to as a SCFDMA symbol or a symbol period.

One slot includes seven or six OFDM symbols according to the length of a cyclic prefix (hereinafter referred to as "CP"). The LTE system has a normal CP (normal CP) and an extended CP (extened CP). In the case of using a normal CP, one slot includes seven OFDM symbols, and when an extended CP is used, one slot includes six OFDM symbols. The extended CP is used when the delay spread is large.

A method and apparatus for transmitting and receiving a synchronization signal between a base station and a terminal will be described.

Hereinafter, PSS and SSS will be mainly described as an example of the synchronization signal. However, the PSS and the SSS are only limited to illustrate one example of the synchronization signal. For example, the synchronization signal includes all signals used by the terminal to synchronize with the base station, and the PSS and the SSS .

In order for a terminal to access a cell, a cell search process must be performed. The cell search process consists of a series of synchronization processes by which the UE can determine the time and frequency parameters. Through the synchronization process, the UE can demodulate the downlink signal and transmit the uplink signal at an appropriate time.

There are two types of cell search process: Initial Synchronization and New Cell Identification.

Initial synchronization is performed when the UE first finds a cell and decodes all information to register it in the cell, and is executed when the UE is powered on or disconnected from the serving cell.

The new cell check is performed in the process of detecting a new neighbor cell while the UE is connected to the cell, and the UE reports the measurement value related to the new cell to the serving cell for handover.

In all cells, the base station transmits a synchronization signal, i.e., a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS). The terminal detects the PSS and the SSS before the cell search process (initial synchronization, .

When the UE detects the PSS and SSS signals, not only time and frequency synchronization can be performed, but also the UE can check the physical layer ID and the CP length of the cell, and determine whether the cell uses the FDD or TDD I get the information.

In the case of the initial synchronization, after detecting the synchronization signal, the terminal decodes the PBCH (Physical Broadcast CHannel) and obtains system information (downlink system bandwidth, etc.) from the result.

In the case of new cell identification, the terminal does not need to decode the PBCH and measures the signal quality of the newly detected cell based on the reference signal (RS) and reports it to the serving cell. (LTE is designed to receive RSRP without decoding the PBCH.)

2 is a diagram showing a PSS and an SSS frame structure in the FDD mode.

Referring to FIG. 2, the synchronization signal is transmitted twice every 10ms of radio frames. The PSS and the SSS have different structures depending on whether the terminal is connected to the FDD cell or the TDD cell. Hereinafter, the synchronization signal in the FDD cell will be mainly described for the convenience of understanding, but the same can be applied to the TDD cell.

In the FDD cell, the PSS is located in the first OFDM symbol of the first slot and the 11th slot of the 10-ms radio frame. The slot has six or seven OFDM symbols according to the CP length. Since the PSS is located in the last symbol of the slot, the UE can acquire the slot boundary timing regardless of the CP length. The SSS is located in the previous symbol of the PSS and it is possible to coherently detect the SSS on the basis of the PSS on the assumption that the radio channel characteristic is constant for a time longer than the OFDM symbol length.

The exact position of the SSS is changed according to the length of the CP selected in the cell. Since the UE does not know the length of the CP in advance in the cell detection step, the UE detects and detects two possible SSS positions for the normal CP and the extended CP. If the UE performs a search for both the FDD and the TDD cell, a total of four possible SSS positions should be checked.

In a particular cell, the PSS is the same in all frames transmitted by the cell, whereas in each radio frame, the two SSSs are different in sequence. Therefore, the UE can recognize the boundary of the 10-ms radio frame using the SSS information.

In the frequency domain, the PSS and SSS are mapped to subcarriers in the middle six RBs (resource blocks). Since the number of RBs is in the range of 6 to 110 according to the system bandwidth, the PSS and the SSS are mapped to the six intermediate RBs. Therefore, regardless of the bandwidth of the signal transmitted by the base station, Can be detected. Since PSS and SSS are sequences of 62 symbols each, they are mapped to 62 intermediate subcarriers around the DC subcarriers, and no DC subcarriers are used. Therefore, all of the REs in the middle four RBs of the six RBs are used, but two RBs at both ends of the six RBs use only seven REs, and five REs are not used. The UE will use an FFT of size 64 to detect the PSS, SSS, and the sampling rate will be lower than when using 72 subcarriers.

The UE can acquire the physical layer cell ID by a specific sequence of the PSS and the SSS. LTE has a total of 504 unique physical layer cell IDs, divided into 168 groups, each group consisting of three cell IDs, which are assigned to cells controlled by the same eNodeB. Each group is distinguished by the SSS sequence, and a total of 168 SSS sequences are required to distinguish each group.

On the other hand, PSS uses the Zadoff-Chu (ZC) sequence. ZC sequences are used for random access preamble and uplink reference signals in addition to PSS.

In LTE, three ZC PSSs corresponding to three physical layer IDs are used in each cell group.

The SSS is based on M-se-quence, in which a sequence of length (2 ⁿ -1) is generated by n shift registers. Each SSS sequence is made up of two BPSK modulated sync codes, SSC1 and SSC2, with a length of 31 in the frequency domain, and then the two sequences are alternately inserted into one sequence by interleaving. The two codes for creating SSC1 and SSC2 are generated by cyclically shifting M-sequences of one length 31 differently. At this time, the cyclic shift index is determined by the function of the physical layer cell ID group. SSC2 is scrambled by the sequence determined by the function of the index of SSC1 and further scrambled by the code determined by the function of PSS.

In this way, the synchronization signal in the wireless communication system is very important in the procedure for communication between the terminal and the base station.

In the present specification, the license-exempt band refers to a frequency band used for wireless LAN communication, and the license band refers to a frequency band used for wireless communication such as conventional LTE. Accordingly, the license-exempt band in the present specification is not limited to a specific frequency band but refers to a frequency band used together by the wireless LAN and the base station. That is, in this specification, the license-exempted band means a high frequency band in which there is a high possibility that the wireless LAN and the wireless communication signal will cause mutual interference.

The present invention proposes a method of using a structure of a physical layer used in a mobile communication system such as Long Term Evolution (LTE), for a communication system of another use such as a wireless LAN, with or without a slight modification. The conventional mobile communication system and the wireless LAN differ in the structure of the physical layer because the standards have been standardized in different standardization bodies. In many cases, many terminals include both mobile communication and a receiver for a wireless LAN, but the complexity of the terminal implementation is high because there are many differences between the physical layers of the two systems.

In order to solve such a problem, a method of using a mobile communication standard in a wireless LAN through a slight modification will be described. In the case of wireless LAN, since it is used in the license-exempt band, communication system of other standard can be used without any problem if satisfying a few requirements such as transmission power.

One possible method is to use the physical layer specification in a mobile communication system for a license-exempt band such as a wireless LAN. This has the advantage of reducing the complexity of the terminal. However, in order to find out whether the system captured in the initial acquisition of the terminal is used in the license band like mobile communication or not, it is necessary to perform not only initial acquisition but also demodulation of BCH (Broadcast Channel) Which can lead to a lot of time and power consumption in the acquisition.

Meanwhile, in a mobile communication system, a synchronization channel is often transmitted for the performance of a communication link. In case of 3GPP LTE, the synchronization channel is transmitted twice every 10ms. On the other hand, in the case of a wireless LAN operating in a license-exempt band, a synchronization channel is transmitted at a frequency of about once every 100 ms. This is because, in the case of a wireless LAN, power consumption may increase frequently when a synchronous channel is transmitted, and unnecessary excessive interference may occur to neighboring nodes. Further, since the synchronization channel is continuously transmitted, excessive power consumption can be caused.

Also, in the case of terminal-to-terminal (D2D) communication, which has been actively researched nowadays, power consumption may be excessive if one terminal continuously transmits a synchronization signal. Therefore, there is a need to reduce power consumption by transmitting a synchronization signal only during a predetermined time period.

In order to solve such a problem and allow the terminal to quickly distinguish the license band and the license-exempt band, the present invention proposes a method of transmitting and receiving a synchronous signal.

3 is a signal diagram illustrating an exemplary operation of a terminal and a base station according to the present invention.

Referring to FIG. 3, the base station 300 sets a synchronization signal for transmitting a synchronization signal (S310). That is, the base station 300 determines various settings related to a synchronization signal, such as a resource block to which the synchronization signal is to be transmitted, a synchronization signal transmission period, and a transmission pattern, in order to transmit the synchronization signal. In the present invention, it is assumed that a base station provides two or more cells. That is, the base station may configure two or more cells, and the frequencies used may be different or the same. In addition, although the present invention describes a case where one base station constitutes a cell using two or more different frequency bands, even when different base stations provide cells with different frequency bands, have. However, for convenience of explanation and explanation, a case where one base station provides two or more cells, and each cell is configured to use a different frequency band will be described.

Meanwhile, the base station 300 transmits a synchronization signal to the terminal 310 in accordance with the synchronization signal setting. The synchronization signal may be transmitted for initial connection as described above, or may be transmitted for cell search or the like.

The terminal 310 receives the synchronization signal, analyzes the synchronization signal, and can quickly determine information on the frequency band of the cell in which the synchronization signal is received (S330). That is, it is possible to quickly determine whether the synchronization signal is a frequency band using the license band or a frequency band using the license-exempt band.

Hereinafter, a synchronization signal transmission pattern set differently according to the operation and frequency band of the terminal according to the present invention will be described in detail with reference to the drawings.

4 is a diagram for explaining a terminal operation according to an embodiment of the present invention.

A method of receiving a synchronization signal according to an embodiment of the present invention includes receiving a synchronization signal from one of a first cell using a first frequency band and a second cell using a second frequency band And determining which of the first frequency band and the second frequency band the synchronization signal is received based on the reception pattern of the synchronization signal.

Referring to FIG. 4, the UE includes a step of receiving a synchronization signal from any one of a first cell using a first frequency band and a second cell using a second frequency band (S410). The first frequency band and the second frequency band may be classified according to a use of a preset frequency band. In addition, any one of the first frequency band and the second frequency band may be preliminarily set for use for inter-terminal communication or wireless LAN communication. That is, the above-described license-exempt band may be set to the first frequency band, and the license band may be set to the second frequency band. Or a frequency band for terminal-to-terminal communication may be set to the first frequency band. Accordingly, the first frequency band and the second frequency band may have different frequency bands, and the frequency bandwidth may be the same or different.

Meanwhile, the synchronization signal may include, for example, a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS).

Thereafter, the terminal may include determining which of the first frequency band and the second frequency band the synchronization signal is received based on the reception pattern of the synchronization signal (S420). For example, the UE may check the reception pattern of the synchronization signal transmitted by the base station and determine whether the received synchronization signal is received through the first frequency band or the second frequency band. Conventionally, in order to check the information on the transmission cell or the transmission frequency band of the synchronization signal, it is necessary to use the system information of the PBCH. This increases the power consumption and the verification time of the terminal. Accordingly, the terminal of the present invention can reduce the power consumption of the terminal and can confirm whether the cell transmitting the synchronous signal in a short time uses the first frequency band or the second frequency band. That is, the terminal can quickly confirm whether the frequency band of the license-exempt band is used, thereby performing the terminal operation corresponding to the frequency band of the license-exemption band.

More specifically, the synchronization signal transmitted in the first cell using the first frequency band and the synchronization signal transmitted in the second cell using the second frequency band may be different from one another in that at least one of the transmission period, And can be transmitted. This may mean the above-described reception pattern, whereby the terminal can confirm information on the reception frequency band of the synchronization signal based on only the reception pattern of the synchronization signal. Hereinafter, it will be assumed that the first frequency band is the frequency band of the license-exempt band shared by the wireless LAN, and the second frequency band is assumed to be the license band frequency band for mobile communication. However, this is for the sake of convenience of description, and may be set to the contrary.

Hereinafter, embodiments of a method of setting a synchronization signal according to the frequency band of the present invention will be described in detail with reference to the drawings.

Embodiments of the present invention are described on the assumption that a single standard is created and used for a transmission signal of a mobile communication base station as well as for other purposes. There may be other possible uses for the license-exempt band here. Another application is applicable to the inter-terminal communication of the licensed band. In this case, the length of a frame to be used and the length of a sub-frame constituting a frame can be designed to be the same. In addition, it can be shown that the system can be designed to be advantageous for handover, searching, and interworking by synchronizing the time synchronization of the system used for two different purposes.

First Embodiment

The present embodiment proposes a method characterized in that a transmission period of a synchronizing signal to be transmitted is varied depending on the use purpose of the communication system. In the current LTE system, a synchronization signal is transmitted every frame (10 ms). This can lead to excessive power consumption when there is no data to transmit, and may cause excessive interference to neighboring nodes.

5 is a diagram illustrating a case where the transmission period of the synchronization signal according to another embodiment of the present invention is set differently.

The synchronization signal received from the first cell according to the first exemplary embodiment of the present invention may be periodically received at a predetermined radio frame interval.

Referring to FIG. 5, the synchronization signal received from the first cell (first frequency band) may be set to have a different transmission period from the synchronization signal received from the second cell. That is, the first cell can intermittently transmit the synchronization signal at a preset cycle. That is, the synchronization signal transmission period can be set so that the radio frame 500 including the synchronization signal and the radio frame 550 not including the synchronization signal exist. On the other hand, the second cell can transmit the synchronization signal in all the radio frames as in the synchronous signal transmission of the conventional mobile communication. Accordingly, when a synchronization signal is periodically received, the UE can quickly confirm that the cell or the frequency band is the first cell or the first frequency band.

In other words, in the mobile communication base station in the license band, a synchronization signal is transmitted every radio frame. However, in the case of operating in a license-exempt band as a wireless LAN, a synchronization signal is transmitted only to some wireless frames. That is, a synchronization signal is transmitted only once for every N radio frames. In Fig. 5, the case of 3 is shown. That is, the mobile communication base station used in the license band always transmits a synchronization signal for every radio frame. On the other hand, in the case of a system used in a license-exempt band, a synchronization signal can be transmitted only to one radio frame every three. This can reduce interference to adjacent nodes and reduce the waste of power consumption. In the case of FIG. 5, it is assumed that the apparatus operates in two different modes with different settings under the same standard.

It is also shown in FIG. 5 that the case of transmitting a synchronization signal to only some of the radio frames can be applied to a case where a terminal transmits a synchronization signal like a terminal-to-terminal communication (D2D communication) in a license band. In this case, it is possible to reduce the power consumption of the host (host terminal) in the inter-terminal communication by transmitting the synchronous signal only at the predetermined time in synchronism with the transmission time of the base station in the license band. At the same time, other terminals participating in the inter-terminal communication can also perform a search only at a predefined time to confirm whether there is a synchronization or a neighboring terminal. When the transmission frequency of the synchronization signal transmitted by the base station in the license band is different from the transmission frequency of the synchronization signal transmitted by the system in the license-unlicensed band (or the terminal in the license band), the synchronization signal shape may be implemented in various forms.

Second Embodiment

The resource allocation pattern of the synchronization signal may be set differently according to another embodiment of the present invention.

6 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.

The synchronization signal received from the first cell according to another embodiment of the present invention may be received in only one subframe in one radio frame.

Referring to FIG. 6, the synchronization signal transmitted in the first cell may be received in only one subframe 600 within one radio frame. On the other hand, the synchronization signal transmitted in the second cell may be received in two subframes 610 and 615 in one radio frame. That is, the number of subframes received in one radio frame may be different from that of a synchronization signal received in the first cell and a synchronization signal received in the second cell. The terminal can detect any type of system (or cell) at the time of initial acquisition due to transmission of different types of synchronous signals. In this case, the synchronization signal can be transmitted and received by allocating resources to the last symbol of the first slot in one subframe. Or may be allocated to another resource block and transmitted and received.

7 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.

Referring to FIG. 7, the synchronization signal received from the first cell may be received in one subframe 700 only. The synchronization signal received from the second cell may be received in two subframes 710 and 715. In this case, however, unlike FIG. 6, the synchronization signal received from the first cell may receive two synchronization signals in one subframe 700. That is, the SSS and the PSS can be received twice repeatedly. Through this, the terminal can synchronize with the base station. That is, two SSSs and two PSSs are received in one radio frame as in the conventional synchronous signal, and in the first frequency band, they can be received in one subframe. In this way, not only the power consumed in transmission can be reduced, but also interference to adjacent nodes can be minimized. The terminals detect the transmission mode of the synchronous signal and know in what mode (or frequency band) the cell operates.

Third Embodiment

A case where a resource allocation position of a synchronization signal is set differently according to another embodiment of the present invention will be described.

8 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.

A synchronization signal received from a first cell according to another embodiment of the present invention is received in two subframes in one radio frame, and the two subframe intervals include a synchronization signal received from the second cell, Lt; / RTI > may be set to be different from the subframe interval of FIG.

Referring to FIG. 8, a synchronization signal received from a first cell may be received in two subframes 800 and 809 in one radio frame. In addition, the synchronization signal received from the second cell may be received in two sub-frames 810 and 815 in one radio frame. However, the resource allocation positions of the synchronization signals received from the first cell and the second cell may be set to be different from each other. That is, as shown in FIG. 8, a synchronization signal resource can be allocated to the 0th subframe 800 and the 3th subframe 809 in the case of the first cell, and to the 0th subframe 810 in the case of the second cell. And a resource of a synchronization signal may be allocated to the fifth sub-frame 815. [

Accordingly, the UE can confirm the frequency band or the cell by checking the inter-frame interval of the synchronization signal allocated in one radio frame. In FIG. 8, the subframe interval of the first cell is set to 3, but the present invention is not limited thereto. The subframe interval is set to be different from the second cell.

Fourth Embodiment

In another embodiment of the present invention, a case where a subframe number to which a synchronization signal is allocated is set differently will be described.

9 is a diagram illustrating a case where a transmission pattern of a sync signal according to another embodiment of the present invention is set differently.

The synchronization signal received from the first cell according to another exemplary embodiment of the present invention is received in two subframes within one radio frame and the two subframe intervals include the subframe of the synchronization signal received from the second cell The two subframe numbers may be set to be different from the subframe number of the synchronization signal received from the second cell.

Referring to FIG. 9, all the synchronization signals received from the first cell and the second cell may be received in two subframes within one radio frame. However, the synchronization signal received from the first cell may be set to be different from the subframe number of the synchronization signal received in the second cell.

For example, the synchronization signal received from the first cell may be received in the 2 nd sub-frame 900 and the 7th sub-frame 909, and the synchronization signal received from the 2 nd cell may be received from the 0th cell 910 and 5 (915) < / RTI > subframe. As another example, the synchronization signal received from the first cell may be received in the first and sixth subframes. The subframe number is described as an example, and the synchronization signal received from the first cell and the second cell is set such that two synchronization signals are set to subframes with the same interval, and the start subframe thereof can be set differently.

Each of the embodiments described above may be applied individually, or a combination of two or more embodiments may be used to set a synchronization signal. For example, a synchronization signal received from a first cell may be received only in a certain period of a radio frame having a certain transmission period, and may be received in only one sub-frame in a radio frame in which a synchronization signal is received. As described above, the first embodiment and the fourth embodiment described above can be combined with each other to configure the synchronization signal setting method of the present invention.

10 is a view for explaining an operation of a base station according to another embodiment of the present invention.

According to another aspect of the present invention, there is provided a method of transmitting a synchronization signal, the method comprising: setting a transmission pattern of a synchronization signal according to which frequency band of the first frequency band or the second frequency band is transmitted And transmitting the synchronization signal using the transmission pattern of the synchronization signal through any one of the first cell using the first frequency band and the second cell using the second frequency band.

Referring to FIG. 10, the base station may include a step of setting a transmission pattern of a synchronization signal according to which frequency band of the first frequency band or the second frequency band is transmitted (S1010). For example, the base station can set the synchronization signal differently according to a predetermined use of the frequency band in which the synchronization signal is transmitted.

In addition, the first frequency band and the second frequency band may be classified according to the use of a predetermined frequency band. For example, any one of the first frequency band and the second frequency band may be preset for use for inter-terminal communication or wireless LAN communication.

The transmission pattern may be set differently according to the methods of the first to fourth embodiments described above. For example, a synchronization signal transmitted in a first cell using a first frequency band and a synchronization signal transmitted in a second cell using a second frequency band may be different from one another in that at least one of a transmission period, . ≪ / RTI > As another example, the synchronization signal transmitted in the first cell may be set to be periodically transmitted at a predetermined radio frame interval. As another example, the synchronization signal transmitted in the first cell may be set to be transmitted in only one subframe in one radio frame. As another example, the synchronization signal transmitted in the first cell is transmitted in two subframes within one radio frame, and the two subframe intervals are set to be different from the subframe intervals of the synchronization signal transmitted from the second cell . As another example, the synchronization signal transmitted in the first cell is transmitted in two subframes within one radio frame, and the two subframe intervals are set equal to the subframe intervals of the synchronization signal transmitted from the second cell , The two subframe numbers may be set different from the subframe number of the sync signal transmitted from the second cell.

In addition, a transmission pattern can be set by various methods that are the same as the reception pattern of the terminal described above.

The base station may include a step of transmitting a synchronization signal using a transmission pattern of a synchronization signal through any one of a first cell using a first frequency band and a second cell using a second frequency band (S1020). For example, a base station may constitute one or more cells, and each cell may use a different frequency band. The synchronization signal set in accordance with the transmission pattern described above can be transmitted to the terminal according to the frequency band.

A configuration of a terminal and a base station capable of performing all of the methods of the present invention described with reference to Figs. 1 to 10 will be described.

11 is a diagram illustrating a configuration of a terminal according to another embodiment of the present invention.

The terminal 1100 receiving the synchronization signal according to another embodiment of the present invention receives the synchronization signal from any one of the first cell using the first frequency band and the second cell using the second frequency band And a controller 1110 that determines which of the first frequency band and the second frequency band the synchronization signal is received based on the reception unit 1130 and the reception pattern of the synchronization signal.

Referring to FIG. 11, the receiver 1130 of the present invention can receive a synchronization signal from any one of a first cell using a first frequency band and a second cell using a second frequency band. In addition, the receiving unit 1130 receives downlink control information, data, and messages from the other terminal through the corresponding channel in the base station or inter-terminal communication.

The control unit 1110 can determine which frequency band of the first frequency band and the second frequency band the synchronization signal is received based on the reception pattern of the synchronization signal. In addition, the controller 1110 receives the synchronization signal required to perform the above-described present invention, and controls the overall operation of the terminal to distinguish the license band from the license-exempt band based on the reception pattern of the synchronization signal.

The transmitter 1120 may transmit uplink control information, data, and a message to the base station or the other terminal through the corresponding channel.

12 is a diagram illustrating an exemplary terminal configuration operation according to another embodiment of the present invention.

The UE of the present invention can acquire synchronization with the PSS using the system using the correlation value for the PSS. For example, when power of the initial terminal is turned on, a correlation value for each different transmission number is input to calculate a correlation value for PSS. A correlation value is calculated in accordance with the first transmission number and the second transmission number for a predetermined period, and these correlation values are input to the comparison / The comparing / comparing unit 1200 compares the two values to finally determine whether the PSS synchronization is obtained and the use of the system to be used.

As another example, the terminal may attempt to acquire initial information utilizing both PSS and SSS information. When the UE is powered on, it first attempts to acquire the PSS and proceeds to a correlation value for one PSS transmission. The comparator / determiner 1200 calculates a correlation value for all of the values of the PSS and the SSS using the obtained information to obtain an approximate synchronization and then assuming the first transmission number and the second transmission number, To obtain the final synchronization.

As another example, it is shown that after acquisition of the PSS, the initial acquisition can be obtained only by the correlation value to the SSS.

13 is a view showing another example of terminal configuration operation according to another embodiment of the present invention.

Referring to FIG. 13, a UE includes a correlator 1301 for calculating a correlation value for PSS and a correlator 1302 for calculating a correlation value for SSS. The time controller 1303 controls the time at which this correlation value is calculated. In the terminal structure of FIG. 13, since a synchronization signal is transmitted only to a specific frame, synchronization signal detection is performed only for a specific frame after the initial synchronization. Thus, the synchronous signal is not always detected, but the synchronous signal can be searched only at the time when the synchronous signal is transmitted. At this time, the determination unit 1300 can determine whether synchronization is present and whether a new node is detected with a correlation value for the calculated synchronization signals.

14 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

Referring to FIG. 14, a base station 1400 according to another embodiment of the present invention includes a controller 1410, a transmitter 1420, and a receiver 1430.

That is, the base station 1400 of the present invention includes a controller 1410 for setting a transmission pattern of a synchronization signal according to which frequency band of the first frequency band and the second frequency band is transmitted, And a transmitting unit 1420 that transmits a synchronization signal using a transmission pattern of a synchronization signal through any one of a first cell used and a second cell using a second frequency band.

The control unit 1410 can set the transmission pattern of the synchronization signal of the wireless communication system operating in the license band and the license-exempt band necessary for carrying out the present invention according to each of the above-described embodiments. In addition, the controller 1410 can control the operation of the base station, which is necessary to perform the operation of the base station, as a whole.

The transmission pattern can be set in the method according to the first to fourth embodiments described above.

The transmitting unit 1420 can transmit the synchronization signal using the transmission pattern of the synchronization signal through any one of the first cell using the first frequency band and the second cell using the second frequency band. In addition, the transmitter 1420 transmits downlink control information, data, and messages to other terminals in a terminal or inter-terminal communication through a corresponding channel.

The receiving unit 1430 can receive uplink control information, data, and messages from other terminals through a corresponding channel in a terminal or terminal communication.

In the above description, the case where the base station transmits the synchronization signal using different frequency bands has been exemplified. However, as another example, the base station may use the licensed band frequency band, and the wireless LAN or the inter-terminal communication may be applied to the case where the wireless LAN license-exempt band frequency band is used. That is, the above-described embodiments of the present invention can be applied to a case where a base station transmits a synchronization signal in a second frequency band and a host terminal transmits a synchronization signal in a first frequency band in a wireless LAN AP or inter-terminal communication. That is, the terminal can distinguish whether the synchronization signal is transmitted from the base station or transmitted from the wireless LAN AP (or the host terminal) by using the reception pattern of the synchronization signal. That is, the reception pattern of the synchronization signal transmitted from the wireless LAN AP (or the host terminal) may be set in the same manner as in the first to fourth embodiments.

The present invention described above proposes a method for using the wireless LAN in a license-exempt band such as a wireless LAN by slightly changing the physical layer structure of the mobile communication system. Particularly, in a mobile communication system, a synchronization signal is transmitted every frame. However, this may cause unnecessary interference to adjacent nodes when applied in a license-exempt band, and may cause a lot of power consumption in transmission. Therefore, according to the present invention, a synchronization signal is transmitted only to a specific frame according to an operation mode. When the synchronization signal is used for the same purpose as a base station of a license band, a synchronization signal is transmitted every frame. Frame is transmitted only to the frame. This not only reduces interference to neighboring nodes in the license-exempt band, but also reduces the power consumed in transmission.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (19)

A method for a terminal to receive a synchronization signal,
The method comprising: receiving a synchronization signal from any one of a first cell using a first frequency band and a second cell using a second frequency band; And
And determining which of the first frequency band and the second frequency band the synchronization signal has been received based on the reception pattern of the synchronization signal. The method according to claim 1,
Wherein the first frequency band and the second frequency band comprise:
Wherein the frequency band is divided according to a use of a preset frequency band. 3. The method of claim 2,
Wherein one of the first frequency band and the second frequency band includes a first frequency band,
Wherein the communication is pre-set for use for inter-terminal communication or wireless LAN communication. The method according to claim 1,
The synchronizing signal includes:
A Primary Synchronization Signal (PSS), and a Secondary Synchronization Signal (SSS). The method according to claim 1,
Wherein the synchronization signal transmitted in the first cell using the first frequency band and the synchronization signal transmitted in the second cell using the second frequency band are synchronized with each other,
Wherein at least one of a transmission period, a transmission period and a resource allocation pattern is set differently. The method according to claim 1,
Wherein the synchronization signal received from the first cell comprises:
And is periodically received at a preset radio frame interval. The method according to claim 1,
Wherein the synchronization signal received from the first cell comprises:
Characterized in that it is received in only one sub-frame within one radio frame. The method according to claim 1,
Wherein the synchronization signal received from the first cell comprises:
Wherein the two subframe intervals are received in two subframes within one radio frame and the two subframe intervals are set different from the subframe intervals of the synchronization signals received from the second cell. The method according to claim 1,
Wherein the synchronization signal received from the first cell comprises:
The two subframe intervals are set to be the same as the subframe intervals of the synchronization signal received from the second cell,
Wherein the two subframe numbers are set different from the subframe number of the synchronization signal received from the second cell. A method for a base station to transmit a synchronization signal,
Setting a transmission pattern of the synchronization signal according to which frequency band of the first frequency band and the second frequency band is transmitted; And
And transmitting the synchronization signal using a transmission pattern of the synchronization signal through a first cell using the first frequency band and a second cell using the second frequency band . 11. The method of claim 10,
Wherein the first frequency band and the second frequency band comprise:
Wherein the frequency band is divided according to a use of a preset frequency band. 12. The method of claim 11,
Wherein one of the first frequency band and the second frequency band includes a first frequency band,
Wherein the communication is pre-set for use for inter-terminal communication or wireless LAN communication. 11. The method of claim 10,
Wherein the synchronization signal transmitted in the first cell using the first frequency band and the synchronization signal transmitted in the second cell using the second frequency band are synchronized with each other,
Wherein at least one of a transmission period, a transmission period and a resource allocation pattern is set differently. 11. The method of claim 10,
Wherein the synchronization signal transmitted in the first cell includes:
And is periodically transmitted at predetermined radio frame intervals. 11. The method of claim 10,
Wherein the synchronization signal transmitted in the first cell includes:
And only in one subframe within one radio frame. 11. The method of claim 10,
Wherein the synchronization signal transmitted in the first cell includes:
Wherein the two subframe intervals are transmitted in two subframes within one radio frame, and the two subframe intervals are set to be different from the subframe intervals of the synchronization signal transmitted from the second cell. 11. The method of claim 10,
Wherein the synchronization signal transmitted in the first cell includes:
The two subframe intervals are set to be equal to the subframe intervals of the synchronization signal transmitted from the second cell,
Wherein the two subframe numbers are set different from the subframe number of the synchronization signal transmitted from the second cell. In a terminal that receives a synchronization signal,
A receiver for receiving a synchronization signal from any one of a first cell using a first frequency band and a second cell using a second frequency band; And
And a control unit which determines which of the first frequency band and the second frequency band the synchronization signal is received based on the reception pattern of the synchronization signal. A base station for transmitting a synchronization signal,
A control unit for setting a transmission pattern of the synchronization signal according to which frequency band of the first frequency band or the second frequency band is transmitted; And
And a transmitter for transmitting the synchronization signal using a transmission pattern of the synchronization signal through one of a first cell using the first frequency band and a second cell using the second frequency band, .

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