KR20180049967A - Method and apparatus for transmitting and receiving synchronization signals in cellular communication system - Google Patents

Abstract

The present invention relates to a 5G or a pre-5G communication system to support a higher data transmission rate than a 4G communication system such as LTE. The present invention relates to a wireless communication system and, more specifically, to a method and a system which efficiently perform initial synchronization if a plurality of sub-carrier interval values are supported to satisfy various requirements and operating scenarios required by next generation mobile communication in a single integrated system. According to an embodiment of the present invention, a signal transmission method for initial connection of a terminal comprises: a step of mapping a synchronization signal needed in system operation, a master information block (MIB), and a system information block (SIB) to a preset identical frequency domain; and a step of transmitting the mapped information.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a synchronous signal transmission and reception method for a cellular communication system,

The present invention relates to a wireless communication system, and more particularly, to a wireless communication system, in which a plurality of subcarrier interval values are supported to satisfy various requirements and operating scenarios required in a next generation mobile communication in one integrated system, And to a system and method for performing the same.

Efforts are underway to develop an improved 5G or pre-5G communication system to meet the growing demand for wireless data traffic after commercialization of the 4G communication system. For this reason, a 5G communication system or a pre-5G communication system is referred to as a 4G network (Beyond 4G Network) communication system or a post-LTE system (Post LTE) system.

To achieve a high data rate, 5G communication systems are being considered for implementation in very high frequency (mmWave) bands (e.g., 60 gigahertz (60GHz) bands). In order to mitigate the path loss of the radio wave in the very high frequency band and to increase the propagation distance of the radio wave, in the 5G communication system, beamforming, massive MIMO, full-dimension MIMO (FD-MIMO ), Array antennas, analog beam-forming, and large scale antenna technologies are being discussed.

In order to improve the network of the system, the 5G communication system has developed an advanced small cell, an advanced small cell, a cloud radio access network (cloud RAN), an ultra-dense network, (D2D), a wireless backhaul, a moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Have been developed.

In addition, in the 5G system, the Advanced Coding Modulation (ACM) scheme, Hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), the advanced connection technology, Filter Bank Multi Carrier (FBMC) (non-orthogonal multiple access), and SCMA (sparse code multiple access).

For example, 3GPP's High Speed Packet Access (HSPA), LTE (Long Term Evolution or Evolved Universal Terrestrial Radio Access (E-UTRA)), LTE-Advanced Which provides high-speed and high-quality packet data services such as LTE-A, LTE-Pro, High Rate Packet Data (HRPD) of 3GPP2, Ultra Mobile Broadband (UMB), and IEEE 802.16e Communication system.

In the LTE system, an OFDM (Orthogonal Frequency Division Multiplexing) scheme is used in a downlink (DL) and a Single Carrier Frequency Division Multiple (SC-FDMA) scheme is used in an uplink Access) method. The uplink refers to a radio link through which a UE (User Equipment) or an MS (Mobile Station) transmits data or control signals to a base station (eNode B or base station (BS) The term " wireless link " In the above multiple access scheme, the data or control information of each user is classified and operated so that the time and frequency resources for transmitting data or control information for each user do not overlap each other, that is, orthogonality is established. do.

5G wireless cellular communication system ^{(5 th Generation Wireless Cellular Communication System} : 5G Communication System) In order to satisfy various requirements and service of a user for support a range of services with different transmission and reception method, transmission and reception parameters in a system Do. In addition, the 5G communication system should be able to provide future compatibility so that new communication services and applications to be provided in the future will not be constrained according to the design specifications of the current system. Based on these 5G design requirements, it is necessary to provide a single and efficient initial access scheme for terminals supporting different transmission / reception schemes and transmission / reception parameters. Also, in consideration of compatibility in the future, it is necessary to design an initial access signal so that future compatibility is not limited by signal transmission for initial connection.

A method according to an embodiment of the present invention is a signal transmission method for initial connection of a terminal. The method includes a synchronization information signal, a master information block (MIB), and a system information block (SIB) To a same preset frequency domain; And transmitting the mapped information.

The present invention supports different transmission / reception schemes, services having transmission / reception parameters, and can efficiently perform initial connection in a 5G system designed in consideration of future compatibility.

1 is a diagram showing an example of allocation of resources when services to be considered in the 5G communication system are transmitted to one system.
FIGS. 2A and 2B are views showing examples of using different subcarrier intervals in a 5G communication system using OFDM.
3 is a diagram illustrating a case where a time-frequency resource region of a 5G communication system is allocated for future services in order to consider future compatibility in a 5G communication system.
FIG. 4 is a flowchart illustrating an initial connection of a terminal according to a first embodiment of the present invention in a future 5G communication system.
5 is a diagram illustrating an example in which a sync signal having a different subcarrier interval is transmitted according to a frequency position at which a sync signal can be transmitted according to the second embodiment of the present invention.
6A and 6B are diagrams illustrating time domain multiplexing and frequency domain multiplexing, respectively, which are considered for synchronous signal transmission.
7 is a functional block diagram of a base station transmitting unit according to the present invention.
8 is a functional block diagram of a terminal receiver according to the present invention.

Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. It should be noted that the drawings of the present invention attached hereto are provided for the purpose of helping understanding of the present invention, and the present invention is not limited to the shape or arrangement exemplified in the drawings of the present invention. Further, the detailed description of well-known functions and constructions that may obscure the gist of the present invention will be omitted. In the following description, only parts necessary for understanding the operation according to various embodiments of the present invention will be described, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

Hereinafter, a future communication system after LTE, i.e., a 5G communication system, will be described. 5G communication system should be able to reflect various requirements such as user and service provider freely, so that a service satisfying various requirements should be supported. The services considered for the 5G communication system include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra reliable low latency communication (URLLC) .

eMBB aims to provide a higher data transfer rate than the data rates supported by traditional LTE, LTE-A or LTE-Pro. For example, in a 5G communication system, an eMBB should be capable of providing a peak transmission rate of 20 Gbps in the downlink and a maximum transmission rate of 10 Gbps in the uplink in view of one base station. At the same time, an increased perceived data rate of the terminal must be provided. In order to satisfy such requirements, improvement of the transmission / reception technology is demanded including a further improved multi-input multi-output (MIMO) transmission technique. Also, instead of the 2GHz band used by the current LTE, the bandwidth of 3 ~ 6GHz or more than 20MHz in the frequency band of 6GHz or more can be used to satisfy the data transmission speed required in the 5G communication system.

At the same time, mMTC is considered to support application services such as Internet of Thing (IoT) in 5G communication systems. In order to efficiently provide Internet of things, mMTC is required to support connection of large terminals in a cell, enhancement of terminal coverage, improved battery time, and cost reduction of terminals. Object The Internet must be able to support a large number of terminals (for example, 1,000,000 terminals / km2) in a cell because it is attached to various sensors and various devices and provides communication functions. In addition, terminals supporting mMTC are more likely to be located in shaded areas that can not be covered by a cell, such as a building underground, due to the nature of the service, thus requiring a wider coverage than other services provided by the 5G communication system. Terminals supporting mMTC should be configured as inexpensive terminals and very long battery life time is required because it is difficult to exchange the terminals' batteries frequently.

Finally, in the case of URLLC, cellular-based wireless communication services used for mission-critical purposes include remote control for robots or machinery, industrial automation, Unmanaged Aerial Vehicle, Remote Health Care, Emergency Alert, etc., should provide communications that provide ultra-low latency and ultra-high reliability. For example, a service that supports URLLC must meet Air interface latency of less than 0.5 milliseconds and at the same time have a packet error rate of less than 10 ^-5 . Therefore, for a service that supports URLLC, the 5G system must provide a smaller transmission time interval (TTI) than other services, and at the same time, a design requirement for allocating a wide resource in the frequency band is required.

The services to be considered in the above-mentioned 5G communication system should be fused to each other based on a single framework. That is, for efficient resource management and control, it is preferable that each service is integrated and controlled and transmitted to one system rather than operating independently.

1 is a diagram showing an example of allocation of resources when services to be considered in the 5G communication system are transmitted to one system.

In FIG. 1, a resource (hereinafter referred to as a resource) defined in the frequency-time axis used by the 5G communication system can be mapped to a frequency axis and a time axis. The resources mapped on the frequency-time axis are configured in a plurality of resource blocks (RB) units on the frequency axis and consist of consecutive subframes on the time axis. Here, RB denotes a minimum unit of scheduling in a frequency domain composed of a plurality of subcarriers constituting OFDM similar to LTE. Here, the term " subframe " refers to a minimum unit of scheduling in a time domain composed of a plurality of OFDM symbols similar to LTE. 1 illustrates that the 5G communication system operates frequency and time resources required for eMBB 104, mMTC 105, and URLLC 106 within a single framework.

Also, an enhanced Mobile Broadcast / Multicast Service (eMBMS) 107 for providing a broadcasting service on a cellular basis may be considered as a service that can be additionally considered in the 5G communication system. services considered in the 5G communication system such as eMBB, mMTC, URLLC, and eMBMS can be classified into Time Division Multiplexing (TDM) or Frequency Division Multiplexing (FDM) within a single system frequency bandwidth operated by the 5G communication system. ), And spatial division multiplexing (Spatial Division Multiplexing) may also be considered.

In the case of the eMBB 104, it is preferable to occupy and transmit a maximum frequency bandwidth at a specific arbitrary time in order to provide the above-mentioned increased data transmission rate. That is, it is desirable to allocate as many RB as possible to transmit data to the terminal. Accordingly, in the case of the eMBB 104 service, it is preferable that the e-MBB 104 is transmitted in TDM within a frequency-time resource provided by other services and systems. However, according to the needs of other services, FDM may be considered.

In the case of the mMTC 105, an increased transmission interval is required to secure wide coverage unlike other services, and coverage can be ensured by repetitively transmitting the same packet within the transmission interval. At the same time, in order to reduce the complexity of the terminal and the terminal price, the transmission bandwidth that the terminal can receive is limited. Considering this requirement, the mMTC 105 is preferably transmitted in FDM with other services within the frequency-time resource provided by the 5G communication system.

The URLLC 106 preferably has a short Transmit Time Interval (TTI) when compared to other services in order to meet the ultra low delay requirements required by the service. At the same time, since it is necessary to have a low coding rate in order to satisfy the second reliability requirement, it is preferable to have a wide bandwidth on the frequency side. In view of the requirements of such a URLLC 106, it is desirable that the URLLC 106 be TDM with other services within the frequency-time resource of the 5G communication system.

Each of the services described above may have different transmission / reception techniques and transmission / reception parameters to satisfy the requirements of the respective services. For example, each service may consider having a different numerology depending on each service requirement. Numerology refers to a method of calculating a Cyclic Prefix (CP) length and a subcarrier interval in an OFDM (Orthogonal Frequency Division Multiplexing) or an Orthogonal Frequency Division Multiple Access (OFDMA) spacing, OFDM symbol length, transmission interval length (TTI), and the like. As an example having different Numerologies between the above services, eMBMS 107 may have a longer CP length than other services. Since the eMBMS 107 transmits the broadcast-based upper traffic, the same data can be transmitted from all the cells. At this time, if a signal received from a plurality of cells reaches within a CP length, the UE can receive and decode all of the signals, so that a single frequency network diversity (SFN diversity) gain can be obtained And the terminal located at the cell boundary can receive broadcast information without any restriction of the coverage.

However, in the 5G communication system, when the CP length is relatively long in supporting the eMBMS 107, waste due to the CP overhead occurs. At the same time, a longer OFDM symbol length is required than other services, It requires a narrower subcarrier interval than other services.

Also, as an example in which different Numerologies are used between services in a 5G communication system, in the case of URLLC 106, a shorter OFDM symbol length may be required as a smaller TTI is required compared to other services, You can ask for an interval.

As described above, due to different requirements for each service, the 5G communication system must support a plurality of subcarrier intervals for transmission of physical signals and physical channels. At the same time, it is advantageous to use various subcarrier intervals in terms of initial synchronization signal transmission.

FIGS. 2A and 2B are views showing examples of using different subcarrier intervals in a 5G communication system using OFDM.

FIG. 2A illustrates a structure of subcarriers constituting OFDM in a time-frequency axis when a 15 kHz subcarrier interval is used, and FIG. 2B illustrates a structure of OFDM in a time-frequency axis in the case of a 30 kHz subcarrier interval Fig. 8 is a diagram showing the structure of subcarriers. 2A and 2B, in the case of FIG. 2A having a 15 kHz subcarrier interval, the interval 204 of one subcarrier 203 corresponds to one subcarrier having a 30 kHz subcarrier interval as shown in FIG. Occupies a frequency that is 1/2 times smaller than the interval 207 of the carrier 206. At the same time, the period 205 of the OFDM symbol with the 15 kHz subcarrier interval of FIG. 2A has a time period that is twice as long as the OFDM symbol period 208 with the 30 kHz subcarrier interval of FIG. 2B.

As shown in FIG. 2B, when the subcarrier interval of the synchronous signal is wide, there is an advantage that it is robust against the frequency offset and the Doppler effect in the process of cell search of the terminal. Also, when the subcarrier interval is wide in the small cell situation, the time period of the synchronous signal can be shortened and the resource overhead can be kept small. On the other hand, if the subcarrier interval of the synchronous signal is narrow as shown in FIG. 2A, since the period of the OFDM symbol constituting the synchronous signal is long, the transmission power for synchronous signal transmission can be further used, . Further, the subcarrier interval of the synchronous signal may be determined according to the subcarrier interval used for data transmission within the same system transmission bandwidth.

On the other hand, when another subcarrier interval is used in one OFDM system, the base station needs to additionally implement analog and digital filters in order to minimize mutual interference caused by using different subcarrier intervals between the synchronization signal and data . There is also a requirement to implement a plurality of Inverse Fast Fourier Transforms (IFFTs) for signal generation. Therefore, it may be advantageous to use the same subcarrier interval as the data subcarrier for the synchronization signal transmission. Therefore, in the present invention, it is assumed that the interval of the subcarriers of the synchronization signal can be determined appropriately according to the operating state of the base station, and a technology required therefor is proposed.

In order to satisfy various requirements of the 5G communication system, the necessity of various services is described and the requirements for the services being considered are described. At the same time, in the 5G communication system, technologies for forward compatibility should be considered in order to provide additional services in the future. The lack of consideration of future compatibility in the initial LTE standardization phase can create constraints in providing new services within the LTE framework. For example, in the case of eMTC (Enhanced Machine Type Communication) applied in LTE release-13, in order to reduce the terminal cost by reducing the complexity of the terminal, the system transmission bandwidth provided by the serving cell Regardless, it is possible to communicate only at frequencies corresponding to 1.4MHz. Therefore, the UE supporting the eMTC can not receive the physical downlink control channel (PDCCH) transmitted in the entire bandwidth of the system transmission bandwidth. Therefore, in the time interval during which the PDCCH is transmitted, Constraints that can not be received occurred. Therefore, a 5G communication system must be designed so that the services under consideration after the 5G communication system operate with efficient coexistence with the 5G communication system. For future compatibility in the 5G communication system, it is necessary to freely allocate and transmit resource resources so that services to be considered in future can be freely transmitted in the time-frequency resource region supported by the 5G communication system.

3 is a diagram illustrating a case where a time-frequency resource region of a 5G communication system is allocated for future services in order to consider future compatibility in a 5G communication system.

In FIG. 3, the time-frequency resource areas 301 for the 5G communication system can be mapped within a single radio frame 302 and the system transmission bandwidth 303 supported by the 5G communication system. A plurality of transmission time periods (TTI, 304), which is a basic transmission unit for transmitting one packet, may exist within one radio frame 302. In the present invention, for example, ten TTIs (304) are present. As illustrated in FIG. 3, for compatibility with future services, it is possible to consider TDM-based resource allocation or FDM-based resource allocation for future services. In FIG. 3, the specific TTIs 305 and 306 illustrate a method of allocating for a future service in a TDM manner. Also, in FIG. 3, a specific frequency resource 307 is allocated for future services in an FDM manner. Although not shown in FIG. 3, in the 5G communication system, resource resources configured by a combination of TDM / FDM may be allocated for future services. In other words, future services can allocate resources to use only limited resources in both time and frequency domain. In FIG. 3, the TDM time resources 305 and 306 are allocated to services to be considered in the future, and the TDM service coexists with the other services currently provided by the 5G communication system. And is considered as a method suitable for a service requiring a data transmission rate and a low transmission delay time.

In FIG. 3, a frequency resource 307 of the FDM scheme is allocated to a service to be considered in the future, and a method of coexistence with other services currently provided by the 5G communication system is called a narrowband narrow- When transmission is required, when the requirements for transmission delay are relatively insensitive, when relatively large coverage is required, when it is required to last a low data rate but when seamless communication resources are required. .

In the case of multiplexing by the FDM between the service to be considered in the future and the existing service in the 5G communication system, the following considerations should be considered.

First, in a 5G communication system, when there is a physical channel transmitted to all bands, or a reference signal transmitted through channel equalization or synchronization, it is difficult to multiplex FDM-based services between services to be considered in the future and existing services. For example, a cell-specific reference signal (CRS) or a physical downlink control signal transmitted for channel equalization or synchronization as an example of a signal transmitted in all bands for each transmission unit in the current LTE have. Since such a signal is always transmitted to all bands and the terminal performs basic operations such as channel equalization, synchronization, and uplink and downlink scheduling through the signal, the LTE does not transmit such a signal or a physical channel, It is difficult to use it for other purposes separately. Therefore, in the 5G communication system, all physical channels and reference signals can be considered to be transmitted only in an arbitrary frequency band without using the entire band.

Second, the possibility that a service considered for future service in a 5G communication system overlaps with a signal or a physical channel necessary for system operation may be appreciated. That is, when a frequency resource for a future service is allocated, a synchronization signal, a master information block (MIB), and a system information block (SIB) transmitted for cell search, synchronization, ) May overlap with each other. For example, when synchronous signals, MIBs, and SIBs are fixedly transmitted in a certain frequency region (six resource blocks located in the middle of the system transmission bandwidth in LTE) corresponding to the middle of the system transmission bandwidth, as in the LTE system, Compatibility with future services can not be considered in the frequency resource. That is, the service considered after the 5G communication system can not transmit in the frequency resource located in the middle of the system transmission bandwidth. In other words, if a synchronous signal, a master information block (MIB), and a system information block (SIB) necessary for system operation are used in a 5G communication system similar to LTE, frequency resources fixed within the system transmission bandwidth are used. There will be restrictions in terms of compatibility in the future.

As described above, the present invention proposes an efficient initial connection process in designing a 5G communication system that satisfies various requirements and provides compatibility in the future.

In detail, in order to satisfy various requirements in a 5G communication system, when each service has different numerical values and transmission parameters, a physical channel and signal structure and procedure necessary for initial connection will be proposed.

In addition, considering the more flexible compatibility with future services in 5G communication system, we will propose the structure and procedure of physical and signal necessary for initial connection.

≪ Embodiment 1 >

In the first embodiment, in order to consider the compatibility with future services more freely in the 5G communication system, it is necessary to efficiently perform the initial connection in order to avoid the case where the compatibility is restricted in the future by the common signal required for system operation provided in the 5G communication system A signal transmission method and structure are proposed. Here, the common signal required for system operation may mean a synchronization signal required for the UE to perform time and frequency synchronization with respect to the base station, perform cell search, and an MIB or SIB for obtaining important information on the system.

In the present invention, the synchronization signal, the MIB, and the SIB necessary for system operation are transmitted in the same frequency band. When the synchronization signal, the MIB, and the SIB have the same frequency bandwidth, each signal can be transmitted in the same frequency domain. Also, even if the synchronization signal and the frequency bandwidth of the MIB and the SIB are different, the bandwidth of each signal should be positioned such that the centers of the bandwidth are equal to each other.

At the same time, a common signal such as synchronous signal, MIB, and SIB is added to the system transmission bandwidth such that the service considered by the additional service requirement after the 5G communication system is not constrained in future by the synchronous signal, the MIB, A method that can be set by the base station is proposed. That is, in the conventional LTE, in the case of the synchronous signal and the MIB, the transmission signal is always transmitted only within the transmission bandwidth of 1.4 MHz located in the middle of the transmission bandwidth of the system. However, in order to provide more flexibility in the future compatibility in the 5G communication system, So that it can exist at an arbitrary position within the transmission bandwidth. In order for the common signal to exist at an arbitrary position within the system transmission bandwidth, there must be a candidate set for the frequency position at which the common signal can be transmitted, and the base station may transmit the common signal Can be transmitted. Here, the common signal includes a signal for transmitting a synchronization signal MIB and a signal for transmitting a SIB, which all terminals must receive for initial connection. At this time, the frequency set to which the common signal can be transmitted can be determined from one resource block unit to a plurality of resource block units. Here, the resource block is a minimum unit for scheduling in the frequency domain, and can be composed of a plurality of subcarriers as in LTE. The location at which a common signal for such an initial connection can be transmitted may exist either absolutely or relatively within the system bandwidth. For example, if six resource blocks are required to transmit a common signal for initial connection and the base station is configured to transmit a common signal from the tenth resource block within the system transmission bandwidth, then the common signal is And may be transmitted within the transmission bandwidth corresponding to the 15th resource block from the 10th resource block.

As described above, when a resource block for transmitting a common signal exists at an arbitrary position within the system transmission bandwidth, unlike the existing LTE, additional information is required to transmit information on the system transmission bandwidth supported by the 5G communication system do. That is, in the case of the existing LTE, it can be assumed that the mobile station always transmits signals such as the synchronization signal (PSS / SSS) and the MIB to the center in the system transmission bandwidth. Therefore, if only information on the system transmission bandwidth informed by the MIB is acquired, the terminal can grasp all the settings for the system transmission bandwidth. That is, if the terminal knows only the size of the system transmission bandwidth, it can grasp both the start frequency and the end frequency of the system transmission band provided by the base station to which the terminal belongs.

However, as suggested in the first embodiment of the present invention, when the common signal for synchronization, cell search, and system information transmission is not transmitted at the center of the system transmission bandwidth, only the system transmission bandwidth information transmitted from the MIB All configurations of the transmission band can not be grasped. That is, unlike the existing LTE system, there is a problem that the start frequency and the end frequency of the system transmission band can not be known only by the size information of the system transmission bandwidth. In order to solve such a problem, in the first embodiment, a method of transmitting transmission position information of a common signal currently being transmitted through an MIB or SIB may be considered.

As a first method for transmitting the transmission position information of the common signal in the first embodiment of the present invention, a method of transmitting information corresponding to the frequency position at which the common signal is transmitted in the MIB may be considered. That is, in the MIB of the 5G communication system, it is possible to consider a method of transmitting the system transmission bandwidth and the position in the frequency domain in which the common signal is transmitted. At this time, the position in the frequency domain where the common signal is transmitted can be informed to the terminal at the center frequency of the bandwidth in which the offset or the common signal is transmitted. The size of the candidate set for the frequency offset or the center position of the transmission bandwidth over which the common signal can be transmitted may vary depending on the system transmission bandwidth supported by the 5G communication system. However, since the terminal can not know the system transmission bandwidth in the course of acquiring the MIB, the size of the candidate set for the frequency position at which the common signal can be transmitted can not be known. Therefore, the terminal must determine the size of the field for transmitting information on the frequency position of the common signal from the MIB, assuming the maximum system transmission bandwidth at all times. That is, the field for informing the frequency position where the common signal is transmitted to the MIB should always be determined according to the size of the frequency position candidate set of the determined common signal assuming the maximum system transmission bandwidth.

이라고 가정하면, 공통신호가 전송되는 주파수 위치를 알려주기 위한 필드는 해당 셀의 시스템 전송 대역폭과 관계없이 항상

의 값을 가져야 한다. 이때 만약 최대 시스템 전송 대역폭 보다 실제 시스템이 사용하는 전송 대역폭이 작을 경우 공통신호가 전송되는 주파수 위치를 알려주기 위한 필드에서 유효한 값은

보다 작으며, 나머지 값은 모두 0이 삽입될 수 있다. Let's take an example. And a system bandwidth of a communication system supporting 5G has N _RB of resource blocks, the size of the candidate set of the common signal frequency location in the system bandwidth of the resource block having N _RB

, The field for informing the frequency position at which the common signal is transmitted is always transmitted regardless of the system transmission bandwidth of the corresponding cell

. In this case, if the transmission bandwidth used by the real system is smaller than the maximum system transmission bandwidth, a valid value in the field for informing the frequency position where the common signal is transmitted

, And the remaining values can be all zeros.

As a second method for transmitting the transmission position information of the common signal in the first embodiment of the present invention, a method of transmitting the information in the SIB may be considered. That is, in the first embodiment of the present invention, a method of grasping a system transmission bandwidth through an MIB and locating a position in a frequency domain where a common signal being transmitted through the SIB is transmitted is proposed. At this time, the position in the frequency domain where the common signal is transmitted can be informed to the terminal at the center frequency of the bandwidth in which the offset or the common signal is transmitted. The size of the candidate set for the frequency offset or the center position of the transmission bandwidth over which the common signal can be transmitted may vary depending on the system transmission bandwidth supported by the 5G communication system. Unlike the first method of the first embodiment, since the terminal has already acquired information on the system transmission bandwidth through the MIB, the size of the field with respect to the center position of the transmission bandwidth inserted in the SIB can be determined according to the system transmission bandwidth have.

FIG. 4 is a flowchart illustrating an initial connection of a terminal according to a first embodiment of the present invention in a future 5G communication system.

Referring to FIG. 4, in step 401, the terminal moves the center frequency of the terminal to move to the first frequency among the frequency candidates to which the common signal can be transmitted. Here, the first frequency may be the lowest frequency in the entire system transmission bandwidth, may be the highest frequency, may be a preset specific frequency band, may select one of preset frequency bands, The transmission bandwidth may be divided (divided) by a preset reference and the divided bandwidth may be arbitrarily selected.

When the step 401 is completed, the terminal moves to step 402 and performs synchronization and cell search. If the UE does not satisfy all of the conditions for cell search completion in step 403 and the cell search is not completed or the cell search is not completed for a predetermined time, the UE proceeds to step 404 to transmit common signals Moves to the next frequency among the frequency candidates, and performs synchronization and cell search in step 402 again. If it is determined in step 403 that the mobile station satisfies all conditions for completing the cell search and cell search is performed, the mobile station moves to step 405. In step 405, the UE acquires information on the MIB in the same frequency band in which the cell search is completed. According to the first method of the first embodiment of the present invention, when there is a field for indicating the location of the frequency at which the common signal is transmitted in the MIB, consideration is given to the transmission frequency position of the common signal transmitted in the MIB and the size of the system transmission bandwidth The start and end frequencies of the system transmission band can be grasped.

If the SIB includes a field for informing the location of the frequency at which the common signal is transmitted according to the second method of the first embodiment of the present invention, the terminal transmits the system transmission bandwidth obtained in step 405 and the common signal obtained in step 406, The start frequency and the end frequency of the system transmission band can be grasped according to the position information of the frequency.

≪ Embodiment 2 >

The second embodiment of the present invention proposes a method and an apparatus for transmitting a synchronization signal of a base station for lowering the complexity of a mobile station when the synchronization signal is transmitted with different subcarrier intervals according to a base station operation situation or a used frequency band situation.

Since the terminal can not know the center frequency and the transmission bandwidth of the system band during the initial access process, the terminal attempts to detect a synchronization signal for initial connection at a certain frequency interval (frequency raster). When a synchronization signal is detected, the UE detects a cell ID and acquires system information from a broadcast channel that transmits the MIB based on the cell identifier. When the UE acquires the MIB information without error, the UE determines that the synchronization process is completed and can perform the random access process. If the synchronization signal can not be detected at the corresponding frequency position or the MIB information acquisition can not be completed, the synchronization signal is detected at the next frequency position according to the frequency interval.

As assumed in the present invention, when the base station determines the subcarrier interval of the synchronization signal in consideration of the operating state of the base station and the frequency band for the flexible operation of the base station, the terminal detects the synchronization signal, Lt; RTI ID = 0.0 > blind < / RTI > On the other hand, in the initial synchronization process, the increased blind detection number for detecting the subcarrier interval can increase the complexity of the UE. It is therefore desirable to minimize the blind detection of the terminal.

In order to solve such a problem, a second embodiment of the present invention proposes a method of mapping a position where a synchronization signal according to a center frequency can be transmitted and a subcarrier interval used for a synchronization signal. The frequency position at which the synchronization signal can be transmitted can be determined according to Equation (1) below.

In Equation (1), n represents an index of a position at which a synchronization signal can be transmitted, and F _raster represents a frequency _raster of a synchronization signal. Here, the frequency raster of the synchronization signal indicates an interval between positions where the synchronization signal can be transmitted in the frequency band. F _offset is a frequency offset value greater than 0 and less than F _raster . F _raster has a value of 100 kHz in LTE, but does not exclude that it has a larger value at 5 GHz. F _raster and F _offset are preset values between the UE and the BS, and are stored in advance in the software or hardware of the UE and the BS. In the present invention, it is proposed to use f (n) having a certain n value for transmission of a synchronous signal having a specific subcarrier interval. For example, a sync signal with a 15 kHz subcarrier interval is transmitted at f (n) with a value of n = 3 X k where k is an arbitrary integer, such as n = 0, 3, The synchronization signal having a 30 kHz subcarrier interval is transmitted in f (n) having a value of n = 3 X k +1 (where k is an arbitrary integer) such as n = 1, 4, 7, A synchronization signal having a 60 kHz subcarrier interval is transmitted at f (n) having a value of n = 3 X k + 2 (where k is an arbitrary integer) as n = 2, 5, 8, However, it is assumed that the base station transmits only one synchronization signal within one system bandwidth, and which subcarrier interval is used for the synchronization signal transmission can be determined by the base station according to the base station operation scenario and the position of the frequency band.

When the frequency position where the synchronization signal is transmitted and the subcarrier interval used by the synchronization signal are mapped to each other as described above, the terminal tries to detect a synchronization signal according to a predetermined frequency interval, and a specific subcarrier interval There is an advantage that blind detection is not required in the terminal. For example, if the UE attempts to detect at a frequency position f (n) determined by n = 0, 3, 6, and 9, the UE may assume that the synchronization signal is transmitted based on the 15 kHz subcarrier interval. Also, when the UE attempts to detect at a frequency position f (n) determined by n = 1, 4, 7, and 10, the UE can assume that the synchronization signal is transmitted based on the 30 kHz subcarrier interval. Finally, when the UE attempts to detect at a frequency position f (n) determined as n = 2, 5, 8, and 11, the UE can assume that the synchronization signal is transmitted based on the 60 kHz subcarrier interval.

5 is a diagram illustrating an example in which a sync signal having a different subcarrier interval is transmitted according to a frequency position at which a sync signal can be transmitted according to the second embodiment of the present invention.

In the system transmission bandwidth 501 given in FIG. 5, a plurality of candidate positions to which a synchronization signal can be transmitted are different from each other in frequency positions f (0) 502, f (1) 503, ... , f (8) (509). Here, f (0) (502), f (1) (503), ... , f (8) (5-09) can be defined according to the given F _raster , F _offset and Equation (1).

5, frequency positions f (0) 502, f (3) 505, and f (6) 508 corresponding to n = 0, 3 and 6, as an example according to the second embodiment of the present invention, ), A synchronization signal corresponding to a 15 kHz subcarrier interval can be transmitted. 5, frequency positions f (1) 503, f (4) 506, and f (7) 509 corresponding to n = 1, 4 and 7, as an example according to the second embodiment, A synchronization signal corresponding to a 30 kHz subcarrier interval can be transmitted. In FIG. 5, the synchronization signal can be configured not to be transmitted at all frequency positions according to f (n). The base station can determine the subcarrier interval of an appropriate synchronization signal according to the operating state of the base station or the center frequency, and can select a random value among the positions of the frequency positions f (n) mapped to subcarrier intervals of each synchronization signal, .

As in the second embodiment, when the base station transmits a synchronization signal having a specific subcarrier interval at a specific frequency, it is advantageous that the terminal does not need to detect the subcarrier interval of the synchronization signal in detecting the synchronization signal . That is, for example, when searching for a synchronization signal at a frequency position of f (2) 504, the terminal always detects a synchronization signal assuming that a synchronization signal defined by a 60-kHz sub-carrier interval is transmitted. If the terminal fails to detect the sync signal at f (2) 504, the terminal assumes a sync signal defined by the 15 kHz sub-carrier interval at the next frequency position f (3) according to Equation (1) . If a synchronization signal is detected at the corresponding location, the terminal then attempts to receive the same sync signal and broadcast information, assuming that the same subcarrier interval is used.

≪ Third Embodiment >

In the third embodiment of the present invention, when a plurality of synchronization signal multiplexing methods are used in one system and the terminal needs to know a synchronization signal multiplexing method used by the base station in the initial synchronization process, the synchronization signal of the base station We propose a transmission method.

6A and 6B are diagrams illustrating time domain multiplexing and frequency domain multiplexing, respectively, which are considered for synchronous signal transmission.

6A, a time-domain multiplexing scheme 601 of a synchronization signal includes a primary synchronization signal 602, a secondary synchronization signal 603, and a PBCH 604 for transmitting a MIB. Are transmitted at different times. That is, when the time division multiplexing scheme 601 is used as shown in FIG. 6A, the PSS 602, the SSS 603, and the PBCH 604 may be transmitted in different OFDM symbols. In FIG. 6A, the transmission of the synchronization signal based on the time domain multiplexing scheme 601 of the synchronization signal has an advantage that the synchronization signal can be transmitted even in the base station supporting the narrow transmission bandwidth. In addition, since all the transmission power available to the base station can be used for the synchronization signal in the time period during which the synchronization signal is transmitted, there is an advantage that the coverage of the synchronization signal can be increased.

6B illustrates a structure in which the PSS 606, the SSS 607, and the PBCH 608 constituting the synchronization signal are transmitted in different frequency resources according to the frequency domain multiplexing scheme 605 of the synchronization signal. That is, the PSS 606, the SSS 607, and the PBCH 608 may be transmitted in different resource blocks within the same OFDM symbol. 6B, there is a requirement that the transmission bandwidth of the base station must be large for the transmission of the synchronization signal based on the frequency-domain multiplexing scheme 605 of the synchronization signal. At the same time, since the PSS 606, the SSS 607, and the PBCH 608 must be transmitted simultaneously at the same time, the base station should share the available transmission power and use it. Thus, FIG. 6a, which is a time-domain multiplexing scheme in terms of coverage, has a small coverage. However, in the case of a millimeter wave-based communication system such as a band of 28 GHz or more, since the optical bandwidth can be used and the coverage can be increased by beam forming or the like, the problem of the frequency domain multiplexing method 605 Can be overcome. In case of millimeter wave based communication, beam-based synchronous signal is transmitted. A synchronization signal transmission based on beam sweeping is required to transmit a synchronization signal in all directions.

The beam-sweep-based synchronous signal transmission is a method of transmitting the same synchronous signal using different beams at specific time interval intervals. The frequency-domain multiplexing method 605 of FIG. 6B compared to the time- There is an advantage that overhead for signal transmission can be minimized.

Meanwhile, if the base station can selectively determine and transmit time-domain multiplexing and frequency-domain multiplexing of a synchronization signal according to a cell operation scenario and a beam-based transmission scheme, the mobile station transmits a synchronization signal in a certain multiplexing manner Should be detected. If the multiplexing method of the synchronous signal can be obtained based on the PSS which the terminal should first detect at the initial connection, blind detection of the PSS is required, which may increase the complexity of the terminal or cause performance deterioration. It is therefore desirable to minimize the blind detection of the terminal.

In order to solve such a problem, the present invention proposes a method of mapping a multiplexing method used for a synchronization signal and a position where a synchronization signal according to a center frequency can be transmitted. The frequency position at which the synchronization signal can be transmitted can be determined according to Equation (1) described above.

In the case of using Equation (1) described above, F _raster and F _offset are preset values between the UE and the BS, and are stored in advance in software or hardware of the UE and the BS. Also, in the present invention, it is proposed to transmit a synchronization signal using a specific multiplexing method for f (n) having a specific n value. For example, the synchronization signal transmitted using the time-domain multiplexing scheme is f (n) having a value of n = 2 X k (where k is an arbitrary integer) such as n = 0, 2, 4, 6, Lt; / RTI > The synchronization signal transmitted using the frequency domain multiplexing scheme is transmitted in f (n) having a value of n = 2 X k +1 (where k is an arbitrary integer) such as n = 1, 3, 5, . However, it is assumed that the base station transmits only one synchronization signal within one system bandwidth, and the base station can determine which multiplexing scheme to use for the synchronization signal transmission according to the base station operation scenario and the position of the frequency band.

When a frequency position at which a synchronization signal is transmitted is determined according to a multiplexing scheme in which a synchronization signal is transmitted, the terminal attempts to detect a synchronization signal according to a predetermined frequency interval, and a specific multiplexing method can be assumed at a specific frequency position Therefore, blind detection is not required in the terminal. For example, if the UE attempts to detect at a frequency position f (n) determined by n = 0, 2, 4, or 6, the UE assumes a synchronous signal transmitted based on the time domain multiplexing scheme and performs synchronization can do. Also, when the UE attempts to detect at a frequency position f (n) determined by n = 1, 3, 5, 7, the UE can assume that the synchronization signal is transmitted based on the frequency domain multiplexing scheme.

In order to perform the embodiments of the present invention described above, a transmitter of a base station and a receiver of a terminal will be described. FIG. 7 is a functional block diagram of a base station transmitter according to the present invention, and FIG. 8 is a functional block diagram of a terminal receiver according to the present invention.

According to the initial connection method and apparatus of the 5G communication system proposed in the above-described first, second, and third embodiments, the transmitter of the base station and the receiver of the terminal must operate.

First, the configuration and operation of the transmission unit of the base station will be described with reference to FIG. 7, the transmitter of the base station of the present invention includes resource mapping units 701, 704, and 707 for transmitting signals such as eMBB, mMTC, and common signals corresponding to respective services, 705 and 708 corresponding to the respective resource mapping units 701, 704 and 707 and the respective filters 703 corresponding to the respective OFDM modulating units 702, , 706, 709). Each of the resource mapping units 701, 704, and 707 performs QPSK / QAM modulation on the data to be transmitted and maps the data to a time-frequency domain resource. Each of the OFDM modulators 702, 705, and 708 performs OFDM modulation based on signals mapped in the respective resource mappers 701, 704, and 707. Wherein the OFDM modulation includes performing an IFFT and inserting a cyclic prefix before the OFDM symbol. Each of the filters 703, 706, and 709 performs filtering to satisfy a frequency band spectrum mask restriction of the signals generated by the OFDM modulators 702, 705, and 708 . A physical channel and a signal can be generated through the resource mapping units 701, 704 and 707 allocated to each service, the OFDM modulation units 702, 705 and 708, and the filters 703, 705 and 709 . For example, in order to transmit a physical channel and a signal for supporting the eMBB service, a physical channel for the eMBB through the resource mapping unit 701, the OFDM symbol modulating unit 702, and the filter 703 allocated to the eMBB transmission, Signal can be generated. At this time, the resource mapping unit 701, the OFDM symbol modulating unit 702, and the filter 703 can generate a physical channel and a signal using a numeric value defined for the eMBB.

Similarly, the common signal includes signals for synchronization and system information acquisition of the UE and is allocated for common signals through a resource mapping unit 707, an OFDM symbol modulation unit 708, a filter 709 allocated for common signals, Physical channels and signals. At this time, the common signal can be generated by using the numerical method defined for the common signal. Also, the resource mapping unit 707 can freely set the frequency position where the common signal is transmitted, unlike the existing LTE. The transmitter of the base station includes a multiplexer 710 for multiplexing the respective filter outputs. The transmission unit of the base station includes a resource mapping unit 701, 704 and 707, OFDM modulation units 702, 705 and 708, filters 703, 706 and 709, and a control unit for efficiently controlling the multiplexing unit 710 711). Finally, the transmission unit of the base station includes an RF unit 712 and an antenna for transmitting to the mutually multiplexed service terminals in the multiplexer 710.

Next, the functional block configuration and operation of the receiver of the terminal according to the present invention will be described with reference to FIG.

The terminal receiver includes an antenna and an RF unit 801, filters 802 and 805, OFDM demodulators 803 and 806, resource extractors 804 and 807, and a controller 808. A plurality of filters 802 and 805, OFDM demodulators 803 and 806 and resource extractors 804 and 807 need to support two or more different services having different numbers. In FIG. 8, The example of support is shown. The signal received by the terminal is converted into a baseband signal in the passband through the RF unit 801. [ The baseband converted signal is input to the filters 802 and 805. The terminal can turn on / off the filter according to the service to be received, or change the numerator of the filter. At this time, the filter is used to remove the interference of the FDM signal in the adjacent frequency domain. OFDM demodulators 803 and 806 are used for OFDM demodulation of the filtered signal. The OFDM demodulators 803 and 806 may include a cyclic prefix removal and an FFT. The resource extracting units 804 and 807 extract a physical channel and a signal from the resource occupied by each service. The control unit 808 can control a series of processes so that the terminal can operate according to each of the embodiments of the present invention described above.

Further, each of the above embodiments can be combined with each other as needed. For example, the first embodiment, the second embodiment, and the third embodiment may be combined with each other to operate the base station and the terminal. In this case, the control unit 808 of the terminal and the control unit 711 of the base station can control to operate according to the combination of the embodiments.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory only and are not intended to limit the scope of the invention. Accordingly, the scope of the present invention should be construed as being included in the scope of the present invention, all changes or modifications derived from the technical idea of the present invention.

711:
701, 704, 707: resource mapping unit
702, 705, 708: OFDM modulation section
703, 076, 709: base station filter
710:
712: base station RF section
801: terminal RF section
802, 805: terminal filter
803, 806: OFDM demodulator
804, 807: resource extracting unit
808:

Claims (1)

A signal transmission method for initial connection of a terminal,
Mapping a synchronization information signal, a master information block (MIB), and a system information block (SIB) to a predetermined frequency domain; And
And transmitting the mapped information to the terminal.

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