KR20080016390A - Method for transmitting and receiving signal in the communication system using variable length cyclic prefix, and basestation and user equipment doing the same - Google Patents

Abstract

A method for transmitting and receiving signals in a communication system by using a variable CP(Cyclic Prefix), and a base station and UE(User Equipment) performing the same are provided to transmit and receive signals stably by using obtained CP length information. A sequence inserting unit(601) inserts CR length information of a sub-frame including one or more of an SCH(Synchronous Channel) and a BCH(Broadcast Channel) into a channel signal of the first SCH including a signal used for timing searching among the SCHs. A transmitting unit(602) transmits the channel signal of the first SCH having the length information which has been inserted by the sequence inserting unit(601) through the sub-frame.

Description

Method for Transmitting and Receiving Signal In The Communication System Using Variable Length Cyclic Prefix, And Basestation and User Equipment Doing The Same}

1 illustrates a radio frame structure in a communication system in which a variable CP is used.

2A and 2B illustrate arrangement relations of a main sync channel, an auxiliary sync channel, and a broadcast channel when inserting length information of a cyclic prefix unit into a main sync channel according to a signal transmission / reception method according to an embodiment of the present invention. Figure.

3A to 3C are diagrams for explaining a method of changing a structure of a sequence to be inserted into a main synchronization channel according to a length of a CP in a signal transmission / reception method according to an embodiment of the present invention.

4 is a diagram for explaining a method of transmitting a synchronization channel and / or a broadcast channel through a subframe having a CP having a constant length according to one embodiment of the present invention;

FIG. 5 is a diagram for explaining a method of transmitting inserting both a synchronization channel and a broadcast channel into a subframe having a constant length CP according to one embodiment of the present invention; FIG.

6 is a view for explaining a method of inserting and transmitting a plurality of synchronization channels and broadcast channels in one subframe having a CP of a constant length according to an embodiment of the present invention.

FIG. 7 is a block diagram schematically showing a characteristic configuration of a base station for inserting and transmitting length information of a CP into a primary synchronization channel according to an embodiment of the present invention. FIG.

FIG. 8 is a block diagram schematically illustrating a characteristic configuration of a user equipment that receives length information of a CP when the length information of a CP is inserted into a main synchronization channel according to an embodiment of the present invention; FIG.

FIG. 9 is a block diagram schematically illustrating only a characteristic configuration of a base station for inserting and transmitting these channel signals in a subframe having a predetermined length when transmitting a synchronization channel and / or a broadcast channel according to an embodiment of the present invention. .

FIG. 10 is a schematic diagram illustrating only a characteristic configuration of a user device that receives a synchronization channel and / or a broadcast channel signal through a subframe having a predetermined length and obtains CP length information according to an embodiment of the present invention. Block diagram shown.

The present invention relates to a communication technology, and more particularly, to a method for transmitting and receiving a signal in a communication system using a variable CP, and a base station and user equipment performing the same.

The basic principle of orthogonal frequency division multiplexing (OFDM) is to divide a high-rate data stream into a large number of low-rate data streams, which use multiple carriers. It is transmitting at the same time. Each of the plurality of carriers is called a subcarrier. Since orthogonality exists between the multiple carriers of the OFDM, the frequency components of the carriers can be detected at the receiving end even if they overlap each other. The high data rate data stream is converted into a plurality of low data rate data streams through a serial to parallel converter, and each subcarrier is added to the plurality of data streams converted in parallel. After multiplying, each data string is summed and sent to the receiving end. A plurality of parallel data streams generated by the serial / parallel transform unit may be transmitted to a plurality of subcarriers by an inverse discrete fourier transform (IDFT), and the IDFT is an inverse fast fourier transform (IFFT). Can be implemented efficiently. Since the symbol duration of the low carrier subcarrier is increased, relative signal dispersion in time caused by multipath delay spread is reduced.

Inter-symbol interference can be reduced by inserting a guard interval longer than the delay spread of the channel between OFDM symbols. In addition, if a part of the OFDM signal is copied to the guard interval and placed at the beginning of the symbol, the OFDM symbol may be cyclically extended to protect the symbol. This guard interval is generally called a cyclic prefix (CP).

In a cellular OFDM system, it is necessary to design and use CPs having different lengths according to the environment to which each cell belongs or the data characteristics transmitted within the cell. For example, a cell operating in a radio channel environment having a high delay spread may use a long CP, and a cell operating in a radio channel environment having a low delay spread may use a short CP. As another example, data requiring high reception performance in one cell may be transmitted using a long CP, and data requiring relatively low reception performance may be transmitted using a short CP.

1 is a diagram illustrating a radio frame structure in a communication system in which a variable cyclic prefix is used.

In general, when a downlink transmission unit of a cellular OFDM system is divided into radio frames, subframes, and OFDM symbols on a time axis, a plurality of OFDM symbols constitute one subframe, as shown in FIG. 1, and a plurality of subframes. This one radio frame is configured. At this time, assuming that different CP lengths can be applied to each subframe as described above, as shown in FIG. 1, the number of OFDM symbols in a subframe to which the number of OFDM symbols in a subframe to which a long CP is applied is short. It is less than the number. 1 shows an example in which a subframe using a long CP length on the left includes six OFDM symbols and a subframe using a short CP length on the right includes seven OFDM symbols.

Meanwhile, the purpose of a broadcast channel (BCH) and a synchronization channel (SCH) according to the technical field will be described below.

In a cellular OFDM system, a process of synchronizing a user terminal with a base station is called a cell search process, and this process is performed based on two signals, SCH and BCH. That is, the symbol timing (at least the SCH signal timing) of the received signal and the frequency synchronization are acquired based on the received SCH, and the information of the cell and system information which are basically required for the communication with the corresponding cell in the subsequent process are SCH, Acquisition via BCH.

In general, the period of transmitting SCH and BCH is designed to minimize the length of the radio frame, and according to the required SCH detection performance and the amount of information transmitted in the BCH, a plurality of OFDM symbols in one radio frame Can be used for transmission.

In the cellular wireless mobile communication system, since the basic information on the transmission format of the base station is generally transmitted through the BCH, information on the transmission frame structure including the CP length when the CPs having different lengths can be used in one cellular OFDM system is also available. It is conceivable to transmit on the BCH. However, since the terminal must first detect the SCH at the initial access to any cell, it must be able to stably detect the SCH regardless of which CP length the cell uses. In addition, once the SCH is detected, a CP length applied to a subframe in which each corresponding signal is transmitted in order to know a relative position of a subsequent series of signals (for example, additional SCHs, BCHs, reference symbols, etc.) Need to know.

Therefore, there is a need for a technique for acquiring information about a CP length used when receiving a SCH prior to receiving a BCH, and there is a need for improvement of a base station transmission method and a reception method of a user equipment.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to propose a method for obtaining information on CP length of a subframe to be used in a corresponding communication upon reception of an SCH, and a configuration of a base station and a user equipment therefor.

Another object of the present invention is to propose a technique for stably transmitting and receiving a signal even when using a variable CP length by using the CP length information thus obtained.

A signal transmission method of a base station according to an embodiment of the present invention for achieving the above object is a signal used for timing retrieval of the cyclic prefix length information of a subframe including at least one of a synchronization channel and a broadcast channel; Inserting into a channel signal of a first synchronization channel comprising a; And transmitting the channel signal of the first synchronization channel through the subframe.

In this case, the cyclic prefix length information of the subframe not including both the sync channel and the broadcast channel may be inserted into a channel signal of the broadcast channel and transmitted, wherein the sync channel may include a primary sync channel and an auxiliary sync channel. And the first sync channel including a signal used for the timing search may be the main sync channel.

In addition, the length of the cyclic prefix portion of the sub-frame including one or more of the sync channel and the broadcast channel may have the same length, and the inserting the cyclic prefix length information into the channel signal may include: Any one sequence according to the cyclic channel length of the synchronization channel and the broadcast channel, from among a first sequence indicating a case in which the length has a first length and a second sequence indicating a case in which the length of the cyclic prefix has a second length; Selecting and inserting into the channel signal.

In addition, the length of the cyclic prefix of the sub-frame in which the sync channel is inserted may have a predetermined length.

On the other hand, the signal reception method of the user equipment according to another embodiment of the present invention comprises the steps of receiving a channel signal of the first synchronization channel including a signal used for timing search; And obtaining cyclic prefix length information of a subframe including at least one of a full sync channel including the first sync channel and a broadcast channel from the channel signal of the first sync channel.

In this case, the acquiring the cyclic prefix length information from the channel signal may include: a first sequence indicating a case in which the cyclic prefix portion has a first length, and the cyclic prefix length is a second length; The method may include determining which of the first sequence and the second sequence includes the channel signal by performing a correlation operation with a second sequence indicating a case in which the signal has a value.

A signal transmission method of a base station according to another embodiment of the present invention is a signal transmission method of a base station in a communication network, comprising: setting a subframe having a predetermined cyclic prefix length; And when one or more of a synchronization channel and a broadcast channel are transmitted, inserting the subchannel into the subframe.

In this case, the cyclic prefix part of the subframe used in the communication network includes a cyclic prefix part having a first length and a cyclic prefix part having a second length, wherein the constant cyclic prefix part is the first length and the first length. May be longer than the second length.

In the transmitting step, both the synchronization channel and the broadcast channel may be inserted and transmitted in the subframe, and a plurality of synchronization channels may be inserted and transmitted in the subframe.

In addition, the cyclic prefix length information of the subframe not including both the sync channel and the broadcast channel may be inserted into a channel signal of the broadcast channel and transmitted.

According to another aspect of the present invention, there is provided a method of receiving a signal of a user device in a communication network, the method comprising: receiving a subframe having a predetermined cyclic prefix length; And obtaining cyclic prefix length information of subframes other than the subframe from at least one of a synchronization channel and a broadcast channel inserted into the subframe.

On the other hand, the base station according to another embodiment of the present invention is a first synchronization including a signal used for timing retrieval of the cyclic prefix length information of the sub-frame including one or more of the synchronization channel and the broadcast channel for the synchronization channel A sequence inserter to insert a channel signal of a channel; And a transmitter for transmitting the channel signal of the first synchronization channel in which the length information is inserted by the sequence inserter through the subframe.

In addition, a user device according to another embodiment of the present invention includes a receiver for receiving a channel signal of a first synchronization channel including a signal used for timing search; And an information acquisition unit for obtaining cyclic prefix length information of a subframe including at least one of a total synchronization channel including the first synchronization channel and a broadcast channel from the channel signal of the first synchronization channel.

In addition, the base station according to another embodiment of the present invention includes a sub-frame setting unit for setting a sub-frame having a predetermined cyclic prefix length; And a control unit controlling to insert and transmit the sub-frame set by the sub-frame setting unit when transmitting one or more of a synchronization channel and a broadcast channel. The user device according to another embodiment of the present invention A receiver for receiving a subframe having a predetermined cyclic prefix length; And an information acquisition unit for obtaining cyclic prefix length information of subframes other than the subframe from at least one of a synchronization channel and a broadcast channel inserted into the subframe received by the receiver.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. For example, in the following detailed description, the downlink frame structure is mainly described in the structure discussed in the 3GPP LTE downlink system, but the scope of the present invention is illustrated below as long as it includes the characteristic configuration of the present invention. It does not need to be limited to the frame structure. In addition, in the following detailed description, terms such as “base station” and “terminal” are used as signal transmitting / receiving subjects, but this is used as an example of an arbitrary transmitting / receiving subject in a communication system, and a subject and a receiver for transmitting signals in downlink. It may include any subject that is a subject.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form, centering on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

The present invention proposes a method for obtaining a CP length of a subframe in which a UE transmits SCH and BCH and a related subframe design method in downlink transmission of a cellular OFDM system using two or more CP lengths.

First, a description will be given of a method in which a terminal according to an embodiment of the present invention acquires CP length information during an initial timing search using SCH.

In general, the UE not only acquires the timing initially through the SCH but also obtains additional cell search information. According to the hierarchical SCH structure, which is currently discussed in 3GPP LTE, such a SCH is divided into two P_SCHs (primary SCHs) and S_SCHs (secondary SCHs) according to the function of each SCH. Can be. For example, using the code sequence of the P_SCH as a function of each function, the timing search and frequency correction of the signal transmission sent from a specific cell even when the terminal does not know which cell it belongs to The code sequence of the S-SCH is basically a cell or a neighbor to which the terminal is connected after timing the timing using a different sequence for each cell information (for example, cell ID, CP length, etc.). It can be configured to obtain the information of the cell.

According to an embodiment of the present invention, in addition to the above-described functions of the SCH, a method of including CP length information of a subframe to which at least one of the SCH and the BCH belongs is included in a sequence applied to the SCH. As described above, in case of transmitting CP length information of all subframes using only BCH, it is difficult to stably detect the SCH signal because the CP length of the subframe receiving the SCH used for initial timing search and cell search is not known. For example, the stable detection of a subframe including the BCH itself is also difficult. Therefore, as in the above-described embodiment of the present invention, by including the CP length information of the subframe including one or more of the SCH and the BCH in the P_SCH including the SCH, in particular, the sequence used for the initial timing search, the SCH and the BCH Stable detection is possible, and when the BCH can be stably detected, it is possible to stably transmit CP information of a subsequent subframe through the BCH.

2A and 2B illustrate arrangement relations of a main sync channel, an auxiliary sync channel, and a broadcast channel when inserting length information of a cyclic prefix unit into a main sync channel according to a signal transmission / reception method according to an embodiment of the present invention. Figure is a diagram.

In an embodiment of the present invention, the P_SCH may be transmitted in a subframe different from the subframe in which the S_SCH and / or BCH is transmitted, wherein the P_SCH includes CP length information of the subframe in which the S_SCH and / or BCH is transmitted. can do. In this case, as illustrated in FIG. 2A, P_SCH and S_SCH may be inserted into the last OFDM symbol of each subframe, and the CP length of the subframe including the BCH may be included in the P_SCH. Alternatively, the S_SCH and the BCH may be transmitted through the same subframe, and the CP length information of the S_SCH and the BCH may be further facilitated by including the CP length information of the subframe including both the S_SCH and the BCH in the P_SCH.

Meanwhile, in another embodiment of the present invention, as shown in FIG. 2B, P_SCH, S_SCH, and BCH are all included in the same subframe, and P_SCH includes CP length information of the subframe in which the P_SCH is included. S_SCH and BCH can be stably detected.

In the above-described embodiments, it is preferable to insert the CP length information of the subframe to which the SCH and / or BCH belongs to the P_SCH including a signal for initial timing detection. If all cell information is sent to the S_SCH, this may be a big problem in a system where the number of cell IDs that can be transmitted through the S_SCH is insufficient. For example, when there are two types of CP lengths and S_SCH codes need to transmit 128 pieces of information, sending information about CP lengths through the S_SCH will reduce the number of cell IDs that can be transmitted in half. Can be. This is because the information of the S_SCH must be grouped for each CP type so that 64 pieces of information should be divided. However, in a system in which the number of cell IDs that can be transmitted through the S_SCH is somewhat marginal, it is possible to transmit CP length information of the subframe to which the SCH and the BCH belong to the aforementioned S_SCH. In addition, unlike the above-described hierarchical SCH structure discussed in 3GPP LTE, there is no distinction between P_SCH and S_SCH in a communication system using a non-hierarchical SCH structure. It is possible to transmit the CP length information of the subframe to which it belongs, and also to transmit the CP length information of the subframe to which the BCH belongs.

Meanwhile, according to an embodiment of the present invention, in order to include the CP length information of the subframe including the SCH and / or the BCH in the SCH, particularly the P_SCH, as described above, the specific P_SCH having information corresponding to the type of the CP length is included. You can send the code. That is, by transmitting a P_SCH code including a specific sequence selected according to a CP length of a subframe including SCH and / or BCH among a specific sequence indicating a case where a CP has a long length and a specific sequence indicating a case where a CP has a long length. This can be distinguished. The method of transmitting CP length information of the subframe to which the SCH and / or BCH belongs is described in more detail as follows.

In general, signals inserted into the SCH, i.e., specific sequences, may be different in both the mobile communication system and the system under development. In the case of 3GPP LTE, the CAZAC sequence is based, whereas in the case of WCDMA, it is based on the Gold Code.

Briefly describing the CAZAC sequence mainly discussed in 3GPP LTE, two kinds of the sequence are used, namely GCL CAZAC and Zadoff-Chu CAZAC. The relationship between these two types is tied together by a conjugate complex relationship, so Zadoff-Chu CAZAC is obtained by applying the conjugate complex operation to the GCL CAZAC. Zadoff-Chu CAZAC is given by

Here k denotes a sequence index, N denotes a length of a CAZAC sequence to be generated, and M denotes a sequence ID.

Hereinafter, the CP length information is applied using the CAZAC sequence applied to the SCH to distinguish between a subframe having a long CP length and a subframe having a short CP length, and a repetition structure in a time domain included in the P_SCH. Embodiments for obtaining the description will be described.

3A to 3C are diagrams for describing a method of changing a structure of a sequence to be inserted into a main sync channel according to a length of a CP in a signal transmission / reception method according to an embodiment of the present invention.

In FIG. 3A, a code sequence of P_SCH indicating a long CP length is represented by P_SCH ₁ , and a code sequence of P_SCH indicating a short CP length is represented by P_SCH ₂ , and each of C 1 and C 2 represents a CAZAC sequence ID. It is represented by a sequence of different M values. That is, when the CP length of the subframe including the SCH and / or BCH is long, the base station may transmit P_SCH ₁ as a code sequence to be included in the P_SCH, and insert and transmit P_SCH ₂ when having a short CP length.

In addition, in order to obtain the CP length information of the subframe including the SCH / BCH through the above-described code sequence, the terminal receiving the P_SCH ₁ described above. And P_SCH ₂ , and the P_SCH ₁ described with reference to the channel signal of the received P_SCH. And which code sequence is used through correlation with both P_SCH ₂ , thereby obtaining what length the CP length of the subframe including the SCH / BCH simultaneously with the acquisition of the initial timing information. Able to know. In addition, when CP length information of a subframe including SCH / BCH is obtained as described above, CP length information of another subframe may be obtained through a BCH, and thus, a signal may be more stably received. Can be.

Meanwhile, unlike FIG. 3A, FIG. 3B illustrates a case in which circular shift is used to use different sequences according to CP lengths. That is, when the CP length of a subframe including SCH / BCH is long, P_SCH ₁ which is not cyclic shifted is inserted as a sequence applied to P_SCH. When the CP length is short, cyclic shift is performed to a certain degree compared to P_SCH ₁ . These can be distinguished by using the code sequence P_SCH ₂ . In this case, the receiving side also performs correlation operation with the received channel signal using all of the code sequences, thereby confirming whether the code sequence inserted in the received channel signal is any of the P_SCH ₁ and P_SCH ₂ . Information on CP length of a subframe including BCH may be obtained. Alternatively, a delay value applied to the sequences may be obtained by performing a differential operation of two symbols having a time interval, and thereby CP length of the corresponding subframe. It is also possible to obtain information.

In the above-described embodiment shown in FIGS. 3A and 3B, the case in which the CAZAC sequence is used as the sequence to be inserted into the P_SCH has been described as an example. However, the sequence may be changed by using sequences having different IDs as shown in FIG. 3A. Any sequence other than the above-described CAZAC sequence may be used as long as it can be distinguished from each other, or as long as a sequence can be distinguished from each other by applying a delay as in the case of FIG. 3B.

In addition, the embodiment illustrated in FIG. 3C is a method of distinguishing a sequence indicating a long CP length from a sequence indicating a short CP length using a repeating structure included in the P_SCH, unlike FIGS. 3A and 3B.

A method of acquiring synchronization using the P_SCH is generally performed through a cross correlation operation using a sequence commonly used in the entire network included in the P_SCH. However, in the current 3GPP LTE, a sequence inserted into the P_SCH is performed in the frequency domain. By inserting at regular intervals, a P_SCH structure has been discussed in which a synchronization structure can be obtained through an autocorrelation operation through this repetition structure by having a repetition structure a predetermined number of times in one OFDM symbol in the time domain. Although FIG. 3C illustrates an example in which one OFDM symbol has two repetition structures on a time axis, the number of repetitions may be any number depending on an interval in which a sequence is inserted in the frequency domain.

Also in this embodiment, when a CP of a subframe including one or more of SCH and BCH is a long CP, it is transmitted using P_SCH ₁ shown in FIG. 3C, and when a CP has a short CP length, it is transmitted using P_SCH ₂ . do. In this case, P_SCH ₁ has a form in which the same sequence is inserted to the repetition structure included in 1 OFDM symbol as shown in FIG. 3C, and P_SCH ₂ inserts the same sequence in the repetition structure included in 1 OFDM symbol. We propose a method of distinguishing them by inserting them differently. Through this, the receiving end can obtain CP length information of the subframe to which the SCH / BCH belongs according to whether the codes of the sequences inserted in the repetition structure of one OFDM symbol are the same or different.

3A to 3C as described above are for explaining a specific example of a sequence applied to distinguish between a long CP length and a short CP length, and in addition to the above examples, it does not interfere with acquisition of synchronization using P_SCH. Unless it is possible to modulate by any code to distinguish such CP length information, the scope of the present invention need not be limited to the above-described example.

On the other hand, when the subframes to which the SCH or the BCH belongs use CPs having different lengths, the types of CP length information to be transmitted through the P_SCH may increase. Accordingly, according to an embodiment of the present invention, the subframes to which the SCH or the BCH belongs may all use the same CP length, thereby reducing the amount of CP length types to be transmitted through the P_SCH code. In this way, if the CP length type of the subframe including the SCH or the BCH to be transmitted through the P_SCH indicates only whether the long CP length or the short CP length is present for all the subframes including any one or more of all the SCHs and the BCHs, The amount of information carried by the P_SCH can be reduced. The embodiments as described above with reference to FIGS. 3A and 3C illustrate the case where only two sequences are distinguished as different kinds of sequences. However, the present invention is not limited to the above-described embodiment, and also includes a case in which CP length information of all subframes including any one or more of SCH and BCH is transmitted through P_SCH. In this case, as shown in FIG. 3A, sequences having different CAZAC IDs may be determined and used as needed, and in FIG. 3B, these sequences may be distinguished using sequences shifted by different cyclic shift degrees. In addition, in the case of FIG. 3C, a combination of various codes can be distinguished for the same sequences inserted into a repetition structure in the time domain of 1 OFDM symbol. It might be possible to define a sequence representing a case.

Hereinafter, a method of fixing a CP length of a subframe in which a SCH or a BCH is transmitted in a cellular system according to another embodiment of the present invention will be described.

In this method, a subframe having a constant CP length is set as defined in a communication network, and when one or more of SCH and BCH are transmitted, the subframe having a predetermined constant length is inserted and transmitted as described above. That's the way. According to this embodiment, first, when the CP length is fixed, an additional signal design for transmitting CP length information of a subframe to which a specific SCH (or BCH) belongs is not necessary, and the user terminal keeps in mind the CP length. There is no need to do a search and further simplify the overall physical channel structure and resource allocation in the system. In this case, the fixed constant CP length may be a length predetermined according to a standard or the like, and the constant CP length should be a value known to both the base station and the user equipment.

In addition, the predetermined CP length preferably has the longest CP length among CP lengths of subframes used in a communication network.

4 is a diagram for describing a method of transmitting a synchronization channel and / or a broadcast channel through a subframe having a CP having a constant length according to one embodiment of the present invention.

4 shows a subframe including the SCH (left side) and a subframe including the BCH (right side), respectively, both of which include OFDM symbols having a long CP length. As shown in Fig. 4, by fixing the CP of the subframe including the SCH and / or the BCH to the longest of the available CP length options, the SCH and / or or The information in the BCH can be searched more reliably.

In addition, another embodiment of the present invention proposes to transmit SCH and BCH through OFDM symbols in the same subframe using a long CP.

FIG. 5 is a diagram for describing a method of transmitting a broadcast channel by inserting both a synchronization channel and a broadcast channel into a subframe having a certain length of CP according to an embodiment of the present invention.

FIG. 5 illustrates that one SCH and a BCH are inserted in one OFDM symbol in one subframe of a transmitted radio frame, and the subframe including the same includes an OFDM symbol having a long CP length. In an embodiment of the present invention, when the subframe including the SCH or the BCH has a long CP length, when the SCH and the BCH are transmitted through OFDM symbols of different subframes as shown in FIG. 4, the corresponding subframe All of them have to apply a long CP length, so that downlink frequency-time resource allocation for CP transmission increases, which may reduce overall downlink data transmission efficiency. Accordingly, in the scheme of fixing the CP length of the subframe in which the SCH or the BCH is transmitted to the long CP length as in the above-described embodiment, the downlink data transmission efficiency can be reduced by transmitting the SCH and the BCH in the same subframe as shown in FIG. 5. have. In addition, since the BCH and the SCH coexist in one subframe, the transmission time interval of the SCH and the BCH can be reduced, so that the BCH can be correlated by using the channel response estimated based on the SCH without additional reference symbols (overhead). coherent detection. In addition, since the SCH and the BCH are in one subframe, the process from the initial timing search to the BCH search and cell information acquisition can be performed quickly and stably with respect to channel change.

On the other hand, according to another embodiment of the present invention, when the SCH is transmitted through a plurality of OFDM symbols in one radio frame, one using a large (or all) long CP of the OFDM symbols to be transmitted SCH We propose a method of transmitting in a subframe.

FIG. 6 is a diagram for describing a method of inserting and transmitting a plurality of sync channels and broadcast channels in one subframe having a CP having a constant length according to an embodiment of the present invention.

FIG. 6 illustrates a case where the longest CP is used in an LTE downlink system currently being developed as a next-generation broadband cellular communication system standard in the 3GPP standard, and the number of symbols that can fit in one subframe is 6 For example, a case in which four SCHs are used, one BCH is used, and one symbol not used for SCH or BCH transmission is shown as an example. The SCH (or BCH) can be transmitted through multiple OFDM symbols in one radio frame to achieve the required detection performance even at low SNR. The use increases the overhead. In order to solve such a problem, as in the above-described embodiment, if the OFDM symbols for transmitting a plurality of SCHs exist in one subframe, the aforementioned overhead problem can be solved.

Based on the above description, the configuration of the base station and the user equipment according to the preferred embodiments of the present invention will be described below. The following description will only describe the characteristic configuration of the base station and the user equipment, the description of the configuration of the general base station and the user equipment will be omitted.

7 is a block diagram schematically illustrating a characteristic configuration of a base station for inserting and transmitting length information of a CP into a main synchronization channel according to an embodiment of the present invention.

A base station according to an embodiment of the present invention includes a sequence inserter 601 and a transmitter 602 as shown in FIG. As shown in FIG. 7, the sequence inserting unit 601 may receive a sequence C ₁ representing a long CP length and a sequence C ₂ representing a short CP length. These sequences C ₁ , C ₂ may be formed upon transmission of a subframe including BCH and / or SCH by any sequence forming apparatus in the base station, and have already been generated as previously defined by the corresponding communication system. May be stored by a known storage device. The sequence inserting unit 601 which has received such sequences C ₁ and C ₂ also receives CP length information of a subframe including SCH / BCH and selects a sequence indicating the length information. FIG. 7 exemplarily illustrates a case in which a sequence C ₁ representing a case having a long CP length among the sequences C1 and C2 is selected. The selected sequence is inserted into the P_SCH and transmitted to the transmitter 602, and the transmitter transmits it through a specific subframe.

As shown in FIG. 7, the sequence inserter 601 selects a sequence capable of indicating CP length information of a subframe including SCH / BCH among sequences indicating a long CP length and a short CP length according to a function thereof. The sequence selector 601a and the combiner 601b for coupling the selected sequence to the P_SCH may be divided into other configurations, as long as the above-described functions are performed.

FIG. 8 is a block diagram schematically illustrating a characteristic configuration of a user equipment that receives length information of a CP when the length information of a CP is inserted into a main synchronization channel according to an embodiment of the present invention.

As shown in FIG. 8, the user device according to the exemplary embodiment of the present invention includes a receiver 701 and an information acquisition unit 702. The receiver 701 receives, by the base station, P_SCH including CP length information of a subframe including one or more of SCH and BCH, and transmits the P_SCH to the information acquirer 702. FIG. 8 illustrates an example in which such a P_SCH includes a sequence C ₁ indicating a long CP length. Thereafter, the information acquisition unit 702 performs correlation with the sequence C ₁ representing the long CP length, the sequence C ₂ representing the short CP length, and the received P_SCH signal. The above-described sequences C ₁ and C ₂ may be generated when a user equipment receives a P_SCH signal by a separate sequence forming apparatus, and may be generated by any storage device as previously defined in the corresponding communication system. It may be a stored sequence. However, it should be substantially identical to the sequence used by the base station described with reference to FIG. 7 to indicate CP length information of a subframe including the SCH / BCH. As described above, the information acquisition unit 702 obtains CP length information of a subframe including SCH / BCH through a result of performing a correlation operation on the received P_SCH signal with each of the sequences C ₁ and C ₂ . . In the example shown in FIG. 8, since the sequence C ₁ indicating the long CP length is transmitted to the received P_SCH, the user equipment determines that the subframe including the SCH / BCH includes an OFDM symbol having a long CP length. And these signals can be received.

In addition, as shown in FIG. 8, the information acquisition unit 702 performs correlation between the received signals of the P_SCH and the sequences C ₁ and C ₂ representing the short and long lengths of the CP length according to their function. The unit 702a and the correlation values CV ₁ and CV ₂ may be divided into a determination unit 702b that determines CP length information of a subframe including SCH / BCH, but may perform the above-described function. As shown in FIG. 8, the configuration may be divided and implemented.

FIG. 9 is a block diagram schematically illustrating only a characteristic configuration of a base station for inserting and transmitting these channel signals in a subframe having a predetermined length when transmitting a synchronization channel and / or a broadcast channel according to an embodiment of the present invention. to be.

The base station according to the embodiment of the present invention illustrated in FIG. 9 includes a control unit 801 and a subframe setting unit 802. First, the controller recognizes whether the SCH / BCH is transmitted and instructs the subframe setting unit 802 to form a subframe including only OFDM symbols having a constant CP length when there is transmission of the SCH / BCH. In this case, the CP length used by the subframe set by the subframe setting unit 802 may use a length determined according to a predetermined definition in the corresponding communication system. It is desirable for stable transmission of BCH. The subframe having a constant CP length formed by the subframe setting unit 802 is then used to transmit inserting the SCH / BCH. On the other hand, when transmitting a subframe that does not include both SCH and BCH, the variable CP is not transmitted through a subframe having a fixed CP length set by the subframe setting unit 802 described above, and is variable according to a request of a communication system. It can be transmitted through a subframe having a length, and CP length information of such a subframe can be obtained to the receiver through the above-described BCH.

FIG. 10 is a schematic diagram illustrating only a characteristic configuration of a user device that receives a synchronization channel and / or a broadcast channel signal through a subframe having a predetermined length and obtains CP length information according to an embodiment of the present invention. The block diagram shown.

A user device according to an embodiment of the present invention illustrated in FIG. 10 includes a receiver 901 and an information acquisition unit 902. First, the receiver 901 receives a signal transmitted through a subframe having a constant CP length. This subframe includes one or more of SCH and BCH, and the SCH / BCH information thus obtained is transmitted to the information acquisition unit 902. The information acquisition unit 902 may acquire information necessary for cell search including initial synchronization information from the received SCH, and obtain CP length information to be used in a subframe not including both the above-described SCH and BCH from the BCH. Can be. As a result, the user equipment may recognize the CP length used in a subsequent subframe, thereby stably receiving a signal.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. While the foregoing has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

According to the signal transmission / reception method and the base station and the user equipment which perform the same according to the embodiment of the present invention as described above, CP length information used by a subframe including SCH or BCH is transmitted through P_SCH, thereby initial timing. Since the CP length information of the subframe including the SCH or the BCH can be obtained in the information acquisition step, the signal reception can be more stable than the technique of transmitting the CP length information using only the BCH.

In this case, according to an embodiment in which the CP length of the subframe including the SCH and the CP length of the subframe including the BCH are the same, the CP length information of the subframe including the SCH / BCH transmitted through the P_SCH The P-SCH may be stably received when the CP length of a subframe including the SCH is constantly defined.

On the other hand, according to another method of transmitting and receiving a signal and a base station and a user equipment that performs the same, in the case of a subframe including one or more of SCH and BCH, by using a CP having a certain length, these signals Can be reliably received.

In this case, the CP length information used in the general subframe not including both the SCH and the BCH is transmitted through the BCH, and the stable reception of the BCH can be performed according to the above-described method. Can be received.

Claims (18)

Inserting cyclic prefix length information of a subframe including at least one of a sync channel and a broadcast channel into a channel signal of a first sync channel including a signal used for timing search among the sync channels; And Transmitting the channel signal of the first synchronization channel through the subframe. The method of claim 1, The cyclic prefix length information of the subframe not including both the synchronization channel and the broadcast channel is inserted into a channel signal of the broadcast channel and transmitted. The method according to claim 1 or 2, The sync channel includes a primary sync channel and a secondary sync channel, And the first sync channel comprising a signal used for the timing search is the main sync channel. The method according to claim 1 or 2, The cyclic prefix length of the subframe including one or more of the synchronization channel and the broadcast channel has the same length. The method according to claim 1 or 2, Inserting the cyclic prefix length information into the channel signal, According to the cyclic prefix length of the synchronization channel and the broadcast channel of the first sequence indicating the length of the cyclic prefix portion having a first length, and the second sequence indicating the length of the cyclic prefix portion has a second length. And selecting one of the sequences and inserting the selected sequence into the channel signal. The method according to claim 1 or 2, The cyclic prefix length of the subframe in which the synchronization channel is inserted has a predetermined length defined in a communication system. Receiving a channel signal of a first sync channel comprising a signal used for timing searching; And Receiving cyclic prefix length information of a subframe including at least one of a full sync channel including the first sync channel and a broadcast channel from the channel signal of the first sync channel. Way. The method of claim 7, wherein Obtaining the cyclic prefix length information from the channel signal, The channel signal is correlated with a first sequence indicating a case in which the length of the cyclic prefix part has a first length, and a second sequence indicating a case in which the length of the cyclic prefix part has a second length. And determining which one of the first sequence and the second sequence includes. A signal transmission method of a base station in a communication network, Setting a subframe having a predetermined cyclic prefix length in the communication network; And When transmitting one or more of a synchronization channel and a broadcast channel, inserting and transmitting in the subframe. The method of claim 9, The cyclic prefix of the subframe used in the communication network includes a cyclic prefix having a first length and a cyclic prefix having a second length. The constant cyclic prefix length is the first length, And the first length is longer than the second length. The method according to claim 9 or 10, In the transmitting step, inserting and transmitting both the synchronization channel and the broadcast channel in the subframe. The method of claim 10, And a plurality of synchronization channels are inserted into the subframe and transmitted. The method according to claim 9 or 10, The cyclic prefix length information of the subframe not including both the synchronization channel and the broadcast channel is inserted into a channel signal of the broadcast channel and transmitted. In the signal receiving method of the user equipment in a communication network, Receiving a subframe having a predetermined cyclic prefix length in the communication network; And And obtaining cyclic prefix length information of subframes other than the subframe from at least one of a synchronization channel and a broadcast channel inserted into the subframe. A sequence inserter for inserting cyclic prefix length information of a subframe including at least one of a sync channel and a broadcast channel into a channel signal of a first sync channel including a signal used for timing searching among the sync channels; And And a transmitter configured to transmit a channel signal of the first synchronization channel in which the length information is inserted by the sequence inserter through the subframe. A receiver for receiving a channel signal of a first sync channel including a signal used for timing searching; And And an information acquisition unit for acquiring cyclic prefix length information of a subframe including at least one of a total synchronization channel including the first synchronization channel and a broadcast channel from the channel signal of the first synchronization channel. A subframe setting unit for setting a subframe having a predetermined cyclic prefix length in a communication network; And And a control unit which controls to insert and transmit in the subframe set by the subframe setting unit when transmitting at least one of a synchronization channel and a broadcast channel. A receiver for receiving a subframe having a predetermined cyclic prefix length in a communication network; And And an information acquisition unit for obtaining cyclic prefix length information of subframes other than the subframe from at least one of a synchronization channel and a broadcast channel inserted into the subframe received by the reception unit.

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