KR100926562B1 - Method for transmitting and receiving of broadcast channel information - Google Patents

Abstract

The present invention relates to a transmission method and a reception method of broadcast channel information.

In the present invention, the transmitter sets the update period of the broadcast channel information including the system frame value to two frames, and transmits the same broadcast channel information included in all coding blocks transmitted in one update period. At this time, the transmitter applies and transmits different bit mapping patterns to all coding blocks transmitted in one update period.

BCH, broadcast channel, SFN, system frame value, bit mapping pattern, interference, soft combining

Description

Method for transmitting and receiving broadcast channel information {Method for transmitting and receiving of broadcast channel information}

The present invention relates to a method for transmitting and receiving broadcast channel information in a mobile communication system.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Information and Communication and the Ministry of Information and Telecommunications Research and Development. .

Since a broadcast channel (BCH) signal includes system information, the same information can be transmitted every transmission period. Accordingly, the receiver may use a soft-combining method of coherently combining and demodulating previously received BCH information and currently received BCH information to improve demodulation performance of the BCH information.

On the other hand, when the BCH signal is transmitted, a system frame number (SFN) is also included and transmitted. In this case, since the SFN is changed every time the BCH signal is transmitted, different bits are transmitted. There is a problem that demodulation is impossible.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method and method for transmitting broadcast channel information for improving demodulation efficiency of broadcast channel information including a system frame value in a mobile communication system.

Broadcast channel information transmission method of a transmitter according to a feature of the present invention for achieving the above object,

Transmitting, in a first frame, first broadcast channel information including a first system frame value using a first bit mapping pattern; And transmitting, in a second frame, the first broadcast channel information by using a second bit mapping pattern different from the first bit mapping pattern.

In addition, the broadcast channel information transmission method of the transmitter according to another aspect of the present invention,

Transmitting first broadcast channel information including a first system frame value using a different bit mapping pattern for each frame during a first update period including a plurality of frames; And transmitting second broadcast channel information including a second system frame value by using a different bit mapping pattern every frame during a second update period different from the first update period.

According to the present invention, since all the same system frame values transmitted within the update period of the broadcast channel information are transmitted using different bit mapping patterns, the receiver can know the correct SFN even if only one coding block is received.

In addition, by changing the bit mapping pattern applied to the coding blocks included in the update period every frame, the phase of the interference component in the two adjacent coding blocks is changed, and thus, the broadcast channel included in the two adjacent coding blocks. Coherent combining information has an effect of increasing the broadcast channel information signal to interference ratio.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… group”, etc. described in the specification mean a unit for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software.

In the present specification, a terminal is a mobile station (MS), a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), a user equipment (User Equipment). It may also refer to a user equipment (UE), an access terminal (AT), and the like, and may include all or some functions of a terminal, a mobile terminal, a subscriber station, a portable subscriber station, a user device, an access terminal, and the like.

In the present specification, a base station (BS) includes an access point (AP), a radio access station (RAS), a node B (Node-B), and an eNB (Evolved Node-B) transmitting and receiving base station (Base) It may refer to a Transceiver Station (BTS), a Mobile Multihop Relay (MMR) -BS, or the like, and may include all or a part of functions such as an access point, a radio access station, a Node B, an eNB, a transceiver base station, and an MMR-BS. have.

Hereinafter, a method of transmitting and receiving broadcast channel information in a mobile communication system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Meanwhile, although an embodiment of the present invention describes an orthogonal frequency division multiplexing (OFDM) based mobile communication system as an example, the present invention may be applied to other mobile communication systems.

1 illustrates an example of a structure of a transmitter in a mobile communication system according to an exemplary embodiment of the present invention, and illustrates a base station transmitter.

Meanwhile, in the embodiment of the present invention, the BCH information includes a system frame number (SFN).

Referring to FIG. 1, a transmitter includes a channel coding unit 110, a symbol converter 120, a multiplexer 130, an Inverse Fast Fourier Transform (IFFT) unit 140, and a radio ( Radio Frequency (RF) transmitter 150 and a transmit antenna.

The channel coding unit 110 includes an encoder 111, a bit mapping unit 112, an interleaver 113, and a scrambler 114.

)를 출력한다. 여기서, N _b 는 인코더(111)가 한번에 출력하는 출력 비트 수를 의미한다. 한편, 인코더(111)는 입력되는 BCH 정보의 비트 수 및 할당 받은 자원의 비에 기초해 반복(repetition) 혹은 펑쳐링(puncturing)을 수행하는 레이트 매칭(rate matching) 블록을 더 포함한다. When the encoder 111 receives the BCH information bit by bit, the encoder 111 encodes the BCH information in a vector format.

) Here, N _b means the number of output bits that the encoder 111 outputs at one time. Meanwhile, the encoder 111 further includes a rate matching block that performs repetition or puncturing based on the number of bits of the input BCH information and the ratio of allocated resources.

)를 출력한다. 여기서, 비트 매핑부(112)의 출력은 다음의 수학식 1과 같이 나타낼 수 있다. The bit mapping unit 112 receives the BCH information encoded by the encoder 111 and performs bit mapping according to a predetermined bit mapping pattern.

) Here, the output of the bit mapping unit 112 may be expressed as in Equation 1 below.

Here, f _n ^(k) represents a bit mapping function corresponding to the bit mapping pattern applied to the n th coding block in the k th cell, and the bit mapping function is an arbitrary function having one-to-one corresponding characteristics. Here, one coding block includes BCH information and other channel information transmitted in one transmission time interval (TTI). In an embodiment of the present invention, one coding block is transmitted including all BCH information.

Equation 2 below shows an example of such a bit mapping function, and represents a bit mapping function as a cyclic shift function when a unique bit mapping function is used for each cell.

Here,% denotes a modular operation and M (k, n) denotes a cyclic shift value used for the nth coding block in the kth cell. Meanwhile, in the embodiment of the present invention, different bit mapping functions are applied to all coding blocks included in the update period of the BCH information.

Meanwhile, although Equation 2 described above shows an example of a bit mapping function in the case where a unique bit mapping function is used for each cell, the present invention may also use the same bit mapping function.

Equation 3 below shows an example of a bit mapping function when all cells use the same bit mapping function, and represents a bit mapping function as a cyclic shift function.

Meanwhile, even in this case, different bit mapping functions are applied to all coding blocks included in the update period of the BCH information.

The BCH information bit-mapped by the bit mapping unit 112 is rearranged according to a pattern determined by the interleaver 113. At this time, the interleaving pattern used for relocation is common to all cells. On the other hand, if bit mapping is performed using different bit mapping patterns for each cell, the output pattern of the interleaver 113 is different for each cell even though all cells use a common interleaving pattern.

The BCH information relocated by the interleaver 113 is output by multiplying the unique scrambling code of each cell by the scrambler 114.

The symbol converter 120 converts BCH information output from the channel coding unit 110 into symbol units through a QPSK-like scheme, and maps each BCH symbol to a time and frequency resource according to a predetermined pattern. do. Here, every transmitted BCH information is composed of a plurality of BCH symbols, and the BCH symbol means a minimum BCH data unit that divides BCH information for use in time and frequency mapping.

The multiplexer 130 arranges other channel symbols and BCH symbols according to a predetermined pattern in the time / frequency domain to finally generate a coding block, and the generated coding block is used to generate the IFFT unit 140 and the RF transmitter 150. Is transmitted through the transmit antenna.

Meanwhile, in the embodiment of the present invention, the position of the bit mapping unit 112 is positioned between the encoder 111 and the interleaver 113, but the present invention may change the position of the bit mapping unit 112. . For example, in the present invention, when the bit mapping unit 112 is positioned after the interleaver 113 as shown in FIG. 2, or when the bit mapping unit 112 is positioned before the encoder 111 as shown in FIG. 3. The same effect can be obtained from.

4 is a flowchart illustrating a method of transmitting BCH information by a transmitter according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating an example of transmitting BCH information by a transmitter according to an embodiment of the present invention.

Referring to FIG. 4, when BCH information in bit units is input, the encoder 111 encodes and outputs it (S101). When the BCH information is encoded and output, the bit mapping unit 112 first selects a bit mapping pattern to be used for transmitting the BCH information (S102).

5 illustrates an example of a method in which the bit mapping unit 112 selects a bit mapping pattern for every transmission of BCH information. 5, the update period of the BCH information is two frames. In addition, a transmission time interval (TTI) of a coding block is one frame, and one coding block includes all BCH information. Therefore, the receiver can know all the BCH information even by performing demodulation on one coding block.

In addition, in FIG. 5, all coding blocks transmitted within an update period are transmitted using different bit mapping patterns (Bit mapping # 0 and Bit mapping # 1). Therefore, the SFN included in each coding block is also transmitted using different bit mapping patterns. In this case, SFNs included in each coding block included in one update period are the same. That is, the SFN is updated according to the update period, not every frame. In addition, the SFN transmitted in each update period corresponds to the number of the frame located first in the update period. This is to synchronize the SFN corresponding to the frame number with the number of transmissions of the frame. Therefore, in the i th frame (Frame # (i)) and the (i + 1) th frame (Frame # (i + 1)), SFN is i and the (i + 2) th frame (Frame # (i + 2) ) And the (i + 3) th frame (Frame # (i + 3)), the SFN becomes i + 2.

Referring back to FIG. 4, when the mapping pattern to be applied to the bit mapping is selected as described above, the bit mapping unit 112 performs bit mapping on the BCH information using the selected bit mapping pattern (S103).

Thereafter, the interleaver 113 interleaves and outputs BCH information bit-mapped by the bit mapping unit 112 according to a predetermined pattern (S104), and the scrambler 114 adds a unique scrambling code of each cell to the interleaved BCH information. The multiplication is performed (S105).

In addition, the symbol converter 120 converts the BCH information scrambled by the scrambler 114 in symbol units and maps each BCH symbol to a time and frequency resource according to a predetermined pattern and outputs the SCH symbol (S106).

Subsequently, the multiplexer 130 arranges the symbol-converted BCH information along with other channel symbols according to a predetermined pattern in a time / frequency domain to finally generate a coding block (S107), and the IFFT unit 140 processes the IFFT transform. (S108) and output. The coding block output after the IFFT conversion is finally transmitted through the RF transmitter 150 and the transmit antenna.

Meanwhile, in the embodiment of the present invention, the step S103 of selecting a bit mapping pattern and performing bit mapping using the step S103 is performed after the step S101 of encoding, but the present invention is performed in steps S102 and S103. It is also possible to change the order of execution of the steps. For example, when the transmitter structure is as shown in FIG. 2, steps S102 and S103 are performed after step S104, and when the transmitter structure is as shown in FIG. 3, steps S102 and S103 are performed before step S101.

As described above, the method of transmitting BCH information has the following effects.

First, the receiver can demodulate the correct SFN even if only one coding block is received.

Conventionally, when updating an SFN every two frames, the receiver does not know whether the received SFN is an SFN value corresponding to the first frame or an SFN value corresponding to the second frame in the update period, so that the receiver cannot demodulate only one coding block. In this case, the exact SFN is not known.

On the other hand, in the embodiment of the present invention, since the same SFN is transmitted using different bit mapping patterns, the receiver can know the correct SFN even if only one coding block is received. That is, after applying all bit mapping patterns used for transmission to one received coding block, demodulation is performed, and the correct SFN value can be known by using the number of the bit mapping pattern without demodulation error and the demodulated SFN value. have.

For example, when the receiver receives the (i + 1) th frame (Frame # (i + 1)) of FIG. 4, the receiver performs demodulation by applying both bit mapping pattern # 0 and bit mapping pattern # 1. do. Thereafter, the receiver confirms that a demodulation error has not occurred with respect to bit mapping pattern # 1, confirms that the corresponding coding block is the second transmitted coding block within an update period, and adds 1 to the demodulated SFN value. Recognize that the SFN for the frame.

 Second, there is an effect that the interference component of the BCH information received by the receiver is randomized.

Since the BCH symbol is transmitted using different frequencies from other channel symbols, when the receiver demodulates the BCH information, the largest interference component is the BCH information transmitted from another cell. Therefore, when the same bit mapping pattern is applied to all coding blocks within the update period of the BCH information, the interference components included in the coding block are the same, and thus, even if the receiver performs coherent combining the two coding blocks. The signal to interference ratio does not increase.

On the other hand, if the bit mapping pattern applied to the coding block included in the update period is changed every frame as in the embodiment of the present invention, the phase of the interference component in two adjacent coding blocks is changed, and thus, the adjacent Coherent combining broadcast channel information included in two coding blocks may increase the broadcast channel information signal to interference ratio.

Meanwhile, in the embodiment of the present invention, the case in which the update period of the BCH information is two frames has been described as an example. However, the present invention may use two or more frames as the update period. Meanwhile, the number of bit mapping patterns to be applied at the time of transmission is determined according to the number of frames included in one update period.

6 illustrates a receiver in a mobile communication system according to an exemplary embodiment of the present invention, and illustrates a receiver located in a terminal.

Referring to FIG. 6, a receiver includes a reception antenna, an RF receiver 210, a fast Fourier transform (FFT) 220, a BCH signal extractor 230, a bit converter 240, and a channel decoder ( 250).

When the signal received through the receiving antenna is input via the RF receiver 210, the FFT unit 220 converts the signal output from the RF receiver 210 into the frequency domain. The BCH signal extractor 230 extracts a BCH symbol from the frequency-converted signal, and the bit converter 240 converts the BCH symbol into BCH information in bits.

The channel decoder 250 includes a descrambler 251, a deinterleaver 252, and a blind decoder 253.

The channel decoder 250 descrambles the output bit of the bit converter 240 through the descrambler 251, deinterleaves the deinterleaver 252, and then decodes the decoder 253 through the blind descrambler 251. Demodulate through).

When one coding block is received, the blinder decoder 253 demodulates each of all bit mapping patterns used for transmission. That is, when the same BCH information is transmitted using two bit mapping patterns as shown in FIG. 5, the blind decoder 253 demodulates each of the two bit mapping patterns. In addition, the demodulation error among the demodulated results for each of the two bit mapping patterns is checked, for example, a demodulation result in which no cyclical redundancy check (CRC) error occurs, and the number and demodulation of the corresponding bit mapping pattern are checked. SFN is obtained using the SFN included in the result.

Here, the number of the bit mapping pattern is determined according to the order of applying the bit mapping pattern in one update period when the BCH information is transmitted, and the transmitter and the receiver share the number of the bit mapping pattern and the bit mapping pattern with each other.

On the other hand, when a demodulation error occurs for all the bit mapping patterns in the first demodulation attempt, the blind decoder 253 performs coherent combining of the next coding block with the previously received coding block and performs demodulation.

In this case, when the coding block received in the current frame is demodulated using the first bit mapping pattern, the result of the demodulation using the second bit mapping pattern is added to the previous coding block, and the coding block received in the current frame is removed. In the case of demodulation using the 2 bit mapping pattern, the result of the demodulation using the first bit mapping pattern is added to the previous coding block. The different selection of the bit mapping pattern applied to the demodulation result added every frame is for synchronizing with the transmitter.

Meanwhile, in the embodiment of the present invention, when the transmitter does not inform the timing corresponding to the update period of the BCH information, the receiver has been described as performing the blinder decoding as an example, but in the present invention, the transmitter corresponds to the update period of the BCH information. If the receiver informs the receiver of the timing of the bit mapping pattern, the receiver knows the application rule of the bit mapping pattern, and thus it is also possible to apply the bit mapping rule according to a rule determined based on the timing informed by the transmitter without performing blind decoding. .

7 is a flowchart illustrating a method of receiving BCH information of a receiver according to an embodiment of the present invention.

Referring to FIG. 7, first, when a signal received through a reception antenna is input through an RF receiver 210, the FFT unit 220 performs an FFT on a signal output from the RF receiver 210 and converts the signal into a frequency domain. In operation S201, the BCH signal extractor 230 extracts the BCH symbol from the signal converted into the frequency domain (S202).

Thereafter, the bit converter 240 converts the extracted BCH symbol into BCH information in units of bits (S203), and the descrambler 251 descrambles and outputs the BCH information converted in units of bits. In addition, the deinterleaver 252 performs deinterleaving on BCH information that is descrambled and output.

The deinterleaved BCH information is input to the blinder decoder 253, and the blinder decoder 253 performs demodulation on each bit mapping pattern used for transmission (S206).

Thereafter, the blind decoder 253 checks the bit mapping pattern in which no error occurs in the corresponding demodulation result among the bit mapping patterns, and checks the number of the bit mapping pattern and the SFN included in the demodulation result corresponding to the bit mapping pattern. SFN is obtained by using (S207).

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a structural diagram illustrating an example of a transmitter in a mobile communication system according to an embodiment of the present invention.

2 is a structural diagram illustrating another example of a transmitter in a mobile communication system according to an exemplary embodiment of the present invention.

3 is a structural diagram showing another example of a transmitter in a mobile communication system according to an embodiment of the present invention.

4 is a flowchart illustrating a method of transmitting broadcast channel information by a transmitter according to an embodiment of the present invention.

5 illustrates an example of broadcasting channel information transmission of a transmitter according to an embodiment of the present invention.

6 is a structural diagram illustrating a receiver in a mobile communication system according to an embodiment of the present invention.

7 is a flowchart illustrating a method of receiving broadcast channel information by a receiver according to an embodiment of the present invention.

Claims (7)

In the broadcast channel information transmission method of the transmitter, Transmitting, in a first frame, first broadcast channel information including a first system frame value using a first bit mapping pattern; And In the second frame, transmitting the first broadcast channel information by using a second bit mapping pattern different from the first bit mapping pattern. Broadcast channel information transmission method comprising a. The method of claim 1, A plurality of frames are included in an update period of the broadcast channel information, and the first frame and the second frame are included in one update period. The method of claim 2, And the first system frame value is the number of the first frame located within the corresponding update period. The method of claim 1, The first bit mapping pattern and the second bit mapping pattern are used in common in all cells. The method of claim 1, And the first bit mapping pattern and the second bit mapping pattern are different from each other in all cells. In the broadcast channel information transmission method of the transmitter, Transmitting first broadcast channel information including a first system frame value using a different bit mapping pattern for each frame during a first update period including a plurality of frames; And Transmitting second broadcast channel information including a second system frame value using a different bit mapping pattern every frame during a second update period different from the first update period. Broadcast channel information transmission method comprising a. The method of claim 6, The broadcast channel information transmission method of claim 1, wherein the order of bit mapping patterns applied every frame during the first update period and the second update period is the same.

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