KR20080039780A - Apparearus and method for synchronization channel and broadcast channel transmission in wireless communication system - Google Patents

Abstract

A method and an apparatus for transmitting SCH(Synchronous CHannel) signals and BCH(Broadcast CHannel) signals in a mobile communication system are provided to improve the performance of channel estimation and to increase the efficiency of broadcast channel demodulation by transmitting a plurality of SCH preambles and a plurality of BCH signals through respectively different beams. An SCH preamble and BCH multiplexer multiplexes two SCH preambles and two BCH signals(S310). A precoding vector multiplexer selects precoding vectors to be used for precoding(S320). A precoder executes precoding by multiplying the preambles and the BCH signals by the selected precoding vectors(S330). An IFFT(Inverse Fast Fourier Transformer) converts the precoded SCH preambles in time-domain Tx signals through inverse fast fourier transformation(S340). An RF(Radio Frequency) transmitter converts the analog Tx signals into RF signals and transmits them through an antenna(S350).

Description

Method and apparatus for transmitting synchronization channel and broadcasting channel in mobile communication system {APPAREARUS AND METHOD FOR SYNCHRONIZATION CHANNEL AND BROADCAST CHANNEL TRANSMISSION IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a method and apparatus for transmitting a synchronization channel and a broadcast channel, and more particularly, to a method and apparatus for transmitting a synchronization channel and a broadcast channel in an OFDM cellular system.

In an OFDM cellular system, when a synchronization channel and a broadcast channel are transmitted adjacent to each other in time, the terminal may estimate the channel using the synchronization channel and use the channel estimation result when demodulating the broadcast channel.

Prior art that obtains diversity gain in a synchronization channel is called Frequency Switching Transmit Diversity (FSTD). FSTD is a method of transmitting two preambles from different antennas. At this time, the transmission frequencies for the two preambles are different.

However, since the FSTD needs to use four preambles when the number of transmitting antennas increases to four, there is a problem in that the complexity increases when the terminal searches for cells in the cell search or demodulates the broadcast channels for demodulation of the broadcast channel. .

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a synchronization channel and a broadcast channel transmission method and apparatus for enabling a terminal of a mobile communication system to efficiently demodulate a broadcast channel.

According to one aspect of the present invention, there is provided a synchronization channel and a broadcast channel transmission method of a mobile communication system, by multiplexing a plurality of different synchronization channel preambles and a plurality of different broadcast channels, and the plurality of synchronization channel preambles. And select a plurality of precoding vectors to be used when precoding the plurality of broadcast channels, wherein the plurality of sync channel preambles and the plurality of sync channel preambles among the plurality of broadcast channels and the plurality of precoding vectors, and Precoding is performed by multiplying a precoding vector corresponding to each of the plurality of broadcast channels.

In accordance with another aspect of the present invention, a synchronization channel and broadcast channel transmission apparatus of a mobile communication system includes a synchronization channel preamble and a broadcast channel multiplexer for multiplexing a plurality of different synchronization channel preambles and a plurality of different broadcast channels. And a precoding vector multiplexer for selecting the plurality of sync channel preambles and a plurality of precoding vectors to be used when precoding the plurality of broadcast channels, the plurality of sync channel preambles, the plurality of broadcast channels, and the plurality of broadcast channels. And a precoder for performing precoding by multiplying the plurality of sync channel preambles and the precoding vectors corresponding to each of the plurality of broadcast channels.

According to the present invention, by transmitting a plurality of sync channel preambles and a plurality of broadcast channels in different beams, the channel estimation performance is improved to increase the efficiency of broadcast channel demodulation.

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, except to exclude other components unless otherwise stated. In addition, the terms “… unit”, “… group” described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software.

Now, a synchronization channel and a broadcast channel transmission method and apparatus in a mobile communication system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a synchronization channel and a broadcast channel transmission apparatus of a base station according to an embodiment of the present invention when there are two antennas, and FIG. It is a block diagram of a channel transmission apparatus. The synchronization channel and the broadcast channel transmission method according to an embodiment of the present invention can be applied to the case of two antennas and the case of four, the difference is that the precoding vector has a dimension of two antennas 2 And 4 antennas, the dimension of the precoding vector is 2 or 4.

1 and 2, a synchronization channel and broadcast channel transmission apparatus according to an embodiment of the present invention is a controller 110, a synchronization channel preamble and a broadcast channel multiplexer 120, precoding vector multiplexing Firearm 130, Precoder 140, Buffer 150, Inverse Fast Fourier Transformer (IFFT) 160, Radio Frequency (RF) Transmitter 170 and Antenna 180 It includes.

The controller 110 is a precoding vector multiplexer for selecting a synchronization channel preamble and a broadcast channel multiplexer control signal and a precoding vector to be used for precoding. Generate a control signal. The sync channel preamble and broadcast channel multiplexer 120 multiplexes two sync channel preambles and two broadcast channels according to frequency (subcarrier) and time. The precoding vector multiplexer 130 selects a precoding vector to use when precoding a sync channel and a broadcast channel at a corresponding frequency.

)의 차원은 2이다. 그리고, 도 2에 도시된 바와 같이 안테나가 4개인 경우에는 프리코딩 벡터(

)의 차원은 2 또는 4이다.As shown in Fig. 1, in the case of two antennas, the precoding vector (

) Has a dimension of 2. As shown in FIG. 2, when four antennas are present, a precoding vector (

) Dimension is 2 or 4.

이다. If each of the two sync channel preambles and the two broadcast channels is transmitted using all four antennas, the dimension of the precoding vector is four. In other words,

to be.

이다. And, if two different preambles of each of the sync channel and the broadcast channel are transmitted using two different antennas, for example, one sync channel preamble is transmitted through antenna 0 and antenna 1 and the other sync When the channel preamble is transmitted through antenna 0 and antenna 1, the dimension of the precoding vector is 2. In other words,

to be.

The precoder 140 performs precoding by multiplying the sync channel preamble and the broadcast channel by a precoding vector.

The buffer 150 stores the precoded sync channel preamble and the precoded broadcast channel and transmits the precoded broadcast channel to the IFFT.

IFFT 160 converts the precoded sync channel preamble and the precoded broadcast channel into a transmission signal in the time domain through inverse fast Fourier transform. The RF transmitter 170 converts the transmission signal in the time domain into a radio frequency and transmits the same through the antenna 180.

Hereinafter, a synchronization channel transmission method in a mobile communication system according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 to 5. 3 is a flowchart illustrating a synchronization channel and a broadcast channel transmission method of a mobile communication system according to an embodiment of the present invention.

The sync channel preamble and the broadcast channel multiplexer 120 multiplex two sync channel preambles and two broadcast channels (S310).

4 is a view showing the structure of a frame according to an embodiment of the present invention. Although FIG. 4 illustrates a case of transmitting a synchronization channel and a broadcast channel twice per frame, the present invention can be applied regardless of the number of times of transmitting the synchronization channel and the broadcast channel per frame.

The number of sync channels may be one as shown in FIG. 4, or may be two temporally adjacent sync channels (main sync channel, sub sync channel). In two cases, channel estimation information for demodulation of a broadcast channel may be obtained using a primary SCH, but a secondary SCH is generally used.

The synchronization channel and the broadcast channel may be frequency division multiplexed (FDM) or time division multiplexed (EDM). In the embodiment of the present invention, time division multiplexing will be described as an example.

As shown in FIG. 4, one frame is composed of several OFDM symbols, and a synchronization channel (SCH) and a broadcast channel (BCH) are located in different OFDM symbols. Two sync channel preambles (SCH # 0, SCH # 1) are located at different frequencies in one OFDM symbol, and two broadcast channels (BCH # 0, BCH # 1) are also located at different frequencies in one OFDM symbol.

That is, the 0 th sync channel preamble (SCH # 0) is located at two subcarrier intervals, and the 1 st sync channel preamble (SCH # 1) is located at a subcarrier where the 0 th main sync channel preamble is not located. The 0 th broadcast channel (BCH # 0) is located at two subcarrier intervals, and the 1 st broadcast channel (BCH # 1) is located at a subcarrier where the 0 th broadcast channel is not located.

The precoding vector multiplexer 130 selects a precoding vector to be used for precoding (S320). A method of selecting a precoding vector according to an embodiment of the present invention will be described with reference to FIGS. 5 to 7.

5 is a diagram illustrating a precoding vector selection method using the same precoding vector and a synchronization channel preamble of the same frequency, and FIG. 6 illustrates a precoding vector using a different synchronization channel preamble and a broadcast channel of the same frequency. FIG. 7 is a diagram illustrating a precoding vector selection method, and FIG. 7 is a diagram illustrating a precoding vector selection method used when the precoding vector is changed for each frame.

은 n 번째 동기 채널 시간에 i(i=0,1) 번째 동기 채널 프리앰블을 프리코딩할 때 사용하는 프리코딩 벡터를 의미한다. 즉,

는 0번째 동기 채널 전송 시간에 0번째 주 동기 채널 프리앰블을 프리코딩할 때 사용하는 프리코딩 벡터이고,

는 0번째 주 동기 채널 전송 시간에 1번째 주 동기 채널 프리앰블을 프리코딩할 때 사용하는 프리코딩 벡터이다. 0번째 주 동기 채널 프리앰 블을 프리코딩할 때 사용하는 프리코딩 벡터와 1번째 주 동기 채널 프리앰블을 프리코딩할 때 사용하는 프리코딩 벡터는 각각 N 개씩 있다. In Figure 5,

Denotes a precoding vector used when precoding the i (i = 0,1) th sync channel preamble at an nth sync channel time. In other words,

Is a precoding vector used to precode the 0 th main sync channel preamble at the 0 th sync channel transmission time,

Is a precoding vector used when precoding the first main sync channel preamble at the 0 th main sync channel transmission time. There are N precoding vectors used for precoding the 0 th main sync channel preamble and N precoding vectors used for precoding the 1 st main sync channel preamble.

과

은 서로 다른 프리코딩 벡터이다. As shown in FIG. 5, two sync channel preambles transmitted through the same OFDM symbol are precoded using different precoding vectors, and the same sync channel preamble transmitted through the same OFDM symbol indicates the same precoding vector. Select a precoding vector to precode. In other words,

and

Are different precoding vectors.

The two broadcast channels transmitted through the same OFDM symbol are also precoded using different precoding vectors, and the precoding vector is selected to precode the same broadcast channel using the same precoding vector.

In this case, the precoding vector used for precoding the broadcast channel may select a precoding vector such as the precoding vector used for precoding a sync channel preamble allocated to the same frequency as the broadcast channel, as shown in FIG. 5. In addition, as shown in FIG. 6, a precoding vector different from a precoding vector used when precoding a sync channel preamble allocated to a frequency such as a broadcast channel may be selected. This may be determined differently according to time resources and frequency resources available for the synchronization channel and the broadcast channel.

As shown in FIG. 5 and FIG. 6, for each of the two synchronization channel preambles and the two broadcast channels, N precoding vectors may be selected for each synchronization channel transmission time, and may be selected as a precoding vector to be used for precoding. As shown in FIG. 7, for each of the two synchronization channel preambles and the two broadcasting channels, N precoding vectors may be changed every frame, and may be selected as a vector to be used for precoding. That is, different precoding vectors may be used for transmitting two sync channels and broadcast channels in one frame, or the same precoding vector may be used.

If the same precoding vector is used to transmit the sync channel and the broadcast channel twice in one frame, diversity gain cannot be obtained within one frame. However, in a frame in which the precoding vector used for the sync channel preamble and the broadcast channel precoding matches the channel vector of the terminal, the signal-to-noise ratio of the sync channel preamble and the broadcast channel in the terminal increases by the beamforming gain.

)와 1번째 동기 채널 프리앰블을 프리코딩할 때 사용하는 프리코딩 벡터(

)는 서로 직교하거나 상관성이 작은 것을 사용하고, 하나의 방송 채널 전송 시간에 0번째 방송 채널을 프리코딩할 때 사용하는 프리코딩 벡터와 1번째 방송 채널을 프리코딩할 때 사용하는 프리코딩 벡터는 서로 직교하거나 상관성이 작은 것을 사용한다.In order to increase the diversity gain, a precoding vector used to precode the 0th sync channel preamble at one sync channel transmission time (

) And the precoding vector used to precode the first sync channel preamble (

) Uses orthogonal or small correlations, and the precoding vector used when precoding the 0th broadcast channel and the precoding vector used when precoding the 1st broadcast channel are different from each other. Use orthogonal or less correlated ones.

과

는 서로 직교하거나 상관성이 작은 것을 사용하고,

과

도 서로 직교하거나 상관성이 작은 것을 사용하는 것이 다이버시티 이득을 증가시킬 수 있다. When the precoding vectors are used in every sync channel transmission time, the precoding vectors used in the adjacent sync channel transmission times are orthogonal or less correlated with each other, and the precoding vectors are changed every frame. In this case, it is possible to increase diversity gain by using orthogonal or small correlations between precoding vectors used in adjacent frames. In other words,

and

Uses things that are orthogonal or have little correlation

and

Also, using orthogonal or small correlations with each other can increase diversity gain.

The precoder 140 performs precoding by multiplying the sync channel preamble and the broadcast channel by the precoding vector (S330). IFFT 160 converts the precoded sync channel preamble into a transmission signal in the time domain through inverse fast Fourier transform (S340). The RF transmitter 170 converts the analog transmission signal into a radio frequency and transmits it through the antenna 180 (S350).

In the embodiment of the present invention, a case of transmitting two sync channel preambles and two broadcast channels has been described. However, the present invention can be applied to both cases of transmitting a plurality of main sync channel preambles.

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 block diagram of a synchronization channel and a broadcast channel transmission apparatus of a base station according to an embodiment of the present invention when there are two antennas.

2 is a block diagram of a synchronization channel and a broadcast channel transmitting apparatus of a base station according to an embodiment of the present invention when four antennas are present.

3 is a flowchart illustrating a synchronization channel and a broadcast channel transmission method of a mobile communication system according to an embodiment of the present invention.

4 is a view showing the structure of a frame according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a precoding vector selection method using a precoding vector having a synchronization channel preamble and a broadcast channel of the same frequency.

FIG. 6 is a diagram illustrating a precoding vector selection method using precoding vectors having different sync channel preambles and broadcast channels having the same frequency.

FIG. 7 is a diagram illustrating a precoding vector selection method used when the precoding vector is changed for each frame.

Claims (18)

In the synchronization channel and broadcast channel transmission method of the mobile communication system, Multiplexing a plurality of different synchronization channel preambles and a plurality of different broadcast channels; Selecting a plurality of precoding vectors to use when precoding the plurality of sync channel preambles and the plurality of broadcast channels; And And a precoding step of multiplying each of the plurality of sync channel preambles and the plurality of broadcast channels with the plurality of sync channel preambles and a precoding vector corresponding to each of the plurality of broadcast channels. And a broadcast channel transmission method. The method of claim 1, Selecting the precoding vector, Selecting a first plurality of precoding vectors to assign to the plurality of sync channel preambles such that the plurality of sync channel preambles use different precoding vectors, respectively; And Selecting a second plurality of precoding vectors to be assigned to the plurality of broadcast channels such that the plurality of broadcast channels use different precoding vectors, respectively. The method of claim 2, And the first plurality of precoding vectors are orthogonal to each other, and the second plurality of precoding vectors are orthogonal to each other. The method of claim 2, The first plurality of precoding vectors are different from the precoding vectors used when precoding the same sync channel preamble among the third plurality of precoding vectors for the sync channel preamble used in the previous sync channel transmission time. The second plurality of precoding vectors are different from the precoding vectors used when precoding the same broadcast channel among the fourth plurality of precoding vectors for the broadcast channel used in the previous broadcast channel transmission time, respectively. . The method of claim 4, wherein The first plurality of precoding vectors are orthogonal to the precoding vectors used when precoding the same sync channel preamble among the third plurality of precoding vectors. And the second plurality of precoding vectors are orthogonal to the precoding vectors used when precoding the same broadcast channel among the fourth plurality of precoding vectors. The method of claim 2, The first plurality of precoding vectors are different from the precoding vectors used when precoding the same sync channel preamble among the fifth plurality of precoding vectors for the sync channel preamble used in the previous frame, And the second plurality of precoding vectors are different from the precoding vectors used when precoding the same broadcast channel among the sixth plurality of precoding vectors for the broadcast channel used in the previous frame. The method of claim 6, The first plurality of precoding vectors are orthogonal to the precoding vectors used when precoding the same sync channel preamble among the fifth plurality of precoding vectors. And the second plurality of precoding vectors are orthogonal to the precoding vectors used when precoding the same broadcast channel among the sixth plurality of precoding vectors. The method of claim 2, And the second plurality of precoding vectors are the same as the precoding vector allocated to the sync channel preamble allocated to the same frequency among the first precoding vectors. The method according to any one of claims 1 to 8, The multiplexing step, And a plurality of primary synchronization channels and the secondary synchronization channel by time division multiplexing (TDM). The method according to any one of claims 1 to 7, Converting a precoded plurality of synchronous channel preambles and the plurality of precoded broadcast channels to inverse Fourier transform into a time domain transmission signal; And And transmitting the transmission signal in the time domain. The method of claim 10, The transmitting step And transmitting the plurality of synchronization channel preambles converted into the transmission signals in the time domain through different antennas, respectively. In the synchronization channel and broadcast channel transmission apparatus of the mobile communication system, A sync channel preamble and a broadcast channel multiplexer for multiplexing a plurality of different sync channel preambles and a plurality of different broadcast channels; A precoding vector multiplexer for selecting the plurality of synchronization channel preambles and a plurality of precoding vectors for use in precoding the plurality of broadcast channels; And A precoder for performing precoding by multiplying each of the plurality of synchronization channel preambles and the plurality of broadcast channels with each of the plurality of precoding vectors and a precoding vector corresponding to each of the plurality of broadcast channels. Sync channel and broadcast channel transmission apparatus comprising a. The method of claim 12, The precoding vector multiplexer Select a first plurality of precoding vectors to be allocated to the plurality of sync channel preambles such that the plurality of sync channel preambles use different precoding vectors, respectively, And a second plurality of precoding vectors to be allocated to the plurality of broadcast channels such that the plurality of broadcast channels use different precoding vectors. The method of claim 13, And the first plurality of precoding vectors are orthogonal to each other, and the second plurality of precoding vectors are orthogonal to each other. The method of claim 13, The first plurality of precoding vectors are different from the precoding vectors used when precoding the same sync channel preamble among the third plurality of precoding vectors for the sync channel preamble used in the previous frame, And the second plurality of precoding vectors are different from the precoding vectors used when precoding the same broadcast channel among the fourth plurality of precoding vectors for the broadcast channel used in the previous frame. The method of claim 15, The first plurality of precoding vectors are orthogonal to the precoding vectors used when precoding the same sync channel preamble among the third plurality of precoding vectors. And the second plurality of precoding vectors are orthogonal to the precoding vectors used when precoding the same broadcast channel among the fourth plurality of precoding vectors. The method according to any one of claims 12 to 16, And a controller for generating the plurality of synchronization channel preambles, the synchronization channel preamble and broadcast channel multiplexer control signal for determining the plurality of broadcast channels, and the precoding vector multiplexer control signal for selecting the plurality of precoding vectors. Sync channel and broadcast channel transmission apparatus comprising a. The method according to any one of claims 12 to 16, An inverse Fourier transformer for inverse Fourier transforming the precoded plurality of synchronous channel preambles and the plurality of broadcast channels precoded into a transmission signal in a time domain; And And a radio frequency transmitter for transmitting the transmission signal in the time domain.

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