KR100937028B1 - Signal transmission method and downlink frame generation method - Google Patents

Abstract

In the signal transmission method, a plurality of first phase values and a plurality of second phase values respectively corresponding to a plurality of antennas are applied to a broadcast channel (or forward shared data / control channel) symbol, respectively, and a plurality of signals corresponding to the plurality of antennas respectively. Generating a transmission signal, and transmitting the plurality of transmission signals through the plurality of antennas, respectively, wherein the plurality of second phase values are determined according to a sector in which the broadcast channel symbol is transmitted. Accordingly, by applying the precoding vector switching diversity scheme to the broadcast channel information, it is possible to maximize the time diversity gain within the transmission time interval of the broadcast channel information and to efficiently remove interference from adjacent sectors at the sector boundary.

SCH, BCH, Sector, Precoding Vector, Antenna, Phase Shift Value

Description

Signal transmission method and downlink frame generation method {METHOD FOR TRANSMITTING SIGNAL AND METHOD FOR MANUFACURING DOWNLINK FRAME}

The present invention relates to a signal transmission method and a downlink frame generation method.

The present invention is derived from 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 Communication Research and Development. .

Currently, 3GPP (3rd Generation Partnership Project) standardization of wireless transmission technology based on orthogonal frequency division multiplexing (OFDM) under the name of 3G Long Term Evolution (LTE).

In a multi-cell system using OFDM, a user should be able to efficiently receive information necessary for initial system access through a broadcast channel. In addition, all users in any sector must satisfy the requirements for reception quality of broadcast channel information, for example, block error rate and delay rate.

However, when a user is at a sector boundary within the same cell, there is a problem that this requirement is not satisfied due to the interference from adjacent sectors.

An object of the present invention is to provide a transmission diversity method for effective demodulation of broadcast channel (or forward data channel / control channel) information. Another object of the present invention is to provide a signal transmission method for improving reception quality of broadcast channel information of a mobile station at a sector boundary of a cell.

The signal transmission method according to the present invention generates a plurality of transmission signals corresponding to the plurality of antennas by applying a plurality of first phase values and a plurality of second phase values respectively corresponding to a plurality of antennas to a broadcast channel symbol. And transmitting the plurality of transmission signals through the plurality of antennas, respectively, wherein the plurality of second phase values are determined according to sectors in which the broadcast channel symbol is transmitted.

One frame includes a plurality of subframes, and the broadcast channel symbol may be assigned to at least two subframes.

The plurality of first phase values may have different values according to the subframes to which the broadcast channel symbols are allocated.

One frame includes a plurality of subframes, and the broadcast channel symbol may be assigned to only one of the plurality of subframes.

The plurality of first phase values may have different values according to symbol intervals of the subframe to which the broadcast channel symbol is allocated.

The plurality of first phase values may have the same value for all sectors.

In addition, the method for generating a downlink frame according to the present invention includes applying a plurality of first phase values and a plurality of second phase values corresponding to a plurality of antennas, respectively, the plurality of first phase values and the plurality of second phases. Applying a phase value to a plurality of broadcast channel symbols, and disposing the plurality of broadcast channel symbols in a plurality of broadcast channel symbol intervals, wherein the plurality of second phase values include: It is determined according to the sector to be transmitted and applied to the plurality of broadcast channel symbols.

The plurality of first phase values may be determined according to broadcast channel symbol intervals.

The plurality of broadcast channel symbol intervals may be allocated to only one subframe.

The plurality of second phase values may have 0 for one of the plurality of antennas.

According to the present invention, a precoding vector switching diversity scheme is applied to broadcast channel (or forward data channel / control channel) information to maximize time diversity gain within a transmission time interval (TTI) of broadcast channel information. At the same time, interference from adjacent sectors at the sector boundary can be efficiently removed.

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”, “… unit”, “module”, etc. 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. have.

In this specification, a mobile station (MS) includes a terminal, a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), and a 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) is an access point (AP), a radio access station (Radio Access Station, RAS), a Node B (Node B), a base transceiver station (Base Transceiver Station, BTS), MMR ( Mobile Multihop Relay) -BS and the like, and may include all or part of functions such as an access point, a radio access station, a Node B, a base transceiver station, and an MMR-BS.

Hereinafter, a communication system according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

1 is a diagram illustrating a communication system according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a base station according to an embodiment of the present invention.

Referring to FIG. 1, the communication system includes a base station 100 and a mobile station 200. Referring to FIG. 2, the base station 100 includes a first sector transmitter 110, a second sector transmitter 120, and The third sector transmitter 130 is included.

Base station 100 manages cell 10. The cell 10 is composed of a first sector 11, a second sector 12, and a third sector 13. In the embodiment of the present invention, the cell 10 is described as being composed of three sectors. Alternatively, the cell 10 may be composed of two or four sectors. Base station 100 communicates with mobile station 200 within cell 10.

The first sector transmitter 110, the second sector transmitter 120, and the third sector transmitter 130 manage the first sector 11, the second sector 12, and the third sector 13, respectively. . That is, the first sector transmitter 110 communicates with the mobile station in the first sector 11, the second sector transmitter 120 communicates with the mobile station in the second sector 12, and the third sector transmitter 130 Communicate with the mobile station in the third sector 13.

The first sector transmitter 110, the second sector transmitter 120, and the third sector transmitter 130 each have a synchronization channel (eg, a first sector 11, a second sector 12, and a third sector 13). Synchronization channel (SCH) information and broadcast channel (BCH) information are transmitted. SCH information varies from sector to sector, and BCH information is common to all sectors. That is, SCH information is distinguished according to sectors, and BCH information is distinguished according to cells. The BCH information is transmitted on a predefined independent physical channel known to all mobile stations 200. The first sector transmitter 110, the second sector transmitter 120, and the third sector transmitter 130 are synchronized so that the mobile station 200 can demodulate the BCH information through soft-combining.

In an embodiment of the present invention, a sector to which the mobile station 200 belongs to among the plurality of sectors constituting the cell 10 is called a home sector, and the received power of a threshold value or more adjacent to the mobile station among the sectors excluding the home sector. A sector for transmitting a signal is called a target sector.

Hereinafter, a sector transmitter and a signal transmission method according to an embodiment of the present invention will be described with reference to FIGS. 3 to 8.

3 is a block diagram illustrating a sector transmitter according to an embodiment of the present invention.

Referring to FIG. 3, a sector transmitter 400 according to an embodiment of the present invention transmits a signal to an s-th sector, and includes a BCH symbol generator 410, a SCH symbol generator 420, and other channel symbol generators. 430, the first transmitter 440a, the second transmitter 440b, the precoding vector switch 450, the sector-specific precoding vector table 451, and the first / second antennas 460a / 460b. Include.

The BCH symbol generator 410 includes a channel encoder 411, an interleaver 412, and a digital modulator 413.

4 is a flowchart illustrating a sector transmission method according to an embodiment of the present invention.

First, the BCH symbol generator 410 generates and outputs a plurality of BCH symbols.

In detail, the channel encoder 411 performs channel coding such as turbo coding or convolutional coding on the BCH data to generate and output channel encoded BCH data (S201).

The interleaver 412 generates and outputs interleaved BCH data by changing the order of channel encoded BCH data output by the channel encoder 411.

The digital modulator 413 performs digital modulation such as binary phase shift key (BPSK) and quadrature amplitude modulation (QAM) on the interleaved BCH data output from the interleaver 412. A plurality of BCH symbols are generated and output (S201).

등이 될 수 있다.On the other hand, the SCH symbol generation unit 420 generates and outputs a plurality of SCH symbols (S203). The SCH symbol generator 420 generates and outputs an SCH symbol vector by scrambling the SCH symbol using an SCH scrambling code according to the number of SCH symbols included in the subframe s in which the SCH symbol exists. The value of the SCH symbol can be changed according to the specification, 1 or

And so on.

On the other hand, the other channel symbol generator 430 generates and outputs a plurality of other channel symbols (S205).

The precoding vector switch 450 applies the precoding vector to the corresponding BCH symbol so that a plurality of BCH symbols can be transmitted through the corresponding antenna according to the sector-specific precoding vector table 451, and outputs the SCH symbol and the like. The channel symbols are also switched and output to the first and second transmitters 440a and 440b (S207).

At this time, the SCH symbol adjacent to the BCH symbol is transmitted to the same first and second transmitters 440a and 440b as the adjacent BCH symbol.

Hereinafter, a transmission diversity scheme by precoding vector switching will be described with reference to FIGS. 5 and 6.

5 and 6 are cell configuration diagrams according to a precoding vector switching technique.

In FIG. 5 and FIG. 6, it is assumed that each sector transmitter has two or four antennas 460a and 460b, and one cell includes three sectors.

The precoding vector switch 450 applies a precoding vector to the BCH symbol, B _{k, i, c} (s) in the subframes containing the BCH symbol as shown in Equation 1, and transmits a signal for each transmission antenna a, T _k. produces _{i, a, c} (s).

[Equation 1]

Here, k denotes a frequency domain subcarrier index containing BCH information B _{k , i, c} (s) for each sector c. In addition, Ø _{1, 0} (i, s) denotes a phase weighting value of a precoding vector applied to a BCH symbol in a symbol i of a subframe s containing a BCH symbol, and at the same time, a phase for maximizing time diversity gain. Means the variation value.

In this case, a relationship of Ø _1,0 (i, s) = 0 and Ø _{1, a} (i, s) = a · Ø _1,1 (i, s) may be satisfied.

As shown in FIG. 5, the precoding vector switch 450 may apply a phase value of the same precoding vector to all sectors c included in each cell 10.

Meanwhile, the precoding vector switch 450 may apply a phase value according to sector c of each cell 10 as shown in FIG. 6.

That is, the precoding vector has a phase value determined according to the transmission antenna a and the sector c in the corresponding subframe s.

The transmission signal per transmission antenna, T _{k, i, a, c} (s) (a = 1,2) output through the precoding vector switch 450 satisfies Equation 2.

[Equation 2]

At this time, Ø _{2, a} (c) = a · Ø _{2, 1} (c) can be satisfied.

For example, if the number of sectors c in the cell is 3, Ø _{2, a} (0) = 0, Ø _{2, a} (1) = 2π / 3, Ø _{2, a} (2) = 4π / 3 Ø _{2, a} (c) may be applied as 0, π, π / 2 (-π / 2) depending on the sector. Further, when the number of sectors c in the cell is 6, the case where the number of sectors c is 3 is extended so that Ø _{2, a} (s) is 0, 2π / 3, 4π / 3, 0, 2π / 3, 4π / 3, or 0, π, π / 2,3π / 2,0, π or π / 2,3π / 2,0, π, π / 2,3π / 2 Can be.

When different phase shifts are applied between sectors, even if the phase weighting value according to the precoding vector and the phase shifting value for temporal diversity are the same, the phase shifting value for the spatial diversity gain is different for each sector. When the spatial correlation between antennas is relatively large, different beams are formed. Therefore, interference from adjacent sectors can be effectively prevented.

As such, the sector transmitter 400 applies precoding vector switching to the BCH symbol to lower the block error rate of the BCH information to improve reception quality.

Meanwhile, the precoding vector switch 450 performs a time-switch transmit while performing switching so that a plurality of BCH symbols and SCH symbols adjacent in time to the plurality of BCH symbols can be transmitted through the same antenna. diversity, TSTD) or frequency-switch transmit diversity (FSTD) may be applied to the SCH and the BCH. For example, the precoding vector switch 460 transfers the SCH symbol and the BCH symbol for some subcarriers to the first transmitter 440a, and the SCH symbol and the BCH symbol for other subcarriers, and the second transmitter 440b. To pass).

The precoding vector switch 450 may apply the TSTD and the FSTD to the SCH and the BCH simultaneously while performing switching so that the plurality of BCH symbols and SCH symbols adjacent in time to the plurality of BCH symbols can be transmitted through the same antenna. have.

The first and second transmitters 440a and 440b receive a plurality of channel symbols from the precoding vector switch 450 to generate OFDM symbols, and generate c times through the first and second antennas 460a and 460b. Transfer to sector.

In detail, the first and second transmitters 440a and 440b output a plurality of mapped symbols by mapping a plurality of BCH symbols, a plurality of SCH symbols, and a plurality of other channel symbols to the time domain and the frequency domain (S209). ). That is, the first and second transmitters 440a and 440b may include an OFDM mapping unit (not shown) for each mapping, and may include a plurality of BCH symbols, a plurality of SCH symbols, and a plurality of other channel symbols. Time division multiplexing and frequency division multiplexing.

Hereinafter, a mapping method of the first and second transmitters 440a and 440b will be described with reference to FIGS. 7 and 8.

7 and 8 illustrate downlink frames in which SCHs and BCHs are mapped according to various embodiments of the present disclosure.

The sector transmitter 300 may use various bandwidths such as 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, and 20 MHz as the system bandwidth.

7 and 8, a downlink frame according to an embodiment of the present invention is composed of 20 subframes. SCH and BCH are mapped to the same frequency of the system bandwidth, for example, 1.25 MHz. Accordingly, the mobile station 200 does not need to perform blind detection on the BCH bandwidth to demodulate the BCH symbol.

When the number of SCHs is two, one is called a primary synchronous channel (P-SCH) and the other is called a secondary chronization channel (S-SCH).

The first and second OFDM symbol mapping units 441a and 441b allocate a plurality of P-SCH symbols and a plurality of S-SCH symbols to two adjacent OFDM symbol intervals by time division multiplexing (TDM). . In this case, the S-SCH may be used for channel estimation or, alternatively, the P-SCH may be used for channel estimation.

According to FIG. 7, the first and second transmitters 440a and 440b multiplex BCH information into two subframes during one downlink frame period. The BCH information is transmitted to the mobile station 200 in the form of a packet. One BCH information packet may be multiplexed in one frame and transmitted every 10 msec, and may be multiplexed in two or more frames and 20 msec, 30 msec, or 40 msec. May be sent.

An embodiment of the present invention may use a multiplexing method for transmitting BCH information through a unicast channel, or a multiplexing method for transmitting a BCH information through a multicast channel, a multimedia broadcast and multicast service (MBMS) channel, and the like. Can also be used.

According to FIG. 7, the first / second transmitters 440a and 440b map S-SCH symbols and P-SCHSCH symbols in the last OFDM symbol interval of each subframe at intervals of 10 subframes. The first and second transmitters 440a and 440b may perform a BCH symbol, a BCH symbol, and a reference symbol (DL RS) in OFDM symbol intervals other than the OFDM symbol interval in which the S-SCH symbol and the P-SCHSCH symbol are mapped. Signal) Map the symbol.

When BCH symbols are mapped to a plurality of subframes as illustrated in FIG. 7, the precoding vector switch 450 may obtain time diversity by applying different precoding vectors according to the subframes.

Meanwhile, as shown in FIG. 8, the first / second transmitters 440a and 440b may multiplex BCH symbols to only one subframe without multiplexing the BCH symbols to a plurality of subframes during one frame.

That is, the first / second transmitter 440a / 440b may map the BCH symbol only to the first subframe of one frame, for example.

In this case, the precoding vector switch 450 performs the phase shift described above in units of OFDM symbol intervals in which SCH symbols and BCH symbols are multiplexed.

That is, transmission by transmission antenna by applying a precoding vector switching transmission diversity scheme as shown in Equation 1 to the frequency domain BCH symbols B _{k, i, c} (s) in a subframe containing the BCH symbol (s = 0). Generate signals T _{k, i, a, c} (s).

Alternatively, as shown in Equation 2, a transmission signal may be generated by further applying a phase shift value for each sector to ensure spatial diversity.

In _{Tk, i, a, c} (s) of Equation 2 _{, B, which is a} phase shift value of a precoding vector, is BCH symbols i in a subframe s containing BCH information for each antenna a. It means the precoding phase weighting value which is obtained and the phase shift value for maximizing the time diversity gain.

In the example of the present invention, the time diversity gain may be differently applied to have orthogonality in symbol units. That is, phase shift values having orthogonality between symbols are allocated.

As such, when different phase shift values are allocated according to sectors, when BCH information is different between sectors, that is, sector-specific information, interference from adjacent sectors is effectively reduced. In addition, when the BCH information is the same for sectors in the same cell, that is, the information for common cell use, there is an effect of increasing the soft combining gain.

Referring back to FIG. 3, the first / second transmitters 440a and 440b apply a code for obtaining diversity gain with respect to a BCH symbol among the mapped OFDM symbols as shown in FIG. 7 or 8.

Such a code may include phase rotation values to obtain delay diversity and / or random diversity, and the phase rotation values must be properly adjusted to obtain high delay diversity gain between sectors.

Meanwhile, different codes may be allocated to adjacent subcarriers in order to obtain a random diversity gain.

The first and second transmitters 440a and 440b generate and output a plurality of scrambled symbols by scrambling the sector-specific scrambling code or the cell-specific scrambling code to the coded BCH symbols. Since scrambling the SCH symbol may make initial cell search difficult, the SCH symbol is not scrambling with a sector-specific scrambling code or a cell-specific scrambling code.

The first and second transmitters 440a and 440b inverse fast transform the plurality of scrambled symbols to generate a time domain signal and insert a guard interval such as a cyclic prefix (CP). Next, the first and second transmitters 440a and 440b convert the amplified signals into high frequency signals, amplify them, and transmit them to the mobile station 200 through the first and second antennas 460a and 460b.

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 diagram illustrating a communication system according to an embodiment of the present invention.

2 is a diagram illustrating a base station according to an embodiment of the present invention.

3 is a block diagram illustrating a sector transmitter according to an embodiment of the present invention.

4 is a flowchart illustrating a sector transmission method according to an embodiment of the present invention.

5 and 6 are cell configuration diagrams of a delay diversity scheme according to a precoding vector switching scheme.

7 shows bandwidth allocation for SCH and BCH according to one embodiment of the present invention.

8 shows bandwidth allocation for SCH and BCH according to another embodiment of the present invention.

Claims (10)

A signal transmission method of a communication system in which a plurality of sectors form one cell, Generating a plurality of transmission signals respectively corresponding to the plurality of antennas by applying a plurality of first phase values corresponding to the plurality of antennas and a plurality of second phase values respectively corresponding to the plurality of antennas to a broadcast channel symbol Step, and Transmitting the plurality of transmission signals through the plurality of antennas, respectively Including, The plurality of second phase values is determined according to a sector in which the broadcast channel symbol is transmitted among the plurality of sectors. Signal transmission method. The method of claim 1, One frame includes a plurality of subframes, The broadcast channel symbol is allocated to at least two subframes. The method of claim 2, The plurality of first phase values have different values according to the subframes to which the broadcast channel symbols are assigned. The method of claim 1, One frame includes a plurality of subframes, The broadcast channel symbol is assigned to only one of the plurality of subframes. Signal transmission method. The method of claim 4, wherein The plurality of first phase values have different values according to symbol intervals of the subframe to which the broadcast channel symbol is allocated. The method according to claim 3 or 5, And the plurality of first phase values have the same value for the plurality of sectors. A downlink frame generation method of a communication system in which a plurality of sectors form one cell, Applying a plurality of first phase values respectively corresponding to a plurality of antennas and a plurality of second phase values respectively corresponding to the plurality of antennas, Applying the plurality of first phase values and the plurality of second phase values to a plurality of broadcast channel symbols, and Disposing the plurality of broadcast channel symbols in a plurality of broadcast channel symbol intervals; Including; The plurality of second phase values are determined according to a sector in which the plurality of broadcast channel symbols are transmitted among the plurality of sectors, and are applied to the plurality of broadcast channel symbols. The method of claim 7, wherein The plurality of first phase values are determined according to a broadcast channel symbol interval. The method of claim 8, And a plurality of broadcast channel symbol intervals are allocated to only one subframe. The method of claim 9, And the plurality of second phase values has zero for one of the plurality of antennas.

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