Base station device, user device, and method used in mobile communication system

The present invention relates to a mobile communication system that applies Orthogonal Frequency Division Multiplexing (OFDM) on a downlink, and particularly a base station device, a user device, and a mapping method that effectively map a transmitted signal to a subcarrier. Regarding.

A communication method that succeeds W-CDMA and HSDPA, that is, Long Term Evolution (LTE), has been examined by W-CDMA standardization organization 3GPP, and as a wireless access method, OFDM for downlink and for uplink. SC-FDMA (Single-Carrier Frequency Division Multiplexing) is being studied (see, for example, Non-Patent Document 1).

OFDM is a method in which a frequency band is divided into a plurality of narrow frequency bands (subcarriers), and data is carried on each frequency band for transmission. By arranging them densely without doing anything, high-speed transmission can be realized and frequency utilization efficiency can be improved.

SC-FDMA is a transmission method that can reduce interference between terminals by dividing the frequency band and transmitting between a plurality of terminals using different frequency bands. Since SC-FDMA has the feature that fluctuations in transmission power are small, it is possible to realize low power consumption of terminals and wide coverage.

Generally, in mobile communication, there is a pilot signal for use in channel estimation and measurement of radio quality, and this pilot signal is called a downlink reference signal (DL RS) in LTE.

The downlink reference signal in LTE is represented by a two-dimensional sequence, and is composed of a two-dimensional orthogonal sequence (Orthogonal Sequence) and a two-dimensional pseudo random sequence (Pseudo Random Sequence). The mapping (subcarrier number) of the reference signal to the physical resource is expressed by the following equation (see, for example, Non-Patent Document 2).

<maths num="1"><img file="JP5100747B2_D0001.tif" /></maths>Here, k indicates the subcarrier number, l indicates the OFDM symbol number, and i indicates the slot number. Also,

<maths num="2"><img file="JP5100747B2_D0002.tif" /></maths>Is. m and n take the following integer values.

<maths num="3"><img file="JP5100747B2_D0003.tif" /></maths>here,

<maths num="4"><img file="JP5100747B2_D0004.tif" /></maths>Is the number of subcarriers in the system bandwidth, which is 300 when the system bandwidth is 5 MHz, 600 when the system bandwidth is 10 MHz, and 1200 when the system bandwidth is 20 MHz. Further, p indicates an antenna port number, and p = 0 when only one antenna is used, but p = 0,1,2,3 can be taken when four antennas can be used.

In the above formula, the value of ν is determined by the following formula.

<maths num="5"><img file="JP5100747B2_D0005.tif" /></maths>Where f_hop(j) is a series of cell-specific integers, and represents a hopping pattern that changes for each subframe or slot of the downlink reference signal. That is, f for each cell_hopBy changing (j), it becomes possible to map the downlink reference signal to a different subcarrier for each cell. When the number of subframes in one radio frame is 10, the value of j is 0,1,2, ..., 9. That is, f_hop(j) is a series with 10 elements.

In addition, f_hop(j) may be a fixed value regardless of time. When such a fixed value is set for each cell, the downlink reference signal is a mapping shifted by a fixed value different for each cell.

1A and 1B show an example of mapping the reference signal. Set the antenna port number to 0 (p = 0) and f_hopMapping to physical resources when the element of (j) is always 0 (Fig. 1A), antenna port number is 0 (p = 0), and f_hopThe mapping to physical resources when the element of (j) is always 2 (Fig. 1B) is shown. In the former case, as shown, the downlink reference signal is mapped to the k = 6 × j (integer greater than or equal to j: 0) th subcarrier in the first OFDM symbol (l = 0). However, in the latter case, in the first OFDM symbol (l = 0), the downlink reference signal is mapped to the k = 6 × j + 2 (j: integer greater than or equal to 0) th subcarrier. In addition, in FIG. 1A and FIG. 1B, the case where the number of OFDM symbols per slot is 6 is shown, but instead, the above-mentioned f is also when the number of OFDM symbols per slot is 7._hopSimilar behavior applies to mapping behavior based on (j).

In FIGS. 1A and 1B, f_hopWhen the element of (j) is always 0, and when f_hopTwo examples are shown when the element of (j) is always 2. However, in an actual mobile communication system, there are a large number of cells, and the sequence f of each cell._hop(j) must be set differently from each other. In this case, f_hopIf the element of (j) is always a fixed value, the series f of each cell_hopIt becomes difficult to set (j) to be different from each other.

Series f of each cell above_hopAs the setting method of (j), for example, the cell group ID and the series f_hopIt has been proposed to associate with (j) (see, for example, Non-Patent Document 3). In this case, if the cell group ID is 0 to 5, then f_hopEach element in (j) is always a fixed value, and if the cell group ID is 6 to 169, f_hopDifferent values are set for each element of (j). Then, 170 series f associated with the ID of the above cell group._hop(j) are set to be different from each other. However, series f_hopAlthough each element of (j) is set to be different from each other as much as possible, some of them will be set to the same value.<nplcit num="1"><text>3GPP TR 25.814 (V7.0.0), "Physical Layer Aspects for Evolved UTRA," June 2006</text></nplcit><nplcit num="2"><text>3GPP TR 36.211 (V0.3.1), "Physical Channels and Modulation," November 2006</text></nplcit><nplcit num="3"><text>R1-070894, Cell-specific integer sequences for frequency positioning of DL RS, February, 2007</text></nplcit>

<p> As mentioned above, the cell-specific series f_hop(j) represents a hopping pattern that changes from subframe to slot or slot to downlink reference signal, and must be set differently from each other.</p><p> In the method proposed in Non-Patent Document 3, the cell-specific series f_hop(j) is associated with the ID of the cell group and consists of 6 series in which each element always has a fixed value and 164 series in which the value of each element is not fixed. And these 170 series f_hop(j) are set to be different from each other.</p><p> However, in Non-Patent Document 3, 170 series f_hopAlthough (j) is defined so that each element of the series is as different as possible from each other, not all the elements are necessarily different. From the point of view of transmission characteristics, for example, the sequence f of two adjacent cells_hopIt is desirable that (j) are completely different from each other.</p><p> Therefore, the present invention presents a series f of two adjacent cells._hopIt is an object of the present invention to define (j) so as to be different from each other with a higher probability, and as a result, to provide a base station apparatus, a user apparatus, and a method used in them, which can improve transmission characteristics.</p>

<p> In order to realize the above problems, in the present invention, the mapping pattern sequence f_hop(j) is composed of a two-stage (two-layer) series, for example, a first layer composed of a random hopping pattern and a second layer composed of a shift pattern representing a fixed shift amount.</p><p> More specifically, a first aspect of the present invention provides a base station apparatus in a mobile communication system that uses Orthogonal Frequency Division Multiplexing (OFDM) for the downlink. This base station device Means to generate the first signal and Means to generate the second signal and A means for generating a transmission symbol by multiplexing the first signal and the second signal and mapping them to subcarriers. A mapping determination means for determining the mapping position of the second signal to the subcarrier, and The mapping determination means determines the mapping position based on the cell ID or the cell group ID and the mapping pattern defined by the sequence of the two-stage structure.</p><p> The first signal is, for example, a data signal including user data or control data, and the second signal is, for example, a reference signal.</p><p> The mapping pattern defined by the series of the two-stage structure is defined by, for example, a series of the first layer composed of a random hopping pattern and a series of the second layer representing shifting having a fixed shift amount. Random.</p><p> A second aspect provides user equipment in a mobile communication system that uses Orthogonal Frequency Division Multiplexing (OFDM) for downlinks. The user device is A means for Fourier transforming the signal received from the base station device and deriving the received symbol, A means for separating the first signal and the second signal from the received symbol, A mapping information management unit that obtains mapping information on the subcarrier of the second signal and supplies the mapping information to the separation means. A means for performing channel estimation using the second signal and demodulating the first signal, and Have, The mapping information management unit stores in advance the correspondence between the cell ID or cell group ID and the mapping pattern defined in the two-stage series, and stores the cell ID of the cell in which the user device is located or the cell to which the cell belongs. The mapping pattern is detected based on the ID of the group, and the detected mapping pattern is supplied to the separation means.</p><p> A third aspect provides a method of mapping signals to subcarriers in mobile communication systems that use Orthogonal Frequency Division Multiplexing (OFDM) for downlinks. In this method, when the first signal and the second signal are multiplexed in a base station apparatus and mapped to a subcarrier to generate a transmission symbol, the second signal is randomly combined with a cell ID or a cell group ID. It maps to the subcarrier position determined by the mapping pattern defined by the two-stage series of the first series composed of various hopping patterns and the second series representing shifting having a fixed shift amount.</p><p> In a good embodiment, the mapping pattern is associated with the cell ID or cell group ID to define a sequence of the random hopping patterns and the fixed function associated with the cell ID or cell group ID. It is defined by the sum of the second function that defines the shift pattern sequence of the shift amount.</p>

<p> According to the above configuration and method, there is a high probability that the mapping positions of the reference signals of adjacent cells are different from each other, and as a result, it is possible to realize downlink wireless communication having good transmission characteristics.</p>

<figref num="1A">It is a figure which shows the mapping example of the downlink reference signal.</figref><figref num="1B">It is a figure which shows the mapping example of the downlink reference signal.</figref><figref num="2">It is a block diagram which shows the structure of the mobile communication system which concerns on embodiment of this invention.</figref><figref num="3">It is explanatory drawing which shows the structure of the subframe.</figref><figref num="4">It is a schematic block diagram of the base station apparatus which concerns on one Example of this invention.</figref><figref num="5">F according to an embodiment of the present invention _hopIt is a conceptual diagram of (j).</figref><figref num="6">This is an example of cell arrangement of a mobile communication system according to an embodiment of the present invention.</figref><figref num="7">It is a schematic block diagram of the user apparatus which concerns on one Example of this invention.</figref>

Code description

50 cells 100₁,100₂,100₃,100_n User device 102 Analog-to-digital converter (A / D) 104 CP remover 106 Fast Fourier Transform (FFT) 108 Separation (DeMUX) 110 Multiplying part 112 Multiplying part 114 channel estimator 116 Demodulator 118 Reference signal mapping information management department 200 base station equipment 202 Data signal processing unit 2021 MCS setting section 2022 encoder 2023 data modulator 2024 Interleaver 204 Series-parallel converter (S / P) 206 Multiplexer (MUX) 208 Fast Inverse Fourier Transform (IFFT) 210 CP addition part 212 Digital-to-analog converter (D / A) 214 Reference signal generator 2141 Multiplying part 2142 Multiplying part 216 Reference signal mapping determination unit 300 Access gateway device 400 core network

Next, the best mode for carrying out the present invention will be described with reference to the drawings based on the following examples. In all the drawings for explaining the examples, those having the same function use the same reference numerals, and the repeated description will be omitted.

A mobile communication system to which the base station apparatus according to the embodiment of the present invention is applied will be described with reference to FIG.

The mobile communication system 1000 is a system to which, for example, Evolved UTRA and UTRAN (also known as Long Term Evolution, or Super 3G) is applied, and is a base station device (eNB: eNode B) 200 and a plurality of user devices (UE: User). Equipment) 100_n(100₁、100₂、100₃、・・・100_n, N is an integer of n&gt; 0). The base station apparatus 200 is connected to a higher-level station, for example, the access gateway apparatus 300, and the access gateway apparatus 300 is connected to the core network 400. Here, the user device 100_nCommunicates with the base station apparatus 200 in cell 50 by Evolved UTRA and UTRAN.

Each user device (100₁、100₂、100₃、・・・100_n) Have the same configuration, function, and state. Therefore, unless otherwise specified, the user device 100 is described below._nI will proceed with the explanation. For convenience of explanation, it is the user device that wirelessly communicates with the base station device, but more generally, it includes both mobile terminals and fixed terminals.

The mobile communication system 1000 can operate with a plurality of variable bandwidths. As an example, such variable bandwidths are provided such as 5MHz, 10MHz and 20MHz. An operator operates one or more of the variable bandwidths as the system bandwidth, and the user in the system has one or more resource blocks (for example, 25 resource blocks in the 5 MHz system bandwidth). Can be used for communication.

The mobile communication system 1000 uses OFDM (Orthogonal Frequency Division Multiple Access) for downlink and SC-FDMA (Single Carrier-Frequency Division Multiple Access) for uplink as wireless access methods. As described above, OFDM is a method in which a frequency band is divided into a plurality of narrow frequency bands (subcarriers), and data is placed on each frequency band for transmission. SC-FDMA is a transmission method that can reduce interference between terminals by dividing the frequency band and transmitting between a plurality of terminals using different frequency bands.

For downlink, each user device 100_nA physical downlink shared channel (PDSCH) shared and used in LTE and a downlink control channel for LTE are used. The downlink control channel for LTE is called a physical downlink control channel (PDCCH). The physical downlink control channel is also referred to as a downlink L1 / L2 control channel (DL L1 / L2 Control Channel). The downlink data signal is transmitted by the physical downlink shared channel. The data signal is referred to as a Downlink-Shared Channel as a transport channel.

For uplink, each user device 100_nA physical uplink shared channel (PUSCH) shared and used in LTE and an uplink control channel for LTE are used. There are two types of uplink control channels: a channel that is time-multiplexed to a physical uplink shared channel and a channel that is frequency-multiplexed. The latter is transmitted in a band prepared exclusively for the physical uplink shared channel. The uplink data signal is transmitted by the physical uplink shared channel. The data signal is referred to as an Uplink-Shared Channel as a transport channel.

In the uplink, the uplink quality indicator (CQI: Channel Quality Indicator) and the delivery confirmation information of the physical downlink shared channel (Downlink Shared Channel (DL-SCH) as a transport channel) are used by the uplink control channel for LTE (CQI: Channel Quality Indicator). HARQ ACK information) is transmitted. The downlink quality information (CQI) is also used to determine the resource allocation (scheduling) of physical downlink shared channels and the transport format in Adaptive Modulation and Coding (AMC).

Figure 3 shows the configuration of subframes on the downlink. As illustrated in the figure, one subframe is, for example, 1 ms, and one subframe contains, for example, 14 OFDM symbols. The physical downlink control channel is mapped to some OFDM symbols from the beginning of one subframe. The maximum number of OFDM symbols to which a physical downlink control channel is mapped is 3. Physical downlink control channels are (1) mapped to OFDM symbols # 1, (2) mapped to OFDM symbols # 1 and # 2, and (3) mapped to OFDM symbols # 1, # 2, and # 3. It is mapped in three ways. In the example of FIG. 3, the physical downlink control channel is mapped to the first two OFDM symbols (# 1 and # 2) of one subframe. Then, in the OFDM symbol to which the physical downlink control channel is not mapped, a data signal (physical downlink shared channel PDSCH as a physical channel, DL-SCH as a transport channel) or a synchronization channel (Synchronization) Channel or Synchronization Signal, SCH), broadcast channel (BCH), etc. are transmitted. The broadcast channel may be referred to as, for example, Physical BCH.

In addition, M resource blocks (RB: Resource Block) are prepared in the frequency direction. As an example, the frequency band per resource block is 180kHz, and there are 12 subcarriers in one resource block. For convenience of explanation, a resource that occupies the bandwidth of one subcarrier and the period of one OFDM symbol is called a "resource element". The number M of resource blocks is 25 when the system bandwidth is 5 MHz, 50 when the system bandwidth is 10 MHz, and 100 when the system bandwidth is 20 MHz.

FIG. 4 shows a schematic block diagram of the base station apparatus 200 according to the embodiment of the present invention. The base station apparatus 200 includes a data signal processing unit 202, a series-parallel conversion unit (S / P) 204, a multiplex unit (MUX) 206, a fast inverse Fourier transform unit (IFFT) 208, and a cyclic prefix (CP). It has an additional unit 210, a digital-analog conversion unit (D / A) 212, a reference signal generation unit 214, and a reference signal mapping determination unit 216. The data signal processing unit 202 includes an MCS setting unit 2021, a encoder 2022, a data modulator 2023, and an interleaver 2024. The reference signal generation unit 214 has a multiplication unit 2141 and a multiplication unit 2142.

The data signal processing unit 202 performs processing related to data signals addressed to individual users.

The MCS setting unit 2021 instructs each processing element to change the combination of the modulation method and the coding rate used for the data signal as needed. The combination of the modulation method and the coding rate may be specified by a number (MCS number) indicating the content of the combination.

The encoder 2022 performs channel coding to increase the error tolerance of the data signal. The coding may be performed by various methods well known in the art such as convolutional coding and turbo coding. In this embodiment, adaptive modulation and coding (AMC) control is performed on the data signal, and the channel coding rate is adaptively changed according to an instruction from the MCS setting unit 2021.

The data modulator 2023 performs data modulation of the data signal by some suitable modulation method such as QPSK, 16QAM, 64QAM and the like. In this embodiment, AMC control is performed on the data signal, and the modulation method is adaptively changed according to the instruction from the MCS setting unit 2021.

The interleaver 2024 rearranges the order of the bits contained in the data signal according to a predetermined pattern. Alternatively, the interleaver 2024 may perform the process of rearranging the order in which the bits are arranged, and instead perform the process of doing nothing. In this case, the order in which the bits are arranged remains the same.

Although the processing elements for the control channel are not specified in FIG. 4, the same processing as for the data signal processing unit 202 is performed for the control channel. However, AMC control may not be performed on the control channel.

The series-parallel conversion unit (S / P) 204 converts a series signal sequence (stream) into a parallel signal sequence. The number of parallel signal sequences may be determined according to the number of subcarriers.

The multiplexing unit (MUX) 206 multiplexes the data series representing the output signal from the series-parallel conversion unit (S / P) 204 and the reference signal. The multiplexing may be performed by any method of time multiplexing, frequency multiplexing, or time and frequency multiplexing. In addition to the above data series and the reference signal, the broadcast channel may be multiplexed. Here, the multiplexing unit (MUX) 206 receives the mapping information of the reference signal of the subframe from the reference signal mapping determination unit 216, and multiplexes the data series and the reference signal based on the mapping information. To do. That is, the multiplexing unit (MUX) 206 maps the data series and the reference signal to the subcarriers based on the mapping information.

The fast inverse Fourier transform unit (IFFT) 208 performs a fast inverse Fourier transform on the signal input thereto and performs OFDM modulation.

The CP addition unit 210 creates a transmission symbol by adding a Cyclic Prefix (CP) to the modulated symbol of the OFDM method. There are two types of CP length (CP length), Long CP and Short CP, and which CP length is used is selected for each cell.

The digital-to-analog converter (D / A) 212 converts a baseband digital signal into an analog signal.

The reference signal generation unit 214 multiplies a reference signal (referred to as a reference signal for convenience) by a random code sequence which is the first sequence and an orthogonal code sequence which is the second sequence, and obtains a reference signal. prepare. How the reference signal is prepared is described in Chapter 5.6 of Non-Patent Document 2. In the above example, the random code sequence which is the first sequence and the orthogonal code sequence which is the second sequence are multiplied, but instead, only the random code sequence which is the first sequence is multiplied. May be good.

The reference signal mapping determination unit 216 determines to which subcarrier the reference signal is mapped in the subframe of the cell, and multiplexes (MUX) 206 the mapping information of the determined reference signal to the subcarrier. Notify to.

The details of the method of determining the subcarrier to which the reference signal is mapped in the reference signal mapping determination unit 216 will be described below.

As explained in the background art, the subcarriers to which the downlink reference signal is mapped are cell-specific sequences f._hopDetermined by defining (j). j is an index representing a subframe in one radio frame. Since one radio frame is 10 ms, it can take values of j = 0,1,2,3,4,5,6,7,8,9.

The reference signal mapping determination unit 216 is, for example, as shown in FIG. 5, a cell-specific sequence f representing a hopping pattern for each subframe._hop(j) is defined as follows.

<maths num="6"><img file="JP5100747B2_D0006.tif" /></maths>Where the ID_gIs the ID of the cell group. Function of the first term

<maths num="7"><img file="JP5100747B2_D0007.tif" /></maths>Is a random series having a cell group ID as an argument, and determines a hopping pattern. The series represented by the function of the first term is the first layer of the two-stage structure (or two-layer structure). The number of cell group IDs is 170 and the IDs_gSince 0, 1, 2, ..., 169 are set as the values of, the function

<maths num="8"><img file="JP5100747B2_D0008.tif" /></maths>, 29 kinds of hopping patterns may be defined. More specifically, the functions of the first layer

<maths num="9"><img file="JP5100747B2_D0009.tif" /></maths>In

<maths num="10"><img file="JP5100747B2_D0010.tif" /></maths>29 types may be defined. The function

<maths num="11"><img file="JP5100747B2_D0011.tif" /></maths>Is preferably set in consideration of the amount of hopping between subframes adjacent in time. For example, the amount of hopping between temporally adjacent subframes may be limited to 0, 1 or 5. In other words, the amount of hopping between subframes may be limited to a predetermined threshold value or less (in this case, 1 or less). Note that a hopping amount of 5 is substantially the same as a hopping amount in the minus direction of 1. By limiting in this way, the channel estimation accuracy can be improved. In addition, the function

<maths num="12"><img file="JP5100747B2_D0012.tif" /></maths>It is desirable to consider the amount of hopping between the last subframe of a certain radio frame and the first subframe of the next radio frame when generating. For example, the amount of hopping between the last subframe of one radio frame and the first subframe of the next radio frame may also be limited to 0, 1 or 5. In other words, the amount of hopping between the last subframe of a radio frame and the first subframe of the next radio frame may be limited to a predetermined threshold or less (in this case, 1 or less). Alternatively, conversely, the amount of hopping between temporally adjacent subframes may be limited to 2, 3 or 4. The above values of 0, 1, 2, 3, 4, and 5 are values in consideration of the fact that the final hopping amount is the remainder divided by 6. Therefore, in practice, a value of 6 or more may be defined. Even when a value of 6 or more is defined, it is desirable that the above limitations apply to the remainder when divided by 6.

Function b (ID) in the second term_g) Is the function of the first item

<maths num="13"><img file="JP5100747B2_D0013.tif" /></maths>Is a function that performs fixed shifting, for example, b (ID_g) = ID_g% 6 Is defined as. Here, A% B means the remainder obtained by dividing A by B. In other words, the function b (ID) of the second item_g) Is the function of the first item

<maths num="14"><img file="JP5100747B2_D0014.tif" /></maths>Determine a fixed shift amount for. The series represented by the function that determines the fixed shift amount is defined as the second layer series of the two-stage structure (two-layer structure).

In this way, the positions of the subcarriers to which the reference signal is mapped can be hierarchically or hierarchically determined by the first function a (x, j) and the second function b (y), both of which take the ID of the cell group as an argument. Function f represented by a tree structure_hopDetermined by (j). And the above function f_hopBased on the reference signal mapping information determined in (j), the multiplexer (MUX) 206 maps the data signal and the reference signal to the subcarriers.

More specifically, for example, consider the following case as a function a (x, j). a (0, 0) = 7 a (0, 1) = 4 a (0, 2) = 1 a (0, 3) = 7 a (0, 4) = 1 a (0, 5) = 5 a (0, 6) = 0 a (0, 7) = 4 a (0, 8) = 2 a (0, 9) = 2 In this case, f in the cell where the cell group ID is 0_hop(j) is as follows. f_hop (0) = 7 + 0 = 7 f_hop (1) = 4 + 0 = 4 f_hop (2) = 1 + 0 = 1 f_hop (3) = 7 + 0 = 7 f_hop (4) = 1 + 0 = 1 f_hop (5) = 5 + 0 = 5 f_hop (6) = 0 + 0 = 0 f_hop (7) = 4 + 0 = 4 f_hop (8) = 2 + 0 = 2 f_hop (9) = 2 + 0 = 2 Also, f in the cell whose cell group ID is 2._hop(j) is as follows. f_hop (0) = 7 + 2 = 9 f_hop (1) = 4 + 2 = 6 f_hop (2) = 1 + 2 = 3 f_hop (3) = 7 + 2 = 9 f_hop (4) = 1 + 2 = 3 f_hop (5) = 5 + 2 = 7 f_hop (6) = 0 + 2 = 2 f_hop (7) = 4 + 2 = 6 f_hop (8) = 2 + 2 = 4 f_hop (9) = 2 + 2 = 4 As a result, f in the cell whose cell group ID is 0_hop(j) and f in the cell whose cell group ID is 2._hopWith (j), each element is set to be different from each other. The same is true for cells with cell group IDs 0, 1, 2, 3, 4, and 5. That is, f in cells whose cell group IDs are 0, 1, 2, 3, 4, and 5._hop(j) is set so that its elements are different from each other.

Similarly, if we define a (1, j), a (2, j), ..., f in the cell whose cell group ID is 6,7,8,9,10,11._hop(j) is set so that each element is different from each other, and f in the cell whose cell group ID is 12,13,14,15,16,17._hop(j) is set so that its elements are different from each other. Below, the same applies to cells with cell ID 169.

Here, in the mobile communication system 1000, for example, as shown in FIG. 6, cell groups having the same x value of a (x, j), which is a series for randomly determining a hopping pattern, are adjacent to each other. You may arrange cells. In FIG. 6, cell groups with x = 0, that is, cell groups with cell group IDs 0,1,2,3,4,5,6 are arranged so as to be adjacent to each other. In addition, cell groups with x = 1, that is, cell groups with cell group IDs 6,7,8,9,10,11 are arranged so as to be adjacent to each other. As described above, in the mobile communication system 1000, cell groups having the same series a (x, j) of the first layer that determines the hopping pattern may be arranged so as to be adjacent to each other.

By arranging cell groups having the same a (x, j) that determine the hopping pattern so as to be adjacent to each other, it is possible to reduce the probability of collision of refunless signals between adjacent cells, and as a result, Transmission characteristics are improved.

FIG. 7 shows the user device 100 according to the embodiment of the present invention._nThe outline block of is shown. User device 100_nIs an analog-to-digital converter (A / D) 102, a CP removal unit 104, a fast Fourier transform unit (FFT) 106, a separation unit (DeMUX) 108, a multiplication unit 110, a multiplication unit 112, and a channel estimation. It includes a unit 114, a demodulation unit 116, and a reference signal mapping information management unit 118.

The analog-to-digital converter (A / D) 102 converts the received baseband analog signal into a digital signal.

The CP removal unit 104 removes the CP from the received symbol and leaves the valid symbol part.

The fast Fourier transform unit (FFT) 106 performs a fast Fourier transform on the input signal and demodulates the OFDM method.

Separator (DeMUX) 108 separates the reference signal and the data signal (user data or control data) from the received signal. Here, the separation unit (DeMUX) 108 receives information on which subcarrier the reference signal is mapped to in the subframe from the reference signal mapping information management unit 118, and based on the above information, from the received signal. Separate the reference signal and the data signal (user data or control data).

The multiplication units 110 and 112 multiply the reference signal by the random code sequence which is the first sequence and the orthogonal code sequence which is the second sequence. In the above example, the random code sequence which is the first sequence and the orthogonal code sequence which is the second sequence are multiplied, but instead, only the random code sequence which is the first sequence is multiplied. May be good.

The channel estimation unit 114 performs channel estimation based on the reference signal, and determines what kind of channel compensation should be applied to the received data signal.

The demodulation unit 116 compensates the data signal based on the channel estimation result, and restores the data signal transmitted from the base station apparatus 200.

In the reference signal mapping information management unit 118, the cell group ID and the cell-specific series f_hopInformation indicating the relationship with (j) has been acquired in advance. Then, the reference signal mapping information management unit 118 fs based on the communication area provided by the base station apparatus 200 with which the station is communicating, that is, the ID of the cell group to which the cell belongs._hopGet (j). f_hopSince the details of (j) are the same as the above-described description of the reference signal mapping determination unit 216, they will be omitted. The reference signal mapping information management unit 118 is f based on the cell group ID._hopGet (j) and f above_hopBased on (j), information on which subcarrier the reference signal is mapped to in the subframe is generated and notified to the separation unit (DeMUX) 108.

In the above example, the subcarrier to which the reference signal is mapped is determined based on the cell group ID and the sequence of the two-stage structure, but the cell ID is used instead of the cell group ID. May be done. That is, the subcarrier to which the reference signal is mapped may be determined based on the cell ID and the sequence of the two-stage structure.

In the above-described embodiment, an example in a system to which Evolved UTRA and UTRAN (also known as Long Term Evolution, or Super 3G) is applied has been described. It can be applied to all systems that use the OFDM method in the link.

Thus, according to an embodiment of the present invention, 170 series f_hop(j) is defined as a series with a two-layer structure, and the series f of two adjacent cells._hopBy making (j) different from each other with a higher probability, it becomes possible to realize downlink wireless communication with good transmission characteristics.

This international application claims priority based on Japanese Patent Application No. 2007-073731 filed on March 20, 2007, the entire contents of which are incorporated into this international application.