JPWO2007023917A1 - Wireless communication method and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine a propagation path with high accuracy even in the vicinity of an edge of a sector in an OFDM communication system, and to prevent a communication performance of the entire system from deteriorating even when there is a terminal that cannot perform MIMO reception. Generate and send a pattern. A wireless communication method based on an OFDM communication method, in which a code string used for estimating a propagation path in one sector of an arbitrary set of sectors and a propagation path in another sector are estimated. The code sequences used for the above are orthogonal to each other, and each code sequence is generated so that some of the components of each code sequence are orthogonal to each other, and data of a single system using single or multiple antennas In the case of performing communication and in the case of performing data communication of a plurality of systems using a plurality of antennas, each generated code string is assigned to a subcarrier by the same method, and a symbol is assigned to a mobile station apparatus existing in each sector. Send. [Selection] Figure 9

Description

  The present invention relates to a radio communication method and a receiver capable of performing propagation path estimation with high accuracy in an OFDM communication system and suppressing the influence on other sectors when using MIMO.

  Conventionally, a communication system using OFDM (Orthogonal Frequency Division Multiplexing), in which each base station uses the same frequency band, each base station has several sectors, and all the sectors are similarly the same. Communication systems that use frequency bands are known. In such a communication system, since the same base station controls between sectors, it is considered that communication from the base station to the mobile station is synchronized in all sectors. Therefore, a propagation path estimation symbol (CE symbol: Channel Estimate), which is necessary for OFDM, is transmitted at the same timing. Therefore, the mobile station can not only estimate the propagation path, but also this symbol. It is considered desirable to be able to identify from which sector the symbol is transmitted and to measure which sector has high accuracy of radio waves.

  FIG. 16 shows codes used for propagation path estimation symbols when the number of sectors controlled by the base station is three. In FIG. 16, it is assumed that one square is a code of each subcarrier. It indicates that "1" is input to "1 + 0j" and "-1" is input to "-1 + 0j" in the complex IFFT (Inverse Fourier Transform) input in the OFDM transmitter to create a symbol for propagation path estimation. .

  The pattern shown in FIG. 16 has a configuration in which a code string composed of four codes is repeatedly assigned to subcarriers for each sector. That is, (1, 1, 1, 1) in sector 1, (1, -1, -1, 1) in sector 2, (1, 1, -1, -1) in sector 3, Is an orthogonal code (multiply each code word and add up to 0).

  FIG. 17 shows a block configuration of a receiver capable of identifying this code and estimating a propagation path with a sector to be connected. FIG. 18 is a block diagram showing a detailed configuration of the correlation calculation unit of FIG. A basic propagation path estimation method will be described with reference to FIGS. 17 and 18. In FIG. 17, the received OFDM signal is symbol-synchronized, and the data of the number of points necessary for FFT from the OFDM symbol is input to an FFT unit (Fast Fourier Transform) 101 and subjected to FFT. The FFTed data is input to the correlation calculation units 102_1 to 102_3 when the symbol is CE. Here, the reason why there are three correlation calculation units is that the system assumed here is three sectors, and therefore it is necessary to identify three types of signals.

  In each of the correlation calculation units 102_1 to 102_3, correlation detection is performed based on the pattern of each sector. Details will be described with reference to FIG. During the output of the FFT unit 101, data corresponding to the number of subcarriers is input. Since the codes for identifying the sectors are four orthogonal codes, the correlation is calculated every four subcarriers. Here, assuming that the total number of subcarriers used for transmission is 4N, N correlation units 150_1 to 150_3 (portions surrounded by squares in FIG. 18) are required for one correlation calculation unit.

  One correlator receives f4k-3, f4k-2, f4k-1, and f4k (k is a natural number from 1 to N) during FFT output. Here, fx represents the FFT output of the xth carrier as a complex number, and in the case of f4k-3, it is the output of the 4k-3th subcarrier. In this grouping, four subcarriers assigned so as to form an orthogonal system are selected. These data are multiplied by the complex conjugate signals of the codes used in the transmission system in the multipliers 121_1 to 121_4. Here, the Sector code 1 is stored in the memory 120_1, the Sector code 2 is stored in the memory 120_2, the Sector code 3 is stored in the memory 120_3, and the Sector code 4 is stored in the memory 120_4.

  For example, when the correlation of sector 1 is detected, all 1s are set from 120_1 to 120_4, and in the case of sector 2, 1 is set to 120_1 and 120_4, and -1 is set to 120_2 and 120_3. These are added by the sum calculation unit 122. This signal is assumed to be Fm (Fm is a complex number, m is a natural number from 1 to N), and Fm is output to the selector 103, while the absolute value calculator 123 calculates the absolute value of Fm. Thereafter, the sum calculation unit 124 adds all m and outputs the result to the sector selection unit 104.

  When the received OFDM signal is from only one base station, only one of the data 102_1 to 102_3 output to the sector selection unit 104 has a large value, and the other has a small value. This is because the codes are orthogonal, and this relationship is maintained as long as the propagation path does not vary greatly within the four subcarriers.

  Therefore, the sector selection unit 104 determines the data of the correlation calculation units 102_1 to 102_3 that has the maximum output as the transmission sector, and selects the Fm obtained by the correlation calculation unit corresponding to the selected sector to the propagation path estimation unit 105. Input via the unit 103.

  The propagation path estimation unit 105 estimates the propagation path of each subcarrier based on the input Fm. Here, since the propagation path fluctuations in the four subcarriers used for calculating Fm are constant as described above, the propagation path from f4m-3 to f4m is estimated as Fm / 4. The

Data is demodulated based on the propagation path information thus obtained. The data OFDM symbol input to the FFT unit 101 is subjected to FFT and input to the propagation path compensation unit 106. The propagation path compensation unit 106 compensates the propagation path for each subcarrier by multiplying the complex conjugate signal of the propagation path estimation value obtained previously. Then, the data subjected to propagation path compensation is input to the data demodulation unit 107, and the transmission data is demodulated.
Special Table 2006-200684 gazette “3GPP R1-050589 NTT DoCoMo”

  However, in recent communication systems, it is indispensable to introduce MIMO (Multi-Input Multi-Output) to improve system throughput. FIG. 19 shows a preamble pattern in the case of assuming 2 × 2 MIMO (two series of data are transmitted simultaneously from transmission and processed by the reception system of the system on the reception side). In FIG. 19, white squares are transmitted only from the antenna 1, and shaded squares are transmitted only from the antenna 2. As shown in FIG. 19, if a preamble is set, orthogonality can be maintained between sectors for each antenna, and propagation path estimation can be performed at intervals of 8 subcarriers.

  However, the pattern in this example differs from the pattern shown in FIG. 16 for each subcarrier, so that all mobile terminals can receive MIMO, and transmission using MIMO is performed in advance by some means. It is necessary to be aware of what is being done. Terminals that cannot receive MIMO should not be ignored from the viewpoint of low power consumption in the actual system, and it is desirable that the system operates normally even if such terminals exist.

  The present invention has been made in view of such circumstances. In the OFDM communication system, it is possible to estimate a propagation path with high accuracy even near the edge of a sector and to perform MIMO reception. An object of the present invention is to provide a wireless communication method for generating and transmitting a preamble pattern that does not deteriorate the communication performance of the entire system even if a terminal is present, and a receiver for receiving the preamble pattern.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the radio communication method according to the present invention is a radio communication method of a base station apparatus that controls a plurality of sectors and performs radio communication with a mobile station apparatus existing in any sector by an OFDM communication scheme. In addition, a code string used for estimating a propagation path in one sector of an arbitrary set of sectors and a code string used for estimating a propagation path in the other sector are orthogonal to each other. The code sequences are generated so that some of the components of the code sequences are orthogonal to each other, and a single system data communication is performed using a single antenna or a plurality of antennas, and a plurality of antennas are used. When performing data communication of a plurality of systems, the generated code strings are allocated to subcarriers by the same method, and symbols are transmitted to mobile station apparatuses existing in each sector. It is.

  In this way, a code string used to estimate a propagation path in one sector of an arbitrary set of sectors controlled by the base station apparatus and used to estimate a propagation path in the other sector Not only is the code sequence orthogonal to each other, but also part of each code sequence component is orthogonal to each other, making it less susceptible to frequency fluctuations due to fading than in the past, and maintaining and improving the estimation accuracy of the propagation path Is possible. Further, by using such a code, it is possible to easily determine whether the reception side is MIMO or SISO by detecting the correlation.

  (2) In addition, the wireless communication method according to the present invention can use MIMO for performing data communication of a system whose maximum number of antennas is M or less (M is a natural number) and controls a plurality of sectors. Is a wireless communication method of a base station apparatus that performs wireless communication with a mobile station apparatus existing in a sector of the same by an OFDM communication method, and estimates a propagation path in any one of the sectors The code sequence Ca used for the purpose is expressed as Ca = (A1, A2,..., An) (n is a natural number indicating the code length), and the code sequence used for estimating the propagation path in the other sector When Cb is expressed as Cb = (B1, B2,..., Bn) (n is a natural number and represents a code length), (A1, A2,..., An) and (B1, B2,... ., Bn) are orthogonal to each other, and R and k are ≦ R ≦ M, 0 ≦ k <n / M, an integer satisfying a part of the code string Ca is expressed as (AR,..., A (k × M + R),. When a part of the components of the code string Cb is expressed as (BR,..., B (k × M + R),...), (AR,..., A (k × M + R),. ) And (BR,..., B (k × M + R),...) Are orthogonally generated, and m (m is a divisor of M) system MIMO is used. When the subcarrier number for channel estimation is k, the code strings Ca and Cb are used for each subcarrier for channel estimation classified by (k mod M) mod m and the subcarrier for channel estimation. It is characterized by transmitting symbols from the same antenna by assigning to numbers.

  In this way, a code string used to estimate a propagation path in one sector of an arbitrary set of sectors controlled by the base station apparatus and used to estimate a propagation path in the other sector Not only is the code sequence orthogonal to each other, but also part of each code sequence component is orthogonal to each other, making it less susceptible to frequency fluctuations due to fading than in the past, and maintaining and improving the estimation accuracy of the propagation path Is possible. Further, by using such a code, it is possible to easily determine whether the reception side is MIMO or SISO by detecting the correlation.

  (3) Also, in the wireless communication method according to the present invention, a combination of code sequences is repeatedly assigned N / n times to the number N of subcarriers for propagation path estimation (N is a natural number), and symbols are transmitted from the same antenna. It is characterized by transmitting.

  This configuration makes it less susceptible to frequency fluctuations due to fading than before, and can maintain and improve the estimation accuracy of the propagation path. Further, by using such a code, it is possible to easily determine whether the reception side is MIMO or SISO by detecting the correlation.

  (4) Also, in the radio communication method according to the present invention, a combination of different code sequences is assigned to the number N of subcarriers for propagation path estimation (N is a natural number), and symbols are transmitted from the same antenna. It is characterized by.

  This configuration makes it less susceptible to frequency fluctuations due to fading than before, and can maintain and improve the estimation accuracy of the propagation path. Further, by using such a code, it is possible to easily determine whether the reception side is MIMO or SISO by detecting the correlation.

  (5) In addition, the radio communication method according to the present invention is characterized in that symbols are assigned to different combinations of antennas and transmitted to a mobile station apparatus existing in each sector a plurality of times.

  In this way, since symbols are transmitted multiple times within one packet, the code string can be expanded in the time direction, and the propagation path estimation system can be maintained and improved even if a large frequency fluctuation occurs in the subcarrier interval. Is possible.

  (6) Further, in the wireless communication method according to the present invention, n is a natural number and represents the code length of the code strings Ca and Cb, and between the divided code strings obtained by dividing the code strings Ca and Cb into M, (A1,..., A (n / M)) and (B1,..., B (n / M)) are orthogonal, and (A (n / M) +1,..., A (2n / M)) and (B (n / M) +1,..., B (2n / M)) are orthogonal,..., (A ((M−1) × n / M + 1),. .., A (n)) and (B ((M−1) × n / M + 1),..., B (n)) are generated to generate code sequences Ca and Cb satisfying all the relationships. It is characterized by that.

  As described above, since the orthogonal relationship is established for all the components between the code strings Ca and Cb, and the M consecutive components are also established as the orthogonal relationship, the average channel characteristic is estimated in the continuous subcarriers. Is possible. Furthermore, it becomes difficult to be affected by propagation path fluctuations in the frequency direction, and the propagation path estimation system can be improved.

  (7) The wireless communication method according to the present invention is characterized in that any two sectors are adjacent sectors.

  This configuration makes it less susceptible to frequency fluctuations due to fading than before, and can maintain and improve the estimation accuracy of the propagation path. Further, by using such a code, it is possible to easily determine whether the reception side is MIMO or SISO by detecting the correlation.

  (8) In addition, in the wireless communication method according to the present invention, code sequences used to control three sectors adjacent to each other and estimate a propagation path in each sector are respectively (1, 1, 1, 1,1,1,1,1,), (1,1, -1, -1, -1, -1, -1,1,1,) and (1, -1, -1, -1, -1, 1, -1, 1).

  In this way, an orthogonal relationship is established for all the components of each code string, and an orthogonal relationship is also established between four consecutive components, so that it is possible to estimate the average propagation path characteristics in consecutive subcarriers. Become. Furthermore, it becomes difficult to be affected by propagation path fluctuations in the frequency direction, and the propagation path estimation system can be improved.

  (9) Further, in the case of performing MIMO communication, the radio communication method according to the present invention exists at both ends of a single data subcarrier when a code sequence for propagation path estimation and data are arranged in subcarriers. One of the propagation path estimation subcarriers and the single data subcarrier transmitted from the same antenna, or propagation path estimation existing at both ends of a plurality of continuous data subcarrier groups Any one of the data subcarriers and the plurality of continuous data subcarrier groups are transmitted from the same antenna.

  In this way, either one of the propagation path estimation subcarriers existing at both ends of a single data subcarrier and the single data subcarrier are transmitted from the same antenna or are continuous. Since either one of the subcarriers for channel estimation existing at both ends of the plurality of data subcarrier groups and the plurality of continuous data subcarrier groups are transmitted from the same antenna, the communication partner is only SISO. Even in a communication device that supports the above, it is possible to demodulate data at the communication partner. For example, by including information indicating that the transmission is based on “MIMO” in the data portion, a communication apparatus that supports only SISO can recognize that the transmission is from the first received slot. Since the subsequent slots can stop the demodulation operation, it is possible to save the power of the communication apparatus that supports only SISO.

  (10) A receiver according to the present invention is a receiver that receives data transmitted by the OFDM communication method, calculates a complex information of each subcarrier by performing fast Fourier transform on the received symbol, In the case of the maximum number of antennas in the range of the FFT unit that divides and outputs complex information for each carrier into subcarrier groups to which code sequences are assigned, and one code sequence length assigned to subcarriers for channel estimation A determination unit that performs correlation calculation for each set of subcarriers transmitted by different antennas using a corresponding code string, and performs MIMO transmission determination using autocorrelation and cross-correlation of the correlation calculation result for the set; It is characterized by providing.

  In this way, in the range of one code string length allocated to the subcarriers for channel estimation, for each subcarrier set transmitted with different antennas in the case of the maximum number of antennas, a correlation calculation is performed using a corresponding code string. Since the MIMO transmission is determined using the auto-correlation and cross-correlation of the correlation calculation result for the above set, the propagation path is estimated without being affected by the adjacent sector without impairing the orthogonality. Can be performed. Also, it is possible to easily determine whether it is MIMO or SISO.

  (11) In the receiver according to the present invention, the determination unit integrates the autocorrelation value and the cross-correlation value of the correlation calculation result performed for each set in the range of one code length in a plurality of code length ranges. It is characterized by doing.

  In this way, since the autocorrelation value and the cross-correlation value of the correlation calculation result performed for each set in the range of one code length are integrated in a plurality of code length ranges, it is possible to detect from adjacent sectors without impairing the orthogonality. The propagation path can be estimated without being affected by the above. Also, it is possible to easily determine whether it is MIMO or SISO.

  (12) In the receiver according to the present invention, the determination unit sets a range of a plurality of code lengths to be integrated as a range of the minimum number of subcarriers allocated to the receiver.

  In this way, since the range of multiple code lengths to be integrated is the range of the minimum number of subcarriers that can be allocated to the receiver, propagation path estimation is performed without affecting the orthogonality and without being affected by adjacent sectors. Can be performed. Also, it is possible to easily determine whether it is MIMO or SISO.

  (13) Further, in the receiver according to the present invention, the determination unit is characterized in that a range of a plurality of code lengths to be integrated is the entire communication band.

  In this way, since the range of a plurality of code lengths to be integrated is the entire communication band, it is possible to estimate the propagation path without being affected by adjacent sectors without impairing the orthogonality.

  (14) Further, the receiver according to the present invention is characterized in that MIMO transmission is also determined for adjacent sectors, and the correlation calculation method for the code string is changed.

  In this way, MIMO transmission is also determined for the adjacent sector and the correlation calculation method for the code string is changed, so that the propagation path is estimated without being affected by the adjacent sector without impairing the orthogonality. It becomes possible.

  (15) In addition, a mobile station apparatus according to the present invention includes the receiver according to any one of claims 10 to 14.

  According to the mobile station apparatus according to the present invention, for each set of subcarriers transmitted by different antennas in the case of the maximum number of antennas, in the range of one code string length allocated to subcarriers for channel estimation, Correlation calculation is performed using the corresponding code string, and MIMO transmission is determined using the autocorrelation and cross-correlation of the correlation calculation result for the above set, so that it is affected by adjacent sectors without impairing orthogonality. Therefore, it is possible to estimate the propagation path. Also, it is possible to easily determine whether it is MIMO or SISO.

  (16) Further, the base station apparatus according to the present invention controls a plurality of sectors, and performs base station radio communication with the mobile station apparatus according to claim 14 existing in any sector by the OFDM communication method. A station apparatus, a code string used for estimating a propagation path in one sector of any one set of adjacent sectors, and a code string used for estimating a propagation path in the other sector; Are orthogonal to each other, and a code string generation unit that generates the code strings so that a part of the components of the code strings are orthogonal to each other, and assigns the generated code strings to subcarriers, And a transmitter that transmits a symbol to the mobile station apparatus according to claim 15.

  According to the base station apparatus according to the present invention, a code string used for estimating a propagation path in one sector of any pair of adjacent sectors and a propagation path in the other sector are estimated. Not only are the code strings used orthogonal to each other, but also some of the components of each code string are orthogonal to each other, making it less susceptible to frequency fluctuations due to fading and maintaining and improving propagation path estimation accuracy. It becomes possible to make it.

  (17) Moreover, according to the radio | wireless communications system which concerns on this invention, it is comprised from the mobile station apparatus of Claim 15, and the base station apparatus of Claim 16. It is characterized by the above-mentioned.

  The radio communication system according to the present invention makes it less susceptible to frequency fluctuations due to fading than before, and can maintain and improve propagation path estimation accuracy.

  According to the present invention, a code string used for estimating a propagation path in one sector of a set of sectors controlled by the base station apparatus, and used for estimating a propagation path in the other sector. Not only is the code sequence orthogonal to each other, but also part of each code sequence component is orthogonal to each other, making it less susceptible to frequency fluctuations due to fading than in the past, and maintaining and improving the estimation accuracy of the propagation path Is possible. Further, in the case of performing single-system data communication using a single or a plurality of antennas and in the case of performing data communication of a plurality of systems using a plurality of antennas, the generated code strings are sub-subjected by the same method. By allocating to a carrier and transmitting a symbol to a mobile station apparatus existing in each sector, it is possible to eliminate the influence on the system even if there is a terminal that can handle only single data communication. In addition, by using such a code and detecting the correlation on the receiving side, it is possible to easily determine whether it is MIMO or SISO.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a radio communication system according to the present embodiment. This wireless communication system includes a base station apparatus 1 (sometimes simply referred to as “base station”) and a mobile station apparatus 2 (sometimes simply referred to as “mobile station”). The base station apparatus 1 transmits, to the mobile station apparatus 2, a code string (sometimes referred to as a preamble pattern in this specification) for estimating the propagation path generated by the code string generation unit 1 b by the transmission unit 1 a. . The mobile station apparatus 2 measures or estimates the propagation path state based on the received code string, and transmits the measured or estimated result to the base station apparatus 1. The base station apparatus 1 receives the information indicating the propagation path state transmitted from the mobile station apparatus 2 by the receiving unit 1c.

(First embodiment)
FIG. 2 shows an example of a preamble pattern in the present invention. However, 2 × 2 MIMO is considered in which the number of sectors controlled by the base station apparatus 1 is 3, and the maximum number of MIMO transmission sequences is 2. In FIG. 2, the upper diagram is a transmission pattern with a single antenna, and the lower diagram is a transmission pattern with a double antenna (during MIMO).

  First, the principle by which a propagation path between sectors can be identified by using an orthogonal code first will be briefly described.

  The symbols (1, 1, -1, -1) are repeated from sector A to CE in the subcarrier (frequency) direction, and from sector B, (1, -1, -1, 1) is the same. It is configured. This is a propagation path estimation symbol that can be used when the propagation path is considered to be constant at about 4 subcarriers.

  In a certain receiver, the propagation path from subcarriers k to k + 3 from sector A is uniformly fa−k, and similarly the propagation path from sector B is uniformly fb−k. After receiving the CE and synchronizing symbols, the FFT outputs from subcarriers k to k + 3 are fa−k × 1 + fb−k × 1, fa−k × 1 + fb−k × (−1), fa−k × (−1). ) + Fb−k × (−1), fa−k × (−1) + fb−k × 1. When obtaining the propagation path from the sector A, multiplying and adding (1, 1, -1, -1) to these results in 4 × fa-k. It is possible to calculate the propagation path from k to k + 3. Similarly, when obtaining the propagation path from sector B, fb−k can be calculated by multiplying (1, −1, −1, 1) and performing the same processing.

  The pattern shown in FIG. 2 uses an orthogonal code string composed of eight codes. Sector 1 (1,1,1,1,1,1,1,1), Sector 2 (1,1, -1, -1, -1, -1, -1,1, 1), Sector 3 ( 1,1,1,1, -1, -1, -1, -1). As shown in the above principle, a system is assumed in which the propagation path is considered to be almost constant between the eight subcarriers.

  The codes used in the first embodiment have eight code words orthogonal to each other, and codes composed of every other four code words are also orthogonal. That is, it is orthogonalized by subcarrier pairs of (1, 3, 5, 7), orthogonalized by subcarrier pairs of (2, 4, 6, 8), and (1, 2, 3, 4, 5, 6, 7 and 8) are sub-orthogonalized. This arrangement is repeated for all subcarriers.

  In the receiver on the mobile station apparatus 2 side, when detecting the correlation, it is assumed that the transmitting side is transmitting from two antennas and the correlation is taken every other subcarrier to detect which antenna is being used. There is a need. Therefore, the block configuration for receiving this preamble and demodulating the data is almost the same as the conventional example, and the input pattern to the correlation calculation unit is different.

  FIG. 3 shows a block configuration of the receiver 30 that can identify this code and can estimate the propagation path to the sector to be connected. However, the receiver 30 having the block configuration of FIG. 3 cannot perform MIMO reception.

  FIG. 4 is a diagram showing details of the correlation calculation units 102_2 to 102_3 in FIG. A basic propagation path estimation method is shown along FIGS. In FIG. 3, the received OFDM signal is symbol-synchronized, and data of the number of points necessary for FFT from the OFDM symbol is input to an FFT unit (Fast Fourier Transform) 101 and subjected to FFT. . The FFTed data is input to the correlation calculation units 102_1 to 102_3 when the symbol is CE. Here, the reason why there are three correlation calculation units is to identify three types of signals because the assumed system is three sectors. The reason why there are two correlation calculation units a and b is to explicitly indicate that odd-numbered subcarriers and even-numbered subcarriers are input to separate correlation calculation units.

  Correlation calculators 102_1 to 102_3 perform correlation detection based on the pattern of each sector. This will be described in detail with reference to FIG. During the output of the FFT unit 101, data for subcarriers is input. Since the code for identifying the sector is an orthogonal code of four code words using every other eight code words, the correlation is calculated every four subcarriers. Here, if the total number of subcarriers used for transmission is 8N, N correlation units 1s to Ns (portions surrounded by squares in FIG. 4) are required for one correlation calculation unit.

The correlation calculation units 102_1a to 102_3a indicated by the subscript “a” receive four sets of odd-numbered subcarriers during FFT output. The input subcarrier number is k as a natural number of N or less,
f {8 (k−1) +1},
f {8 (k-1) +3},
f {8 (k-1) +5},
f {8 (k−1) +7},
In the correlation calculation units 102_1b to 102_3b indicated by the subscript b,
f {8 (k-1) +2},
f {8 (k-1) +4},
f {8 (k-1) +6},
f {8 (k-1) +8} is input.

  fx represents the FFT output of the xth subcarrier in a complex number as in the conventional example, and f {8 (k−1) +1} is the {8 (k−1) +1} th subcarrier. FFT output.

  These data are multiplied by the complex conjugate signals of the codes used in the transmission system in the multipliers 121_1 to 121_4. Here, the Sector code 1 is stored in the memory 120_1, the Sector code 2 is stored in the memory 120_2, the Sector code 3 is stored in the memory 120_3, and the Sector code 4 is stored in the memory 120_4.

  For example, when the correlation of sector 1 is detected, all 1s are set from 120_1 to 120_4, and in the case of sector 2, 1 is set to 120_1 and 120_4, and -1 is set to 120_2 and 120_3. These are added by the sum calculation unit 122. The output from the correlation calculation unit (102_1a to 102_3a) whose subscript is a is Fm_a, the output from the correlation calculation unit (102_1b to 102_3b) whose subscript is b is Fm_b (m is a natural number from 1 to N), Fm_a , Fm_b is output to the selector 103, while the absolute value calculator 123 calculates the absolute values of Fm_a and Fm_b. Thereafter, the sum calculation unit 124 adds the correlation calculation units (102_1a to 102_3a) and the correlation calculation units (102_1b to 102_3b) and all m and outputs the result to the sector selection unit 104.

  When the received OFDM signal is from only one base station apparatus, only one of the data 102_1 to 102_3 output to the sector selection unit 104 has a large value, and the other has a small value. This is because the codes are orthogonal, and this relationship is maintained unless the propagation path fluctuates greatly within the eight subcarrier bands.

  Therefore, the sector selection unit 104 determines any one of the data in the correlation calculation units 102_1 to 102_3, which has the maximum output, as a transmission sector, and uses Fm_a and Fm_b obtained by the correlation calculation unit corresponding to the selected sector as MIMO. The data is input to the determination unit 108 via the selection unit 103. Normally, this sector selection is performed at the start of communication and is fixed during communication. However, in sector handover, sectors to be connected are selected by similar processing.

  Based on the input Fm, MIMO determination section 108 determines whether or not the transmitted channel estimation signal uses MIMO.

  Sm = | Fm_a × Fm_a * −Fm_a × Fm_b * | is calculated for a certain m. Here, * indicates a complex conjugate, and | x | indicates the absolute value of x.

  When the transmitting side is transmitting signals using the same antenna, Fm_a * and Fm_b * shown in the above equation are almost the same, so Sm calculates a value close to 0. Since the value is different when MIMO is used, Sm does not become zero. Using this property, it is possible to determine whether or not MIMO transmission is performed at the time of transmission in units of subcarriers to which codes are assigned.

  Furthermore, in the case of a system that determines whether or not to perform MIMO transmission in units of subchannels, such as an OFDMA system, it is possible to make a highly accurate determination by summing S with m constituting the subchannel. Become.

  Of course, in a system that determines whether or not MIMO transmission is simultaneously performed in all subchannels, it is considered that the highest accuracy is obtained when Sm is summed with all m.

  When the MIMO determination unit 108 determines that MIMO is not used, the propagation path is estimated from Fm_a and Fm_b, and the following signals are demodulated.

  Since this receiver is assumed to be unable to perform MIMO reception, when the MIMO determination unit 108 determines that the transmission data is MIMO transmission, the quality measurement unit 500 stores the quality information of each frequency or each antenna. The information is acquired and notified to the base station using a separate transmission means. Although this quality measurement unit 500 is not explicitly described in the conventional example, the provision of the MIMO determination unit 108 as shown in the first embodiment makes it impossible to identify each antenna by the conventional communication method. On the other hand, it is possible with the communication method shown here, and it is possible to prevent system performance deterioration due to erroneous notification.

  FIG. 5 shows details of the MIMO determination unit 108. Reference numerals 550_1 to 550_N denote autocorrelation calculators that calculate Fm_a × Fm_a *. On the other hand, 551_1 to 551_N are cross-correlation calculation units, and Fm_a × Fm_b * is calculated. 552_1 to 552_N are difference / absolute value calculation units for calculating Sm for each m. A determination unit 553 performs the above-described addition and the like according to the system, and estimates the transmission method of each subcarrier. Based on the estimation result, propagation path estimation for each subcarrier is performed.

  In this way, by assigning a code having the same orthogonality to the OFDM symbol for channel estimation in the transmitter when MIMO is used and when it is not used, in a terminal that cannot receive MIMO, data is erroneously transmitted during MIMO transmission. Demodulation is eliminated, and the reception quality can be notified to the base station separately when MIMO is used and when it is not used, so that scheduling and adaptive modulation at the base station can operate normally.

  On the other hand, when it is determined that MIMO is not used, the propagation path estimation unit 105 estimates the propagation path of each subcarrier based on the input Fm. Here, as described above, since the propagation path fluctuations in the four subcarriers used for calculating Fm are constant, the propagation path of four subcarriers is arbitrary for any m. It is estimated as Fm_a / 4.

  Further, since the Fm_a and Fm_b propagation paths are considered to be substantially the same, the propagation path of 8 subcarriers for an arbitrary m can be set to (Fm_a + Fm_b) / 8.

  Data is demodulated based on the propagation path information thus obtained. The data OFDM symbol input to the FFT unit 101 is subjected to FFT and input to the propagation path compensation unit 106. The propagation path compensation unit 106 compensates the propagation path for each subcarrier by multiplying the complex conjugate signal of the propagation path estimation value obtained previously. Then, the data subjected to propagation path compensation is input to the data demodulation unit 107, and the transmission data is demodulated.

  As described above, even in a receiver having the same configuration as the conventional one, by changing the subcarrier number input to the correlation calculation units 102_1 to 102_3, the orthogonality is not impaired and is not affected by the adjacent sector. In addition, it is possible to estimate the propagation path, and it is possible to calculate the reception quality in units of transmission antennas even when MIMO is used on the transmission side, and scheduling or adaptive modulation in the base station works normally.

  Next, an example of a receiver considering MIMO is shown in FIG. As in the previous example, the MIMO determination unit 108 determines whether or not the packet or frame uses the MIMO from the transmitted preamble. In addition to this configuration, a method for notifying that the communication is based on MIMO in advance, or a data area where a part of data can be demodulated even during normal reception is set, and the following data in that area is MIMO. A method of notifying the user can also be considered.

  In FIG. 6, blocks having the same functions as those in FIG. Therefore, the difference from FIG. 3 is that the propagation path compensation unit 109 and the data demodulation unit 110 are configured to support MIMO, and that there are two systems because the reception system is MIMO. This receiving system has the same configuration for both 1 and 2.

  Most of the operations are the same as the previous example, but the difference is the operation after determining that MIMO transmission is being performed on the transmission side.

  When it is determined that the transmission is MIMO transmission, propagation path estimation section 105 estimates the propagation path for each antenna and each subcarrier. The operation is almost the same as in the previous example, but since it is MIMO transmission, no addition processing is performed. Therefore, for any m, the propagation path information of every 8 subcarriers uses Fm_a / 4 for antenna 1 and Fm_b / 4 for antenna 2.

  In this way, even when receiving MIMO, data can be demodulated, and by setting the preamble as shown in FIG. 2, orthogonality between sectors is maintained, so what kind of communication is performed in adjacent sectors during MIMO. Therefore, it is possible to estimate the propagation path with high accuracy without being limited to whether it is present.

  By realizing the preamble configuration and the receiver configuration as described so far, it is possible to realize MIMO reception without deterioration of characteristics while enabling sector identification. In the first embodiment, the configuration of the preamble and its receiver assuming two transmission systems of MIMO has been described. However, even the M system can be realized with the same configuration. FIG. 7 shows two types of preambles assuming the case of four systems, suggesting expansion to M systems.

  The upper diagram in FIG. 7 is an extension of the preamble pattern in the frequency axis direction. The white rectangle is the antenna 1, the rectangle with the diagonally left-down line is the antenna 2, and the rectangle with the diagonally-downward line is The antenna 3 is a shaded rectangle. By setting the orthogonal code repetition interval to M in this way, the same orthogonal code is used to form a preamble pattern that can accurately estimate the propagation path in both normal OFDM and MIMO while maintaining orthogonality between sectors. can do.

  However, in the above example, there is a problem that large frequency fluctuations in 16 bands are not allowed at subcarrier intervals. Corresponding to this is the lower diagram of FIG. This is a concept that extends in the time direction. In this case, by preparing preamble symbols, for example, “the smallest integer equal to or greater than (M / 2)”, the propagation paths of all antennas can be estimated.

  In any of the examples, the subcarrier in the CE symbol is known, but it is also possible to insert a data subcarrier in between.

  FIG. 8 shows a preamble pattern in the case where data is arranged also in the CE symbol in consideration of 2 × 2 MIMO. In FIG. 8, what is indicated by “D” is the data portion. In the case of this configuration, after estimating the propagation path, it is necessary to demodulate the D-carrier subcarrier. In FIG. 8, D is sequentially transmitted to antenna 1 and antenna 2 as well, but with this configuration, even a terminal that cannot demodulate MIMO can demodulate only this part, and control data can be transmitted to this part. By storing, efficient communication becomes possible.

(Second Embodiment)
FIG. 9 shows an example of a preamble pattern in the second embodiment of the present invention. As in the first embodiment, 2 × 2 MIMO is considered in which the number of sectors controlled by the base station apparatus 1 is 3, and the maximum number of MIMO transmission sequences is 2.

  In FIG. 9, the upper diagram is a transmission pattern with a single antenna, and the lower diagram is a transmission pattern with a double antenna (during MIMO). Similar to the preamble pattern shown in the first embodiment, the bit pattern is the same for the single antenna and the double antenna. Further, the pattern shown in FIG. 9 uses a code string composed of four codes as in the first embodiment.

  Also in the second embodiment, orthogonal codes are arranged every other subcarrier, and at the time of MIMO transmission, a preamble pattern is transmitted from a different antenna for each subcarrier. As in the first embodiment, in the receiver, as shown in FIG. 10, in order to detect the optimum sector for transmitting and receiving wireless data at the start of wireless communication, the respective correlation calculation units 102_1 and 102_2 corresponding to the three sectors are detected. , 102_3, the correlation value is calculated. When calculating the correlation, the subcarrier selecting unit 501 selects four subcarriers every other subcarrier, and a correlation calculating unit in which the number corresponding to 2 which is the maximum transmission sequence in the second embodiment is set. At 102, a correlation value is calculated. Since the essential part of the correlation value calculation method is the same as that of the first embodiment, a description thereof will be omitted.

  In the second embodiment, one of the differences from the first embodiment is that the MIMO determination unit 108 shown in FIG. 10 is provided in a number corresponding to each sector, and the sector selection unit 104 performs wireless operations for the operation. This is to determine not only the sector determined to perform communication but also the transmission format of the adjacent sector. Since the method for determining each sector is the same as that of the first embodiment, a description thereof will be omitted. Based on this determination result, it can be used as an index for switching the subcarrier combination of the preamble pattern input to the correlation calculation section described later.

FIG. 11 shows details of the correlation calculation unit according to the second embodiment. In the second embodiment, as described above, the number of correlation calculation units corresponding to 2 of the maximum transmission sequence is provided in the same number as the number of sectors as in the first embodiment. An example is shown. The difference from the first embodiment is that the arrangement pattern of orthogonal codes is different. That is, the subcarrier position input to the multiplication unit in FIG. 11 is different, specifically, the fx values input to the multiplication units 121_1 to 121_4 are respectively
f {8k-7},
f {8k-5},
f {8k-3},
f {8k-1}. Here, k is a natural number from 1 to N.

Further, the fx values of the other correlation calculation unit for corresponding to the maximum number of transmission sequences of 2 in the second embodiment are respectively
f {8k},
f {8k-2},
f {8k-4},
f {8k-6}. Here again, k is a natural number from 1 to N.

  11, the first, ninth, 17, 25th, etc. subcarriers are input to the multiplier 121_1, and the third, eleventh, 19, 27th, etc. subcarriers are input to the multiplier 121_2. Similarly, the fifth, 13, 21, 29,. Also in the second embodiment, similarly to the first embodiment, after the sector selection unit 104 selects a sector, propagation path estimation for each subcarrier of the selected sector is performed. The propagation path estimation method in FIG. 11 is the same as that in the first embodiment described above, and a description thereof will be omitted.

  Data is demodulated based on the propagation path information obtained as described above. The data OFDM symbol input to the FFT unit 101 is subjected to FFT and input to the propagation path compensation unit 106. The propagation path compensation unit 106 compensates the propagation path for each subcarrier by multiplying the complex conjugate signal of the propagation path estimation value obtained previously. Then, the data subjected to propagation path compensation is input to the data demodulation unit 107, and the transmission data is demodulated.

  Thus, even in a receiver having the same configuration as the conventional one, by changing the subcarrier number input to the correlation calculation unit, the orthogonality is not impaired, and the propagation path is not affected by the adjacent sector. It becomes possible to estimate.

  Furthermore, there are the following features as advantages in the second embodiment. The preamble pattern shown in the lower diagram of FIG. 2 is a 2 × 2 MIMO communication scheme pattern set to be transmitted from a different antenna every other subcarrier and a preamble pattern (upper side) using one transmission antenna. This figure is characterized in that the arrangement pattern of the orthogonal codes of the preamble pattern using the same pattern is the same, but since four codes are arranged every other subcarrier, the average of 8 subcarriers The propagation path characteristics were estimated.

  However, in the second embodiment, since the preamble pattern shown in FIG. 9 is used, the code patterns of four consecutive subcarriers are orthogonal during wireless communication using one transmission antenna. It becomes possible to estimate the average propagation path characteristic of the carrier. That is, the preamble pattern is more resistant to propagation path fluctuations in the frequency axis direction than the preamble pattern in the first embodiment, and it is possible to perform more accurate propagation path estimation.

  Further, a communication method in which whether the data to be transmitted is MIMO transmission data or SISO transmission data is not notified in advance or a mobile station that has not been able to receive advance notification information uses SINR, SIR, SNR, reception using a preamble symbol. When measuring the propagation path environment typified by electric power, etc., it becomes possible to perform accurate measurement regardless of MIMO and SISO communication systems by using preamble symbols arranged every other subcarrier. In addition, the measurement data can be fed back to the base station.

  Whether the subcarrier combination to be input to the preamble pattern correlation calculation unit in the second embodiment is switched by the MIMO determination unit 108 by MIMO or SISO using the same method as in the first embodiment. to decide. At this time, the transmission format used in the adjacent sector, that is, whether it is MIMO or SISO is determined in a similar manner, and the interference level of the adjacent cell is determined based on the signal strength from each sector.

  Next, when it is determined in the above determination that wireless communication by SISO is being performed, a combination of preamble symbol patterns for performing propagation path estimation is selected according to the following indices. As a result, more accurate propagation path estimation can be performed, and wireless communication resistant to propagation path fluctuation can be performed.

Specifically, the combination of the subcarriers in the preamble pattern of the sector that is currently communicating is switched from the above combination to the combination of four adjacent subcarriers represented by the following formula.
f {8k-7},
f {8k-6},
f {8k-5},
f {8k-4}
Furthermore, the combination input to the other correlation calculation unit is
f {8k-3},
f {8k-2},
f {8k-1},
f {8k}.
Here, k is a natural number from 1 to N. These correspond to the multiplication unit 121_1, the multiplication unit 121_2, the multiplication unit 121_3, and the multiplication unit 121_4 from the top.

  Further, regarding the switching index, it is desirable to perform switching according to the state of propagation path fluctuation, and switching is performed so that propagation path fluctuations in the four subcarrier sections for which propagation path estimation is performed are constant. Methods for evaluating propagation path fluctuation include methods such as measuring delayed waves, measuring the moving speed of mobile stations, or statistically judging from temporal fluctuations in subcarrier reception intensity, and combinations of these. A method of judging can be considered. Furthermore, wireless communication with a better propagation path environment can be performed by determining the transmission power level of the adjacent sector together with the interference power level by the above means.

  That is, it is desirable to consider whether the adjacent sector is performing SISO communication or MIMO communication, and the influence of the interference power level. It is also possible to perform a method of notifying the mobile station of the switching instruction as information from the base station in the control information in the received data without determining the switching index by the mobile station. In this case, after demodulating the control information in the received data, switching between the method for performing channel estimation again and the channel estimation method before demodulating the traffic data section and notifying the base station before receiving the demodulated data A method is conceivable.

  Note that the propagation path estimation method and the MIMO receiver configuration when using MIMO are the same as those in the first embodiment described above, and a description thereof will be omitted.

  Next, FIG. 12 shows two types of preambles assuming a case where there are four transmission sequences, suggesting expansion to M systems. The upper diagram in FIG. 12 is an extension of the preamble pattern in the frequency axis direction. The white rectangle is the antenna 1, the rectangle with the diagonally left-down line is the antenna 2, and the rectangle with the diagonally-downward line is The antenna 3 is a shaded rectangle. By setting the orthogonal code repetition interval to M in this way, the same orthogonal code is used to form a preamble pattern that can accurately estimate the propagation path in both normal OFDM and MIMO while maintaining orthogonality between sectors. can do.

  Further, the second embodiment is characterized in that the codes of four subcarriers continuous in the frequency direction are orthogonal between sectors as in the above-described 2 × 2 MIMO transmission / reception.

  On the other hand, the lower side of FIG. 12 corresponds to the lower side of FIG. 7 in the first embodiment. This is a concept that extends in the time direction in the same manner as in the first embodiment. For example, by preparing preamble symbols such as “the smallest integer equal to or greater than (M / 2)”, the propagation paths of all antennas are estimated. Is possible. In any of the embodiments, the subcarriers in the CE symbol are known, but it is possible to insert data subcarriers in between.

(Third embodiment)
FIG. 13 shows an example of a preamble pattern in the third embodiment of the present invention. As in the first embodiment, 2 × 2 MIMO is assumed in which the number of sectors controlled by the base station apparatus 1 is 3, and the maximum number of MIMO transmission sequences is 2. In FIG. 13, the upper diagram is a transmission pattern with a single antenna, and the lower diagram is a transmission pattern with a double antenna (during MIMO).

  The difference from the first embodiment is that a preamble pattern at the time of single antenna transmission is arranged for each subcarrier, and symbols between the preamble symbols are set as data symbol symbols. In the data symbol, a symbol of normal traffic data or control information data can be arranged.

  By arranging as described above, the number of preamble symbols for each antenna during single antenna transmission and double antenna transmission can be set to the same number. That is, at the time of single antenna transmission, half the number of preamble symbols is arranged compared to the case of double antenna transmission. Similarly to the first embodiment, a mobile station that performs reception using only a single antenna performs propagation path estimation by detecting a subcarrier preamble pattern similar to that used when performing single antenna transmission. It is possible.

  The pattern shown in FIG. 13 uses a code string composed of four codes as in the first embodiment. Also in the third embodiment, orthogonal codes are arranged every other subcarrier, and similarly to the first embodiment, when detecting the correlation, the receiver takes the correlation every other subcarrier and determines which antenna is used. Detect if it is being used.

  However, as in the first embodiment and the second embodiment, it is determined whether SISO or MIMO is obtained by correlating four preamble symbols arranged every other subcarrier in two sets of eight subcarriers. Therefore, it is desirable to notify the transmission method (SISO or MIMO) of the traffic data part by the control information transmitted by SISO.

In the third embodiment, since the essence of the propagation path estimation method is performed by the same method as that of the first embodiment, detailed description of the reception block diagram is omitted. FIG. 14 shows details of the correlation calculation unit in the third embodiment. As described above, in the third embodiment, the difference from the first embodiment is that the arrangement pattern of orthogonal codes is different, and therefore the subcarrier position input to the multiplication unit in FIG. 14 is different. Specifically, the fx values input to the multipliers 121_1 to 121_4 are respectively
f {8k-7},
f {8k-5},
f {8k-3},
f {8k-1}.
Here, k is a natural number from 1 to N. 14, the first, ninth, 17, 25th, etc. subcarriers are input to the multiplication unit 121_1, and the third, eleventh, 19, 27th, etc. subcarriers are input to the multiplication unit 121_2. Similarly, the fifth, thirteenth, twenty-first, thirty-second, etc. subcarriers are input to the multiplication unit 121_3, and the seventh, fifteenth, twenty-third, thirty-first, etc. subcarriers are input to the multiplication unit 121_4. The propagation path estimation method in FIG. 14 is the same as that in the first embodiment described above, and a description thereof will be omitted.

  Further, as the preamble pattern when using 4 × 4 MIMO, as shown in FIG. 15, it is possible to apply the same pattern as the lower diagram of FIG. In this case, as shown in FIG. 15, the preamble pattern of antenna 1 and antenna 2 is arranged at every 1 subcarrier for the first symbol, and the preamble pattern of antenna 3 and antenna 4 is similarly set at every other subcarrier for the following symbols. To place. However, the symbols on which the preamble patterns of the antennas 3 and 4 are arranged do not necessarily have to be a symbol that is continuous with the first symbol, that is, the second symbol.

  Data is demodulated based on the propagation path information obtained as described above. The data OFDM symbol input to the FFT unit 101 is subjected to FFT and input to the propagation path compensation unit 106. The propagation path compensation unit 106 compensates the propagation path for each subcarrier by multiplying the complex conjugate signal of the propagation path estimation value obtained previously. Then, the data subjected to propagation path compensation is input to the data demodulation unit 107, and the transmission data is demodulated.

  Thus, even in a receiver having the same configuration as the conventional one, by changing the subcarrier number input to the correlation calculation unit, the orthogonality is not impaired, and the propagation path is not affected by the adjacent sector. It becomes possible to estimate.

  Since the propagation path estimation method and the MIMO receiver configuration when using MIMO are the same as those in the first embodiment, the description thereof will be omitted.

It is a block diagram which shows schematic structure of a radio | wireless communications system. It is a figure which shows the preamble pattern which concerns on 1st Embodiment. It is a figure which shows the structure of the receiver which concerns on 1st Embodiment. It is a figure which shows the structure of the correlation calculating part of the receiver which concerns on 1st Embodiment. It is a figure which shows the detail of a MIMO determination part. It is a figure which shows the structure of the receiver which concerns on 1st Embodiment. It is a figure which shows the preamble pattern which concerns on 1st Embodiment. It is a figure which shows the preamble pattern which concerns on 1st Embodiment. It is a figure which shows the preamble pattern which concerns on 2nd Embodiment. It is a figure which shows the structure of the receiver which concerns on 2nd Embodiment. It is a figure which shows the structure of the correlation calculating part of the receiver which concerns on 2nd Embodiment. It is a figure which shows the preamble pattern which concerns on 2nd Embodiment. It is a figure which shows the preamble pattern which concerns on 3rd Embodiment. It is a figure which shows the structure of the correlation calculating part of the receiver which concerns on 3rd Embodiment. It is a figure which shows the preamble pattern which concerns on 3rd Embodiment. It is a figure which shows the preamble pattern used conventionally. It is a figure which shows the structure of the conventional receiver. It is a figure which shows the structure of the correlation calculating part of the conventional receiver. It is a figure which shows the preamble pattern used conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base station apparatus 2 Mobile station apparatus 1a Transmission part 1b Code sequence generation part 1c Reception part 30 Receiver 101 FFT part 102_1a-102_3b Correlation calculation part 103 Selection part 104 Sector selection part 105 Propagation path estimation part 106 Propagation path compensation part 107 Data Demodulation section 108 MIMO determination section 109 propagation path compensation section 110 data demodulation section 120_1 to 120_4 memory 121_1 to 121_4 multiplication section 122 sum calculation section 123 absolute value calculation section 124 sum calculation sections 550_1 to 550_N autocorrelation calculation sections 551_1 to 551_N cross correlation calculation Part

Claims (17)

A wireless communication method of a base station device that controls a plurality of sectors and performs wireless communication with a mobile station device existing in any sector by an OFDM communication method,
A code sequence used for estimating a propagation path in one sector of an arbitrary set of sectors and a code string used for estimating a propagation path in the other sector are orthogonal to each other, and Generating each code string such that some of the components of each code string are orthogonal to each other;
When performing single-system data communication using a single or multiple antennas and when performing multiple-system data communication using multiple antennas, the generated code strings are allocated to subcarriers by the same method. And transmitting a symbol to the mobile station apparatus existing in each sector. MIMO that performs data communication of a system whose maximum number of antennas is M or less (M is a natural number) can be used, controls a plurality of sectors, and performs OFDM with a mobile station apparatus existing in any sector A wireless communication method of a base station apparatus that performs wireless communication by a communication method,
Among all the sectors, a code string Ca used for estimating a propagation path in any one sector is:
Ca = (A1, A2,..., An) (n is a natural number and represents a code length),
The code sequence Cb used for estimating the propagation path in the other sector is:
When expressed as Cb = (B1, B2,..., Bn) (n is a natural number and represents a code length), (A1, A2,..., An) and (B1, B2,..., Bn ) Are orthogonal,
R and k are integers satisfying 1 ≦ R ≦ M and 0 ≦ k <n / M,
Part of the components of the code string Ca is
(AR,..., A (k × M + R),...)
Some of the components of the code string Cb are
(BR,..., B (k × M + R),...)
(AR,..., A (k × M + R),...) And (BR,..., B (k × M + R),.
When using MIMO of m (m is a divisor of M) system and subcarrier number for channel estimation is k,
(K mod M) mod m
And assigning the code strings Ca and Cb to the number of propagation path estimation subcarriers for each of the propagation path estimation subcarriers categorized by: .   3. The radio according to claim 2, wherein a symbol is transmitted from the same antenna by repeatedly assigning a combination of code sequences N / n times to the number N of subcarriers for channel estimation (N is a natural number). Communication method.   3. The radio communication method according to claim 2, wherein symbols are transmitted from the same antenna by assigning different combinations of code sequences to the number N of subcarriers for propagation path estimation (N is a natural number).   The radio communication according to any one of claims 2 to 4, wherein a symbol is assigned to different antenna combinations and transmitted a plurality of times within one packet to a mobile station apparatus existing in each sector. Method. n is a natural number and represents the code length of the code strings Ca and Cb, and between the divided code strings obtained by dividing the code strings Ca and Cb into M,
(A1,..., A (n / M)) and (B1,..., B (n / M)) are orthogonal to each other,
(A (n / M) +1,..., A (2n / M)) and (B (n / M) +1,..., B (2n / M)) are orthogonal to each other,
...
(A ((M−1) × n / M + 1),..., A (n)) and (B ((M−1) × n / M + 1),..., B (n)) are orthogonal. 6. The wireless communication method according to claim 2, wherein the code strings Ca and Cb satisfying all the relationships are generated.   7. The wireless communication method according to claim 1, wherein an arbitrary set of sectors is set as an adjacent sector.   Code sequences used to control three sectors adjacent to each other and estimate the propagation path in each sector are (1,1,1,1,1,1,1,1,), (1 , 1, -1, -1, -1, -1,1,1,) and (1, -1, -1, -1, -1, -1,1, -1,1), The wireless communication method according to any one of claims 1 to 7. In the case of performing MIMO communication, when the code string for propagation path estimation and data are arranged in subcarriers, either one of the propagation path estimation subcarriers existing at both ends of a single data subcarrier; Transmitting the single subcarrier for data from the same antenna;
Alternatively, one of the propagation path estimation subcarriers existing at both ends of a plurality of continuous data subcarrier groups and the plurality of continuous data subcarrier groups are transmitted from the same antenna. A wireless communication method. A receiver for receiving data transmitted by an OFDM communication method,
An FFT unit that performs fast Fourier transform on the received symbols to calculate complex information of each subcarrier, divides the complex information for each subcarrier into subcarrier groups to which a code string is assigned, and outputs the FFT information;
In the range of one code string length allocated to subcarriers for channel estimation, for each subcarrier set transmitted by different antennas in the case of the maximum number of antennas, correlation calculation is performed using the corresponding code string, And a determination unit configured to determine MIMO transmission using autocorrelation and cross-correlation of a correlation calculation result for the set.   The receiver according to claim 10, wherein the determination unit integrates autocorrelation values and cross-correlation values of correlation calculation results performed for each set in a range of one code length in a plurality of code length ranges. .   The receiver according to claim 11, wherein the determination unit sets a range of a plurality of code lengths to be integrated as a range of a minimum number of subcarriers allocated to the receiver.   The receiver according to claim 11, wherein the determination unit sets a range of a plurality of code lengths to be integrated as an entire communication band.   The receiver according to any one of claims 10 to 13, wherein MIMO transmission is also determined for adjacent sectors, and a correlation calculation method for a code string is changed.   A mobile station apparatus comprising the receiver according to claim 10. A base station apparatus that controls a plurality of sectors and performs radio communication with a mobile station apparatus according to claim 15 existing in any sector by an OFDM communication system,
A code sequence used for estimating a propagation path in one sector of an arbitrary set of sectors and a code string used for estimating a propagation path in the other sector are orthogonal to each other, and A code string generation unit that generates the code strings so that some of the components of the code strings are orthogonal to each other;
A base station apparatus comprising: a transmission unit that allocates the generated code strings to subcarriers and transmits symbols to a mobile station apparatus according to claim 15, which exists in each sector.   A radio communication system comprising the mobile station apparatus according to claim 15 and the base station apparatus according to claim 16.

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