JP4898400B2 - Wireless transmission device, wireless reception device, wireless communication system, and wireless communication method - Google Patents

Description

  The present invention relates to a radio transmission apparatus, a radio reception apparatus, a radio communication system, and a radio communication method, and in particular, a radio transmission apparatus, a radio reception apparatus, a radio communication system, and a radio communication using frequency-switched transmit diversity (FSTD). It relates to a communication method.

  In recent years, the number of users seeking to increase the speed of a wireless communication system has increased, and a multi-carrier transmission system represented by OFDM has attracted attention as one of the systems that can achieve higher speed and larger capacity. The OFDM system is a system in which tens to thousands of carriers are arranged at a minimum frequency interval where theoretically no interference occurs and information signals are transmitted in parallel by frequency division multiplexing. This OFDM scheme has the advantage that if the number of subcarriers used is increased, the symbol time becomes longer than that of a single carrier scheme having the same transmission rate, so that it is less susceptible to multipath interference.

  As one of the techniques for enhancing the frequency diversity effect in this OFDM system, transmission diversity as shown in FIG. 12 has been proposed (Non-Patent Document 1). The transmission diversity shown in FIG. 12 is transmitted from a predetermined antenna for each subcarrier or a unit in which subcarriers adjacent in the frequency direction are grouped together (referred to as a subcarrier group) in radio transmission apparatus 1200. FIG. 12 shows a state in which subcarrier group 1 and subcarrier group 3 are transmitted from antenna 1, and subcarrier group 2 and subcarrier group 4 are transmitted from antenna 2. In this way, subcarrier groups transmitted from different antennas are spatially combined, and all groups are received simultaneously by radio reception apparatus 1201. At this time, since the subcarrier groups 1 and 3 and the subcarrier groups 2 and 4 are subjected to different propagation path fluctuations, a high frequency diversity effect can be obtained. Such a technique is called frequency-switched transmission diversity FSTD (Frequency Switched Transmit Diversity).

  FIG. 13 shows the configuration of a wireless transmission device that uses frequency switching transmission diversity FSTD. However, here, an example is shown in which the number of antennas is 2, the number of subcarriers constituting a subcarrier group is 4, and the total number of subcarriers is 64. 13 includes a transmission data generation unit 1000, a diversity unit 1010, an IFFT (Inverse Fast Fourier Transform) unit 1001-a, 1001-b, and a P / S (Parallel to Serial). ) Conversion units 1002-a, 1002-b, GI (Guard Interval) insertion units 1003-a, 1003-b, D / A (Digital to Analogue) conversion units 1004-a, 1004-b RF (Radio Frequency) sections 1005-a and 1005-b and antennas 1006-a and 1006-b.

  Among these, the transmission data generation unit 1000 has a function of generating a multicarrier signal. In this method, data to be transmitted is subjected to error correction coding and modulation, and a transmission signal is mapped to each subcarrier. The multicarrier signal generated in this way is input by diversity unit 1010 to IFFT unit 1001-a or 1001-b of the antenna system predetermined for each group. In frequency switching transmission diversity FSTD, as shown in FIG. 12 as an example, adjacent subcarrier groups are set to be transmitted from different antennas. Also, among the signals input to IFFT sections 1001-a and 1001-b, zero is inserted by diversity section 1010 into subcarriers that are not transmitted by each antenna. Then, inverse fast Fourier transform processing is performed in IFFT sections 1001-a and 1001-b of each antenna system.

  Next, the P / S converters 1002-a and 1002-b perform processing for converting the signals output from the IFFT units 1001-a and 1001-b from parallel signals to serial signals, and convert the serial signals to GI. Output to the insertion sections 1003-a and 1003-b, respectively. The GI insertion units 1003-a and 1003-b insert guard intervals into the signals output from the P / S conversion units 1002-a and 1002-b, and the D / A conversion units 1004-a and 1004-b. Output to. The guard interval is mainly the time that is inserted between symbols in order to reduce the intersymbol interference of the OFDM symbol, and is usually generated by inserting the second half of the OFDM symbol at the beginning of the OFDM symbol. Is done. The D / A conversion units 1004-a and 1004-b convert the signals output from the GI insertion units 1003-a and 1003-b from digital signals to analog signals, and output them to the RF units 1005-a and 1005-b. To do. The RF units 1005-a and 1005-b frequency-convert the baseband signals output from the D / A conversion units 1004-a and 1004-b into a transmittable frequency band, and the frequency-converted high-frequency signal is the antenna 1006. -A, transmitted from 1006-b.

  Next, FIG. 14 shows the configuration of the wireless reception apparatus. 14 includes an antenna 1100, an RF unit 1101, an A / D (analogue / digital) converter 1102, a synchronization unit 1103, a GI removal unit 1104, an S / P (serial to serial). Parallel) conversion section 1105, FFT (Fast Fourier Transform) section 1106, propagation path estimation / compensation section 1107, and error correction decoding section 1108. This radio reception apparatus basically performs the reverse process of the radio transmission apparatus. Among these, the RF unit 1101 frequency-converts the high-frequency signal received by the antenna 1100 into a baseband signal and outputs the baseband signal to the A / D conversion unit 1102. The A / D conversion unit 1102 converts the analog signal output from the RF unit 1101 into a digital signal and outputs the digital signal to the synchronization unit 1103. Synchronization section 1103 performs symbol synchronization on the signal output from A / D conversion section 1102 and outputs the result to GI removal section 1104. The GI removal unit 1104 removes the guard interval added on the transmission side and outputs it to the S / P conversion unit 1105. The S / P conversion unit 1105 converts the signal output from the GI removal unit 1104 into a parallel signal having the number of points of the fast Fourier transform, and outputs the parallel signal to the FFT unit 1106. The FFT unit 1106 performs fast Fourier transform processing on the signal output from the S / P conversion unit 1105 and converts the signal into a frequency domain signal.

Next, the channel estimation / compensation unit 1107 performs channel estimation, channel compensation for each subcarrier, and demapping on the signal output from the FFT unit 1106, and performs error correction decoding on the demapped signal. Output to the unit 1108. For example, the propagation path is estimated by extracting a variation from a known pilot signal of a received signal of a known pilot signal multiplexed on a data signal. Error correction decoding section 1108 performs error correction on the signal sent from propagation path estimation / compensation section 1107, restores the transmitted data, and outputs the data. By adopting such a wireless transmission / reception apparatus configuration, it is possible to transmit by switching antennas for each subcarrier group, and subcarrier groups transmitted from different antennas are received by receiving different propagation path fluctuations. A frequency diversity effect can be obtained.
3GPP TSG RAN WG1 Meeting # 46 R1-062356

  In frequency switching transmission diversity FSTD, a high frequency diversity effect can be obtained by switching transmission antennas for each subcarrier group in which several consecutive subcarriers are combined. However, when the number of subcarriers constituting one subcarrier group is large and the propagation path fluctuation in the frequency domain is moderate, the reception level of the subcarriers in the subcarrier group drops uniformly and an error occurs. There's a problem. Further, even when the number of subcarriers constituting one subcarrier group is small, a sufficient frequency diversity effect cannot be obtained in a situation where the propagation path conditions of adjacent subcarrier groups vary similarly.

  The present invention has been made in view of such circumstances, and an object of the present invention is to achieve high frequency diversity even in a situation in which propagation path fluctuation in the frequency domain is moderate in a radio communication system using frequency switching transmission diversity FSTD. An object of the present invention is to provide a wireless transmission device, a wireless reception device, a wireless communication system, and a wireless communication method capable of obtaining the effect.

  The present invention has been made to solve the above-described problems, and a wireless transmission device according to the present invention is a transmission unit corresponding to each of a plurality of antennas, and transmits a multicarrier signal composed of a plurality of subcarriers. A wireless transmission apparatus having a plurality of means, wherein adjacent subcarriers before rearrangement are rearranged so as to be transmitted from different antennas and then transmitted.

  Thereby, since the radio transmission apparatus of the present invention transmits adjacent subcarriers before rearrangement from different antennas, when the radio reception apparatus receives the subcarriers, adjacent subcarriers before rearrangement are different. Since it is subjected to propagation path fluctuation, it is possible to transmit a signal that can obtain a high frequency diversity effect in the wireless receiver.

  Further, the wireless transmission device of the present invention is the above-described wireless transmission device, rearranges a plurality of subcarriers before relocation so that adjacent subcarriers before relocation are included in different subcarrier groups, Interleaving means for outputting a plurality of subcarrier groups composed of consecutive subcarriers after rearrangement, and diversity means for outputting adjacent subcarrier groups to transmitting means for transmitting from different antennas. Features.

Also, the wireless transmission device of the present invention is the above-described wireless transmission device, wherein the interleaving means is configured such that the subcarriers before relocation separated by a predetermined number of 2 or more differ from each other as a result of relocation. It rearranges so that it may arrange | position to a group, It is characterized by the above-mentioned.
The wireless transmission device of the present invention is the above-described wireless transmission device, wherein the predetermined number of 2 or more is the number of antennas.

  As a result, the radio transmission apparatus of the present invention arranges the subcarriers before relocation separated in the number of antennas in different subcarrier groups, so that when the radio reception apparatus receives the subcarriers, the number of antennas is separated. Further, the subcarriers before rearrangement are subjected to different propagation path fluctuations, and a signal capable of obtaining a high frequency diversity effect can be transmitted in the radio reception apparatus.

Further, the wireless transmission device of the present invention is the above-described wireless transmission device, wherein the interleaving means transmits the predetermined number of consecutive subcarriers before relocation from different antennas as a result of relocation. It is characterized by rearranging.

  As a result, since the radio transmission apparatus of the present invention transmits subcarriers before relocation corresponding to the number of continuous antennas from different antennas, when the radio reception apparatus receives the subcarriers, it corresponds to the number of continuous antennas. The subcarriers before rearrangement are subjected to different propagation path fluctuations, and a signal that can obtain a high frequency diversity effect can be transmitted in the radio reception apparatus.

  The radio reception apparatus of the present invention is characterized by receiving a plurality of subcarriers and performing reverse relocation of the relocation performed by the above-described radio transmission apparatus on these subcarriers.

  The radio communication system of the present invention is a radio communication system including a radio transmission device that transmits signals from a plurality of antennas and a radio reception device that receives signals from the radio transmission device. The subcarriers before relocation to be transmitted are rearranged so as to be transmitted from different antennas, and the radio reception device receives a plurality of subcarriers transmitted by the radio transmission device, and these subcarriers are transmitted. A reverse rearrangement of the rearrangement performed by the wireless transmission device is performed.

  The radio communication system according to the present invention is a radio communication method in a radio communication system including a transmission side that transmits signals from a plurality of antennas and a reception side that receives signals from the transmission side. A first process of transmitting the subcarriers before relocation so as to be transmitted from different antennas; and the receiving side receives a plurality of subcarriers transmitted in the first process. A radio communication method characterized by performing reverse rearrangement of the rearrangement performed in the first process on these subcarriers.

  According to the present invention, since the radio transmission apparatus transmits adjacent subcarriers before rearrangement from different antennas, adjacent subcarriers before rearrangement have different propagation path fluctuations when receiving the subcarriers. The signal which can receive and can obtain the high frequency diversity effect in the receiving side can be transmitted.

  Also, according to the present invention, since the radio receiving apparatus receives adjacent pre-relocation subcarriers transmitted from different antennas, the adjacent sub-relocation subcarriers are subjected to different propagation path fluctuations and are high. A frequency diversity effect can be obtained.

The present invention is a subcarrier interleaving capable of obtaining a high frequency diversity effect in frequency switching transmission diversity FSTD without depending on the number of subcarriers constituting a subcarrier group or propagation path fluctuations received by adjacent subcarrier groups. It is about the method. Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is a schematic block diagram showing the configuration of a wireless transmission device according to the first embodiment of the present invention. However, the number of antennas is two. In FIG. 1, the number of subcarriers included in one subcarrier group is n. As shown in FIG. 1, the radio transmission apparatus according to the present embodiment includes transmission data generation section 1000, subcarrier interleaving section 100, diversity section 1010, IFFT sections 1001-a and 1001-b, and P / S conversion section 1002-. a, 1002-b, GI insertion units 1003-a, 1003-b, D / A conversion units 1004-a, 1004-b, RF units 1005-a, 1005-b, antennas 1006-a, 1006-b Is done.

  In this embodiment, the IFFT unit 1001-a, the P / S conversion unit 1002-a, the GI insertion unit 1003-a, the D / A conversion unit 1004-a, and the RF unit 1005-a correspond to the antenna 1006-a. It functions as a transmission means. Similarly, IFFT section 1001-b, P / S conversion section 1002-b, GI insertion section 1003-b, D / A conversion section 1004-b, and RF section 1005-b transmit means corresponding to antenna 1006-b. Function as.

  The transmission data generation unit 1000 has a function of generating a multicarrier signal. In this method, data to be transmitted is subjected to error correction coding, further subjected to modulation such as two-phase phase modulation (BPSK) and four-phase phase modulation (QPSK), and a transmission signal is mapped to each subcarrier. Subcarrier interleaving section (interleaving means) 100 rearranges the subcarriers (subcarriers before relocation) obtained by dividing the multicarrier signal generated by transmission data generating section 1000 into frequency units in a predetermined order in the frequency direction. And rearrange. This rearrangement is performed by referring to a table in which the relationship between sub-carrier numbers before and after rearrangement is stored by executing a program by a general-purpose processing unit such as a CPU. Output the output signal corresponding to the position after the rearrangement of the output signal for each subcarrier from the buffer storing the output signal of the transmission data generation unit 1000 It can be realized by a method such as providing a dedicated circuit connected to. Details of subcarrier interleaving section 100 will be described later.

  Diversity unit (diversity means) 1010 includes subcarriers rearranged by subcarrier interleaving unit 100 (subcarriers after rearrangement) IFFT unit 1001-a of the antenna system predetermined for each subcarrier group or Input to 1001-b. In frequency switching transmission diversity FSTD, as shown in FIG. 1 as an example, adjacent subcarrier groups are set to be transmitted from different antennas. Also, among the signals input to IFFT sections 1001-a and 1001-b, zero (a signal having a value of “0”) is inserted by diversity section 1010 into subcarriers that are not transmitted by each antenna. Then, inverse fast Fourier transform processing is performed in IFFT sections 1001-a and 1001-b of each antenna system. In addition, since a subcarrier group is a group comprised from the subcarrier adjacent to the frequency direction at the time of transmission, it can also be said to be comprised from the subcarrier after rearrangement adjacent to the frequency direction.

  Next, the P / S converters 1002-a and 1002-b perform processing for converting the signals output from the IFFT units 1001-a and 1001-b from parallel signals to serial signals, and convert the serial signals to GI. Output to the insertion sections 1003-a and 1003-b, respectively. The GI insertion units 1003-a and 1003-b insert guard intervals into the signals output from the P / S conversion units 1002-a and 1002-b, and the D / A conversion units 1004-a and 1004-b. Output to. The guard interval is mainly the time that is inserted between symbols in order to reduce intersymbol interference of the OFDM symbol. As an example, the latter part of the OFDM symbol is inserted at the beginning of the OFDM symbol. Generated. The D / A conversion units 1004-a and 1004-b convert the signals output from the GI insertion units 1003-a and 1003-b from digital signals to analog signals, and output them to the RF units 1005-a and 1005-b. To do. The RF units 1005-a and 1005-b frequency-convert the baseband signals output from the D / A conversion units 1004-a and 1004-b into a transmittable frequency band, and the frequency-converted high-frequency signal is the antenna 1006. -A, transmitted from 1006-b.

  Thus, in the radio transmission apparatus according to the present embodiment, before diversity section 1010 inputs each subcarrier (group) to a predetermined antenna system (IFFT section 1001-a or IFFT section 1001-b). The subcarrier interleaving unit 100 is configured to perform interleaving. In this way, the present invention allows subcarriers to be grouped into several subcarrier groups and interleaved before being input only to the system of antennas to be transmitted, so that adjacent or not so distant subcarriers can be obtained. It is possible to transmit from different antennas and to obtain a high frequency diversity effect. The operation of subcarrier interleaving section 100 will be described later.

  Next, FIG. 2 shows the configuration of the wireless reception apparatus according to this embodiment. As shown in FIG. 2, the radio reception apparatus according to the present embodiment includes an antenna 1100, an RF unit 1101, an A / D conversion unit 1102, a synchronization unit 1103, a GI removal unit 1104, an S / P conversion unit 1105, and an FFT unit 1106. , A propagation path estimation / compensation unit 1107, a subcarrier deinterleave unit 200, and an error correction decoding unit 1108. The RF unit 1101 converts the frequency of the signal received by the antenna 1100 into a baseband signal and outputs it to the A / D conversion unit 1102. The A / D conversion unit 1102 converts the analog signal output from the RF unit 1101 into a digital signal and outputs the digital signal to the synchronization unit 1103. Synchronization section 1103 performs symbol synchronization on the signal output from A / D conversion section 1102 and outputs the result to GI removal section 1104. The GI removal unit 1104 removes the guard interval added on the transmission side and outputs it to the S / P conversion unit 1105. The S / P conversion unit 1105 converts the signal output from the GI removal unit 1104 into a parallel signal having the number of points of the fast Fourier transform, and outputs the parallel signal to the FFT unit 1106. The FFT unit 1106 performs fast Fourier transform processing on the signal output from the S / P conversion unit 1105 and converts the signal into a frequency domain signal.

  Next, propagation path estimation / compensation section 1107 performs propagation path estimation, propagation path compensation for each subcarrier, and demapping on the signal output from FFT section 1106, and outputs the demapped signal to subcarrier demultiplexing. Output to the interleave unit 200. However, propagation path estimation is performed, for example, by extracting a variation of a received signal of a known pilot signal multiplexed on a data signal from a known pilot signal. The subcarrier deinterleaving unit 200 performs rearrangement on the demapped signal so that the rearrangement by the subcarrier interleaving unit 100 of the wireless transmission device is reversed, and performs error correction decoding on the result. Output to the unit 1108. Similar to the subcarrier interleaving unit 100, this rearrangement is performed by referring to a table in which the relationship between the position (subcarrier number) before and after the rearrangement is stored when a general-purpose processing unit such as a CPU executes a program. Then, the contents of the buffer storing the output signal of the propagation path estimation / compensation unit 1107 are rearranged and output, or the output of each subcarrier of the buffer storing the output signal of the propagation path estimation / compensation unit 1107 is output. It can be realized by a method such as providing a dedicated circuit connected to an output corresponding to a position after rearrangement of signals. Error correction decoding section 1108 performs error correction on the signal sent from subcarrier deinterleaving section 200 and restores the transmitted data.

  Thus, in the radio reception apparatus, the transmitted data can be correctly demodulated by providing the subcarrier deinterleaving unit 200 corresponding to the radio transmission apparatus shown in FIG. However, when pilot signals for channel estimation are inserted in all subcarriers, a subcarrier deinterleave unit 200 is provided before the channel estimation / compensation unit 1107, and the pilot signal is the same as the data signal. It is good also as a structure which deinterleaves.

Here, the interleaving operation by subcarrier interleaving section 100 will be described. In the present invention, the most basic subcarrier rearrangement operation of the subcarrier interleaving unit 100 is to rearrange so that adjacent subcarriers are in different subcarrier groups. A high frequency diversity effect can be obtained when rearrangement is performed so as to be transmitted from the network. This rearrangement criterion can be expressed as shown in the following formula (1). Here, K represents the number of subcarriers, and M (k) represents the antenna number for transmitting the kth subcarrier before rearrangement.
M (k + 1) ≠ M (k) (k = 1, 2, 3,..., K−1) (1)
When the rearrangement criterion shown in Expression (1) is followed, rearrangement is performed so that adjacent subcarriers are transmitted from different antennas.

  Here, the basic operation of rearranging adjacent subcarriers so as to transmit from different antennas is shown in FIG. However, FIG. 3 shows an example where n = 4, where n is the number of subcarriers constituting one subcarrier group. FIG. 3 transmits an input a1 (subcarrier sequence before relocation) to subcarrier interleave section 100 from the bottom, an output b1 (subcarrier sequence after rearrangement) from subcarrier interleave section 100, and each subcarrier group. Antenna name c1, propagation path response d1 of each subcarrier, output e1 (subcarrier sequence after deinterleaving) from subcarrier deinterleaving section 200 in the radio reception apparatus, and reception level f1 after deinterleaving, respectively. .

  Note that the squares in the input a1 to the subcarrier interleaving unit 100, the output b1 from the subcarrier interleaving unit 100, the propagation path response d1 of each subcarrier, and the output e1 from the subcarrier deinterleaving unit 200 and the numbers in the squares are The square represents the subcarrier, and the number represents the subcarrier number. For example, at the input a1 to the subcarrier interleaving unit 100, the first subcarrier 1 is arranged as it is even at the output b1 from the subcarrier interleaving unit 100 as it is. Further, the second subcarrier 2 is arranged at the fifth (subcarrier group 2) in the output b1 from the subcarrier interleaving unit 100 at the input a1 to the subcarrier interleaving unit 100. In the input a1 to the subcarrier interleaving unit 100, the third subcarrier 3 is arranged in the second (subcarrier group 1) in the output b1 from the subcarrier interleaving unit 100.

The rearrangement operation of the subcarrier interleaving unit 100 can be expressed by the following equation. Here, i represents a subcarrier number before interleaving, j represents a subcarrier number after interleaving, and n represents the number of subcarriers constituting one subcarrier group. Floor (x) represents an integer not exceeding x, and mod (x, y) represents a remainder obtained by dividing x by y.
j = 4 × 2 × floor ((i−1) ÷ (4 × 2)) + mod (mod (i, 2) +1,2) × 4 + mod (floor ((i−1) ÷ 2), 4) +1

  Here, it can be said that the propagation path response d1 of each subcarrier shown in FIG. 3 represents the reception level of each subcarrier when subcarrier interleaving is not performed. As shown in the channel response d1 of each subcarrier, when the subcarrier interleaving according to the present invention is not used in combination with the frequency switching transmission diversity FSTD, subcarriers with low reception levels such as subcarriers 1 to 4 are consecutive. Even if the signal sequence is input to the error correction decoding unit 1108 such as a Viterbi decoder as it is, a sufficient frequency diversity effect cannot be obtained, so that many bits in the encoding unit are missing or error. Therefore, the probability that error correction cannot be performed effectively increases.

  On the other hand, the subcarrier interleaving unit 100 rearranges so that adjacent subcarriers are transmitted from different antennas, such as from the input a1 to the subcarrier interleaving unit 100 to the output b1 from the subcarrier interleaving unit 100. By performing the above, it is possible to reduce the probability that subcarriers having a low reception level continue as shown by the reception level f1 after deinterleaving. This is because signals transmitted from different antennas undergo different variations in the propagation path. The frequency diversity effect thus obtained makes it possible to make error correction by the error correction decoding unit 1108 effective and reduce the occurrence of errors.

  As described above, by applying an interleaving method in which adjacent subcarriers are rearranged in different subcarrier groups, and in particular rearranged so that transmission is performed from different antennas, propagation path fluctuations of adjacent subcarriers become different. It is possible to enhance the frequency diversity effect by the frequency switching transmission diversity FSTD.

[Second Embodiment]
In the first embodiment, the frequency diversity effect by the frequency switching transmission diversity FSTD can be enhanced by applying an interleaving method in which rearrangement is performed so as to transmit from different antennas. However, the frequency diversity effect obtained in a situation where adjacent subcarrier groups among the subcarrier groups transmitted from different antennas are subjected to similar propagation path fluctuations decreases. Specifically, like the subcarriers 25 to 32 shown in the reception level f1 after deinterleaving in FIG. 3, subcarriers having the same reception level after deinterleaving will continue. Therefore, in the second embodiment, a wireless communication system capable of obtaining a high frequency diversity effect even in such a situation will be described.

FIG. 4 is a schematic block diagram showing a configuration of a wireless transmission device according to the second embodiment of the present invention. In the figure, portions corresponding to the respective portions in FIG. Reference numeral 101 denotes a subcarrier interleaving unit (interleaving unit) that rearranges the subcarriers obtained by dividing the multicarrier signal generated by the transmission data generation unit 1000 into frequency units, rearranged in a predetermined order in the frequency direction. . Details of the interleaving method performed by the subcarrier interleaving unit 101 will be described in detail with reference to FIG.
FIG. 5 is a schematic block diagram illustrating the configuration of the wireless reception device according to the present embodiment. In the figure, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted. 201 performs rearrangement that reversely rearranges the signal output from the propagation path estimation / compensation unit 1107 so that the rearrangement by the subcarrier interleaving unit 101 of the wireless transmission device is restored, and corrects the result. It is a subcarrier deinterleaving unit according to this embodiment that is output to the decoding unit 1108.

  FIG. 6 shows, from the bottom, an input a2 (subcarrier string before interleaving) to subcarrier interleaving section 101, an output b2 (subcarrier string after interleaving) from subcarrier interleaving section 101, and an antenna for transmitting each subcarrier group The name c2, the channel response d2 of each subcarrier, the output e2 (subcarrier sequence after deinterleaving) from the subcarrier deinterleaving unit 201 in the radio reception apparatus, and the reception level f2 after deinterleaving are shown. The squares in the input a2 to the subcarrier interleaving unit 101, the output b2 from the subcarrier interleaving unit 101, the channel response d2 of each subcarrier, and the output e2 from the subcarrier deinterleaving unit 201, and the numbers in the squares are squares Represents a subcarrier, and a number represents a subcarrier number.

In the interleaving method shown in FIG. 6, subcarrier interleaving section 101 arranges adjacent subcarriers to be transmitted from different antennas, and arranges subcarriers separated by the number of antennas in different subcarrier groups. Sort as follows. This is because, in this embodiment, the number of antennas is 2, so that a plurality of subcarriers separated by two subcarriers, such as subcarrier 1 and subcarrier 3 and subcarrier 2 and subcarrier 4 in FIG. The related subcarriers are rearranged so that they are arranged in different subcarrier groups. This rearrangement standard can be expressed by a combination of Formula (1) and the following Formula (2). Here, L represents the number of transmission antennas, and g (k) represents the number of the subcarrier group in which the kth subcarrier before rearrangement is included after rearrangement.
g (k + L) ≠ g (k) (k = 1, 2, 3,..., KL) (2)
When the rearrangement criteria shown in Equations (1) and (2) are followed, rearrangement is performed so that subcarriers separated by the number of antennas are arranged in different subcarrier groups and adjacent subcarriers are transmitted from different antennas. It is done.

The rearrangement operation shown in FIG. 6, which is an example of the rearrangement operation that satisfies the rearrangement criteria shown in Expression (1) and Expression (2), can be specifically expressed by the following expression. Here, i indicates a subcarrier number before interleaving, and j indicates a subcarrier number after interleaving.
j = 4 × 4 × floor ((i−1) ÷ (4 × 4)) + mod (mod (i−1,4), 4) × 4 + mod (floor ((i−1) ÷ 2), 4) +1
As described above, when the rearrangement operation method that satisfies the rearrangement criteria shown in the equations (1) and (2) is used, after the deinterleaving, as shown in the reception level f2 after the deinterleaving in FIG. It is possible to prevent a situation in which a number of signals having the same reception level continue (subcarriers 25 to 32).

  This is because the subcarriers with greatly different frequencies receive different propagation path variations. Therefore, the frequency diversity effect can be sufficiently obtained even in a situation where adjacent subcarrier groups are subjected to the same propagation path fluctuation. However, such interleaving cannot be applied when the number of subcarrier groups is very small, for example, when the number of subcarrier groups is 2, and is effective when the number of subcarrier groups is large to some extent. Technology.

  In the example shown in FIG. 6, the rearrangement is performed so that the subcarriers separated by the number of antennas are separated by two subcarrier groups. However, the subcarriers may be arranged in more distant subcarrier groups. In this way, by arranging the subcarrier groups in more distant subcarrier groups, the effect of frequency diversity can be obtained even in a propagation path situation where the fluctuation is very gradual.

  In addition, since the rearrangement by the subcarrier interleaving unit 101 in the present embodiment shown in FIG. 6 satisfies the formula (1) as described above, similarly to the subcarrier interleaving unit 100 according to the first embodiment, Adjacent subcarriers are rearranged in different subcarrier groups. For this reason, as in the first embodiment, the propagation path fluctuations of adjacent subcarriers are different, and the frequency diversity effect by the frequency switching transmission diversity FSTD can be enhanced.

[Third Embodiment]
In the first and second embodiments, an example in which the number of antennas is 2 is shown, but in the third embodiment, an example of subcarrier interleaving in the case where the number of antennas is 4 is shown. FIG. 7 is a schematic block diagram illustrating a configuration of a wireless transmission device according to the third embodiment. The wireless transmission device according to the present embodiment is the transmission system (IFFT unit 1001-a, P / S conversion unit 1002-a, GI insertion unit 1003-a, D / A conversion unit 1004-a of the wireless transmission device shown in FIG. , The RF unit 1005-a and the antenna 1006-a) are increased to four sets. In FIG. 7, parts corresponding to those in FIG. Reference numeral 102 denotes a subcarrier interleaving unit that performs subcarrier interleaving in the present embodiment. Details of subcarrier interleaving section 102 will be described later with reference to FIG. 1011 is a diversity in which each subcarrier interleaved by the subcarrier interleaving unit 102 is allocated in order to four IFFT units of IFFT units 1001-a, 1001-b, 1001-c, and 1001-d for each subcarrier group. Part.

  FIG. 8 is a schematic block diagram illustrating the configuration of the wireless reception device according to the present embodiment. In the figure, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 202 denotes a subcarrier deinterleaving unit that rearranges subcarriers so as to restore interleaving by the subcarrier interleaving unit 102 of the wireless transmission device in the present embodiment.

  Here, before explaining the interleaving method in this embodiment, an example of subcarrier numbers before and after interleaving when the subcarrier interleaving shown in the second embodiment is applied to a radio transmission apparatus having four antennas is shown. 9 shows. In the second embodiment, rearrangement is performed so that adjacent subcarriers are rearranged so as to be transmitted from different antennas, and subcarriers separated by the number of antennas are arranged in different subcarrier groups. . When interleaving is performed by this method, as shown in FIG. 9, subcarriers located relatively close like subcarrier 1 and subcarrier 3 are transmitted from the same antenna 1 (belonging to the same subcarrier group). Interleaving may be performed. Even in such a case, a high frequency diversity effect can be obtained if the propagation path fluctuations received by the signals transmitted from the respective antennas are independent from each other. However, subcarriers located near each other can be transmitted from different antennas (or from different antennas). By interleaving to be transmitted (in a subcarrier group), a higher frequency diversity effect can be obtained. An example in the case of performing interleaving according to the present embodiment considering the above is shown in FIG.

As shown in FIG. 10, in the interleaving by the subcarrier interleaving unit 102 of this embodiment, in addition to the interleaving shown in the second embodiment, the number of consecutive subcarriers is the same as the number of antennas (here, 4). Rearrange it so that it is transmitted from the antenna. For example, there are subcarriers 7 to 10 and subcarriers 9 to 12 as a set of four consecutive subcarriers including the subcarrier 10. However, in the interleaving shown in FIG. 10, the four consecutive subcarriers are all different. Transmitting from the antenna (subcarrier 7 from antenna 1006-c, subcarrier 8 from antenna 1006-d, subcarrier 9 from antenna 1006-a, subcarrier 10 from antenna 1006-b, subcarrier 11 Are rearranged so as to be transmitted from antenna 1006-c and subcarrier 12 from antenna 1006-d, respectively. This rearrangement criterion can be expressed by a combination of Expression (2) and the following Expression (3).
M (k + L-1) .noteq.M (k + L-2) .noteq. ≠ M (k + 1) .noteq.M (k)
(K = 1, 2, 3,..., K−L + 1) (3)

  The reception level when each subcarrier interleaved and transmitted in this way undergoes propagation path fluctuation indicated by the propagation path response d4 and is deinterleaved on the receiving side is the reception level f4 after deinterleaving. . By performing interleaving and deinterleaving according to the present embodiment, the probability that consecutive subcarriers having a low reception level after deinterleaving can be greatly reduced as indicated by reception level f4 after deinterleaving. This is because the subcarriers located relatively close to each other (continuous by the number of antennas) are rearranged so that they are transmitted from different antennas. Due to the effect of frequency diversity obtained in this way, error correction by the error correction decoding unit 1108 can be made effective and the occurrence of errors can be greatly reduced. However, as described in the first embodiment, such interleaving cannot be applied when the number of subcarrier groups is very small, for example, when the number of subcarrier groups is two. This is effective when the number of subcarrier groups is large to some extent.

The rearrangement operation shown in FIG. 10, which is an example of the rearrangement operation that satisfies the rearrangement criteria shown in Expression (2) and Expression (3), can be specifically expressed by the following expression. Here, i indicates a subcarrier number before interleaving, and j indicates a subcarrier number after interleaving.
j = mod (mod (i−1,8), 8) × 4 + mod (floor ((i−1) ÷ 8), 8) +1
Further, another example of the present embodiment represented by a combination of Expression (2) and Expression (3) is shown in FIG. In FIG. 11, as in the example shown in FIG. 10, rearrangement is performed so that the same number of subcarriers as the number of antennas (here, 4) are transmitted from different antennas. That is, as a result of the rearrangement in FIG. 11, the subcarrier numbers 1, 2, 3,... 32 before interleaving are arranged in the order of subcarrier numbers 1, 9, 17, 25, 3, 11, 19 after interleaving. 27, 2, 10, 18, 26, 4, 12, 20, 28, 5, 13, 21, 29, 7, 15, 23, 31, 5, 14, 22, 30, 8, 16, 23, 32 It becomes.

  In addition, since Formula (3) includes Formula (1), when Formula (3) is materialized, Formula (1) is always materialized. Therefore, the rearrangement by the subcarrier interleaving unit 102 in this embodiment shown in FIG. 10 and FIG. 11 is similar to the subcarrier interleaving unit 100 according to the first embodiment. Rearranged. For this reason, as in the first embodiment, the propagation path fluctuations of adjacent subcarriers are different, and the frequency diversity effect by the frequency switching transmission diversity FSTD can be enhanced.

  Further, since Expression (3) includes Expression (1), the rearrangement by the subcarrier interleave unit 102 in the present embodiment illustrated in FIGS. 10 and 11 is based on Expression (1) and Expression (2). According to the relocation standard, subcarriers separated by the number of antennas are arranged in different subcarrier groups, and adjacent subcarriers are transmitted from different antennas, and several signals with the same reception level after deinterleaving. A continuous situation can be prevented.

  In the embodiment described above, the subcarrier interleaving unit 100 in FIG. 1, the diversity unit 1010, the subcarrier deinterleaving unit 200 in FIG. 2, the subcarrier interleaving unit 101 in FIG. 4, the diversity unit 1010, and the subcarrier deinterleaving in FIG. Unit 201, subcarrier interleaving unit 102 in FIG. 7, diversity unit 1011 and subcarrier deinterleaving unit 202 in FIG. 8 or a program for realizing a part of these functions is recorded on a computer-readable recording medium. Then, the program recorded in the recording medium may be read into the computer system and executed to execute the processing of each unit. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” dynamically holds a program for a short time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, it is also assumed that a server that holds a program for a certain time, such as a volatile memory inside a computer system that serves as a server or client. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  The present invention is suitable for use in a mobile communication system in which a wireless transmission device is a base station device and a wireless reception device is a mobile station device, but is not limited thereto.

It is a schematic block diagram which shows the structure of the radio | wireless transmission apparatus by 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the radio | wireless receiving apparatus in the embodiment. It is the figure which showed the interleaving by the subcarrier interleaving part 100 in the embodiment, and the distribution of the reception level of the result. It is a schematic block diagram which shows the structure of the radio | wireless transmitter by 2nd Embodiment of this invention. It is a schematic block diagram which shows the structure of the radio | wireless receiving apparatus in the embodiment. It is the figure which showed the distribution of the reception level of the interleaving by the subcarrier interleaving part 101 in the same embodiment, and the result. It is a schematic block diagram which shows the structure of the radio | wireless transmitter by 3rd Embodiment of this invention. It is a schematic block diagram which shows the structure of the radio | wireless receiving apparatus in the embodiment. It is a figure explaining the case where the interleaving similar to 2nd Embodiment is performed when there are four antennas. It is the figure which showed distribution of the interleaving by the subcarrier interleaving part 102 in 3rd Embodiment, and the result of the reception level. It is the figure which showed another example of the interleaving by the subcarrier interleaving part 102 in 3rd Embodiment. It is a figure explaining the outline | summary of the frequency switching transmission diversity FSTD. It is a schematic block diagram which shows the structure of a radio | wireless transmitter. It is a schematic block diagram which shows the structure of a radio | wireless receiving apparatus.

Explanation of symbols

100, 101, 102 ... subcarrier interleaving unit 200, 201, 202 ... subcarrier deinterleaving unit 1000 ... transmission data generating unit 1001-a, 1001-b, 1001-c, 1001-d ... IFFT unit 1002-a, 1002 -B, 1002-c, 1002-d ... P / S converters 1003-a, 1003-b, 1003-c, 1003-d ... GI insertion units 1004-a, 1004-b, 1004-c, 1004-d ... D / A conversion unit 1005-a, 1005-b, 1005-c, 1005-d ... RF unit 1006-a, 1006-b, 1006-c, 1006-d ... antenna 1010, 1011 ... diversity unit 1100 ... antenna 1101... RF section 1102... A / D conversion section 1103... Synchronization section 1104. 5 ... S / P converting unit 1106 ... FFT unit 1107 ... propagation channel estimation and compensation unit 1108 ... error correction decoding unit 1200 ... wireless transmission apparatus 1201 ... wireless reception apparatus

Claims (2)

A radio transmission apparatus having a plurality of transmission means corresponding to a plurality of antennas and transmitting a multicarrier signal composed of a plurality of subcarriers,
Interleaving means for rearranging a plurality of subcarriers before rearrangement so that adjacent subcarriers before rearrangement are included in different subcarrier groups and outputting a plurality of subcarrier groups composed of consecutive subcarriers after rearrangement When,
Diversity means for outputting adjacent subcarrier groups to transmitting means for transmitting from different antennas;
Comprising
The radio transmitting apparatus according to claim 1, wherein the interleaving section rearranges so that subcarriers before rearrangement separated by the number of antennas are arranged in different subcarrier groups as a result of rearrangement. 2. The radio according to claim 1 , wherein the interleaving section rearranges the subcarriers so that consecutive subcarriers corresponding to the number of antennas are transmitted from the different antennas as a result of the rearrangement. Transmitter device.

Images