WO2008029704A1

WO2008029704A1 - Transmission device, reception device, communication system, and communication method

Info

Publication number: WO2008029704A1
Application number: PCT/JP2007/066889
Authority: WO
Inventors: Ryota Yamada; Takashi Yoshimoto; Minoru Kubota; Takashi Onodera; Toshizo Nogami
Original assignee: Sharp Kabushiki Kaisha
Priority date: 2006-09-06
Filing date: 2007-08-30
Publication date: 2008-03-13

Abstract

A transmission device includes: a spread unit for spreading a transmission symbol by using a spread code so as to generate a signal of each chip for each channel; a code multiplexing unit for multiplexing chip signals of a plurality of channels so as to generate a multiplexed signal; and an interleaver unit for rearranging the order of the multiplexed signals in the spread direction by using a group of multiplexed signals adjacent in the spread direction having a smaller number of chips than the spread ratio of the spread code as a unit. It is possible to obtain a frequency diversity effect and accurately obtain a symbol from the code-multiplexed signals at the reception side.

Description

Specification

Transmitting apparatus, receiving apparatus, communication system, and communication method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a transmission device, a reception device, a communication system, and a communication method, and more particularly to a transmission device, a reception device, a communication system, and a communication method that perform communication using a signal that has been spread using a spreading code and then interleaved.

This application (September, 2006, patent application No. 2006-242105, filed on June 6, 2006, and Takashi Enomoto claimed priority and incorporated herein by reference.

Background art

Conventionally, for example, on the transmission side of MC-CDMA (Multi-Carrier Code Division Multiple Access) or OFCDM (Orthogonal Frequency and Code Division Multiplexing), information symbols are repeated on continuous subcarriers corresponding to the spreading factor ( Copy) and multiply the repeated subcarriers by the spreading code (hereinafter referred to as frequency axis spreading). Since the subcarrier symbols are frequency-axis spread with separable spreading codes, code multiplexing can be performed. On the receiving side, demodulation is performed by extracting the desired information symbol by despreading using a spreading code in which the desired information symbol is spread, and restoring the information transmitted on each subcarrier. . The MC-CDMA system and OFCDM system that operate as described above are described in Non-Patent Document 1, for example. MC-CDMA and OFCDM receivers need to maintain good orthogonality between spreading code sequences in order to obtain information symbols accurately from code-multiplexed signals. .

[0003] In addition, in a communication system, in order to improve the performance of an error correction code by obtaining a diversity effect, interleaving for rearranging signals in the time direction or frequency direction is usually performed on the transmission side, and the original is performed on the reception side. Perform a Dinter Leave to return. This interleaving / dinterleaving includes, for example, chip interleaving that rearranges in the frequency direction in units of chips, and symbol interleaving that rearranges in the frequency direction in units of symbols before spreading. In these interleavings, frequency selective features with large frequency fluctuations are used. Since fluctuation similar to ging occurs in the rearrangement unit, the frequency diversity effect in units of chips can be obtained with chip interleaving, and the frequency diversity effect in units of symbols can be obtained with symbol interleaving. These interleaves are described in Non-Patent Document 2.

Non-Patent Document 1: Maeda, Shin, Abeda, Sawahashi, "VSF using OFD-OFCDM and its characteristics", IEICE Technical Report RCS2002-61, May 2002

Non-Patent Document 2: Maeda, H. Atarashi, M. sawahashi, Performance Comparison of Channel Interleaving Methods in Frequency Domain for VSF-OFCDM Broadband Wireless Access in Forward Link, IEICE trans, commun., Vol. E86-B, No. 1, Jan. 200 3

Disclosure of the invention

Problems to be solved by the invention

[0004] The relationship between the spreading code and the frequency variation will be described. The upper part of Fig. 7 multiplexes 3 code channels via a propagation path in an ideal frequency-selective fading environment with no frequency fluctuation on the coordinate plane with the horizontal axis representing frequency and the vertical axis representing received power. The received power frequency characteristics of the received signal are illustrated. For the convenience of explanation, the received signal indicates 8 chips on the frequency axis. These 8 chips are obtained by spreading one symbol. As shown in the lower part of FIG. 7, the symbol “1” is spread in each of the three code channels with spreading factor SF = 8 and orthogonal code spreading code C = [1 1 1 1 1 1 1 1], C = [1 1 1

8, 1 8, 2

1 -1 -1 -1 —i], c = [1 -1 -1 1 1 -1 -1 1]

8, 7

The signals received in the environment shown in the upper part of Fig. 7 are spread codes C and C, respectively.

8, 1

, C itself.

8, 2 8, 7

Figure 8 shows the received signal described in Figure 7 multiplied by the spreading code C to perform inverse expansion.

8, 1

The calculation result when scattered is shown. The value “8” is obtained for signal C, and

The value “0” is obtained for 8, 1 8, 2 and the value “0” is obtained for signal C. This operation is expressed in equation (11)

8, 7

Show again.

[0005] [Equation 1]

rc ¹ -π

[0006] ^Here , ^Τ represents transposition of a matrix. Thus, from equation (11), when spreading and code multiplexing using orthogonal codes, the correlation with other than the own code channel is 0 when despreading, so the codes are orthogonal. The symbol of the spreading code C code channel.

8, 1

You can. Here, for the sake of convenience, the power described to multiply the component separated into each code channel by the spreading code is actually the received signal (c

8, 1

Multiply + C + C) by the spreading code of the desired code channel. Ie spreading code

8, 2 8, 7

To retrieve the code channel symbol corresponding to C, (c + c + c) -c

8, 1 8, 1 8, 2 8, 7 8

Calculate ^T = 8. This equation is (C + C + C) -C ^T = C

, 1 8, 1 8, 2 8, 7 8, 1 c ^T + cc ^T + cc ^T , which is equal to the sum of the equations (11). This is the following

8, 1 8, 1 8, 2 8, 1 8, 7 8, 1

The same applies to the descriptions of FIGS. 9, 10, and 11.

[0007] FIG. 9 shows an example of a received signal when frequency fluctuation occurs in the spreading code. The upper part of Fig. 9 shows the received signal that has passed through the propagation path in a frequency selective fading environment with frequency fluctuations in the spread code on the coordinate plane with the horizontal axis representing frequency and the vertical axis representing received power. The received power frequency characteristics are illustrated. The received signal indicates 8 chips on the frequency axis for convenience of explanation. These 8 chips are chips obtained by spreading one symbol. In the example of Fig. 9, the received signals for four chips with low frequency are hardly affected by the propagation path, as in the case of Fig. 7 above, but the received signals for four chips with high frequency are The received power is extremely reduced due to the strong attenuation caused by. Therefore, as shown in the lower part of Fig. 9, the signal with the symbol "1" spread by spreading codes C, C, C

8, 1 8, 2 8, 7

Are signals C, = [1 1 1 1 0 0 0 0], C, = [1 1 1 1 0 0, respectively.

8, 1 8, 2

0 0], C, = [1 -1 -1 1 0 0 0 0]. A receiver containing these three signals.

8, 7

When despreading is performed by multiplying the received signal by C = [1 1 1 1 1 1 1 1]

8, 1

The value "4" is obtained for C, the value "4" is obtained for signal C ', and the signal C'

For 8, 1 8, 2 8, 7 the value “0” is obtained. This operation is shown again in equation (12). [0008] [Equation 2]

Q.iQ.i 4

Yes. 2 S {4.

[0009] From equation (12), when despreading a code channel that has been subject to fluctuation,

8, 2

Inter-code interference MCI has occurred.

Next, the disadvantages of the symbol interleaver and chip interleaver will be described based on the relationship between the above-described spreading code and frequency fluctuation. FIG. 10 is a diagram for explaining the symbol interleaver. The upper part of Fig. 10 shows the case where a symbol interleaver is used, and the signal passes through a propagation path in a frequency-selective fading environment with frequency fluctuations in the coordinate plane with the horizontal axis representing frequency and the vertical axis representing received power. The received power frequency characteristics of the received signal are shown for the Dinterleave operation on the receiving side. For convenience of explanation, the received signal shows 16 chips equivalent to 2 symbols on the frequency axis. Since the symbol interleaver performs rearrangement for each symbol, the eight received chips that remain adjacent on the frequency axis before and after the rearrangement receive almost the same received power with almost no influence of frequency fluctuations. It becomes.

Symbol 1 (8 chips on the lower frequency side in 16 chips) and Symbol 2 (8 chips on the higher frequency side in 16 chips) are placed in different frequency regions due to symbol interleaving. Among these, the received power tends to be different due to the influence of frequency fluctuation.

For this reason, as shown in the upper part of FIG. 10, each chip of symbol 1 can obtain sufficient received power, whereas each chip of symbol 2 is sufficiently attenuated to obtain sufficient received power. Not happen. At this time, in symbol 1, the symbol “1” is spread with the spreading code C = [1 1 1 1 1 1 1 1] C = [1-1-1 1 1-1-1 1]

8, 1 8, 7

Each of the received signals is the spreading code C C itself. Like this 2

8, 1 8, 7

When the received signal containing two signals is multiplied by the spreading code C, "8" for signal C

8, 1 8, 1

And “0” is obtained for signal C. On the other hand, in symbol 2, symbol “1” is spread by spreading code C.

Expanded by 8, 1 and C

The received signals of 8 and 7 are “0 0 0 0 0 0 0 0” and “0 0 0 0 0 0 0”, respectively.

0 ”. Even if the received signal containing these two signals is multiplied by spreading code C, either

8, 1

They will also be “0”. In this way, in the symbol interleaver, as shown in FIG. 10, the power of Symphony 1 can be obtained with good results.Symbol 2 cannot be demodulated correctly because the reception level is low! . This is true even in the case of no code multiplexing! /.

FIG. 11 is a diagram illustrating a chip interleaver. The upper part of Fig. 11 shows the propagation path in a frequency-selective fading environment with frequency fluctuations in the coordinate plane with the horizontal axis representing frequency and the vertical axis representing received power when a chip interleaver is used. This figure shows the received power frequency characteristics of the received signal that passed through, for the Dinterleave operation on the receiving side. For convenience of explanation, the received signal shows 16 chips equivalent to 2 symbols on the frequency axis. Since the chip interleaver performs rearrangement for each chip, it is placed in a different frequency region for each chip due to rearrangement. Therefore, the received power varies from chip to chip under the influence of frequency fluctuations. Cheap.

[0013] Therefore, as shown in the upper part of FIG. 11, the first, second, fourth, fifth and eighth chips of symbol 1, and the second, third and sixth chips of symbol 2 Provides sufficient received power, and the third, sixth, and seventh chips of symbol 1 and the first, fourth, fifth, seventh, and eighth chips of symbol 2 are strongly attenuated. When the received power cannot be obtained, there will be times. At this time, in symbol 1, the symbol “1” is spread code C = [

8, 1

1 1 1 1 1 1 1 1], C = [1 -1 -1 1 1 -1 -1 1] spread signal

8, 7

The received signals are “1 1 0 1 1 0 0 1” and “1 1 0 1 1 0 0 1”, respectively. Multiplying the received signal including these two signals by spreading code C

8, 1

"5" and "3" are obtained.

[0014] Also, in symbol 2, similarly, the symbol "1" is set to the spread code C = [1 1 1 1 1

8, 1

1 1 1], C = [1 -1 -1 1 1 -1 -1 1] spread signal received signal

8, 7

Are “0 1 1 0 0 1 0 0” and “0 — 1 1 0 0 — 1 0 0”, respectively. When the received signal including these two signals is multiplied by the spreading code C, “3” and “

8, 1

—3 ”is obtained. Thus, when using a chip interleaver, inter-code interference M CI occurs, and enough received power is obtained in half of the chips! /, But symbols 1 and 2 cannot be demodulated correctly.

[0015] As described above, when code multiplexing using spreading codes and interleaving in units of chips are used in combination, even in a frequency selective fading environment with little frequency variation, frequency selective fading with a large frequency variation can be achieved. Since similar fluctuations occur in units of chips, it is possible to obtain a frequency diversity effect in units of chips. However, due to this fluctuation, there is a problem that the correlation between the code sequences of the spreading codes is broken on the receiving side, and it may not be possible to obtain symbols accurately from the code-multiplexed signal.

[0016] The present invention can obtain a symbol with high accuracy on the receiving side from a code-multiplexed signal while obtaining a frequency diversity effect by using code multiplexing by spreading code and interleaving in units of chips. It is an object to provide a transmission device, a reception device, a communication system, and a communication method.

Means for solving the problem

[0017] The present invention has been made to solve the above-described problem, and the transmission apparatus of the present invention spreads transmission symbols using a spreading code to generate a chip for each code channel. A group consisting of a code multiplexing unit that multiplexes the chips of a plurality of channels and generates a multiplexed signal, and a group of the multiplexed signals adjacent to each other in the spreading direction with a smaller number of chips than the spreading rate of the spreading code. And an interleaver for rearranging the order of the spreading direction of the multiplexed signal.

[0018] With this, the transmitting apparatus of the present invention transmits a signal capable of accurately obtaining a symbol on the receiving side from a code-multiplexed signal while obtaining a frequency diversity effect by using an appropriate spreading code and group. it can.

[0019] In the transmission apparatus of the present invention, it is preferable that the multiplexed signal can be separated by a spreading code corresponding to the group among the spreading codes.

Moreover, in the transmission apparatus of the present invention, it is preferable that the portion between the spreading codes corresponding to the group is orthogonal or quasi-orthogonal.

[0020] Thus, the transmitting apparatus of the present invention can transmit a signal that can accurately acquire symbols on the receiving side from a code-multiplexed signal while obtaining a frequency diversity effect. [0021] Further, in the transmitting apparatus of the present invention, the group is preferably within a unit of spreading processing by the spreading unit! /.

[0022] Further, in the transmission device of the present invention, it is preferable that the number of chips constituting each group is the same.

[0023] Further, in the transmission apparatus of the present invention, it is preferable to perform communication using the MC-CDMA system.

[0024] The receiving apparatus of the present invention receives a group of signals composed of signals adjacent to each other in the spreading direction of the spreading process having a smaller number of chips than the spreading rate of the spreading code used for the spreading process at the time of transmission. Corresponding to the spreading code by multiplying the spreading code by the Dinterleaver section that performs Dinterleaving by rearranging the order of the spreading direction of the signal and the received signal that is Dinterleaved by the Dinterleaver section. A despreading unit for separating and extracting symbols.

[0025] Thus, the receiving apparatus of the present invention can obtain a symphony with high accuracy from a code-multiplexed signal while obtaining a frequency diversity effect by using an appropriate spreading code and group.

In the receiving apparatus of the present invention, it is preferable that the correlation between the spreading codes of the part corresponding to the group is orthogonal or quasi-orthogonal.

[0027] Thereby, the receiving apparatus of the present invention can acquire a symbol with high accuracy from a code-multiplexed signal while obtaining a frequency diversity effect.

[0028] In the receiving apparatus of the present invention, it is preferable that the group is within the unit of the spreading process.

[0029] Further, in the receiving apparatus of the present invention, it is preferable that the number of chips constituting each group is the same.

[0030] Further, in the receiving apparatus of the present invention, it is preferable to perform communication using the MC-CDMA system.

[0031] The communication system of the present invention is a communication system including a transmission device and a reception device, wherein the transmission device spreads transmission symbols using a spreading code and generates a chip for each code channel. Multiplexer and multiple channels chip are multiplexed and multiplexed The order of the spreading direction of the multiplexed signal is rearranged in units of groups of the code multiplexing unit that generates the multiplexed signal and the multiplexed signal adjacent in the spreading direction with a smaller number of chips than the spreading rate of the spreading code. An interleaver unit, and the reception apparatus rearranges the order of the spreading direction of the received signal in units of the group so that the rearrangement by the interleaver unit is restored. And a despreading unit that separates and extracts symbols corresponding to the spreading code by multiplying the received signal that has been deinterleaved by the dingerleaver unit by the spreading code. To do.

[0032] The communication method of the present invention is a communication method in a communication system composed of a transmission device and a reception device, wherein the transmission device spreads transmission symbols using a spreading code for each channel to generate a chip. The first process, the second process in which the transmitter multiplexes the chips of the plurality of channels generated in the first process and generates a multiplexed signal, and the transmitter in the spreading direction. A third step of rearranging the order of the spread direction of the multiplexed signal in units of groups of adjacent multiplexed signals; and the order of the spread direction of the received signals by the receiving device in units of the groups. And a received signal that has been deinterleaved in the fourth step by the receiver, and a fourth step in which the receiver is rearranged so that the rearrangement in the third step is restored. In the by multiplying the spreading code comprises a fifth step of extracting separation symbols channel corresponding to the spreading code.

The invention's effect

[0033] According to the present invention, since the influence of propagation path fluctuation in the spreading direction is affected in units of groups, a code-multiplexed signal can be obtained while obtaining a frequency diversity effect by using an appropriate spreading code and group. Therefore, the symbol can be acquired with high accuracy on the receiving side. Brief Description of Drawings

FIG. 1 is a schematic block diagram showing a configuration of a transmission device according to a first embodiment of the present invention.

Yes

FIG. 2 is a diagram showing an example of interleaving by grouping a plurality of chips by an interleaver unit 7 according to the first embodiment. 3] This is a diagram showing an example of a received signal when there is a frequency variation when the interleaver grouped by the interleaver unit 7 is used.

4] A schematic block diagram showing the configuration of the receiving apparatus according to the first embodiment.

5] A schematic block diagram showing the configuration of the receiving device according to the second embodiment.

FIG. 6 is a schematic block diagram showing a configuration of an MCI replica generation unit 27 in the same embodiment. FIG. 6 is a diagram showing an example of a received signal when frequency axis spreading and code multiplexing are performed. 8] FIG. 8 is a diagram showing a despreading process for the received signal example shown in FIG.

9] It is a diagram showing a despreading process for an example of a received signal that has undergone frequency fluctuation. Fig. 10 is a diagram showing an example of the received signal when there is a frequency fluctuation when the symbol interleaver is used.

11] It is a figure showing an example of the received signal when there is a frequency fluctuation when using a chip interleaver.

Explanation of symbols

1 1 1 Cn code channel signal generator

2 Error correction encoder

3 Modulator

4 17 Series-parallel converter

5 Diffusion part

6 Code multiplexer

7 Interleaver section

8 IFFT Department

9 22 Parallel to serial converter

10 Pilot multiplexing part

11 GI Club

12 Transmission finalizer

13 Pilot signal generator

14 Transmitting antenna 15 Receiving antenna

16 GI removal unit

18 FFT section

19, 32 Propagation path compensation section

20 Dinterleaver

21--1 to 21— Cn back diffusion

23 Demodulator

24, 33 Decryption unit

25 Propagation path estimation unit

26--1 ~ 26 -Cn, 31-l ~ 31 -Cn

27 Symbol replica generator

28--1 to 28 -Cn Code channel replica 'Signal generator 1

29 MCI replica generator

30--;! ~ 30— N adder

36 Transfer function multiplier

42 D / A converter

43 Radio section

52 Radio section

53 A / D converter

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiment, the power to be described in the case of MC-CDMA system using frequency axis spreading for multi-carrier transmission! / Is applied to the present invention is limited to frequency axis spreading. It can be used even in the case of spreading in the time axis, or in the case of spreading in two dimensions, the frequency axis and the time axis. Further, the present invention can be used even in the case of single carrier transmission, which is not limited to application to multicarrier transmission.

[0037] [First embodiment]

In the first embodiment, an interleaver that focuses on the orthogonality cycle of the spreading code is used. A wireless transceiver is described. FIG. 1 is a schematic block diagram showing the configuration of the transmission apparatus according to the first embodiment. The transmitter is a code channel signal generator 1;! ~ 1 Cn, code multiplexer 6, interleaver 7, IFFT (Inverse Fast Fourier Transformation) 8, parallel / serial converter 9, pilot It consists of a multiplexing unit 10, a GI (Guard Interval) insertion unit 11, a D / A conversion unit 42, a transmission filter unit 12, a radio unit 43, and a transmission antenna unit 14.

Where Cn is the number of multiplexed codes.

[0038] The code channel signal generation unit 1 1 to 1 Cn includes an error correction coding unit 2 that performs error correction coding such as a turbo code and a convolutional code on information bits, and QPSK ( Quadrature Phase Shift Keying), 16Q AM (Quadrature Amplitude Modulation), etc. It consists of a spreading unit 5 that generates chips by multiplying and spreading spreading code sequences.

[0039] The code multiplexing unit 6 multiplexes signals output from the code channel signal generation units 11 to 1 Cn to generate a multiplexed signal. The interleaver unit 7 rearranges the multiplexed signals in the frequency direction while suppressing inter-code interference (MCI) and performs chip interleaving. The IFFT unit 8 performs frequency time conversion on the chip interleaved signal. The parallel / serial converter 9 performs parallel / serial conversion on the frequency-time converted signal. The pilot multiplexing unit 10 time-multiplexes the pilot signal generated by the pilot signal generation unit 13. The GI insertion unit 11 inputs a guard interval GI. The D / A converter 42 generates a transmission signal by D / A converting the signal inserted with the guard interval GI. The transmission filter unit 12 performs waveform shaping of the transmission signal. The radio unit 43 converts the transmission signal into a radio frequency. The transmission antenna unit 14 transmits a transmission signal converted into a radio frequency.

[0040] Next, the interleaving performed by the interleaver unit 7 will be described, in which a plurality of chips in a spreading unit are grooved and the interleaving in units of groups is described. As a result, it is possible to obtain the frequency diversity effect due to interleaving while enabling code separation by suppressing the occurrence of inter-code interference MCI. Figure 2 shows the As an example of interleaving, an example is shown in which chips that have been spread in the frequency axis with a spreading factor of “8” are grouped every two chips and rearranged in the subcarrier direction. In Fig. 2, the number of subcarriers is N, and the darno rape is performed every two chips from the chip assigned to the first subcarrier, one group of chip N-1 and chip N). Interleaving is then performed by rearranging the groups in the frequency direction. The interleaver unit 7 stores a rearrangement destination position for each chip in advance, and arranges each input chip at the stored rearrangement destination position. That is, the interleaver part

7 is a group of signals adjacent to each other in the spreading direction (here, frequency axis direction) of the number of chips (here, 2) within the spreading unit and less than the spreading factor (here, “8”). Interleaving is performed by rearranging the order of the spreading direction (here, the frequency axis direction) in units of units.

[0041] The effect of the grouped interleaver will be described with reference to FIG. The upper part of Fig. 3 shows a frequency-selective fading environment with frequency fluctuations in the coordinate plane with the horizontal axis representing frequency and the vertical axis representing received power when a grooving interleaver (interleaver unit 7) is used. The figure shows the received power frequency characteristics of the received signal that has passed through the propagation path below, with the Dinterleave operation performed on the receiving side. For convenience of explanation, the received signal indicates 16 chips corresponding to 2 symbols on the frequency axis. Since the interleaver unit 7 performs rearrangement in units of two adjacent chips, the interleaver unit 7 is arranged in a different frequency region for each group due to rearrangement. Therefore, the interleaver unit 7 is affected by frequency fluctuations. The received power tends to be different for each group.

[0042] Therefore, as shown in the upper part of Fig. 3, the 1st, 2nd, 5th and 6th chips of symbol 1 and the 3rd, 4th, 5th and 6th chips of symbol 2 are Power that provides enough received power The third, fourth, seventh, and eighth chips of Simponole 1 and the first, second, seventh, and eighth chips of Simponole 2 are strongly attenuated. It may happen that the received power cannot be obtained. At this time, in symbol 1, the symbol “1” is spread code C = [1

8, 1

1 1 1 1 1 1 1], C = [1-1-1 1 1-1-1 1]

8, 7

The received signals are “1 1 0 0 1 1 0 0” and “1 1 0 0 1 —1 0 0”, respectively. Become. Multiplying the received signal including these two signals by spreading code C

8, 1

“4” and “0” are obtained.

[0043] Also, in symbol 2, similarly, the symbol "1" is spread code C = [1 1 1 1 1

8, 1

1 1 1], C = [1 -1 -1 1 1 -1 -1 1]

8, 7

Are “0 0 1 1 1 1 0 0” and “0 0 —1 1 1 1 0 0”, respectively. When the received signal including these two signals is multiplied by the spreading code C, “4” and “0” respectively.

8, 1

Is obtained. In this way, both symbols 1 and 2 can be correctly demodulated even though the number of chips with sufficient received power is half of the total.

[0044] As described above, the grouped interleaver performed by the interleaver unit 7 varies within the spreading unit as in the case of the chip interleaver, but no inter-code interference MCI occurs even when despreading is performed. This is because C binding force ¾ orthogonality is maintained for each chip. this

8, 1 8, 7

An interleaver grouped in this way has the effect of eliminating the reception quality difference for each symbol, which is a problem with symbol interleaving, and suppressing the disruption of orthogonality, which is a problem with chip interleaving.

[0045] The interleaving method performed by the interleaver unit 7 includes, for example, rearrangement at random, ERA, and erformance Comparison of Cnannel Interleaving Methods in Frequency Domain for VSF-OFCDM Broadband Wireless Access in Forwar d Link (N Maeda, H. Atarashi, M. Sawahashi, IEICE trans. Commun., Vol. E86-B) may be used, and the interleaving method and block interleaving may be used. Anything can be used if done. The chip grouping method uses, for example, an orthogonal code such as a Hadamard code, so the spreading factor is 2 ^k (k is an integer of 1 or more). , 2 chips, 4 chips,... If not even, the number of chips in each group should be a power of two. For example, if the spreading factor is 8, you may group every 4 chips so that the number of chips is equal! /, And the 8 chips that are the unit of the result of the spreading process will be divided into two 2-chip groups. It may be grouped into a group of 4 chips. That is, when orthogonal codes are used, the chips corresponding to each group in the spread code are The arrangement of the spreading code used in spreading section 5 and the group for interleaving in interleaver section 7 may be selected so as to be orthogonal between the spreading codes in the range.

[0046] In addition, when a code other than an orthogonal code, such as an M sequence or a Gold sequence, is used as a spreading code, the spreading factor is generally not a power of 2, and therefore it cannot be divided into groups with an equal number of chips. The grouping may be performed with the number of chips having a low correlation. In other words, the spreading code used in spreading section 5 and the group arrangement when interleaving in interleaver section 7 are selected so that the correlation between spreading codes in the range of chips corresponding to each group becomes low among the spreading codes. Please! /

FIG. 4 is a schematic block diagram illustrating a configuration of the receiving device according to the first embodiment. The receiving apparatus includes a receiving antenna unit 15, a radio unit 52, an A / D conversion unit 53, a GI removal unit 16, a series-parallel conversion unit 17, an FFT (Fast Fourier Transformation) unit 18, a propagation path compensation unit 19, and a dintarreever unit 20. .., 26-Cn, and propagation path estimation unit 25. The despreading unit 21, parallel-serial conversion unit 22, demodulating unit 23, decoding unit 24, and code separation unit 26-;!-26-Cn are also included.

[0048] The radio unit 52 converts the signal received by the receiving antenna unit 15 from a radio frequency into a baseband signal (hereinafter referred to as a received signal). The A / D conversion unit 53 generates a digital signal obtained by A / D converting the received signal and inputs the digital signal to the GI removal unit 16. The GI removal unit 16 removes the guard interval from the input digital signal, and the serial / parallel conversion unit 17 performs serial / parallel conversion on the signal from which the guard interval has been removed. The FFT unit 18 performs time-frequency conversion on the serial / parallel converted signal and inputs the signal to the propagation path compensation unit 19. The propagation path compensation unit 19 suppresses frequency fluctuations based on the propagation path estimated by the propagation path estimation unit 25. The propagation path estimation performed by the propagation path estimation unit 25 is performed by using, for example, an RLS (Recursive Least Square) algorithm using a pilot signal. Let H (n) be the transfer function of the nth subcarrier in the propagation path estimated by the propagation path estimator 25. The average noise power and sigma ^2. At this time, the MMSE weight W (n) used in the propagation path compensation unit 19 is, for example, as shown in the following equation (1). Where * represents the complex conjugate and H * (n) represents the complex conjugate of H (n).

[0049] [Equation 3] ^r (n) ― '-: ".'. ... · γ ~ (1)

-E X H (η) χ Η (n) ^ <3 „

[0050] If the frequency signal in the n-th subcarrier input to the propagation path compensation unit 19 is R (n), the propagation path compensation unit 19 uses W (n) in Equation (1) to Calculate and output S (n) expressed by equation (2).

[0051] [Equation 4]

S (n) ~ W (n) x Ri'n) (2)

[0052] The output S (n) of the propagation path compensator 19 is processed by the Dinterleaver unit 20 by performing a reverse process to that performed by the interleaver unit 7 on the transmission side and performing interleaving. Dinter leave by returning to the order in which it was before. From the Dinterleaved signal, the code separation unit 26— ;! to 26—Cn obtains information bits in each code channel. In code separation unit 26— ;! to 26—Cn, despreading unit 21— ;! to 21—Cn performs despreading by multiplying the deinterleaved signal by a spreading code corresponding to each code channel. The parallel-to-serial converter 22 performs parallel-to-serial conversion on the despread signal, the demodulator 23 calculates a bit LLR (Log Likelihood Ratio) from the despread signal, and the decoder 24 makes an error with respect to the bit LLR. A correction decoding process is performed, and the obtained information bits are output. The processing of the demodulator 23 is performed later.

[Second Embodiment]

In the second embodiment, a repetitive parallel MCI canceller is used on the receiving side. The repetitive MCI canceller generates MCI replicas on the receiving side and subtracts it from the received signal to suppress inter-code interference MCI. By combining with the interleave described in the first embodiment, The effect of MCI suppression is improved. This will be explained below. Note that the processing on the transmission side is the same as that described in the first embodiment with reference to FIG.

FIG. 5 shows the configuration of the receiving device in the second embodiment. The receiving device includes a receiving antenna unit 15, a radio unit 52, an A / D conversion unit 53, a GI removal unit 16, a serial-parallel conversion unit 17, an FFT unit 18, a code separation unit 31—l—31-Cn, and a code channel replica signal. Generator 28—;! ~ 28— C n, MCI replica generation unit 29, and propagation path estimation unit 25. Code separation unit 31— ;! to 3 1— Cn is added to addition unit 30— ;! to 30—N, propagation path compensation unit 32, Dinter river unit 20, and despreading unit 21— ;! 21—Consists of a Cn code whose second half coincides with the code separation unit, a parallel-serial conversion unit 22, a demodulation unit 23, and a decoding unit 33. N is the number of subcarriers. The code channel replica signal generation unit 28— ;! to 28—Cn includes a symbol replica generation unit 27, a serial-parallel conversion unit 4, and a spreading unit 5, respectively.

[0055] The radio unit 52 converts the signal received by the receiving antenna unit 15 from a radio frequency into a baseband signal (hereinafter referred to as a received signal). The A / D conversion unit 53 generates a digital signal obtained by A / D converting the received signal and inputs the digital signal to the GI removal unit 16. The GI removal unit 16 removes the guard interval from the input digital signal, and the serial / parallel conversion unit 17 performs serial / parallel conversion on the signal from which the guard interval has been removed. The FFT unit 18 performs time-frequency conversion on the serial / parallel converted signal, and inputs the conversion result to the code separation unit 31— ;! to 31—Cn. Code separation unit 31— ;! to 31— Cn subtracts the MCI replica generated by the MCI replica generation unit 29 in the addition units 30-1 to 30-N from the input signal, thereby inter-code interference. Suppress MCI. Thereafter, the channel compensation unit 32 suppresses the frequency fluctuation. The MMSE weight Wc (n) when the MCI canceller is applied uses, for example, the following equation (3) using the estimated transfer function H (n).

[0056] [Equation 5]

However, σ ² is the mean square error between the received signal and the replica of the received signal. However, Equation (1) is used for the initial processing that cannot generate a replica. If the received signal after subtraction of the MCI replica, that is, the output of the adder 30—η is Rc (n), the propagation path compensator 32 calculates Sc (n) represented by the following equation (4) and outputs it. To do.

[0058] [Equation 6] Sc {n) ― Wc (n} x Rc (n)

[0059] The Dinterleaver unit 20 performs Dinterleave on the output Sc (n) of the propagation path compensation unit 32. As described in the first embodiment, the processing in the Dinterleaver unit 20 performs reverse processing of interleaving that groups a plurality of chips performed on the transmission side.

After deinterleaving, the despreading unit 21— ;! to 21—Cn performs despreading by multiplying the corresponding spreading code. The despread signal is parallel-serial converted by the parallel-serial converter 22, the bit LLR is obtained by the demodulator 23, and error correction decoding processing is performed by the decoder 33 to obtain information bits and encoded bits LLR . If no error is detected in the information bits, or if the number of repetitions is less than the specified number of repetitions, processing is repeated. For error detection of information bits, for example, a CRC (Cyclic Redundancy Check) is added to the information bits on the transmission side and received.

Four

If error detection is performed on the trust side,

[0061] The processing of the demodulation unit 23 will be described. The spreading factor is SF, and the signal from the first to the SF chips deinterleaved by the Dinterleaver unit 20 is the despreading unit 21 — ;! ~ Cn is the despread signal. At this time, S ′ can be expressed by the following equation (5).

[0062] [Equation 7]

5 '= μ5 + (5)

[0063] However, S is a transmission signal corresponding to S ', 11 is an equivalent amplitude, η is an error signal with an average of 0 and variance, and the equalized amplitude is expressed by the following equation (6) as the variance of the error signal V ² is the following formula (7).

[0064] [Equation 8 μ μ = ■ ■ w (n) H (n) c β)

n-i

v ² -μ ~ ² ί 7)

However, for w (n) in equation (6), W (n) in equation (1) is used in the initial processing, and Wc (n) in equation (3) is used in the iterative processing. Here, the case of QPSK modulation is shown as an example where the demodulator 23 obtains the bit log likelihood ratio using the equivalent amplitude from S ′. Bit when S 'is sent B and b (b and b are 1 or 1), the bit sequences b and b are QPSK modulated.

0 1 0 1 0 1 The transmission signal S can be expressed as in equation (8).

[0066] [Equation 9]

1

, ^! 2

[0067] where j represents an imaginary unit. From this, λ (b), which is the bit LLR of b, is given by equation (9).

0 1 0

[0068] [Equation 10] (9)

[0069] Also, the bit LLR of b can be replaced by the real part and the imaginary part of equation (9)! /. Where Re (x) represents the real part of the complex number X.

[0070] Next, repeated processing will be described. In the iterative process, the coded bit LLR with the updated likelihood is output from the decoding unit 33 and input to the code channel replica signal generation unit 28— ;! to 28—Cn. Code channel replica signal generator 28—;! To 28— In Cn, a symbol replica generator 27 generates a replica signal of a modulation symbol from the coded bit LLR. After that, the serial-parallel converter 4 performs serial-parallel conversion on this replica signal, and the spreading unit 5 spreads the replica signal subjected to serial-parallel conversion with a spreading code corresponding to each code channel, thereby transmitting the transmission signal in each code channel. A replica is generated and input to the MCI replica generation unit 29. The MCI replica generation unit 29 generates a replica of the inter-code interference MCI using the input transmission signal replica in each code channel and the channel estimation value output from the channel estimation unit 25.

The processing of the symbol replica generation unit 27 will be described here in the case of QPSK. It is assumed that the bit LLRs constituting the symbol replica S ′ are (b) and (b).

r 2 0 2 1

However, 0 is the output of the decoding unit 33. The symbol replica generation unit 27 calculates S,

2 r

).

[0072] [Equation 11] Si-) / 2j MO)

■ '

FIG. 6 shows details of the MCI replica generation unit 29. FIG. 6 is a schematic block diagram of the MCI replica generation unit 29 in the k-th code channel. The MCI replica generation unit 29 includes a code multiplexing unit 34, an interleaver unit 7, and a transfer function multiplication unit 36.

In order to generate an MCI replica in the k-th code channel, the code multiplexing unit 34 multiplexes replica signals other than the replica signal of the k-th code channel. That is, 1,..., K−l, k + 1,..., Cn-th code channel replica signal is multiplexed. After that, the multiplexed replica signal is interleaved by the interleaver unit 7 in the same manner as on the transmission side, and the transfer function multiplication unit 36 transmits the transfer function H (n (n) estimated by the propagation path estimation unit 25 in FIG. ) Is multiplied by the interleaved replica signal to generate an MCI replica frequency signal. The transfer function multiplication unit 36 inputs these frequency signals to the code separation unit 31— ;! to 31—C n, and thereafter, the code separation unit 31— ;! to 31—Cn addition unit 30— ;! -30-N subtracts MCI replica from received signal in frequency domain to suppress inter-code interference MCI, propagation path compensation unit 32 suppresses frequency fluctuation, decoding unit 33 specifies error correction decoding process Repeat until the number of repeats or no error is detected.

In the second embodiment, the MCI replica is generated by the frequency signal and the inter-code interference MCI removal is performed in the frequency domain. However, the MCI replica is generated by the time signal and is transmitted to the GI removal unit 16 in the time domain. Inter-code interference MCI cancellation may be performed.

[0075] It should be noted that the code channel signal generation unit 1 1 to 1 Cn, the code multiplexing unit 6, the interleaver unit 7, the IFFT unit 8, the parallel-serial conversion unit 9, the pilot multiplexing unit 10, the GI insertion unit 11, FIG. In addition, the GI removal unit 16, the serial-parallel conversion unit 17, the FFT unit 18, the propagation path compensation unit 19, the Dinter Reveal unit 20, the propagation path estimation unit 25, the code separation unit 26—;! To 26—Cn, FIG. In addition, the GI removal unit 16, the serial-parallel conversion unit 17, the FFT unit 18, the code separation unit 31— ;! to 31—Cn, the code channel replica signal generation unit 28— ;! to 28—Cn, and the MCI replica in FIG. The generation unit 29 and the propagation path estimation unit 25 may be realized by dedicated hardware. Each of these units is configured by a memory and a CPU (central processing unit) to realize the function of each unit. This function may be realized by the CPU executing the program for this purpose. As described above, 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 a design and the like within a scope not departing from the gist of the present invention. .

Industrial applicability

[0077] The present invention is not limited to this force that is suitable for use in a mobile phone and a base station apparatus that communicate in a multi-carrier transmission scheme.

Claims

The scope of the claims

[1] Spreading transmission symbols using spreading codes to generate chips for each code channel;

The multiplexing is performed in units of a group consisting of a code multiplexing unit that multiplexes the chips of a plurality of channels and generates a multiplexed signal, and the multiplexed signals that are adjacent in the spreading direction with the number of chips smaller than the spreading rate of the spreading code. Rearrange the order of the spread direction of the signal

A transmission apparatus comprising:

[2] The transmission apparatus according to [1], wherein the multiplexed signal can be separated by a spreading code corresponding to the group among the spreading codes.

[3] The transmission apparatus according to [1], wherein among the spreading codes, a portion of the spreading code corresponding to the group is orthogonal or quasi-orthogonal.

4. The transmission device according to claim 1, wherein the group is within a unit of diffusion processing by the diffusion unit.

[5] The transmission device according to [1], wherein the number of chips constituting each group is the same.

[6] The transmitter according to claim 1, which performs communication using MC—CDMA.

[7] The order of the spreading direction of the received signal is rearranged in units of groups that also have signal power adjacent to the spreading direction of the spreading process with the number of chips smaller than the spreading rate of the spreading code used for spreading. The Dinter Leaver part to Dint Reeve,

A despreading unit that separates and extracts a symbol of a channel corresponding to the spreading code by multiplying the spread code by the received signal that has been deinterleaved by the Dinterleaver unit;

A receiving apparatus comprising:

[8] The receiving apparatus according to [7], wherein a part of the spreading code corresponding to the group is orthogonal or quasi-orthogonal.

9. The receiving device according to claim 7, wherein the group is within a unit of the spreading process.

10. The receiving device according to claim 7, wherein the number of chips constituting each group is the same. Place

[11] The receiving device according to claim 7, wherein communication is performed using MC—CDMA.

[12] In a communication system consisting of a transmission device and a reception device,

The transmitter is

A spreading unit for each channel that spreads transmission symbols using a spreading code and generates chips for each code channel;

Comprising

The receiving device is:

Deinterleaving in which the group is deinterleaved by rearranging the order of the spreading direction of the received signal in such a way that the rearrangement by the interleaver unit is restored.

A despreading unit that separates and extracts a symbol corresponding to the spreading code by multiplying the spread code by the received signal that has been deinterleaved by the Dinterleaver unit.

A communication system characterized by the above.

[13] In a communication method in a communication system including a transmission device and a reception device,

A first process in which the transmitting device spreads transmission symbols using a spreading code for each channel to generate a chip; and

A second process in which the transmitting device multiplexes the chips of the plurality of channels generated in the first process and generates a multiplexed signal;

A third process in which the transmitting apparatus rearranges the order of the multiplexed direction of the multiplexed signal in units of groups of the multiplexed signals adjacent in the spreading direction;

The receiving apparatus performs a Dinterleave by rearranging the order of the spreading direction of the received signals in units of the groups so that the rearrangement by the third process is restored. And the fourth process

A fifth process in which the receiving device separates and extracts a symbol of a channel corresponding to the spreading code by multiplying the spread signal by the spreading code to the received signal deinterleaved in the fourth process;

A communication method comprising: