JP2002204217A - Spread code allocating method, signal transmitting method, signal receiving method, transmitting device, receiving device, and recording medium of mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently use a spread code for a downlink of a mobile communication system using a multi-carrier CDMA system. SOLUTION: An information symbol is multiplied by a short code and further multiplied by a long code. An information symbol series is copied as many times as symbols equal to the series length of the short code by information symbols and arranged on a frequency axis. Then the arranged information symbol series on the frequency axis is multiplied by the short code. Further, the information symbol series on the frequency axis multiplied by the series length N is multiplied by the long code.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a multi-carrier C
The present invention relates to a spreading code assignment method, a signal transmission method, a signal reception method, a transmission device, a reception device, and a recording medium in a DMA mobile communication system.

[0002]

2. Description of the Related Art Conventionally, by identifying each communication person using a spreading code assigned to each communication person, a plurality of communication persons perform communication using the same frequency band. A CDMA system is known. IMT-2
In the next-generation mobile communication system called 000, a wideband direct spread (DS) -CDMA system (hereinafter, “W-CDMA system”) having a spreading band of 5 MHz or more is used as a wireless access system.
Has been adopted.

In the W-CDMA downlink,
Each communication party is identified using a short code, which is a spreading code assigned to each communication party in the wireless base station and has the same repetition cycle as the information symbol cycle. On the other hand, the radio mobile station identifies each radio base station by using a long code whose repetition cycle is much longer than a short code.

FIG. 1 is a diagram for explaining a conventional spreading code assignment method in a downlink of an asynchronous system between base stations and a synchronous system between base stations. W-CDM
The A system adopts an asynchronous system between base stations which does not require an external system for time synchronization, as shown in FIG.
4, different long codes # 0, # 1 and # 2 are used for each radio base station in order to identify the radio base stations that cover 4, 106 and 108, respectively. Note that the long code is also called a scramble code in the sense that a signal from another cell is converted into noise.

On the other hand, similar to the W-CDMA system, the IMT-
Cdma200 proposed in the US as a candidate for 2000
The system 0 or the conventional IS-95 realizes a synchronization system between base stations as shown in FIG.
Long code layer 1 by using S116 etc.
In 02, the radio base stations 110, 112 and 114 all have a common time reference. In this system,
The radio base station is identified using the same type of long code provided with different timing shifts # 0 ', # 1', and # 2 '.

[0006] As a radio access system of a mobile communication system after IMT-2000, multicarrier D
Methods for transmitting signals using multicarriers, such as the S-CDMA system and the multicarrier CDMA system, are being studied. Here, the multicarrier CDMA system is a transmission system in which copied information symbols are arranged on a frequency axis, multiplied by a spreading code on the frequency axis, and a signal is transmitted using a plurality of subcarriers. It is. In the multi-carrier CDMA system, a plurality of communicators are simultaneously communicating using the same frequency band.

[0007]

However, studies on the multi-carrier CDMA system up to now have focused on performance evaluation at the link level and studies on timing and frequency synchronization. Multi-carrier CDM
In the A system, the conventional D code is used to identify a communication party using a spreading code assigned to each communication party.
Despite being similar to the S-CDMA system, no study has been made on an efficient method of allocating spreading codes.

[0008] Further, when the multi-carrier CDMA system is used for a mobile communication system, it has not been studied, although it is necessary to identify a radio base station, as in the W-CDMA system. There was a problem.

The present invention has been made in view of such a problem, and an object of the present invention is to use a spreading code efficiently when a multicarrier CDMA system is adopted as a mobile communication system. It is an object of the present invention to provide a spreading code allocation method, a signal transmission method, a signal reception method, a transmission device, a reception device, and a recording medium in a mobile communication system capable of performing the above.

[0010]

In order to solve the above-mentioned problems, the present invention provides a radio base station which duplicates each information symbol of an information symbol sequence to be transmitted, arranges the duplicated information symbols on a frequency axis, Spreading code allocation in a mobile communication system for transmitting a signal by multiplying a spread code by a duplicated information symbol arranged on an axis and transmitting the information symbol sequence multiplied by the spreading code using a plurality of subcarriers Assigning a short code, which has a repetition period equal to the number of duplicated information symbols and is used to identify a mobile station, to all radio base stations in common, Have one or more long codes that have a repetition period longer than the number of copies of the base station, and are used to identify each base station. Providing a spreading code allocation method in a mobile communication system, comprising the steps of: assigning individually to each.

Further, the present invention relates to a method for transmitting a signal from a radio base station in a mobile communication system, comprising: (a) duplicating each information symbol of an information symbol sequence to be transmitted and placing the duplicated information symbol on a frequency axis; Arranging steps,
(B) For the duplicated information symbols arranged on the frequency axis, a short code having a repetition period equal to the number of duplicated information symbols and a long code having a repetition period longer than the number of duplicated information symbols. Multiplying a spreading code including a code to obtain a spreading information symbol sequence obtained by doubly spreading the information symbol sequence; and (c) transmitting the spreading information symbol sequence using a plurality of subcarriers. And a signal transmission method characterized by having:

In the present invention, the step (b)
Is one of a group of short codes used to identify a mobile station and commonly assigned to all wireless base stations, and individually assigned to each of the wireless base stations used to identify each base station. Multiplying one of the obtained one or more long codes.

In the present invention, the long code has a sequence length longer than the number of subcarriers, and the step (b) comprises multiplying the short code by a sequence length equal to the number of subcarriers. And obtaining a spread information symbol sequence by obtaining a short code multiplied information symbol sequence to be transmitted simultaneously and multiplying the short code multiplied information symbol sequence into a plurality of short code multiplied information symbol sequences by a long code.

In the present invention, the long code has a sequence length equal to the number of the subcarriers, and the step (b) comprises multiplying the short code by a sequence length equal to the number of the subcarriers. A short code multiplied by the short code multiplied information symbol sequence immediately before by obtaining a short code multiplied information symbol sequence to be transmitted simultaneously and multiplying each of the different short code multiplied information symbol sequences on the time axis by a long code , The spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code while sequentially shifting the information symbol sequence by one or more information symbols in the frequency direction.

Further, the present invention relates to a method for receiving a signal in a mobile station in a mobile communication system, comprising: (a) receiving a spread information symbol sequence transmitted from a radio base station using a plurality of subcarriers; (B) multiplying the spread information symbol sequence by a long code and a spread code including a short code having a shorter sequence length than the long code, and generating a number of spread code multiplied information symbols equal to the sequence length of the short code And obtaining a despread information symbol sequence obtained by doubly despreading the spread information symbol sequence.

Also, in the present invention, the step (b)
Is one of a group of short codes used to identify a mobile station and commonly assigned to all wireless base stations, and individually assigned to each of the wireless base stations used to identify each base station. Multiplying one of the obtained one or more long codes.

Further, the present invention relates to a transmitting apparatus for transmitting a signal from a radio base station in a mobile communication system,
Duplicate each information symbol of the information symbol sequence to be transmitted,
A replication unit for arranging the replicated information symbols on the frequency axis;
For the duplicated information symbols arranged on the frequency axis,
The information symbol sequence is multiplied by a spreading code including a short code having a repetition period equal to the number of duplicated information symbols and a long code having a repetition period longer than the number of duplicated information symbols. A transmission device comprising: a spreading unit that obtains a spread information symbol sequence that has been heavily spread, and a transmission unit that transmits the spread information symbol sequence using a plurality of subcarriers.

Further, in the present invention, the spreading section is used to identify each base station from one of a group of short codes that are used to identify a mobile station and are commonly assigned to all radio base stations. And one of one or more long codes individually assigned to each of the radio base stations.

Further, in the present invention, the long code has a sequence length longer than the number of subcarriers, and the spreading section has a sequence length equal to the number of subcarriers by multiplying by a short code. Then, a short code multiplied information symbol sequence to be transmitted at the same time is obtained, and the spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code.

Further, in the present invention, the long code has a sequence length equal to the number of the subcarriers, and the spreading section multiplies the short code to have a sequence length equal to the number of the subcarriers. The short code multiplied information symbol sequence to be transmitted at the same time is obtained, and the short code multiplied information symbol sequence on the time axis is multiplied by the long code multiplied by each of the different short code multiplied information symbol sequences. The spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code while sequentially shifting one or a plurality of information symbols in the direction.

Further, the present invention relates to a receiving apparatus for receiving a signal at a mobile station in a mobile communication system, wherein the receiving section receives a spread information symbol sequence transmitted from a radio base station using a plurality of subcarriers. Multiplying the spread information symbol sequence by a long code and a spread code including a short code having a shorter sequence length than the long code, and synthesizing a number of spread code multiplied information symbols equal to the sequence length of the short code. And a despreading unit for obtaining a despread information symbol sequence obtained by doubly despreading the spread information symbol sequence.

In the present invention, the despreading unit identifies each base station from one of a short code group used for identifying a mobile station and commonly assigned to all radio base stations. And multiplying each of the radio base stations by one of one or more long codes individually allocated thereto.

Further, the present invention is a recording medium on which a computer program code for causing a computer to function as a transmitting device for transmitting a signal from a radio base station in a mobile communication system is recorded. One information symbol is duplicated for each of the information symbols of the information symbol sequence to be duplicated and the first computer program code for arranging the duplicated information symbols on the frequency axis and the duplicated information symbol arranged for the frequency axis. Spreading information obtained by multiplying a short code having a repetition period equal to the set number by a spreading code including a long code having a repetition period longer than the number of copies of one information symbol to double-spread the information symbol sequence A second computer program code for finding a symbol sequence If, to provide a recording medium characterized by having a third computer program code to be transmitted by using a plurality of sub-carrier the spread information symbol sequence.

Also, in the present invention, the second computer program code is used for identifying a mobile station, and is one of a short code group commonly assigned to all radio base stations, and each base station. And multiplying by one of one or more long codes individually assigned to each of the radio base stations.

In the present invention, the long code has a sequence length longer than the number of the subcarriers, and the second computer program code is equal to the number of the subcarriers by multiplying the short code. A short code multiplied information symbol sequence having a sequence length and transmitted at the same time is obtained, and the spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code. .

In the present invention, the long code has a sequence length equal to the number of subcarriers, and the second computer program code is equal to the number of subcarriers by multiplying by a short code. A short code multiplied information symbol sequence having a sequence length and transmitted at the same time was obtained, and the previous short code multiplied information symbol sequence was multiplied by a long code multiplied by each of the different short code multiplied information symbol sequences on the time axis. The spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code while sequentially shifting one or more information symbols in the frequency direction from the long code.

Further, the present invention is a recording medium recording a computer program code for causing a computer to function as a receiving device for receiving a signal at a mobile station in a mobile communication system, wherein the computer program code is transmitted from a radio base station. A first computer program code for receiving a spread information symbol sequence transmitted using a plurality of subcarriers, and a long code for the spread information symbol sequence, including a short code having a shorter sequence length than the long code. A second computer program for multiplying a spreading code and synthesizing a number of spread code multiplied information symbols equal to the short code sequence length to obtain a despread information symbol sequence obtained by double despreading the spread information symbol sequence And a recording medium characterized by having a code

Further, in the present invention, the second computer program code is used for identifying a mobile station, and one of a short code group commonly assigned to all the radio base stations and each base station. And multiplying by one of one or more long codes individually assigned to each of the radio base stations.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, a “short code” is a code having a repetition period equal to the number of duplicated information symbols, and a “long code” is compared with the number of duplicated information symbols. The code has a long repetition cycle.

In the present embodiment, the information symbol sequence transmitted by the radio base station includes one of a short-period spreading code (short code) group and one or more long-period spreading codes assigned to each radio base station. One of the codes (long codes) is multiplied.

FIG. 2 is a diagram for explaining an example of a spreading code assignment method in the multicarrier CDMA mobile communication system according to the present embodiment.

In the example shown in FIG. 2A, a set of short codes for identifying a communicating party (mobile station) in the short code layer 201 is a combination of the radio base stations 204 and 20.
6 and 208 use a common one.

In the long code layer 200, different long codes for identifying the radio base stations are assigned to different radio base stations, one for each radio base station. 206
, And a long code # 2 for the radio cell 208.

In the example shown in FIG. 2B, a set of short codes for identifying a communicating party (mobile station) in the short code layer 203 is set for all the radio base stations 21.
0, 212 and 214 use common ones. In the long code layer 202, two different long codes for identifying the radio base stations are assigned to each radio base station.
10, long codes # 0 and # 1 are assigned to the wireless cell 212, and long codes # 4 and # 5 are assigned to the wireless cell 214.

As described above, in the mobile communication system using the multi-carrier CDMA system, by assigning different long codes to each base station, a short code group common to the base stations can be used, and the spreading code can be used. It can be used efficiently.

Also, the same frequency can be used in all base stations (frequency repetition can be realized).

FIG. 3 is a diagram showing an example of a method of multiplying an information symbol by a spreading code when transmitting a signal in a radio base station of a multicarrier CDMA mobile communication system according to the present embodiment.

In the example of FIG. 3, the short code sequence length S
F is 4, and the sequence length L of the long code is four times the number N of subcarriers, that is, L = 4N. Here, the sequence length is synonymous with the repetition period of the spreading code. N is a natural number.

When the short code sequence length SF is 4,
In N subcarriers, N / SF (= N / 4) information symbols are transmitted in parallel (simultaneously).

The N / SF (= N / 4) information symbol sequences are copied for each information symbol by the number of symbols (four in the example shown in FIG. 3) equal to the short code sequence length, and Arranged above.

Then, the arranged information symbol sequence on the frequency axis is multiplied by a short code. Further, the information symbol sequence on the frequency axis that has been multiplied to have a sequence length N is multiplied by a long code.

In the example of FIG. 3, when multiplying the short code, each information symbol is copied, then arranged in the frequency axis direction, and multiplied by the short code. However, each information symbol is spread by the short code. After doing
The procedure of multiplying the long code and arranging the information symbol sequence multiplied by the long code in the frequency axis direction, or `` spreading each information symbol by the product of the short code and the long code, and then dividing the spread information symbol sequence by the frequency axis A procedure for arranging in the directions may be used.

By using the method of multiplying the spreading code shown in FIG. 3, the information symbol sequence is duplicated and arranged on the frequency axis, and the information symbols arranged on the frequency axis are multiplied by the long code and the short code. A method of transmitting a signal by transmitting using a plurality of subcarriers can be realized.

As a result, in the multi-carrier CDMA system, in addition to the conventional spreading using only the short code, the spreading code can be efficiently allocated by multiplying by the long code.

FIG. 4 is a diagram showing another example of a method of multiplying an information symbol by a spreading code when transmitting a signal in a radio base station of a multicarrier CDMA mobile communication system according to the present embodiment. .

FIG. 4A shows a sequence length L of a long code.
Is an example of multiplication of a spreading code when the number N of subcarriers is three times, that is, when L = 3N. FIG.
In the example shown in (a), multiplication of long codes is performed for three information symbol sequences transmitted simultaneously on the frequency axis.

FIG. 4B shows an example of multiplication of a spreading code when the long code sequence length L is 5.5 times the number of subcarriers N, that is, L = 5.5N. In this example,
Simultaneously multiplies the long code for the five information symbol sequences on the frequency axis and up to the sixth subcarrier # N / 2 on the frequency axis, and then simultaneously transmits the information symbol sequences on the frequency axis The multiplication of the long code is performed again for the subcarrier # N / 2 + 1 of the sixth sequence and the subsequent five information symbol sequences.

In the multi-carrier CDMA system, when performing despreading and coherent demodulation, a channel estimation value for each subcarrier is required. In order to derive this channel estimation value, it is necessary to average pilot symbols in the time direction for each subcarrier, so it is necessary to make the spreading pattern of the long code different for each base station in the time direction . This can be realized by using the method of multiplying the spreading code shown in FIG.

FIG. 5 is a diagram showing another example of a method of multiplying an information symbol and a spreading code when transmitting a radio base station of a multicarrier CDMA mobile communication system according to the present embodiment. In the example shown in FIG. 5, a sequence length L of a long code uses a value equal to the number N of subcarriers.

FIG. 5A shows that, when multiplying a long code in the frequency direction, each of the long codes to be multiplied by different information symbol sequences in the time axis direction is sequentially replaced by one chip in the frequency direction from the immediately preceding one, that is, a copy. This is an example of a case where multiplication is performed by shifting one information symbol at a time.

FIG. 5B shows an example in which multiplication is performed by shifting two chips, that is, two information symbols, in the frequency direction.

As described above, by using the spreading code multiplication method as shown in the example of FIG. 5, the long code is multiplied not only in the frequency axis direction but also in the time axis direction. Therefore, when integrating pilot symbols in the time direction to perform channel estimation on each subcarrier, signals from each cell can be distinguished, and as a result, channel estimation can be performed with higher accuracy.

FIG. 6 shows a configuration example of a transmission device (provided in a radio base station) which can be used in the multicarrier CDMA radio communication system according to the present embodiment, and FIG. 1 shows a configuration example of a corresponding receiving device (provided in a mobile station).

The transmitting apparatus shown in FIG. 6 includes a transmission data generator 11 for generating transmission data, an encoder 12 for encoding transmission data, a data modulator 13 for modulating the encoded transmission data, Multiplexing section 14 for multiplexing the modulated and modulated transmission data with pilot symbols,
A serial-to-parallel conversion unit 15 that performs serial-to-parallel conversion on the output of the copy, a copy 16 that copies each output of the serial-to-parallel conversion unit 15, a short code generator 17 that generates a short code, , And a combiner 20 that combines the outputs of the multipliers 18.
And a long code generator 21 for generating a long code
And a plurality of multipliers 22 for multiplying the output of the combiner 20 by the long code, and IFFT (Inverse Fast Fourier Transfo
rm) or IDFT (Inverse Discrete Fourtier Trans
form) to perform an IFFT (IDFT) circuit 23
The output of the FFT (IDFT) circuit 23 is GI (Guard Inte
rval) is inserted.

In the configuration shown in FIG. 6, the transmission data generator 11
, An encoder 12, a data modulation unit 13, and a multiplexing unit 14.
, A serial-to-parallel converter 15, a copy 16, a short code generator 17, and a plurality of parts 10 including a multiplier 18 are provided.

The receiving apparatus shown in FIG. 7 includes a symbol timing detecting section 31 for detecting a symbol timing in a received signal.
A GI removing unit 32 for removing the GI from the received signal;
The FFT (Fast Fourier Transfor
m) an FFT circuit 33 for performing processing, a channel estimation unit 34 for performing channel estimation, a plurality of multipliers 35 for multiplying an output of the FFT circuit 33 by an output of the channel estimation unit 34,
A long code generator 36 for generating a long code, a plurality of multipliers 37 for multiplying the output of the multiplier 35 by the long code, a short code generator 38 for generating a short code, and an output of the multiplier 37 A plurality of multipliers 39 for multiplying the short code sequence length SF by the short code, an adder 40 for adding each short code sequence length SF of the output of the multiplier 39, and parallel / serial conversion to the output of the adder 40 Parallel-to-serial conversion unit 41 that performs
A data demodulation unit 42 for demodulating the output of
2 is a decoder 43 which decodes the output of 2 and obtains restored data.

FIG. 8 shows another configuration example of a transmission device (provided in a radio base station) which can be used in the multicarrier CDMA radio communication system according to the present embodiment, and FIG. 2 shows another configuration example of the receiving apparatus (provided in the mobile station) corresponding to (1). 8 and 9, the same components as those in FIGS. 6 and 7 are denoted by the same reference numerals.

The transmitting apparatus shown in FIG. 8 has a multiplier 2 having the configuration shown in FIG.
6 in that one multiplier 19 for multiplying the output of the short code generator 17 by the long code is provided between the short code generator 17 and the multiplier 18 instead of FIG.

The receiving apparatus shown in FIG. 9 has a multiplier 3 having the configuration shown in FIG.
7 in that one multiplier 44 for multiplying the output of the short code generator 38 by the long code is provided between the short code generator 38 and the multiplier 39 instead of FIG.

The transmitting apparatus of FIG. 6 operates as follows based on the flowchart shown in FIG.

First, the transmission data sequence input from the transmission data generator 11 is encoded by the encoder 12 and modulated by the data modulator 13. Then, the pilot symbol is multiplexed with the coded and modulated transmission data sequence by the multiplexing unit 14 and serial-to-parallel converted by the serial-to-parallel converter 15 (step S1). Each information symbol of the series of N / SF information symbols subjected to the serial / parallel conversion is copied by the number of symbols equal to the short code sequence length (chip length) at copy 16, and these copies are arranged on the frequency axis. Thus, a first information symbol sequence is obtained (step S2).

Next, the first information symbol sequence arranged on the frequency axis is multiplied by the short code by the multiplier 18 to obtain a second information symbol sequence (step S3).

Next, the second information symbol sequence of sequence length N multiplied by the short code on the frequency axis
The multiplier 22 multiplies the combined second information symbol sequence by a long code to obtain a third information symbol sequence (step S4).

Next, the sequence length N multiplied by the long code
Is input to the IFFT circuit 23 and the GI insertion unit 24 to obtain an orthogonal multicarrier signal having N subcarriers. These orthogonal multicarrier signals are transmitted using a plurality of carriers (step S5).

When the transmitting apparatus shown in FIG. 8 is used, steps S3 and S4 are integrated and the first information symbol sequence is multiplied by the product of the short code and the long code.

The receiving apparatus of FIG. 7 operates as follows based on the flowchart shown in FIG.

First, the symbol timing (FFT timing) is detected by the symbol timing
The GI is removed by the I remover 32, and the obtained signal is separated into subcarrier components by the FFT circuit 33 (step S1).
1). Then, the channel estimation unit 34 estimates the channel variation value of each subcarrier, and the multiplier 35 compensates for the channel variation (step S12).

Next, the multiplier 37 multiplies the symbol, for which the channel fluctuation in each subcarrier has been compensated, by the long code in the subcarrier direction (step S13).
A multiplier 39 multiplies the symbol multiplied by the long code.
Is multiplied by the corresponding short code in the subcarrier direction (step S14). Then, the symbols of the short code sequence length (chip length) SF are added by the adder 40 to obtain a despread symbol (step S).
15).

Next, the despread symbols are parallel-to-serial converted by the parallel-serial converter 41 (step S16), and the obtained signal is demodulated by the data demodulation unit 42 and decoded by the decoder 43. Obtained (Step S17).

When the receiving apparatus of FIG. 9 is used, steps S13 and S14 are integrated, and the product of the short code and the long code is multiplied by the symbol of each subcarrier whose channel fluctuation has been compensated. .

In the transmitting device of FIGS. 6 and 8 and the receiving device of FIGS. 7 and 9, the long code generator can generate a long code by various methods.

For example, when the spreading code multiplication method shown in FIG. 4 is used, the long code generator stores all the long codes used in the system in a memory, and uses the long code used for data transmission at the time of data transmission. Read the code from memory. Alternatively, the long code generator stores a calculation formula for generating a long code in a memory, reads a calculation formula for generating a long code used for data transmission from the memory at the time of data transmission, and reads the calculated calculation formula. Generate the long code based on the expression.

Similarly, when the spreading code multiplication method shown in FIG. 5 is used, the long code generator stores all the long codes used in the system in a memory and uses them for data transmission at the time of data transmission. The long code is read from the memory, and the read long code is shifted by the shifter. Alternatively, the long code generator stores a calculation formula for generating a long code in a memory, reads a calculation formula for generating a long code used for data transmission from the memory at the time of data transmission, and reads the calculated calculation formula. The long code is generated based on the equation, and the generated long code is shifted by the shifter.

The processing procedure of the transmitting apparatus and the processing procedure of the receiving apparatus in the above-described embodiment are recorded as a program on a recording medium such as a CD or FD, and this recording medium is incorporated in a computer system, or The program recorded in the computer is downloaded to a computer system via a communication line, or installed from a recording medium, and the computer system is operated by the program to function as an apparatus for performing a signal transmission method and a signal reception method. be able to.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications within the technical scope thereof.

[0076]

As described above, in the multi-carrier CDMA mobile communication system according to the present invention, in addition to a user identification code (spreading code) for identifying a user, a cell-specific code for identifying a cell is used. Spread double with long code. Specifically, a long code having a repetition period equal to or longer than the number of subcarriers is used.

Further, by multiplying the long code by shifting it in the frequency direction, the multiplication of the long code can be realized not only in the frequency direction but also in the time direction. In the integration of the pilot symbols in the time direction performed in the above, signals from the respective cells can be distinguished.

Therefore, according to the present invention, spreading codes can be efficiently allocated in the downlink of a mobile communication system using the multi-carrier CDMA system.

Further, in the multi-carrier CDMA system in which the information symbol sequence is spread in the frequency axis direction, the channel estimation accuracy can be improved and the radio base station can be identified.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a conventional spreading code allocation method in a downlink of an asynchronous system between base stations and a synchronous system between base stations.

FIG. 2 shows a multicarrier C according to an embodiment of the present invention.
FIG. 3 is a diagram for explaining an example of a spreading code assignment method in a DMA mobile communication system.

FIG. 3 shows a multicarrier C according to an embodiment of the present invention.
The figure which shows an example of the multiplication method of the information symbol and the spreading code in the radio base station in the mobile communication system of a DMA system.

FIG. 4 shows a multicarrier C according to an embodiment of the present invention.
The figure which shows the other example of the multiplication method of the information symbol and the spreading code in the radio base station in the mobile communication system of a DMA system.

FIG. 5 shows a multicarrier C according to an embodiment of the present invention.
The figure which shows the other example of the multiplication method of the information symbol and the spreading code in the radio base station in the mobile communication system of a DMA system.

FIG. 6 shows a multicarrier C according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration example of a transmission device in a wireless base station in a DMA mobile communication system.

FIG. 7 shows a multicarrier C according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration example of a receiving device in a mobile station in a mobile communication system of the DMA system.

FIG. 8 shows a multicarrier C according to an embodiment of the present invention.
FIG. 9 is a block diagram showing another configuration example of a transmission device in a radio base station in a DMA mobile communication system.

FIG. 9 shows a multicarrier C according to an embodiment of the present invention.
FIG. 9 is a block diagram showing another configuration example of the receiving device in the mobile station in the mobile communication system of the DMA system.

FIG. 10 is a flowchart showing a processing procedure of signal transmission by the transmission device shown in FIG. 6 or 8;

FIG. 11 is a flowchart showing a processing procedure of signal reception by the receiving device shown in FIG. 7 or 9;

[Explanation of symbols]

100, 102, 200, 202 Long code layer 101, 103, 201, 203 Short code layer 104, 106, 108, 110, 112, 114, 2
04, 206, 208, 210, 212, 214 Radio cell 11 Transmission data generator 12 Encoder 13 Data modulator 14 Multiplexer 15 Serial / parallel converter 16 Copy 17, 38 Short code generator 18, 19, 22, 35 , 37, 39, 44 Multiplier 20 Combiner 21, 36 Long code generator 23 IFFT (IDFT) circuit 24 GI insertion unit 31 Symbol timing detection unit 32 GI removal unit 33 FFT circuit 34 Channel estimation unit 40 Adder 41 Parallel series Conversion unit 42 Data demodulation unit 43 Decoder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sadayuki Abeta 2-1-1, Nagatacho, Chiyoda-ku, Tokyo Inside NTT DoCoMo, Inc. (72) Inventor Mamoru Sawabashi 2-chome, Nagatacho, Chiyoda-ku, Tokyo No. 11 F-term in NTT DOCOMO, INC. (Reference) 5K022 EE02 EE11 EE21 EE31 5K067 CC10 DD17 DD19 EE02 EE10 HH21 HH36

Claims (19)

[Claims] 1. A radio base station duplicates each information symbol of an information symbol sequence to be transmitted, arranges the duplicated information symbols on a frequency axis, and applies a spreading code to the duplicated information symbols arranged on the frequency axis. A spreading code allocation method in a mobile communication system for transmitting a signal by transmitting a signal by multiplying and transmitting an information symbol sequence multiplied by a spreading code using a plurality of subcarriers, the number being equal to the number of duplicated information symbols A step of commonly assigning a short code used to identify a mobile station to a radio base station having a repetition period; and a base station having a repetition period longer than the number of duplicated information symbols. Individually assigning one or more long codes used to identify stations to each of the radio base stations A method for allocating a spreading code in a mobile communication system, characterized in that: 2. A method for transmitting a signal from a radio base station in a mobile communication system, comprising: (a) duplicating each information symbol of an information symbol sequence to be transmitted, and arranging the duplicated information symbols on a frequency axis; (B) For the duplicated information symbols arranged on the frequency axis, a short code having a repetition period equal to the number of duplicated information symbols and a long code having a repetition period longer than the number of duplicated information symbols. Multiplying a spreading code including a code to obtain a spreading information symbol sequence obtained by doubly spreading the information symbol sequence; and (c) transmitting the spreading information symbol sequence using a plurality of subcarriers. A signal transmission method, comprising: 3. The method according to claim 1, wherein the step (b) is used to identify a mobile station and to identify one of a group of short codes commonly assigned to all radio base stations and each base station. 3. The signal transmission method according to claim 2, wherein one of one or more long codes individually assigned to each of the wireless base stations is multiplied. 4. The long code has a sequence length longer than the number of subcarriers, and the step (b) has a sequence length equal to the number of subcarriers by multiplying by a short code. The signal according to claim 2, wherein a short code multiplied information symbol sequence to be transmitted is obtained, and the spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code. Transmission method. 5. The method according to claim 1, wherein the long code has a sequence length equal to the number of the subcarriers, and the step (b) has a sequence length equal to the number of the subcarriers by multiplying the short code. The short code multiplied information symbol sequence to be transmitted is obtained, and a long code to be multiplied by each of the different short code multiplied information symbol sequences on the time axis is multiplied by the immediately preceding short code multiplied information symbol sequence in the frequency direction. 3. The signal transmission method according to claim 2, wherein the spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code while sequentially shifting by one or a plurality of information symbols. 6. A method for receiving a signal at a mobile station in a mobile communication system, comprising: (a) receiving a spread information symbol sequence transmitted from a radio base station using a plurality of subcarriers; The spread information symbol sequence is multiplied by a long code and a spread code including a short code having a shorter sequence length than the long code, and a number of spread code multiplied information symbols equal to the sequence length of the short code are synthesized. Obtaining a despread information symbol sequence obtained by doubly despreading the spread information symbol sequence. 7. The step (b) is used to identify each mobile station and one of short code groups commonly assigned to all radio base stations and each base station. 7. The signal receiving method according to claim 6, further comprising multiplying one of one or more long codes individually assigned to each of the radio base stations. 8. A transmitting apparatus for transmitting a signal from a radio base station in a mobile communication system, wherein each information symbol of an information symbol sequence to be transmitted is copied,
For the duplicated part that arranges duplicated information symbols on the frequency axis, and for the duplicated information symbols arranged on the frequency axis,
The information symbol sequence is multiplied by a spreading code including a short code having a repetition period equal to the number of duplicated information symbols and a long code having a repetition period longer than the number of duplicated information symbols. A transmission apparatus, comprising: a spreading unit that obtains a spread information symbol sequence that is heavily spread, and a transmission unit that transmits the spread information symbol sequence using a plurality of subcarriers. 9. The spreading section is used to identify a mobile station, and is used to identify one of a short code group commonly assigned to all wireless base stations and each base station. 9. The transmitting apparatus according to claim 8, wherein one of one or more long codes individually assigned to each of the base stations is multiplied. 10. The long code has a sequence length longer than the number of subcarriers, and the spreading unit multiplies by a short code to transmit simultaneously with a sequence length equal to the number of subcarriers. 9. The transmitting apparatus according to claim 8, wherein a short code multiplied information symbol sequence is obtained, and the spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code. 11. The long code has a sequence length equal to the number of subcarriers, and the spreading unit multiplies by a short code to transmit simultaneously with a sequence length equal to the number of subcarriers. A short code multiplied information symbol sequence is obtained, and a long code for multiplying each of the different short code multiplied information symbol sequences on the time axis is multiplied by 1 or 9. The transmitting apparatus according to claim 8, wherein the spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code while sequentially shifting by a plurality of information symbols. 12. A receiving device for receiving a signal at a mobile station in a mobile communication system, comprising: a receiving unit that receives a spread information symbol sequence transmitted from a wireless base station using a plurality of subcarriers; The symbol sequence is multiplied by a long code and a spreading code including a short code having a shorter sequence length than the long code, and a spreading code multiplied information symbol having the same number as the short code sequence length is synthesized, and the spreading is performed. A despreading unit for obtaining a despread information symbol sequence obtained by doubly despreading the information symbol sequence. 13. The despreading unit is used to identify a mobile station, and is used to identify one of short code groups commonly assigned to all radio base stations and each base station. 13. The receiving apparatus according to claim 12, wherein one of one or more long codes individually assigned to each of the radio base stations is multiplied. 14. A recording medium recording a computer program code for causing a computer to function as a transmitting device for transmitting a signal from a radio base station in a mobile communication system, wherein the computer program code comprises an information symbol sequence to be transmitted. Duplicate each information symbol of
For the first computer program code for arranging the duplicated information symbols on the frequency axis, and for the duplicated information symbols arranged on the frequency axis,
The information symbol sequence is multiplied by a spreading code including a short code having a repetition period equal to the number of duplicated information symbols and a long code having a repetition period longer than the number of duplicated information symbols. A second computer program code for obtaining a spread information symbol sequence that is heavily spread, and a third computer program code for transmitting the spread information symbol sequence by using a plurality of subcarriers. . 15. The second computer program code is used to identify a mobile station, and is used to identify one of a short code group commonly assigned to all radio base stations and each base station. 15. The recording medium according to claim 14, wherein one of one or more long codes individually allocated to each of the radio base stations used for the multiplication is multiplied. 16. The long code has a sequence length longer than the number of subcarriers, and the second computer program code has a sequence length equal to the number of subcarriers by multiplying by a short code. 15. The spread information symbol sequence is obtained by obtaining a short code multiplied information symbol sequence to be transmitted simultaneously and multiplying the short code multiplied information symbol sequence into a plurality of short code multiplied information symbol sequences by a long code. Recording medium. 17. The long code has a sequence length equal to the number of subcarriers, and the second computer program code has a sequence length equal to the number of subcarriers by multiplying by a short code. The short code multiplied information symbol sequence to be transmitted at the same time is obtained, and the frequency is calculated from the long code obtained by multiplying the previous short code multiplied information symbol sequence by the long code multiplied by each of the different short code multiplied information symbol sequences on the time axis. 2. The spread information symbol sequence is obtained by multiplying a plurality of short code multiplied information symbol sequences by a long code while sequentially shifting the information symbol sequence by one or more information symbols in the direction.
5. The recording medium according to 4. 18. A recording medium recording a computer program code for causing a computer to function as a receiving device for receiving a signal at a mobile station in a mobile communication system, wherein the computer program code is transmitted from a radio base station to a plurality of subcarriers. And a first computer program code for receiving the spread information symbol sequence transmitted using the above, multiplying the spread information symbol sequence by a long code and a spread code including a short code having a shorter sequence length than the long code And a second computer program code for combining the number of spread code multiplied information symbols equal to the sequence length of the short code to obtain a despread information symbol sequence obtained by doubly despreading the spread information symbol sequence. A recording medium comprising: 19. The second computer program code is used to identify a mobile station, and is used to identify one of a short code group commonly assigned to all radio base stations and each base station. 19. The recording medium according to claim 18, wherein one of one or more long codes individually assigned to each of the radio base stations used for the multiplication is multiplied.