JPH0918450A - Code division multiplex transmitter - Google Patents

Abstract

PURPOSE: To freely select and set information quantity to be transmitted and a data rate at every frame and to reduce the scale of a circuit which performs code division multiplexing. CONSTITUTION: A frame generating part 102 performs the setting of a channel parameter and the allocation of the number of data bits of transmission data inputted in series from an input buffer 101 at every frame, and performs the convolution coding and punctured coding of a frame at every channel. After that, an orthogonally coded Walsh chip is inputted sequentially to the frame size memory 92 of a code multiplex part 109 by multiplying a Walsh code, and addition is performed according to the use/disuse of the channel by an adder 91, and code division multiplex data of one frame is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code division multiplexing transmission apparatus for transmitting code division multiplexed data.

[0002]

2. Description of the Related Art Conventionally, when transmitting data for a plurality of channels within one band, generally, data is divided and multiplexed. A method of performing this division multiplexing is frequency division multiplexing, so-called FDM (Frequency).
Division Multiplex) method, time division multiplexing, so-called TD
M (Time Division Multiplex) method, code division multiplexing,
There is a so-called CDM (Code Division Multiplex) system and the like.

In the CDM system, data composed of a plurality of channels and divided into a plurality of layers at different data rates are weighted so that each layer can be identified, and further, in the same time-frequency space. Each channel is divided by performing orthogonal transformation using the spreading orthogonal code, and the error rate is corrected by changing the coding rate for each channel by convolutional coding and punctured coding, and the importance of data is The layered transmission is performed according to the above. By using this CDM system, hierarchical transmission can be realized more easily than other division multiplexing systems in the field of broadcasting, and in the field of mobile communication, it is combined with a spread spectrum system by direct spreading. As a result, the call capacity can be made larger than that of other division multiplexing systems.

Therefore, in the field of broadcasting, the practical application of this CDM system is being studied as a transmission system of digital video signals. Also, in the field of mobile communication, in a cellular telephone system of a code division multiple access system, a so-called CDMA system, C code is used to divide each orthogonally encoded channel into a control channel and a traffic channel.
The DM method is used.

[0005]

By the way, in the above-mentioned digital video signal transmission and CDMA system cellular telephone system, the number of channels to be used and the values of channel parameters such as the data rate set for each channel are Since it is often known, it is necessary to select a channel or determine a data rate for each channel according to a predetermined procedure. In a CDMA cellular telephone system, variable data rate transmission is performed on a traffic channel, which is fixed at 1
Since only the channel is used to determine the data rate, it is difficult to transmit high speed data.

Further, when changing the channels to be used, the total number of channels, and the data rate assigned to each channel, it is necessary to use the control channel and control information to make a change according to a predetermined procedure. .

That is, digital video signal transmission and CDM
In the A-system cellular telephone system, the receiving device cannot decode the received data unless the transmitting device determines the channel parameters according to a predetermined procedure.

In view of the above situation, the present invention is a CD.
It is intended to provide a code division multiplexing transmission device capable of freely selecting a channel parameter to be used when transmitting data using the M method.

[0009]

A code division multiplexing transmission apparatus according to the present invention comprises, for each number of channels equal to or less than the number of channels determined by orthogonal encoding, presence / absence of a channel and a data rate when the channel is used. Set the channel parameters and assign the number of data bits for each channel based on this channel parameter.
Based on the channel parameter, a frame generating means for outputting as data the data for the number of channels equal to or less than the number of channels determined by the orthogonal encoding,
Convolutional coding means for sequentially performing convolutional coding for each channel of the frame data from the frame generation means, and data for each channel from the convolutional coding means with a symbol erasure pattern corresponding to a predetermined data rate. Using a punctured code having, based on the data rate of the channel parameters, sequentially punctured coding means to generate a punctured coding means for generating a symbol, and a symbol for each channel from the punctured coding means, Orthogonal coding means for multiplying the orthogonal codes assigned to the respective channels to sequentially perform the orthogonal coding, and based on the presence or absence of use of the channel of the channel parameter, one frame of each channel from the orthogonal coding means. A code that sequentially adds the outputs and outputs a code division multiplexed signal And a duplex unit, to solve the problems described above by transmitting a variable data rate for each frame of the frame data.

Further, the present invention is characterized in that a spread spectrum means for spreading spectrum using a pseudo noise code is provided for the code division multiplexed signal for each frame from the code multiplexing means.

[0011]

According to the present invention, channel parameters including presence / absence of channels and a data rate when the channels are used are set for each of the channels which is equal to or less than the number of channels determined by orthogonal coding, and a frame based on the channel parameters is set. For each channel of data, convolutional coding and punctured coding are sequentially used, and after orthogonal coding is performed by multiplying the orthogonal code assigned to each channel, based on the presence or absence of channel use of the above channel parameter. Then, the outputs of the orthogonally encoded one frame for each channel are sequentially added and transmitted at a data rate that is variable for each frame, thereby serially processing the input serial data.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a code division multiplexing transmission apparatus according to the present invention.

The code division multiplex transmission apparatus shown in FIG. 1 has a number of channels equal to or less than the number of channels determined by orthogonal coding.
Channel parameters consisting of whether or not a channel is used and the data rate when the channel is used are set, and the number of data bits for each channel is assigned based on this channel parameter. A frame generation unit 102 that is a frame generation unit that outputs data for channels as frame data, and convolutional coding that sequentially performs convolutional coding for each channel of the frame data from the frame generation unit 102 based on the channel parameters. A convolutional encoder 103, which is a means, and a punctured code having a symbol erasure pattern corresponding to a predetermined data rate is used for the data for each channel from the convolutional encoder 103, and based on the data rate of the channel parameter. There are performed sequentially punctured encoding and punctured encoder 104 is punctured encoding means for producing symbols, the symbols of each channel from the punctured encoder 104, Walsh
Based on the multiplier 107, which is an orthogonal encoding means for sequentially multiplying the orthogonal code assigned to each channel generated by the code generator 106 and performing orthogonal encoding, and based on the presence / absence of use of the channel of the above channel parameter, It comprises a code multiplexing unit 109 which is a code multiplexing means for sequentially adding the output of each channel for one frame from the multiplier 107 and outputting a code division multiplexed signal.

Here, a schematic configuration of a code division multiplexing unit for performing code division multiplexing for each channel, which is a premise of the technology of the code division multiplexing transmission apparatus of the present invention, is shown in FIG. 2 and explained below. To do.

When one frame consists of 8 channels, the transmission data serially input frame by frame is sent by the serial / parallel converter 301 to the channel C.
It is converted into parallel data for eight Walsh channels of H _{0 to} CH ₇ . Data of 8 channels are sent are input to the convolutional encoder 302 _{1-302 8,} error-correction-coded by the convolutional code, the punctured coder 303 _{1-303 8} respectively. In these punctured encoders 302 ₁ to 302 _8, according to the assigned data rate, punctured coding the set coding rate is performed.

These punctured encoders 303 _{1 to} 3
03 ₈ outputted from the transmission symbols that are contiguous on the time axis, rearranged is input to the interleaver 304 _{1-304 8,} burst error of a transmission path is randomized. Transmission symbols of each channel that has been modified such arrangement are respectively sent to multipliers 306 _{1 to 306 8.} Here, the Walsh code generator 305, Walsh code determined for each channel is generated and sent respectively to the multiplier 306 _{1 to 306 8.} In this way, the multiplier 306 _{1 to 306 8,} the transmission symbols and Wa from the interleaver 304 _{1-304 8}
The Walsh code from the lsh code generator 305 is multiplied for each channel to obtain each Wals
A Walsh chip is generated for each h channel.

The Walsh chips of these eight channels of Walsh channels are added by the adder 307 by matching the heads of the frames, and a code division multiplexed signal is output.

First, Table 1 shows the specifications of the code division multiplexing system in the code division multiplexing transmission apparatus of this embodiment.

[0019]

[Table 1]

As shown in Table 1, in the code division multiplexing transmission apparatus of this embodiment, the Walsh chip rate in the orthogonal encoding by the Walsh code is 2048 Mc.
ps, and the orthogonal division is performed with the Walsh code of the eight channels of the Walsh channels W _{0 to} W ₇ to perform channel division. In addition, the PN chip rate in DS (Direct Sequence) spread spectrum is 4096 Mc.
ps, the PN sequence length is 8 when one cycle is 2 msec.
192.

The transmission data input to the code division multiplexing transmission apparatus of the embodiment shown in FIG. 1 is serial data. The transmission data is stored in the input buffer 101 and then sent to the frame generation unit 102.

The frame generator 102 sets channel parameters and allocates the number of data bits of the transmission data input from the input buffer 101 for each frame. Specifically, if there is weighting information for serially input transmission data, according to this weighting information, as a channel parameter, whether or not a channel is used for each of a plurality of Walsh channels and data when the channel is used The rate is set. If there is no weighting information for the transmission data, the presence / absence of use of the channel and the data rate when the channel is used are individually set for each frame for a plurality of Walsh channels. The channel parameters set as above are used in the convolutional encoder 10
3, punctured encoder 104, interleaver 105,
Walsh code generator 106, gain controller 1
08, and is sent to the code multiplexing unit 109. As a result, the timing control of this code division multiplexing transmission device is performed.

Table 2 shows the specifications of each Walsh channel.

[0024]

[Table 2]

As shown in Table 2, the data rate of each Walsh channel in each channel is 128 kb.
It has a value of either ps, 192 kbps, or 224 kbps. The coding rate r ₁ of the convolutional code for each of these data rates is 1/2, and the constraint length K is
Is 7. Also, the coding rate r of the punctured code
No. ₂ is not set for data with a data rate of 128 kbps, and 3/4 for data with a data rate of 192 kbps and 7 for data with a data rate of 224 kbps.
It has a value of / 8.

Table 3 shows the specifications of the data of the frame composed of the Walsh channel having the above-mentioned specifications.

[0027]

[Table 3]

One frame period is 2 msec, and each data rate of the Walsh channels W _{1 to} W ₇ in this frame has a value of 128 kbps, 192 kbps, or 224 kbps.
These 128kbps, 192kbps, or 224k
The numbers of data bits including tail bits at a data rate of bps are 256 bits, 384 bits, and 448 bits, respectively. Since the number of tail bits is all 6 bits, the actual number of data bits is 25
There are 0 bits, 378 bits, and 442 bits. Also,
The number of symbols and the symbol rate subjected to convolutional coding and punctured coding are all the same value regardless of the data rate, and the number of symbols is 512 and the symbol rate is 25.
6 ksps.

According to the channel parameters set in the input transmission data, the number of data bits and the number of tail bits for each frame are counted in order of the Walsh channels W _{0 to} W ₇ for each frame. And
Clocks corresponding to the count of the number of data bits are transmitted to the input buffer 101, and clocks corresponding to the count of the number of tail bits of each frame are transmitted. Therefore, the transmission data from the input buffer 101 is synchronized with the clock signal and has a data bit number of 250 bits, 378 bits, or 442 bits in the frame generation unit 10.
2 is input.

6 is added for each frame in accordance with the clock corresponding to the count number of the input tail bits.
The bit tail bits (0,0,0,0,0,0) are generated. Thereby, for each Walsh channel, 6 tail bits are output after the data bit is transmitted. The output data for each frame is sent to the convolutional encoder 103.

Here, concrete allocation of channel parameters is shown in FIG.

FIG. 3 shows the data rate of the Walsh channel and the total data rate from the first frame to the ninth frame. In the first and second frames, Walsh channels W ₀ , ..., W ₇ are assigned data rates 128, ..., 224 kbps, and the total data rate is transmitted at 1.536 Mbps. The number of data bits per frame is 3072 bits. Wals on the third frame
Data rates 128, 128, unused, ..., Unused, 192 kbps are assigned to the h channels W ₀ , W ₁ , W ₂ , ..., W ₆ , W ₇ , respectively, and the total data rate is transmitted at 928 kbps. This means that the number of data bits per frame is 1856 bits. Similarly, in each of the fourth frame to the ninth frame, the data rate of the Walsh channel for 8 channels is allocated.

In the convolutional encoder 103, the convolutional encoder 103 performs the convolutional encoding with the coding rate r ₁ and the constraint length K according to the channel parameter assigned by the frame generation unit 102. This convolutionally encoded data is the punctured encoder 1
04.

The punctured encoder 104 performs punctured encoding as needed.

It should be noted that convolutional coding and punctured coding are types of error correction coding, and convolutional coding consists of several bits preceding each encoder input bit and the currently input bit. The punctured coding is a coding method in which mod2 addition is performed and the result is output bits. Punctured coding is coding in which a part of coded bits regularly generated by an error correction coder is erased according to a certain rule. Is the way.

That is, the punctured coder 104 performs punctured coding using the coding rate r ₂ in accordance with the channel parameters assigned by the frame generation section 102, and a part of the coded bits. Enhance the coding while erasing. Specifically, when the data rate is 128 kbps, encoding is not performed, and when the data rate is 192 kbps, the coding rate r ₂ = 3/4
The punctured code is used for coding, and when the data rate is 224 kbps, the punctured code is coded with a coding rate r ₂ = 7/8. As a result, the error correction coded and punctured coded symbols are 1
512 symbols are generated per frame. Thereafter, the transmission symbols output from the punctured encoder 104 are sent to the interleaver 105.

The interleaver 105 rearranges the transmission symbols continuous on the time axis according to the channel parameters assigned by the frame generator 102, and randomizes burst errors in the transmission path. Wals output from this interleaver 105
The transmission symbol for each h channel is sent to the multiplier 107.

Here, the Walsh code generator 106 generates orthogonal Walsh codes for each Walsh channel according to the channel parameters assigned by the frame generation unit 102. This Wals
The h-code is specifically shown in FIG. 4, for example. This Walsh code is sent to the multiplier 107.
Therefore, in the multiplier 107, the Wals from the Walsh code generator 106 is added to the transmission symbol for each Walsh channel output from the interleaver 105.
The h code is multiplied. The output from the multiplier 107 is sent to the gain controller 108. In the gain controller 108, the frame generator 10
Weighting is performed according to the channel parameters assigned in 2. For example, in the weighting in this embodiment, the amplitude of the transmitted symbol is 0, −, depending on the importance.
There are three levels of 3 and -6 dB. The output from the gain controller 108 is sent to the code multiplexing unit 109.

The code multiplexing unit 109 has a frame size memory 92 having a length of 4096 which is the number of Walsh chips per frame, an output from the frame size memory 92, and a gain set by the gain controller 108. Adder 91 for adding the transmission symbol
And a selector 93. In the code multiplexing unit 109, after the frame size memory 92 is reset, the orthogonally encoded 4096 Walsh chips of the Walsh channels W _{0 to} W ₇ are sequentially input to the frame size memory 92. At this time, according to the presence / absence of use of the channel set by the frame generation unit 102, when the channel is in use, the selector 9
The Walsh chip in the frame size memory 92 via 3 is sent to the adder 91, and the Wals is input next.
The value is added to the Walsh chip of the h channel and the value in the frame size memory 92 is updated. When the channel is not used, the frame size memory 92
Stop adding Walsh chips for one frame from. As a result, the code-division multiplexed data for one frame, which is obtained by adding the eight channels of the Walsh channels W _{0 to} W _7, is generated, and the code-division multiplexed data is sent to the multiplier 111.

The multiplier 111 includes a PN generator 110.
A PN sequence having a sequence length of 8192, which is a rectangular wave generated at random values of ± 1 levels, is input. As a result, in the multiplier 111, the code division multiplexed data output from the code multiplexing unit 19 and the P
When the PN sequence from the N generator 110 is multiplied,
Spread modulation is performed. This spread modulated transmit signal is
The band is limited by the transmission filter 112, converted into an analog signal by the D / A converter 113, up-converted to a desired RF frequency by the RF unit 114, and transmitted from the transmission antenna 115.

Further, FIG. 5 shows a flowchart of the data transmission procedure of the code division multiplexing transmission apparatus of this embodiment. Regarding the data transmission operation of this code division multiplexing transmission apparatus,
This will be specifically described.

First, in step S31, the initial value of each block is set, the frame size memory 92, the interleaver 105, and the convolutional encoder 103 are initialized, and the Walsh channel number is set to 0.

Then, in step S32, the serially input transmission data is stored in the input buffer 101, and in step S33, the stored transmission data is output to the frame generation unit 102, and the frame selection unit 1
In 02, channel parameters such as the presence / absence of a used channel for each Walsh channel, a data rate, and the number of data bits are set for each frame.

Then, in step S34, it is determined whether or not there is data. Here, if it is determined that the data does not exist, the process proceeds to step S57, the incremented Walsh channel number by adding 1 to the Walsh channel number, the next Walsh channel W _1, presence or absence of data in step S34 Is determined. The processing of steps S34 and S57 is performed until it is determined that there is data.

If it is determined in step S34 that there is data, the flow advances to step S35 to allocate the data rate and the number of bits according to the values set in the frame generation unit 102, and in step S36. Add 6 bits of tail bits. Then, step S3
In step 7, the convolutional encoder 103 performs convolutional code with a coding rate r ₁ = ½ and a constraint length K = 7 for each Walsh channel.

Thereafter, the data rate of the convolutionally coded data is determined in steps S38 and S39. First, in step S38, the data rate is 128 kbps.
Is determined. As a result, if it is determined that the data rate is 128 kbps, step S
At 42, the number of symbols per frame of data having a data rate of 128 kbps is 512 symbols. Also,
If it is determined in step S38 that the data rate is not 128 kbps, the process proceeds to step S39, and it is determined whether or not the data rate is 192 kbps. As a result, if it is determined that the data rate is 192 kbps, in step S10, the punctured encoder 1
In 04, coding is performed with a punctured code with a coding rate r _{2 =} 3/4. As a result, in step S42, the number of symbols per frame of the data having the data rate of 192 kbps is 512 symbols. Step S
If it is determined in 39 that the data rate is not 192 kbps, the data rate is 224 kbps, so the punctured encoder 104 uses the coding rate r ₂
= 7/8 punctured code is used for encoding. As a result, the number of symbols per frame of data having a data rate of 224 kbps is 512 in step S42.

When the symbol is generated in step S42, the interleaver 105 interleaves in step S43. In step S44, the beginning of the frame of each Walsh channel is matched with this interleaved data, and the W assigned to each channel is generated by the Walsh code generator 106.
The Alsh code is multiplied by the multiplier 107 and encoded. As a result, data for 8 channels is combined. The combined data of one frame is weighted by the gain controller 108 in step S45, and then processed by the code multiplexing unit 109.

In the code multiplexing unit 109, first, in step S46, the set Walsh channel number, that is, the Walsh chip of the Walsh channel W ₀ , is input to the frame size memory 92. And
In step S47, the adder 91 adds the Walsh chip of the Walsh channel W ₁ next input from the gain controller 108 and the value in the frame size memory 92 via the selector 93, and then in step S4
At 8, the value in the frame size memory 92 is updated. Then, in step S49, the currently set Wals is set.
The value of the h channel number is incremented to the next Wa
The lsh channel is set, and in step S50, the Wal
It is determined whether or not the sh channel number is set to 8.

As a result, if it is determined that the Walsh channel number is not yet set to 8, the processing up to the code multiplexing unit 109 is completed for the eight Walsh channels W _{0 to} W _7. Therefore, the process returns to step S34, and it is determined whether or not there is data of the newly set Walsh channel. If it is determined that there is data, step S35.
The processes from to S49 are performed.

If it is determined in step S50 that the Walsh channel number has been set to 8, then W
It is considered that the processing for 8 channels of the alsh channels W _{0 to} W ₇ is completed, and the process proceeds to step S51 to output the code division multiplexed signal obtained by adding 8 channels from the frame size memory 92. Specifically, for example,
In the third frame of FIG. 3, the data rate of the Walsh channels W ₀ , W ₁ , W ₃ , and W ₄ is assigned to 128 kbps, the data rate of the Walsh channel W ₅ is assigned to 224 kbps, and the data of the Walsh channel W ₇ is assigned. The rate is assigned to 192 kbps and is used respectively for the Walsh channel W ₂ ,
W ₆ is not used because there is no data. That is, 6 out of 8 channels are used and a code division multiplexed signal transmitted at a total data rate of 928 kbps is output.

This code division multiplexed signal is processed in step S5.
In step 2, in the multiplier 111, the spread spectrum of the DS method is performed by adjusting the timing so that the head of the frame matches the head of the PN sequence output from the PN generator 110. After this, the transmission filter 112 performs band limitation in step S53, and D / A in step S54.
The signal is converted into an analog signal in the converter, up-converted to a desired RF frequency in the RF unit 114 in step S55, and the transmission antenna 1 is converted in step S56.
Sent from 15.

[0052]

As is apparent from the above description, the code division multiplexing transmission apparatus according to the present invention determines whether or not a channel is used and whether or not the channel is used for each of the channels which is equal to or less than the number of channels determined by orthogonal coding. A channel parameter consisting of the time data rate is set, and based on this channel parameter, convolutional coding and punctured coding are sequentially performed for each channel of the frame data, and then orthogonal coding is performed to perform each one frame. The outputs of the channels are sequentially added to output a code division multiplexed signal,
By transmitting frame data at a variable data rate for each frame, if the number of channels is less than or equal to the determined number of channels or the determined data rate, the amount of information to be transmitted without using control channels or control information. The data rate can be freely selected and set for each frame. In addition, since the data rate is determined by the convolutional code and the punctured code, the data with high importance decreases the coding rate to increase the error correction capability, and the data with low importance increases the coding rate. It is possible to perform weighted layered transmission in which data is transmitted with reduced error correction capability. Furthermore, since high-speed data that is serially input can be code-division-multiplexed by serial processing with a single system circuit configuration, it has a circuit configuration for the number of orthogonal channels that satisfies the maximum communication capacity. There is no need, and the circuit scale can be reduced. Also, regardless of the increase or decrease in the number of orthogonal channels,
Since code division multiplexing can be performed with only one system circuit configuration, the number of orthogonal channels can be freely selected.

Further, by performing spread spectrum on the code division multiplexed signal for each frame using a pseudo noise code, high speed serial data is parallelized by code division multiplexing adapted to spread spectrum of the DS system, Since low-speed parallel data can be transmitted, the spreading processing gain per bit can be increased. This makes it possible to take measures against fading such as path diversity, so that it can be applied to mobile communications.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a code division multiplexing transmission apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram of a code division multiplexing unit that performs code division multiplexing for each channel.

FIG. 3 is a diagram showing allocation of channel parameters.

FIG. 4 is a diagram showing a specific example of a Walsh code.

FIG. 5 is a flowchart of a data transmission procedure of the code division multiplexing transmission device.

[Explanation of symbols]

 101 Input Buffer 102 Frame Generation Unit 103 Convolutional Encoder 104 Punctured Encoder 105 Interleaver 106 Walsh Code Generator 107, 111 Multiplier 108 Gain Controller 109 Code Multiplexing Unit 110 PN Generator 112 Transmission Filter 113 D / A Converter 114 RF Section 115 transmitting antenna 91 adder 92 frame size memory 93 selector

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04L 1/00 H04L 1/00 F 27/00 27/00 B

Claims (2)

[Claims] 1. A code division multiplexing transmission apparatus for code division multiplexing and transmitting data of a plurality of channels in one band by using an orthogonal code, for each number of channels equal to or less than the number of channels determined by orthogonal coding. Set the channel parameters consisting of whether or not the channel is used and the data rate when the channel is used,
A frame generation means for allocating the number of data bits for each channel based on this channel parameter and outputting as data the number of channels less than the number of channels determined by the orthogonal encoding as frame data; Then, convolutional coding means for sequentially performing convolutional coding for each channel of the frame data from the frame generation means, and symbol erasure corresponding to a predetermined data rate in the data for each channel from the convolutional coding means. Using a punctured code having a pattern, punctured coding means for sequentially performing punctured coding based on the data rate of the channel parameter to generate symbols, and a symbol for each channel from the punctured coding means To each channel The orthogonal coding means for multiplying the orthogonal code assigned to each of the channels to sequentially perform the orthogonal coding, and the output of each channel for one frame from the orthogonal coding means based on whether or not the channel of the channel parameter is used. A code division multiplexing transmission device which sequentially adds and outputs a code division multiplexing signal, and transmits the frame data at a data rate which is variable for each frame. 2. The code division multiplexing according to claim 1, further comprising a spectrum spreading means for performing spectrum spreading using a pseudo noise code on the code division multiplexed signal for each frame from the code multiplexing means. Transmission device.