JPH10164015A - Code generator for spread spectrum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spread spectrum code generation circuit for eliminating the need of a spreading code sequence generated for respective channels and simplifying and reducing a circuit. SOLUTION: A spreading code is calculated beforehand by an arithmetic unit 1 and the calculated result is written in a RAM 2 for a short code for the respective channels. At the time of transmission, a stored code sequence is outputted by a counter for read, input signals 3 are spread by the read sequence and spreading is performed once again by the output of a long code generation circuit 4 including the attributes of a base station or the like. Thereafter, the addition and subtraction of an amplitude value are performed by the spread values of the respective channels in a synthesis circuit 5 and the spread synthesis of the input signals is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum (Spread Spec) used for a mobile communication device or the like.
code) using the communication method (code)
The present invention relates to a Division Multiple Access apparatus.

[0002]

2. Description of the Related Art Conventionally, this type of spread spectrum communication apparatus is capable of multiplexing by code by allocating a specific code to each station, performing spreading using the code, and performing despreading with the same code on the receiving side. By using this method, it is possible to increase the system capacity per bandwidth and increase the resistance to interference.

[0003] As this kind of prior art, for example, Japanese Unexamined Patent Publication No.
Japanese Patent Application No. 84131 proposes a configuration of a code division multiplex communication device that simplifies a code division multiplex unit of a system.

FIG. 3 is a block diagram showing a configuration of a code division multiplexing device proposed in the above-mentioned Japanese Patent Application Laid-Open No. 8-84131. Referring to FIG. 3, transmission information 31 is input to one input terminal of address designating circuit 32. The addressing circuit 32 receives an address control signal 3 from another input terminal.
8, the address 33 of the memory 34 is specified based on the transmission information 31 and the address control signal 38. The output data 35 of the memory 34 represents data obtained by subjecting the transmission information 31 to a digital value by spectrum spreading with a spreading code and performing addition. By converting the output data 35 into an analog value by a D / A (digital / analog) converter 36, a code division multiplexed signal can be obtained.

[0005]

However, the above-described conventional code division multiplexing apparatus described with reference to FIG. 3 has the following problems.

A first problem is that the capacity of the memory 34 becomes large.

The reason is that the transmission information signal of each channel is spread with each spreading code, and the value obtained by adding code multiplexing is stored in the memory 34. For example, when the number of channels is doubled, the transmission The information pattern is four times the square and the storage memory capacity is four times as large. That is, since the memory capacity increases in the order of the square, when the number of channels is increased, the memory capacity becomes large.

A second problem is that the amplitude value cannot be changed during power control or the like.

The reason is that, in the above-mentioned prior art, since spreading and addition are performed in advance by a spreading code,
This is because a constantly changing amplitude value cannot be considered due to power control or the like.

[0010] In the above-described configuration of the prior art, even if the amplitude value is considered, a pattern obtained by multiplying the number of patterns of the amplitude value of each channel by the number of channels is required. As a result, a huge memory is required. It will be.

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a spreading code generator for use in spread spectrum communication, which requires a spreading code generating circuit for each channel. Without downsizing,
An object of the present invention is to provide a spread-spectrum code generator that has been simplified.

[0012]

In order to achieve the above object, a spread code generating circuit according to the present invention has a calculating means for calculating a spread code of each channel, and accumulates the spread code calculated by the calculating means. And a storage unit, wherein the input signal of each channel is spread with a code sequence stored in the storage unit,
Thereby, the spread code generation circuit for each channel is not required.

Further, in the present invention, only the spreading code is generated by the storage unit, and the calculation of the amplitude value information for power control is performed separately from the storage unit.

Further, according to the present invention, there is provided switch means for switching between a write address and a read address to the storage section storing the spread code of each channel and reading the spread code of each channel from the storage section. However, a specific spreading code can be written.

[0015]

Embodiments of the present invention will be described below. In a preferred embodiment of the present invention, an arithmetic unit (1 in FIG. 1) is provided instead of generating a spreading code for each channel required for code multiplexing using spread spectrum. After a code sequence is calculated in advance by an arithmetic unit, the contents are stored in a storage unit (2 in FIG. 1) and read out from the storage unit when necessary.

Further, in the preferred embodiment of the present invention, since only a circuit for generating a spread code is realized by the storage unit (2 in FIG. 1), it is necessary to consider an amplitude value such as power control. Is also possible.

More specifically, it has an arithmetic unit (1 in FIG. 1) for performing an operation and a short code RAM (2 in FIG. 1) for storing a spread code of each channel.

Further, in a preferred embodiment of the present invention, even when another spread code is being read from the storage section, the spread code of the storage section can be rewritten only for a specific channel. ing. More specifically, the storage unit includes a write address bus (25 in FIG. 2) output from the arithmetic unit (22 in FIG. 2) and a read address bus output from the counter (22 in FIG. 2). A bus (24 in FIG. 2) and a switch (26 in FIG. 2) for switching between them are provided.

As described above, in the embodiment of the present invention, since the storage unit in which the spreading code is stored in advance is used instead of the spreading code generating circuit for each channel, the circuit scale is reduced by constructing the code generating circuit. An increase can be prevented.

In the embodiment of the present invention, preferably, the read address of each channel is generated by the same counter (22 in FIG. 1). It becomes difficult.

Further, in the embodiment of the present invention,
2 addresses of write address and read address to the storage unit
Since one bus is used, it is possible to rewrite the spreading code only in a specific channel even when another channel is reading.

[0022]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Referring to FIG. 1, in the present embodiment,
The arithmetic unit 1 calculates in advance the sequence of the spreading code of each of the channels CH0 to CHn, and the calculation result is stored in the short code RAM (random access memory) 2 of each channel. The total capacity of the short code RAM 2 used here is the product of the length of the code sequence and the number of channels (n).

When transmission is performed, the input signal 3 of each channel is spread by a code sequence stored in the short code RAM 2 of each channel, and an attribute code used for identification of a base station or the like is then transmitted. The output of the long code generation circuit 4 to be generated and the spread signal of each channel that has been spread earlier are further spread.

The long code is a spreading code representing an attribute of a base station or the like, and has a long sequence and is not required for each channel. Therefore, the long code is generated by configuring an actual code generation circuit instead of a RAM. It is to let.

Thereafter, the signal spread by the short code and the long code is sent to the synthesizing circuit 5.
The amplitude value of each channel is added or subtracted by the spread value, and a spread synthesized output is obtained.

Next, the arithmetic unit 1 and the short code RAM 2 shown in FIG. 1 will be described in detail with reference to FIG.

Referring to FIG. 2, the short code sequence calculated by the arithmetic circuit 21 is transmitted from the data bus 23 to the short code.
The data is written to the short code RAM 27 of each channel at the address specified by the write address bus 25.

At this time, the switch 26 switches between the write address bus 25 and the read address bus 24.

The switch 26 is used for writing only when the write address 25 of each channel is designated. At the time of reading, the counter 22 generates a read address, and outputs the contents of the short code RAM 27 to the short code output 28 at the timing when each channel is synchronized.

The operation of the embodiment of the present invention will be described in detail with reference to FIGS.

Referring to FIG. 1, the arithmetic unit 1 gives an initial value to each channel sequence based on the short code generator polynomial during the configuration of the device or whenever the spreading code needs to be changed. Perform calculations. At this time, it is possible to automatically input a predetermined initial value, or to receive and input an initial value in order to match a spreading sequence with a base station like a mobile terminal. I have.

The calculated sequence is stored in the short code RAM 2 of each channel. At the time of storage, the write address bus 25 is selected by the switch 26 in FIG. 2 and written into the short code RAM 27 of each channel.

The switch 26 for selecting this address is
By the switching, even when one of the channels is in the write state, the other channel can read, so that the content of the short code RAM 27 can be changed even while the other channel is operating. It is said.

More specifically, the switch 26 opens and closes by looking at a predetermined upper address. For example, when the spreading code length is "256", an 8-bit counter 22 is provided, and the counter output is used as a read address. The write address is expressed using bits higher than 8 bits, for example, 4 bits of 9 to 12 bits, and the switch 26 is switched to the write side only when an address is specified from the arithmetic circuit 21. Have been.

At the time of reading, the output of the counter 22 becomes an address for reading, and each short code stored in the short code RAM 27 of each channel is read. Further, since the read address 24 is synchronized with each channel, the short code output 28 can also obtain a synchronized output.

With this short code, the input signal 3
(See FIG. 1).

The input signal 3 includes a symbol value of "1" or "0" and an amplitude value, and the symbol value is spread.

For this reason, the symbol value is left as it is,
By changing only the amplitude, power control and the like can be performed.

Thereafter, the output of the long code generation circuit 4 for generating a code indicating the attribute of the base station and the like, and the spread signal of each channel spread beforehand are further spread.

This output will indicate a particular user at a particular base station.

Next, the combining is performed by the combining circuit 5 based on the signals spread in each channel. Synthesis circuit 5
In, the addition and subtraction of the amplitude value are performed based on the spread value of each channel, and the combined output is obtained.

In the above embodiment, the spread spectrum code generator has been described. However, the present invention can be applied to a calculation circuit of an interference canceller such as a decorrelator.

[0044]

As described above, according to the present invention,
The following effects are obtained.

A first effect of the present invention is that a spreading code generation circuit conventionally required for each channel becomes unnecessary. Therefore, according to the present invention, the circuit scale is reduced, and the present invention can be applied to a portable terminal.

The reason is that in the present invention, a spreading code is calculated in advance by an arithmetic unit, stored in a storage unit (RAM) corresponding to each channel, and read out when necessary. .

A second effect of the present invention is that it can cope with a change in the amplitude value of a signal such as power control.

The reason is that, in the present invention, only the spreading code is generated by reading from the storage unit (RAM), and the operation such as addition and subtraction is performed outside the storage unit.

A third effect of the present invention is that the spreading code of a specific channel can be rewritten while reading the spreading code of each channel from the RAM.
For this reason, according to the present invention, a test or the like can be performed for a specific channel even in a service environment.

The reason is that, in the present invention, both the write address and the read address for the RAM are provided, and the read / write is selected by the upper bits of the write address.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating details of an arithmetic unit and a short code RAM unit according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a schematic configuration of a conventional code division multiplex communication device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 arithmetic unit 2 short code RAM 3 input signal 4 long code generation circuit 5 synthesis circuit 21 arithmetic circuit 22 counter 23 data bus 24 read address 25 write address 26 switch 27 short code RAM 28 short code output 31 transmission information 32 Address designating circuit 34 Memory 36 D / A converter 37 Code division multiplex signal 38 Address control signal

Claims (7)

[Claims] 1. An arithmetic unit for calculating a spread code of each channel, and a storage unit for storing the spread code calculated by the arithmetic unit, wherein an input signal of each channel is stored in the storage unit. A spread-spectrum code generator, which is spread by a code sequence, thereby eliminating the need for a spread-code generation circuit for each channel. 2. The spread-spectrum code generator according to claim 1, wherein the phase shift between the respective channels is eliminated. 3. The spread spectrum apparatus according to claim 1, wherein a read address for reading a spread code stored in said storage section is generated by an output of the same counter for a plurality of channels. Code generator. 4. The method according to claim 1, wherein only the spreading code is generated by the storage unit, and the operation of the amplitude value information for power control is performed separately from the spreading with the code read from the storage unit. Item 2. A spread spectrum code generator according to item 1. 5. A switch for switching between a write address and a read address for the storage unit for storing a spread code of each channel, wherein the switch reads a channel spread code from the storage unit.
2. The apparatus according to claim 1, wherein a specific spread code can be written. 6. A calculating means for calculating a spreading code of each channel of a plurality of channels in advance, a storage unit for accumulating the spreading code calculated by the calculating means as a short code for each channel, and a predetermined attribute code. Code generating means for generating, the input signal of each channel is spread by the spread code sequence read from the storage unit, and further spread by the code generating means, the spread signal A spread-spectrum code generator, which performs addition and subtraction based on channel amplitude values and outputs a spread-synthesized output. 7. A switch unit for switching between the write address and the read address, wherein a write address of the storage unit uses an address signal output from the arithmetic unit, a read address of the storage unit uses a counter output, and 7. The spread spectrum code generator according to claim 6, wherein said switch means switches to a write side when a write address is output from said arithmetic means.