JP2001326589A - Spread code generator and spread code generating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spread code generator and a spread code generating method by which interception of contents of transmission data can be prevented without identification of a pattern of frequency information even after interception of the frequency information being a random spread code. SOLUTION: A time counter 2 gives a revision instruction to an M sequence code generator 3 and a frequency table 4 at a revision time designated by revision time information, the M sequence code generator 3 revises and sets an M sequence stage number and an M sequence feedback tap on the basis of stage number information and feedback tap information to revise an M sequence code, and the frequency table 4 revises and sets the frequency information corresponding to an address on the basis of address and frequency information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread code generator and a spread code generation method, and more particularly to a spread code generator and a spread code generator using a noise code in a radio transmission apparatus using frequency hopping as a spread spectrum modulation method. About the method.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing the configuration of a conventional spread code generator and a table showing the contents of a conventional frequency table. FIG. 5 explains the operation of the conventional spread code generator. FIG.

As shown in FIG. 4, a conventional spread code generator includes a frequency hopping clock generator 1 and a conventional M code.
A sequence code generator 12 and a conventional frequency table 13 are used. The frequency hopping clock from the frequency hopping clock generator 1 shown in FIG.
The M-sequence pseudo-noise code shown in FIG. 5 is output from the sequence code generator 12, and frequency information is extracted from the conventional frequency table 13 using the M-sequence pseudo-noise code as an address.
The pseudorandom frequency information (spreading code) shown in FIG.

[0004]

In the prior art, however, pseudo-random frequency information (spreading code) is generated by using an M-sequence pseudo-noise code as an address from which frequency information is read. As shown, the frequency information of the conventional frequency table 13 is arranged and fixed in a series of orders, and the M sequence in the conventional M-sequence code generator 12 is also fixed. ) Is repeated for each M-sequence cycle as shown in FIG. 5, and only randomness equivalent to the M-sequence pseudo-noise code can be obtained, and frequency information for the M-sequence cycle is once clarified. In addition, there is a problem that the contents of transmission data after that are intercepted.

The present invention has been made in view of such a problem, and an object of the present invention is to specify a pattern of subsequent frequency information even when frequency information which is a random spreading code is intercepted. Another object of the present invention is to provide a spread code generating apparatus and a spread code generating method capable of preventing transmission data contents from being intercepted without being transmitted.

[0006]

Means for Solving the Problems In order to solve the above problems, the present invention has the following constitution. The gist of the invention according to claim 1 is a spread code generator that generates an M-sequence code, and outputs the corresponding frequency information as a random spread code using the M-sequence code as an address. And an M-sequence code generating means for generating the M-sequence code changed in response to a change instruction from the change instructing means. The gist of the invention according to claim 2 is that the change instructing means instructs the change of the M-sequence code based on change time information in which a change time is determined. Resides in the code generator. The gist of the invention according to claim 2 is that the M-sequence code generation means changes the number of stages of a shift register used to generate the M-sequence code according to the change instruction from the change instruction means, and 2. A modified M-sequence code is generated.
Or the spread code generator according to item 2. Claim 4
The gist of the invention described is that the M-sequence code generation means changes a feedback tap from the shift register used to generate the M-sequence code according to the change instruction from the change instruction means, and the arrangement is changed. The spread code generator according to any one of claims 1 to 3, wherein the generated M-sequence code is generated. Claim 5
The gist of the present invention includes a frequency table for changing the frequency information corresponding to the address in accordance with the change instruction from the change instruction means. The spread code generator exists. The gist of the invention according to claim 6 is a spread code generating method for generating an M-sequence code and outputting corresponding frequency information as a random spread code using the M-sequence code as an address, The present invention is directed to a spread code generating method, characterized by instructing a change, and generating the changed M-sequence code according to the change instruction. Claim 7
The gist of the present invention resides in a spread code generating method according to claim 6, wherein an instruction to change the M-sequence code is issued based on change time information in which a change time is determined. The gist of the invention according to claim 8 is characterized in that, in accordance with the change instruction, the number of stages of a shift register used to generate the M-sequence code is changed, and the M-sequence code whose cycle is changed is generated. A spread code generating method according to claim 6 or 7 is provided. The gist of the invention according to claim 9 is that, in accordance with the change instruction, a feedback tap from the shift register used for generating the M-sequence code is changed to generate the M-sequence code whose arrangement is changed. A spread code generating method according to any one of claims 6 to 8, wherein The gist of the invention described in claim 10 is:
10. The spread code generating method according to claim 6, wherein the frequency information corresponding to the address is changed according to the change instruction.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an embodiment of a spread code generator according to the present invention. FIG. 2 is an explanatory diagram for explaining a configuration of an M-sequence code generator shown in FIG. FIG. 3 is a diagram showing an example of change time information, an example of the number of stages, an example of feedback tap information, and an example of address / frequency information stored in the external memory shown in FIG.

In this embodiment, a clock generator for frequency hopping 1 generates a clock for frequency hopping.
A time counter 2 for counting time; an M-sequence code generator 3 for generating and outputting an M-sequence code which is an M-sequence pseudo-noise code; and an M-sequence code from the M-sequence code generator 3 as an address. A frequency table 4 containing frequency information corresponding to the address, an external memory 5 storing time counter 2, an M-sequence code generator 3, and various information input to the frequency table 4. Frequency information, which is a random spread code, is output from the frequency table 4 using the M-sequence pseudo-noise code output from the sequence code generator 3 as an address.

The time counter 2 stores the change time information input from the external memory 5 and sends a change instruction to the M-sequence code generator 3 and the frequency table 4 at the change time specified by the stored change time information. Do.

An M-sequence code generator 3 converts an M-sequence, that is, a (2 @ N -1) -sequence code whose check polynomial is a primitive polynomial in a cyclic code into an N-stage linear feedback type shift register. A1 generates and outputs using A1 to AN, stores the stage number information and feedback tap information input from the external memory 5, and based on the stage number information and feedback tap information in response to a change instruction from the time counter 2. Then, the number of M-sequence stages and the M-sequence feedback tap are changed and set, and the M-sequence code is changed.

The number of stages of the M-sequence in the M-sequence code generator 3 is set by setting the number of stages of the shift registers A1 to AN used for generating the M-sequence code to a different number of stages by designating the number-of-stages information. It means to change, and is set by changing the return position. For example, when the number of stages N of the M sequence is designated as 5 by the information on the number of stages of the M sequence, the setting is made so that the feedback is performed in five stages of the shift registers A1 to A5. When the number N of stages of the designated M sequence is changed from 5 to 8, the setting is made so that the feedback is performed in eight stages of shift registers A1 to A8. In FIG. 2, an arrow R fed back to the shift register AN indicates a feedback position. Also,
The setting of the number of stages of the shift registers A1 to AN used to generate the M-sequence code can be performed by a method realized by hardware or a method realized by software.

The setting of the M-sequence feedback tap in the M-sequence code generator 3 is performed by changing the output to be fed back among the outputs A1 to AN from the respective stages of the shift registers A1 to AN by designating the feedback tap information. This means that the arrangement of the M series is changed, and among the feedback taps T1 to TN corresponding to the respective stages of the shift registers A1 to AN, “1” is defined as the feedback tap of the stage to be fed back, and "0" is defined for the feedback tap of the stage to be disabled, and the output A1
It is configured to take an AND with the AN, take the EXOR of each term, and feed it back. In FIG. 2, arrows D1 to DN indicate initial values given to the shift registers A1 to AN.

The frequency table 4 stores address / frequency information input from the external memory 5 and changes and sets frequency information corresponding to an address based on the address / frequency information in response to a change instruction from the time counter 2. I do.

The external memory 5 stores change time information input to the time counter 2, stage number information and feedback tap information input to the M-sequence code generator 3, and address / frequency information input to the frequency table 4. ing. The change time information is information for specifying a change time as shown in FIG. 3, and the stage number information indicates the number of stages, that is, the number of stages of the shift registers A1 to AN used for generating the M-sequence code as shown in FIG. As shown in FIG. 3, the feedback tap information is information specified by each feedback tap, that is, the feedback taps, that is, the feedback taps corresponding to the shift registers A1 to AN are defined as “1” or “0”. Information that specifies the output of the stage to be fed back among the outputs A1 to AN from each stage of the registers A1 to AN for each change time,
The address / frequency information includes an address as shown in FIG.
That is, it is information that specifies frequency information corresponding to the M-sequence code from the M-sequence code generator 3 for each change time. The address / frequency information is configured using a noise code generated by thermal noise or the like.

Next, the operation of the embodiment will be described in detail.

First, the time counter 2 is read from the external memory 5.
, The stage number information and the feedback tap information to the M-sequence code generator 3, and the address / frequency information to the frequency table 4.

Based on the input from the external memory 5, the change time information is stored in the time counter 2, the stage number information and the feedback tap information are stored in the M-sequence code generator 3, and the address / frequency information is stored in the frequency table 4.

The time counter 2 counts the time and issues a change instruction to the M-sequence code generator 3 and the frequency table 4 each time the change time specified in the change time information is reached. Changes and sets the number of M-sequence stages based on stage number information according to a change instruction from the time counter 2 and changes and sets the M-sequence feedback tap based on feedback tap information. According to the change instruction from the counter 2, the frequency information corresponding to the address is changed and set based on the address / frequency information.

The change time information as shown in FIG. 3 is stored in the time counter 2, the stage number information and the feedback tap information are stored in the M-sequence code generator 3, and the address / frequency information is stored in the frequency table 4.
, The time counter 2 instructs the M-sequence code generator 3 and the frequency table 4 to change at time 0:00.

The M-sequence code generator 3 sets the number of M-sequence stages to nine in response to a change instruction from the time counter 2, and sets M-sequence feedback taps, ie, feedback taps T1 to T
9, T1 = 1, T2 = 0, T3 = 1, T4 = 0, T5
= 1, T6 = 1, T7 = 0, T8 = 1, T9 = 1, and the time hopping clock generator 1 uses the frequency hopping clock 1 until the next change instruction is issued from the time counter 2. Generate and output an M-sequence code by setting.

In response to a change instruction from the time counter 2, the frequency table 4 has address 1 = frequency information F1, 2 =
Frequency information F2, 3 = Frequency information F3, 4 = Frequency information F4, 5 = Frequency information F5... Until the next change instruction is issued from the time counter 2, the M-sequence code generator 3 Using the M-sequence code as an address, frequency information corresponding to the address is read, and frequency information that is a random spreading code is output.

Next, the time counter 2 issues a change instruction to the M-sequence code generator 3 and the frequency table 4 at time 0:22, and the M-sequence code generator 3 The number of M-sequence stages is set to 12, and M-sequence feedback taps, that is, feedback taps T1 = 0,
T2 = 0, T3 = 1, T4 = 0, T5 = 0, T6 = 1,
T7 = 1, T8 = 0, T9 = 1, T10 = 1, T11 =
0, T12 = 1, and the M-sequence code is generated and output by the frequency hopping clock from the frequency hopping clock generator 1 until the next change instruction from the time counter 2 is generated.

The frequency table 4 has an address 1 = frequency information F4, 2 =
Frequency information F3, 3 = frequency information F8, 4 = frequency information F11, 5 = frequency information F23... Until the next change instruction is issued from the time counter 2, the M-sequence code generator 3 Using the M-sequence code as an address, frequency information corresponding to the address is read, and frequency information that is a random spreading code is output.

Hereinafter, the time counter 2 reads the time 0:37,
A change instruction is issued to the M-sequence code generator 3 and the frequency table 4 every 1:02..., And the settings of the M-sequence code generator 3 and the frequency table 4 are similarly changed.

When the present embodiment is used in an actual wireless transmission device, the configuration of the present embodiment is provided in each of the wireless transmission device serving as a master station and the wireless transmission device serving as a slave station. By making each piece of information stored in the memory 5 the same, synchronization can be achieved by the time counter 2. Therefore, the frequency information (spreading code) of the master station and the slave station match, and the radio using frequency hopping is used. Transmission becomes possible.

As described above, according to the present embodiment, the setting of the number of stages of the M-sequence, the feedback tap of the M-sequence and the setting of the frequency information are made variable and changed and set according to the time information. Even when the frequency information that is a spread code is intercepted, the periodicity changes with time, so that the pattern of the subsequent frequency information is not specified, and the spread when outputting the frequency information that is a random spread code is performed. This has the effect of increasing the randomness of the code and preventing the transmission data content from being intercepted.

It should be noted that the present invention is not limited to the above embodiments, and each embodiment can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, but can be set to numbers, positions, shapes, and the like suitable for carrying out the present invention. In the drawings, the same components are denoted by the same reference numerals.

[0029]

The spread code generator and the spread code generation method of the present invention vary the number of stages of the M sequence, the feedback tap of the M sequence and the frequency information, and change and set the time information. Even when frequency information that is a random spreading code is intercepted, the periodicity changes depending on time, so that the pattern of the subsequent frequency information is not specified, and the frequency information that is a random spreading code is output. Has an effect that the randomness of the spread code can be increased, and interception of transmission data contents can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a spreading code generator according to the present invention.

FIG. 2 is an explanatory diagram for describing a configuration of an M-sequence code generator shown in FIG.

FIG. 3 is a diagram showing an example of change time information, an example of stage number information, an example of feedback tap information, and an example of address / frequency information stored in the external memory shown in FIG.

FIG. 4 is a block diagram showing a configuration of a conventional spread code generator and a table showing the contents of a conventional frequency table.

FIG. 5 is a timing chart for explaining the operation of a conventional spread code generator.

[Explanation of symbols]

 Reference Signs List 1 clock generator for frequency hopping 2 time counter 3 M-sequence code generator 4 frequency table 5 external memory A1 to AN shift register T1 to TN feedback tap

Claims (10)

[Claims] 1. A spread code generator for generating an M-sequence code and outputting corresponding frequency information as a random spread code using the M-sequence code as an address, comprising: a change instruction for instructing a change of the M-sequence code. Means for generating the changed M-sequence code in response to a change instruction from the change-instruction means. 2. The spread code generating apparatus according to claim 1, wherein said change instructing means instructs to change said M-sequence code based on change time information in which a change time is determined. 3. The M-sequence code generator, wherein the M-sequence code generation means changes the number of stages of a shift register used to generate the M-sequence code in accordance with the change instruction from the change instruction means, and 3. The spread code generator according to claim 1, wherein the code is generated. 4. The M-sequence code generation means changes a feedback tap from the shift register used to generate the M-sequence code according to the change instruction from the change instruction means, and changes the arrangement. 4. The spread code generator according to claim 1, wherein the M-sequence code is generated. 5. The spread code according to claim 1, further comprising a frequency table for changing the frequency information corresponding to the address in accordance with the change instruction from the change instruction unit. Generator. 6. A spread code generating method for generating an M-sequence code and outputting the corresponding frequency information as a random spread code using the M-sequence code as an address, wherein a change of the M-sequence code is instructed. A method for generating a spread code, comprising generating the changed M-sequence code according to a change instruction. 7. The spread code generating method according to claim 6, wherein a change of the M-sequence code is instructed based on change time information in which a change time is determined. 8. The method according to claim 1, wherein the change instruction changes the number of stages of a shift register used to generate the M-sequence code,
8. The spread code generating method according to claim 6, wherein said M-sequence code having a changed cycle is generated. 9. The method according to claim 6, wherein a feedback tap from the shift register used to generate the M-sequence code is changed in accordance with the change instruction, and the M-sequence code whose arrangement is changed is generated. 9. The method according to any one of claims 1 to 8, wherein 10. The spread code generating method according to claim 6, wherein the frequency information corresponding to the address is changed according to the change instruction.