KR100273048B1 - Method for generating spread code having orthogonality - Google Patents

Abstract

A spreading code generation method having an orthogonal characteristic is disclosed. The method includes the steps of receiving an input symbol, generating an exclusive sub-order of an odd number of selected odd bits among the input symbols, and generating an SX code using all possible odd-numbered Ex-OR subcodes. Generating and spreading the input data using the SX code. SX code S in the form of P × P matrix according to the present invention,

Represented by F _i (*) Is the input bit X ₁ To X _N This is a sub code in which the selected odd number of bits is Ex-OR. This method reduces the timing required for code generation by generating SX codes having orthogonal characteristics such as Walsh codes or Hadamard codes using only Ex-OR logic without using additional control logic. This has the effect of generating code.

Description

Spreading Code Generation Method with Orthogonal Characteristics

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread code generation method for spread spectrum communication, and in particular, a mobile telephone or a base station using code division multiple access (CDMA) technology. The present invention relates to a spreading code generation method having an orthogonal characteristic for distinguishing user channels and maintaining orthogonality of codes in a base station.

The code division multiple access system multiplies its own spread code and spreads the band on one frequency before transmitting signals of each subscriber using a common frequency. When receiving, despreading is performed first, and each signal is distinguished by multiplying by the same code as in transmitting. Code division multiple access systems use spreading bands to increase the efficiency of use of frequencies and to support encryption using codes.

In a code division multiple access system, a channel from a base station to a radio terminal is called a forward link, and a channel from a terminal station to a base station is called a reverse link. In the forward link, a base station distinguishes channels by multiplying a signal transmitted from a mobile switching center by a pseudorandom noise code (PN code) having orthogonality. The mobile phone also uses spreading codes on the reverse link to maintain orthogonality between a number of input data.

In general, a mobile phone or a base station using a code division multiple access technique uses a Walsh code or a Hadamard code as a spreading code having an orthogonal characteristic. In order to generate Walsh codes or Hadamards in a short time while maintaining the orthogonality according to the input signal, the diffusion code generation method according to the prior art uses fast Hadamard Coding.

1 shows an embodiment of a Hadamard code generation method according to the prior art, and as shown, a counter 110 for generating 4-bit outputs A0 to A3 by a clock; A buffer 120 that receives a 2-bit input signal and generates a 4-bit output B0 to B3 according to a predetermined rule; A control logic 130 for controlling the output of the buffer; Four AND gates 140, 142, 144, 146 and the four AND gates that AND the output signals A0 to A3 of the counter and the output signals B0 to B3 of the buffer, respectively. Is composed of an Ex-OR gate 150 that generates an output by performing an exclusive OR on the output of the.

The buffer 120 selectively outputs 4-bit output signals B0 to B3 by control logic. Examples of 4-bit outputs for 2-bit inputs are shown in Table 1 below.

input Print B0 B1 B2 B3 0 0 0 0 0 0 0 One 0 One 0 One One 0 0 0 One One One One 0 One One 0

A base station or mobile telephone of a code division multiple access system distinguishes each channel by multiplying a predetermined row for each channel. For example, the pilot channel is assigned the first row.

In the spreading code generation method according to the prior art operating as described above, since the control logic and the buffer for controlling the orthogonal code generated for the input are required, the code generation takes a long time, and the row generated for the input is generated. There is a problem in that the circuit configuration is complicated because a memory resource to store the data is required.

Accordingly, an object of the present invention, which is designed to solve the problems of the prior art operating as described above, is to use a sub-combination Ex-OR having orthogonal characteristics using purely Ex-OR logic without using additional control logic. It is to provide a spreading code generation method having an orthogonal characteristic for generating a Subset Ex-OR (SX) code.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention and the accompanying drawings.

1 is an embodiment of a Hadamard code generation method according to the prior art.

2 is a method for generating SX orthogonal code according to the present invention.

3 is a fourth order SX orthogonal code generation method according to the present invention;

4 is an SX code in the form of an 8x8 matrix in accordance with the present invention.

5 is an SX code in the form of a 2x2 matrix output by a 2-bit input.

6 is an SX code in the form of a 4x4 matrix output by a 3-bit input.

7 is an SX code of 8x8 matrix form output by 4 bit input.

8 is an SX code of 16x16 matrix form output by a 5-bit input.

<Explanation of symbols for the main parts of the drawings>

110: counter 120: buffer

130: control logic 140,142,144,146: logical gate

150: Exclusive-OR gate

210,220,230,240,250,260,310,320,330,340,350,360,370,380

245,255,265,355,365,375,385: exclusive OR logic

A preferred embodiment of the method for generating a spreading code having an orthogonal characteristic according to the present invention, which is designed to achieve the above object,

Receiving an input symbol;

Generating a sub-code exclusive of the odd bits selected from the input symbols (Ex-OR); And

Generating an SX code using all possible odd-numbered Ex-OR subcodes.

Another preferred embodiment of the spreading code generation method having an orthogonal characteristic according to the present invention,

Receiving an input symbol;

Generating a sub-code exclusive of the odd bits selected from the input symbols (Ex-OR);

Generating an SX code using all possible odd Ex-OR subcodes; And

And spreading the input data using the SX code.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification. Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention.

The present invention generates a spreading code having orthogonality in a spreading code used for spreading data in a communication system. According to the present invention, when a spreading code having an orthogonal characteristic is called an SX code, an SX orthogonal code having a span N is implemented as in Equation (1).

Where span N is the window size in the inputable binary domain, X Is an N-bit binary type signal included in the window. F _i (*) Is the i th Ex-OR subcode, P Is the number of Ex-OR subcodes P = 2 ^N-1 to be.

2 shows an embodiment of the SX orthogonal code generation method according to the present invention. As shown, the SX orthogonal code includes all possible odd Ex-OR subcodes F (*) Ex-OR logic 245, 255, 265 for outputting &lt; RTI ID = 0.0 &gt; and &lt; / RTI &gt; Is generated. Each memory element is P, i-th memory element F _i (*) Save it.

P = 2 ^N-1 When the orthogonal code generated by the SX code, as shown in equation (2) P × P It is created as a matrix.

As shown in equation (2), the j th SX code SX _j Is P × P J-th row of the matrix. A communication system for spreading data using a spreading code is P × P Assign one row of the matrix to one channel. Therefore, the communication system can distinguish up to P channels.

Hereinafter, a fourth order SX code for generating an orthogonal code having span N = 4 and P = 8 will be described. An orthogonal code with N = 4 and P = 8 is generated by equation (3) and implemented as shown in FIG.

=

The SX code in the form of an 8 × 8 matrix generated by Equations 3 and 2 is shown in FIG. 4.

Hereinafter, orthogonal characteristics of the SX code with span N = 4 will be described. If the values of the SX code satisfy Equation 4, the code has orthogonality. Where symbol Outputs 1 if the two inputs are equal and -1 if they are different.

= P , only j = k

here X ^j Denotes the decimal number j in N-bit binary form. For example, if the values of i and j are 5 and 6, respectively X ⁵ = (0,1,0,1), X ⁶ = (0,1,1,0), so SX ₅ Wow SX ₆ Equation 4 is calculated as in Equation 5.

That is, common code values (code lines) produced by SX codes maintain orthogonality with each other. Also from FIG. 3 X ⁰ , X ¹ , X ² , X ³ , X ⁴ , X ⁵ , X ⁶ , X ⁷ Are each X ¹⁵ , X ¹⁴ , X ¹³ , X ¹² , X ¹¹ , X ¹⁰ , X ⁹ , X ⁸ It can be seen that it is in inverse relationship with.

FIG. 5 is a 2x2 matrix generated by SX orthogonal code using 2 bit input, FIG. 6 is a 4x4 matrix generated by SX orthogonal code using 3 bit input, and FIG. 7 is a 4bit input. Is an 8x8 matrix generated by the SX orthogonal code using &lt; RTI ID = 0.0 &gt; and &lt; / RTI &gt; FIG. 8 is a 16x16 matrix generated by the SX orthogonal code using 5-bit input. As shown in Figs. 5 to 8, the SX orthogonal code generates a matrix that satisfies all orthogonal characteristics expressed by double.

That is, the SX orthogonal code is composed of a sub code obtained by Ex-ORing selected odd bits among the input bits.

Therefore, by applying the SX orthogonal code as described above to a code division multiple access system, a spreading code having orthogonality can be generated using a simple structure using only Ex-OR logic.

The present invention can be variously modified and can take various forms and only the specific embodiments thereof are described in the detailed description of the invention. It is to be understood, however, that the present invention is not limited to the specific forms mentioned in the detailed description of the invention, but rather includes all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. It should be understood to do.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention reduces the timing required for code generation by generating SX codes having orthogonal characteristics such as Walsh codes or Hadamard codes using only Ex-OR logic without using additional control logic. This has the effect of generating code. In addition, by applying the SX code to the code division multiple access system, it is possible to reduce the time required to generate the code in the system, simplify the structure of the system, and increase the efficiency of the system.

Claims (5)

Receiving an input symbol; Generating a sub-code exclusive of the odd bits selected from the input symbols (Ex-OR); And Generating an SX code using all possible odd-numbered Ex-OR subcodes. The method of claim 1, wherein the generating of the SX code comprises: N is the number of bits in the input symbol, P is N-1 square of 2, X ^j Is the jth input symbol representing the decimal number j in binary, F _i (*) Is the i th Ex-OR subcode, The SX code S in the form of a P × P matrix generated by the input symbol is Spreading code generation method having an orthogonal characteristic, represented by. The method of claim 2, j input symbol X ^j Is the input bit X ₁ To X _N When expressed by remind F _i (*) Is the input bit X ₁ To X _N A method of generating a spreading code having an orthogonal characteristic, which is a sub code obtained by ex-oring selected odd bits among them. The method of claim 2, sign When we define a as a symbol that outputs 1 if the two inputs are equal and -1 if it is different, Any SX code above SX _j Wow SX _k Is, j ≠ k Back side Satisfying, j = k Back side Spreading code generation method having an orthogonal characteristic that satisfies. Receiving an input symbol; Generating a sub-code exclusive of the odd bits selected from the input symbols (Ex-OR); Generating an SX code using all possible odd Ex-OR subcodes; And And spreading the input data using the SX code.