CN1555615A - Encoding method for product complemenbary code, checking method and checking device - Google Patents

Encoding method for product complemenbary code, checking method and checking device Download PDF

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CN1555615A
CN1555615A CNA028181220A CN02818122A CN1555615A CN 1555615 A CN1555615 A CN 1555615A CN A028181220 A CNA028181220 A CN A028181220A CN 02818122 A CN02818122 A CN 02818122A CN 1555615 A CN1555615 A CN 1555615A
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code
integrator
adder
real part
imaginary part
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沈东栋
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Linkair Communications Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/10—Code generation
    • H04J13/102—Combining codes
    • H04J13/107—Combining codes by concatenation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/0055—ZCZ [zero correlation zone]

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Abstract

The present invention provides the coding method, checking mehtod and checking device of complementary product code. The complementary product code features that any oe of the complementary product code consists of C code and S code, and both the C code and the S code are complex number in the equal code length and have protecting interval in between. The codnig method can provide more address codes for CDMA system to use while preserving the zero correlative window characteristic. The checking method and the checking device formed on the checking method are used specially in the checking of the zero correlative window characteristic of the code word.

Description

Encoding method for product complemenbary code, checking method and checking device
The invention belongs to the technical field of communication, and particularly relates to a multiple access coding technology suitable for a spread spectrum and Code Division Multiple Access (CDMA) wireless communication system, in particular to a product complementary code coding method, a verification method and a face correction device. Background
Since the frequency band resource is very limited, it has become a very urgent problem to improve the frequency band utilization rate of wireless communication. The term "frequency borrowing efficiency" is generally defined as the total signaling rate per unit bandwidth that can be provided, and when applied to cellular communications, the unit of measurement should be considered within a region reuse range, i.e., the total signaling rate per unit bandwidth that can be provided by a cell or a sector. The higher the spectral efficiency, the larger the capacity of the system.
A Code Division Multiple Access (CDMA) communication system is a self-interference system that is limited by a signal-to-interference ratio relative to Frequency Division Multiplexing (FDMA) and Time Division Multiplexing (TDMA). Increasing the number of users served by the system means an increase in interference, thereby reducing the quality of service of the system. From the source of interference, there are four main categories: intersymbol interference (ISI), Multiple Access Interference (MAI), Adjacent Cell Interference (ACI) and local and system internal noise. The purpose of address coding is to eliminate the first three kinds of interference as much as possible, which requires that the address codes of each user should be orthogonal to each other. An ideal multi-access code should have ideal auto-and cross-correlation properties, i.e. a zero peak everywhere (a peak is an auto-correlation value and a cross-correlation value for each point except the origin). The Welch's kingdom (ref: L.R Welch, Lower bones On the maximum cross correlation of signals, IEEE trans. On Information Theory, Vol. IT-20, pp. 397-399, 1974), published in 1974, demonstrated that within a limited i or complex field, ideal codewords for the relevant properties were not present. This theoretical boundary indicates that the auto-correlation property and the cross-correlation property of the sequences are a pair of contradictions, and that good auto-correlation property inevitably leads to poor cross-correlation property, and vice versa.
In international application No.: PCT/CN 00/00028, inventors: the invention relates to a plum-leaf invention, which has the following name:
in the invention patent application of 'a spread spectrum multiple access coding method with zero correlation window', the idea of 4 of the zero correlation window is proposed for the first time, namely, the correlation function between address codes has no peak in the maximum time diffusion quantity of a channel, so that intersymbol interference (ISI) and Multiple Access Interference (MAI) are not generated, and the 'near-far effect' is avoided. Some theoretical results generated by Welch' however demonstrate that the number of codewords having the zero correlation window characteristic for a given length is in an inverse relationship with the zero correlation window length, and that the product of the zero correlation window length and the number of codewords is substantially equal to the code length. For Code Division Multiple Access (CDMA) wireless communication systems, an increase in the number of available codewords directly leads to an increase in system capacity, thereby increasing the frequency i-p efficiency of the system. Therefore, finding a larger number of codewords with good correlation properties becomes an important issue in the field of address coding.
In the above patent application, the inventor has found that the zero correlation window-LS code provided by the original is extended based on the basic code having complementary characteristics, which are additive. If it is transplanted in a multiplicative complementary sense, can one set of codewords with better correlation properties be used to balance another set of codewords with poorer correlation properties? Is it ideal for any one of the two sets of correlation properties to necessarily ensure that the entire correlation properties are also ideal due to the multiplicative relationship? If more orthogonal codewords with zero correlation window characteristics can be constructed in this way, how do the zero correlation window characteristics of these new codewords correct ^ r.
Disclosure of Invention
The present invention provides a method for encoding a product complementary code, a method for checking the product complementary code, and a device for checking the product complementary code, wherein the product complementary code can provide a larger number of address codes for a system to use on the basis of keeping the characteristic of a zero correlation window. The check device is formed by a check method, and the check method and the check device are specially used for checking the zero correlation window characteristic of the code word.
The object of the invention is achieved by a method and a device as follows:
a coding method of product complementary code is characterized in that any product complementary code is composed of C code and S code; the C code and the S code are complex numbers and have the same code length; there is a guard interval between the C code and the S code.
Any product complementary code is composed of a C code and an S code, and the product complementary code is characterized in that: any one of the product complementary codes is composed of a C code and an S code.
The C code and the S code are complex numbers, and the equal code length means that: the real part and the imaginary part of the C code are completely the same; the real part and imaginary part sequences of the S code satisfy the addition complementary condition, namely the real part and the imaginary part of the S code are respectively regarded as the C code and the S code of the LS code.
The guard interval between the C code and the S code is as follows: the guard interval between the C and S codes consists of all zeros.
The method for encoding the product complementary code comprises the following steps: c codes and S codes are adopted to form product complementary codes, and any product complementary code consists of a C code and an S code; making the real part and the imaginary part of the C code identical; the real part sequence and the imaginary part sequence of the S code meet the addition complementary condition, namely the real part sequence and the imaginary part sequence of the S code are respectively regarded as the C code and the S code of the LS S code; a guard interval is arranged between the C code and the S code, and the guard interval between the C code and the S code is composed of all zeros.
A method of encoding for multiplication, the steps further comprising: is two in [ -L +1, L-1 [ -L + ]]Having ideal correlation features within the window
Figure IMGF000005_0001
The product of the nature of the complementary codes, c,<microspheres, representing the real and imaginary parts of the 1 st code words C and S, respectively, and having code lengths L, C2, cQ L 2sj2-, respectively representing the real and imaginary parts of the 2 nd codeword C and S codes; then on the basis of these two codewords, the coding results in 4 2L long and has the following ideality:
Figure IMGF000005_0002
it is possible to expand the code word with the same ideal correlation characteristic to have a longer code length according to this condition. A method for checking product complementary codes is characterized in that: the correlation property of any product complementary code composed of the C code and the S code needs to satisfy the following condition:
R(i, j, k) =
Figure IMGF000005_0003
LrL
here i ^ m, ί ή ^ (+ i ή, the ^ a, < the ^ a >, < the original pattern >, < the microspheres (^ a >, < the original pattern >) = microspheres (/ + microspheres 5; (/), C ^ a);(/), S, (/) denote the second
1= 0/7 th chip of the C code and S code of the product complementary code, denotes a conjugate, Re () denotes a real part, A6 ', J;) represents a correlation value of the/th codeword and the J ' th codeword delayed by one chip, which is an autocorrelation characteristic when/= J '.
The sum RrM in the conditions described, can be opened to yield:
j, k) = (RC[I(Ζ·, k) + RCqqii, k) )' [RS„ ( j, k) + RSqq(i, j, k) )
+ (RCg!(!·, k) - RClQ(i, j, k) j. (z, j, k)― RSlQ(i, j, k) )
where the subscripts/and divisions of the c-code and s-code represent the in-phase and quadrature components of the complex code; the correlation characteristics of the product complementary code can be controlled by four correlation amounts in the above equation.
An apparatus for checking product complementary codes, comprising: serial-parallel conversion device, correlator, adder and multiplier',
the in-phase component and the orthogonal component Q of the product complementary code are input into the serial-parallel conversion device; the output of the serial-parallel conversion device is the input of the correlator;
the output of the correlator is the input of the adder;
the output of the adder is the input of the multiplier;
the output of the multiplier is the input of another adder, and the output of the adder is the correlation characteristic quantity R (i, j, k) of the product complementary code.
The correlator may be constituted by an integrator.
The integrators are integrators related to the real part of the C code, integrators related to the imaginary part of the C code, integrators related to the real part of the S code and integrators related to the imaginary part of the S code.
The checking device for product complementary codes comprises: the serial-parallel conversion device comprises an integrator related to a real part of the C code, an integrator related to an imaginary part of the C code, an integrator related to a real part of the S code, an integrator related to an deficiency-type part of the S code, an adder and a multiplier;
the in-phase component/of the product complementary code is input to the serial-parallel conversion device (1), and the orthogonal component Q of the product complementary code is input to the serial-parallel conversion device (2); the output of the serial-parallel conversion device (1) is respectively the input of an integrator (3) related to the real part of the C code, an integrator (4) related to the imaginary part of the C code, an integrator (7) related to the real part of the S code and an integrator (8) related to the imaginary part of the S code;
the output of the serial-parallel conversion device (2) is the input of an integrator (5) related to the imaginary part of the C code, an integrator (6) related to the real part of the C code, an integrator (9) related to the imaginary part of the S code and an integrator (10) related to the real part of the S code respectively; '
The output of the integrator (3) about the real part of the C code and the integrator (5) about the imaginary part of the C code are the input of the adder (11);
the output of the integrator (4) about the imaginary part of the C code and the integrator (6) about the real part of the C code are the input of the adder (12);
the output of the integrator (7) about the real part of the S code and the integrator (9) about the imaginary part of the S code are the input of the adder (13);
the output of the integrator (8) related to the S virtual code part and the integrator (10) related to the S code real part are the input of the adder (14);
the outputs of the adder (11) and the adder (13) are the inputs of the multiplier (15);
the outputs of the adder (12) and the adder (14) are the inputs of the multiplier (16);
the outputs of the multiplier (15) and the multiplier (16) are the inputs of the adder (17);
the output of the adder (17) is the correlation characteristic quantity R (I, j, k) of the product complementary code.
The invention has the beneficial effects that by providing the encoding method, the checking method and the checking device of the product complementary code, more address codes are provided for the system to use on the basis of keeping the zero correlation window characteristic of the code word. The provided checking method and the checking device accurately check the zero correlation window characteristic of the code word, so that the ideal zero correlation window characteristic of the new code word is ensured. For Code Division Multiple Access (CDMA) wireless communication systems, the present invention allows an increase in the number of codewords with good correlation properties, which directly results in an increase in system capacity, thereby increasing the frequency efficiency of the system.
Drawings
Fig. 1 is a block diagram of the apparatus according to the present invention.
Detailed Description
Firstly, the structure of the product complementary code of the invention is given, namely: any one of the code words is composed of a C code and an S code, the C code and the S code are complex codes, the code lengths are equal, a guard interval is arranged between the C code and the S code, and the guard interval is composed of all zeros.
The invention also provides a checking method and a checking device of the product complementary code, which are shown in figure 1. The device can be composed of 8 correlators and a plurality of addition multipliers, and the device complexity is higher than that of a common correlator. The output of this checking device is the product of two complex digital correlation values, whose mathematical expression is:
Figure IMGF000008_0001
(1) Where R toc~cThe microspheres (I, j, k) = Cj (/ + k) C; (/), R — (I, j, k) = Sj (I + k) S (/), Q (/), and the microspheres (/) in the respective values indicate the respective values of the fifth and sixth values
The C code and the S code of the/product complementary code have the first chip of the conjugate, Re () represents the real part, R (i, j, k) represents the correlation value of the first code word and the j code word delayed by k chips, and when i = j, the correlation value is the autocorrelation value.
Expanding Rcc', k) and Rss j, k) to obtain ij
Rcc and
Figure IMGF000008_0002
where the subscripts/and divisions of the C-code and S-code represent the in-phase and quadrature components of the complex code.
Order:
(1)，
Figure IMGF000008_0003
C} J{ k)CQl)
Figure IMGF000009_0001
/=o ;=o
RSLQ(!·， k)=∑ ¾(/ + (/) , RSqi(i, j, k)= £ s{ (/ + k)4 (I) 。
=0 /=0
substituting the above expression into equation (1) yields:
j,k) = (RCN(':, J>k) + RCqq(i, J, k) )· [RSii(i, j,k) + RSQE(!', Λ
+ [RCQI(z'，k)― RcIQ(ζ·' j,k) }· [RsQI( j, k) - RsIQ(|, j, k)) (2) it can be seen that the final correlation function is dominated by only the four correlation values in the above equation. Consider first the example where the C and S code lengths are 1.
++ ++ ++ +A
, (c2,s2) =
、++ +-) ++ ++
Figure IMGF000009_0002
The auto-and cross-correlations of the four codewords are calculated, see tables 1 and 2. : autocorrelation function value of 2-bit long product complementary code
Code pair relative shift IIIII IV
-1 2 0 0 2 0
0 4 4 0 0 16
1 2 0 0 -2 0
( ,¾)&-1 2 0 0 -2 0
(c2,s2) 0 4 4 0 0 16
1 2 0 0 2 0
-1 -2 0 0 2 0
(c3,s3) 0 4 4 0 0 16
1 -2 0 0 -2 0-1 -2 0 0 -2 0
(C4,54) 0 4 4 0 0 16
Cross correlation function value of 1-2002022 bit length product complementary code
Figure IMGF000010_0001
(！ ·, ) , RSlIi ,k RSQQi, ， RCQr( j,k)-RCie(i,j,k) , R¾ftj',W— R¾(' J four correlation function values.
From the above two tables we see that although the correlation properties of both I and IV are not ideal within the [ -1, 1] window, the overall correlation properties are still ideal within the [ -1, 1] window with the help of II and III. The construction method of such product complementary code is given below.
The real and imaginary parts of the (one) cc code must be identical.
The real part and imaginary part sequences of the S code must satisfy the condition of additive complementation, that is, the real part and imaginary part of the S code are regarded as the C code and S code of the LS code, respectively, and refer to the patent "a spread spectrum multi-address coding method with zero correlation window".
We can extend the code word with longer code length and the same ideal correlation property by the following method. Two are assumed to be [ -L + L, L-1 [ -L + ]]Having ideal correlation within the window
Figure IMGF000011_0001
Characteristic product complementary code, c ^, c microspheres, s{And ^ represents the real and imaginary parts of the C code and S code, respectively, of the 1 st codeword, and C code andthe code length of S code is L, ch L, cQ L 2, sh LThe real part and imaginary part of the C code and S code of the 2 nd codeword are represented, respectively. On the basis of the two code words, 4 code words with the length of 2L can be obtained by constructing, and the same ideal correlation characteristic is obtained:
Figure IMGF000011_0004
taking the code taro with L =2 as an example, two code words are selected from the code taro:
〜 〜 + +
Figure IMGF000011_0003
the above expansion method is used to obtain 4 new code words ++++++ -,
++ ++ + - ++
-- + +
+1
、++ —— +— ++
++ + + - +)
、++ ++ +— J
One +
The correlation characteristics between these four codewords are calculated by using the values of the autocorrelation function of the complementary code of the product with bit length of 3 and 4 in tables 3: 4
Figure IMGF000012_0001
Note: due to the symmetry of the autocorrelation function, only the correlation values of positive offsets are calculated, and the correlation values of negative offsets can be obtained symmetrically. TABLE 4 Cross-correlation function values of 4-bit long product complementary codes
Figure IMGF000013_0001
The correlation characteristic of the constructed new code is [ -3, 3 [ -3]Ideally within the window.
If it is only required to maintain orthogonality within the window of-1, a larger number of codewords can be constructed. In addition to the above constructed code words, another 4 code words can be constructed by the following method:
Figure IMGF000014_0001
after calculation, the new 4 code words are still [ -3, 3 [)]The orthogonality is kept in the window, but any one of the code words and any one of the four code words can only be in [ -1, 1 [ ]]The window remains orthogonal. That is, the zero correlation window for these 8 codewords is [ -1, 1 [ ]]. Compared with the condition of [ -1, 1 [)]The window keeps the orthogonal product complementary code with 2 bit length, keeps the length of the zero correlation window unchanged, and can construct code words with 1 time of number.
The product complementary code with longer code length can be extended by the extension method described above.
The invention has the beneficial effects that by providing the encoding method, the checking method and the checking device of the product complementary code, more address codes are provided for the system to use on the basis of keeping the zero correlation window characteristic of the code word. The provided checking method and the checking device accurately check the zero correlation window characteristic of the code word, so that the ideal zero correlation window characteristic of the new code word is ensured. For Code Division Multiple Access (CDMA) wireless communication systems, the present invention allows an increase in the number of codewords with' good correlation properties, which directly results in an increase in system capacity, and thus in the spectral efficiency of the system.
The above specific embodiments are merely illustrative of the present invention and are not intended to limit the present invention.

Claims (10)

  1. Claims to follow
    1. A coding method of product complementary code is characterized in that any product complementary code is composed of C code and S code; the C code and the S code are complex numbers and have the same code length; there is a guard interval between the C code and the S code.
  2. 2. The method of claim 1, wherein any one of the product complements is formed by a C code and an S code: s S any product complement code is composed of a C code and an S code.
  3. 3. The method of claim 1, wherein the C code and the S code are complex codes, and the code length being equal means:
    the real part and the imaginary part of the C code are completely the same;
    the real part and imaginary part sequences of the S code meet the addition complementary condition, namely the real part and the imaginary part of the S code are respectively regarded as the C code and the S code of the LS code.
  4. 4. The method of claim 1, wherein the guard interval between the C code and the S code is: the guard interval between the C and S codes consists of all zeros.
  5. 5. The method of claim 1, comprising the steps of:
    c codes and S codes are adopted to form product complementary codes, and any one product complementary code consists of one C code and one S code;
    making the real part and the imaginary part of the C code identical;
    the real part sequence and the imaginary part sequence of the S code meet the addition complementary condition, namely the real part sequence and the imaginary part sequence of the S code are respectively regarded as the C code and the S code of the LS code;
    a guard interval is arranged between the C code and the S code, and the guard interval between the C code and the S code is composed of all zeros.
  6. 6. The method according to claim 5, further including the step of: is two in [ -L + L, L-1 [ - ]]Having ideal correlation features within the windowComplementary code of sexual product, cQ L iThe real part and the imaginary part of the C code and the S code of the 1 st code word are respectively shown, and the code length of the C code and the S code is L, cf2, sf2Respectively representing the real part and the imaginary part of the C code and the S code of the 2 nd code word; then on the basis of these two codewords, the condition for obtaining 4 codewords with length of 2L and ideal correlation c c c c c c c c c c c c c c c characteristic is as follows: s souuoo n e c e cc
    c
    Figure IMGF000016_0001
    C C
    The code word with longer code length and the same ideal correlation characteristic can be obtained by spreading according to the condition. An eyelid correction method of product complementary code, characterized in that: the correlation property of any product complementary code composed of the C code and the S code needs to satisfy the following condition:
    R(i, j, k) = Re{/½ (i, j,k)-R* s (i, j, k)}
    ∑Sj(l + k)S*(l) , £((-) denotes the second
    Figure IMGF000016_0002
    The 7 th chip of the C code and the S code of the product complementary code denotes a conjugate, Re () denotes a real part, R (i, J, k) denotes a correlation value of the/th codeword and the J 'th codeword delayed by one chip, and when/= J', the autocorrelation characteristic is obtained.
  7. 8. The method of claim 7, wherein one of the conditions is selected
    R0', J, k) and, are unfolded, give: the correlation characteristics of the product complementary code can be controlled by four correlation amounts in the above equation.
  8. 9. An apparatus for checking product complementary codes, comprising: a serial-parallel conversion device, a correlator, an adder and a multiplier;
    the in-phase component and the orthogonal component Q of the product complementary code are input into the serial-parallel conversion device;
    the output of the serial-parallel conversion device is the input of the correlator;
    the output of the correlator is the input of the adder;
    the output of the adder is the input of the multiplier;
    the output of the multiplier is the input of another adder, and the output of the adder is the correlation characteristic quantity R (i, j, k) of the product complementary code.
  9. 10. The apparatus of claim 9 wherein the correlator comprises an integrator.
  10. 11. The apparatus of claim 10, wherein the integrators are an integrator with respect to the real part of the C code, an integrator with respect to the imaginary part of the C code, an integrator with respect to the real part of the S code, and an integrator with respect to the imaginary part of the S code.
    12. The apparatus of claim 11, comprising: the serial-parallel conversion device comprises an integrator related to a real part of the C code, an integrator related to an imaginary part of the C code, an integrator related to a real part of the S code, an integrator related to an imaginary part of the S code, an adder and a multiplier;
    the in-phase component/of the product complementary code is input to the serial-parallel conversion device (1), and the orthogonal component Q of the product complementary code is input to the serial-parallel conversion device (2);
    the output of the serial-parallel conversion device (1) is respectively the input of an integrator (3) related to the real part of the C code, an integrator (4) related to the imaginary part of the C code, an integrator (7) related to the real part of the S code and an integrator (8) related to the imaginary part of the S code;
    the output of the serial-parallel conversion device (2) is the input of an integrator (5) related to the imaginary part of the C code, an integrator (6) related to the real part of the C code, an integrator (9) related to the imaginary part of the S code and an integrator (10) related to the real part of the S code respectively;
    the output of the integrator (3) about the real part of the C code and the integrator (5) about the imaginary part of the C code are the input of the adder (11);
    the output of the integrator (4) about the imaginary part of the C code and the integrator (6) about the real part of the C code are the input of the adder (12);
    the output of the integrator (7) about the real part of the S code and the integrator (9) about the imaginary part of the S code are the input of the adder (13);
    the output of the integrator (8) related to the S virtual code part and the integrator (10) related to the S code real part are the input of the adder (14);
    the outputs of the adder (11) and the adder (13) are the inputs of the multiplier (15); the outputs of the adder (12) and the adder (14) are the inputs of the multiplier (16); the outputs of the multiplier (15) and the multiplier (16) are the inputs of the adder (17);
    the output of the adder (17) is a correlation characteristic quantity R (i, j, k) of the product complementary code.
CNA028181220A 2002-06-21 2002-06-21 Encoding method for product complemenbary code, checking method and checking device Pending CN1555615A (en)

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