WO2007131384A1 - Procédé de codage de plusieurs adresses de temps, espace, fréquence groupées - Google Patents

Procédé de codage de plusieurs adresses de temps, espace, fréquence groupées Download PDF

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Publication number
WO2007131384A1
WO2007131384A1 PCT/CN2006/000947 CN2006000947W WO2007131384A1 WO 2007131384 A1 WO2007131384 A1 WO 2007131384A1 CN 2006000947 W CN2006000947 W CN 2006000947W WO 2007131384 A1 WO2007131384 A1 WO 2007131384A1
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code
codes
basic
group
matrix
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PCT/CN2006/000947
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English (en)
Chinese (zh)
Inventor
Daoben Li
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Daoben Li
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Application filed by Daoben Li filed Critical Daoben Li
Priority to CN200680054569XA priority Critical patent/CN101438524B/zh
Priority to PCT/CN2006/000947 priority patent/WO2007131384A1/fr
Publication of WO2007131384A1 publication Critical patent/WO2007131384A1/fr
Priority to IL195258A priority patent/IL195258A0/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/16—Code allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/16—Code allocation
    • H04J13/18—Allocation of orthogonal codes

Definitions

  • the present invention relates to the field of code division multiple access (CDMA) wireless mobile digital communication, and particularly relates to a multi-address block coding method with high spectral efficiency, high anti-fading capability and high transmission reliability, which is specifically a grouping time, Space, frequency multi-address coding method.
  • CDMA code division multiple access
  • the so-called spectrum efficiency refers to the maximum total transmission rate supported by the system per unit bandwidth in a cell (cel l) or sector (sector) given a system bandwidth.
  • the unit of measurement is bps/Hz/cel l (sector)
  • the so-called transmission reliability refers to the ability of the system to resist fading.
  • wireless channels are typical random time-varying channels, which have random dispers in the time domain, the frequency domain, and the spatial angular domain. These spreads will cause severe fading of the received signal in the corresponding frequency domain, time domain and spatial domain. Fading will seriously deteriorate the transmission reliability and spectral efficiency of the wireless communication system.
  • Diversity can be divided into two categories: apparent divers i ty and hidden divers ty.
  • the explicit diversity technique has no need to elaborate as its name suggests.
  • Hidden diversity technology is a signal design technique. For example, in spread spectrum wireless communication systems and code division multiple access (CDMA) systems, a spread spectrum signal design technique is used, which has a certain resistance against channel time spread. The ability to frequency selective fading.
  • CDMA code division multiple access
  • the essence of diversity is that the transmitted message is "sorted" in the "subchannel" of the uncorrelated or independent fading, and at the receiving end, the output of the "subchannel” is “set”. Unified demodulation of the information they share.
  • the number of uncorrelated or independent fading "subchannels" available referred to as the "order of uncorrelated diversities", the higher the diversity number, the higher the transmission reliability of the system.
  • the maximum irrelevant or independent diversity multiplicity that is, the maximum transmission reliability that the system can achieve is also determined.
  • system bandwidth B Hz
  • symbol duration T M seconds s
  • symbol rate 1/T M symbol rate 1/T M (symbols per second sps)
  • available geospatial range Surrounding R m 2 M 2
  • effective time spread of the channel ⁇ seconds s
  • effective correlation bandwidth of the channel 0- ⁇ Hz
  • Lvl represents the smallest integer of ⁇ because the diversity multiplicity must be an integer.
  • Increasing means increasing the frequency resource B occupied by the system.
  • the increase means increasing the time resource T M occupied by the system. Both of them improve the spectrum efficiency of the system, and only the system space diversity is the exception.
  • any wireless channel especially a mobile wireless channel, is not a time-invariant non-diffusion system. They all have random angular spreads (which produce spatially selective fading); random frequency spreads (which produce temporally selective fading) and random temporal spreads (which produce frequency selective fading). Fading not only seriously degrades system performance, but also greatly reduces system capacity and reduces system spectral efficiency.
  • the time spread of the channel causes adjacent symbols to overlap each other to cause mutual interference, so that inter-symbol interference (ISI) occurs between the front and rear symbols of the user signal of the same address, but different Address user Multiple access interference (MAI) will also occur between the signals. This is because when the relative delay between address signals is not zero, the orthogonality between any orthogonal codes will generally be corrupted.
  • ISI inter-symbol interference
  • MAI Address user Multiple access interference
  • the autocorrelation function of each address code should be an impulse function, that is, the autocorrelation function value should be zero for various relative delays except the origin; in order to make the multiple access interference (MAI) ) is zero, the value of the cross-correlation function between each address code should also be zero for various relative delays.
  • the value of the autocorrelation function origin (the relative delay is zero) is the main peak of the correlation function, and the autocorrelation or cross-correlation function other than the origin is the peak of the autocorrelation or cross-correlation function.
  • the peak of the autocorrelation and cross-correlation of the ideal address code should be zero.
  • both theoretical and ubiquitous searches have shown that there are no multi-address code groups in the real world where the peak is zero.
  • the theoretical Welch bounds point out that the peak of the autocorrelation function and the peak of the cross-correlation function are a pair of contradictions. When one is reduced, the other must increase, and vice versa.
  • the PCT patent application ensures that the address code encoded by it is within a specific window (- ⁇ , ⁇ ), and the autocorrelation function and cross-correlation function of each address code in the complementary sense have no peak.
  • ⁇ is larger than the maximum time spread of the channel (maximum multipath broadening) plus timing error, inter-symbol interference (ISI) and multiple access interference (MAI) do not occur in any two-way synchronous wireless communication system.
  • ISI inter-symbol interference
  • MAI multiple access interference
  • the code length N and the zero window size ⁇ are given, regardless of which coding element is used, including the random element used in the present invention, the maximum number of possible address codes K has been determined, and it is impossible to have more address codes.
  • the number of address codes provided by the inventor is very close to the theoretical world, and basically does not exist. There is room for improvement.
  • the fatal shortcoming of the traditional code division multiple access system is the "far-and-far effect", which is caused by the unsatisfactory cross-correlation properties of the address codes. Because the main peak of a long-distance weak signal is overwhelmed by the peak of a close-range strong signal, it is known that only the main peak is a useful signal. In order to overcome the fatal effect of the "far effect", the traditional CDMA system is strict and fast. The power control technique tries to make the signal of each address user reach the receiver at the same intensity in any case, but it has been proved that the effect of this method is very limited; the theoretically best method is to ensure that each address code is mutually The correlation function has no peaks under the working environment conditions. This is the method adopted by the LAS-CDMA system.
  • Each group of address codes consists of several codes.
  • the autocorrelation and cross-correlation functions of each code in the group are not required to have a "zero correlation window” feature.
  • the present invention can provide more address codes under the same "window" width.
  • the present invention can provide a wider "window", thereby creating conditions for more greatly improving the capacity and spectral efficiency of the system.
  • Another important object of the present invention is to make the encoded address code have a transmission reliability of 4 inches at the same time. That is, it has a very high degree of hidden diversity, and while increasing the number of hidden diversity, the frequency efficiency of the system will not increase but will remain unchanged or remain unchanged.
  • the present invention requires each address user to use a set of codes, although the autocorrelation function and the cross-correlation function between the codes in the group are not ideal, since the codes in the group are used by the same user, the channel fading characteristics are completely consistent.
  • the number of codes in the group is a fixed finite number, which will facilitate the multi-code joint detection and solve the complexity of joint detection in the traditional CDMA system.
  • the length of the code and the number of codes in the basic perfect orthogonal complementary code group are extended;
  • the selection of the substantially perfect orthogonal complementary code dual also includes the following specific steps:
  • the width of the required zero correlation window determines the length of the basic perfect positive interaction complement dual
  • the code length is N.
  • the selection of the substantially perfect orthogonal complementary code dual also includes the following specific steps:
  • the width of the required zero correlation window determines the length N of the basic perfect positive interactive complement dual
  • the code length is N.
  • Perfect orthogonal complementary code dual for X 2' ⁇ 1 0,1,2,
  • the parity bits of the ⁇ code are respectively composed of and ⁇ ; S, the parity bits of the code are respectively composed of ⁇ and ⁇ ; the parity bits of the code are respectively composed of and ⁇ ; the parity bits of the code are composed of (5 2 and ⁇ respectively).
  • a new perfect orthogonal complementary code pair of the desired length ⁇ can be obtained.
  • the selection of the basic time, space, and frequency coding extension matrix further includes the following specific steps: According to the size of the required zero correlation window ⁇ , Determine the number of columns of the extended matrix from the relationship ⁇ 3 ⁇ 4 - 1
  • ⁇ is the length of the perfect perfect orthogonal complement dual, L is the number of columns of the extended matrix, and the unit of ⁇ is calculated by the number of chips;
  • ⁇ , ⁇ is the number of rows of the expansion matrix
  • the basic coding extension matrix is constructed according to the available time, frequency, spatially weakly related random variables (coded elements), the number of rows of the required extension matrix ⁇ and the number of columns L.
  • the basic coding extension matrix constructed only needs to satisfy the following basic conditions:
  • the extended matrix should be a row full rank matrix, that is, each row vector should be linearly independent;
  • the aperiodic and periodic autocorrelation functions of each row vector should have as small a pay peak as possible; the aperiodic and periodic cross-correlation functions between the row vectors should have as small a pay peak as possible.
  • the constructed basic coding extension matrix can be a random matrix, a constant matrix, or even a constant.
  • the number of weakly correlated random elements in each row vector is the hidden diversity of the corresponding wireless communication system.
  • the autocorrelation function of the corresponding code in the window in the group is affected by the autocorrelation function of each row vector Good or bad.
  • the quality of the cross-correlation function in the window between the corresponding codes in the group is determined by the quality of the cross-correlation function between the row vectors.
  • the basic perfect orthogonal complementary code group is generated by the basic perfect orthogonal complementary code dual and the basic time, space, and frequency coding extension matrix.
  • the expanded group address codes have hidden diversity numbers corresponding to the types and numbers of random variables. Meanwhile, the cross-correlation function between different code group address codes has a zero correlation window near the origin, and the window width is perfect. The basic length of the orthogonal complementary code group is determined.
  • Extending the basic perfect orthogonal complementary code group is performed according to the relationship of the spanning tree, which is determined by the generated code group.
  • the transform spanning tree may be a location for exchanging spanning tree C code and S code.
  • the transform spanning tree may be a negation of one of the C code or the S code in the spanning tree, or both.
  • the transform spanning tree may be using a reverse sequence, that is, the C and S codes are taken at the same time as the reverse sequence.
  • the transform spanning tree may be the polarity of the interleaved code bits.
  • the transform spanning tree may be a uniform rotational transform of each code bit in a complex plane.
  • the transform spanning tree may be arranged by synchronizing the C code with each column in the S code in a spanning tree, wherein the columns are in units of codes in the substantially perfect orthogonal complementary code group.
  • the address code is in units of groups, each group has a fixed number of codes, and the mutual function between each group of address codes has a zero correlation window.
  • the address code has a high hidden diversity number, and the effective diversity weight is equal to the number of random variables such as weak correlation time, space and frequency in the coding element and the channel time spread amount in chips in the window. product. ,
  • the address code is in units of groups, and each group has a plurality of codes, and the cross-correlation function of the codes between the groups has a zero correlation window characteristic.
  • the autocorrelation function of each code in the address code group and the cross-correlation function between codes do not require certain ideals, and there is no requirement that a zero correlation window exists.
  • the size of the cross-correlation zero correlation window between each address code group can be adjusted.
  • the adjustment method may be to adjust the length of the pair of substantially orthogonal complementary codes.
  • the adjustment method may be to adjust the number of columns of the basic time, space, and frequency extension matrix.
  • the adjustment method may be to adjust the number of zero elements between the code generation tree coding extension matrix.
  • the number of codes in each address code group can be adjusted by adjusting the number of lines of the basic time, space, and frequency code extension matrix.
  • the autocorrelation function of each code of each address code group is mainly determined by the autocorrelation property of each row of the selected basic time, space and frequency coding extension matrix.
  • the cross correlation function between codes in the group is mainly determined by the selected one.
  • the autocorrelation and cross-correlation properties of each ⁇ horse include the autocorrelation and cross-correlation properties of each address code in the group, which are determined by the duality of the basic orthogonal complementary code and the structure of the corresponding spanning tree.
  • the time, space, and frequency coding extension matrix may be an arbitrary matrix.
  • the time, space, and frequency coding extension matrix includes: time, space, time, frequency, time, space, frequency, and even a constant matrix or constant.
  • the present invention provides a new packet multi-address coding technique that uses time, frequency, space and other related random variables as coding elements.
  • the basic features of this coding technique are as follows:
  • the address code is in units of groups, each group has a fixed number of codes, and the cross-correlation function between each group of address codes has a "zero correlation window" characteristic, and the condition that the window width is the same or wider and the address code length is slightly longer
  • the number of sets of address codes provided by the present invention is the same as the number of codes thereof, but since there are a plurality of codes in the group, the code provided by the present invention The total number has increased substantially, and vice versa. Therefore, the wireless communication system using the present invention as an address code will have higher system capacity and higher spectral efficiency.
  • the encoded address code Since the elements of the address code are weakly related random variables such as time, frequency or space, the encoded address code also has a high hidden diversity number, which can greatly improve the transmission reliability of the system.
  • its _ effective diversity multiplicity is equal to the product of the weak correlation time, space, frequency and other random variables in the coding element and the product of the channel time spread in the "window", for example, the address code element is used.
  • the time spread of the channel has three chip widths.
  • the encoded address code is in "group", each group has several codes, and the cross-correlation function of the code between the groups has a "zero correlation window” feature, if the "window" width is wider than the actual channel time Diffusion plus system timing error, while each user in the system uses a set of codes, the corresponding wireless communication system will not have "far-and-far effect", and the system capacity and spectrum efficiency are greatly improved.
  • the number of codes in each address code group can be adjusted by adjusting the number of lines of the basic time, space and frequency coding extension matrix.
  • the autocorrelation function of each code in each address code group is mainly determined by the autocorrelation property of each row corresponding to the selected basic time, space and frequency coding extension matrix
  • the cross-correlation function between the codes in the group is mainly Determines the cross-correlation properties between the corresponding rows of the selected time, space, and frequency extension matrices. Therefore, it is important to choose an extension matrix with good correlation between each line and autocorrelation and inter-row correlation.
  • each address code (including the group) is determined by the basic orthogonal complementary code dual and the corresponding spanning tree structure.
  • Time, space, and frequency coding extension matrix which can be any matrix, such as time and space; time and frequency; time, space, frequency and even constant matrix. The only difference is the type of diversity and whether it is there.
  • FIG. 1 is a basic code generation tree
  • 'FIG. 2 is a diagram of a specific embodiment of a code generation tree
  • Figure 3a is an original arrangement diagram of column transformations in a spanning tree
  • Figure 3b shows the transformation of the column transformation in the spanning tree.
  • This step can be subdivided as follows:
  • V2-1 1, - ⁇ J—; V2+1, 1, - ⁇ —; , - ⁇ , - ⁇ , etc., here a
  • ⁇ value is not appropriate, then ⁇ may have no solution; sometimes although there is a solution, but it is not convenient for engineering application, at this time, need to re-adjust ( ⁇ value, until we take ( ⁇ and ⁇ The value is satisfactory.
  • Complementary Code pair ( c 1 , / ), solves another pair of shortest basic complement code pairs ( , S 2 ) that are completely orthogonally complementary.
  • ⁇ ( , S, ); ( C 2 , S 2 ) ⁇ is called Perfect Complete Orthogonal Complementary code pairs mate, that is, in a complementary sense, each of them The autocorrelation function and the cross-correlation function between the two pairs are ideal.
  • the underline indicates the reverse sequence, that is, the order of the order is reversed (from the tail to the head);
  • the upper line is a non-sequence, that is, the element values are all inverted (negative) values; * represents a complex conjugate;
  • k is an arbitrary complex constant.
  • Tables 1 through 3 list the autocorrelation and cross-correlation function values in their complementary senses, respectively, and they are all ideal.
  • the code length is N.
  • Method 1 Connect the short codes in the following way
  • Method 4 The parity bits of the code are respectively composed of and ⁇ ; S, the parity of the code is respectively ( ⁇ and
  • parity bits of the ⁇ code are respectively composed of ( ⁇ and ⁇ ; the parity bits of the S 2 code are respectively composed of and ⁇ .
  • Step 2 Selection of basic time, space, frequency code expansion matr ix
  • the basic time, space and frequency coding extension matrix is an important part of extending the "zero correlation window" coding between basic codes into the "zero correlation window” coding between code groups. Since the introduction of the extension matrix is under the same "window" width condition, the available code number provided by the present invention will be greatly improved. On the contrary, the invention can provide a wider "zero correlation” under the same available code number. Window" mouth.
  • the order of the expansion matrix is M x L, where M represents the number of rows of the extended matrix, and L represents the number of columns of the extended matrix.
  • M represents the number of rows of the extended matrix
  • L represents the number of columns of the extended matrix.
  • the number of rows of the extension matrix M is equal to the number of codes in each code group. The larger the M, the higher the spectral efficiency of the system, but the higher the system complexity.
  • the number of columns L of the expansion matrix is related to the width of the "zero correlation window" of the cross-correlation function between the formed address code group and the group.
  • L is generally greater than or equal to the multiplicity of the system's implicit diversity, that is, the number of random variables such as time, space, and frequency that are actually associated with weak fading. These random variables are elements in the extended matrix. In traditional system design, people Unrelated diversity is often required, which will result in the requirement that the coding elements should have irrelevant or independent fading.
  • Step 2 can be subdivided as follows:
  • a ⁇ NL - determines the number of columns L of the extended matrix.
  • N is the length of the perfect perfect orthogonal complementary code pair
  • L is the number of columns of the expansion matrix; the unit of ⁇ is calculated in chips.
  • the extension matrix should be a row full rank matrix, ie each row vector should be linearly independent;
  • the aperiodic and periodic autocorrelation function of each row vector should have a peak that is as small as possible.
  • the absolute value is not greater than e- 1 or even 0.5.
  • the aperiodic and periodic cross-correlation functions between the vector lines should have as many "small” peaks as possible.
  • the absolute value is not greater than or even 0.5.
  • the basic coding extension matrix is «1. This is an orthogonal matrix, where two spatial or polarization or frequency diversity random variables, or even two constants, have no requirement for their correlation. When their correlation is 1 (ie, a constant matrix), the implicit diversity gain disappears, but it is still beneficial for improving system capacity and spectral efficiency.
  • the matrix has two upper and lower sub-blocks, wherein ⁇ , , 2 in the upper sub-block are two spatial or polarization diversity random variables but the carrier frequency is y; and 01 and 2 in the lower sub-block are also two spatial or polarization diversity random variables. , just change the carrier frequency to / 2 .
  • ⁇ , , 2 in the upper sub-block are two spatial or polarization diversity random variables but the carrier frequency is y; and 01 and 2 in the lower sub-block are also two spatial or polarization diversity random variables. , just change the carrier frequency to / 2 .
  • ⁇ is "a carrier of related fading.
  • the address code group formed by the multi-carrier coding extension matrix described above has the capability of at most two hidden spaces or polarization diversity, and multiple carriers are used to increase the capacity and spectral efficiency of the system.
  • Basic extension matrix two is
  • the matrix has two sub-blocks above and below, where / 2 is a two-frequency diversity random variable in the upper sub-block but uses an antenna, and /, / 2 in the lower sub-block are also two frequency diversity random variables, just using an antenna. 2 .
  • / 2 is a two-frequency diversity random variable in the upper sub-block but uses an antenna
  • /, / 2 in the lower sub-block are also two frequency diversity random variables, just using an antenna. 2 .
  • This coding matrix can also be generalized to multiple antennas, ie
  • the address code group formed by the above multi-antenna coding extension matrix two has the capability of at most two hidden frequency diversity, and multiple antennas are used to increase the capacity and spectral efficiency of the system.
  • the above two coding extension matrices can also be used in combination.
  • ⁇ , ⁇ , ⁇ can be any spatial, frequency, polarization diversity random variable or a new diversity random variable generated by their combination, or any constant.
  • the "zero correlation window" multi-address coding method of Li Daoben in PCT/CN00/0028 is only a special case when the extension matrix is 1 X 1 matrix (constant) in the present invention.
  • composition of Basic perfect complementary orthogonal code pair group mate The composition of Basic perfect complementary orthogonal code pair group mate.
  • the basic perfect orthogonal complementary code group is generated by the basic perfect complementary orthogonal code pair mate and the basic time, space and frequency coding extension matrix.
  • the generation method is as follows:
  • the basic perfect orthogonal complementary code group has two sets of codes, each group has M pairs of codes, and the code length is NL + Ll.
  • the cross-correlation function between each code pair in any group and any code pair in another group is ideal in a complementary sense, that is, there is no peak at all, and each code pair in the group is autocorrelation or cross-correlation. Functions are not guaranteed to have ideal characteristics.
  • ® means Kronecker product
  • 0 means Mx (L-l) zero matrix.
  • Mx ( NL + L- ⁇ ) order matrices where the 0 matrix is used to isolate the two generating units in the spanning tree, in the worst case possible "caused, and the maximum protection is set. The interval can be shortened or even cancelled according to the actual situation.
  • the 0 matrix can also be placed at the end of each code group and placed at the head.
  • the basic coding extension matrix A is:
  • the length and number of codes of the basic perfect orthogonal complementary code group are expanded.
  • the extended group address codes if the elements of the basic coding extension matrix are composed of "weak" correlation diversity random variables, it will have an implicit diversity multiplicity corresponding to the type and number of random variables, and different code group addresses.
  • the cross-correlation function between codes has a "zero correlation window" near the origin, and its “window” port width is determined by the basic length of the perfect orthogonal complementary code pair.
  • the initial 0 stage we have only one perfect orthogonal complementary code pair, and there are two sets of codes.
  • the code length is 2 ⁇ 2 times of the initial stage.
  • the cross-correlation function in the even is ideal, but even and even There is a "zero correlation window" between the cross-correlation functions.
  • each code group is a perfect orthogonal complementary code pair, and the cross-correlation function of each code is ideal, but there is a "zero correlation window" in the cross-correlation function of each code.
  • the width of the unilateral "window” port is not less than the basic code length of the two even “roots". For example, in Figure 1, the unilateral "window" of the cross-correlation function between codes in 1 2 and 11 2 The width is not narrower than the basic length of the ⁇ medium code minus one, because it is the common "root" of 1 2 and 11 2 .
  • the unilateral "window" mouth width of the cross-correlation function between codes in III 2 and IV 2 is not narrower than the basic length of the 11-coded code minus 1, because 11, is the common "root” of 111 2 and IV 2 .
  • ⁇ 2 or 12 and in IV 2-sided among the cross-correlation function code "window” opening width can not be less than I. That is, the basic code length of the initial root is decremented by one, because the initial roots are their common "roots".
  • the so-called “basic code length” It refers to the length of the code that is not included in the last 0 element, and the 0 element in the middle part should be calculated within the basic code length.
  • the basic coding extension matrix used in the present invention may be a random matrix. It is only possible for users of different addresses to use the same extension matrix at the base station, but for address users at different mobile stations, when the basic coding matrix is a random matrix, it is no longer possible to use the same coding extension matrix. In the case where the extension matrix is not the same matrix, can it still guarantee the "zero correlation window" characteristic of the cross-correlation function between the code groups? The answer is yes.
  • different "rows”, ie, code extension matrices in different code groups may be the same matrix (for example, applied in a base station), or may be a homogeneous matrix (for example, on a mobile basis). In the station application, but in any case must guarantee the same "row", that is, the code extension matrix in the same group is the same matrix.
  • Figure 2 is an example of a specific code spanning tree. Only two phase trees are drawn for simplicity.
  • the basic orthogonal complementary code pair used in the figure is
  • two even (c ⁇ S, ), (c 2 , s 2 ) and ( , S3 ), ( c 4 , s 4 ) are generated, as described above, ( ⁇ S, ), ( C 2 , S 2 ) and ( C;, ), ( c 4 , s 4 ) should be perfectly orthogonal complementary code pairs, that is, cross-correlation functions of codes between different code groups in each even Should be ideal, but the cross-correlation function between different even codes should have a "zero correlation window" feature.
  • Table 11 Relative shift of the autocorrelation and cross-correlation function of the (C 2 , S 2 ) code group in the first stage of Figure 2 ⁇ -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 From 0 0 0 0 0 0 8 8bA 8 ⁇ b 2 0 0 0 0 0 0 0 0 0 0 Phase i? 22 ( ) 0 0 0 0 0 0 0 0 0 — 8 ⁇ [6 2 0 0 0 0 0 0 0 0 off
  • Table 12 Relative shift of the autocorrelation and cross-correlation function of the ( , ) code group in the first stage of Figure 2 ⁇ -9 -8 -6 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9
  • Table 14 Cross-correlation function of codes between different code groups in the first stage of Figure 2.
  • the basic perfect complement code set in the initial "root" in the spanning tree completely determines the nature of the sets of address codes that are extended by the spanning tree.
  • the address code itself has a hidden diversity multiplicity equal to the number of weakly correlated random variables in the corresponding row of the coding extension matrix, and the maximum value is the number of columns L of the coding extension matrix.
  • the actual coefficient has the largest hidden diversity multiplicity equal to the product of L and the amount of time spread of the actual channel in chips.
  • Figure 1 shows only one of the most basic spanning trees. There are many types of spanning trees, but they are mathematically equivalent. Transforming the spanning tree can produce a large number of address code group variants. These transformations bring a lot of convenience to the engineering, because there are often many new and even wonderful properties between the code groups generated before and after the transformation, which can be adapted. Different engineering needs, such as networking needs, switching needs and even the need to expand capacity. Some of the main changes are listed below:
  • a C code is ⁇ ⁇ Q ⁇ , If each position is rotated by 72 degrees, that is, the rotation of one hook is turned into a bit rotation of 144 degrees, that is, even rotation C ( +21ff) ; If fi is rotated 216 degrees, that is, the rotation for three weeks is changed to C, e C 2 e J1 ⁇ 22+2, ff) , ; If each bit rotates 288 degrees, the change around the hook is C 2 e M ⁇ C ( +2 ' ff ), C, e M ⁇ C ( +72 °). Among them.
  • the C code and the corresponding S code are rotated in the same way.
  • the correlation function "zero window, the position and the position of the peak will not change, but the polarity and magnitude of the relevant peak are related to the rotation angle.
  • the permutation transformation may have P !
  • the wireless communication system using the present invention must ensure that the C code can only be operated with the C code (including itself and others), and the S code must be associated with the S code (including itself and others).
  • C code and S code are generally not allowed to meet. Therefore, special isolation measures should be adopted in engineering. For example, under certain propagation conditions, if two propagating polarized electromagnetic waves have synchronous fading, C and S codes can be used. Modulated separately on two mutually orthogonal polarized waves (horizontal and vertical polarized waves, left-handed and right-handed polarized waves); as another example, when the channel is fading over two or more codes for a long time When it is unchanged, the C and S codes can be placed in two time slots that do not overlap after transmission, and so on.
  • correlation diversity means that the fading between "subchannels” is related, that is, allowing partial overlap between "subchannels”, so that when given channel "space” and system parameters, the possible diversity "heavy” The number will increase.
  • the performance of correlation diversity is inferior to uncorrelated diversity under the same diversity "heavy” number, but both theory and experiment have proved that as long as the correlation coefficient is not large, such as less than e-'s 0.37 Even 0.5.
  • the present invention provides a multiple address coding technique in Code Division Multiple Access (CDMA) and other wireless communication systems. Unlike traditional address coding techniques, where each address code element (chip) is a fixed binary value (+ or -), a multivariate value, or a complex value.
  • the address code elements (chips) used in the present invention are not necessarily fixed values but may be random variables or, more specifically, fading variables that produce random fluctuations after transmission over different "subchannels". Since fading exists only in three types of time, frequency and space, the address coding of the present invention is also referred to as time, space and frequency address coding.
  • the effect of the present invention is that there is a "zero correlation window" between the groups and groups of the encoded address codes, and each group of address codes is composed of several codes, and the autocorrelation and cross-correlation functions of the codes in the group are not It is required to have a "zero correlation window" characteristic.
  • the present invention can provide more address codes under the same conditions of "window, width”. Conversely, under the same number of address codes, the present invention can provide a wider "window", thereby creating conditions for a greater increase in system capacity and spectral efficiency.
  • the invention makes the encoded address code have high transmission reliability at the same time, that is, has a high hidden diversity multiplicity, and while increasing the hidden diversity multiplicity, the spectral efficiency of the system is not lowered but is increased or maintained. change. Since the present invention requires each address user to use a set of codes, although the autocorrelation function and the cross-correlation function between the codes in the group are not ideal, since the codes in the group are used by the same user, the channel fading characteristics are completely consistent. At the same time, the number of codes in the group is a fixed finite number, which will facilitate the multi-code joint detection and solve the complexity of joint detection in the traditional CDMA system.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Error Detection And Correction (AREA)
  • Radio Transmission System (AREA)

Abstract

La présente invention concerne un procédé de codage de plusieurs adresses de temps, espace, fréquence groupées qui permet d'utiliser des variables ou des constantes aléatoires à faible corrélation telles que le temps, l'espace ou la fréquence et autres en tant qu'éléments de codage. Ce procédé comprend les étapes suivantes pour effectuer le codage: la sélection de paires de codes orthogonaux complémentaires parfaits basiques; la sélection d'une matrice d'expansion de codes basiques de temps, d'espace et de fréquence; la construction d'un groupe de paires de codes orthogonaux complémentaires; l'étalement de la longueur des codes et du nombre de codes dans le groupe de paires de codes orthogonaux complémentaires parfaits basiques conformément au procédé d'arbre maximal; la transformation de l'arbre maximal. Cette invention permet aux systèmes de communication CDMA ou aux autres systèmes de communication utilisant ces codes d'adresse d'avoir une meilleure efficacité du spectre de fréquences et une plus grande capacité tout en présentant une meilleure aptitude anti-évanouissement c'est-à-dire une meilleure multiplicité en diversité implicite et une fiabilité de transmission supérieure, un seuil SNR de réception plus faible, de sorte qu'il est nécessaire d'avoir une puissance de transmission plus faible pour assurer une fiabilité supérieure et un débit de transmission plus élevé des besoins réels du projet.
PCT/CN2006/000947 2006-05-12 2006-05-12 Procédé de codage de plusieurs adresses de temps, espace, fréquence groupées WO2007131384A1 (fr)

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CN200680054569XA CN101438524B (zh) 2006-05-12 2006-05-12 一种分组时间、空间、频率多地址编码方法
PCT/CN2006/000947 WO2007131384A1 (fr) 2006-05-12 2006-05-12 Procédé de codage de plusieurs adresses de temps, espace, fréquence groupées
IL195258A IL195258A0 (en) 2006-05-12 2008-11-12 A grouping time, space, frequency multiaddress coding method

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