WO2004068760A1 - Procede pour coder et appliquer des codes d'acces multiples a etalement du spectre avec des fenetres de correlation intergroupe nulle - Google Patents

Procede pour coder et appliquer des codes d'acces multiples a etalement du spectre avec des fenetres de correlation intergroupe nulle Download PDF

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WO2004068760A1
WO2004068760A1 PCT/CN2003/000115 CN0300115W WO2004068760A1 WO 2004068760 A1 WO2004068760 A1 WO 2004068760A1 CN 0300115 W CN0300115 W CN 0300115W WO 2004068760 A1 WO2004068760 A1 WO 2004068760A1
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code
zero
correlation window
orthogonal complementary
zero correlation
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PCT/CN2003/000115
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WO2004068760A8 (fr
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Yongzhong Zou
Daoben Li
Yongsheng Zhang
Li Fang
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Linkair Communications, Inc.
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Priority to AU2003303842A priority Critical patent/AU2003303842A1/en
Priority to CN03805482.5A priority patent/CN1640040A/zh
Priority to PCT/CN2003/000115 priority patent/WO2004068760A1/fr
Publication of WO2004068760A1 publication Critical patent/WO2004068760A1/fr
Publication of WO2004068760A8 publication Critical patent/WO2004068760A8/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/10—Code generation
    • H04J13/14—Generation of codes with a zero correlation zone
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/004—Orthogonal

Definitions

  • the present invention relates to the technical field of spread spectrum and code division multiple access (CDMA) wireless communications, and in particular, to a high-frequency and universal spread-spectrum multiple access coding with zero correlation window in a personal communication system (PCS). Specifically, it is a spread-spectrum multiple access code with a zero correlation window between groups and its symptomatic method.
  • CDMA code division multiple access
  • PCS personal communication system
  • spectrum efficiency refers to the maximum number of users that can be accommodated by a system in a cell (cel l) or sector (sector) when given the user's transmission rate and system bandwidth. Its measurement unit is per cell (or sector). The total transmission rate supported by the system per unit bandwidth. Obviously, the higher the frequency efficiency, the larger the system capacity.
  • FDMA frequency division multiple access
  • TDMA time division multiple access
  • CDMA Code division multiple access
  • FDMA frequency division multiple access
  • TDMA time division multiple access
  • the capacity of a code division multiple access (CDMA) system depends on the level of interference in the system. Therefore, whether or not the interference level in the system can be controlled will become the key to the success or failure of a code division multiple access system.
  • Interference can be divided into four major parts: First, the local and internal noise levels, there is no other method except for using low-noise amplifiers; Second, inter-symbol also known as inter-symbol interference (ISI); Third, multiple-access interference ( MAI), that is, interference from other users in the cell; the fourth is adjacent cell or inter-channel interference (ACI). for ISI, MAI. ACI can be reduced or even eliminated by selecting an address code with good performance.
  • ISI inter-symbol interference
  • ACI inter-channel interference
  • each user has its own unique address code for mutual identification.
  • the spreading address codes of each user should also be orthogonal to each other. The requirement of this orthogonality is consistent for any multiple-access system. If the channel is an ideal linear time-frequency non-proliferation system, and there is a strict synchronization relationship within the system, then the orthogonality between user address codes can be ensured. But none of the actual channels is ideal, and strict synchronization is impossible for signals in time and frequency spread channels. Therefore, it is the life of a code division multiple access (CDMA) system to maintain the orthogonality between address codes in a non-ideal time-frequency diffusion channel.
  • CDMA code division multiple access
  • mobile communication channels are typical random time-varying channels.
  • the former will cause time-selective fading of the received signal, that is, the level of the received signal will have different random fluctuations over time; the latter will cause frequency-selective fading of the received signal, that is, different spectral components of the received signal will have different random fluctuations. Variety.
  • fading will also significantly reduce system capacity.
  • the time spread of the channel caused by multipath propagation prevents the signals from reaching the receiving point at the same time, so that the signals between adjacent symbols of the same user overlap with each other, resulting in inter-symbol interference (ISI).
  • ISI inter-symbol interference
  • the time spread of the channel will also worsen multiple access interference. This is because when the relative delay between different user signals is zero, its orthogonality is easily guaranteed, and any orthogonal code can be used. But when the relative delay between signals is not zero, it will become very difficult to maintain their orthogonality.
  • the signal waveform selected by each user that is, the autocorrelation function of its address code should be an ideal impulse function, that is, it should be zero except for the origin.
  • the signal waveform selected by each user that is, the cross-correlation function between the address codes should be zero at various relative delays. From the perspective of orthogonality, apart from the relative zero delay, each spreading address code should be orthogonal to any non-zero relative delay, and any relative delay (including (Zero delay) should be orthogonal to each other.
  • the value of the autocorrelation function at the origin is referred to as the main peak of the correlation function, and the value of the autocorrelation or cross-correlation function outside the origin is referred to as the peak of the correlation function.
  • the peaks of the auto-correlation and cross-correlation functions between ideal multiple access codes should all be zero.
  • the Welch bound of the theory states that there are no multiple access code groups with zeros everywhere in the binary, finite, and even complex domains.
  • the peaks of the auto-correlation function and the peaks of the cross-correlation function are a contradiction. When one is required to decrease, the other is necessarily increased.
  • NASA also announced that it has exhaustively calculated various codes and proved that the Welch world cannot be broken.
  • NASA calculates only the group codes exhaustively, and the Welch bound is only valid for the sub-plural domains. Outside of this, ideal address codes are possible.
  • UCLA Los Angeles
  • UCLA Los Angeles
  • NOKIA TELECOMMUNICATIONS applied their ideas to the time division / code division (TDMA / CDMA) mixed system and applied The European patent, whose patent publication number is EP 0600713A2, and the application number is 93309556. 4.
  • This encoding method is actually encoding in a high-dimensional space.
  • the high-dimensional space has broken through the conditions for the establishment of the Welch world. But this encoding method The spectrum efficiency is extremely low and has no practical value. This is the reason why it was proposed that no one has used it for nearly thirty years.
  • this coding method needs to use N 2 basic codes and each at least for an N-bit code, i.e. total of N 3-bit addresses supported e.g. N: If N is the number of addresses 128, a 16QAM modulation scheme, the It should frequency of the system only 441 ⁇ 1 ( ⁇ 3 ⁇ 4 ⁇ ; 3 / ⁇ (bits / hertz).
  • the complementary code group is ⁇ C S l M
  • the code length of the C or S part is N
  • the width of the one-sided zero correlation window is: ⁇
  • the zero correlation window bound M ⁇ ⁇ ⁇ ⁇ So given the code length and zero window size
  • one method is to send a non-zero window code at the transmitting end, and use joint detection technology at the receiving end to achieve the maximum Excellent reception.
  • the complexity of this detection method is as the number of users M
  • some sub-optimal joint detection algorithms are used, such as decorrelated multi-user detection, interference cancellation techniques, etc., but these algorithms will bring performance loss, and when the number of users is large The complexity is still significant.
  • the purpose of the present invention is to provide a spread spectrum multiple access code encoding and application method with zero correlation windows between groups, so that the correlation characteristics between the formed spread spectrum multiple address codes and the groups have a "zero correlation window, That is, the cross-correlation function between the groups of address codes in the zero correlation window does not have peaks, thereby eliminating multiple access interference (MAI) between groups, and although there is multiple access interference between each address code in the same group ( MAI), but in specific applications, joint detection technology can be used to achieve optimal reception.
  • the new spreading code coding method with inter-group zero correlation window code proposed by the present invention uses both the characteristics of zero correlation window and The use of technologies such as joint detection, interference cancellation technology, equalization technology, etc., provides the possibility for increasing the system capacity.
  • the present invention solves the complexity problem of applying joint detection in a traditional CDMA system, which can greatly increase the complexity. The reduction.
  • the above-mentioned spread-spectrum multi-address codes with "zero correlation windows" between groups have the following four characteristics: (1) A cross-correlation function between the spread-spectrum address codes of each group has a zero-correlation window near the origin.
  • the relative delay between each group of spreading address codes is completely orthogonal when the relative delay is less than the width of the zero correlation window;
  • the autocorrelation function of each spreading address code is between the above groups Except for the origin, the zero correlation window is not zero only at two non-zero relative delays, and is zero at other places, that is, it has ideal characteristics;
  • a method for encoding a spread spectrum multiple access code with a zero correlation window between groups is characterized by including the following steps: Generate a pair of basic orthogonal complementary code groups;
  • the generating a pair of basic orthogonal complementary code groups refers to: selecting a pair of basic orthogonal complementary code group pairs (C S ' x ), (C, 2 ) where each code length is N and the zero correlation window width is L. S, 2 );
  • C (C n C 12 ... C 1N ), S '(S u S 12 ... S 1N ), S 22 ... S 2N );
  • Group refers to complement core: substantially complementary orthogonal codes of the group of (C, S), (C '2, s, 2) expanded into complementary orthogonal code groups having a core group of zero correlation window:
  • the expansion of the orthogonal complementary code group cores with zero correlation windows between groups refers to: according to the actual maximum number of user addresses required, the orthogonal complementary code group cores are coded in the spanning tree structure. And the expansion of the number of codes, there is a zero correlation window near the origin of the cross-correlation function between each set of spreading address codes, and the width of the window is greater than or equal to 2L-1; according to the orthogonality, it can be obtained that:
  • the spreading address codes are completely orthogonal when the relative delay is smaller than the width of the zero correlation window; the autocorrelation function of each spreading address code after the expansion is in the zero correlation window between the groups except the origin, Only at two non-zero relative delays are not zero, and zero everywhere else; within the same group
  • the cross-correlation function of each spread-spectrum address code is not zero only at two non-zero relative delays within the above-mentioned inter-group zero correlation window, and is zero elsewhere.
  • a zero guard interval or time slot can be inserted into the orthogonal complementary code group core of the inter-group zero correlation window or the extended spreading address codes, so as to increase the interval between the spreading address codes formed by the groups.
  • the present invention also provides a method for applying a spread spectrum multiple access code with a zero correlation window between groups, which is characterized by including the following steps:
  • the generating or selecting a pair of basic orthogonal complementary code groups refers to: generating or selecting one or more groups of basic orthogonal complementary code group pairs.
  • the non-periodic autocorrelation and cross-correlation functions of the C code and the s code are oppositely formed in the zero correlation window except the origin, and the value of the autocorrelation function and the cross-correlation function after addition are zero except for the origin.
  • the pair of basic orthogonal complementary code groups (c, s), (c, 2 , s, 2 ) refer to: their auto-correlation and cross-correlation functions are aperiodic auto-correlation and cross-correlation functions between C codes and Aperiodic between S codes Sum of auto-correlation and cross-correlation functions, where within a zero correlation window of width L, the aperiodic auto-correlation and cross-correlation functions of C code and S code are opposite to each other except the origin, and the value of the added autocorrelation function and cross-correlation The value of the function is zero except for the origin; a method for generating the basic orthogonal complementary code pair (C 15 Si), (C 2 , S 2 ) can be used by Professor Li Daoben in PCT / CN00 / 00028 Generating method of basic orthogonal complementary code pair.
  • the length of each code of the extended orthogonal complementary code group kernel is 2N, and the width of the zero correlation window between groups is greater than or equal to 2L-1.
  • the insertion of a zero guard interval or time slot into the core of an orthogonal complementary code group with zero correlation windows between groups refers to: First, a basic orthogonal complementary code group with a length N of each code and a width L of a zero correlation window window.
  • every L + 1 chips T zeros are inserted, and a new orthogonal complementary code group kernel formed therefrom has a width of zero correlation window greater than or equal to 2L-1, and thus the new orthogonal complementary code group kernel continues to expand according to a tree structure, and the obtained The width of the zero correlation window between the orthogonal complementary code group pairs is greater than or equal to 2L-1;
  • each code of the basic orthogonal complementary code group pair (CS t X (C 2 , S 2 ) is N and the width of the zero correlation window is L
  • the length of each code after the expansion is 2N positive T zeros are inserted for every L + 1 chips (Chip) of the cross complementary code group core, and are inserted according to the following zero guard interval or time slot insertion mode, that is, each L + 1 chip (Chip) is inserted at the tail T zeros, and the width of the zero correlation window between the new orthogonal complementary code group cores formed thereby is greater than or equal to 2L-1, and thus the new orthogonal complementary code group cores are continuously expanded according to the spanning tree structure.
  • the inter-group zero correlation window width of the orthogonal complementary code group pair is greater than or equal to 2L-1; after inserting the T zeros, the inter-group zero correlation window width of the new orthogonal complementary code group kernel formed thereby is maximized.
  • the manner of inserting the T zeros includes: T zeros are inserted at the tail of each L + 1 chip (chip), or T zeros are inserted at the head of each L + 1 chip (chip), and the like.
  • the maximum number of user addresses required determine the maximum number of user addresses required, and use the selected orthogonal complementary code group kernel with zero correlation window between groups as the origin of the spanning tree structure, and perform code length and number of codes in the spanning tree structure.
  • the cross-correlation function between the spreading address codes of each group after expansion has a zero correlation window between the groups near the origin; the expansion will be based on the maximum number of users required and the number of pairs of selected basic orthogonal complementary code pairs Determine the number of expansion stages required in the spanning tree structure.
  • the width of the inter-group zero correlation window of the orthogonal complementary code group obtained in the third step is 2L-1, then we can insert T zeros for every L + 1 chips (Chip), thus forming a new positive
  • the width of the zero correlation window between the complementary code groups is greater than or equal to 2L-1.
  • the criterion for inserting the T zeros is to maximize the width of the zero correlation window between the new orthogonal complementary code groups thus formed.
  • There are many methods for inserting the T zeros for example, every L + 1 codes The tail of the chip is inserted at the head of each L + 1 chip, and will not be listed here.
  • Equivalent transformation can be performed on the generated multi-address code.
  • the equivalent transformation includes: exchanging positions of C and S codes, exchanging positions of C1 and C2 and S1 and S2 at the same time, inverting code sequence, inverting each code position, and the like.
  • the spreading address code formed above must be used to ensure that C code operates only with C code (including itself and other codes), and S code operates with S code (including itself and other codes).
  • Two orthogonal transmission channels with synchronous fading can be used to transmit the above-mentioned c code and S code, respectively, and carry the same information bits during modulation, and despread and decompress them to the output port.
  • the C code and the S code can be respectively modulated on mutually orthogonal polarized waves, or the C code and the S code are placed on each other and are not mutually separated after transmission. Overlapping two time slots.
  • the expansion of the code length and code number of the orthogonal complementary code group core in a tree structure refers to: if (d, S,), (C 2 , S z ) are a pair of code lengths of N.
  • Orthogonal complementary code group kernels with a width L of zero correlation window window can generate two pairs, that is, four orthogonal complementary code group pairs each having a code length of 2N in the following manner:
  • the description of the extended spreading address codes with inter-group zero correlation windows by inserting zero guard intervals or time slots refers to: for each of the groups with inter-group zero correlation windows generated by the orthogonal complementary code group core extension
  • the spreading address code is inserted into a certain number of zero guard intervals or time slots, and the new orthogonal complementary code group formed by the group has a width of the zero correlation window larger than that of the original orthogonal complementary code group. .
  • the beneficial effect of the present invention is that by providing a spread spectrum multiple access code encoding and application method with zero correlation windows between groups, the correlation characteristics between the formed spread spectrum multiple address codes and the groups have a "zero correlation window" ", That is, the correlation function and the cross-correlation function between the address codes of each group in the zero correlation window have no peaks, thereby eliminating multiple access interference (MAI) between groups, and although each address code in the same group exists, Multiple access interference (MAI), but in specific applications, joint detection technology can be used to achieve optimal reception.
  • MAI multiple access interference
  • MAI Multiple access interference
  • the new inter-group zero-correlation window code spreading code encoding method proposed by the present invention not only uses the characteristics of the zero-correlation window, but also uses technologies such as joint detection, interference cancellation technology, and equalization technology, which is to increase the system. Capacity offers the possibility.
  • the present invention solves the complexity problem of applying joint detection in the traditional CDMA system, which can greatly reduce the complexity.
  • the above-mentioned spread-spectrum multi-address codes with "zero correlation windows" between groups have the following four characteristics: (1) A cross-correlation function between the spread-spectrum address codes of each group has a zero-correlation window near the origin. From the perspective of orthogonality, the relative delay between the spreading address codes is completely orthogonal when the relative delay is less than the width of the zero correlation window; (2) The autocorrelation function of each spreading address code is zero between the groups described above.
  • FIG. 1 is a first schematic diagram of a spanning complementary code group spanning tree having a zero correlation window between groups according to the present invention.
  • FIG. 2 is a second schematic diagram of a spanning complementary code group spanning tree with a zero correlation window between groups according to the present invention.
  • FIG. 3 is a schematic diagram of a method for generating a basic orthogonal complementary code group pair according to the present invention.
  • the first step is to generate or select a pair of basic orthogonal complementary code groups.
  • the pair of basic orthogonal complementary code groups (C 1 S, (C 2 , S 2 ) with each code length N and the width of the zero correlation window window L refers to: its autocorrelation and crosscorrelation
  • the functions are the sum of the non-periodic autocorrelation and cross-correlation functions between the C code and the S-code, and the non-periodic autocorrelation and cross-correlation function between the S code.
  • the autocorrelation and cross-correlation functions are opposite to each other except the origin, and the value of the added autocorrelation function and the cross-correlation function are zero except for the origin.
  • the pair of basic orthogonal complementary code groups (Ci, Si), (C 2 , S 2 ) —A method for generating a pair of basic orthogonal complementary code pairs in which each code length in PCT / CNOO / 00028 by Professor Li Daoben is N zero correlation window width is 2N-1.
  • the pair of basic orthogonal complementary code groups can be extended as follows in code length and zero correlation window width:
  • the width of the zero correlation window is greater than or equal to L.
  • Table 1 shows the values of the autocorrelation and cross-correlation functions of the C1 and C2 code pairs with different mutual shifts.
  • the number of address codes is 2, and the length of each code is 1.
  • the basic orthogonal complementary code group pair has only one of the above basic forms, and other forms such as exchange (C 2 , and Si, S 2 positions, and exchange C, S code positions Sequence inversion or interleaving polarity and rotation are equivalent to the above basic forms, and there is no substantial difference between them. It should be noted that for orthogonal complementary codes, when performing correlation or matching filtering operations on them, the C code It only operates with C code, S code, and S code only. C code and S code do not meet each other during operation.
  • a longer pair of basic orthogonal complementary code groups can be generated as follows:
  • the S code is formed by concatenating the original 3 1 and S 2 codes, and is expressed as:
  • Table 4 shows the correlation function of the new basic orthogonal complementary code pair. It can be seen that its complementary autocorrelation function and cross-correlation function are all ideal. Another method is to reverse the order of the codes, that is,
  • FIG. 3 is a spanning tree diagram of a basic complementary code group pair.
  • the pair of basic orthogonal complementary code groups shown in Figure 3 will be used.
  • a pair of code groups within ⁇ > are basically orthogonal complementary code group pairs, and their complementary autocorrelation functions and cross-correlation functions
  • ⁇ in FIG. 3 is only a basic complementary code group pair, and there are many equivalent forms, for example, exchanging the order of them up and down, or left and right, reversing the order of them before and after, reversing the separation, In-plane rotation, etc. Both can get equivalent basic complementary code group pairs.
  • Their autocorrelation function and cross-correlation function are all ideal.
  • the second step is to generate an orthogonal complementary code group kernel with a zero correlation window between groups.
  • the length of each code of the extended orthogonal complementary code group kernel is 2N, and the width of the zero correlation window between the groups is greater than or equal to 2L-1.
  • Each L + 1 chips (Chip) T zeros are inserted at the tail, and the new orthogonal complementary code group kernel has a width of zero correlation window width greater than or equal to 2L-1, and the new orthogonal complementary code group kernel follows the tree shape of the third step.
  • the structure continues to expand, and the width of the zero correlation window between the orthogonal complementary code group pairs obtained is greater than or equal to 2L-1.
  • the criterion for inserting these T zeros is to make the new orthogonal complementary code group core group formed thereby.
  • the width of the zero correlation window is maximized.
  • a method of inserting the T zeros is, for example, inserted at the tail of each L + 1 chip (Chip), and inserted at the end of each L + 1 chip (Chip). The head is not listed in jtb-enumeration.
  • a pair of orthogonal complementary code groups can obtain two pairs or two groups of four new orthogonal complementary codes, but the length of each code is doubled. From these two pairs or two groups of four new orthogonal complementary codes, A total of eight new orthogonal complementary code groups of four ten or four groups can be derived, and then eighteen or eight groups of sixteen orthogonal code groups can be derived.
  • Complementary codes ... where there is a zero correlation window for the cross-correlation function of code groups between pairs. This process can be described by a spanning tree graph relationship. Fig. 1 is one kind of this kind of spanning tree graph, and Fig. 2 is another kind of spanning tree. There are many other types of spanning trees, and the relationships between them are equivalent transformations. The equivalent transformation does not change the width of the zero correlation window between groups, but sometimes it can change the height and distribution of the peaks outside the zero correlation window.
  • the width is greater than or equal to II 5; the autocorrelation function of each spreading address code after expansion is between the above groups
  • the zero correlation window is zero except for the origin and the relative shift ⁇ is 1 and ⁇ 1; the cross-correlation function of two spread-spectrum address codes in the same group is only two in the above-mentioned inter-group zero correlation window. Relative shifts ⁇ are 1 and -1 are not zero at +
  • the fourth step is to insert a certain number of zero guard intervals or time slots for each spread-spectrum address code that has an inter-group zero correlation window after expansion, thereby forming a new orthogonal complementary code group with zero correlation between groups.
  • the window width is greater than or equal to the inter-group zero correlation window width of the original orthogonal complementary code group.
  • the inter-group zero correlation window width of the orthogonal complementary code group obtained in the third step is 2L-1
  • the inter-group zero correlation window width of the cross complementary code group is greater than or equal to 2L-1.
  • the criterion for inserting the T zeros is to maximize the width of the zero correlation window between the new orthogonal complementary code groups thus formed. There are many methods for inserting the T zeros, for example, every L + 1 The tail of the chip is inserted at the head of every L + 1 chip. It will not be listed here.
  • the width of the zero-correlation window between the four groups with each code length being 8 orthogonal complementary code groups is 5. If we insert a zero at the end of every 4 chips, a new two pairs are also generated.
  • the four complementary codes of four orthogonal complementary code groups each having a code length of 10 are now renumbered and arranged as follows:
  • the eight complementary codes of the four orthogonal complementary code groups each having a code length of 10 may also be kerneled first. :
  • the new orthogonal complementary code group core is expanded once according to the tree structure of the third step.
  • the obtained orthogonal complementary code group pair is obviously the same as the four orthogonal complementary codes shown in Table 6, which means that we You can insert a certain number of zero guard intervals or time slots into the orthogonal complementary code group core, or you can insert zero guard intervals or time slots into the extended spreading address codes with zero correlation windows between groups
  • the inter-group zero correlation window width of the new orthogonal complementary code group thus formed is larger than the inter-group zero correlation window width of the original orthogonal complementary code group.
  • Table 6 shows the correlation function values of the eight complementary codes. From Table 6, it can be seen that the cross-correlation function between the extended sets of spreading address codes has a zero correlation window near the origin, and the width of the window is greater than or Equal to 7; The autocorrelation function of each spreading address code after expansion is zero except for the origin and the relative shift ⁇ is 1 and -1 in the zero correlation window between the groups, and is zero everywhere; the same group is shifted ⁇ 1 and -1 are not zero, others are zero.
  • R 13 (T) R CiC] (T) + R ⁇ (T) 0 0 0 0 0 0 0 0 0 0 0
  • R (T) R CiC4 (T) + R SiS4 (T) 0 0 0 0 0 0 0 0 0 0 0
  • R 15 (T) R CiC5 (r) + R SiS5 (r) 0 0 0 0 0 0 0 0 0 0 0
  • R L7 (T) R CiCi (r) + R SISI (T) 0 0 0 0 0 0 0 0 0 0
  • R 15 (T) R CICS (T) + R S2SS (T)
  • R 15 (T) R C3Cs (r) + R S3S5 (r) 0 0 0 0 0 0 0 0 0 0 0
  • R a1 (T) R C4Ci (T) + R S4Si (T) 0 0 0 0 0 0 0 0 0 0 0
  • R 56 (r) R C5C6 (T) + R SsS6 (T) 0 0 8 0 -8 0 0
  • the second step is to generate or select one or more sets of basic orthogonal complementary code groups X ⁇ according to the width of the required zero correlation window.
  • the pair of basic orthogonal complementary code groups (C 1 7 S x (C 2 , S 2 ) in which each code length is N and the width of the zero correlation window window is L refers to: its autocorrelation and mutual correlation
  • the correlation function is the sum of the non-periodic auto-correlation and cross-correlation functions between the C code and the S-code, and the non-periodic auto-correlation and cross-correlation function between the S code.
  • the periodic autocorrelation and the cross-correlation function are oppositely formed except for the origin, and the value of the autocorrelation function and the cross-correlation function after addition are zero except for the origin.
  • the pair of basic orthogonal complementary code groups (C 15 Si), (C 2 , S 2 ) —A kind of generation method can use the basic orthogonal complementary code group pair generation method of Professor Li Daoben in PCT / CN00 / 00028.
  • the width of the zero correlation window can be selected from FIG. 3 to be greater than or equal to the required width
  • the length of each code of the orthogonal complementary code group core formed after the expansion is 2N, and the width of the zero correlation window between groups is greater than or equal to 2L-1.
  • each code of the pair of basic orthogonal complementary code groups (C p S, (C 2 , S 2 ) in the second step is N and the width of the zero correlation window is L
  • T zeros are inserted for every L + 1 chips (Chip) of the 2N orthogonal complementary code group core, and the zero guard interval or time slot insertion method is used as follows:
  • Each L + 1 chips (Chi p) inserting T zeros at the tail, and the new orthogonal complementary code group kernel formed by the zero-correlation window width of the group is greater than or equal to 2L-1, and thus the new orthogonal complementary code group kernel is as shown in FIG.
  • the tree structure continues to expand, and the width of the zero correlation window between the obtained orthogonal complementary code group pairs is greater than or equal to 2L-1.
  • the criterion for inserting these T zeros is to make the new orthogonal complementary code group kernel thus formed.
  • the width of the zero correlation window between groups is maximized.
  • There are many ways to insert these T zeros for example, the tail of each L + 1 chips (Chi p), and the insertion of each L + 1 chips (Chip). Head, not here-list.
  • the fourth step is to determine the required maximum number of user addresses according to the actual number of users, and use the selected orthogonal complementary code group kernel with a zero correlation window between groups as the origin in FIG. 1 or FIG. 2 in the tree diagram.
  • the code length and the number of codes are extended to expand, and the cross-correlation function between the spread groups of spreading address codes has a zero correlation window between the groups near the origin.
  • the two pairs of basic orthogonal complementary code groups can be separately identified. As the original point in FIG. 1 or FIG. 2, the code length and the number of codes are extended in the tree diagram, and the number of stages to be extended is 5, and the two pairs of basic orthogonal complementary code groups are expanded into a total of 64 groups. A total of 128 address codes can be used as the selected multi-address code. If there are four pairs of basic orthogonal complementary code groups that meet the system design requirements, these four pairs of basic orthogonal complementary code groups can be used as shown in Figure 1 or Figure 2, respectively. The original point of the code length and number of codes are expanded in the tree map, and the number of stages required for expansion is 4.
  • the 64 address codes and 128 address codes can meet the system design requirements; if there are eight pairs of basic codes, The orthogonal complementary code groups meet the system design requirements.
  • the eight pairs of basic orthogonal complementary code groups can be used as the origin in Figure 1 or Figure 1, respectively, and the code length and number of codes are expanded in the tree diagram. The number of extended stages is 3, and the resulting 64 groups of codes with a total of 128 address codes can meet the system design requirements.
  • the 16 pairs of basic orthogonal complementary code groups can be separately identified. As the origin in Figure 1 or Figure 2, the code length and the number of codes are expanded in the tree diagram. The number of stages to be expanded is 2.
  • the 64 address codes and a total of 128 address codes can meet the system design. Requirements; when there are 32 pairs of basic orthogonal complementary code groups that meet the system design requirements, the 32 pairs of basic orthogonal complementary code groups can be used as the origin in Figure 1 or Figure 2, respectively, and the code length and number of codes are respectively performed in the tree diagram. If the number of stages to be expanded is 1, the number of stages required to be expanded is 1, and the resulting 64 groups of codes and 128 address codes can meet the system design requirements. Other user design can be deduced by analogy.
  • Each code position is inverted.
  • Interleave the polarity of each code point For example, (++-+, + ---), (+++-, +-++) can be used to interleave the polarity of each code point, that is, the first of each code, The polarity of the third-order odd digits does not change, and the second and fourth-order even digits change polarity, so (+ ⁇ , ++-+), (+-++, +++-), or odd-numbered digits The polarity is changed, and the even bit is unchanged.
  • ⁇ can be any initial angle.
  • Figure 2 is an equivalent transformation of Figure 1, that is, Figure 2 is formed by moving all the upper half of C1 and S1 in Figure 1 to the left and C2 and S2 to the right. C1 and S1 in all the lower half of FIG. 1 are moved to the right, and C2 and S2 are moved to the left.
  • the code positions of the C code and the S code in the generated multi-address code group can be staggered according to a certain rule, or the polarity can be changed.
  • This kind of transformation is called mathematically equivalent transformation in mathematics. There are many types of equivalent transformations. Please forgive me if I can't list them here.
  • S codes are respectively modulated on mutually orthogonal polarized waves (horizontal and vertical polarized waves, left-handed and right-handed polarized waves).
  • the C code and the S code can be placed separately and still do not overlap each other after transmission.
  • the transmission channel changes randomly over time, to ensure the realization of complementarity, the channel characteristics in the two polarized waves and in the two time slots should be kept consistent during the transmission process. In other words, in engineering description languages, their decline should be synchronized. This requires that when polarized separation is used, a frequency band that can guarantee the simultaneous fading of orthogonally polarized waves without depolarization and corresponding measures must be used.
  • time-division separation the interval between two time slots must be much smaller than The correlation time of the channels must also ensure their synchronous fading when using other separation methods.
  • the invention provides a new method for encoding a spread spectrum multi-address code, so that the correlation characteristics between the groups of the formed spread spectrum multi-address code have a "zero correlation window", that is, each within the zero correlation window Correlation functions and cross-correlation functions between group address codes have no peaks, thereby eliminating multiple access interference between groups
  • inter-group zero-correlation window-based spreading code encoding method provides both the zero-correlation window characteristics and joint detection and interference. Offset technology and equalization technology provide the possibility to increase the system capacity. At the same time, the present invention solves the complexity problem of applying joint detection in the traditional CDMA system.

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Abstract

La présente invention concerne un procédé pour coder et appliquer des codes d'accès multiples à étalement du spectre avec des fenêtres de corrélation intergroupe nulle, par production de la paire de groupes de base de codes complémentaires orthogonaux; étalement de cette paire de groupes de codes complémentaires orthogonaux et production du noyau de groupes de codes complémentaires orthogonaux avec des fenêtres de corrélation intergroupe nulle; étalement de ce noyau de groupes de codes complémentaires orthogonaux avec des fenêtres de corrélation intergroupe nulle; insertion d'une fente ou d'un intervalle de protection nulle dans les codes d'accès à étalement du spectre étalés avec les fenêtres de corrélation intergroupe nulle, puis formation des groupes de codes complémentaires orthogonaux avec des fenêtres de corrélation intergroupe nulle dont la largeur est supérieure à celle des fenêtres de corrélation intergroupe nulle des groupes de codes complémentaires orthogonaux. Cela fait que la propriété de corrélation intergroupe avec 'fenêtres de corrélation nulle' des codes d'accès multiples à étalement du spectre ainsi formés, et par conséquent les lobes latéraux de la fonction de corrélations croisées n'existent pas dans les fenêtres à corrélation nulle entre les groupes de codes d'accès, d'où l'élimination de l'interférence d'accès multiple entre groupes. Enfin, bien qu'il existe dans un même groupe une interférence d'accès multiple entre les codes d'accès, on obtient une réception optimale en utilisant la technique de teste unifiée.
PCT/CN2003/000115 2003-01-31 2003-01-31 Procede pour coder et appliquer des codes d'acces multiples a etalement du spectre avec des fenetres de correlation intergroupe nulle WO2004068760A1 (fr)

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AU2003303842A AU2003303842A1 (en) 2003-01-31 2003-01-31 A method for coding and applying spread spectrum multiple access codes with intergroup zero correlation windows
CN03805482.5A CN1640040A (zh) 2003-01-31 2003-01-31 一种具有组间零相关窗的扩频多址码编码及应用方法
PCT/CN2003/000115 WO2004068760A1 (fr) 2003-01-31 2003-01-31 Procede pour coder et appliquer des codes d'acces multiples a etalement du spectre avec des fenetres de correlation intergroupe nulle

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008092301A1 (fr) * 2007-01-26 2008-08-07 Daoben Li Procédé et système de multiplexage par répartition en code

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1175828A (zh) * 1997-08-12 1998-03-11 李道本 一种扩频地址编码技术
WO2002001759A1 (fr) * 2000-06-26 2002-01-03 Linkair Communications, Inc. Procede de mise en place de groupes de codes d'etalement de spectre orthogonaux

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1175828A (zh) * 1997-08-12 1998-03-11 李道本 一种扩频地址编码技术
WO2002001759A1 (fr) * 2000-06-26 2002-01-03 Linkair Communications, Inc. Procede de mise en place de groupes de codes d'etalement de spectre orthogonaux

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008092301A1 (fr) * 2007-01-26 2008-08-07 Daoben Li Procédé et système de multiplexage par répartition en code

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