CN1640038A

CN1640038A - A method for coding and applying void time spread spectrum multiple access codes

Info

Publication number: CN1640038A
Application number: CN03805480.9A
Authority: CN
Inventors: 邹永忠; 李道本; 张永生; 方莉
Original assignee: Linkair Communications Inc
Current assignee: Linkair Communications Inc
Priority date: 2003-01-31
Filing date: 2003-01-31
Publication date: 2005-07-13
Also published as: AU2003211295A1; WO2004068761A1

Abstract

The present invention provides a method for coding and applying the void time spread spectrum multiple access codes, by generating or selecting a pair or a plurality pairs of the basic orthogonal complemental code groups, in which each code length is N and width of the zero correlation windows is L; spreading the pair of generated to selected basic orthogonal complemental code groups, and obtaining the void time orthogonal complemental code groups kernel with the intergroup zero correlation windows; spreading the code length and number of the said void time orthogonal complemental code groups kernel with the intergroup zero correlation windows, and obtaining the cross-correlation function with the zero correlation windows between the void time access code groups; then the side lobes of the cross-correlation function don't exist in the zero correlation windows between the access code groups, so the multiple access interference between groups is eliminated; in addition the united testing technique, the interference offset technique and the balance technique can be utilized, so it is possible that the capacity of system is improved. Moreover the present invention solves the complication problem about the application of the united testing in the conventional CDMA system.

Description

A method for coding and applying void time spread spectrum multiple access codes

Space-time spread spectrum multi-address code coding and application method technical field

The invention relates to the technical field of spread spectrum and Code Division Multiple Access (CDMA) wireless communication, in particular to a spread spectrum multiple access code with space-time diversity characteristic in a wireless communication system; in particular to a space-time spread spectrum multi-address code coding and application method.

Background of the inventionwith the advent of the information-oriented society and the personal communication era, it is becoming more and more urgent to improve the spectrum efficiency in wireless communication systems because frequency resources are very limited. By spectral efficiency, it is meant the maximum number of users that the system can accommodate in a cell (cell) or sector (sector) given the user signaling rate and system bandwidth, and the unit of measure is the total signaling rate supported by the system per cell (or sector) per unit bandwidth. Clearly, the higher the spectral efficiency, the greater the system capacity.

Traditional wireless multiple access techniques, such as Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA), have system capacity limited by the time-bandwidth product of the system, and additional user additions are not possible at all. For example: the basic signaling rate of a user is 1/T symbol second, the bandwidth of a system (including a channel) is B Hertz (Hertz), the time bandwidth product is BT, and BT is the maximum number of users in the system, and one more BT is not possible.

Code Division Multiple Access (CDMA) is completely different, and its system capacity is only determined by signal-to-interference ratio, and has the characteristics of large capacity and soft capacity, and the increase of users only can reduce signal-to-interference ratio, reduce communication quality and can not be rejected. I.e. the system capacity does not have an unjustifiable limit BT value like Frequency Division Multiple Access (FDMA) or Time Division Multiple Access (TDMA).

The capacity of a Code Division Multiple Access (CDMA) system depends on the interference level within the system, and therefore, the ability to control the interference level within the system becomes a key to the success or failure of the CDMA system. Interference can be divided into four major parts: the method is characterized in that the noise level in the local and system is not provided with other methods except for adopting a low noise amplifier; the second is intersymbol interference (ISI), and the third is Multiple Access Interference (MAI), i.e. interference from other users in the cell; and fourthly, adjacent cell or inter-channel interference (ACI). ISI, MAI, ACI can be reduced or even eliminated by a well-selective address code. In a Code Division Multiple Access (CDMA) system, each user has its own unique address code for identifying each other. Furthermore, the spreading address codes of the users should be mutually orthogonal, and the requirement of orthogonality is consistent for any multiple access system. If the channel is an ideal linear time frequency non-diffusion system' and the interior of the system has strict synchronization relationship, the orthogonality among the address codes of all users can be ensured. But none of the real channels are ideal and tight synchronization is not possible for signals in time, frequency dispersive channels. Therefore, it is a life of Code Division Multiple Access (CDMA) systems to maintain orthogonality among the address codes in non-ideal time-frequency dispersive channels.

As is well known, mobile communication channels are typically random time-varying channels in which there is a random frequency spread (caused by the doppler effect) and a random time spread (caused by the multipath propagation effect). The former will make the received signal produce time selective fading, that is, the received signal level will have different random fluctuation with time; the latter will cause the received signal to undergo frequency selective fading, i.e. the received signal will have different random fluctuation variations for different spectral components. Fading will reduce the capacity of the system substantially, in addition to severely degrading the performance of the system. In particular, time dispersion of the channel due to multipath propagation prevents signals from reaching a receiving point at the same time, and causes signals between adjacent symbols of the same user to overlap each other, thereby causing inter-symbol interference (ISI). In addition, the time dispersion of the channel also deteriorates the multiple access interference, because when the relative delay between different user signals is zero, the orthogonality is easily guaranteed by 4 and any orthogonal code can be used. But when the relative time delay between the signals is not zero, it becomes very difficult to maintain the orthogonality.

To reduce intersymbol interference (ISI), the signal waveform selected by each user, i.e. the autocorrelation function of its address code, should be an ideal impulse function, i.e. it should be zero everywhere except the origin. In order to reduce Multiple Access Interference (MAI), the cross-correlation function between the address codes of the signal waveforms selected by the respective users should be zero at all locations for various relative delays. From the perspective of orthogonality, each spread-spectrum address code should be orthogonal to itself except for the relative zero delay for any non-zero relative delay, and the spread-spectrum address codes should be orthogonal to each other for any relative delay (including zero delay).

For the sake of image, the autocorrelation function values at the origin are referred to as the main peak of the correlation function, and the autocorrelation or cross-correlation function values outside the origin are referred to as the secondary peak of the correlation function. The self-correlation and cross-correlation functions between ideal multiple access codes should have all zero cross-product. Unfortunately, the theoretical Welch bound states that: there is no multiple access code group with zero in the secondary, finite or even complex domain. In particular, the peak-off of the autocorrelation function is a contradiction to the peak-off of the cross-correlation function, and when a decrease in one is required, the other must increase. In addition, the national aerospace administration (NASA) also announces that various codes have been calculated exhaustively and proves that the We 1 ch boundary is not breached.

In fact, the national space administration (NASA) exhaustively computes only group codes, whereas the Welch bound holds only for domains below the complex number, beyond which address codes of an ideal nature are likely to exist. For example, in 1971, schweii tzer, the university of los angeles (UCLA), california, in his doctor paper "generalized complementary Code Sets," a generally miniaturized Code Sets, has found a coding method that achieves the desired address Code set performance. Leppanen, penti et al, from Nokia MOBILE PHONES LTD.; Nokia telecom, Inc., applied their idea to a time division/code division (TDMA/CDMA) hybrid system in 1993 later, and applied for European patent publication EP 0600713A2 with application No. 93309556.4. This type of encoding is actually encoding in a high-dimensional space that has broken the conditions for the Welch bound to hold.However, this coding scheme has extremely low spectral efficiency and no practical value, which is why it has not been used for three decades. Because for a communication system requiring N addresses, the coding scheme requires the use of N²A basic code, each code requiring at least N bits, i.e. a total of N³The bits support N addresses. For example: if the address number N is 128 and 16QAM modulation method is adopted, the corresponding system is determined

ts/Hz (bits/hertz). It can be seen that the larger the number of addresses, the lower the spectral efficiency of this coding scheme. However, this coding method gives a hint of 4 geygen that an address code with good performance can be constructed by a "complementary" method, but the disadvantage that the total number of code bits required by b.p. schweii tzer doctor increases with the third power of the number of addresses must be avoided.

In addition, if a two-way synchronization technique is employed, the relative delays within or between the individual address codes in a random time-varying channel will not exceed the maximum time dispersion of the channel (maximum multipath delay variation) plus the maximum timing error. Assuming that this amount is Δ seconds, it is guaranteed that intersymbol interference (ISI) and Multiple Access Interference (MAI) are zero as long as there is no peak-off in the intersymbol and cross correlation functions in (- Δ, Δ). An address code having such properties is called an address code having a "zero correlation window". Obviously, as long as the correlation characteristics of the address code have a "zero correlation window" and the window width is larger than the maximum time dispersion (maximum multipath delay difference) plus the maximum timing error of the channel, the performance of the corresponding code division multiple access (C ^ MA) system will be ideal, and the fatal "near-far effect" in the traditional Code Division Multiple Access (CDMA) system will disappear. The "near-far effect" is caused by the non-ideal auto-and cross-correlation properties of the address code, since the minor peak of a near signal may overwhelm the major peak of a far signal. To overcome the "near-far effect", the signals of the individual addressed users must be made substantially equal in strength when reaching the base station, which results in the necessity of employing accurate, complex and fast power control algorithms, thereby complicating the system.

In 1997, the li dao professor proposed a new type of spreading code with zero correlation window in PCT/CN00/00028, assuming that the maximum time dispersion (maximum multipath delay difference) of the channel plus the maximum timing error, this quantity is set to △, and this codeword guarantees that the correlation properties within (- Δ, Δ) are ideal.

Assuming that the complementary code set is { C, SJ,1 ≦ M, the code length of the C portion or S portion is N, the single-side zero correlation window width is Γ, according to the zero correlation window boundary: m is less than or equal to^{2N + 2T}So given the code length and the zero window size,

T + 1

the maximum number of codes possible has been determined and it is not possible to find more codewords.

In order to eliminate the influence of interference, besides directly constructing a zero window code during code word design, another method is to transmit a non-zero window code at a transmitting end, and adopt a joint detection technology, an interference cancellation technology and an equalization technology at a receiving end to achieve optimal reception. Assuming that M code channels exist together and g-ary modulation is adopted, the total detection quantity during optimal joint detection is

The complexity of the detection method is exponentially increased along with the number of users m, and when the number of users m is increased, the receiver cannot function, which limits the increase of the system capacity. In order to reduce the complexity of the receiver, some suboptimal joint detection algorithms such as decorrelation multi-user detection, interference cancellation techniques and the like are adopted, but the algorithms bring performance loss, and the complexity is still high when the number of users is large.

Diversity techniques are effective techniques against fading, and the most basic diversity techniques are spatial diversity, frequency diversity and time diversity. The research on Space-time Coding (Space-t ime Coding) started in bell laboratories of 1996, which combines Space diversity, frequency diversity and time diversity, and the existing Space-time Coding mainly includes two types: trellis (Trel is) space-time codes and hierarchical space-time codes. Existing space-time coding can be viewed as a technique that combines spatial diversity, frequency diversity and time diversity techniques with channel coding or with forward error correction coding techniques.

Disclosure of Invention

The invention aims to provide a space-time spread spectrum multiple address code coding and application method, which enables the formed space-time spread spectrum multiple address code groups to have zero correlation windows, namely, the cross correlation function among the address codes in each group in the zero correlation windows has no peak, thereby eliminating the Multiple Access Interference (MAI) among the groups, and the Multiple Access Interference (MAI) exists among the address codes in the same group, but the optimal receiving can be achieved by utilizing the joint detection technology. The space-time spread spectrum code coding method with the inter-group zero correlation window characteristic provided by the invention combines the diversity technology and the zero correlation window characteristic, and can utilize the joint detection, the interference cancellation technology and the equalization technology, thereby providing possibility for increasing the system capacity. Meanwhile, the method solves the complexity problem of application joint detection in the traditional C response A system.

The space-time spread spectrum multi-address code with the inter-group zero correlation window has the following five characteristics:

the cross-correlation function between the space-time spread spectrum address codes of each group has a zero correlation window near the origin. From an orthogonality point of view, the groups of space-time spreading address codes are completely orthogonal when the relative time delay is smaller than the width of the zero correlation window.

And (II) the autocorrelation function of each space-time spread spectrum address code is not zero at two non-zero relative time delays except the origin in the intergroup zero correlation window, and is zero at other positions, namely the autocorrelation function has ideal characteristics.

And (III) the cross-correlation function of each space-time spread spectrum address code in the same group is not zero only at two non-zero relative time delays and is zero at other positions in the zero-correlation window between the groups. (IV) transmitting the code division on two transmitters for each space-time spread spectrum address

And (V) for each space-time spread spectrum address code, the size of the zero correlation window between groups can be increased by inserting a zero guard interval or a time slot.

The technical scheme of the invention is as follows:

a space-time spread spectrum multiple address code coding method is characterized by comprising the following steps: generating or selecting one or more pairs of basic positive interactive code components with the code length of N zero correlation windows and the width of L;

expanding the generated or selected basic orthogonal complementary code group pair to obtain a space-time orthogonal complementary code group kernel with an inter-group zero correlation window;

and expanding the code length and the code number of the space-time orthogonal complementary code group core with the intergroup zero correlation window, wherein the cross-correlation function between the space-time address codes of each group obtained after expansion has the zero correlation window.

The space-time orthogonal complementary code group core with the intergroup zero correlation window can be subjected to zero guard interval or time slot insertion processing, so that the size of the intergroup zero correlation window among the space-time spread spectrum address codes formed after processing is increased.

The selecting a pair of basic orthogonal complementary code sets with each code length being N and the width of a zero correlation window being L comprises: can be provided with: (C S), (C) and (C),₂， S，₂) Is said set of substantially orthogonal complementary codes, and:

C₂₂"'C_2N)，

S₂₂*"^ES_2N),

the non-periodic autocorrelation and cross-correlation functions of the c code and the s code are opposite in phase in a zero correlation window except the origin, and the added autocorrelation function value and cross-correlation function value are zero everywhere except the origin.

Said expanding said set of substantially orthogonal complementary code pairs comprises: according to the actual needed maximum user address number, the orthogonal complementary code kernel is expanded in the spanning tree structure according to the code length and the code number, a related window exists in the cross-correlation function of each group of expanded space-time spread spectrum address codes near the origin, and the window has the value of < 1 > or equal to 2L-1; the autocorrelation function of each space-time spread spectrum address code after spreading is not zero only at two non-zero relative time delays except the origin in the intergroup zero correlation window, and is zero at other positions; the cross-correlation function of each space-time spread spectrum address code in the same group is not zero only at two non-zero relative time delays and is zero at other positions in the above-mentioned intergroup zero correlation window.

Said expanding said set of substantially orthogonal complementary code pairs comprises: for the selected pair of substantially positive reciprocal complement values (C, S), (C,₂, s，₂) Carrying out an expansion, wherein:

C₂₂'"C_2N)，

S，i⁼(S_nS₁₂'"S_1N)， S，₂=(S₂₁S₂₂"'S_2N);

the obtained space-time orthogonal complementary code group kernel with the inter-group zero correlation window is as follows:

the processing of inserting zero guard interval or time slot into the space-time orthogonal complementary code group core with the intergroup zero correlation window or each expanded space-time spread spectrum address code comprises: the size of the intergroup zero correlation window among each group of space-time spread spectrum address codes formed after expansion can be increased by inserting a zero guard interval or a time slot into the space-time orthogonal complementary code group core with the intergroup zero correlation window or each space-time spread spectrum address code after expansion.

When the space-time spread spectrum address code is operated, the C code is only operated with the C code (including self code and other codes), and the S code is only operated with the S code (including self code and other codes).

The pair of substantially orthogonal complementary codes (CpS, (C)₂, S₂) The method comprises the following steps: the autocorrelation and cross-correlation functions are respectively the sum of the aperiodic autocorrelation and cross-correlation functions between C codes and the aperiodic autocorrelation and cross-correlation functions between S codes, wherein in a zero correlation window, the aperiodic autocorrelation and cross-correlation functions of the C codes and the S codes are opposite except for the origin, and the added values of the autocorrelation function and the cross-correlation function are zero everywhere except for the origin.

The space-time orthogonal complementary code group kernel with the inter-group zero correlation window refers to: the length of each code of the space-time orthogonal complementary code group core formed after the expansion is 2N, and the width of the inter-group zero correlation window is more than or equal to 2L-1. The zero guard interval or time slot inserted into the space-time orthogonal complementary code group core of the inter-group zero correlation window means that: firstly, the basic orthogonal complementary code pair (C) with each code length of N and zero correlation window width of L is used^? _{1 ?}) ( C，₂， S，₂), C'₁= (C₁₁C^ ^-C^) , C，₂= (C₂₁C₂₂"·_2Ν)， S⁹^ (S₁₃S₁₂〜S_1N；)， S'₂= (S₂₁S₂₂... S_2N) The code length is 2N, the width of the inter-group zero correlation window is 2L-1,

- C_2IC₂₂- C₂₂' .'C_2N-S_2tS₂₂- S₂₂...s.

then, a certain number of zero guard intervals or time slots can be inserted into the space-time orthogonal complementary code group core, so that the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group core is greater than or equal to the inter-group zero correlation window width of the original space-time orthogonal complementary code group core.

The zero guard interval or time slot inserted into the space-time orthogonal complementary code group core of the inter-group zero correlation window means that: inserting T zeros every L +1 chips (Chip), wherein the inter-group zero correlation window width of a new space-time orthogonal complementary code group kernel formed by inserting T zeros is larger than or equal to 2L-1, the new space-time orthogonal complementary code group kernel continuously expands according to a tree structure, and the inter-group zero correlation window width of the obtained space-time orthogonal complementary code group pair is larger than or equal to 2L-1:

the expanding of the code length and the code number of the space-time orthogonal complementary code group core in the spanning tree structure refers to: if (C)_{p t}), ( C₂, S₂) If a pair of space-time orthogonal complementary code group kernels with each code length being N and a zero correlation window width being L is used, two pairs, that is, four groups of space-time orthogonal complementary code group pairs with each code length being 2N can be generated as follows:

(C_vc₂, s_i;s₂)

and a zero correlation window exists in the interclass cross correlation function of the two pairs of space-time orthogonal complementary code pairs formed by the expanded upper and lower branches near the origin, and the window width is greater than or equal to L. Two pairs of orthogonal complementary code pairs formed by an upper branch and a lower branch can be regarded as two pairs of codes with the length of each code being

2N orthogonal complementary code groups with the width of the zero correlation window larger than or equal to L, continuously expanding to obtain four pairs of space-time orthogonal complementary code groups, wherein a zero correlation window exists in the vicinity of the origin of the interclass cross correlation function of the four pairs of space-time orthogonal complementary code groups, and the window width of the zero correlation window is larger than or equal to L

The expansion may continue in a spanning tree structure to produce a code length of N2ⁿInter-group zero correlation window width greater than or equal to 2 of LⁿThe pair of space-time orthogonal complementary code pairs, where n =0, 1, 2.·, is the number of spreading.

The step of inserting zero guard interval or time slot into each extended space-time spread spectrum address code with inter-group zero correlation window is as follows: and inserting a certain number of zero guard intervals or time slots into each space-time spread spectrum address code which is generated by the core expansion of the space-time orthogonal complementary code group and has an inter-group zero correlation window, wherein the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group is larger than or equal to the inter-group zero correlation window width of the original space-time orthogonal complementary code group.

If each extended group of space-time spread spectrum address codes has a zero correlation window with the inter-group width of 2W-1, inserting T zeros for every W chips (chips) of each extended group of space-time spread spectrum address codes; the inter-group zero correlation window width of the new space-time orthogonal complementary code group thus formed is greater than or equal to 21. The insertion of the T zeros needs to satisfy the following conditions: and maximizing the inter-group zero correlation window width of the formed new space-time positive interactive complementary code group.

Said intervening Gamma zeros include: t zeros are inserted at the tail of every L +1 chips (Chip), T zeros are inserted at the head of every L +1 chips (Chip), and so on. The invention also provides a space-time spread spectrum multi-address code application method, which comprises the following steps: determining the width of the required intergroup zero correlation window according to the propagation condition of the applied system, the basic spread spectrum code rate adopted by the system and the maximum timing error in the system;

generating or selecting one or more pairs of basic orthogonal complementary code pairs according to the width of the intergroup correlation window of the required zero;

expanding the basic orthogonal complementary code group pair to generate a space-time orthogonal complementary code group kernel with an intergroup zero correlation window;

determining the required maximum user address number according to the number of the actual users, taking the selected core of the space-time orthogonal complementary code with the zero correlation windows among the groups as an origin, expanding the code length and the code number in a spanning tree structure, and enabling cross correlation functions among the expanded space-time spread spectrum address codes of each group to have an inter-group zero correlation window near the origin;

and respectively carrying out spread spectrum modulation transmission on each group of the expanded space-time spread spectrum address codes with the intergroup zero correlation windows on corresponding transmitters.

The generating and selecting the basic orthogonal complementary code pair comprises the following steps: selecting the basic orthogonal complementary code pair (d, S, C) with code length N and zero correlation window width L₂， S₂) Said (, S)_t)、 (C₂， S₂) The autocorrelation and cross-correlation functions of the code C and the code S are respectively the sum of the aperiodic autocorrelation and cross-correlation functions between the code C and the code S and the aperiodic autocorrelation and cross-correlation functions between the code S and the code C, wherein in a zero correlation window with the width of L, the aperiodic autocorrelation and cross-correlation functions of the code C and the code S are opposite to each other except the origin, and the added autocorrelation function values and cross-correlation function values are zero everywhere except the origin.

The generating and selecting the basic orthogonal complementary code pair comprises the following steps: the basic orthogonal complementary code pair (C)_pS , ( C₂, S₂) May be generated using a spanning tree structure. The expanding the basic orthogonal complementary code group pair to generate the space-time orthogonal complementary code group kernel with the zero correlation windows among the codes comprises: for the obtained basic orthogonal complementary code pair group ((^ Si), (C) with each code length N and zero correlation window width L₂， S₂) And expanding the space-time orthogonal complementary code group kernel with the intergroup zero correlation window in the following way, wherein: CfCCu CfC ^: ) C, C₂=(C₂₁

The length of each code of the expanded space-time orthogonal complementary code group kernel is 2N, and the width of the inter-group zero correlation window is more than or equal to 2L-1.

According to the method of the invention, a certain number of zero guard intervals or time slots are inserted into the space-time orthogonal complementary code group core,

the width of the correlation window is larger than the width of the intergroup zero correlation window of the original space-time orthogonal complementary code group kernel.

According to the method of the present invention, if the pair of substantially orthogonal complementary codes (, S,), (C)₂， S₂) The length of each code is N and the width of the zero correlation window is L, then T zeros can be inserted into every L +1 chips (chips) of the extended space-time orthogonal complementary code group kernel with the length of 2N, wherein T zeros can be inserted into the tail of every L +1 chips (chips), the width of the intergroup zero correlation window of the formed new space-time orthogonal complementary code group kernel is equal to or larger than 2L-1, the new space-time orthogonal complementary code group kernel is continuously extended according to a spanning tree structure, and the width of the intergroup zero correlation window of the obtained space-time orthogonal complementary code group kernel is larger than or equal to 2L-1.

The insertion of the T zeros needs to satisfy the following conditions: maximizing the inter-group zero correlation window width of the formed new space-time positive interaction ^ code group core.

The inserting of the T zeros comprises: t zeros are inserted at the tail of every L +1 chips (Chip), T zeros are inserted at the head of every L +1 chips (Chip), and so on.

And the expansion stage number required in the spanning tree is determined according to the required maximum user number and the group number of the selected basic orthogonal complementary code pair group. The spread spectrum modulation transmission of each group of the extended space-time spread spectrum address codes with the intergroup zero correlation windows on the corresponding transmitters respectively comprises the following steps: there may be two transmitters for the same group with an inter-group zero correlation window.

The spread spectrum modulation transmission of each group of the extended space-time spread spectrum address codes with the intergroup zero correlation windows on the corresponding transmitters respectively comprises the following steps: the two different transmitters can be respectively corresponding to the groups with the inter-group zero correlation window.

The spread spectrum modulation transmission of each group of the extended space-time spread spectrum address codes with the intergroup zero correlation windows on the corresponding transmitters respectively comprises the following steps: when the following two groups of space-time orthogonal complementary code sets are adopted:

S_NS₁₂S₁₂•SIN S_1N

" C_uC₁₂- C₁₂... C_1N- C - S_NS₁₂- S₁₂,••SIN _ S_1N

transmitting each group code of the two groups of space-time orthogonal complementary code groups on two transmitters, wherein the two groups can correspond to the same two transmitters or two different groups of two transmitters; the corresponding relations between the two space-time orthogonal complementary codes in the same code and the two transmitters are as follows: for a first space-time orthogonal complementary code, transmitting all odd chips (chips) corresponding to corresponding odd chips at a first transmitter and transmitting all even chips (chips) corresponding to corresponding even chips at a second transmitter; for all odd chips (chips) of the second space-time orthogonal complementary code corresponding to the corresponding odd chips transmitted at the second transmitter, and all even chips (chips) corresponding to the corresponding even chips transmitted at the first transmitter; or vice versa, i.e. all odd chips (Chip) for the second space-time orthogonal complementary code are transmitted corresponding to the odd chips at the first transmitter, and all even chips (Chip) are transmitted corresponding to the even chips at the second transmitter; all odd chips (chips) for the first space-time orthogonal complementary code correspond to corresponding odd Chip transmissions at the second transmitter and all even chips (chips) correspond to corresponding even Chip transmissions at the first transmitter.

The space-time orthogonality refers to: when each space-time spread spectrum address code of the two groups of space-time orthogonal complementary code groups is transmitted on two transmitters to form two groups of four space-time sequences, the two groups of space-time sequences keep orthogonal between groups and have zero correlation windows between the groups,

wherein:

t = a cos(2¾T ^ + , a₂= a₂cos(27_ct + φ₂) ? a₃=₃cos(27_ct + φ_ζ, a₄=₄008(2^^ + ^₄) ? a_{1 ? 25 3 5 4}6 [0₃+oo)_?φ_ι,φ₂,φ_{3 7}φ₄€ [0 mobile phone, can carry out equivalent transformation to the generated multi-address code.

The equivalent transformation may include: swapping the positions of C and S codes, swapping the positions of C1 and C2 and S1 and S2 simultaneously, inverting the code order, inverting each code bit, interleaving the polarity of each code bit, rotating each code bit in the complex plane, changing in the spanning tree, and the like.

The rotating change of each code bit in the complex plane comprises the following steps: the basic complementary code group can be rotated by 'degree' for each code bit sequence, the properties of autocorrelation function and cross-correlation function of each address code after rotation transformation are unchanged, but the secondary peak outside 'zero correlation window' is related to the rotation angle, and the rotation angle can be properly selected to make the rotated code groups orthogonal, i.e. a group of orthogonal codes can be used to produce several groups of orthogonal codes.

The generated multiple groups of orthogonal codes are suitable for the networking requirements, the switching requirements, the capacity increasing requirements and the like; especially when the code length is long.

The orthogonal complementary codes must ensure that the C code operates only with the C code (including self and other codes) and the S code operates only with the S code (including self and other codes). In practical application, a separation measure should be taken for the C code and the S code.

The separation means may include: respectively modulating the C code and the S code on mutually orthogonal polarized waves; or the c code and the S code can be respectively placed in two time slots which are not overlapped after being transmitted.

In the method of the present invention, the transmission channel has random variation with time, and in order to ensure the realization of complementarity, the channel characteristics in two polarized waves and in two time slots should be kept consistent in the transmission process, that is: their fades should be synchronized; this requires that when polarization separation is used, a frequency band and corresponding measures must be used to ensure synchronous fading and no depolarization of orthogonal polarized waves, when time division separation is used, the interval between two time slots must be much shorter than the correlation time of the channel, and when other separation methods are used, synchronous fading must be ensured.

In the method of the present invention, since the C code and the S code should be transmitted separately and at the same time, the complementarity of them is used, the information bits modulated on them should be the same, and the outputs after despreading and demodulating the C code and the S code should be added.

The invention has the advantages that the correlation characteristics between the groups of the formed space-time spread spectrum multi-address codes have a zero correlation window by providing the space-time spread spectrum multi-address code coding and application method, namely, the cross-correlation function between the address codes of each group in the zero correlation window has no peak, thereby eliminating the Multiple Access Interference (MAI) between the groups, and although the Multiple Access Interference (MAI) exists between the address codes in the same group, the optimal receiving can be achieved by utilizing the joint detection technology. The space-time spread spectrum code coding method with the inter-group zero correlation window characteristic provided by the invention combines the diversity technology and the zero correlation window characteristic, and can utilize the combined detection, the interference cancellation technology and the equalization technology, thereby providing possibility for increasing the system capacity. Meanwhile, the invention solves the complexity problem of applying combined detection in the traditional CDMA system. The space-time spread spectrum multiple address code with the zero correlation window has the following five characteristics: the cross-correlation function between the space-time spread spectrum address codes of each group has a zero correlation window near the origin. From an orthogonality point of view, the groups of space-time spreading address codes are completely orthogonal when the relative time delay is smaller than the width of the zero correlation window. And (II) the autocorrelation function of each space-time spread spectrum address code is not zero at two non-zero relative time delays except the origin in the intergroup zero correlation window, and is zero at other positions, namely the autocorrelation function has ideal characteristics. And (III) the cross-correlation function of each space-time spread spectrum address code in the same group is not zero only at two non-zero relative time delays in the intergroup zero-correlation window, and is zero at other positions. (IV) transmitting the code division of each space-time spread spectrum address on two transmitters; and (V) for each space-time spread spectrum address code, the size of the zero correlation window among groups can be increased by inserting a zero guard interval or a time slot.

Drawings

FIG. 1 is the fourth "" graph of space-time orthogonal complement windows H « with meta-windows of the present invention.

FIG. 2 is a second diagram of space-time orthogonal complementation with inter-group correlation window according to the present invention.

FIG. 3 is a graph of quadrature complementary graphs of microspheres of the present invention a 7 microspheres.

The present invention will be described in detail below with reference to examples and the accompanying drawings.

First, generating and selecting a basic orthogonal complementary code pair.

The technical scheme of the invention is that each code length is N, and the width of a zero correlation window is L, and the basic orthogonal complementary code pair (CpSi (C) is₂, S₂) The method comprises the following steps: the autocorrelation and cross-correlation functions are the sum of the aperiodic autocorrelation and cross-correlation functions between C codes and S codes, respectively, wherein in a zero correlation window with a width L, C isThe aperiodic autocorrelation and cross-correlation functions of the code and the S code are formed in opposite directions except the origin, and the added autocorrelation function value and cross-correlation function value are zero everywhere except the origin. The basic orthogonal complementary code pair (C, Si) (C)₂, S₂) One generation method may be the generation method of the basic orthogonal complementary code pair set of li-dao in PCT/CN 00/00028.

It should be noted that, for the orthogonal complementary codes, when performing correlation or matched filtering operation, the C code only operates with the C code, the S code only operates with the S code, and the C code and the S code do not meet each other during operation.

Referring to fig. 3, a spanning tree diagram of a basic complementary code pair group is shown. The pair of substantially orthogonal complementary codes of fig. 3 can be utilized in a specific multi-address encoding process. In the figure, a pair of code groups in any code group is a pair of basically orthogonal complementary code groups, and the complementary autocorrelation function and the cross-correlation function of the pair of code groups have no peak at all, namely have completely ideal characteristics. It should be noted that fig. 3 only generates a basic complementary code pair, and there are many equivalents, such as exchanging their top and bottom, or left and right, reversing their front and back, inverting the space between bits, rotating in complex plane, etc. Equivalent bowl complement codes are available. Their auto-correlation contribution and Λ correlation contribution are also 4 x thought.

Second step, generating space-time orthogonal complementary code group kernel with intergroup zero correlation window

For each pair of substantially orthogonal' complementary codes of length N and width L of the zero correlation window obtained in the first step (C S (C,₂， S，₂), 0Ί= (C_nC₁₂...C_1N), C，₂=(C₂₁C₂₂...C_2N), S =(S_nS₁₂...S_1N)， s，₂=(s₂₁S₂₂...S_2N) Expanding the space-time orthogonal complementary code group kernel with the intergroup zero correlation window in the following way:

i

the length of each code of the expanded space-time orthogonal complementary code group core is 2N, and the width of the inter-group zero correlation window is more than or equal to 2L-1.

The space-time orthogonality refers to that when each space-time spread spectrum address code division of the space-time orthogonal complementary code group core is transmitted on two transmitters to form four space-time sequences of two groups, the two groups of space-time sequences are kept orthogonal and have an intergroup zero correlation window

Wherein a is_x=_xcos(2/_ct + φ_χ)_{7 2}= a₂cos(27_ct + φ₂)₃a₃=₃cos(2¾T_ci + φ₃)₃a₄= a cos(27_ct + φ₄) , α_λ,α₂α e [0, + oo), cpm [ identical to [0 ] mobile, we can insert a certain number of zero guard intervals or time slots into the space-time orthogonal complementary code group cores, so that the inter-group zero correlation window width of the new space-time orthogonal complementary code group core formed by the zero guard intervals or time slots is larger than or equal to the inter-group zero correlation window width of the original space-time orthogonal complementary code group core_{1 ?}Si ), ( C₂, S₂) Each code length of N and the width of the zero correlation window of L, then T zeros can be inserted into every L +1 chips (chips) of the extended code length 2N space-time orthogonal complementary code group kernel. The following zero guard interval or slot insertion method is adopted: and inserting T zeros at the tail of every L +1 chips (Chip), wherein the width of an intergroup zero correlation window of the formed new space-time orthogonal complementary code group core is greater than or equal to 2L-1, the new space-time orthogonal complementary code group core is continuously expanded according to the tree structure of the third step, and the width of the intergroup zero correlation window of the obtained space-time orthogonal complementary code group pair is greater than or equal to 2L-1. The criterion for inserting these T zeros is to make the new space-time positive formed therebyThe inter-group zero correlation window width of the complementary code group kernel is maximized, and the method of inserting T zeros is a robust method, for example, the method is inserted at the tail of every L +1 chips (Chip) and inserted at the head of every L +1 chips (Chip), which is forbidden to enumerate here.

For example, we select the following set of basic positive inter-codes with code length of 1 and window width of zero correlation window of 3:

(C, S) = (+ +, + -) and (C,₂, S，₂) = ( - +, ―)

the space-time orthogonal complementary code set kernel with the inter-group zero correlation window generated according to the above generation method is:

\\/- \ ++ \ „ I one by one

C ) S

And a third step of spreading the code length and the code number of the space-time orthogonal complementary code group kernel which is generated in the second step and has the intergroup zero correlation window, wherein a zero correlation window exists near the original point of the cross correlation function among the extended groups of space-time spread spectrum address codes.

Two pairs or two groups of space-time orthogonal complementary codes with the length of 2N can be generated by the space-time orthogonal complementary code group kernel according to the following modes: (C, C)₂, S, S₂)

(C₂- ， S₂-S_t)

Because two pairs or two groups of four new space-time positive mutual complementary codes can be obtained from one pair of space-time orthogonal complementary codes, but the length of each code is doubled, four pairs or four groups of eight new space-time orthogonal complementary code groups can be derived from the two pairs or two groups of four new space-time orthogonal complementary codes, and then eight pairs or eight groups of sixteen space-time orthogonal complementary codes, wherein the cross correlation function of the code groups between the pairs has a zero correlation window, and the width of the window is related to the original basic complementary code group. This process can be described by a spanning tree diagram relationship, one of which is shown in FIG. 1 and another of which is shown in FIG. 2. There are many other spanning trees, and the relationship between them is equivalent transformation, and the equivalent transformation does not change the width of zero correlation window between groups, but can change the height and distribution of the peak outside the zero correlation window. For example, we select the following code length 4 space-time orthogonal complementary code set kernels:

after once spreading according to the above spreading method, we obtain two pairs, i.e. four groups of space-time orthogonal complementary code sets each having a code length of 8:

for the above two pairs of 8 complementary codes, i.e., four sets of space-time orthogonal complementary code sets each having a code length of 8, they are renumbered as follows:

(CI, S1) = (+ + + + - - + +, + + )；

(C2, S2) = (+ - + - - + + -, + - - + - + - +)；

(C3, S3) = (+ + + + + + - - , + +—— + + + +)；

(C4, S4) = (+ - ++ _ one + + -, - + - ++ -);

(C5, S5) = (—— + + + + + +, + +—— )；

(C6, S6) = (++++++ -, one + - +++ -);

(C7, S7) = ( - - + + ， + +)；

(C8, S8) = (- ++ -one +++, - + - ++ - + -);

when the four groups of 8 complementary codes of the space-time orthogonal complementary code group with the code length of 8 respectively form four groups of 8 space-time sequences with four groups of two transmitters, the four groups of sequences keep orthogonality and have a group zero correlation window:

(C，l， S'l) = ία_λα₂α_χα₂~α_χ― α₂α α₂? α_χα₂—α_χ—α₂—α —α₂-_χ~α₂); (C，2， S'2) = ( α₂~α_λα₂-α_χ—α₂α_λα₂-α_{? α₂~α_χ-α₂α_χ-α₂α_λa₂α_λ);

(C，3， S，3) = ( α₃ ^α4^α3^α4^α3^α4 ~^α3 ~^{α 3 α}3^β4 ~^β3 ~^U4^β3^{α fl}3^Ω4 ^

(C'4, S³4) ~ ( α₄~α₃α₄-₃α₄-α₃~α_{4 3}, α₄-α —₄α₃α ~α₃α₄-α₃)； (C，5， S'5) = ( -₅—₆α₅α₆α₅α₆α₅α₆, -α₅-α₆-α₅—α₆α₅α₆-α₅— α₆); ( 6, S'6)= ( ~α_βα₅α_β~α₅α₆—α₅α₆~α₅， —α₆α₅—α₆α₅α₆-α₅—α₆α₅)； (C7， S7) = ( -α_Ί—α₈α_Ία₈-α_Ί—₈~α_Ί-α_%α_Ί— α&—α_Ί-₈-α_Ί—₈α_Ία_Β)； (C，8， S⁵8) = (—₈α_Ία — α_Ί-α₈α_Ί—α_Βα_Ί, —α_ζα_Ί—₈α_Ί—α_%α_Ία - α), wherein = α_{cos(27f_ct + φ.)， α· e [0₃+οο)_?^. e [0₇2 pi), 2, 3, 4, 5, 6, 7, 8. The cross-correlation function of these four groups of 8 space-time orthogonal complementary sequences can be proof for any ^ 0, + omicron),_e[0，2r) ( ί=1， 2， 3， 4, 5, 6， 7_?8) the self-correlation function of each spread spectrum address code after expansion is zero at other places except the origin and the relative shift tau is 1 and-1 in the intergroup zero correlation window; the cross-correlation function of two spreading address codes within the same group is not zero within the above-mentioned intergroup zero correlation window only at two relative shifts τ of 1 and-1, and is zero elsewhere.

And fourthly, periodically inserting a certain number of zero guard intervals or time slots into each expanded space-time spread spectrum address code with the interclass zero correlation windows, wherein the width of the interclass zero correlation windows of the new space-time orthogonal complementary code group formed by the method is larger than that of the interclass zero correlation windows of the original space-time orthogonal complementary code group.

If the width of the intergroup zero correlation window of the space-time orthogonal complementary code group obtained by the third step is as follows

2L-1, then we can insert T zeros every L +1 chips (Chip), and the inter-group zero correlation window width of the new space-time orthogonal complementary code group thus formed is 2L-1. The criterion for inserting the T zeros is to maximize the inter-group zero correlation window width of the new space-time orthogonal complementary code group formed thereby, and the method for inserting the T zeros is multiple, for example, is inserted at the tail of every L +1 chips (Chip), and is inserted at the head of every L +1 chips (Chip), where it is forbidden to enumerate.

For example, for the two pairs, i.e., four groups of 8 complementary codes of the space-time orthogonal complementary code set with each code length being 8, generated in the third step:

(Cl， SI) = (+ + + + - - + +, + + );

(C2, S2) = (+ - + - - + + -, + - - + - + -+)；

(C3， S3) = (+ + + + + +——， + +—— + + + +)；

(C4, S4) = (+ - + - +—— +， +—— + + - + - )；

(C5, S5) = (—— + + + + + +, + +—— )；

(C6, S6) = (- + + - + - + - , - + - + +—— + )；

(C7, S7) = ( - - + + ， + +);

(C8, S8) = (- + + - - + - + , - + - + - + + - )；

the four groups of code length 8 space-time orthogonal complementary code groups have a zero correlation window width of 5, and if we insert 1 zero at the tail of every 4 chips (Chip), then we generate new two pairs of 8 complementary codes, i.e. four groups of space-time positive interactive complementary code groups each having a length of 10 (if the effective length of zero is not considered to be 8), and they are renumbered as follows:

(Cl， Sl) = (+ + + + 0 - - + + 0 , + + - - 0 0 );

(C2, S2) = (+ - + - 0 - + + - 0 , + - - + 0 - + - + 0 )；

(C3, S3) = (+ + + + 0 + + - - 0 , + + - - 0 + + + + 0 )；(C4， S4) = (+ - + - 0 +—— + 0 +—— + 0 + - + - 0 )；

(C5, S5) = (- - + + 0 + + + + 0 0 + +—— 0 )；

(C6, S6) = (- + + - 0 + - + - 0 - + - + 0 +—— + 0 )；

(C7， S7) = ( - - + + 0 0 0 —— + + 0 )；

(C8, S8) = (— +++ -0- + - + 0- ++ -0);

these four groups of 8 complementary codes of space-time orthogonal complementary code set with each code length being 10 (if zero is not considered and its effective length is 8), the following space-time orthogonal complementary code set cores with each code length being 4 can be first used:

for the space-time orthogonal complementary code group kernel, we can insert 1 zero every 4 chips (Chip), according to the following zero guard interval or slot insertion mode: inserting 1 zero at the tail of every 4 chips (Chip), and the inter-group zero correlation window width of the new space-time orthogonal complementary code group kernel formed thereby is 7, as follows:

therefore, the new space-time orthogonal complementary code group kernel is once expanded according to the tree structure of the third step, and the obtained orthogonal complementary code group pair is obviously identical to the 8 complementary codes of the space-time orthogonal complementary code group with the length of 10. Namely, the inter-group zero correlation window width of a new space-time orthogonal complementary code group formed by inserting each space-time spread spectrum address code into the orthogonal complementary code group core and inserting a zero guard interval or a time slot is larger than that of the original space-time orthogonal complementary code group.

The cross correlation function of the four groups of 8 space-time orthogonal complementary codes has a zero correlation window near the origin, the width of the window is greater than or equal to 7, the autocorrelation function of each space-time spread spectrum address code after expansion is 1 and-1 pa except the origin in the inter-group zero correlation window and the relative shift tau, and the others are zero; the cross-correlation function of two space-time spreading address codes in the same group is not zero in the zero correlation window between groups only at two relative shifts of 1 and-1, and is zero elsewhere.

The generation of the spreading address code of the present invention is described as follows:

first, the width of the required zero correlation window is determined according to the propagation conditions of the applied system, the basic spreading code rate (referred to as the chirp rate in MCPS) used by the system, and the maximum timing error in the system.

And secondly, generating or selecting one or more groups of basic orthogonal complementary code pairs according to the width of the required zero correlation window.

The invention adopts the technical proposal that each code length is N, and the width of a zero correlation window is L, and the basic orthogonal complementary code pair (C) is formed by_pSi ( C₂， S₂) The method is characterized in that the autocorrelation function and the cross-correlation function are respectively the sum of the aperiodic autocorrelation and the cross-correlation function between C codes and the aperiodic autocorrelation and the cross-correlation function between S codes, wherein in a zero correlation window with the width of L, the aperiodic autocorrelation and the cross-correlation function of the C codes and the S codes are formed in an opposite way except for the origin, and the added autocorrelation function value and cross-correlation function value are zero everywhere except for the origin. The basic orthogonal complementary code pair (C)₁₅Si )、 ( C₂, S₂) One generation method may be the generation method of the basic orthogonal complementary code pair set of the li dao professor in PCT/CN 00/00028. For example, any one or more pairs of substantially orthogonal complementary code pair groups having a zero correlation window width greater than or equal to the required width may be selected from fig. 3 as the substantially orthogonal complementary code pair group.

Thirdly, for each basic orthogonal complementary code pair (C) with the code length of N and the width of the zero correlation window of L obtained in the second step₁( C₂, S₂)，

C₂₂...C_2N) , S₁= (S S₁₂...S_1H) , S₂= (S₂₁S₂₂...S_2N) Expanding the space-time orthogonal complementary code group kernel with the intergroup zero correlation window in the following way:

Q

- CJJ C₁₂- C_]2... C_M- C_IN/ - S₁₂...S_1NS₂₁S₂₂S₂₂,

2 •C2N **C_2N-S₂₁S₂₂-S₂₂...s 2N ■s 2N

A certain number of zero guard intervals or time slots can be inserted into the space-time orthogonal complementary code group core, so that the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group core is larger than that of the original space-time orthogonal complementary code group core. If the basic positive interactive code pair in the second step (C)₁₅Si). (C₂, S₂) Each code length of N and the width of the zero correlation window of L, then T zeros may be inserted into every L +1 chips (chips) of the space-time orthogonal complementary code group kernel with each code length of 2N after spreading, according to the following zero guard interval or time slot insertion manner: inserting T zeros at the tail of every L +1 chips (Chip), wherein the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group core is greater than or equal to 2L-1, the new space-time orthogonal interactive complementary code group core is continuously expanded according to the tree structure shown in FIG. 1, and the inter-group zero correlation window width of the obtained space-time orthogonal complementary code group pair is greater than or equal to 2L-1. The criterion for inserting the T zeros is to maximize the inter-group zero correlation window width of the new space-time orthogonal complementary code component kernel formed thereby, and many methods are used for inserting the T zeros, for example, the T zeros are inserted at the tail of every L +1 chips (Chip) and at the head of every L +1 chips (Chip), where the T zeros are not allowed to be listed.

And step four, determining the required maximum user address number according to the number of the actual users, taking the selected space-time orthogonal complementary code group core with the intergroup zero correlation window as the origin point in the graph 1 or the graph 1, expanding the code length and the code number in the tree graph, and enabling the cross correlation function between the expanded space-time spread spectrum address codes of each group to have an intergroup zero correlation window near the origin point.

The spreading will be based on the maximum number of users and the selected basic orthogonal complementary code setThe number of groups of pairs together determines the number of extension stages required in fig. 1 or fig. 2, for example, the maximum number of users required is 120, if only one pair of basic orthogonal complementary code groups meets the system design requirement, since 2 is the number^fi=64>120/2, the number of stages to be extended is 6, and 128 address codes in the 6 th stage of fig. 1 or 2, which is 26=64 group codes, can be used as the selected multi-address code. At this time, the actual maximum number of user addresses is 128, which is larger than the required number of users 120, and the requirement can be completely met; if two pairs of basic orthogonal complementary code groups meet the design requirements of the system, the two pairs of basic orthogonal complementary code groups can be respectively used as the origins in fig. 1 or fig. 2, and the code length and the number of codes are respectively expanded in a tree diagram, the number of stages required to be expanded is 5, and the two pairs of basic orthogonal complementary code groups are jointly expanded into 128 address codes of 64 code groups and can be used as the selected multiple address codes; if there are four pairs of basic orthogonal complementary code groups which meet the system design requirements, the four pairs of basic orthogonal complementary code groups can be respectively used as the origins in fig. 1 or fig. 1, and the code length and the code number are respectively expanded in the tree graph, the number of the stages required to be expanded is 4, and the obtained 64 code groups can meet the system design requirements; if eight pairs of basic orthogonal complementary codes meet the system design requirements, the eight pairs of basic orthogonal complementary codes can be respectively used as the origins in fig. 1 or fig. 2, and the code length and the number of codes are respectively expanded in a tree diagram, so that the number of stages required to be expanded is 3, and the obtained 64 groups of codes totally 128 address codes can meet the system design requirements; when 16 pairs of basic orthogonal complementary codes meet the system design requirements, the 16 pairs of basic orthogonal complementary codes can be respectively used as the origins in fig. 1 or fig. 1, the code length and the code number are respectively expanded in a tree diagram, the number of stages required to be expanded is 2, and the obtained 64 groups of codes totally 128 address codes can meet the system design requirements; when there are 32 pairs of basic orthogonal complementary code sets meeting the system design requirement, the 32 pairs of basic orthogonal complementary code sets can be respectively used as the original points in fig. 1 or fig. 2, and the code length and the number II of the basic orthogonal complementary code sets are respectively expanded in a tree diagram, so that the number of the stages needing to be expanded is 1, and the 64 groups of codes totally 128 address codes can meet the system design requirement.Other user number designs may be analogized.

And fifthly, respectively corresponding each group of the expanded space-time spread spectrum address codes with the intergroup zero correlation windows to the corresponding two transmitters for spread spectrum modulation and transmission.

We take the following two sets of space-time orthogonal complementary code sets as an example

S_nS₁₂S₁₂...S_1NS_1N

- S_uS₁₂- S₁₂.. 'S_1N- S_lN/

For each group of codes described above, the two transmitters are configured to transmit on two transmitters, and two transmitters (for example, downlink) that are the same or two different groups of codes are respectively configured to transmit on two transmitters (for example, uplink).

The corresponding relations between the two space-time orthogonal complementary codes in the same code and the two transmitters are as follows: for a first space-time orthogonal complementary code, transmitting all odd chips (chips) corresponding to corresponding odd chips at a first transmitter and transmitting all even chips (chips) corresponding to corresponding even chips at a second transmitter; for all odd chips (chips) of the second space-time orthogonal complementary code corresponding to the corresponding odd chips transmitted at the second transmitter, and all even chips (chips) corresponding to the corresponding even chips transmitted at the first transmitter; or vice versa, i.e. for the second space-time orthogonal complementary code, all odd chips (chips) correspond to the corresponding odd Chip transmissions at the first transmitter, and all even chips (chips) correspond to the corresponding even Chip transmissions at the second transmitter; all odd chips (chips) for the first space-time orthogonal complementary code correspond to corresponding odd Chip transmissions at the second transmitter and all even chips (chips) correspond to corresponding even Chip transmissions at the first transmitter.

The space-time orthogonality refers to that when each space-time spread spectrum address code of the two groups of space-time orthogonal complementary code groups is transmitted on two transmitters to form two groups of four space-time sequences, the two groups of space-time sequences keep orthogonal and have zero correlation windows between the groups

+ φ₂)_{? 3}~₂cos(27_ct + φ₃)？ 4 = a₄c s(27_ct +₄)，_lt>a₂,a₃₉a₄e [0，+oo)， ^₁₅^_2?^₃,^₄e [0,2π)。

In engineering practice, more variations of the address code are sometimes required. This requires equivalent transformations of the generated multi-address code, which are very diverse and cannot be listed as ^ a, and some of the most basic equivalent transformations are listed as follows:

the positions of the C and S codes are exchanged.

The positions of C1 and C2 and S1 and S2 were exchanged simultaneously.

And (5) inverting the code sequence.

The code bits are inverted.

Interleaving the polarity of each code bit: for example, (+ - +, + - - - -, + - +) may be staggered with respect to the polarity of each code bit, i.e., where the first, third, etc. odd code bits of each code are of constant polarity, while the second, fourth, etc. even code bits are of constant polarity, and (+ -, + - +), (+ -, + + + -), or odd code bits are of varying polarity, while even code bits are of constant polarity.

And (3) carrying out rotation change on each code bit in a complex plane: for example, the basic complementary code pairs may be sequentially rotated by one degree for each code bit of (++++, + -), + - ++)

Vq ψαχ +«) _ Ψα J(^_Cf+3α)_t_⁺⁰^ — +2") _ +3 )

t y ~ ti

(c'^-i⁺^j^c₂ ^+2ff) — ·/·(^₂+3α) )ψ — _/( .₂+α) _/(ρ,、.₂+2α) _/(^₂+3α)

fci ti fci ■ & -fci ί ί, and can be any initial angle, the properties of the autocorrelation function and the cross-correlation function of each address code after rotation transformation can be verified to be unchanged, but the secondary peak outside the zero correlation window is related to the rotation angle (becomes smaller or changes the polarity).

Different rotation angles are properly selected, so that the rotated code groups are orthogonal, namely, a group of orthogonal codes can generate a plurality of groups of orthogonal codes, and great convenience is brought to engineering application. Especially, when the code length is longer, wonderful results can be obtained sometimes, and various actual engineering requirements, such as networking requirements, switching requirements, even capacity increasing requirements and the like, can be met.

Changes are made in the spanning tree: for example, fig. 2 is an equivalent transformation of fig. 1, i.e., fig. 2 is a transformation in which C1 and S1 of all upper halves of fig. 1 are moved to the left, C2 and S2 are moved to the right, and C1 and S1 of all lower halves of fig. 1 are moved to the right, and C2 and S2 are moved to the left. For another example, the code bits of the C code and the S code in the generated multi-address code group may be staggered according to a certain rule, or arranged in a changed polarity. This transformation is called mathematically as an equivalent transformation, and there are many kinds of equivalent transformations, which are not listed here. The use of orthogonal complementary codes in engineering applications must ensure that the C code operates only with the C code (including self and other codes), the S code operates only with the S code (including self and other codes), and the C code and S code are absolutely impermissible. Therefore, special separation measures should be taken in practical application. For example, the C code and the S code can be modulated on the orthogonal polarized waves (horizontal and vertical polarized waves, left-handed and right-handed polarized waves) respectively, and for example, the C code and the S code can be placed in two time slots that are not overlapped after transmission. Since the transmission channel varies randomly with time, in order to ensure the implementation of complementarity, the channel characteristics in the two polarized waves and in the two time slots should be kept consistent during transmission. In the descriptive language of sentence change engineering, their fades should be synchronized. This requires that when polarization separation is used, a frequency band and corresponding measures must be used to ensure synchronous fading and no depolarization of orthogonal polarized waves, when time division separation is used, the interval between two time slots must be much shorter than the correlation time of the channel, and when other separation methods are used, their synchronous fading must also be ensured.

Since the C-code and S-code should be transmitted separately and at the same time take advantage of their complementarity, it is clear that the information bits modulated on them should be identical and the despread and demodulated outputs for the C-code and S-code should be compatible.

The invention provides a new coding method of space-time spread spectrum multi-address codes, which ensures that the formed correlation characteristics between groups of the space-time spread spectrum multi-address codes have a zero correlation window, namely, the correlation function and the cross-correlation function between the space-time address codes of each group in the zero correlation window have no peak, thereby eliminating the Multiple Access Interference (MAI) between the groups, and although the Multiple Access Interference (MAI) exists between the address codes in the same group, the optimal receiving can be achieved by utilizing the joint detection technology. The space-time spread spectrum code coding method with the inter-group zero correlation window characteristic provided by the invention combines the diversity technology and the zero correlation window characteristic, and can utilize the joint detection, the interference cancellation technology and the equalization technology, thereby providing possibility for increasing the system capacity. Meanwhile, the invention solves the complexity problem of applying combined detection in the traditional CDMA system. And joint detection, interference cancellation technology and equalization technology can be utilized, so that the possibility of increasing the system capacity is provided. Meanwhile, the invention solves the complexity problem of applying joint detection in the traditional CDM system.

Claims

Claims to follow

1. A space-time spread spectrum multiple address code coding method, characterized in that it comprises the following sub-steps: generating a basic orthogonal complementary code set with each code length being N and the width of a zero correlation window being L; expanding the generated basic orthogonal complementary code group pair to obtain a space-time positive interactive code group kernel with an inter-group zero correlation window;

and expanding the code length and the code number of the space-time orthogonal complementary code group core with the intergroup zero correlation window, wherein the cross-correlation function between the space-time address codes of each group obtained after expansion has the zero correlation window.
2. The method of claim 1, wherein the size of the interclass zero correlation window among the groups of space-time spreading address codes formed after spreading can be increased by inserting a zero guard interval or a time slot into the kernel of the space-time orthogonal complementary code with the interclass zero correlation window or each of the space-time spreading address codes after spreading.
3. The method of claim 1, wherein generating the set of substantially orthogonal complementary codes having each code length of N and zero and a correlation window width of L comprises: one or more pairs of basic orthogonal complementary code sets with the code length being N and the width of the zero correlation window being L can be selected; and:

can be provided with: (C S), (C) and (C),₂， S，₂) Is the basic orthogonal complementary code set, and has:
C₂₂"'C_2N)，

S'i~(S_uS₁₂"'S_1N)， S,₂=(S₂₁S₂₂,··8_2Ν)，

the non-periodic autocorrelation and cross-correlation functions of the c code and the s code are opposite in phase in a zero correlation window except the origin, and the added autocorrelation function value and cross-correlation function value are zero everywhere except the origin.
4. The method of claim 1, wherein said extending said set of substantially positive inter-complement groups comprises:

for a selected pair of substantially orthogonal complementary codes (C 'S', )、（C，₂， S'₂) Carrying out an expansion, wherein: c1- (C)_nC₁₂""C_1N)₉C 2~(_ltC₂₂*"C_2N)，

S'i~(Sn S_U'"S_1N)，
S₂₂'"S_2N);

The obtained space-time orthogonal complementary code group kernel with the inter-group zero correlation window is as follows:
5. the method of claim 4, wherein the space-time orthogonal complementary code-group kernel with the inter-group zero correlation window is: the length of each code of the space-time orthogonal complementary code group core formed after the expansion is 2N, and the width of the inter-group zero correlation window is more than or equal to 2L-1.
6. The method according to claim 2, wherein said processing of inserting zero guard interval or slot into said space-time orthogonal complementary code-group core with inter-group zero correlation window comprises:

the size of the intergroup zero correlation windows among the groups of space-time spread spectrum address codes formed after expansion can be increased by inserting zero guard intervals or time slots into the space-time orthogonal complementary code group cores with the intergroup zero correlation windows.
7. The method of claim 2, wherein the inserting of the zero guard interval or the time slot into the space-time orthogonal complementary code group core of the inter-group zero correlation window is: firstly, the basic orthogonal complementary code pair group (C ') with each code length of N and zero correlation window width of L is formed'_1?S'j), (C，₂, S，₂), ^Ί⁼(Cii C₁₂...C_1N) , C'₂= (C₂₁C₂₂".C_2N)， S'^ (S_nS₁₂...S_1N)， S，₂=(S₂₁S₂₂...S_2N) The code length is 2N, the width of the intergroup zero correlation window is 2L-1, and the code length is the following:

n S₁₂S₁₂...S_1NS_1N

S_nS₁₂-S₁₂...S_1N-S_1N

S₂₁S₂₂S₂₂...S₂N S_2N

" C₂i C₂₂- C₂₂· ' · C_2N- C_2NI -S₂₁S₂₂-S₂₂...S_2N-S_2Nthen, a certain number of zero guard intervals or time slots can be inserted into the space-time orthogonal complementary code group core, so that the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group core is larger than that of the original space-time orthogonal complementary code group core.
8. The method of claim 7, wherein the inserting of the zero guard interval or the time slot into the space-time orthogonal complementary code group kernel of the inter-group zero correlation window is: inserting T zeros every L +1 chips (Chip), wherein the inter-group zero correlation window width of a new space-time orthogonal complementary code group kernel formed by inserting T zeros is larger than or equal to 2L-1, the new space-time orthogonal complementary code group kernel continuously expands according to a tree structure, and the inter-group zero correlation window width of the obtained space-time orthogonal complementary code group pair is larger than or equal to 2L-1:

is s„ s 12 s,. s L+l .L+l 0...0 s

2 2

s, • s · · S L+l

1 - S L+l 0...0 s , ,L+1 ,、 - S L+l ,、 Sl_N" S_1N0...0

1

2 2
9. the method of claim 8, wherein (C) is true if the set of substantially orthogonal complementary code sets is (C, S), (C) is true₂， S₂) Each code length of N and the width of the zero correlation window of L, then T zeros may be inserted for every L +1 chips (chips) of the extended each code length of 2N space-time orthogonal complementary code group kernel; the width of the intergroup zero correlation window of the formed new space-time orthogonal complementary code group kernel is greater than or equal to 2L-1, the new space-time orthogonal complementary code group kernel is continuously expanded according to a spanning tree structure, and the width of the intergroup zero correlation window of the obtained space-time orthogonal complementary code group pair is greater than or equal to 2L-L
10. The method of claim 9, wherein said inserting T zeros satisfies the following condition: and maximizing the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group kernel.
11. The method of claim 9, wherein said inserting T zeros comprises: t zeros are inserted at the tail of every L +1 chips, T zeros are inserted at the head of every L +1 chips, etc.
12. The method according to claim 2, wherein said step of expanding each space-time spreading address code with intergroup zero correlation window by inserting a zero guard interval or time slot refers to: and inserting a certain number of zero guard intervals or time slots into each space-time spread spectrum address code which is generated by the core expansion of the space-time orthogonal complementary code group and has an intergroup zero correlation window, wherein the intergroup zero correlation window width of the formed new space-time orthogonal complementary code group is larger than or equal to the intergroup zero correlation window width of the original space-time orthogonal complementary code group.
13. The method according to claim 12, wherein if said extended groups of space-time spreading address codes have zero correlation windows with inter-group widths of 2W "1, T zeros can be inserted for every W chips of the extended groups of space-time spreading address codes; the width of the intergroup zero correlation window of the formed new space-time orthogonal complementary code group is larger than or equal to 2W-1.
14. The method of claim 13, wherein said inserting T zeros satisfies the following condition: the inter-group zero correlation window width of the formed new space-time orthogonal complementary code set is maximized.
15. The method of claim 13, wherein said inserting T zeros comprises: t zeros are inserted at the tail of every L +1 chips, T zeros are inserted at the head of every L +1 chips, etc.
16. The method according to claim 1, 3 or 4, wherein the space-time spreading address code is operated by: the C code is only operated with the C code and contains self code and other codes; the S code operates only with the S code, including itself and other codes.
17. The method of claim 3 or 4, wherein the set of substantially orthogonal complementary code pairs (C) is selected from the group consisting of₂, S₂) The method comprises the following steps: the autocorrelation and cross-correlation functions are the sum of the aperiodic autocorrelation and cross-correlation functions between C codes and S codes respectively, wherein the sum is within a zero correlation windowThe non-periodic autocorrelation and cross-correlation functions of the C code and the S code are formed in a reverse phase manner except for the origin, and the added autocorrelation function value and cross-correlation function value are zero everywhere except for the origin.
18. The method of claim 1, wherein spreading the length and number of the omitted space-time orthogonal complementary code-group kernels with inter-group zero correlation windows comprises:

according to the actually needed maximum user address number, the positive interactive code complementing group core is expanded in code length and code number in a spanning tree structure, a target window exists near the cross-correlation point among the expanded groups of space-time spread spectrum address codes, and the window value t is ^ 2L-1; the autocorrelation function of each expanded space-time spread spectrum address code is not zero only at two non-zero relative time delays except the origin in the intergroup zero correlation window, and is zero at other positions; the cross-correlation function of each space-time spread spectrum address code in the same group is not zero only at two non-zero relative time delays and is zero at other positions in the above-mentioned intergroup zero correlation window.

The method of claim 18, wherein the spreading the code length and the number of codes of the space-time orthogonal complementary code group kernel in the spanning tree structure is:

if (C)₁S, ), ( C₂, S₂) If a pair of space-time orthogonal complementary code groups with each code length N and a zero correlation window width L is used, two pairs, namely four pairs of space-time orthogonal complementary code groups with each code length 2N, can be generated in the following manner:

(C, C₂， S, S₂)

(C₂-C，， S₂-S,) wherein, spreading

The correlation function has a zero correlation window near the origin, the window width is larger than or equal to L, the orthogonal complementary code group kernel with 2N and the width larger than or equal to L of the zero correlation window continues to expand to obtain four pairs of space-time orthogonal complementary code group pairs, the interclass cross correlation function has a zero correlation window near the origin, the window width is larger than or equal to ^
20. The method of claim 12, wherein the expanding is continued in a spanning tree structure to produce a code length of N2ⁿInter-group zero correlation window width greater than or equal to 2 of LⁿThe number of spreading times is n =0, 1, 2, … in each space-time orthogonal complementary code pair.
21. A space-time spread spectrum multiple address code application method is characterized by comprising the following steps: determining the width of a required zero correlation window according to the propagation condition of an applied system, the basic spread spectrum code rate adopted by the system and the maximum timing error in the system;

generating a basic orthogonal complementary code pair according to the width of a required zero correlation window;

expanding the basic orthogonal complementary code group pair to generate a space-time orthogonal mutual-interference code group kernel with an inter-group zero correlation window;

determining the required maximum user address number according to the number of actual users, taking a selected space-time orthogonal complementary code group core with an inter-group zero correlation window as an original point, expanding the code length and the code number in a spanning tree structure, and enabling a cross correlation function among the expanded groups of space-time spread spectrum address codes to have an inter-group zero correlation window near the original point;

and respectively carrying out spread spectrum modulation transmission on each group of the expanded space-time spread spectrum address codes with the intergroup zero correlation windows on corresponding transmitters.
22. The method of claim 21, wherein generating the pair of substantially orthogonal complementary codes comprises: the length of each code is N,The zero correlation window has a width L of the basic orthogonal complementary code pair (d, (C)₂， S₂) Said (d, S and (C)₂， S₂) The autocorrelation and cross-correlation functions of the code C and the code S are respectively the sum of the aperiodic autocorrelation and cross-correlation functions between the code C and the code S and the aperiodic autocorrelation and cross-correlation functions between the code S and the code C, wherein in a zero correlation window with the width of L, the aperiodic autocorrelation and cross-correlation functions of the code C and the code S are opposite to each other except the origin, and the added autocorrelation function values and cross-correlation function values are zero everywhere except the origin.
23. The method of claim 22, wherein the generating or selecting the set of substantially orthogonal complementary code pairs comprises: the basic orthogonal complementary code pair (C Sj) (C)₂, S₂) May be generated using a spanning tree structure.
24. The method of claim 21, wherein the expanding the set of substantially orthogonal complementary code groups to generate a space-time orthogonal complementary code group kernel with an inter-group zero correlation window comprises:

for the obtained basic orthogonal complementary code pair with each code length of N and zero correlation window width of L (,_Sl)、（c₂， s₂) And expanding the space-time orthogonal complementary code group kernel into a space-time orthogonal complementary code group kernel with an inter-group zero correlation window in the following way, wherein: c! C "C₁₂'"C_1N)，
s₂₂

^2 )；

n S₁₂S₁₂...S_1NS_1N、

S_uS₁₂- S₁₂...S_1N- S_mS₂₁S₂₂S₂₂- -S_2NS_2N、

"" S₂₁S₂₂- S₂₂...S_2N- S_2NThe length of each code of the expanded space-time orthogonal complementary code group core is 2N, and the width of the inter-group zero correlation window is more than or equal to 2L-1.
25. The method of claim 24, wherein a number of zero guard intervals or slots are inserted into the space-time positive complementary code group kernel, such that an inter-group zero correlation window width of a new space-time positive complementary code group kernel is formed to be larger than that of an original space-time orthogonal complementary code group kernel.
26. The method of claim 25, wherein (C) is selected if the pair of substantially orthogonal complementary codes (C S), (C) is selected₂， S₂) Each code length of N and the width of the zero correlation window of L, then every L +1 chips of the space-time orthogonal complementary code group kernel with each code length of 2N after the spreading can be used

(Chip) inserting T zeros; t zeros can be inserted into the tail of every L +1 chips (Chip), the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group core is greater than or equal to 2L-1, the new space-time orthogonal complementary code group core is continuously expanded according to a spanning tree structure, and the inter-group zero correlation window width of the obtained space-time orthogonal complementary code group pair is greater than or equal to 2L-1.
27. The method of claim 26, wherein said inserting T zeros satisfies the following condition: and maximizing the inter-group zero correlation window width of the formed new space-time orthogonal complementary code group kernel.
28. The method of claim 26, wherein said inserting T zeros comprises: t zeros are inserted at the tail of every L +1 chips (Chip), T zeros are inserted at the head of every L +1 chips (Chip), and so on.
29. The method of claim 21 wherein the extension is determined by the number of extension stages required in the spanning tree based on the maximum number of users required and the number of groups selected from the set of substantially orthogonal complementary code pairs.
30. The method of claim 21, wherein spreading the extended groups of space-time spreading address codes with inter-group zero correlation windows on corresponding transmitters respectively for modulation transmission comprises: spread spectrum modulation transmission can be respectively carried out on the corresponding two transmitters for each of the space-time spread spectrum address codes with the intergroup zero correlation windows; and the two same transmitters can be corresponded to the group and the group.
31. The method of claim 21, wherein the spreading modulation transmitting the extended groups of space-time spreading address codes with inter-group zero correlation windows on corresponding transmitters respectively comprises: for each group of space-time spread spectrum address codes with the inter-group zero correlation window, the space-time spread spectrum address codes can be respectively spread spectrum modulated and transmitted on the corresponding two transmitters; and two different transmitters can be respectively corresponding to the groups.
32. The method of claim 21, wherein the spreading modulation transmitting the extended groups of space-time spreading address codes with inter-group zero correlation windows on corresponding transmitters respectively comprises: when the following two sets of space-time orthogonal complementary code sets are employed:

transmitting each code of the two groups of space-time orthogonal complementary code groups on two transmitters, wherein the groups can correspond to the same two transmitters or respectively correspond to two different groups of two transmitters;

the correspondence between two space-time orthogonal complementary codes in the same group and two transmitters is as follows: for a first space-time orthogonal complementary code, transmitting all odd chips (chips) corresponding to corresponding odd chips at a first transmitter and transmitting all even chips (chips) corresponding to corresponding even chips at a second transmitter; for all odd chips (chips) of the second space-time orthogonal complementary code corresponding to the corresponding odd chips transmitted at the second transmitter, and all even chips (chips) corresponding to the corresponding even chips transmitted at the first transmitter; or vice versa, i.e. for the second space-time orthogonal complementary code, all odd chips (chips) correspond to the corresponding odd Chip transmissions at the first transmitter, and all even chips (chips) correspond to the corresponding even Chip transmissions at the second transmitter; all odd chips (chips) for the first space-time orthogonal complementary code correspond to corresponding odd Chip transmissions at the second transmitter and all even chips (chips) correspond to corresponding even Chip transmissions at the first transmitter.
33. The method of claim 26, wherein the space-time orthogonality refers to: when each space-time spread spectrum address code of the two groups of space-time orthogonal complementary code groups is transmitted on two transmitters to form two groups of four space-time sequences, the two groups of space-time sequences keep orthogonal between groups and have zero correlation windows between the groups,

-S_naj S_{12 2}-S_l2ci₁,..S_{iN 2}-S_1Nj/

/

wherein:

a_{= a cos(2¾Tt + φ_λ), a₂= a₂cos(2^T_ct + ^?₂) , a₃=₃cos(2 t + φ_ζ) , a₄=a₄cos(2¾f"_ct + ^₄) , ,α₂,α₃,₄e [0,+oo), φ₁,φ₂,φ₃, φ e[0,2;r)。
34. a method as claimed in claim 1 or 21, characterized in that the generated multi-address code is equivalently transformed.
35. The method of claim 34, wherein said equivalent transformation comprises:

swapping the positions of C and S codes, swapping the positions of C1 and C2 and S1 and S2 simultaneously, inverting the code order, inverting each code bit, interleaving the polarity of each code bit, rotating each code bit in the complex plane, changing in the spanning tree, and the like.
36. The method of claim 35 wherein said rotationally varying each code bit in the complex plane comprises:

the basic complementary code group can be rotated to each code bit by 'degree' in sequence, the properties of the autocorrelation function and the cross-correlation function of each address code after rotation transformation are unchanged, but a 'zero correlation window', and the external secondary peak is related to the rotation angle; by properly selecting the rotation angle, the rotated code groups can be orthogonal, and a plurality of groups of orthogonal codes can be generated by one group of orthogonal codes.
37. The method of claim 36, wherein the generated sets of orthogonal codes are adapted for networking requirements, handover requirements, capacity increase requirements, etc.; especially when the code length is long.
38. The method of claim 1, 15 or 16 wherein the positive complementary codes ensure that the C code operates only with the C code (including self and other codes) and the S code operates only with the S code (including self and other codes).
39. The method of claim 38, wherein a separation measure is applied to the C code and the S code in practical application.
40. The method of claim 39, wherein said separating means comprises: respectively modulating the C code and the S code on mutually orthogonal polarized waves; or the C code and the S code can be respectively placed in two time slots which are still not overlapped after transmission.
41. The method of claim 40, wherein the transmission channel varies randomly over time, and to ensure complementarity, the channel characteristics in both polarized waves and in both time slots should be kept consistent during transmission, i.e.: their fades should be synchronized; this requires that when polarization separation is used, a frequency band and corresponding measures must be used to ensure synchronous fading of orthogonal polarization waves without depolarization, when time division separation is used, the interval between two time slots must be much shorter than the correlation time of the channel, and when other separation methods are used, synchronous fading of the two time slots must also be ensured.
42. The method of claim 41, wherein: since the C and S codes should be transmitted separately while taking advantage of their complementarity, the information bits modulated onto them should be the same, and the despread and demodulated outputs for the C and S codes should be summed.