CN108092692B - CDMA system channel spread spectrum device and method - Google Patents

CDMA system channel spread spectrum device and method Download PDF

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CN108092692B
CN108092692B CN201711448149.6A CN201711448149A CN108092692B CN 108092692 B CN108092692 B CN 108092692B CN 201711448149 A CN201711448149 A CN 201711448149A CN 108092692 B CN108092692 B CN 108092692B
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orthogonal
sequences
orthogonal sequence
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subsequence
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张卫国
闫家伟
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Xi'an Zhenrandong Technology Co.,Ltd.
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Xian Cresun Innovation Technology Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/004—Orthogonal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
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Abstract

The invention discloses a CDMA system channel spread spectrum device, which is characterized in that the device comprises: an orthogonal sequence generation module for generating an orthogonal sequence set; a storage module, connected to the orthogonal sequence generation module, for storing the orthogonal sequence set; the control module is connected with the storage module and used for reading the available orthogonal sequences in the orthogonal sequence set when a user request control signal is received; and the channel machine is connected with the control module and used for receiving the user request data, and outputting the user request data after spreading the frequency according to the available orthogonal sequence. The CDMA system channel spread spectrum device of the invention obtains a corresponding orthogonal sequence set by selecting specific input and output and utilizing the semi-bent function construction so as to improve the number of sequences allocated by a cell and solve the problem that the communication cannot be normally carried out due to excessive users.

Description

CDMA system channel spread spectrum device and method
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to a CDMA system channel spread spectrum device and a method.
Background
The design of a CDMA (Code Division Multiple Access) system is generally based on a length of 2mThe use of (binary) orthogonal sequences (codewords). Even if the whole space has 22mIndividual code words, but it is difficult to find large subsets of radix sequences that are orthogonal to each other within a class. These subsets of sequences are randomly assigned to users of the cell, where each user is assigned a unique sequence from this subset. As a regular hexagonal cell grid, a standard requirement is that the sequences in any cell must be orthogonal to the sequences in neighboring cells in order to prevent interference from neighboring cells. In addition, the correlation value of any given cell with the sequences in non-adjacent cellsShould be sufficiently small and in the interval [2 ]m/2,2(m+2)/2]And (4) the following steps. One of the most common methods of constructing spreading code sequences in these systems is to use a set of correlation value limited Hadamard matrices (Hadamard matrices).
In one construction of the prior art, referring to W. -G.Zhang, C. -L.Xie, and E.Pasalic, "Large Sets of Orthogonal Sequences sufficient for Applications in CDMASystems," IEEE Transactions on Information Theory, vol.62, No.6, pp.3757-3767, June 2016, the method generates a Large set of Sequences (within each set) that are Orthogonal to each other, with the vast majority of the Sets of Sequences also being Orthogonal to each other, covering firstly the parity of m, and secondly the difficult combination problem of assigning Orthogonal Sets of Sequences to the same cell and ensuring orthogonality of neighboring cells, which is achieved with a number of users per cell of 2m-2However, the prior art construction method has a small number of sequences allocated to cells, and the interference between cells is strong, which cannot satisfy normal communication of a larger number of users.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a CDMA system channel spreading device and method with high interference rejection capability and capable of increasing user capacity.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that:
a channel spreading device for a CDMA system, comprising:
an orthogonal sequence generation module for generating an orthogonal sequence set;
a storage module, connected to the orthogonal sequence generation module, for storing the orthogonal sequence set;
the control module is connected with the storage module and used for reading the available orthogonal sequences in the orthogonal sequence set when a user request control signal is received;
and the channel machine is connected with the control module and used for receiving the user request data, and outputting the user request data after spreading the frequency according to the available orthogonal sequence.
In a specific embodiment, the orthogonal sequence generation module includes a vector semi-bent generation unit, an orthogonal sequence set construction unit, and an orthogonal sequence set allocation unit;
the vector semi-bent generating unit is used for selecting a vector semi-bent function with m input and k output;
the orthogonal sequence set constructing unit is used for constructing 3 x 2 by utilizing the vector semi-bent functionkA set of orthogonal sequences such that there is 2 in the set of orthogonal sequenceskThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of;
the orthogonal sequence set allocation unit is used for arranging the cells according to a preset rule by the orthogonal sequence set, so that the sequences in the cells are mutually orthogonal, and the sequence sets of adjacent cells are mutually orthogonal;
wherein m and k are positive integers, and m is 2k + 2.
In a specific embodiment, the orthogonal multiplexing distance of the adjacent cells is
Figure GDA0002100357390000031
In a specific embodiment, the orthogonal sequence set constructing unit further includes a semi-bent function generating subunit, a hadamard matrix generating subunit, and an orthogonal sequence set generating subunit;
the semi-bent function generating subunit is used for obtaining 2 according to the vector semi-bent functionkA semi-bent function;
the Hadamard matrix generation subunit is used for selecting 2m×2mA dimension Hadamard matrix, and dividing the Hadamard matrix into a first subsequence set, a second subsequence set and a third subsequence set, wherein the sequence number of the first subsequence set is 2m-1The number of sequences in the second subsequence set and the third subsequence set is 2m-2A plurality of;
the orthogonal sequence set generation subunit is configured to generate the 2kMultiplying the corresponding bit of each semi-bent function with the corresponding bit of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2kA first set of orthogonal sequences, 2kA second set of orthogonal sequences, 2kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2m-2And (4) respectively.
The embodiment of the invention also provides a CDMA system channel spreading method, which comprises the following steps:
s1, generating an orthogonal sequence set;
s2, storing the orthogonal sequence set;
s3, when a user request control signal is received, reading available orthogonal sequences in the orthogonal sequence set;
and S4, receiving user request data, and outputting the user request data after spreading according to the available orthogonal sequence.
In a specific embodiment, the step S1 further includes:
s11, selecting a vector semi-bent function of m input and k output, wherein m and k are positive integers, and m is 2k + 2;
s12, constructing 3 x 2 by using the vector semi-bent functionkA set of orthogonal sequences, wherein there are 2 in the set of orthogonal sequenceskThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of;
and S13, arranging the cells according to the orthogonal sequence set according to a preset rule, so that the sequences in the cells are mutually orthogonal, and the sequence sets of the adjacent cells are mutually orthogonal.
In a specific embodiment, the step S12 further includes:
s121, obtaining 2 according to the vector semi-bent functionkA semi-bent function;
s122, selection 2m×2mA dimensional Hadamard matrix, and dividing the Hadamard matrix into a first subsequence set, a second subsequence set, and a third subsequenceSet, wherein the sequence number of the first subsequence set is 2m-1The number of sequences in the second subsequence set and the third subsequence set is 2m-2A plurality of;
s123, mixing the 2kMultiplying the corresponding bit of each semi-bent function with the corresponding bit of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2kA first set of orthogonal sequences, 2kA second set of orthogonal sequences, 2kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2m-2And (4) respectively.
In a specific embodiment, the orthogonal multiplexing distance of the adjacent cells is
The CDMA system channel spread spectrum device of the invention obtains a corresponding orthogonal sequence set by selecting specific input and output and utilizing the semi-bent function construction so as to improve the number of sequences allocated by a cell and solve the problem that the communication cannot be normally carried out due to excessive users.
Drawings
Fig. 1 is a block diagram of a channel spreading device of a CDMA system according to an embodiment of the present invention;
fig. 2 is a block diagram of an orthogonal sequence generating module of a channel spreading device of a CDMA system according to an embodiment of the present invention;
fig. 3 is a flowchart of a channel spreading method of a CDMA system according to an embodiment of the present invention;
fig. 4 is a flowchart of a method for generating an orthogonal sequence set according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a regular hexagonal network allocation in an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.
Example one
Referring to fig. 1, fig. 1 is a block diagram of a CDMA system channel spreading device according to an embodiment of the present invention, including:
an orthogonal sequence generation module 1, for generating an orthogonal sequence set;
a storage module 2 connected to the orthogonal sequence generation module for storing the orthogonal sequence set;
the control module 3 is connected with the storage module and used for reading the available orthogonal sequences in the orthogonal sequence set when receiving a user request control signal;
and the channel machine 4 is connected with the control module and used for receiving the user request data, and outputting the user request data after spreading the frequency according to the available orthogonal sequence.
In an embodiment, please refer to fig. 2, fig. 2 is a block diagram of an orthogonal sequence generating module of a CDMA system channel spreading device according to an embodiment of the present invention, where the orthogonal sequence generating module 1 includes a vector semi-bent generating unit 11, an orthogonal sequence set constructing unit 12, and an orthogonal sequence set allocating unit 13;
the vector semi-bent generating unit 11 is configured to select a vector semi-bent function with m inputs and k outputs;
the orthogonal sequence set constructing unit 12 is configured to construct 3 × 2 by using the vector semi-bent functionkA set of orthogonal sequences such that there is 2 in the set of orthogonal sequenceskThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of;
the orthogonal sequence set allocation unit 13 is configured to arrange the cells according to a predetermined rule by using the orthogonal sequence set, so that the sequences in the cells are orthogonal to each other, and the sequence sets of adjacent cells are orthogonal to each other;
wherein m and k are positive integers, and m is 2k + 2.
In a specific embodiment, the orthogonal multiplexing distance of the adjacent cells is
Figure GDA0002100357390000061
In a specific embodiment, the orthogonal sequence set constructing unit further includes a semi-bent function generating subunit, a hadamard matrix generating subunit, and an orthogonal sequence set generating subunit;
the semi-bent function generating subunit is used for obtaining 2 according to the vector semi-bent functionkA semi-bent function;
the Hadamard matrix generation subunit is used for selecting 2m×2mA dimension Hadamard matrix, and dividing the Hadamard matrix into a first subsequence set, a second subsequence set and a third subsequence set, wherein the sequence number of the first subsequence set is 2m-1The number of sequences in the second subsequence set and the third subsequence set is 2m-2A plurality of;
the orthogonal sequence set generation subunit is configured to generate the 2kMultiplying the corresponding bit of each semi-bent function with the corresponding bit of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2kA first set of orthogonal sequences, 2kA second set of orthogonal sequences, 2kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2m-2And (4) respectively.
The CDMA system channel spread spectrum device of the invention obtains a corresponding orthogonal sequence set by selecting specific input and output and utilizing the semi-bent function construction so as to improve the number of sequences allocated by a cell and solve the problem that the communication cannot be normally carried out due to excessive users.
Example two
Referring to fig. 3, fig. 3 is a flowchart of a channel spreading method of a CDMA system according to an embodiment of the present invention, including:
s1, generating an orthogonal sequence set;
s2, storing the orthogonal sequence set;
s3, when a user request control signal is received, reading available orthogonal sequences in the orthogonal sequence set;
and S4, receiving user request data, and outputting the user request data after spreading according to the available orthogonal sequence.
To better illustrate the method provided by the present invention, the technical background of the present invention is first described as follows. First we introduce some concepts and tools related to boolean functions and sequences.
Is provided withIs a vector space of dimension m and is,
Figure GDA0002100357390000072
is a finite field over GF (2), then the m-ary Boolean function f (x) is expressed as a certain valueTo
Figure GDA0002100357390000074
Is here mapped to
Figure GDA0002100357390000075
Let BmRepresenting the set of all m-ary boolean functions. The invention uses "+" and ∑ valuesiTo replace
Figure GDA0002100357390000076
And
Figure GDA0002100357390000077
the addition operation in (1). Any Boolean function f ∈ BmCan be represented by its algebraic formal:
Figure GDA0002100357390000078
wherein
Figure GDA0002100357390000079
The algebraic degree of f (x) is such thatbWt: (not equal to 0)b) Is given as deg (f), wherein wt (b) is the Hamming weight of b. When deg (f) is 1, f is called an affine function.
For theThe inner product of a and b is defined as:
Figure GDA00021003573900000711
where the addition is a modulo-2 operation.
At will
Figure GDA0002100357390000081
The linear function above can be defined by the inner product ω · x. Wherein
Figure GDA0002100357390000082
And each omega distinguishes a different linear function. The set containing all m linear functions is defined as
Figure GDA0002100357390000083
Thus, it is possible to provide
Figure GDA0002100357390000084
Let BmRepresents the set of all m-ary Boolean functions, for an arbitrary f ∈ BmThe Walsh spectrum is defined as follows:
Figure GDA0002100357390000085
definition of
Figure GDA0002100357390000086
The support set is a function f. If an m-ary function f ∈ BmThe truth table of (2) is called a balance function if the numbers of 0 and 1 are equal, i.e., # supp (f) ═ 2m-1Or is:
Wf(0m)＝0(4)
wherein 0mThe m long 0 vectors are shown.
Function f ∈ BmIs a sequence of length N-2mThe (1, -1) sequence of (a), defined as:
Figure GDA0002100357390000087
vector quantity
Figure GDA0002100357390000088
Andexpressed as
Figure GDA00021003573900000810
Is defined as:
Figure GDA00021003573900000811
thus it can be derived
Figure GDA00021003573900000812
Where l ═ ω · x.
A 2m×2mOf the Hadamard matrix
Figure GDA00021003573900000813
Is defined as:
Figure GDA00021003573900000814
let r bej,0≤j≤2m-1 is
Figure GDA00021003573900000815
Column j of (1), then rjIs a linear sequence, i.e. a set
H＝{rj|0≤j≤2m-1} (8)
Is a set of Hadamard sequences of sequence numbers,
Figure GDA0002100357390000091
according to the above scheme, the present invention provides the following definitions:
definition 1: let f1,f2∈Bm. If so:
Figure GDA0002100357390000092
namely, it is
Figure GDA0002100357390000093
And
Figure GDA0002100357390000094
is orthogonal withAnd (4) showing. Order to
Figure GDA0002100357390000096
If set S
Figure GDA0002100357390000097
And if the two pairs are orthogonal, S is an orthogonal sequence set with the base of k. Order S1，S2Is a set of orthogonal sequences, for arbitraryAlways have
Figure GDA0002100357390000099
Then call S1,S2Is orthogonal, with S1⊥S2And (4) showing.
The invention derives the following properties of orthogonal sequences:
introduction 1: let f1,f2∈Bm. Then
Figure GDA00021003573900000910
If and only if
Figure GDA00021003573900000911
For any two different linear functions
Figure GDA00021003573900000912
Wl+l′(0m) 0, then
Figure GDA00021003573900000913
The overall result is that H is a set of orthogonal sequences.
Definition 2: if for any
Figure GDA00021003573900000914
Wf(α)∈{0,±2λWhere λ ≧ m/2 is a positive integer, this function f is called the Plateaued function. When in use
Figure GDA00021003573900000915
This function is called the semi-bent function. If f is a Plateaued function (semi-bent function), then f is called a Plateated sequence (semi-bent sequence).
The Maiorana-McFarland class function is defined as follows.
Definition 3: for any positive integer, m ═ s + t, a Maiorana-McFarland function is defined as:
Figure GDA00021003573900000916
wherein phi is
Figure GDA00021003573900000917
To
Figure GDA00021003573900000918
And g e Bs。
When s ≦ t and φ is set alone, then the Maiorana-McFarland class function is a Plateaued function. In particular, when s is t and φ is bijective, we get the Maiorana-McFarland class of the best function.
Definition 4: an m-argument t-dimensional vector function is a mapping function
Figure GDA0002100357390000101
The t-ary Boolean function set F (x) ═ f can also be considered1,...,ft). If component function f1,...,ftIs a spectral value taken from {0, + -2 }λThe ternary planeaued boolean function of F is then called a vector planeaued function. When in use
Figure GDA0002100357390000102
F is called the vector semi-bent function. If component function f1,...,ftIs a spectral value taken from { + -2m/2A binary bent function, then called F a vector bent function, where m is an even number and t ≦ m/2.
Based on the above definitions of the present invention, please continue to refer to fig. 4, where fig. 4 is a flowchart of a method for generating an orthogonal sequence set according to an embodiment of the present invention, including:
s11, selecting a vector semi-bent function of m input and k output, wherein m and k are positive integers, and m is 2k + 2;
s12, constructing 3 x 2 by using the vector semi-bent functionkA set of orthogonal sequences, wherein there are 2 in the set of orthogonal sequenceskThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of;
and S13, arranging the cells according to the orthogonal sequence set according to a preset rule, so that the sequences in the cells are mutually orthogonal, and the sequence sets of the adjacent cells are mutually orthogonal.
In one embodiment, the S12 includes,
s121, obtaining 2 according to the vector semi-bent functionkA semi-bent function;
specifically, in order to increase the number of users in a cell, m and k are two positive integers, andm is 2k +2, k is more than or equal to 2. Let gamma be
Figure GDA0002100357390000103
And {1, γ, …, γ)k-1Is as
Figure GDA0002100357390000104
On the upper partA set of polynomial bases. Defining isomorphic mappings
π(b1+b2γ+…+bkγk-1)＝(b1,b2,…,bk) (13)
Let bijective for i 1, …, kIs defined as:
Figure GDA0002100357390000112
wherein [ y ] is defined as an integer representation of y.
Order to
Figure GDA0002100357390000113
For i-1, …, k, a series of boolean functions are defined
Figure GDA0002100357390000114
fi(y,x,z)＝φi(y)·x (15)
Boolean function of vector
Figure GDA0002100357390000115
Is defined as:
F(x)＝(f1,…,fk) (16)
s122, selection 2m×2mUyghura japonicaA matrix of Hadamard, and dividing the Hadamard matrix into a first set of sub-sequences, a second set of sub-sequences and a third set of sub-sequences, wherein the number of sequences in the first set of sub-sequences is 2m-1The number of sequences in the second subsequence set and the third subsequence set is 2m-2A plurality of;
in particular, for any
Figure GDA0002100357390000116
Order to
fc(y,x,z)＝c·F(y,x,z)＝c1f1+...+ckfk(17)
For arbitrary fixation
Figure GDA0002100357390000117
Defining:
Figure GDA0002100357390000118
let T0＝L00∪L11，T1＝L01And T2＝L10。
S123, mixing the 2kMultiplying the corresponding bit of each semi-bent function with the corresponding bit of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2kA first set of orthogonal sequences, 2kA second set of orthogonal sequences, 2kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2m-2And (4) respectively.
Specifically, the structure 3.2kThe disjoint sequence sets are as follows:
Figure GDA0002100357390000119
wherein S isc,0The sequence has 2m-1One user, the other sequence has 2m-2And (4) users.
The CDMA system channel spread spectrum method of the invention obtains the corresponding orthogonal sequence set by selecting specific input and output and utilizing the semi-bent function construction so as to improve the number of sequences allocated by a cell and solve the problem that the communication cannot be normally carried out due to too many users.
In order to more clearly explain the construction process of the present invention, the present invention gives the following proving process.
Let m be 2k +2 for any
Figure GDA0002100357390000121
Order sequence set Sc,iAs defined in equation (19), then, there is:
i) for any one
Figure GDA0002100357390000122
Has | Sc,0|＝2m-1，|Sc,1|＝|Sc,2|＝2m-2。
ii) for any
Figure GDA0002100357390000123
i∈{0,1,2}，Sc,iIs an orthogonal semi-bent sequence set.
iii) for any
Figure GDA0002100357390000124
i,i′∈{0,1,2}，Sc,i⊥Sc′,i′If and only if i ≠ i'.
First, note | Lδ|＝22k＝2m-2This indicates that i) is true.
Secondly, for ii), for any
Figure GDA0002100357390000125
And is
Figure GDA0002100357390000126
Is provided with
Figure GDA0002100357390000127
Wherein
Figure GDA0002100357390000128
Due to the fact that
And
Figure GDA00021003573900001210
wherein for
Figure GDA00021003573900001211
When it is established, when γ is
Figure GDA00021003573900001212
When the primitive element is present, only one i is more than or equal to 0c≤2k-2, such that
Figure GDA00021003573900001213
Can know phic(y) is
Figure GDA00021003573900001214
One permutation of (a). There is therefore a single
Figure GDA00021003573900001215
So that phi isc(y) α, which indicates for any
Figure GDA0002100357390000131
Is provided with
Figure GDA0002100357390000132
For arbitraryIs provided with
Figure GDA0002100357390000134
In addition to this, the present invention is,
Figure GDA0002100357390000135
for arbitrary
Figure GDA0002100357390000136
Is provided with
Figure GDA0002100357390000137
When k is (m-2)/2, F is a vector semi-bent function.
Again, for iii), let
Figure GDA0002100357390000138
Where l ∈ Ti，l′∈Ti′。
To analyzeAnd
Figure GDA00021003573900001310
in consideration of orthogonality therebetween
h＝(fc+l)+(fc′+l′)＝fc+c′+(l+l′) (27)
Wherein
Figure GDA00021003573900001311
Because of the fact that
Figure GDA00021003573900001312
So equation fc+fc′＝fc+c′Can be easily obtained from the formula (21).
By equation (26), Wh(0m) 0 if and only if
Figure GDA00021003573900001315
As can be seen from table 1, it is,
Figure GDA00021003573900001313
if and only if i ≠ i'. This means Sc,i⊥Sc′,i′If and only if i ≠ i'.
Table 1: t isiOperation of
Figure GDA0002100357390000142
EXAMPLE III
The following example gives the orthogonal sequence S when m is 8c,iDistribution of (S)c,0Equivalent to a cell with a greater number of users 2m-1。
When m is 8, k is 3, which can be found from example two to yield 3 × 2324 disjoint orthogonal semi-bent sequences,
Figure GDA0002100357390000143
Sc,0the sequence has 2m-1Referring to fig. 5, fig. 5 is a schematic diagram of a regular hexagonal network allocation according to an embodiment of the present invention, and according to the distribution shown in fig. 5, the reusable distance is as followsWherein, the larger font is marked with 2m-1The cell of an individual user. Note that each cell is surrounded by 6 small cells, and each small cellThe cells are surrounded by 3 large cells and 3 small cells. In addition, two adjacent 2 s are viewed from a certain columnm-1The cells of each user are separated by two 2m-2The cell of a subscriber, which means that one third of the cells in the network has 2m-1A large cell of individual users. Referring to FIG. 5, for example, S000,0S in the same column001,0Is spaced by s000,1And s000,2Two cells.
The CDMA system channel spread spectrum device of the invention obtains a corresponding orthogonal sequence set by selecting specific input and output and utilizing the semi-bent function construction so as to improve the number of sequences allocated by a cell and solve the problem that the communication cannot be normally carried out due to excessive users.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (6)

1. A channel spreading device for a CDMA system, comprising:
orthogonal sequence generation module for generating 3 x 2kA set of orthogonal sequences, said 3 × 2kA set of orthogonal sequences, there is 2kThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of; after the cells are arranged in the orthogonal sequence set, the orthogonal multiplexing distance of the adjacent cells is as followsWherein m and k are both positive integers, and m is 2k + 2;
a storage module, connected to the orthogonal sequence generation module, for storing the orthogonal sequence set;
the control module is connected with the storage module and used for reading the available orthogonal sequences in the orthogonal sequence set when a user request control signal is received;
and the channel machine is connected with the control module and used for receiving the user request data, and outputting the user request data after spreading the frequency according to the available orthogonal sequence.
2. The CDMA system channel spreading device of claim 1, wherein the orthogonal sequence generating module comprises a vector semi-bent generating unit, an orthogonal sequence set constructing unit, and an orthogonal sequence set allocating unit;
the vector semi-bent generating unit is used for selecting a vector semi-bent function with m input and k output;
the orthogonal sequence set constructing unit is used for constructing 3 x 2 by utilizing the vector semi-bent functionkA set of orthogonal sequences such that there is 2 in the set of orthogonal sequenceskThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of;
the orthogonal sequence set allocation unit is used for arranging the cells according to a preset rule by the orthogonal sequence set, so that the sequences in the cells are mutually orthogonal, and the sequence sets of adjacent cells are mutually orthogonal.
3. The CDMA system channel spreading device of claim 2, wherein the orthogonal sequence set constructing unit further comprises a semi-bent function generating subunit, a hadamard matrix generating subunit, and an orthogonal sequence set generating subunit;
the semi-bent function generating subunit is used for obtaining 2 according to the vector semi-bent functionkA semi-bent function;
the Hadamard matrix generation subunit is used for selecting 2m×2mA Hadamard matrix is maintained, and the Hadamard matrix is divided into a first subsequence set, a second subsequence set and a third subsequence set, wherein the sequences of the first subsequence setThe number is 2m-1The number of sequences in the second subsequence set and the third subsequence set is 2m-2A plurality of;
the orthogonal sequence set generation subunit is configured to generate the 2kMultiplying the corresponding bit of each semi-bent function with the corresponding bit of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2kA first set of orthogonal sequences, 2kA second set of orthogonal sequences, 2kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2m-2And (4) respectively.
4. A method for spreading a channel in a CDMA system, comprising:
s1, generating 3X 2kA set of orthogonal sequences; the 3 x 2kA set of orthogonal sequences, there is 2kThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of; after the cells are arranged in the orthogonal sequence set, the orthogonal multiplexing distance of the adjacent cells is as follows
Figure FDA0002199378720000021
Wherein m and k are both positive integers, and m is 2k + 2;
s2, storing the orthogonal sequence set;
s3, when a user request control signal is received, reading available orthogonal sequences in the orthogonal sequence set;
and S4, receiving user request data, and outputting the user request data after spreading according to the available orthogonal sequence.
5. The method for spreading channels in a CDMA system according to claim 4, wherein said step S1 further comprises:
s11, selecting a vector semi-bent function of m input and k output;
s12, constructing 3 x 2 by using the vector semi-bent functionkA set of one of the orthogonal sequences,wherein the orthogonal sequence set has 2kThe number of sequences in the orthogonal sequence set is 2m-1A one, has 2k+1The number of sequences in the orthogonal sequence set is 2m-2A plurality of;
and S13, arranging the cells according to the orthogonal sequence set according to a preset rule, so that the sequences in the cells are mutually orthogonal, and the sequence sets of the adjacent cells are mutually orthogonal.
6. The method for spreading channels in a CDMA system according to claim 5, wherein said step S12 further comprises:
s121, obtaining 2 according to the vector semi-bent functionkA semi-bent function;
s122, selection 2m×2mA dimension Hadamard matrix, and dividing the Hadamard matrix into a first subsequence set, a second subsequence set and a third subsequence set, wherein the sequence number of the first subsequence set is 2m-1The number of sequences in the second subsequence set and the third subsequence set is 2m-2A plurality of;
s123, mixing the 2kMultiplying the corresponding bit of each semi-bent function with the corresponding bit of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2kA first set of orthogonal sequences, 2kA second set of orthogonal sequences, 2kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2m -2And (4) respectively.
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