CN108174447B

CN108174447B - Mobile communication system

Info

Publication number: CN108174447B
Application number: CN201711449702.8A
Authority: CN
Inventors: 张卫国; 闫家伟
Original assignee: Xi'an Yuran Information Technology Co Ltd
Current assignee: Xi'an Yuran Information Technology Co ltd
Priority date: 2017-12-27
Filing date: 2017-12-27
Publication date: 2020-08-04
Anticipated expiration: 2037-12-27
Also published as: CN108174447A

Abstract

The present invention relates to a mobile communication system, comprising: a base station controller for generating an orthogonal sequence and allocating an orthogonal sequence resource to each base station in the cellular network according to a predetermined rule; and the base stations form a cellular network after being arranged and are used for distributing channel resources according to the orthogonal sequence resources. The mobile communication system 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 the cell and solve the problem that the communication cannot be normally carried out due to too many users.

Description

Mobile communication system

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a mobile communication system.

Background

The design of a CDMA (Code Division Multiple Access) system is generally based on a length of 2^mThe use of (binary) orthogonal sequences (codewords). Even if the whole space has

Individual 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 sequences in non-adjacent cells should be small enough 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, see "W. -G.Zhang, C. -L. Xie, and E.Pasalic," L image Sets of organic Sequences available for Applications in CDMASystems, "IEEE Transactions on Information Theory, vol.62No.6, pp.3757-3767, June 2016.) that generates a large set of sequences that are orthogonal to each other (in each set), with most of the sets of sequences also being orthogonal to each other, by first covering the parity of m and then avoiding the difficult combination of assigning orthogonal sets of sequences to the same cell and ensuring orthogonality among adjacent cells, which is achieved by a number of 2 users per cell^m-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 mobile communication system capable of improving user capacity and having strong interference resistance.

In order to achieve the purpose of the invention, the invention adopts the technical scheme that:

a mobile communication system comprising:

a base station controller for generating an orthogonal sequence and allocating an orthogonal sequence resource to each base station in the cellular network according to a predetermined rule;

and the base stations form a cellular network after being arranged and are used for distributing channel resources according to the orthogonal sequence resources.

In a specific embodiment, the base station includes: the base station transceiver is used for converting the communication data into radio frequency signals and then sending the radio frequency signals out through the antenna or converting the radio frequency signals received through the antenna into the communication data.

In a specific embodiment, the generating the orthogonal sequence includes:

selecting a vector semi-bent function with m input and k output, wherein m and k are positive integers, and m is 2k + 2;

constructing 3 × 2 using the vector semi-bent function^kA set of orthogonal sequences, wherein there are 2 in the set of orthogonal sequences^kThe number of sequences in the orthogonal sequence set is 2^m-1A one, has 2^k+1The number of sequences in the orthogonal sequence set is 2^m-2And (4) respectively.

In one embodiment, the constructing 3 × 2 using the vector semi-bent function^kThe set of orthogonal sequences includes:

obtaining 2 according to the vector semi-bent function^kA semi-bent function;

option 2^m×2^mA 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 2^m-1The number of sequences in the second subsequence set and the third subsequence set is 2^m-2A plurality of;

2 is to be^kThe corresponding bits of the semi-bent function are multiplied by the corresponding bits of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2^kA first set of orthogonal sequences, 2^kA second set of orthogonal sequences, 2^kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2^m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2^m ^-2And (4) respectively.

In a specific embodiment, the predetermined rule includes: the sequences within the cells are made orthogonal to each other and the sets of sequences of adjacent cells are made orthogonal to each other.

In a specific embodiment, the orthogonal multiplexing distance of the adjacent cells is

The mobile communication system 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 the cell and solve the problem that the communication cannot be normally carried out due to too many users.

Drawings

Fig. 1 is a block diagram of a mobile communication system according to an embodiment of the present invention;

fig. 2 is a flowchart of orthogonal sequence generation provided in an embodiment of the present invention;

fig. 3 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 mobile communication system according to an embodiment of the present invention, including:

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 with

Is a vector space of dimension m and is,

is a finite field over GF (2), then the m-ary Boolean function f (x) is expressed as a certain value

To

Is here mapped to

Let B_mRepresenting the set of all m-ary Boolean functions the present invention uses "+" and ∑_iTo replace

And

any Boolean function f ∈ B_mCan be represented by its algebraic formal:

wherein

The algebraic degree of f (x) is such that_bMinimum value of wt (b) not equal to 0, denoted as deg (f), where wt (b) is the Hamming weight of b. When deg (f) is 1, f is called an affine function.

For the

The inner product of a and b is defined as:

where the addition is a modulo-2 operation.

At will

The linear function above can be defined by the inner product ω · x. Where ω is (ω)₁,...,ω_m),

And each omega distinguishes a different linear function. Bag (bag)The set containing all m element linear functions is defined as

Thus, it is possible to provide

Let B_mRepresenting the set of all m-ary Boolean functions, for an arbitrary f ∈ B_mThe Walsh spectrum is defined as follows:

definition of

Support set for function f if an m-ary function f ∈ B_mThe truth table of (2) is called a balance function if the numbers of 0 and 1 are equal, i.e., # supp (f) ═ 2^m-1Or is:

W_f(0_m)＝0 (4)

wherein 0_mThe m long 0 vectors are shown.

Function f ∈ B_mIs a sequence of length N-2^mThe (1, -1) sequence of (a), defined as:

vector quantity

And

expressed as

Is defined as:

thus it can be derived

Where l ═ ω · x.

A 2^m×2^mOf the Hadamard matrix

Is defined as:

let r be_j,0≤j≤2^m-1 is

Column j of (1), then r_jIs a linear sequence, i.e. a set

H＝{r_j|0≤j≤2^m-1} (8)

Is a set of Hadamard sequences of sequence numbers,

according to the above scheme, the present invention provides the following definitions:

definition 1: let f₁,f₂∈B_m. If so:

namely, it is

And

is orthogonal with

And (4) showing. Order to

If set S

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 arbitrary

Always have

Then call S₁,S₂Is orthogonal, with S₁⊥S₂And (4) showing.

The invention derives the following properties of orthogonal sequences:

introduction 1: let f₁,f₂∈B_m. Then

If and only if

For any two different linear functions/,

W_l+l′(0_m) 0, then

The overall result is that H is a set of orthogonal sequences.

Definition 2: if for any

W_f(α)∈{0,±2^λWhere λ ≧ m/2 is a positive integer, this function f is called the Plateaued function. When in use

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:

wherein phi is

To

And g ∈ B_s。

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 F:

the t-ary Boolean function set F (x) ═ f can also be considered₁,...,f_t). If component function f₁,...,f_tIs a spectral value taken from {0, + -2 }^λThe ternary planeaued boolean function of F is then called a vector planeaued function. When in use

F is called the vector semi-bent function. If component function f₁,...,f_tIs a spectral value taken from { + -2^m/2A binary best function, then called F a vector semi-best function, where m is an even number and t ≦ m/2.

Based on the above definition of the present invention, please refer to fig. 2, where fig. 2 is a flowchart for generating an orthogonal sequence according to an embodiment of the present invention, and the flowchart includes:

In one embodiment, the constructing 3 × 2 by using the vector semi-bent function^kThe set of orthogonal sequences includes a set of orthogonal sequences,

obtaining 2 according to the vector semi-bent function^kA semi-bent function;

specifically, in order to increase the number of users in a cell, m and k are two positive integers, where m is 2k +2, and k is greater than or equal to 2. Let gamma be

And {1, γ^k-1Is as

On the upper part

A set of polynomial bases. Define isomorphic mapping π:

π(b₁+b₂γ+…+b_kγ^k-1)＝(b₁,b₂,...,b_k) (13)

let bijective phi for i 1_i:

Is defined as:

wherein [ y ] is defined as an integer representation of y.

Let y be a positive integer of one,

for i 1.. k, a series of boolean functions f are defined_i:

f_i(y,x,z)＝φ_i(y)·x (15)

Vector boolean function F:

is defined as:

F(x)＝(f₁,...,f_k) (16)

in particular, for any

Order to

f_c(y,x,z)＝c·F(y,x,z)＝c₁f₁+...+c_kf_k(17)

For arbitrary fixation

Defining:

let T₀＝L₀₀∪L₁₁，T₁＝L₀₁And T₂＝L₁₀。

Specifically, the structure 3.2^kThe disjoint sequence sets are as follows:

wherein S is_c,0The sequence has 2^m-1One user, the other sequence has 2^m-2And (4) 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

Order sequence set S_c,iAs defined in equation (19), then, there is:

i) for any one

Has | S_c,0|＝2^m-1，|S_c,1|＝|S_c,2|＝2^m-2。

ii) for any

S_c,iIs an orthogonal semi-bent sequence set.

iii) for any

S_c,i⊥S_c′,i′If and only if i ≠ i'.

First, note | L|＝2^2k＝2^m-2This indicates that i) is true.

Secondly, for ii), for any

And is

Is provided with

Wherein

Due to the fact that

And

wherein for

When it is established, when γ is

When the primitive element is present, only one i is more than or equal to 0_c≤2^k-2, such that

Can know phi_c(y) is

One permutation of (a). There is therefore a single

So that phi is_c(y) α, which indicates for any

Is provided with

For any of the β, the method may be,

is provided with

In addition to this, the present invention is,

for arbitrary

Is provided with

When k is (m-2)/2, F is a vector semi-bent function.

Again, for iii), let

Wherein l ∈ T_i，l′∈T_i′。

To analyze

And

in consideration of orthogonality therebetween

h＝(f_c+l)+(f_c′+l′)＝f_c+c′+(l+l′) (27)

Wherein

Because of the fact that

So equation f_c+f_c′＝f_c+c′Can be easily obtained from the formula (21).

By equation (26), W_h(0_m) 0 if and only if

As can be seen from table 1, it is,

if and only if i ≠ i'. This means S_c,i⊥S_c′,i′If and only if i ≠ i'.

Table 1: t is_iOperation of

Example two

The following example gives the orthogonal sequence S when m is 8_c,iDistribution of (S)_c,0Equivalent to a cell with a greater number of users 2^m-1。

When m is 8, k is 3, which is known from example 1 to yield 3 × 2³24 disjoint orthogonal semi-bent sequences,

S_c,0the sequence has 2^m-1The remaining sequence has 64 users, and the sequence is divided into 128 usersThe cells are arranged according to a predetermined rule by orthogonal sequence sets so that the sequences in the cells are orthogonal to each other and the sequence sets of adjacent cells are orthogonal to each other. Referring to fig. 3, fig. 3 is a schematic diagram of a regular hexagonal network distribution according to an embodiment of the present invention, wherein the reusable distance is

Wherein, the larger font is marked with 2^m-1The cell of an individual user. Note that each cell is surrounded by 6 small cells, while each small cell is surrounded by 3 large cells and 3 small cells. In addition, two adjacent 2 s are viewed from a certain column^m-1The cells of each user are separated by two 2^m-2The cell of a subscriber, which means that one third of the cells in the network has 2^m-1A large cell of individual users. For example, S_000,0S in the same column_001,0Is spaced by s_000,1And s_000,2Two cells.

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

1. A mobile communication system, comprising:

a base station controller for generating an orthogonal sequence and allocating an orthogonal sequence resource to each base station in the cellular network according to a predetermined rule; the predetermined rule includes: making the sequences within the cells orthogonal to each other and the sets of sequences of adjacent cells orthogonal to each other;

a plurality of base stations, which are arranged to form a cellular network and are used for allocating channel resources according to the orthogonal sequence resources;

wherein the generating the orthogonal sequence comprises:

obtaining 2 according to the vector semi-bent function^kA semi-bent function;

2 is to be^kThe corresponding bits of the semi-bent function are multiplied by the corresponding bits of the first subsequence set, the second subsequence set and the third subsequence set respectively to obtain 2^kA first set of orthogonal sequences, 2^kA second set of orthogonal sequences, 2^kA third orthogonal sequence set, wherein the number of sequences in the first orthogonal sequence set is 2^m-1The second orthogonal sequence set and the third orthogonal sequence set are both 2^m-2And (4) respectively.

2. The mobile communication system according to claim 1, wherein the orthogonal multiplexing distance between the adjacent cells is