CN101826890A - Implementation method of ZC (Zadoff-Chu) sequence in LTE (Long Term Evolution) system - Google Patents

Abstract

The invention provides an implementation method of a ZC (Zadoff-Chu) sequence in an LTE (Long Term Evolution) system. The sequence is calculated by using a recursion mode, i.e. a value after the sequence is obtained by multiplying a value before the sequence by a coefficient, and the value of xq(n) is obtained by multiplying the value of xq(n-1) by a coefficient, wherein the ZC sequence in the LTE system can be any one signal of basic signals of a main synchronizing signal, a random access signal and an upstream reference signal. In the method, a cosine operation each time is converted into a complex multiplication operation, thereby the time of a sine operation and a division is saved and the operand is greatly reduced. In the invention, the symmetry of the ZC sequence can also be utilized, only the value of a front half of the sequence is calculated, and the value of the rear half is obtained according to the symmetry, thereby the operand is further reduced.

Description

The implementation method of ZC sequence in the LTE system

Technical field

The present invention relates to the mobile communication technology field, particularly relate to the implementation method of ZC sequence in the 3G (Third Generation) Moblie long evolving system (hereinafter to be referred as LTE).

Background technology

The full name of ZC sequence is the Zadoff-Chu sequence, and it belongs to the class in the CAZAC sequence (Constant Amplitude Zero Autocorrelation sequences, constant mould and zero autocorrelation sequence).The formula of reduction of the ZC sequence of odd length is:

$x_q\left(n\right)=\exp (-\mathrm{j\πq}\frac{n(n+1)}{N})$ n＝0，L?N-1 (1)

Wherein, N represents sequence length, is odd number, and q represents sequence index.

Because the ZC sequence has the characteristic in constant mould and zero auto-correlation zone, therefore be widely used in the uplink and downlink system of LTE comprising the baseband signal in master sync signal, accidental access signal and the uplink reference signals as distinctive signal.

In 3GPP TS36.211-8.4.0 agreement, master sync signal x in the LTE system _q(n) be defined as:

$x_q\left(n\right)=\left\{\begin{array}{cc}{e}^{-j\frac{\mathrm{\πqn}(n+1)}{63}}& n=\mathrm{0,1},...,30\\ e^{-j\frac{\mathrm{\πq}(n+1)(n+2)}{63}}& n=\mathrm{31,32},...,61\end{array}\right.---\left(2\right)$

Wherein the value of q is 25,29 or 34.

Accidental access signal x in the LTE system _q(n) be defined as:

$x_q\left(n\right)=e^{-j\frac{\mathrm{\πqn}(n+1)}{N}},$ 0≤n≤N-1 (3)

Sequence length N=839, the span of q value is: the integer between 1 to 838, occurrence is indicated by high level.

Sequence length is greater than or equal to the baseband signal x in 36 the uplink reference signals in the LTE system _q(n) be defined as:

$x_q\left(n\right)=e^{-j\frac{\mathrm{\πqn}(n+1)}{N}},$ 0≤n≤N-1 (4)

Wherein,

The length N of ZC sequence is determined (N is the largest prime less than M) by the sub-carrier number M that distributes to Physical Uplink Shared Channel, and u is by the decision of group frequency hopping, span be u ∈ 0,1 ..., 29}, v determine by sequence hopping, span be v ∈ 0,1}.

They all have the feature of formula 1 as can be seen from formula 2-4.If consideration adopts formula 1 to calculate in real system, need to do N time cosine and sinusoidal computing so, cosine and sinusoidal computing are a kind of nonlinear computings, cosine repeatedly and sinusoidal computational complexity are very high, are unfavorable for the realization of hardware or software.Especially for random access leader sequence, the length N of this sequence=839 need to do 839 times cosine and sinusoidal computing so, and consuming time very long, such implementation method does not satisfy the demanding demand of LTE system real time.

Summary of the invention

The invention provides the implementation method of ZC sequence in a kind of LTE system, with the recursion mode sequence of calculation, value on dutyly obtains with coefficient Coeff_q with sequence is previous after the sequence, i.e. x _q(n) value x _q(n-1) on duty obtains with a coefficient Coeff_q, change cos operation each time into complex multiplication operation in this way, saved the time of sinusoidal computing and division, greatly reduced operand, the present invention also can utilize the symmetry of ZC sequence, the value of sequence of calculation the first half, half value of back obtains according to the sequence symmetry, has further reduced operand.

For reaching above purpose, the realization thinking of ZC sequence is in the LTE of the present invention system, the coefficient that calculates needs according to the length N and the sequence index value q of sequence

Mode with recursion calculates the value that the ZC sequence is had a few successively then.

It is as follows that it simplifies principle of operation:

$x_q\left(n\right)=e^{-j\frac{\mathrm{\πqn}(n+1)}{N}},$ 0≤n≤N-1 (5)

Initialization x _q(0)=1

$x_q\left(n\right)/x_q(n-1)=e^{-j\frac{\mathrm{\πqn}(n+1)}{N}}/e^{-j\frac{\mathrm{\πq}(n-1)n}{N}}$ (6)

$=e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H200910103294XE0000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;qn}}{N}},$ 1≤n≤N-1

Order

1≤n≤N-1, initialization a (0)=1

$a\left(n\right)/a(n-1)=e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H200910103294XE0000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;qn}}{N}}/e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H200910103294XE0000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;q}(n-1)}{N}}$

$=e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H200910103294XE0000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;qn}}{N}},$ 1≤n≤N-1

Order

And then obtain

a(n)＝a(n-1)×Coeff_q，1≤n≤N-1 (7)

According to formula 6 and formula 7, and x _q(0)=1, obtains

x _q(n)＝x _q(n-1)×a(n)，1≤n≤N-1 (8)

Wherein, x={x _q(0), x _q(1), L, x _qBe the sequence array (N-1) }, be used to deposit sequential value, a={a (0), a (1), L, a (N-1) be the coefficient array, be used to deposit coefficient value.

Its concrete operation step is as follows:

Determine the length N and the sequence index value q of sequence according to signal type;

To synchronizing signal, N=63, q=25,29 or 34 is determined by UE;

To accidental access signal, N=839, the span of q value is: the integer between 1 to 838, occurrence is indicated by high level;

To the baseband signal of uplink reference signals, N determines (N is the largest prime less than M) by the sub-carrier number M that distributes to Physical Uplink Shared Channel, and the q value is by group frequency hopping and sequence hopping decision.

According to the length N and the sequence index value q of sequence, calculate

Initialization a (0)=1 utilizes formula a (n)=a (n-1) * Coeff_q, and 1≤n≤N-1 calculates a (1)=a (0) * Coeff_q, a (2)=a (1) * Coeff_q, and the rest may be inferred, up to calculating a (N-1).

Initialization x _q(0)=1, utilizes formula x _q(n)=x _q(n-1) * and a (n), 1≤n≤N-1 calculates x _q(1)=x _q(0) * a (1), x _q(2)=x _q(1) * and a (2), the rest may be inferred, up to calculating x _q(N-1).

Can further utilize the symmetry of ZC sequence, simplify the value of (N+1)/2 point before calculating, according to the symmetry of ZC sequence, obtain the whole sequence value then

The symmetry proof is as follows:

$\frac{x_q\left(n\right)}{x_q(N-1-n)}=\frac{e^{-j\frac{\mathrm{\&pi;qn}(n+1)}{N}}}{e^{-j\frac{\mathrm{\&pi;q}(N-1-n)(N-n)}{N}}}=e^{j\frac{\mathrm{\&pi;q}(N^2-\mathrm{Nn}-N+n-\mathrm{Nn}+n^2-n^2-n)}{N}}$

$=e^{j\frac{\mathrm{\&pi;q}(N^2-2\mathrm{Nn}-N)}{N}}=e^{\mathrm{j\&pi;q}(N-2n-1)}---\left(9\right)$

Analyze: no matter n gets any value, and 2n is an even number; N is an odd number, and N-1 is an even number so; So N-2n-1 is an even number, so e ^{J π q (N-2n-1)}Be constantly equal to 1.

Therefore no matter why sequence index q is worth x _q(n) all have symmetry, be expressed as x _q(n)=x _q(N-1-n).

In addition, because the generation formula 2 of synchronizing signal has difference slightly with the fundamental formular (formula 1) of ZC sequence, the sequence length of the baseband signal of accidental access signal and uplink reference signals all is N, and the sequence length of synchronizing signal is N-1, thereby it is slightly variant to make the synchronizing signal symmetry represent, its symmetry is expressed as x _q(n)=x _q(N-2-n).

Wherein, x={x _q(0), x _q(1), L, x _qBe the sequence array (N-1) }, be used to deposit sequential value, a={a (0), a (1), L, a (N-1) be the coefficient array, be used to deposit coefficient value.

Carry out complexity relatively with the method (formula 8) that the method that defines in the agreement (formula 1) and the present invention propose, as table 1.

Table 1

The method that proposes with the present invention can reduce the operation times of cosine, sine and real number division greatly as can be seen from Table 1, and especially the N value is big more, reduces obvious more.When considering that software is realized, the instruction cycle that complex multiplication needs was lacked than the instruction cycle that cosine calculating needs, and had also saved the time of real number division and sinusoidal computing simultaneously with formula 8, greatly reduced the complexity of computing.

Description of drawings

Fig. 1 is a ZC sequence recursion implementation method;

Fig. 2 is an implementation method of utilizing the symmetric recursive algorithm of ZC sequence.

Embodiment

In order to make purpose of the present invention, technical scheme and advantage clearer,, the implementation method of ZC sequence in a kind of LTE of the present invention system is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.

ZC sequence recursion implementation method in a kind of LTE of the present invention system, as shown in Figure 1, it comprises the steps:

Step 101: determine the length N and the sequence index value q of sequence according to different signal types, signal type is a synchronizing signal in the present embodiment, value N=63, q=25;

Optionally, as another kind of embodiment, signal type is an accidental access signal, N=839, and the span of q value is: the integer between 1 to 838, occurrence is indicated by high level;

Optionally, as another kind of embodiment, signal type is the baseband signal of uplink reference signals, and N is determined that by the sub-carrier number M that distributes to Physical Uplink Shared Channel the q value is by group frequency hopping and sequence hopping decision;

Wherein, when signal type was the baseband signal of uplink reference signals, N was the largest prime less than M.

Step 102: determine the length N and the sequence index value q of sequence, design factor according to signal type

Step 103: initialization a (0)=1 utilizes formula a (n)=a (n-1) * Coeff_q, and 1≤n≤N-1 calculates a (1)=a (0) * Coeff_q, a (2)=a (1) * Coeff_q, and the rest may be inferred, up to calculating a (N-1);

Step 104: initialization x _q(0)=1, utilizes formula x _q(n)=x _q(n-1) * and a (n), 1≤n≤N-1 calculates x _q(1)=x _q(0) * a (1), x _q(2)=x _q(1) * and a (2), the rest may be inferred, up to calculating x _q(N-1).

Optionally, as another kind of embodiment, step 103 to step 104 can be taked an a (n) and an x _q(n) account form one to one.

Wherein, N represents sequence length, is odd number, and q represents sequence index value, x={x _q(0), x _q(1), L, x _qBe the sequence array (N-1) }, be used to deposit sequential value, a={a (0), a (1), L, a (N-1) be the coefficient array, be used to deposit coefficient value.

Utilize symmetric ZC sequence implementation method in a kind of LTE of the present invention system, as shown in Figure 2, it comprises the steps:

Step 201: determine the length N and the sequence index value q of sequence according to different signal types, signal type is a synchronizing signal in the present embodiment, value N=63, q=25;

Optionally, as another kind of embodiment, signal type is an accidental access signal, N=839, and the span of q value is: the integer between 1 to 838, occurrence is indicated by high level;

Optionally, as another kind of embodiment, signal type is the baseband signal of uplink reference signals, and N is determined that by the sub-carrier number M that distributes to Physical Uplink Shared Channel the q value is by group frequency hopping and sequence hopping decision;

Wherein, when signal type was the baseband signal of uplink reference signals, N was the largest prime less than M.

Step 202:, calculate according to the length N and the sequence index value q of sequence

Step 203: initialization a (0)=1 utilizes formula a (n)=a (n-1) * Coeff_q to calculate a (1)=a (0) * Coeff_q, a (2)=a (1) * Coeff_q, and the rest may be inferred, up to calculating a ((N-1)/2)

Step 204: initialization x _q(0)=1, utilizes formula x _q(n)=x _q(n-1) * and a (n), calculate x _q(1)=x _q(0) * a (1), x _q(2)=x _q(1) * and a (2), the rest may be inferred, up to calculating x _q((N-1)/2)

Optionally, as another kind of embodiment, step 203 to step 204 can be taked an a (n) and an x _q(n) account form one to one.

Step 205: utilize symmetry, obtain x _q((N-1)/2+1), L x _q(N-1).

Wherein, when signal type was the baseband signal of accidental access signal and uplink reference signals, the symmetry calculating formula was x _q(n)=x _q(N-1-n); When signal type was synchronizing signal, the symmetry calculating formula was x _q(n)=x _q(N-2-n).

Wherein, N represents sequence length, is odd number, and q represents sequence index value, x={x _q(0), x _q(1), L, x _qBe the sequence array (N-1) }, be used to deposit sequential value, a={a (0), a (1), L, a (N-1) be the coefficient array, be used to deposit coefficient value.

It will be apparent to those skilled in the art that and understand, system and method for the present invention for above embodiment only be used to illustrate the present invention, and be not limited to the present invention.Though effectively described the present invention by embodiment, one skilled in the art will appreciate that there are many variations in the present invention and do not break away from spirit of the present invention.Under the situation that does not deviate from spirit of the present invention and essence thereof, those skilled in the art work as can make various corresponding changes or distortion according to the inventive method, but these corresponding changes or distortion all should be included within protection scope of the present invention.

Claims (7)

1.LTE the implementation method of ZC sequence is characterized in that in the system, with the recursion mode sequence of calculation, value on dutyly obtains with coefficient Coeff_q with sequence is previous after the sequence, and concrete steps are:

Determine the length N and the sequence index value q of sequence according to signal type;

Design factor $\mathrm{Coeff}\_q=e^{-j\frac{2\mathrm{\&pi;q}}{N}};$

Initialization a (0)=1 utilizes formula a (n)=a (n-1) * Coeff_q, and 1≤n≤N-1 calculates a (1)=a (0) * Coeff_q, a (2)=a (1) * Coeff_q, and the rest may be inferred, up to calculating a (N-1);

Initialization x _q(0)=1, utilizes formula x _q(n)=x _q(n-1) * and a (n), 1≤n≤N-1 calculates x _q(1)=x _q(0) * a (1), x _q(2)=and xq (1) * a (2), the rest may be inferred, up to calculating x _q(N-1);

Wherein, N represents sequence length, is odd number, and q represents sequence index value, x={x _q(0), x _q(1), L, x _qBe the sequence array (N-1) }, be used to deposit sequential value, a={a (0), a (1), L, a (N-1) be the coefficient array, be used to deposit coefficient value.

2. the implementation method of ZC sequence is characterized in that in the LTE as claimed in claim 1 system, and described signal type is meant any one signal in the baseband signal in master sync signal, accidental access signal and the uplink reference signals in the LTE system.

3. the implementation method of ZC sequence is characterized in that in the LTE as claimed in claim 1 or 2 system, when described signal type is meant master sync signal in the LTE system, and its parameter N=63, q=25,29 or 34, q is determined by UE.

4. the implementation method of ZC sequence in the LTE as claimed in claim 1 or 2 system, it is characterized in that, when described signal type is meant accidental access signal in the LTE system, its parameter N=839, the span of q value is: the integer between 1 to 838, occurrence is indicated by high level.

5. the implementation method of ZC sequence in the LTE as claimed in claim 1 or 2 system, it is characterized in that, when described signal type is meant baseband signal in the uplink reference signals in the LTE system, its parameter N is determined that by the sub-carrier number M that distributes to Physical Uplink Shared Channel the q value is by group frequency hopping and sequence hopping decision.

6. the implementation method of ZC sequence is characterized in that described parameter N determines that by the sub-carrier number M that distributes to Physical Uplink Shared Channel method is that N is the largest prime less than M in the LTE as claimed in claim 5 system.

7. as the implementation method of ZC sequence in each described LTE system of claim 1-6, it is characterized in that utilize the symmetry of ZC sequence, the value of (N+1)/2 point before calculating according to the symmetry of ZC sequence, obtains the whole sequence value then;

Wherein, when signal type was the baseband signal of accidental access signal and uplink reference signals, the symmetry calculating formula was x _q(n)=x _q(N-1-n); When signal type was synchronizing signal, the symmetry calculating formula was x _q(n)=x _q(N-2-n);

Wherein, N represents sequence length, is odd number, and q represents the sequence index value, 1≤n≤N-1.

Images