CN1430359A - Method of realizing calling time selection under idle mode by mobile telephone user's terminal - Google Patents

Abstract

The present invention relates to a method for realizing paging time selection, which is a formula for selecting paging time when a mobile user terminal is in idle mode: PO=(IMSI divK)mod(DRX cycle length)+n ^* (DRX cycle length), design An operation procedure with small calculation amount, simple algorithm implementation and good versatility is proposed, which can adapt to the situation of global mobile subscriber identifier (IMSI) with any number of digits (m), and is applied to frequency division multiplexing wideband code division multiple access mobile communication system, its basic method is also suitable for time-division multiplexing mode. Its processing steps start from the input parameters, including IMSI, discontinuous reception cycle length (DRX cyclelength), the number K of auxiliary common control physical channels carrying the paging channel, and the maximum value MAXSFN of the cell system frame number. The number of digits is operated by two cycles of 2, 3, ..., m and n=0, 1, 2, ..., and the PO value smaller than MAXSFN is recorded until the PO value is greater than or equal to MAXSFN.

Description

Implementation method for mobile user terminal to select paging time in idle mode

technical field

The present invention relates to the technical field of the third-generation Wideband Code Division Multiple Access (WCDMA) mobile communication system, and more precisely relates to the selection of the paging time ( PO: Paging Occassion) implementation method.

Background technique

In order to realize the discontinuous reception (DRX) of the user terminal (UE) in the idle mode, the third generation mobile communication system WCDMA 25304 v3. Here, only one paging indicator (PI: Page Indicator) of a paging time (PO: PagingOcassion) needs to be monitored.

Specifically, in the idle mode, the user terminal can use the discontinuous reception (DRX) method to reduce power consumption. When using the discontinuous reception (DRX) method, at the paging time of each discontinuous reception cycle, the mobile The user terminal only needs to monitor one paging indicator (PI).

The length of the discontinuous reception cycle (DRX cycle length) should be MAX(2 ^k , PBP) frame, that is, take the maximum among 2 ^K and PBP, where k is {3, 4, 5, 6, 7, 8, 9} an integer, PBP is the paging block period (Paging Block Periodicity). The Paging Block Period (PBP) applies only in Time Division Duplex (TDD) mode and is equal to the Paging Indicator Channel (PICH) repetition period in system information broadcasts. In the frequency division duplex (FDD) mode, the paging block period PBP=1.

The user terminal (UE) can be attached to different core networks (CN) with a specific discontinuous reception cycle length (DRX cyclelength), and the user terminal (UE) will save the specific discontinuous reception cycle of each core network (CN) to which it belongs length (DRX cycle length), and use the shortest of these discontinuous reception cycle lengths (DRX cycle length). The Core Network Circuit Switched Domain (CS CN) specific discontinuous reception (DRX) cycle length coefficient shall be updated in the user information in the user terminal (UE) given by the system information. On the other hand, after the user terminal (UE) negotiates with the core network packet switching domain (PS CN), the non-access stratum (NAS) process updates the core network packet switching (PS CN) specific discontinuous reception (DRX) cycle length factor. If no negotiated value "k" is specified during the non-access stratum (NAS) process, the user terminal (UE) and the core network packet switched domain (PS CN) will use the core network packet switched domain (PS CN) given by the system information ) of the discontinuous reception (DRX) cycle length.

The Discontinuous Reception (DRX) cycle length for the Universal Terrestrial Radio Access Network (UTRAN) connection mode, which is the minimum of the following values:

1. Universal terrestrial radio access network discontinuous reception cycle length (UTRAN DRX cycle length);

2. Any stored core network-specific discontinuous reception cycle length (DRX cycle length), these core networks are core networks (CN) that have not yet established a signaling connection in the core network to which the user terminal (UE) is connected.

For the frequency division duplex (FDD) mode, the user terminal must monitor the paging indicator (Paging Indicator) of the paging indication channel (PICH) frame number in the cell system frame number (SFN) given by the paging moment.

For Time Division Duplex (TDD) mode, the user terminal (UE) has to monitor the paging indications in the paging block given by the paging occasion. The paging instant gives the cell system frame number (SFN) of the first frame in the paging block.

The value of paging occasion (PO) is determined by the following formula:

PO＝{(IMSI div K)mod(DRX cycle length div PBP)}*PBP

+n*DRX cycle length+Frame Offset.

In the formula, IMSI represents the global mobile subscriber identifier, div is the division symbol, K is equal to the number of the secondary common control physical channel (SCCPCH) carrying the paging channel (PCH), and a mod b represents the integer a divided by the integer b The remainder, DRX cycle length represents the length of the discontinuous reception cycle, n=0, 1, 2,..., Frame Offset represents the frame offset.

For frequency division multiplexing mode, the frame offset Frame Offset=0; for time division multiplexing mode, the frame offset value of the paging indication channel is given in the system message; PBP indicates the paging block period, and the paging block period only applies In time division duplex (TDD) mode, and equal to the repetition period of the paging indicator channel (PICH) in the system information broadcast, for frequency division duplex (FDD) mode, the paging block period (PBP) is equal to 1. It is required that the calculated paging time (PO) value is smaller than the maximum value of the system frame number (SFN) of the cell.

For frequency division duplex (FDD) mode, because the frame offset Frame Offset=0 and PBP=1, the above formula can be simplified as:

PO=(IMSI div K)mod(DRX cycle length)+n*(DRX cycle length).

If the user terminal (UE) does not have a global mobile subscriber identity (IMSI), the user terminal (UE) uses default values: IMSI=0, DRX cycle length=256, that is, the discontinuous reception cycle length is 2.56 seconds.

Since the Global Mobile Subscriber Identifier (IMSI) is generally a 15-digit decimal integer, and an unsigned 32-bit long integer can only represent a maximum of 10 decimal digits, that is, 4294967296, it is stipulated in the WCDMA25304 v3.7.0 protocol , for the selection formula of the paging time in the frequency division duplex mode (FDD), as shown in the above simplified formula, the global mobile subscriber identifier (IMSI) in the formula sometimes cannot be directly used by an unsigned long integer variable storage.

The traditional implementation technology is to use two unsigned long integer variables ulLow and ulHigh to store, assuming that the global mobile subscriber identity (IMSI) is a decimal number less than or equal to 16 digits, then use the long integer variable ulLow to save the decimal value. The low 8 bits of the global mobile subscriber identifier (IMSI), and the remaining high digits-high 8 bits of the decimal global mobile subscriber identifier (IMSI) are saved with the long integer variable ulHigh, and the specific implementation scheme of selecting the paging time PO is: Paging Occasion＝((((ulHigh-ulHigh mod K)div K)×10 ⁸ )mod(DRX cycle length)+(((ulHigh mod K)×10 ⁸ +ulLow)div K)mod(DRX cycle length)) mod(DRX cycle length)+n×(DRX cycle length).

Obviously, the above-mentioned implementation scheme is not only complicated but also not flexible enough and universal. For example, when the global mobile subscriber identifier (IMSI) is a 24-bit decimal number, three unsigned long integer variables must be put together to meet the storage requirements. It is also necessary to redesign the implementation algorithm, and as the number of digits of the global mobile subscriber identifier (IMSI) increases, more and more long integer variables are required to save the IMSI, and the implementation algorithm will be more complicated.

Contents of the invention

The purpose of the present invention is to design a method for a mobile user terminal to select a paging time in idle mode. It is a method for selecting a paging time (PO) formula in idle mode. Mobile Subscriber Identity (IMSI), and the implementation process is simple.

The technical scheme that realizes the object of the present invention is such: a kind of implementation method that mobile user terminal selects paging time under idle mode, is applied in frequency division multiplexing wideband code division multiple access mobile communication system, is characterized in that comprising the following processing step:

A. Input parameters, including the global mobile subscriber identifier (IMSI) of m bits, the length of the discontinuous reception cycle, the number K of the secondary common control physical channel (SCCPCH) carrying the paging channel (PCH), and the cell system frame The maximum value (MAXSFN) of the number (SFN);

B. a local variable sum is set, and the initial value of the local variable sum is assigned as the first digit value of the global mobile subscriber identifier (IMSI);

C. Let the new local variable sum be equal to: the remainder of the original local variable sum (integer) divided by the discontinuous receiving cycle length (integer) of K times;

D. Assign the initial value of the first loop variable i to 2;

E. judge whether the value of the 1st loop variable i is less than or equal to the digit m of global mobile subscriber identity (IMSI), if then execute step F, if not then execute step G;

F. Let the new local variable sum be equal to: the sum (integer) of the numerical value of the i-th position in the former local variable sum of 10 times and the global mobile subscriber identifier is divided by the remainder of the discontinuous reception cycle length (integer) of K times again, And let the first loop variable i automatically increase by 1, and return to step E to continue execution;

G. Make the new local variable sum equal to: the integer part after dividing the original local variable sum (integer) by K (integer);

H. The second loop variable n is set, and the initial value of n is assigned as 0, and p is used to represent the number of selected paging moments (PO), and p is set to 0;

1. Let the paging moment (PO) be equal to the sum of the present value of the local variable sum and the discontinuous reception cycle length of n times;

J. Judging whether the paging time (PO) is less than the maximum value (MAXSFN) of the cell system frame number, if the paging time (PO) is less than the maximum value (MAXSFN), then perform step K, if the paging time (PO) is greater than or equal to the maximum value (MAXSFN), then execute step L;

K. the paging moment (PO) under the current n value is recorded as PO _n , let p be equal to n+1 and allow n to automatically add 1 and then jump back to step I to execute;

L. Submit all paging time (PO) values obtained through the above steps and corresponding to each value of n, PO ₀ , PO ₁ , PO ₂ , . . . , PO _p-1 .

The length of the discontinuous reception cycle in the step A is one of 8, 16, 32, 64, 128, 256, 512, and the maximum value of the system frame number (SFN) of the cell is 4095.

The m global mobile subscriber identifier (IMSI) in the step A is a decimal number, expressed as: IMSI=a ₁ a ₂ ... a _m-1 a _m , a ₁ is the first digit, a _i is wherein The i-th digit, 0≤a _i ≤9.

In the step A, when the mobile user terminal has no global mobile subscriber identity (IMSI), use the default value: IMSI=0, and let the discontinuous reception cycle length be 2.56 seconds.

In the step F, a counter is used to automatically increment the first loop variable i by 1.

In the step K, two counters are used to automatically add 1 to the number p of valid paging times and the second loop variable n respectively.

Also comprise the method that realizes calculating paging indicator (PI), and paging indicator (PI) is equal to: the integer part after dividing 8192 with m global mobile subscriber identifier (IMSI) is divided by the remainder of integer Np again, and Np is each The number of paging indicators in the frame, Np in the frequency division multiplexing mode is taken as one of 18, 36, 72, and 144.

The present invention represents the global mobile subscriber identifier (IMSI) as:

IMSI＝a ₁ a ₂ ... a _m-1 a _m

＝a ₁ ×10 ^m-1 +a ₂ ×10 ^m-2 +…+a _m-1 ×10 ¹ +a _m

=(((10×a ₁ +a ₂ )×10+a ₃ )×10+…+a _m-1 )×10+a _m ,

0≤a _i ≤9, the number of digits of the global mobile subscriber identity (IMSI) is m.

The present invention repeatedly utilizes three mathematical formulas derived: (a*b)mod c=((a mod c)*(b modc))mod c; (a div b)mod c=(a mod(b*c ))div b; and (a+b)mod c=(a mod c+b mod c)mod c, and applied to the paging time (PO) selection formula in the idle mode, in the time division multiplexing mode, PO＝{(IMSI div K)mod(DRX cycle lengthdiv PBP)}*PBP+n*DRX cycle length+Frame Offset, and in frequency division mode, because PBP＝1, Frame Offset＝0, it is simplified as: PO=(IMSI div K)mod(DRX cycle length)+n*(DRX cycle length).

The method of the present invention compares with the traditional implementation method of saving the Global Mobile Subscriber Identifier (IMSI) by using spelling length, the technical solution of the present invention's realization of the paging time (PO) calculation formula has the advantages of small amount of calculation, The algorithm has the characteristics of simple implementation and good versatility.

Description of drawings

Fig. 1 is a flow diagram of the present invention to realize the calculation formula of the paging time in the frequency division multiplexing mode.

Detailed ways

The invention provides a general, simple and efficient method for realizing the calculation and selection formula of the paging time in the idle mode.

We assume that the global mobile subscriber identifier IMSI=a ₁ ... a _m-1 a _m is an m-digit decimal number, m is a positive integer, and any one (i-th) decimal number is expressed as a _i , 0≤a _i ≤ 9, i=1, 2, ..., m, a ₁ indicates the highest bit of the IMSI, and a _m indicates the lowest bit of the IMSI. It is known that the calculation formula of the paging time (PO: Paging Occasion) in frequency division duplex (FDD) idle mode is:

PO=(IMSI div K)mod(DRX cycle length)+n*(DRX cycle length), where IMSI represents the global mobile subscriber identifier, and K is equal to the secondary common control physical channel (SCCPCH) carrying the paging channel (PCH) DRX cycle length indicates the discontinuous reception cycle length, positive integer n=0, 1, 2, ..., 4095, and the paging time (PO) value obtained is required to be less than the maximum value of the cell system frame number (SFN). In the formula, if the user terminal (UE) does not have a global mobile subscriber identity (IMSI), the user terminal (UE) uses the default value: IMSI=0; the discontinuous reception cycle length is 2.56 seconds (DRXcycle length=256).

Since the technical implementation of the paging time selection formula in time division duplex (TDD) idle mode is similar to the technical implementation of the paging time selection formula in frequency division duplex (FDD) idle mode, only the frequency division is given in this embodiment. The technical implementation scheme of the paging time calculation formula in multiplexing (FDD) idle mode.

Referring to Fig. 1 in combination, it is the technical steps to realize the paging time calculation formula under frequency division duplex (FDD) idle mode, including:

Step 1, enter the global mobile subscriber identifier (IMSI), the length of the discontinuous reception cycle (DRX cyclelength=8, 16, 32, 64, 128, 256 or 512), and the auxiliary The number K of the common control physical channel (SCCPCH), and the maximum value (MAXSFN) of the cell system frame number (SFN);

Step 2: Set a local variable sum, and assign the initial value of the local variable sum to the first digit value a ₁ of the IMSI, that is, sum=a ₁ ;

Step 3: Calculate sum=sum mod(DRX cycle length×K), that is, let the new local variable sum be equal to the remainder of the original local variable sum divided by K times the discontinuous reception cycle length (DRX cycle length*K);

Step 4: Assign an initial value of 2 to the first loop variable i, i.e. i=2;

Step 5: Determine whether the value i of the first loop variable is less than or equal to the digit m of the decimal IMSI, i.e. i≤m, if so, execute step 6, if not, execute step 7;

Step 6: When i≤m, let the new local variable sum equal to 10 times the sum of the original local variable sum and the decimal value of the i-th global mobile subscriber identifier, sum=(10*sum+a _i ), divide again Take the remainder of the discontinuous reception cycle length (DRX cycle length×K) of K times, that is, sum=(10×sum+ai)mod(DRX cycle length×K), let the first cycle variable i automatically increase by 1 after the execution is completed , i=i+1, and return to step 5 to continue execution, the automatic addition of 1 to the first loop variable i can be completed by a counter, and steps 5 and 6 constitute the first loop in the flow process;

Step 7: When i>m, make the new local variable sum equal to the integer part of the original local variable sum divided by K, that is, sum=sum div K, for example, 81 div 4=20, that is, keep the integer part 20 of 20.25 and discard it The fractional part of 20.25 is 0.25;

Step 8: the 2nd loop variable n is set, the initial value is 0 to n assignment, n=0, the number of the paging time (PO) that has been selected (promptly effective) is expressed with p, puts p to be 0, p = 0;

Step 9: Let the paging time (PO) be equal to the sum of the present value of the local variable sum and n times the length of the discontinuous reception cycle, Paging Occasion=sum+n×DRX cycle length,

Step 10: Determine whether the paging time (PO) is less than the maximum value (MAXSFN) of the cell system frame number, that is, Pagin Occasion<MAXSFN, if the paging time (PO) is less than the maximum value (MAXSFN), then perform step 11, if If the paging time (PO) is greater than or equal to the maximum value (MAXSFN), then step 12 is performed;

Step 11: Record the paging time (PO) under the current value of n as PO _n , PO _n = Paging Occasion, and let p=n+1; n=n+1, jump to step 9 and continue to execute, p and n The automatic addition of 1 can be realized by using a counter, and steps 9, 10, and 11 constitute the second cycle in the process;

Step 12: Submit all calculated paging time (PO) values corresponding to each n value, PO ₀ , PO ₁ , PO ₂ , . . . , PO _p-1 , to the physical layer for selection, and end the procedure.

The same method can be used to realize the selection formula of paging time in TDD idle mode: PO={(IMSI div K)mod(DRX cycle length div PBP)}*PBP+n*DRX cycle length+Frame Offset , the FrameOffset item, which is more than the paging time selection formula in frequency division multiplexing idle mode, indicates the frame offset of the paging indication channel, and its value is given in the system message; the extra PBP item indicates paging The block period is equal to the repetition period of the paging indication channel (PICH) in the system information broadcast.

In order to better understand the technical implementation steps of the selection formula of the paging time in the frequency division duplex (FDD) idle mode of the present invention, the 7-digit decimal global mobile subscriber identifier IMSI is taken as an example for further description.

Example 1. Assume that the global mobile subscriber identifier IMSI=a ₁ a ₂ a ₃ ... a _m-1 a _m =1234567, is a 7-digit decimal number, that is, m=7, which bears the auxiliary function of the paging channel (PCH) The number of common control physical channels (SCCPCH) K=4, the discontinuous reception cycle length DRX cycle length=256, and the maximum value of the cell system frame number MAXSFN=4095. Then the paging time (Paging Occasion) that needs to be selected under frequency division multiplexing (FDD) idle mode, adopts the technical scheme that the present invention proposes to realize in the following steps:

Step 1: Input the Global Mobile Subscriber Identifier IMSI=1234567, K=4 is the number of the Secondary Common Control Physical Channel (SCCPCH) carrying the Paging Channel (PCH), the discontinuous reception cycle length DRXcycle length=256, the cell The maximum value of the system frame number MAXSFN = 4095;

Step 2: That is, assign an initial value to the local variable sum, which is the first digit 1 of the IMSI, and sum=1;

Step 3: sum=sum mod(DRX cycle length×K)=1mod(256×4)=1, that is, the local variable sum is equal to the remainder of sum=1 divided by (DRX cycle length)×K, DRX cycle length=256 , K=4;

Step 4: i=2, that is, assign an initial value of 2 to the loop variable i;

Step 5: Since the loop variable i=2 is less than the number 7 of the IMSI, execute Step 6;

Step 6: sum=(10×sum+a ₂ )mod(DRX cycle length×K)=12, that is, sum is equal to the remainder of (10×sum+a ₂ ) divided by (DRX cycle length×K), the first The loop variable i=i+1=3, since the loop variable i is less than the digit number 7 of the IMSI, the seventh step is executed, and the first loop operation is continued;

Step 7: sum=(10×sum+a ₃ )mod(DRX cycle length×K)=123 mod 1024=123, that is, sum is equal to (10×sum+a ₃ ) divided by (DRX cycle length×K) Remainder, the first loop variable i=i+1=4, since the loop variable i is still smaller than the digit 7 of the IMSI, the eighth step is executed, and the first loop operation is continued;

Step 8: sum=(10×sum+a ₄ )mod(DRX cycle length×K)=1234 mod 1024=210, that is, sum is equal to (10×sum+a ₄ ) divided by (DRX cycle length×K) The remainder, the first loop variable i=i+1=5, is still less than the digit 7 of the IMSI, so execute step 9 and continue to execute the first loop operation;

Step 9: sum=(10×sum+a ₅ )mod(DRX cycle length×K)=2105 mod 1024=57, that is, sum is equal to (10×sum+a ₅ ) divided by (DRX cycle length×K) For the remainder, the first loop variable i=i+1=6, since it is still less than the digit 7 of the IMSI, execute step 10 and continue to execute the first loop operation;

Step 10: sum=(10×sum+a ₆ )mod(DRX cycle length×K)=576 mod 1024=576, that is, sum is equal to (10×sum+a ₆ ) divided by (DRX cycle length×K) Remainder, the 1st loop variable i=i+1=7, because the 1st loop variable i is equal to the digit number 7 of the global mobile subscriber identifier IMSI, so execute the 11th step, continue to execute the 1st loop operation;

Step 11: sum=(10×sum+a ₇ ) mod(DRX cycle length×K)=5767 mod 1024=647, that is, sum is equal to the remainder of dividing (10×sum+a ₇ ) by (DRX cyclelength×K), Circulation variable i=i+1=8, because the 1st circulation variable i is greater than the digit number 7 of global mobile subscriber identifier IMSI, therefore execute the 12th step, jump out of the 1st circulation;

Step 12: sum=sum div K=647 div 4=161, that is, the local variable sum is equal to the integer part after sum is divided by K;

The 13th step: assign the initial value 0 to the 2nd cycle variable n, promptly n=0; The number p=0 of the paging moment of remembering having selected;

Step 14: Paging Occasion=sum+n×DRX cycle length=161;

Step 15: Since Paging Occasion=161 is less than the maximum value MAXSFN=4095 of the system frame number of the cell; therefore execute Step 16;

The 16th step: PO ₀ =161, p=n+1=1; n=n+1=1; Execute the 17th step (actually jump to the 14th step and execute);

Step 17: Repeat steps 14, 15, and 16 until the calculated PagingOccasion value is greater than or equal to the maximum value of the cell system frame number MAXSFN=4095, and jump out of the second loop.

We can calculate:

PO ₁ =417, p=n+1=2, n=n+1=2;

PO ₂ =673, p=n+1=3, n=n+1=3;

PO ₃ =929, p=n+1=4, n=n+1=4;

PO ₄ =1185, p=n+1=5, n=n+1=5;

PO ₅ =1441, p=n+1=6, n=n+1=6;

PO ₆ =1697, p=n+1=7, n=n+1=7;

PO ₇ =1953, p=n+1=8, n=n+1=8;

PO ₈ =2209, p=n+1=9, n=n+1=9;

PO ₉ =2465, p=n+1=10, n=n+1=10;

PO ₁₀ =2721, p=n+1=11, n=n+1=11;

PO ₁₁ =2977, p=n+1=12, n=n+1=12;

PO ₁₂ =3233, p=n+1=13, n=n+1=13;

PO ₁₃ =3489, p=n+1=14, n=n+1=14;

PO ₁₄ =3745, p=n+1=15, n=n+1=15;

PO ₁₅ =4001, p=n+1=16, n=n+1=16;

Because at this time, PO ₁₆ = 4257, which is greater than the cell system frame number MAXSFN = 4095, so jump out of the second cycle and perform step 18;

Step 18: return the calculated value of the paging occasion (Paging Occasion), there are 16 in total: PO ₀ =161, PO ₁ =417, PO ₂ =673, PO ₃ =929, PO ₄ =1185, PO ₅ =1441, PO ₆ =1697, PO ₇ =1953, PO ₈ =2209, PO ₉ =2465, PO ₁₀ =2721, PO ₁₁ =2977, PO ₁₂ =3233, PO ₁₃ =3489, PO ₁₄ =3745, PO ₁₅ =4001, Finish.

Also can realize paging indicator (PI: Paging Indicator) calculation formula: PI=(IMSIdiv 8192) mod Np, wherein IMSI is the global mobile subscriber identifier, under frequency division duplex (FDD) mode Np=(18,36 , 72, 144), represents the number of paging indicators in each frame, in time division duplex (TDD) mode, Np is the number of paging indicators for each paging block, and is determined by the paging indicators given in the system information Call indicator length L _PI , burst type (long or short infix) and paging indicator channel (PICH) repetition length to calculate (the 8192 and Np values in the formula are determined by the protocol)

The realization method of the present invention is tested in Huawei WCDMA mobile user terminal products, and obtains good results.

Claims (7)

1. a kind of realization method that mobile user terminal selects paging time under idle mode, is applied in frequency division multiplexing broadband code division multiple access mobile communication system, it is characterized in that comprising the following processing steps: A. Input parameters, including the global mobile subscriber identifier (IMSI) of m bits, the length of the discontinuous reception cycle, the number K of the secondary common control physical channel (SCCPCH) carrying the paging channel (PCH), and the cell system frame The maximum value (MAXSFN) of the number (SFN); B. a local variable sum is set, and the initial value of the local variable sum is assigned as the first digit value of the global mobile subscriber identifier (IMSI); C. Let the new local variable sum be equal to: the remainder of the original local variable sum (integer) divided by the discontinuous receiving cycle length (integer) of K times; D. Assign the initial value of the first loop variable i to 2; E. judge whether the value of the 1st loop variable i is less than or equal to the digit m of global mobile subscriber identity (IMSI), if then execute step F, if not then execute step G; F. Let the new local variable sum be equal to: the sum (integer) of the numerical value of the i-th position in the former local variable sum of 10 times and the global mobile subscriber identifier is divided by the remainder of the discontinuous reception cycle length (integer) of K times again, And let the first loop variable i automatically increase by 1, and return to step E to continue execution; G. Make the new local variable sum equal to: the integer part after dividing the original local variable sum (integer) by K (integer); H. The second loop variable n is set, and the initial value of n is assigned as 0, and p is used to represent the number of selected paging moments (PO), and p is set to 0; 1. Let the paging moment (PO) be equal to the sum of the present value of the local variable sum and the discontinuous reception cycle length of n times; J. Judging whether the paging time (PO) is less than the maximum value (MAXSFN) of the cell system frame number, if the paging time (PO) is less than the maximum value (MAXSFN), then perform step K, if the paging time (PO) is greater than or equal to the maximum value (MAXSFN), then execute step L; K. the paging moment (PO) under the current n value is recorded as PO _n , let p be equal to n+1 and allow n to automatically add 1 and then jump back to step I to execute; L. Submit all paging time (PO) values obtained through the above steps and corresponding to each value of n, PO ₀ , PO ₁ , PO ₂ , . . . , PO _p-1 . 2. A method for realizing a mobile user terminal selecting a paging time in an idle mode according to claim 1, characterized in that: the discontinuous reception cycle length in the step A is 8, 16, 32, 64, A number among 128, 256, and 512, and the maximum value of the cell system frame number (SFN) is 4095. 3. the realization method that a kind of mobile user terminal according to claim 1 selects paging time under idle mode, is characterized in that: the m global mobile subscriber identifier (IMSI) in the described step A is a decimal number, Expressed as: IMSI=a ₁ a ₂ ... a _m-1 a _m , a ₁ is the first digit, a _i is the i-th digit, 0≤a _i ≤9. 4. a kind of realization method that mobile user terminal selects the paging time under idle mode according to claim 1, is characterized in that: in described step A, when mobile user terminal does not have global mobile subscriber identity (IMSI) , use the default value: IMSI=0, and let the discontinuous reception cycle length be 2.56 seconds. 5. A method for realizing a mobile user terminal selecting a paging time in an idle mode according to claim 1, characterized in that: in the step F, a counter is used to automatically add 1 to the first loop variable i. 6. A method for implementing a mobile user terminal selecting a paging time in idle mode according to claim 1, characterized in that: in the step K, two counters are used to carry out the number p of the effective paging time respectively Automatically increment by 1 with the second loop variable n. 7. a kind of realization method that mobile user terminal selects paging time under idle mode according to claim 1, is characterized in that: also comprises the method for realizing calculating paging indication (PI), and paging indication (PI) is equal to : divide the integer part after dividing 8192 by m global mobile subscriber identifier (IMSI) and then divide by the remainder of integer Np, Np is the number of paging indicators in each frame, and Np under the frequency division multiplexing mode is taken as One of 18, 36, 72, 144.