CN1158798C - Reverse permission control method - Google Patents

Abstract

The present invention relates to a reverse permission control method. The present invention has the technical scheme that a WCDMA system is a self-interference system, and the capacitance of the WCDMA system is limited by the interference received by a current subzone; in the reverse permission control method of a system, the situation that the interference increases after a user is permitted by a system is predicted at first; whether the user is permitted or not is decided according to whether the increased interference exceeds a threshold value allowed by a system or not. In the present invention, combined with the characteristics of the WCDMA system, the reverse permission control method is provided; the reverse permission control method is divided into two parts; a first part is a simple and practical prediction method for users of small rate (chiefly referring to speech); besides, indicated by a simulation result, the reverse permission control method accurately predicts the reverse interference of the system within a certain range; a second part is a permission determining method.

Description

A kind of reverse admission control method

Technical field

The present invention relates to the network mobile communication system, refer in particular to the reverse admission control method in a kind of wide band CDMA radio mobile communication system.

Background technology

The network mobile communication system is obtaining application more and more widely in the whole world, its communication standard also is diversified, more typically there is time-division communication (TDMA) to divide communicate by letter (CDMA) with sign indicating number, because cdma system is a kind of Wideband Code Division Multiple Access (WCDMA) communication system, it is as one of three big air-interface standards of current 3-G (Generation Three mobile communication system), advanced technology, the influence wide, extremely bright future is arranged.WCDMA is a kind of communication system of CDMA standard, and cdma communication system and other communication system have tangible different, and it is a self-interference system.The load of system is that the interference size by current system is determined that the interference of system is caused by the transmitting power of user in the system.After the user in the system surpasses some, can cause the phenomenon that each user power of system is obviously soaring, cause system load to be risen significantly at short notice, make system crash.Therefore, need control the load of system.

In the existing reverse admission control technique,, only be to judge whether the new requested service of access according to the reverse load value of current system and the service feature of request access because reverse load prediction more complicated does not often give a forecast to reverse load.What adopt in fairly simple, a lot of cdma system of this method all is this method.Its shortcoming also is clearly, mainly contains:

1, only being to do simple estimation by the reverse load value and the current new requested service feature of current measurement, is not to calculate system reverse load after the access by certain prediction algorithm, will inevitably cause the error estimated too big.

2, in order to guarantee the stability of system, reverse load is strict with and is not allowed to surpass certain threshold value, because the error of estimating is too big, the setting of the reverse load thresholding of access control is just required the comparison height.In general, also just many in order to guarantee the stable of system to the surplus that this threshold value is vacated, cause having sacrificed power system capacity like this.

The admittance control method that another is commonly used need be known the information in a large amount of current area when carrying out backward prediction, these information comprise the speed, business need, voice activation of all connection users in the reverse load value, sub-district of current system or the like.The defective of this access Forecasting Methodology has:

1, the information that need provide is too many, in the WCDMA system even can't provide desired definite information.

2, Forecasting Methodology complexity, the time that spends aspect prediction is too many, and it is too many to take resource.

3, in Forecasting Methodology, usually need all business information in the sub-district are carried out accumulation process.Because the complexity of real system, the information that obtains has error, can cause adding up of error after the business information of a plurality of connections adds up, and causes last resulting predicted value usually inaccurate like this.

Summary of the invention

The objective of the invention is: adopt the reverse load prediction, judge the access of new business according to its predicted value, it is not accurate enough and take the shortcoming of power system capacity to solve the accuracy of load estimation in the prior art.

Technical scheme of the present invention is: the wide band CDMA radio mobile communication system adopts reverse load to predict to the new business access, and according to prediction value decision new business access.According to the thermal noise power value, current reverse total received power value, the desired Carrier interference ratio parameter value of new business, the total oppositely received power value the when predictor formula that utilization provides calculates access.Total oppositely when access allows the new business access when received power value is than the high 6-10dB of thermal noise power.

Description of drawings

In order in more detail the principle of the invention to be described, describe as follows below in conjunction with accompanying drawing:

Fig. 1 is the reverse admittance control method flow chart of the present invention;

Fig. 2 reads sub-district reverse load flow chart for the reverse access of the present invention;

Fig. 3 is a network system traffic diagram of the present invention;

Fig. 4 is the imitative value of the present invention cell pattern figure;

Fig. 5 is the simulation curve figure when in the sub-district of the present invention 20 voice users being set;

Fig. 6 is the simulation curve figure when in the sub-district of the present invention 30 voice users being set;

Fig. 7 is the simulation curve figure when in the sub-district of the present invention 40 voice users being set;

Fig. 8 is the simulation curve figure when in the sub-district of the present invention 50 voice users being set;

Fig. 9 is the simulation curve figure when in the sub-district of the present invention 60 voice users being set.

Embodiment

See also Fig. 1, Fig. 2, Fig. 1 is the reverse admittance control method flow chart of the present invention, as can be seen, when receiving reverse access control request, system call reverse load prediction and calculation formula procedure.This reverse load predictor formula is derived like this: should satisfy when n user arranged in the sub-district:

$\mathrm{RTWP}\left(n\right)=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{P}_i+C----\left(1\right)$

Wherein: RTWP is the bearing power value in the bandwidth of accepting in the current area altogether, the prediction in fact just big or small to this value to the prediction of reverse load; P _iI the user's who receives for the base station power; C is that background noise adds the peripheral cell interference.

Before the nth user inserts:

$\mathrm{RTWP}(n-1)=\underset{i=1}{\overset{n-1}{\mathrm{\Σ}}}{P}_i+C----\left(2\right)$

Wherein: the reverse load value that the sub-district recorded when RTWP (n-1) was n-1 user; Received the sub-district when Pi was n-1 user from i (i=1 ..., n-1) individual user's power; C is that many area interference add thermal noise.

Again as can be known:

$\frac{P_i}{\mathrm{RTWP}(n-1)-P_i}={\mathrm{CIR}}_i----\left(3\right)$

Wherein: CIRi is the required chip energy interference ratio of this user.

Can know by inference by (3):

$P_i=\frac{{\mathrm{CIR}}_i\·\mathrm{RTWP}(n-1)}{1+{\mathrm{CIR}}_i}----\left(4\right)$

Substitution (2) formula gets:

∴ $\mathrm{RTWP}(n-1)=\frac{C}{1-\underset{i=1}{\overset{n-1}{\mathrm{\Σ}}}\frac{{\mathrm{CIR}}_i}{1+{\mathrm{CIR}}_i}}----\left(5\right)$

After the nth user inserts,

$\mathrm{RTWP}\left(n\right)=\underset{i=-1}{\overset{n}{\mathrm{\Σ}}}{P_i}^{\′}+C----\left(6\right)$

Wherein: the uplink load values that the sub-district received when RTWP (n) was n user; Pi ' sub-district when n user receive from i (i=1 ..., n-1) individual user's power; C is that many area interference add thermal noise.

In like manner, can release:

$\mathrm{RTWP}\left(n\right)=\frac{C}{1-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{{\mathrm{CIR}}_i}{{\mathrm{CIR}}_i}}----\left(7\right)$

Simultaneous (5), (7), RTWP (n-1), the RTWP (n) that the NodeB place records before and after inserting by the nth user and the CIRn value of nth user's correspondence can be tried to achieve the C value.

$C=\frac{\frac{{\mathrm{<figure-callout\; id="1"\; label="CIR\; n"\; filenames="C0112252700132.png"\; state="\{\{state\}\}">CIR</figure-callout>}}_n}{1+{\mathrm{<figure-callout\; id="1"\; label="CIR\; n"\; filenames="C0112252700132.png"\; state="\{\{state\}\}">CIR</figure-callout>}}_n}}{\frac{1}{\mathrm{RTWP}(n-1)}-\frac{1}{\mathrm{RTWP}\left(n\right)}}----\left(8\right)$

When n+1 user asks to insert,, and can predict that according to the C value that formula (8) is obtained the RTWP value after the access is according to the general expression of RTWP:

$\mathrm{RTWP}(n+1)=\frac{C}{\frac{C}{\mathrm{RTWP}\left(n\right)}-\frac{{\mathrm{CIR}}_{n+1}}{1+{\mathrm{CIR}}_{n+1}}}----\left(9\right)$

By above analysis as can be known the C value calculate by formula (8) because the problems of calculating such as error can cause the calculating of C value inaccurate.

We know that the C value is that the peripheral cell interference adds the thermal noise power sum, and its value is receiving between RTWP value and the thermal noise value.

Under two kinds of extreme cases:

1, every on every side community user number is 0, and the interference that center cell receives other sub-district is 0, and at this moment, the C value is exactly thermal noise N ₀Value.

2, the center cell number of users is 0, and the RTWP value of center cell just is the C value.

We are heat-obtaining noise N ₀Predict RTWP (n+1) value for the C value, can guarantee like this to predict that the RTWP (n+1) that obtains is higher limit.Predictor formula is modified to:

$\mathrm{RTWP}(n+1)==\frac{N0\&CenterDot;W}{\frac{N0\&CenterDot;W}{\mathrm{RTWP}\left(n\right)}-\frac{{\mathrm{CIR}}_{n+1}}{1+{\mathrm{CIR}}_{n+1}}}----\left(10\right)$

Wherein: NOW is the power of thermal noise, can set up in the sub-district or sub-district when very idle (peripheral cell user and center cell number of users are 0 situation), and the reverse total received power of system is worth in this sub-district by measuring; RTWP (n) is the also inaccurate fashionable total oppositely received power value of current n+1 user; CIRn+1 is the chip energy interference ratio of n+1 customer requirements of current request access.

The second portion of access algorithm is that access control judges that principle is as follows:

The thresholding that reverse total power value that formula (10) prediction is come out and access allow is compared, and greater than the thresholding that allows, then access should business as this value.Less than the access thresholding, then refuse this business access (seeing also Fig. 1) as predicted value.

At first we will file a request to reverse access control, enter load predicting method, are worth judgement when whether the reverse load of predicting surpasses the access control threshold value; As allow to enter, then read the thermal noise power value, read the current area reverse load then, and read new requested service characteristic value.According to reverse load value after load estimation formula and the above-mentioned value calculating new business access, return the load estimation value then.We set a simulated environment according to this theory, as shown in Figure 1.

Cell pattern is provided with 3 layers, 19 sub-districts altogether for the base station spacing is 1 kilometer a hexagonal macrocell model.Cell pattern is seen accompanying drawing 4.1 middle sub-district is called center cell, and other 18 sub-districts are called peripheral cell, and all simulation results are as the criterion with the result of center cell.Antenna is positioned at the center of sub-district, and antenna model is the omnidirectional antenna model of 10dBi for gain.Do not consider soft changing state, the user selects the sub-district according to path loss fully.

Simulation parameter is provided with: the WCDMA spreading rate is 3.84M.What adopt in emulation is that voice user's speed is 8kbps.User's Eb/IO desired value is set to 6.8dB.Thermal noise power is set to-103.13dBm.

According to the CDMA theory, be no more than when the reverse interference value that receives under the situation of 6～10dB of thermal noise power, can think that system can stable operation.When checking prediction algorithm emulation, the prediction algorithm accuracy of analogue system under can the situation of stable operation only, the total interference that promptly receives is no more than under the situation of thermal noise 10dB prediction algorithm is verified.In the following situation that is provided with of emulation, the result who measures as shown in Figure 5.

Peripheral cell is provided with 20 voice users, the situation that the center cell number of users constantly adds up.Simulation result is seen accompanying drawing 5.

Peripheral cell is provided with 30 voice users, the situation that the center cell number of users constantly adds up.Simulation result is seen accompanying drawing 6.

Peripheral cell is provided with 40 voice users, the situation that the center cell number of users constantly adds up.Simulation result is seen accompanying drawing 7.

Peripheral cell is provided with 50 voice users, the situation that the center cell number of users constantly adds up.Simulation result is seen accompanying drawing 8.

Peripheral cell is provided with 60 voice users, the situation that the center cell number of users constantly adds up.Simulation result is seen accompanying drawing 9.

Abscissa unit among each figure is the number of users of center cell access, and ordinate unit is dBm.The curve in bottom among the figure is the thermal noise NO performance number that center cell receives; The RTWP value that middle curve receives for the center cell that obtains with the predictor formula prediction; Top curve is for obtaining the RTWP value that the practical center sub-district receives in emulation.Curve relatively and top curve, as can be seen, for the voice user, the value that prediction obtains and the value difference of actual emulation are not very little, and predictor formula can well be predicted the reverse load situation after new business inserts.Be that center cell receives RTWP value situation.

In sum, load predicting method of the present invention, requiring provides few parameter, and it only is a thermal noise power, current reverse load value, request access new business feature.Reached purpose of the present invention thus.

Claims (3)

1, a kind of reverse admittance control method is characterized in that: the wide band CDMA radio mobile communication system is to the prediction of new business access employing reverse load with according to prediction value decision new business access.According to predictor formula:

$\mathrm{RTWP}(n+1)=\frac{N0\&CenterDot;W}{\frac{N0\&CenterDot;W}{\mathrm{RTWP}\left(n\right)}-\frac{{\mathrm{CIR}}_{n+1}}{1+{\mathrm{CIR}}_{n+1}}}$

, with required thermal noise power (NOW), current reverse total received power (RTWP (n)), the desired chip energy interference ratio of new business (CIR _N+1), the total oppositely received power value RTWP (n+1) when the substitution predictor formula calculates n+1 user's access).As RTWP (n+1) during than the high 6-10dB of thermal noise power, described n+1 user is allowed to access.

2, reverse admittance control method as claimed in claim 1 is characterized in that: thermal noise power can be set up in the sub-district or sub-district when very idle, and the reverse total received power of system is worth in this sub-district by measuring.

3, reverse admittance control method as claimed in claim 1 is characterized in that: current reverse total received power is meant the current reverse total received power of measuring the sub-district.

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