CN1361606A - Upward acceptance controlling method in wideband CDMA system - Google Patents

Abstract

The upstream acceptance controlling method in wideband CDMA system is that in a base station controller, calling service load increment is predicted and the lower acceptance threshold is regulated dynamically by changing calling proportion, and determining whether to perform acceptance control on the basis of measuring load in station (Node B). By means of the said method, non-linear characteristic of predicting service load increment in original high speed data is corrected, and the prediction of calling service load increment becomes ever more accurate. Accepting various services as far as possible while ensuring system stability can raise the operation efficiency of the system.

Description

Up-admission control method in a kind of broadband CDMA system

The invention belongs to 3-G (Generation Three mobile communication system)---Wideband Code Division Multiple Access (WCDMA) (WCDMA) field specifically, relates to the duty control method of WCDMA system.

Mobile communication development recently is very rapid, become a very important part among the human lives between a few years, under the promotion of Internet fast development, people have greatly promoted the development of 3-G (Generation Three mobile communication system) (IMT-2000) to craving for of mobile Internet simultaneously.The WCDMA technology is the mainstream technology of 3-G (Generation Three mobile communication system), the 3GPP of 3-G (Generation Three mobile communication system) standardization body in March, 99 by and the wireless interface technology standard of having issued Release 99 ' version.But 3GPP does not work out unified standard to the acceptance controlling method of WCDMA system as yet.

3-G (Generation Three mobile communication system) is that loaded service is different with the main distinction of second-generation system, and second-generation system is mainly based on voice service, and power system capacity is weighed with the number of channel or Ireland.Third generation system then is the multimedia service that voice service and Packet data service are mixed, and mainly weighs the capacity of system with throughput or power, and supports the high speed data transfer up to 2Mbps.In IMT--2000,, carrying out usually it being divided into four major types when QoS analyzes: conversational service (in real time), interactive service (non real-time), data streaming service (in real time) and backstage business (non real-time) according to the attribute of miscellaneous service and application.It is speech that the typical case of conversational service uses, and it is the WWW visit that the typical case of interactive service uses, and it is video flowing, FTP etc. that the typical case of dataflow-style business uses, and it is E-mail that the typical case of background type service uses.

In the WCDMA system,, when making a call the request wireless access, the user must admit control because the wireless link capacity of system is limited.The prerequisite of accurately admitting control is accurately to estimate on the basis of cell load, and the load increment that causes after also will inserting call business (comprising new call business and switch call business) is predicted accurately.Admittance is controlled accurately, just can admit more user or business under the prerequisite that system loading allows, thereby can keep the lower percent of call lost and cutting off rate, reaches higher service quality.

At present, the computing formula of predictive call traffic load increment is based on throughput.Specifically with reference to the works of people such as the Harri Holma of Nokia Telecommunications with reference to the 3GPP protocol specification---" WCDMA of UMTS---wireless access of 3G (Third Generation) Moblie ", the document is the up-to-date works of WCDMA paper that publish, comprehensive in 2000, be unique best book in the industry, combine the development of world WCDMA state-of-the-art technology in the book about UMTS WCDMA.Because the WCDMA technology do not have full maturity, standard also is among the modification and perfection, and system's control technology development lags behind especially, and third generation bit rate business is not also provided ripe, practical and well predicts the method for traffic load increment.Existing predictive call traffic load increment formula is

The relation of load increment Δ η and information source speed R is non-linear, it is inaccurate adopting the load increment of this formula predictive call business under the situation of bit rate, the power system capacity that obtains with this formula exceeds 2Mbps, cause the false judgment of admitting control easily, cause the out of control of system's control.The maximum actual active volume of a common sub-district just about 2Mbps, should not admitted more business again, otherwise the interference of system is too big, can't guarantee communication quality, even causes the out of control and collapse of system.

When the objective of the invention is to propose a kind of high bitrate data service request and inserting, the linear prediction of traffic load increment and dynamically adjust low threshold η according to the switch call ratio _Th2Up-admission control method.

The up-admission control method that the present invention proposes may further comprise the steps:

1) from the QoS of call business, extracts professional information source speed R, required signal-to-noise ratio Eb/No value and priority level;

2) with the load increment of R and Eb/No value substitution (1) formula predictive call business: ${\mathrm{\Δ\η}}_{\mathrm{UL}}=(1-e^{\frac{-\mathrm{\βR}}{{10}^{(1-\mathrm{\α\βR})}}})\mathrm{\υ}-----\left(1\right)$

(1) in the formula

, υ during speech=0.67, υ during data=1;

3) account for the ratio γ of total calling by statistics switch call in nearest 50 milliseconds, by Δ γ=0.6 γ calculated capacity reserved value Δ γ;

4) by η _Th2=η _Th1-Δ γ calculates the threshold value η of low priority traffice _Th2

5) the current uplink load η of taking-up service access sub-district from the load statistical form _UL

6) when call load incremental forecasting value Δ η and at present load η satisfy η+Δ η≤η _ThThe time, admit and call out, return the admittance signaling to RRC.Otherwise exclude, get back to the 1st) the step wait arrival of calling next time.Priority difference according to business is divided into two threshold value η _Th1And η _Th2(η _Th1＞η _Th2), therefore can be divided into following 2 steps again:

(1) when calling is high-priority call (as switch call or urgent call etc.), and η+Δ η≤η is arranged _Th1The time, admit and call out, return the admittance calling signaling to RRC, then carry out the 7th) step;

If as η+Δ η＞η _Th1The time, the access request of refusal high-priority call, RRC excludes calling by signaling, gets back to the 1st) step;

(2) when calling be normal priority (non-switch call or non-emergency call etc.) η+Δ η≤η _Th2The time, admit newly and call out, return the admittance signaling to RRC, then carry out the 7th) step;

If as general calling and η+Δ η＞η _Th2The time, exclude new calling, get back to the 1st) step;

7) start sign indicating number resource allocation subprocess;

8) change systematic code resource and load condition table.The present invention is further illustrated below in conjunction with accompanying drawing:

Fig. 1 is based on prior art load increment anticipation function curve chart; Fig. 2 is the flow chart of the inventive method; Fig. 3 is based on the new load increment anticipation function curve chart of the inventive method;

Fig. 1 is based on prior art load increment predictor formula function curve diagram; Functional relation is seen formula (2). $\mathrm{\Δ\η}=\frac{1}{1+\frac{W_c}{\mathrm{\α}\·E_b/N_o\·R}}-----\left(2\right)$

(2) in the formula: α is the voice activation factor, and the voice service unification gets 0.67, and the data service unification gets 1.0; Wc represents spreading rate, is a constant, equals 3.84Mcps; Eb/No is professional desired signal to noise ratio; R is the source bits speed of call business.When only considering data service (α=1), under different signal to noise ratios required, the relation curve of information source speed R and load increment Δ η was seen Fig. 1.

As seen find out that from Fig. 1 the relation of load increment Δ η and information source speed R is non-linear.When signal to noise ratio Eb/No=5dB commonly used, when peak load of access is the user of 2Mbps, its load increment only is 62%, should very load near 100% of sub-district this moment, obviously, the load increment of this formula predictive call business is incorrect in this case, causes the false judgment of admitting control easily.For example, it is unloaded that system begins, and corresponding load is η=0%, and a speed for the 2Mbps call business carries out the load increment prediction, is obtained predicted value Δ η=62%, less than the threshold value 75% of load, makes admission processing.After this, can also admit load-factor is that 13% normal priority is called out, or to admit load-factor be 33% high-priority call.Obviously, this is irrational, because the maximum actual active volume of a sub-district is just about 2Mbps, should not admit more business again, otherwise the interference of system is too big, can't guarantees communication quality, even cause system out of control and the collapse, that is to say, adopt formula (2) when high speed business inserts, can't admit control accurately, thereby the contradiction of system's operation stability and the percent of call lost can't solve higher load the time.

Fig. 2 is the flow chart of the inventive method; In the flow chart of Fig. 2, at the situation of call business priority, be divided into two thresholdings of height when judging the system loading thresholding: for switching the service call and the high-priority call of coming from other sub-district, decision threshold is established highlyer; For the lower new calling of priority, then decision threshold is established lowlyer.The difference of these two thresholdings is exactly that capacity is reserved, and uses for soft handover to guarantee to leave 20% to 30% capacity.

Threshold judgement frame among Fig. 2 is divided into high and low two thresholdings: be respectively η at the situation of call business priority when judging the system loading thresholding _Th1And η _Th2, η here _Th1＞η _Th2, the difference of these two load door limit values is exactly the capacity resource for handoff reservation.η for example _Th1=95%, η _Th2The handoff reservation capacity resource was exactly 20% in=75% o'clock.Here η _Th1Correspond to the upper limit load value that guarantees system stable operation; Second lower threshold value η _Th2Be dynamic, decide, that is to say, during the shared large percentage of switch call, η according to switching the statistical value that the number of calls accounts for total number of calls ratio in nearest a period of time _Th2If low, there are enough resources to realize grand diversity when switching with assurance, guarantee that simultaneously direct-cut operation has lower cutting off rate; When switch call accounts for the ratio of total calling when low, with η _Th2If high,,, improve operational efficiency or the operational efficiency benefit and the service quality of system to reduce the percent of call lost in order to avoid cross the new calling of multiple rejections normal priority.In a word, surpass η at load _Th2The time have only switching to wait the calling of high priority just may to be admitted, load is higher than η _Th1The time refuse all call requests, keep certain load allowance to guarantee system stable operation.

After adopting the new up-admission control method of the present invention's proposition, the nonlinear characteristic of prediction traffic load increment when having revised original high-speed data, prediction to the call business load increment is more accurate, under the prerequisite that guarantees system stable operation, admit miscellaneous service as much as possible, improved the efficient of system, reduce the percent of call lost and cutting off rate, improved service quality and economic benefit.Adopt the admittance control thresholding of dynamically adjusting low priority, further fully admit the user of normal priority, make the utilance of system higher, the percent of call lost and cutting off rate are lower.Fig. 3 is based on new load increment predictor formula function curve diagram.In order when calling out, accurately to predict the load increment of high-speed data service, overcome the non-linear of prediction, must look for another way, adopt new prediction and calculation formula.Formula (1) is a kind of predictor formula of basic retention wire sexual intercourse in the service rate scope, can predict accurately the load increment that high speed business is called out.Calling comprises calling that UE initiates from idle condition, be in and increase the calling that professional calling, switch call and cable network side are come the connection newly, the qos parameter that the high-rise radio resource manager (RRM) of radio network controller (RNC) obtains calling out from the RRC signaling, from qos parameter, can obtain professional type (speech or data), service rate, error rate requirement (signal to noise ratio Eb/No requirement) and priority, thus the load increment Δ η of predictive call.Under the situation that accurately the judgement system loads at present, can carry out correct admittance control.When admitting control,, when judging the system loading thresholding, be divided into two thresholding η of height at the situation of call business priority _Th1And η _Th2(η _Th1＞η _Th2), the difference of these two thresholdings is exactly that capacity is reserved, and uses for soft handover, and lower cutting off rate is arranged when guaranteeing direct-cut operation simultaneously.Switch call and high-priority call and η _Th1Correspondence is fixed, and is benchmark with the system stable operation; The new calling and the η of low priority _Th2Correspondence, thresholding are variable, decide according to switching the statistical value that the number of calls accounts for total number of calls ratio in nearest a period of time, that is to say, when switch call accounts for the ratio of total calling when low, with η _Th2If high,,, improve the operational efficiency (benefit) and the service quality of system to reduce the percent of call lost in order to avoid cross the new calling of multiple rejections normal priority.

New load increment predictor formula is seen (1) formula, and Fig. 3 is the curve chart of doing when only considering data service (υ=1).The software feature of power system capacity as can see from Figure 3, there was different capacity in system when promptly different Eb/No required.

Formula (1) is linear in practical ranges to the prediction of call business load increment basically, consider that the 5MHz bandwidth will reach the information source speed of 2Mbps when 1/2 rate coding, 2Mbps will add protocol header at SDU in each data block during to PDU, and the speed of carrying during to physical channel will be greater than the data rate of 2Mbps.In fact, up data rate maximum can reach 2.3Mbps when the physical channel bearing capacity is calculated, low slightly when descending, can reach about 2.2Mbps, and the load of correspondence 100% when heap(ed) capacity, when different signal to noise ratio Eb/No requires different power system capacities is arranged, this is the distinctive soft capacity characteristic of WCDMA system; Under the definite condition of the Radio Transmission Technology (RTT) of system, signal to noise ratio Eb/No requires high more, promptly requires the error rate low more, and power system capacity is just low more, otherwise power system capacity is just high.

In order to predict the load increment of call business in the WCDMA system more accurately, and dynamically adjust the admittance thresholding of general low priority traffice, overcome the nonlinear problem of original method, lower call loss (obstruction) rate is arranged under the prerequisite of system stability, adopt dynamic low threshold η _Th2Method can overcome the contradiction of the low percent of call lost and low cutting off rate, improved resource utilization ratio and service quality.

In sum, have only load increment to carry out linear prediction, could carry out the accurate control of admitting, reach system high efficiency, aim of stable operation call business.Dynamically adjust low threshold η with linear prediction call business load increment with according to switching proportion _Th2Method combine and admit control, can solve the contradiction of system's operation stability and the percent of call lost when the higher load access service.

The invention solves the linear measure problem of predictive call traffic load increment, be used for the network design and the network operation of WCDMA system, can reach high speed call business load increment is estimated accurately, make and admit control easily, network operation efficient height, the percent of call lost and cutting off rate reduce.Core of the present invention is the linear prediction of traffic load increment and dynamically adjusts low threshold η according to the switch call ratio _Th2The acceptance controlling method that combines, range of application of the present invention is not limited to the WCDMA field.

Claims (5)

1, a kind of method of up-admission control in broadband CDMA system is characterized in that may further comprise the steps:

Step 1: from the QoS of call business, extract parameters such as professional information source speed R, required signal-to-noise ratio Eb/No value and priority level;

Step 2: the load increment that utilizes formula predictive call business;

Step 3: account for the ratio γ of total calling, calculated capacity reserved value Δ γ by statistics switch call in nearest 50 milliseconds;

Step 4: the threshold value η that calculates low priority traffice _Th2

Step 5: the current uplink load η that from the load statistical form, takes out the service access sub-district _UL

Step 6: when the call load incremental forecasting value Δ η and the η that loads at present satisfy η+Δ η≤η _ThThe time, admit and call out, return the admittance signaling to radio resource controller: otherwise exclude, get back to the 1st) the step wait arrival of calling next time;

Step 7: start sign indicating number resource allocation subprocess;

Step 8: change systematic code resource and load condition table.

2, the acceptance controlling method in the broadband CDMA system in the WCDMA according to claim 1 system, it is characterized in that: the load increment of predictive call business calculates with following formula in the described step 2: ${\mathrm{\Δ\η}}_{\mathrm{UL}}=(1-e^{\frac{-\mathrm{\βR}}{{10}^{(1-\mathrm{\α\βR})}}})\mathrm{\υ}-----\left(1\right)$

In the formula

, for speech, get υ=0.67, for data, get υ=1.

3, the acceptance controlling method in the broadband CDMA system in the WCDMA according to claim 1 system, it is characterized in that: the admittance in the described step 6 is called out and is divided into following steps:

At first: when calling is high-priority call (as switch call or urgent call etc.), and η+Δ η≤η is arranged _Th1The time, admit and call out, return the admittance calling signaling to RRC, then carry out step 7;

If as η+Δ η＞η _Th1The time, the access request of refusal high-priority call, RRC excludes calling by signaling, gets back to step 1;

Secondly: when calling is normal priority (non-switch call or non-emergency call etc.) η+Δ η≤η _Th2The time, admit newly and call out, return the admittance signaling to RRC, then carry out step 7;

If as general calling and η+Δ η＞η _Th2The time, exclude new calling, get back to step 1.

4, the acceptance controlling method in the broadband CDMA system in the WCDMA according to claim 1 system is characterized in that: the ratio γ calculated capacity reserved value Δ γ that accounts for total calling by statistics switch call in nearest 50 milliseconds in the described step 3 calculates with following formula: Δ γ=0.6 γ.

5, the acceptance controlling method in the broadband CDMA system in the WCDMA according to claim 1 system is characterized in that: the admittance threshold value η that calculates low priority traffice in the described step 4 _Th2Calculate by following formula: η _Th2=η _Th1-Δ γ.

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