CN1365203A - Calling-on control method in CDMA communicatino system - Google Patents

Abstract

The present invention is a kind of call admittance control method in CDMA communication system. For some call request, the present ivnention performs forward link and reverse link check and judges whether or not accept the call request based on if the call request exceeds some threshold value. If it exceeds, the call request is rejected, and if not, accepted. Therefore, the call admittance control method of the present invention can adapt the true operation environment of the system accurately and has high efficiency.

Description

The method of Admission Control in a kind of cdma communication system

The present invention relates to the method for Admission Control in the cdma communication system.

In present cdma communication system, the method for two kinds of common Admission Control is arranged, a kind of is the forward-link capacity control method of call number, a kind of is the forward direction overload controlling method.For the forward-link capacity control method of call number, this method is according to the serviced quantity control cell capacity of setting up calling in the sub-district just.According to this method,, obtain the threshold value of fixed service permission by experiment, i.e. call number if consider the influence of factors such as cell power output, communication environments.When the travelling carriage receipt of call of base station from the sub-district attempted request, this base station will be just serviced calling sum and call admission threshold ratio be in section.If call out sum less than the call admission threshold value, then distribute this calling, and if call out sum more than or equal to the call admission threshold value, then make this call attempt request enter queueing condition, or refuse this calling.In said method, because the communication environments difference between each sub-district, so the maximum call number difference that in different districts, can insert, the call admission threshold value is also different.And, because the phase mutual interference between each base station of forward direction, the customer call quantity that can serve in the sub-district is not absolute, it changes with the variation of peripheral base station transmitting power, therefore, with the foundation of judging as the cell call access control based on the call admission threshold value of call number, can not truly reflect the actual ability that can insert calling in base station.

In CDMA Cellular System, all there is the limit of a maximum forward direction transmission power that allows each base station.In other words, must divide equally from all forward service signals of base station at whole power that any one time allows, if the service link number increases and unrestricted when allowing the base station, a little less than then the forward signal power on every link becomes too the most at last, the zero defect that can not guarantee existing user receives, and signal quality constantly worsens once more.Therefore, for the forward direction overload controlling method, this method is utilized the overall forward power requirement of forward direction overload control base station according to the power budget of given base station power amplifier.This method adopts the scheme of " blindly blocking ", and in a single day the base station forward power has reached low threshold value, and for example 85%, even there is enough power to be adapted to given user's request, the request that new user sets up calling also gets clogged.And the operation that this method trends towards guarding makes available base station power utilize 2～3dB less, and does not have to take into full account the interference between each adjacent base station.

From the above mentioned, the common drawback of above-mentioned two kinds of methods is exactly the accurate real running environment of adaptive system of Admission Control of system, and efficient is not high.

At the problems referred to above, the purpose of this invention is to provide the real running environment of the accurate adaptive system of a kind of energy, the method for Admission Control in the higher cdma communication system of efficient.

For achieving the above object, the technical solution used in the present invention is: the method for Admission Control in a kind of cdma communication system, and this method may further comprise the steps: the receipt of call request of (1) base station; (2) the Admission Control unit carries out the reverse call access and judges, if oppositely access control allows this calling to enter, and execution in step (3) then, otherwise, execution in step (8); (3) the load detecting unit of base station calculates the indicated value of cell forward link load; (4) will the load indicated value of the forward link load that detecting unit calculates of the access control unit of base station is compared with forward direction access threshold value, if less than threshold value, and execution in step (5) then, otherwise, execution in step (8); (5) whether the inspection of Admission Control unit has an available idle extended code that meets request rate, if having, and execution in step (6) otherwise execution in step (8); (6) whether the inspection of call admission control unit has the baseband processing unit of a free time, if having, and execution in step (7) otherwise execution in step (8); (7) the call admission control unit is permitted the processing that this calling enters, and returns the pending next calls such as (1) of described step after disposing; (8) Call Control Unit is refused the processing operation of this calling, returns the pending next calls such as (1) of described step after disposing.

Above-mentioned forward direction access threshold value is: η S _Upp, wherein, η is for adjusting the factor, at type of service or priority and difference, and 0＜η≤1, S _UppBe the base station maximum transmission power.

The technical scheme that is adopted by the invention described above is as can be known: because that data service becomes in the cdma wireless communication system is professional widely, preceding reverse traffic is asymmetric, the forward direction load is usually much larger than reverse load, therefore, the present invention is for a call request, by the inspection of reverse link load and the inspection of forward link load, under loading the situation that all allows the calling access, preceding reverse link inserts this calling, make the accurate real running environment of adaptive system of method of Admission Control provided by the invention, efficient is higher.

The present invention is described in further detail below in conjunction with drawings and Examples.

Fig. 1 is the illustraton of model of a cell system of the present invention;

Fig. 2 is the illustraton of model of one 19 cell;

Fig. 3 is the flow chart of Admission Control of the present invention.

At first principle of the present invention is described by the present invention typical case environment of applications.

With reference to figure 1,2.Base station sub-system 112 is carried out radio communication by the travelling carriage 120a-120e of antenna 110 and five examples as can see from Figure 1, and base station sub-system 112 communicates by optical fiber or cable and mobile switching centre 114.Travelling carriage 120a-120e reports the total interference power that receives on the forward link that it records periodically, and base station sub-system 112 can also be estimated the distance of each travelling carriage 120a-120e apart from the base station according to the propagation delay of signal.

In the normal running of said system, travelling carriage 120a-120e and base station communicate, to make a call, to set up calling or the base station is sent or receive various expenses (overhead) message.Send in the measurement report message of base station at travelling carriage 120a-120e, can carry total interference power that travelling carriage 120a-120e receives, the system message of carrying total received power information that the base station sends according to each travelling carriage 120a-120e in the cell that receives, and, estimate the forward link load of this cell according to each travelling carriage 120a-120e of time-delay calculation distance to the base station.

Fig. 2 is the illustraton of model of one 19 cell.For cell shown in Figure 2, suppose that user i is controlled by base station 1, receive that interference signal is from J base station.Make user i be from the gross power that base station j receives

, and think to all j ≠ 1 o'clock,

The user should be always and the base station communication of receiving the signal strength signal intensity maximum.Now, suppose that a part of 1-β of the overall transmission power of arbitrary cells or sector gives steering signal, and public information (such as pseudo noise code initial vector or paging data) will reach all users arbitrarily.The part β that stays just locatees all k to base station oneself in this sub-district or the sector _uIndividual user.Like this, i user receives the part of transmitting power

, Ф wherein _iSatisfy condition,

The interference power that user i receives in the base station 1 adds average noise and (uses

Expression) be: $I_{0_{1i}}W=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{S}_{R_{\mathrm{ji}}}+N_{0}W$ This value is slightly higher than actual value, because

The very fraction β Ф of middle power _iShould do not included.The power of j the base station that user i receives

Equal the product of total transmitting power in j base station and logarithm normal distribution attenuation, for: $S_{R_{\mathrm{ji}}}=S_j\·d_{\mathrm{ji}}^{-m}{10}^{-{\mathrm{\ζ}}_{\mathrm{ji}}/10}$ d _JiBe the distance of j base station to i user, and ζ _JiBe corresponding lognormal component, average is 0, standard variance σ=8dB, and power selects m=4, with (2) formula substitution (1) formula, obtains: $I_{0_{1i}}W=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{S}_j\·d_{\mathrm{ji}}^{-m}{10}^{-{\mathrm{\ζ}}_{\mathrm{ji}}/10}+N_{0}W$

Usually, to compare with the total signal power of receiving from all base stations (signal that comprises all users) be insignificant to background noise (mainly being thermal noise).Because base station transmitting power is limited unlike the travelling carriage transmitter, so can in following formula, remove N ₀The W item.

Obtaining of the upper limit is all with maximum power S at this cell base station and all neighbor base stations _UppDuring emission, total interference power that the user mobile phone end records, that is: ${\left(I_{0_{1i}}W\right)}_{\mathrm{upp}}=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{S}_{\mathrm{upp}}\·d_{\mathrm{ji}}^{-m}{10}^{-{\mathrm{\ζ}}_{\mathrm{ji}}/10}$

All all relevant with the logarithm normal distribution variable with distance, its distribution is difficult to simple analysis.But this distribution can directly obtain with covering spy-Carlow (Monte Carlo) emulation.Suppose that a given user can only receive the transmitting power with base station in two concentric donuts of its sub-district, place, as shown in Figure 2.Like this, J=19, it has comprised given base station, 12 base stations in 6 base stations in first ring and second ring, variable

Relevant with i user's position, this user is that supposition is equally distributed in the space.Like this, this distribution will be the mean value of all positions in this sub-district, will disturb the ratio with maximum transmission power

As the normalization factor of forward direction interference, that is: ${\mathrm{\λ}}_d={\left(I_{0_{1i}}W\right)}_{\mathrm{upp}}/S_{\mathrm{upp}}$ $=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}{d}_{\mathrm{ji}}^{-m}{10}^{-{\mathrm{\ζ}}_{\mathrm{ji}}/10}.$ Disturb indicated value I at definite forward direction ₀W the time, suppose that in the communication process of reality total interference power that the user i of Target cell receives adds average noise and is

Right Make normalized, normalization factor λ arrives the relevant apart from d of base station with user i, then all users is taken statistics on average, obtains: $I_{0}W=\stackrel{\‾}{\left(I_{0_i}W\right)/{\mathrm{\λ}}_i}$ $=\frac{1}{K}(\underset{j=1}{\overset{K}{\mathrm{\Σ}}}\left(I_{0_i}W\right)/{\mathrm{\λ}}_i)$

Wherein, K is the number of users of having served in the sub-district.

Consider the influence of decline and bursty interference, in an observation window T, get N the measured value of putting, be used as forward direction interference indicated value I with the statistical average of these values ₀W, $I_{0}W=E_N{E}_K(\left(I_{0_i}W\right)/{\mathrm{\λ}}_i)$ $=\frac{1}{N}\frac{1}{K}\left(\underset{j=1}{\overset{N}{\mathrm{\Σ}}}(\underset{i=1}{\overset{K}{\mathrm{\Σ}}}\left(I_{0_i}W\right)/{\mathrm{\λ}}_i{)}_j\right)$

Because being the forward link that all travelling carriages report in the sub-district, this value receives the statistical average of disturbing, reflected the influence to this cell forward link of this cell base station and all peripheral cell base stations comparatively all sidedly, the judgment basis that is used as the forward direction load level is a very desirable selection.Determine the threshold value of Admission Control below.By formula Can obtain:

In ideal conditions, The upper limit obtain be

Obtain maximum

The time, just all base stations are all with maximum power S _UppEmission.Like this, definable η S _Upp(0＜η≤1) is forward direction access control thresholding, and η is for adjusting the factor, at type of service or priority and difference.When there was new service request a certain sub-district, elder generation disturbed indicated value I according to the forward direction of the interference calculation sub-district that travelling carriages all in the sub-district reports ₀W when this is worth greater than calling access thresholding, illustrates that the interference in the sub-district is very serious, not with access; Otherwise, access.Perhaps can when being in different thresholdings, the interference average that reports when mobile phone distribute different traffic data rate according to the different threshold values of definition.

Specifically, the present invention is achieved in that with reference to figure 3: at first, the base station receives a call request at step S1; The Admission Control unit carries out reverse Admission Control at step S2, if oppositely admission control algorithm allows this calling to enter, and execution in step S3 then, otherwise execution in step S8 does the processing of this calling of refusal; At step S3, the forward direction that the load detecting unit of base station calculates cell disturbs indicated value, and this value has identified the load condition of forward link; At step S4, the access control unit of the base station forward direction that detecting unit calculates of will loading disturbs indicated value to compare with forward direction access threshold value, if less than threshold value, and execution in step S5 then, otherwise execution in step S8 does the processing of this calling of refusal; The Admission Control unit checks at step S5 whether an available idle extended code that meets request rate is arranged, when not meeting the idle extended code of request rate at step S5 place, control unit execution in step S8 does the processing of this calling of refusal, when when step S5 has available idle extended code, the call admission control unit is checked the baseband processing unit whether a free time is arranged at step S6; When having in step S6 place that baseband processing unit is current all to be used, control unit execution in step S8 does the processing of this calling of refusal, when when step S6 has available baseband processing unit, the call admission control unit is permitted the processing that this calling enters at step S7, and return and begin the place, wait for the next call request.At step S8, control unit is handled the operation that refusal is called out, and also returns to begin the place, waits for that the next call request arrives.

Claims (2)

1, the method for Admission Control in a kind of cdma communication system, it is characterized in that: this method may further comprise the steps: the receipt of call request of (1) base station; (2) the Admission Control unit carries out the reverse call access and judges, if oppositely access control allows this calling to enter, and execution in step (3) then, otherwise, execution in step (8); (3) the load detecting unit of base station calculates the indicated value of cell forward link load; (4) will the load indicated value of the forward link load that detecting unit calculates of the access control unit of base station is compared with forward direction access threshold value, if less than threshold value, and execution in step (5) then, otherwise, execution in step (8); (5) whether the inspection of Admission Control unit has an available idle extended code that meets request rate, if having, and execution in step (6) otherwise execution in step (8); (6) whether the inspection of call admission control unit has the baseband processing unit of a free time, if having, and execution in step (7) otherwise execution in step (8); (7) the call admission control unit is permitted the processing that this calling enters, and returns the pending next calls such as (1) of described step after disposing; (8) Call Control Unit is refused the processing operation of this calling, returns the pending next calls such as (1) of described step after disposing.

2, the method for Admission Control in a kind of cdma communication system according to claim 1, it is characterized in that: described forward direction access threshold value is: η S _Upp,

Wherein, η is for adjusting the factor, at type of service or priority and difference, and 0＜η≤1, S _UppBe the base station maximum transmission power.

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