CN1159879C - A method for controlling call admission in code division multiple access mobile communication system - Google Patents

Abstract

The invention discloses a method for controlling call permission in a code division multiple access mobile communication system. The method predicts the interference power after a target cell and an adjacent cell access a new user, and according to the access threshold of interference and the call request The parameter calculates the highest service rate that the target cell can accommodate, so that the call admission control avoids the interference power exceeding the allowable range of the system due to the access of new users, increases the flexibility of the call admission control, and can ensure the stability of the system , Link communication quality under the premise of maximizing the use of cell capacity.

Description

The control method of call admission in a kind of CDMA mobile communication systems

Technical field

The present invention relates to the call permission control method in CDMA (code division multiple access) mobile communication system.

Technical background

In cdma system, channel is made of spreading code, each user uses the shared same radio band of different spreading codes, therefore, use at this communication unit under the situation of identical frequency band, most of communications of all communication units become interference source mutually, no matter which kind of spreading code the user uses in communication, by the total amount decision communication quality that disturbs.For this reason, in cdma system,, must suppress the quantity of interference source in order to guarantee communication quality.Usually, for interference volume is suppressed at below the fiducial value, just must limit the number of users that enlarges connection simultaneously.

One piece of " the Irish capacity of power control CDMA system " (IEEE Journal onSelected Areas in Communications by name, Vol.11, No.6, pp.892-900, in August, 1993) in the literary composition a kind of call permission control method is disclosed, in the method, pre-determine an interference level threshold value and the interference level observed surpasses this calling of refusal permission under the situation of this predetermined threshold when bid the time.

The NTT mobile radio communication company of Japan has proposed a kind of method of carrying out call admission control in CDMA mobile communication system, this method is calculated the blocking probability and the communication quality probability of malfunction of each base station at each place, base station, thereby can connect user's maximum quantity when adjusting each base station according to the result who calculates, when adjustment can connect user's maximum quantity, carry out call admission control.

Motorola Inc. has also proposed a kind of method that is used at the cdma system blocked call.It receives a call attempt request of being sent on the Target cell of cdma system; Calculate the Payload of this Target cell, this Payload is compared with a defined threshold,, then send a refuse information and refuse this call attempt request if this Payload surpasses defined threshold.

The shortcoming of above-mentioned prior art is, carry out call admission control with pre-determining an interference level threshold quantity method, can guarantee that blocking probability and communication failure probability are below permissible value, but because the time-varying characteristics of channel and wireless environment, any fixing configuration all is to calculate at probability distribution theory or the preceding actual measurement of configuration, so can not guarantee the flexibility in the practical application.Particularly cell load is less around, and wireless environment is preferably under the situation, though the actual capacity permission, can not the multiple access user.Simultaneously, in 3-G (Generation Three mobile communication system), the ratio regular meeting of data service is higher, and simultaneously, the service rate of request service changes can be bigger.In the cdma system of variable bit rate spread spectrum, the power of data service is relevant with its speed, service quality, and the data user that speed is high can produce the interference with respect to several times of voice users even tens times.So, call out control with the quantity of fixed access subscriber and no longer be fit to the communication system that voice-and-data is professional and deposit.And the access of data service can make the area interference grade rise, and the QoS of customer that this sub-district, adjacent cell have been inserted descends, and under the serious situation, even power control also is difficult to recover, causes the instability of system.

Summary of the invention

At the problem that above-mentioned prior art exists, the purpose of this invention is to provide the control method of call admission in a kind of effective CDMA mobile communication system.

For achieving the above object, the technical solution used in the present invention is: the control method of call admission in a kind of CDMA mobile communication systems, this method comprises: speech business access thresholding and data service access thresholding are set respectively in the base station, make the base station regularly receive the measurement report of the total interference power in sub-district, and use noise power N ₀Be recorded in the data storage after the normalization; And this method also comprises following operating procedure:

(1) inserts the call connection request of carrying information such as data rate, service quality;

(2) read the interference value of sub-district current in the buffer memory and the threshold value of professional access;

(3) whether judge interference value that above-mentioned steps (2) reads less than the access threshold value, if less than the access threshold value, execution in step (12), otherwise execution in step (4);

(4) N+1 user of prediction inserts the interference value of this sub-district, back;

(5) whether judge interference value that above-mentioned steps (4) obtains less than threshold value, if less than, execution in step (6), otherwise execution in step (9);

(6) from the data storage of this cell base station, read the interference prediction value of adjacent cell and the threshold value of professional access;

(7) N+1 user of prediction inserts the interference value of back adjacent cell;

(8) whether judge interference value that above-mentioned steps (7) obtains less than threshold value, if less than, execution in step (10), otherwise execution in step (9);

(9) judge whether N+1 the user's data that inserts is business datum, if, execution in step

Otherwise execution in step (12) (11);

(10) carry out call admission and handle, finish this then and call out access operation;

(11) carry out service negotiation and handle, finish this then and call out access operation;

(12) carry out call denial and handle, finish this then and call out access operation.

Above N+1 user of described prediction interference value of inserting this sub-district, back carry out according to following method: according to the data rate R that comprises in the call request message, the ratio E of bit energy and noise density _b/ N ₀Or can be converted into the signal to noise ratio SIR of bit energy and the ratio of noise density, with following formula calculate insert this speed ratio data service after, the interference value I of this sub-district ₀/ N ₀, respectively with subscript N and N+1 difference,

${(I_0/N_0)}_{N+1}\≥\frac{{(I_0/N_0)}_N}{1-\frac{1}{{\mathrm{\Γ}}_N+1}\·{(I_0/N_0)}_N}$ Wherein: ${\mathrm{\Γ}}_{N+1}=\frac{W/(R_{N+1}\·\mathrm{\α})}{{(E_b/N_0)}_{N+1}}$

W is an apread spectrum bandwidth, and a is an activity factor, for data service, and a=1.

Above N+1 user of described prediction interference value of inserting the back adjacent cell carry out according to following method: calculate the ratio of travelling carriage according to this district pilots intensity of moving table measuring and adjacent cell pilot frequency intensity apart from the wireless distances of adjacent cell base station and this cell base station, with transmitting power according to the travelling carriage of estimating, predictive call inserts the interference value of back adjacent cell, concrete grammar is: establishing this sub-district and adjacent cell base station is A and B, and travelling carriage is d to this cell base station and adjacent cell base station radio distance _AAnd d _B, make μ=(d _B/ d _A) ^-γ, wherein to get representative value be 4 to γ, use following formula calculate the user the A sub-district insert call out after, the interference value (I of the adjacent cell of prediction ₀/ N ₀) _B', ${\left(\frac{I_0}{N_0}\right)}_B^{\′}\≥{\left(\frac{I_0}{N_0}\right)}_B+\frac{\mathrm{\μ}}{{\mathrm{\Γ}}_{N+1}}\·{\left(\frac{I_0}{N_0}\right)}_A\·{\left(\frac{I_0}{N_0}\right)}_B$ Wherein: ${\mathrm{\Γ}}_{N+1}=\frac{W/R_{N+1}}{{(R_b/N_0)}_{N+1}}.$

Above the described call admission that carries out handle according to following step operation:

(1) the call admission control unit has judged whether idle orthogonal code, if having, and execution in step (2), otherwise execution in step (4);

(2) the call admission control unit judges whether the baseband processing unit of a free time, if having, and execution in step (3), otherwise execution in step (4);

(3) the call admission control unit is permitted the processing that this calling enters, and finishes this then and calls out access operation;

(4) control unit is handled the operation that refusal is called out, and finishes this then and calls out access operation.

Above the described service negotiation that carries out handle according to following step operation:

(1) the data service request inserts, and predicted interference is greater than threshold value;

(2) calculate this sub-district with following formula and can allow the maximum data rate R that inserts _Max1,

${\mathrm{\Γ}}_{N+1}=\frac{W/R_{\max 1}}{{(E_b/N_0)}_{N+1}}$

$T_d\≥\frac{{(I_0/N_0)}_N}{1-\frac{1}{{\mathrm{\Γ}}_N+1}\·{(I_0/N_0)}_N};$ Wherein, T _dBe data service access thresholding;

(3) calculate the maximum data transfer rate R that the Target cell that do not cause adjacent cell to surpass threshold value can insert with following formula _Max2,

${\mathrm{\Γ}}_{N+1}=\frac{W/R_{\max 2}}{{(E_b/N_0)}_{N+1}}$

$T_d\≥{\left(\frac{I_0}{N_0}\right)}_B+\frac{\mathrm{\μ}}{{\mathrm{\Γ}}_{N+1}}\·{\left(\frac{I_0}{N_0}\right)}_A\·{\left(\frac{I_0}{N_0}\right)}_B;$

(4) consult with min (R with the mobile subscriber _Max1, R _Max2) insert;

(5) judge whether negotiation is successful, if consult successfully, then with min (R _Max1, R _Max2) insert and call out, otherwise, call congestion.

Above the mobile station's initial transmit of described estimation carry out according to following method:

N+1 mobile station's initial transmit S _Send(dBm) be:

S _send(dBm)＝P _N(dBm)-Γ _N+1(dB)+P _dec(dB)

P _N(dBm) be N+1 the travelling carriage gross power that base station BS receives when not inserting, P _Dec(dB) N+1 the travelling carriage of estimating for the base station decayed to the backward channel of base station.

The technical scheme that adopts from the invention described above as can be seen, the present invention can reach the reason of goal of the invention and the invention has the advantages that the following aspects:

(1) in the cdma cellular mobile communication system, along with the access of community user, the interference of sub-district is nonlinear growth, and especially when data service inserted, this user's transmitting power can cause this sub-district and adjacent cell interference power to promote significantly.The present invention carries out call admission control according to real-time area interference grade, not according to concrete connection number of users, so can break away from the limitation of traditional permission control, the interference decision that receives according to the base station of current time could insert new user, has increased the flexibility of call admission control.And the present invention can maximally utilise cell capacity under the prerequisite that guarantees the stability of a system, link communication quality.

(2) the present invention can predict the interference power that Target cell and adjacent cell insert behind the new user, has avoided causing interference power to surpass the scope that system allows because of new user's access.

(3) the present invention is when the data service calls request, and the highest service rate that can hold according to the calculation of parameter Target cell of access thresholding that disturbs and call request provides the service requester maximum rate that a system can allow to insert.Therefore can provide the resource to greatest extent that can satisfy service quality to service requester.

(4) the present invention can be according to the level of interference of sub-district, the speed of user's requested service, service quality, mobile phone is determined the Initial Trans of mobile phone to the Radio Link loss of base station, so can approach actual value more than the definite of conventional mobile phone Initial Trans, has shortened the stable time.

Description of drawings

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

Fig. 1 is the schematic diagram of three sectorized cell systems;

Fig. 2 is to use the CDMA mobile communication system ideograph of the method for call admission control of the present invention;

Fig. 3 is the embodiment flow chart of call permission control method of the present invention;

Fig. 4 is the flow chart that carries out the embodiment of service negotiation of the present invention.

Embodiment

Before discussion enforcement of the present invention, at first the principle of foundation of the present invention is done elaborating.

Suppose to have in the single sub-district N user in conversation, then for one of them user, the base station BS receiver receives useful signal and N-1 interference signal that intensity is S that intensity is S.Thereby, the ratio E of bit energy and noise density _b/ N ₀For:

$E_b/N_0=\frac{S/(R\·\mathrm{\α})}{N_t+(N-1)\·S/W}----\left(1\right)$

Wherein, R, a, N _tAnd W is information data rate, the voice activation factor, thermal noise density and transmission bandwidth.The representative value of a is 2/5, and according to the IS-95 suggestion, R and W are given as 9.6kbps and 1.2288MHz.E _b/ N ₀Parameter is the quality factor of digital modulation and demodulation, depends on the implementation of demodulator, and the method for error correction more depends on the needed error rate, and for the situation of desirable power control, the link capacity of said system is about:

$C=\frac{W/(R\·\mathrm{\α})}{E_b/N_0}----\left(2\right)$

When there is N channel occupancy a sub-district, then can obtain signal power S by (1) formula _NFor:

$S_N=\frac{N_t\·W}{\frac{W/(R\·\mathrm{\α})}{E_b/N_0}-(N-1)}----\left(3\right)$

$=\frac{N_t\·W}{C-N+1}$

As can be seen, when the link capacity absorb, S _N=N _tW.The gross power that receives at cell base station BS is:

$P_N=N_t\·W+N\·S_N----\left(4\right)$

$=\frac{C+1}{C-N+1}\·(N_t\·W)$

Make N _Max=C+1, then following formula can be changed into:

$\frac{P_N}{N_t\·W}=\frac{1}{1-\frac{N}{N_{\max }}}----\left(5\right)$

Wherein,

The gross power that receives for the base station and the ratio of background noise, Load percentage for system.

In order to guarantee the stability of system, require the ratio of total noise-plus-interference power that receives to background noise, promptly equivalent ratio I ₀W/N ₀W limits, requirement usually,

$\frac{I_0}{N_0}<\frac{1}{\mathrm{\&eta;}}\mathrm{\&eta;}<1----\left(6\right)$

Its representative value is that η=0.25 is to 0.1, corresponding to power ratio I ₀/ N ₀=6dB to 10dB.

In multi-cell system, inner cell base station BS receives the interference of peripheral cell, can be similar to and regard additivity thermal noise I as ₀, therefore, (4) formula should be:

$P_N=\frac{C+1}{C-N+1}\&CenterDot;(N_t\&CenterDot;W+I_0)----\left(7\right)$

Considering has N business to take channel in the sub-district, because business is of different types, service quality and transmission rate have nothing in common with each other, and supposes that the ratio of i professional bit energy and noise density is E _Ib/ N ₀, the power that signal arrives base station BS is S _i, speed is R _i, activity factor is a _i, for speech business a _i=2/5, data service a _i=1, then:

$E_{\mathrm{ib}}/N_0=\frac{S_i/(R_i\&CenterDot;a_i)}{N_t+\underset{j=1,j\&NotEqual;i}{\overset{N}{\mathrm{\&Sigma;}}}{S}_j/W+I_0/W}----\left(8\right)$

Consider to work as E _Ib/ N ₀Greater than satisfy i business fixed thresholding (E _b/ I ₀) _iThe time, service quality could guarantee.That is,

$\frac{S_i/(R_i\&CenterDot;a_i)}{N_t+\underset{j=1,j\&NotEqual;}{\overset{N}{\mathrm{\&Sigma;}}}{S}_j/W+I_0/W}\&GreaterEqual;{(E_b/I_0)}_i----\left(9\right)$

Following formula can further be written as:

$S_i\left(\frac{W/(R_i\&CenterDot;a_i)}{{(E_b/N_0)}_i}\right)\&GreaterEqual;N_t\&CenterDot;W+\underset{j=1,j\&NotEqual;i}{\overset{N}{\mathrm{\&Sigma;}}}{S}_j+I_0----\left(10\right)$

Order ${\mathrm{\&Gamma;}}_i=\frac{W/(R_i\&CenterDot;a_i)}{{(E_b/I_0)}_i},$ Γ _iOnly relevant with business, by type of service, service rate and service quality decision.Definition P _NThe total power signal that receives for base station BS, then:

$P_N=N_t\&CenterDot;W+\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{S}_j+I_0----\left(11\right)$

Respectively add a S on (10) formula both sides _i, and with (11) formula substitution, then can turn to,

S _i(Γ _i+1)≥P _N (12)

Further be written as:

$S_i\&GreaterEqual;P_N\&CenterDot;\frac{1}{{\mathrm{\&Gamma;}}_i+1}----\left(13\right)$

(13) sue for peace to i in the formula both sides, obtain,

$P_N-(N_t\&CenterDot;W+I_0)\&GreaterEqual;P_N\&CenterDot;\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_i+1}----\left(14\right)$

That is:

$\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_i+1}\&le;1-\frac{N_{t}W+I_0}{P_N}----\left(15\right)$

By following formula as can be known, the cell capacity of multiple-rate business should satisfy $\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_i+1}\&le;1-\frac{N_{t}W+I_0}{P_N}$ Constraints.

Suppose that the sub-district connects with N user, and under the situation of desirable power control, can be similar to and think:

$\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_i+1}=1-\frac{N_{t}W+I_0}{P_N}----\left(16\right)$

After N+1 user asked access, insert N+1 user so, cell capacity should satisfy $\underset{j=1}{\overset{N+1}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_i+1}\&le;1-\frac{N_{t}W+I_0}{P_N+1}$ Constraints, with (16) formula substitution, can obtain:

$1-\frac{N_{t}W+I_0}{P_{N+1}}\&GreaterEqual;\underset{j=1}{\overset{N+1}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_j+1}$

$=\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_j+1}+\frac{1}{{\mathrm{\&Gamma;}}_{N+1}}----\left(17\right)$

$=1-\frac{N_{t}W+I_0}{P_N}+\frac{1}{{\mathrm{\&Gamma;}}_{N+1}+1}$

Can further turn to:

$\frac{N_{t}W+I_0}{P_{N+1}}\&le;\frac{N_{t}W+I_0}{P_N}-\frac{1}{{\mathrm{\&Gamma;}}_{N+1}+1}----\left(18\right)$

$\frac{P_{N+1}}{N_{t}W+I_0}\&GreaterEqual;\frac{\frac{P_N}{N_{t}W+I_0}}{1-\frac{1}{{\mathrm{\&Gamma;}}_{N+1}+1}\&CenterDot;\frac{P_N}{N_{t}W+I_0}}----\left(19\right)$

Here, The gross power that the base station receives when N user arranged in the sub-district and the ratio of background noise,

The gross power that the base station receives when N+1 user arranged in the sub-district and the ratio of background noise, ${\mathrm{\&Gamma;}}_{N+1}=\frac{W/(R_{N+1}\&CenterDot;a_{N+1})}{{(E_b/I_0)}_{N+1}}$ Be the characterization factor that characterizes N+1 customer service, and type of service, service rate is relevant with service quality.

The definition cell capacity is the summation of the data rate of the current link supported of sub-district, and for the sub-district that comprises data and speech business, its value is littler than the sub-district that is speech business merely.Power ratio I when getting the sub-district operate as normal ₀/ N ₀Be 6dB, can obtain the correspondence table that current base station records the professional flank speed of power and noise ratio and permission access:

The ratio (dB) of the gross power that current base station records and noise	Allow the professional flank speed (kbps) of access
		?1	?293.6
?2	?151.2
		?3	?82.4
?4	?42.7
		?5	?17.4

On reverse link, in order to obtain the coverage identical with the voice user, the travelling carriage emitted power must be directly proportional with its data rate.For example, the speed of distribution be voice M doubly, then the average power of travelling carriage emission must be voice M doubly, even higher.

Suppose that a sub-district is for N travelling carriage provides service, when the N+1 travelling carriage inserts.How should its Initial Trans be determined? can obtain by (9) formula:

$S_{N+1}{\mathrm{\&Gamma;}}_{N+1}\&GreaterEqual;N_t\&CenterDot;W+\underset{j=1}{\overset{N}{\mathrm{\&Sigma;}}}{S}_j+I_0----\left(20\right)$

S in the following formula _j, j=1,2 ..., N is the top n travelling carriage emitted power that base station BS receives when the sub-district has N+1 travelling carriage to insert, they will be higher than the received power when having only N travelling carriage.Therefore, (20) formula can be written as:

S _N+1Γ _N+1＞P _N (21)

Here, P _NIt is N+1 the travelling carriage gross power that base station BS receives when not inserting.Suppose the weak P of being of backward channel that base station BS records _Dec(dB), then require N+1 mobile station's initial transmit to be at least:

S _send(dBm)＝P _N(dBm)-Γ _N+1(dB)+P _dec(dB) (22)

On the reverse link, the user of the high data rate in sub-district can cause interference at adjacent cell, thereby takies the capacity of many sub-districts.The size of this interference is determined by the position of user in the sub-district.

For the cellular system of one three sector, as shown in Figure 1, the high data rate user in the A sector causes interference to B, C, D, E, F and G sector, and is wherein particularly serious with B, C sector.Here, be research object with the B sector, suppose to have in the A sector N user to serve, the B sector has M user to serve, and under the situation of desirable power control, system is in stable state.When the A sector had N+1 user to insert, it caused interference to the B sector, the size of interference by this user to the B sector base stations apart from d _BDecision.

If the power that N+1 user arrives the A sector base stations is S, the B sector base stations receives the interference power that N+1 the user in A sector cause and is so $I_{A(N+1)}={\left(\frac{d_B}{d_A}\right)}^{-\mathrm{\&gamma;}}10^{({\mathrm{\&xi;}}_A-{\mathrm{\&xi;}}_B)/10}\&CenterDot;S,$ Wherein the representative value of path attenuation γ is 2.7-5.0.Order $\mathrm{\&mu;}={\left(\frac{d_B}{d_A}\right)}^{-\mathrm{\&gamma;}}{10}^{({\mathrm{\&xi;}}_A-{\mathrm{\&xi;}}_B)/10},$ Then this interference power is μ S.Similar to (8) formula, B sector user satisfies condition:

$\frac{S_{\mathrm{Bi}}/(R_{\mathrm{Bi}}\&CenterDot;a_{\mathrm{Bi}})}{N_t+\underset{j=1,j\&NotEqual;i}{\overset{M}{\mathrm{\&Sigma;}}}{S}_{\mathrm{Bj}}/W+I_0/W+\mathrm{\&mu;S}/W}\&GreaterEqual;{(E_b/I_0)}_{\mathrm{Bi}}----\left(23\right)$

Further turn to:

S _Bi(Γ _Bi+1)≥P′ _BM (24)

Wherein, $P_{\mathrm{BM}}^{\&prime;}=N_{t}W+\underset{j=1}{\overset{M}{\mathrm{\&Sigma;}}}{S}_{\mathrm{Bj}}+I_0+\mathrm{\&mu;S}$ Be after N+1 user and A sector base stations are set up service, the gross power that the B sector receives.

(24) the formula both sides are respectively divided by Γ _Bi+ 1 also summation obtains:

$P_{\mathrm{BM}}^{\&prime;}-(N_{t}W+I_0+\mathrm{\&mu;S})\&GreaterEqual;P_{\mathrm{BM}}^{\&prime;}\&CenterDot;\underset{j=1}{\overset{M}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_{\mathrm{Bj}}+1}----\left(25\right)$

That is:

$\underset{j=1}{\overset{M}{\mathrm{\&Sigma;}}}\frac{1}{{\mathrm{\&Gamma;}}_{\mathrm{Bj}}+1}\&le;1-\frac{N_{t}W+I_0+\mathrm{\&mu;S}}{P_{\mathrm{BM}}^{\&prime;}}----\left(26\right)$

Compare with (15) formula, the B sector can keep stable after N+1 user and A sector base stations foundation service, must satisfy following conditions:

$1-\frac{N_{t}W+I_0}{P_{\mathrm{BM}}}\&le;1-\frac{N_{t}W+I_0+\mathrm{\&mu;S}}{{\mathrm{\&Rgr;}}_{\mathrm{BM}}^{\&prime;}}----\left(27\right)$

Wherein, P _BMThe gross power that the B sector base stations receives when not inserting for N+1 user.

(27) formula is dissolved, can be obtained following formula at last:

$\frac{P_{\mathrm{BM}}}{N_{t}W+I_0}+\frac{\mathrm{\&mu;S}}{N_{t}W+I_0}\&CenterDot;\frac{P_{\mathrm{BM}}}{N_{t}W+I_0}\&le;\frac{P_{\mathrm{BM}}^{\&prime;}}{N_{t}W+I_0}----\left(28\right)$

The threshold value when as long as the inequality left side is no more than the sub-district operate as normal, so, after N+1 user and A sector base stations foundation service, the interference that the B sector is subjected to is unlikely to make system's instability.

By (21) formula, estimate that the size of S is about

Then (28) formula becomes,

$\frac{P_{\mathrm{BM}}}{N_{t}W+I_0}+\frac{\mathrm{\&mu;}}{{\mathrm{\&Gamma;}}_{A(N+1)}}\&CenterDot;\frac{P_{\mathrm{AN}}}{N_{t}W+I_0}\&CenterDot;\frac{P_{\mathrm{BM}}}{N_{t}W+I_0}\&le;\frac{P_{\mathrm{BM}}^{\&prime;}}{N_{t}W+I_0}----\left(29\right)$

Wherein,

It is respectively N+1 user's gross power that A, B base station receive when not inserting and the ratio of background noise.Consider that μ is an amount relevant with customer location, the ratio of the neighbor base station pilot frequency intensity that it can be recorded by mobile phone is definite.

Get γ=4, $\frac{P_{\mathrm{AN}}}{N_{t}W+I_0}=2\mathrm{dB},$ $\frac{P_{\mathrm{BM}}}{N_{t}W+I_0}=5\mathrm{dB},$ Can obtain With the correspondence table of the professional flank speed that allows to insert, thresholding I ₀/ N ₀Still be 6dB.Can obtain the correspondence table that current base station records the traffic carrying capacity flank speed of power and noise ratio and permission access:

Concrete enforcement of the present invention is discussed below.

The cdma cellular mobile communication system of present embodiment is with reference to figure 1, and pattern configurations is with reference to figure 2.Shown in Figure 1 is three sector schematic diagrames, comprises seven sub-districts among the figure, and there are three sectors each sub-district, and the base station distributes in the summit mode; The travelling carriage 12 that communicates with the base station that comprises a plurality of base stations 11 and a plurality of extended code modulation signals of a plurality of use among Fig. 2.Suppose that each base station 11 uses a frequency bandwidth of being shared by a plurality of users to be used for each up link and a frequency bandwidth of being shared by a plurality of users is used for each down link, and same frequency bandwidth is used in all base stations 11.

In the base station 11 of Fig. 2, call permission control method of the present invention is as follows by implementing:

Speech business access thresholding and data service access thresholding at first are set respectively in the base station, in this example, suppose current N the user that inserted, that request inserts is N+1 user, and it is the ratio I of total interference power of base station reception to background noise that speech business access thresholding is set ₀/ N ₀, its value is 10dB, data service access thresholding is the ratio I of total interference power of base station reception to background noise ₀/ N ₀, its value is 6dB.Make the base station regularly receive the measurement report of the total interference power in sub-district, and use noise power N ₀Be recorded in the data storage after the normalization; And, operate by the following step that this method comprises: with reference to figure 3.

In step 1, insert the call connection request of carrying information such as data rate, service quality; In step 2, read the interference value of sub-district current in the buffer memory and the threshold value of professional access; In step 3, whether judge interference value that above-mentioned steps 2 reads less than the access threshold value, if less than the access threshold value, execution in step 12, otherwise execution in step 4; In step 4, predict that N+1 user inserts the interference value of this sub-district, back, in step 5, whether judge interference value that above-mentioned steps 4 obtains less than threshold value, as if less than, execution in step 6, otherwise execution in step 9; In step 6, from the data storage of this cell base station, read the interference prediction value of adjacent cell and the threshold value of professional access; In step 7, predict that N+1 user inserts the interference value of back adjacent cell; In step 8, whether judge interference value that above-mentioned steps 7 obtains less than threshold value, if less than, execution in step 10, otherwise execution in step 9; In step 9, judge whether N+1 the user's data that inserts is business datum, if, execution in step 11, otherwise execution in step 12; Carry out call admission in step 10 and handle, finish this then and call out access operation; Carry out service negotiation in step 11 and handle, finish this then and call out access operation; Carry out call denial in step 12 and handle, finish this then and call out access operation.

When N+1 user of prediction inserts the interference value of back this sub-district, carry out according to following method: according to the data rate R that comprises in the call request message, the ratio E of bit energy and noise density _b/ N ₀Or can be converted into the signal to noise ratio SIR of bit energy and the ratio of noise density, with following formula calculate insert this speed ratio data service after, the interference value I of this sub-district ₀/ N ₀, respectively with subscript N and N+1 difference, ${(I_0/N_0)}_{N+1}\&GreaterEqual;\frac{{(I_0/N_0)}_N}{1-\frac{1}{{\mathrm{\&Gamma;}}_N+1}\&CenterDot;{(I_0/N_0)}_N}$ Wherein: ${\mathrm{\&Gamma;}}_{N+1}=\frac{W/(R_{N+1}\&CenterDot;a)}{{(E_b/N_0)}_{N+1}}$

W is an apread spectrum bandwidth, and a is an activity factor, for data service, and a=1, T _νBe speech business access thresholding, T _dBe data service access thresholding.

When N+1 user of prediction inserts the interference value of back adjacent cell, carry out according to following method: this district pilots intensity and adjacent cell pilot frequency intensity according to moving table measuring calculate the ratio of travelling carriage apart from the wireless distances of adjacent cell base station and this cell base station, with transmitting power according to the travelling carriage of estimating, predictive call inserts the interference value of back adjacent cell, concrete grammar is: establishing this sub-district and adjacent cell base station is A and B, and travelling carriage is d to this cell base station and adjacent cell base station radio distance _AAnd d _B, make μ=(d _B/ d _A) ^-γ, wherein to get representative value be 4 to γ, use following formula calculate the user the A sub-district insert call out after, the interference value (I of the adjacent cell of prediction ₀/ N ₀) _B', ${\left(\frac{I_0}{N_0}\right)}_B^N\&GreaterEqual;{\left(\frac{I_0}{N_0}\right)}_B+\frac{\mathrm{\&mu;}}{{\mathrm{\&Gamma;}}_{N+1}}\&CenterDot;{\left(\frac{I_0}{N_0}\right)}_A\&CenterDot;{\left(\frac{I_0}{N_0}\right)}_B$ Wherein: ${\mathrm{\&Gamma;}}_{N+1}=\frac{W/R_{N+1}}{{(E_b/N_0)}_{N+1}}.$ Above the transmitting power of travelling carriage of described estimation carry out according to following method:

That is N+1 mobile station's initial transmit S, _Send(dBm) be:

S _send(dBm)＝P _N(dBm)-Γ _N+1(dB)+P _dec(dB)

P _N(dBm) be N+1 the travelling carriage gross power that base station BS receives when not inserting, P _Dec(dB) backward channel that records for base station BS is weak.

Handle according to following step operation carrying out call admission:

In step 1, the call admission control unit has judged whether idle orthogonal code, if having, and execution in step 2, otherwise execution in step 4; In step 2, the call admission control unit judges whether the baseband processing unit of a free time, if having, and execution in step 3, otherwise execution in step 4; In step 3, the call admission control unit is permitted the processing that this calling enters, and finishes this then and calls out access operation; In step 4, control unit is handled the operation that refusal is called out, and finishes this then and calls out access operation.

Carrying out the described service negotiation that carries out when handling, according to following step operation: with reference to figure 4.

In step 1, the data service request inserts, and predicted interference is greater than threshold value; Calculate this sub-district in step 2 with following formula and can allow the maximum data rate R that inserts _Max1,

${\mathrm{\&Gamma;}}_{N+1}=\frac{W/R_{\max 1}}{{(E_b/N_0)}_{N+1}}$

$T_d\&GreaterEqual;\frac{{(I_0/N_0)}_N}{1-\frac{1}{{\mathrm{\&Gamma;}}_N+1}\&CenterDot;{(I_0/N_0)}_N};$ Wherein, T _dBe data service access thresholding;

In step 3, the maximum data transfer rate R that the Target cell that does not cause adjacent cell to surpass threshold value with following formula calculating can insert _Max2,

${\mathrm{\&Gamma;}}_{N+1}=\frac{W/R_{\max 2}}{{(E_b/N_0)}_{N+1}}$

$T_d\&GreaterEqual;{\left(\frac{I_0}{N_0}\right)}_B+\frac{\mathrm{\&mu;}}{{\mathrm{\&Gamma;}}_{N+1}}\&CenterDot;{\left(\frac{I_0}{N_0}\right)}_A\&CenterDot;{\left(\frac{I_0}{N_0}\right)}_B;$

In step 4, consult with min (Rm with the mobile subscriber _Ax1, R _Max2) insert; In step 5, judge whether negotiation is successful, if consult successfully, then with min (R _Max1, R _Max2) insert and call out, otherwise, call congestion.

Claims (7)

1. A control method for calling permission in a code division multiple access mobile communication system, characterized in that: the method includes: setting a voice service access threshold and a data service access threshold respectively at the base station, so that the base station receives the total interference of the cell regularly The measurement report of power, and record in the data memory after normalizing with noise power _N ; And, this method also comprises following operation steps: (1) Access a call connection request carrying information such as data rate and quality of service; (2) read the interference value of the current cell in the cache and the threshold threshold of service admission; (3) Judging whether the interference value read in the above step (2) is less than the access threshold threshold, if it is less than the access threshold threshold, perform step (12), otherwise perform step (4); (4) Predict the interference value of the cell after the N+1th user accesses; (5) Judging whether the interference value obtained in the above step (4) is less than the threshold threshold, if less, perform step (6), otherwise perform step (9); (6) Read out the interference prediction value of the adjacent cell and the threshold threshold value of service admission from the data memory of the base station of the cell; (7) Predict the interference value of the adjacent cell after the N+1th user accesses; (8) Judging whether the interference value obtained in the above step (7) is less than the threshold threshold, if less, perform step (10), otherwise perform step (9); (9) judge whether the data of the N+1th user of access is business data, if yes, execute step (11), otherwise execute step (12); (10) Carry out call permission processing, then end this call access operation; (11) Carry out business negotiation processing, then end this call access operation; (12) Perform call rejection processing, and then end the current call access operation. 2. The method for controlling call admission in the code division multiple access mobile communication system according to claim 1, wherein the interference value of the sub-district after the prediction of the N+1 user access is carried out according to the following method: According to the data rate R contained in the call request message, the ratio of bit energy to noise density E _b /N ₀ or the signal-to-noise ratio SIR that can be converted into the ratio of bit energy to noise density, use the following formula to calculate the data access rate The interference value of the cell after the service is I ₀ /N ₀ , and the interference values before access and after access are distinguished by subscripts N and N+1 respectively, ${(I_0/N_0)}_{N+1}\&Greater\; Equal;\frac{{(I_0/N_0)}_N}{1-\frac{1}{{\mathrm{\&Gamma;}}_N+1}\&Center\; Dot;{(I_0/N_0)}_N}$ in: ${\mathrm{\&Gamma;}}_{N+1}=\frac{W/(R_{N+1}\&CenterDot;\mathrm{\&alpha;})}{{({\mathrm{E.}}_b/N_0)}_{N+1}}$ W is the spread spectrum bandwidth, a is the activation factor, and for data services, a=1. 3. The method for controlling call admission in the code division multiple access mobile communication system according to claim 1, wherein said prediction of the interference value of the adjacent cell after the N+1 user accesses is carried out according to the following method: Calculate the ratio of the wireless distance between the mobile station and the base station of the adjacent cell and the base station of the local cell according to the pilot frequency strength of the mobile station measured by the local cell and the pilot signal strength of the adjacent cell, and predict the adjacent cell after the call is accessed according to the estimated transmission power of the mobile station The specific method is as follows: set the base station of the own cell and the adjacent cell as A and B, and the wireless distances from the mobile station to the base station of the own cell and the base station of the adjacent cell are d _A and d _B , and μ=(d _B /d _A ) ^{- γ} , where γ takes a typical value of 4, use the following formula to calculate the predicted interference value (I ₀ /N ₀ ) _B ′ of the adjacent cell after the user accesses the call in cell A, ${\left(\frac{I_0}{N_0}\right)}_B^{\&prime;}\&Greater\; Equal;{\left(\frac{I_0}{N_0}\right)}_B+\frac{\mathrm{\&mu;}}{{\mathrm{\&Gamma;}}_{N+1}}\&CenterDot;{\left(\frac{I_0}{N_0}\right)}_A\&CenterDot;{\left(\frac{I_0}{N_0}\right)}_B$ in: ${\mathrm{\&Gamma;}}_{N+1}=\frac{W/R_{N+1}}{{({\mathrm{E.}}_b/N_0)}_{N+1}}.$ 4. The method for controlling call permission in the code division multiple access mobile communication system according to claim 1, characterized in that, the described call permission process is performed according to the following steps: (1) The call admission control unit judges whether there is an idle orthogonal code, and if so, executes step (2), otherwise executes step (4); (2) call admission control unit judges whether there is an idle baseband processing unit, if there is, execute step (3), otherwise execute step (4); (3) The call admission control unit performs the processing of allowing the call to enter, and then ends the call access operation; (4) The control unit processes the call rejection operation, and then ends the call access operation. 5. The method for controlling call admission in the code division multiple access mobile communication system according to claim 1, characterized in that, said carrying out business negotiation process is operated according to the following steps: (1) The data service requests access, and the predicted interference is greater than the threshold; (2) Use the following formula to calculate the maximum data rate R _max1 that is allowed to be accessed in this cell, ${\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}$ $T_d\&Greater\; Equal;\frac{{(I_0/N_0)}_N}{1-\frac{1}{{\mathrm{\&Gamma;}}_N+1}\&CenterDot;{(I_0/N_0)}_N};$ Among them, T _d is the data service access threshold; (3) Use the following formula to calculate the maximum data transmission rate R _max2 that can be accessed by the target cell without causing the adjacent cell to exceed the threshold value, ${\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}$ ${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; \&Greater\; Equal;</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}{{\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; ;</span>$ (4) Negotiate with the mobile user to access with min( _Rmax1 , R _max2 ); (5) Judging whether the negotiation is successful, if the negotiation is successful, access the call with min(R _max1 , R _max2 ), otherwise, the call is blocked. 6. The method for controlling call admission in the code division multiple access mobile communication system according to claim 3, wherein the estimated initial transmission power of the mobile station is carried out according to the following method: The initial transmit power S _send (dBm) of the N+1th mobile station is: S _send (dBm)＝P _N (dBm)-Γ _N+1 (dB)+P _dec (dB) P _N (dBm) is the total power received by the base station when the N+1th mobile station is not connected, and P _dec (dB) is the reverse channel attenuation from the N+1th mobile station to the base station estimated by the base station. 7. The method for controlling call admission in a code division multiple access mobile communication system according to claim 1, characterized in that: the voice service access threshold is set to 10dB, and the data service access threshold is set to 6dB.

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