THE WAY OF CALCULATING THE TRAFFIC AND SIGNALING NETWORK DIMENSION OF COMMON CHANNEL SIGNALING NO.7 (CCS7)

Transcription

1 The Way of Calculatig The Traffic... THE WAY OF CALCULATIG THE TRAFFIC AD SIGALIG ETWORK DIMESIO OF COMMO CHAEL SIGALIG O.7 (CCS7) Departeme Tekik Elektro, Fakultas Tekik, Uiversitas Sumatera Utara Abstract: Calculatig the traffic ad dimesio eeds to be doe at the plaig of telecommuicatio etwork, because, by calculatig the traffic we will fid out the amout of the traffic which will be trasferred ad by calculatig the dimesio we will fig out the amout of the etwork eeds to be provided. Ad at the CCS7 sigalig etwork as well, calculatig the traffic ad dimesio eeds to be implemeted. CCS7 costitutes multi-fuctio sigalig type which eables to the trasfer the whole iformatio data such as voice, computer data i high speed, ad visio, which ca be cotrolled through the CCS7 sigalig etwork. CCS7 sigalig system is oly able to work i digital cetral, costitutes the last sigalig system of the group of telephoe sigalig recommeded by Iteratioal Telecommucatio Uio (ITU) which previously amed Committee Cosultative /Iteratioal Telegraph ad Telephoe (CITT), which works by out of bad (commo chael) so the etwork supported ca efficietly work. I calculatig the traffic ad dimesio CCS7 ivolves four objects, i.e. by calculatig the traffic iter ed ode called Sigalig Ed Poit (SEP) iter traffic, calculatig the traffic i coectio lie iter ode called likset traffic, ad calculatig the ode dimesio called Sigalig Poit () dimesio. is geeral ode, which ca be SEP or Sigalig Trasfer Poit (). The method of calculatig the four objects i calculatig the traffic ad dimesio of CCS7 lies i this paper.. ITRODUCTIO The eed of telecommuicatio service for the user is more various, thus the high speed, effective, ad efficiet sigalig system is eeded. CCS7 costitutes a solutio of sigalig system which has the ability to give excellet telecommuicatio service which: Has optimal ability to use i digital commuicatio etwork together with cetral digital of stored program cotrol, used the digital caal of 64 Kbps Is desiged for iformatio trasfer call cotrol provisio for ow ad i the future, remote cotrol, maagemet ad maiteace Has the good ability i trasferrig the iformatio with correct sequece without loss. Some applicatios which ca be supported by CCS7 are Public Switch Telephoe. etwork (PST), Itegrated Switch Digital etwork (ISD), Itelligece etwork (I), Persoal Commuicatio etwork (PC). (CCITT, 98). I desigig the sigalig etwork CCS7, we eed to calculate the traffic ad dimesio. First of all, we will discuss the calculatio of the traffic iter SEP. With the result of the calculatio, we cotiue calculatig the likest traffic. Furthermore, accordig to the result of likset traffic calculatig we will discuss about the calculatig of Likset Dimesio ad Dimesio. Traffic iter SEP is calculated by fidig out the iput data i.e. callig ad sigalig data ; the calculatio is doe by multiplyig the callig data ad sigalig data. Whereas, likset traffic is calculated by fidig out the iput data i.e. iter traffic SEP ad route arragemet ; the calculatio is doe by summig up every SEP iter traffic which is routed to the likset. Likset dimesio is faster calculated, which is determied by the iput data i.e. the byte itegratio likset traffic. The determiatio is doe by usig the table of maximum likset capacity made by ITU. dimesio is calculated by the iput data i.e. traffic likset itegratio of Message Sigal Uit (), ad the calculatig is doe by summig up all the likset traffic set ad received by.. CCS7 ARCHITECTURE Telecommuicatio etwork is made from several switchig ad processig ode itercoected by the lik trasmissio. I this 73

2 Jural Sistem Tekik Idustri Volume 7, o. April 006 case, commuicatio by usig CCS7, the odes eed feature CCS7 so that they ca be fuctioed as. is a ode which is able to hadle the cotrol message of CCS7. I order make the iformatio or the data ca be set or received iter, the itercoectio through lik sigalig is eeded. I CCS7, the cotrol message is routed i shape of packages through the etwork for formig call maagemet fuctio (set up, maiteace, termiatio) ad maagemet etwork fuctio. Oe circuit is determied by the local cetral i which oe user is coected to aother user by passig oe or more other circuit switchig ode used as Trasit Ceter (TC). Figure shows the architecture of CCS7 i telecommuicatio etwork (). USER USER CCS7 TC TC Cotrol Plae Iformatio Plae TC USER USER Figure. Architecture of CCS7 i telecommuicatio etwork 3. ETWORK MODEL OF PST, I, AD CCS7 I calculatig the traffic ad dimesio of CCS7, we ca see the etwork model i Figure to help the discussio: SEP D LIKSET CIRCUIT GROUP SEP D SCP LIKSET E SEP D LIKSET LIKSET CIRCUIT GROUP S SEP LT Figure. etwork model: Public Switch Telephoe etwork (PST); Itelliget etwork (I), ad Commo Chael Sigalig o.7 (CCS7). I figure, there are 3 etworks i.e. PST, I, ad CCS7 etwork. PST ad I etwork represet the etwork served by CCS7, ad CCS7 etwork itself i.e. the etwork which will discuss for the traffic ad dimesio calculatig. PST etwork i Figure, is determied by three ode, i.e. ode A as Local Exchage () called A (), ode B as Local Trasit exchage (LT) called ode B (LT); ad ode C as Local Exchage () called ode C (). I PST etwork, the coectio lies of ode A (),B (LT) ad C () is represeted by thick lie i the shape of circuit group.(itu,99) I etwork i figure is determied by odes, i.e. ode B as Service Switchig Poit (S) called ode B (S), ad ode D as Service Cotrol Poit (SCP) called ode D (SCP). I this etwork, betwee ode B (S) ad ode D (SC) (broke lie) there is o coectio lie iter odes, because the likset coectig S ad SCP through Sigalig Trasfer Poit () cosidered as a part of CCS7 etwork. CCS7 etwork i figure is represeted by 5 odes, i.e.: ode A, ode B, ode C, ad ode D, as Sigalig Ed Poit (SEP) called as ode A (SEP), B (SEP), C (SEP), D (SEP), ad ode E as Sigalig Trasfer Poit () which is called as ode E (). I this etwork, the coectio lie iter ode A (SEP), B (SEP), C (SEP), D (SEP), ad E () i the shape of likset is represeted by broke lies. The model of CCS7 etwork is arraged i star cofiguratio, where SEP is oly coected to, which meas sigalig iter SEP is always routed through. (ITU, 99) Although the model above oly describe the service of CCS7 to PST ad I etwork. But it also ca represet the service to cellular D 74

3 The Way of Calculatig The Traffic... etwork. For example GSM (Global System for Mobile Commuicatio), where S ad SCP i I ca be equalized respectively with MSC/VLR (Mobile Switchig Ceter/Visitor Locatio Register) ad HLR (Home Locatio Register). Whereas, ad LT i PST ca be equalized with MSC i GSM. 4. CALCULATIG THE TRAFFIC AD DIMESIO OF CCS7 ETWORK Calculatig the traffic ad dimesio of CCS7 ivolves 4 objects, i.e.: Calculatig the traffic iter ed ode called traffic iter SE Calculatig the traffic i coectio lie iter ode called likset traffic Calculatig the dimesio of coectio lie iter ode called likset dimesio Calculatig the ode dimesio called dimesio The ways of calculatig the 4 objects above will be discussed i this paper. 4. The way of Calculatig the Traffic iter ed ode (Traffic iter SEP) (Message Sigal Uit) curret which moves from a SEP to other SEP through likset is the shape of sigalig traffic of CCS7, where i this curret of CCS7 etwork, there are kids of traffic, amely: The traffic from oe SEP to aother SEP by igorig likset (traffic iter SEP). Traffic iter SEP oly coected to the source ad destiatio ode, ot iflueced by the etwork cofiguratio ad traffic routig patter i the etwork. The traffic that flows to the likset (likset traffic) costitutes routig result of some traffic iter SEP to the likset. The calculstio of traffic iter SEP must be calculated for each sigalig directios. Because callig directio (circuit occupatio) occurred betwee two PST odes is two directios, so sigalig directio servig PST is also directios. Whereas, because the callig directio (traslatio digit demad) occurred betwee two odes I is oly oe directio (from S to SCP), so sigalig directio betwee two SEP servig I is oe directo. (ITU, 99) Because of iteractive feature of sigalig. -forward traffic ad -reverse traffic occurred i every sigalig directios. Cosequetly, -forward traffic ad reverse traffic must be calculated i every sigalig directios. Thus, for example, the model i Figure, traffic iter SEP which must be calculated ca be see i Table. The data eeded to calculate iter SEP are: Callig data (occupatio of circuit for PST ad digit traslatio demad I) Sigalig demad ( data/callig ad byte/) For the callig data, it eeds: The umber of callig/sec = P Success callig ratio = PS (%) Table. Traffic Iter SEP Which Must be Calculated for the Model i Figure Sigalig directio o sigalig directio Traffic Calculated otes A to B - Traffic - forward - A to B - Traffic - reverse - B to A - Traffic -forward - B to A - Traffic -reverse - B to C - Traffic -forward - B to C - Traffic -reverse - C to D - Traffic -forward - C to D - Traffic -reverse - B to D - Traffic -forward - B to D - Traffic -reverse - - D to B - Because i I the callig (digit traslatio demad) from SCP to S ever occurs - A to C C to A - Because there is o circuit betwee A () ad C (), so that there is o callig (sirsuit occupatio) betwee the odes 75

4 Jural Sistem Tekik Idustri Volume 7, o. April 006 Table. The Data eeded to the Calculatio Iter SEP for Callig Data i the Model i Figure Callig Directios Kids of service Callig/sec = (P) Success Callig Ratio = (PS) % A () to B (LT) B (LT) to A () B(LT) to C () C () to B (LT) B (S) to D (SCP) Table 3. Data eeded for Iter SEP Calculatio for Sigalig Data i the Model Sample i Figure Sigalig Directio Kids of Service Success Callig Fail Callig A(SEP) to B(SEP) B(SEP) to A(SEP) B(SEP) to C(SEP) C(SEP) to B(SEP) B(SEP) to D(SEP) forward/ callig Byte/ forward reverse/ callig Byte/ reverse forward/ callig Byte/ forward reverse/ callig Byte / reverse The complete data eeded for the calculatio of ite SE for Callig Data i the example of Figure ca be see i Table. That is so the complete data eeded to calculate traffic iter SEP for Sigalig Data i the model i Figure : The average umber of -forward/the callig for success callig = _MS (/Callig) The average umber of Byte/-forward for success callig = Byte_MS (Byte/) The average umber of -reverse/the callig for success callig = _BS (/Calllig) The average umber of Byte/-reverse for success callig = Byte_BS (Byte/) The average umber of -forward/the callig for fail callig = _MG (/callig) The average umber of Byte/-forward for fail callig = Byte_MG (Byte/) The average umber of -reverse/the callig for fail callig = _BG (/Callig) The average umber of Byte /-reverse for fail callig = Byte_BG (Byte/) For the calculatig of traffic iter SEP for Sigalig Data above, for example i Figure ca be see i Table 3. The sigalig data eeded is data /callig ad byte/. Byte/ is used to chage uit to byte. Because of the traffic calculatio output is stated i two uits, 76

5 The Way of Calculatig The Traffic... i.e. ad byte, so we eed to chage from to byte, whereas is later for calculatig the likset dimesio. The callig ad sigalig data above is eeded for every callig directio or sigalig ad kids of services, because every callig directio or sigalig has differet callig characteristics or sigalig although they are i the same service. Ad also every kid of services has differet callig or sigalig characteristics, although the callig or sigalig directio are the same. (ITU 99). I PST, if the callig data/secod is ot provided, for data istead ca be used is the data volume traffic i erlag or data of circuit umber, ad because the data eeded is the umber of callig/secod, the data of erlag traffic or the umber of circuit must be chaged first ito the shape of callig/secod before used for the calculatio iter SEP. I order to chage erlag traffic data ito the shape of callig/secod, we eed the data of average circuit held time i secod (W). Thus, the chage of erlag traffic data ito the form of callig/secod ca be doe by usig formula (Siemes AG, 994): Callig/sec = traffic (erlag) = W (sec) () By addig the circuit umber data first ito the erlag traffic ad from the traffic erlag the chaged ito the callig/secod, we ca chage the circuit umber data ito callig/secod. The chagig of circuit umber data ito the erlag traffic is usig circuit efficiecy parameter obtaied by usig the formula (Siemes, 994): Erlag traffic = Efficiecy (%) X total circuit () The calculatio of traffic iter SEP for every directios of must be doe two times because the output respectively result i output with uit ad byte. So, the calculatio of traffic which must be doe for every sigalig directios became two directio of MS with two calculatio each, results i the calculatio of traffic for every sigalig directios became four times calculatio. The callig data ad sigalig data provided by every sigalig directios are the data per kid of service. So, the traffic iter SE per sigalig directio costitutes the agregasio from traffic per kid of service (Siemes AG, 994). The calculatio of traffic iter SEP for every sigalig directios which cotais four calculatio (every sigalig directios becomes two directios of with two calculatios each) ca be doe by the formula below. Sigalig X to Y: Traffic -forward (/sec) = = Pi {PSi x _MSi + (-PSi) x _MGi} (3) i= traffic -forward (bytesec)= = Pi {PSi x _MSi x Byte_MSi+ (- PSi)x_MGixyte_MGi}..(4) i= Traffic -reverse (sec)= = Pi {PSi x _BSi + (-PSi) x _BGi}...(5) i= traffic -reverse (bytesec)= = Pi {PSi x _BSi xbyte_bsi+(- PSi)x_BGixByte_BGi}..(6) i=kid of service Where: _MS (/Callig) = the average umber of -forwardthe callig for success callig Byte_MS (Byte/) = the average umber of Byte/-forward for success callig. _BS (/Callig) = the average umber of -reverse/the callig for success callig. Byte_BS (Byte/) = the average umber of Byte/-reverse for success callig. _MG (/Callig) = the average umber of -forward/the callig for fail callig. Byte_MG (Byte/) = the average umber of Byte/-forward for fail callig. _BG (/Callig) = the average umber of -reverse for fail callig. 77

6 Jural Sistem Tekik Idustri Volume 7, o. April The Way to Calculate the Traffic i Coectio Lie iter ode (Traffic Likset) Likset is the coectio lie iter ay ode CCS7 to SEP as well as. The Traffict that flows i likset traffic costitutes the traffic preset i the etwork, ad obtaied from the traffic routig iter SEP to the likset. So, the Likset traffic will be iflueced by the etwork cofiguratio ad the traffic rouig patter as well. Likset traffic is ot calculated for every sigalig directios, but for every likset. This is because the likset traffic costitutes the traffic iter ay ode is ot always the sigalig passer ode or SEP. Although the two directio is always i every likset, the directio of traffic ca ot be stated as -forward traffic ad reverse traffic. The directio of traffic is oly stated as two SEP/ which flaks the likset. This is because the -forward traffic ad -reverse traffic preset i oe sigalig directio i the traffic iter SEP is routed i oe idetic likset. Ad there is o sigalig directio referece because the traffic iter ay ode is ot always sigalig ode. (Siemes AG,994). For the sample model i Figure, the likset traffic calculatio must calculated ad ca be see i Table 4. Table 4. Likset Traffic Which Must be Calculated for Model Sample i Figure Likset Likset Traffic Which Must be calculated AE traffic from A to E AE traffic from E to A CE traffic from C to E CE traffic from E to C BE traffic from B to E BE traffic from E to B DE traffic from D to E DE traffic from E to D All traffic iter SEP is always routed through, so for the model sample i Figure, the Likset traffic calculatio for every likset is: Table 5. The Calculatio of Likset Traffic for Model Sample i Figure Likset Traffic Likset Traffic Calculatio from. AE A to E = -forward traffic A to B sigalig + -reverse traffic B to A sigalig (7) AE E to A = -forward traffic B to A sigalig + -reverse traffic A to B sigalig (8) CE C to E = -forward traffic C to B sigalig + -reverse traffic B to C sigalig (9) CE E to C = -forward traffic B to C sigalig + -reverse traffic C to B sigalig (0) BE B to E = -forward traffic B to A sigalig + -reverse traffic A to B sigalig + -reverse traffic C to B sigalig + forward traffic B to D sigallig () BE E to B = -forward traffic A to B sigalig + -reverse traffic B to A sigalig + -forward traffic C to B sigalig + reverse traffic B to D sigallig () DE D to E = -forward traffic B to D sigalig (3) DE E to D = -forward traffic B to D sigalig (4) The calculatio i Table 5 is respectively doe by usig: first, the uit, ad secod, the output byte from the traffic iter SEP. 78

7 The Way of Calculatig The Traffic The Way to Calculated the Dimesio of Iter ode Coectio Lie (Likset Dimesio) Coectio lie iter ay ode (likset) coectig costitutes the sigalig lik horde, ay the digital trasmissio caal costitutes the shape of sigalig lik, i which the are two trasmissio directio which has the speed of 64 Kbit/secod or 8Kbyte/secod. The speed of sigalig lik trasmissio besides the bearer of the traffic is also stated as the capacity of sigalig lik traffic, ad the capacity of sigalig lik of 8Kbyte/secod as metioed above ca ot etirely be allocated to carry the traffic whe thr coditio of the etwork is ormal. This meas the maximum utilizatio rate of the sigalig lik of the ormal coditio of the etwork (im) is allowed less tha 00%. This is to accommodate additio traffic whe the disturbace is occurred, such as disruptio of which cause retrasfer or disruptio of sigalig lik, which is caused the movemet of the traffic from oe sigalig to aother sigalig. The capacity of maximum sigalig lik (KImax) i the traffic whe the coditio of the ormal etwork is: Kl-max=im x 8 Kbyte/sec...(5) The value of this im umber betwee 0 % ad 40% is accordig to ITU recommedatio. The small im umber (0%) is used if lik disturbace ad retrasfer of ofte occurred where the coditio of the etwork is predicted bad ad it eeds a huge umber of reserve capacity, where as this big im umber (40%) is used if the lik disturbace ad the retrasfer of is rarely occurred where the coditio of the etwork is predicted good ad does ot eed the huge umber of reserve capacity. Thus, we eed to cosider the coditio of the etwork i determiig the value of the umber. (ITU,99). The capacity of maximum likset (Klsmax) preset i the likset is which states the likset maximum load. If Kls-max is distributed to the lik, cosequetly, every liks get the Klmax load. Ad if the load of the result of distributio get the load iter lik ca be equal, cosequetly every lik will get the Kl-max load ad the value of Kls-max is: Kls-max= x Kl-max.(6) Where as, if the load of distributio result gets the load iter lik uequal, there will be lik which gets the load= Kl-max ad aother lik gets the load<kl-max ad Kls-max< x Klmax. By cosiderig the load distributio is equal, the calculatio formula of the lik dimesio is as follow: Likset Dimesio= Likset Traffic(Byte/sec)...(7) Kl-Max(Byte/sec) But i applyig, the result of load distributio is ot equal, so the calculatio of likset dimesio of the formula (7) above ca ot be used. If we use the calculatio of likset dimesio by usig the table 6,i.e the table of maximum likset capacity made by ITU, we will get more exact result (ITU,99). Table 6 showws the relatioship betwee Kls-max i Kl-max uit toward the total sigalig lik, where Kls-max is ot always added toward the total lik accretio. Table 6. Maximum Likset Capacity Toward the Total Lik Total Lik Kls-max Distirbutio System 4 it Distributio System 3 Bit Kl-max Kl-max 8/3 Kl-max Kl-max 6/3 Kl-max 6/3 Kl-max 8 Kl-max Kl-max Kl-max 8/3 Kl-max 8 Kl-max By usig Table 6, we ca be determied the likset dimesio by: First, we idetify the distributio system used whether the system is 4 bit or 3 bit Based o the estimate soditio of the etwork, determied the value of Kl-max Chage the resultof likset traffic calculatio with byte/sec uit, ito Kl-max uit Based o distributio system which used 4 bit or 3 bit, we determie i appropriate colum with distributio system, the same Kls-max value with the value of likset traffic or higher After we get the value of Kl-max, thus we ca determie the umber of lik or likset dimesio As a sample, to determie the likset dimesio ca be see o the clarificatio below: 79

8 Jural Sistem Tekik Idustri Volume 7, o. April 006 Example : Load distributio system used is 4 bit The coditio of the etwork is estimated well, im is determied 35%, so Kl-max 35% x 8 Kbyte/sec =.8Kbyte/sec If the likset traffic is 8.4 Kbyte/sec (3Klmax), 3 Kl-max ca ot be foud i Table 6 i the colum of distributio system of 4 bit, so we take the larger umber, i.e. Parallel with i distributio system colum i Tabe, we ca see i the colum of total lik, i.e.4 liks or 5 liks, i.e. he likset dimesio obtaied is 4 or 5 liks, ad we choose 4 liks for retrechmet. Example : Load distributio system used is 3 bit We estimate the bad coditio of the etwork, i is determied 0%, so Kl-max = 0% x 8 Kbyte/sec =.6Kbyte/sec If the likset traffic is 4.8Kbyte/sec (3 Klmax), there is ot 3 Kl-max i Table6 i the colum of 3 bit distributio system, so we take the higher umber, i.e. 4 Kl-ma Parallel with Kl-max i the colum of distributio system i Table6, we ca see i colum of total lik, 4 lik, 5 lik, 6 lik, 7 lik. It meas likset obtaied is 4 lik, 5 lik, 6 lik, 7 lik, ad we choose 4 lik for retrechmet. I calculatig likset dimesio, the likset traffic data used is eough if we use the data oly from oe directio, we do ot eed the data from two directios of, because the likset has two directios of trasmissio which respectively has the sama capacity of traffic. I figure, if the traffic fom E to C is bigger that the traffic from C to E, the data used is the bigger data, so the small traffic from the reverse directio ca be remaied trasferred. Cosequetly, the liket dimesio calculatio of CE is merely eeded by the traffic data from E to C. (Siemes AG, 994) 4.4 The Way to Calculate the ode Dimesio (Sigalig Poit Dimesio/ Dimesio) Oe of the ode which is fuctioed to sed ad receivig by calculatig the dimesio ca determie the capacity of. To calculate dimesio, we eed iput data of likset traffic i the uit of. trasfer capacity is obtaied by summig up all the likset traffic from, whereas receiver capacity is obtaied by summig up all the likset traffic to, so the calculatio of dimesio is merely doe by summig up (ITU, 99 ; Siemes G, 994) ad the formulas as follows: -X: (trasfer capacity) -X: (trasfr capacity) = traffic from X to Y..(8) Y= = traffic from Y to X (9) Y= For the sample i Figure, the calculatio of dimesio cab be see below: SEP-A: (trasfer capacity) = traffic from A to E.(0) SEP-A: (receive capacity) = traffic from E to A..() SEP-C: (trasfer capacity) = traffic from C to E.() SEP-C: (receive capacity) = traffic from E to C..(3) SEP-B: (trasfer capacity) = traffic from B to E.(4) SEP-B: (receivecapacity) = traffic from E to B...(5) SEP-D: (trasfer capacity) = traffic from D to E.(6) SEP-D: (receive capacity) = traffic from E to D.(7) SEP-E: (trasfer capacity) = traffic from E to A + traffic from E to B + traffic from E to C + traffic from E to D.. (8) SEP-E: (receive capacity) = traffic from A to E + traffic from B to E + traffic from C to E + traffic from D to E.(9) 80

9 The Way of Calculatig The Traffic COCLUSIOS To calculate the traffic ad etwork dimesio of CCS7, is by: - calculatig the traffic iter ed ode called SEP - calculatig the traffic i coectio lie iter ode called likset traffic - calculatig the dimesio of coectio lie iter ode called likset dimesio - calculatig ode dimesio called dimesio To calculate the traffic iter SEP, we eed two kids of data i.e. callig data ad sigalig data as iput data ad the calculatio by multiplyig callig data ad sigalig data To calculate likset traffic, we do by summig up the iput data i the shape of traffic iter SEP ad route arragemet, which the calculatio is by summig up every liks iter SEP routed to likset To calculate likset dimesio, we eed iput data i the sihape of likset traffic i byte uit, whereas the determiatio of likset dimesio is doe by usig Table 6, i.e. the table of maximum likset capacity toward the total lik To calculate the dimesio, we eed iput data i the shape of likset traffic i uit, the calculatio by summig up all the traffic likset set ad received by. 6. OTATIO CCS7 : Commo Chael Sigallig o. 7 ITU : Iteratio Telecommuicatio Uio CCITT : Committee Cosultative Iteratioal Telegraph ad Telephoe SEP : Sigallig Ed Poit : Sigallig Poit PST : Public Switch Telephoe etwork ISD : Itegrated Switch Digital etwork I : Iteleget etwork PC : Persoal Commuicatio etwork : Message Sigal Uit TC : Trasit Cetre : Sigallig Trasfer Poit : Local Exchage LT : Local Trasit Exchage S : Service Switchig Poit SCP : Service Cotrol Poit GSM : Global System for Mobile Commuicatio MSC : Mobile Switchig Cetre VLR : Visitor Locatio Register HLR : Home Locatio Register Kl-max : Maximum Capacity of Sigallig Lik Im : The Maximum utility level of Sigallig lik i ormal Coditio of etwork KLs-max : Maximum Likset Capacity : Total Lik i Likset y : All coected to -x P : Total Callig/sec PS : Success Callig Ratio (%) MS : Success Forward BS : Success Reverse MG : Fail Forward BG : Fail Reserve REFERECES CCITT: Specificatios of Sigallig System o.7 Yellow Book Vol.VI 6.98 ITU. Methods for Dimesioig Resources i Sigallig System o.7 etworks-e 73, Geeva,99 Siemes G. Plaig of Commo Chael Sigallig System o. 7 etworks Moche,