Birth-Death Process In Telecommunication Traffic Engineering

If limited that condition transitions from Markov is discrete process only occur for conditions that timing is close, then will get random process that known as Birth-Death Process.

On birth-death process, focused is population problem. Total population is a random variable and obviously value from this process will be occur transition or condition change from n to n-1 if any ended condition (death), from n to n+1 if any just occur condition (birth). If in observation time interval there are no new conditions that occur or nothing ended, then the condition to believe not experience change. Explanation of condition change on birth-death process showed on figure 3.1.









Figure 3.1 Change condition on birth-death process

Birth-death process theory is very useful on telecommunication network analyze One telecommunication network can be modeling as one birth-death process, which total busy server that representation population, whereas “birth” to explain incoming call process and “death” to explain occupation ended process.

Markov Process In Telecommunication Traffic Engineering

Markov process is developed by A.A. Markov on 1907, that introducing practical simplified form to random variables that to produce a stokastik process. Simplified form from Markov is very match for process modeling on switching systems. Stokastik process mathematic formula from markov to definition as like this:

P[{X(tn + 1) = xn + 1}/{X(tn) = xn , X(tn - 1) = xn - 1 , ….. , X(t1) = x1}] =
P[{(tn + 1) = xn + 1}/{X(tn) = xn}]

Where t1 <>

Random Process Explanation In Telecommunication Traffic Engineering

One telecommunication network is to function as processing traffic that generated by the greater part of customer that connected to network. Customers that to do calling randomly, this mean when started, how long to happen, and when the ended, cannot known exactly. Call generating by costumers and event process on network or switching system got explained as one random process.

A random process or stokastik process is one process where the temporary value from one or more events are varies to time cannot ascertain exactly, but able to predicted with probability. Events in random process known as random variable. Loaded values in random variables from one random process is discretely or continuous.

Telephone traffic qualifying as one stokastik process, where total active customers and total busy server (occupied) simultaneously is random variables. In this telephone traffic case, random variables only load discrete values. Whereas temperature variation value that represented by a random variable result an experiment is sample for continuously value

In reality, it is impossible to estimating accurately total active costumers simultaneously in one moment. What can do is to make a prediction with one probability. Probability theory that generally used for random process approximation is Markov process and Birth-Death Process.

Basic Theory of Probability

Probability theory is one theory that learning problem from events that cannot predict first. Something as sample is telephone traffic, so that in telephone traffic engineering analysis and probability theory is a mathematic model of observed symptom.

Application of probability theory on traffic engineering, do with experiments (observation and data collection) and analyzing the result. Simple sample about it:

Experiments:
Observing telephone call between nine o’clock until ten o’clock
Sample space:
If
t = call time
Then:
S = {t, 9 < style="font-weight: bold;">Probability Standard
On calculation, usually used equally likely method and relative frequency, these both are basic method of probability theory.

1. Equally likely method, In this method, all sign have possibility to show that same.
2. Relative frequency method, Possibility unit standard show one sign connected with how often that sign show in several experiment. There is inclination, that relative frequency on a range fixed values, so that, there is long term stability relative frequency than that fixed sign.

Several Theorems

1. Addition
2. Multiplication
3. Bayes Theorem, this Bayes theorem giving one way to calculate, conditional probability from one sign to the other sign with calculating conditional probability from that the other sign to first sign.

Example:
Probabilities x line occupied and the other line (n-x) are free?
1
2
.
.
.
n

Every line:
Occupied Probability = p
Free Probability = q = 1 – p
Probabilities x line occupied and the other line (n-x) are free = px. q(n – x).
Total possibility occupied line x and the other free line (n-x): n ! / x ! (n-x) !
(That each have probability = px. q(n – x))
So, for occupied line x and the other free line (n-x):

P(x,n) = {n ! / x ! (n-x) !}. px. q(n – x)

This is Bernoulli distribution equation

What is meaning probability (line) occupied (or free)?
On telephone system, for every line:
p = occupied line probability, (several hour occupied in 1 hour)
q = Free Probability, (several hour free in 1 hour)

Observation with relative frequency:

| |
®| Dt |¬ ® t

Experiment: line observation every 1 hour, outcomes is:
occupied or
free

There is n = 1 (hour) / t (hour) time observation
Dt ® 0, then n ® -

Appearance occupied sign frequency = f(p)
Appearance occupied sign relative frequency = f(p)/n

= f(p). Dt = p (p + q = 1)

(The long time occupied line in hour per hour (busy))

so:

P(x, n) = æ n ö px. q(n – x)
è x ø

Several hour condition which occupied line x and the other line free (n-x), go on in certain time interval.

Random Variable and Probability Distribution
Random Variable, a quantity that the value formed by sign (outcomes) from one experiment.

Continue:
The long time occupied from one equipment (line) telephone is continuous random variable.

Probability distribution, random variable value that connected with the probability is shaping probability distribution.

Probability Function:
P( X = x ), where X is random variable and x a value that taken.

Continue:
Probability density function (p.d.f) and function distribution (d.f) or Probability Distribution Function (P.D.F)

Random variable T :
o p.d.f = f(t)
o d.f = P.D.F = F(t)










t
F(t) = P(T £ t) = ∫ f(u).du or f(t) = d.F(t) / dt

p.d.f : a standard from a density (closeness/concentration/density) from one probability on every point in continuous random variable time interval.

Grade of Service and Blocking Probability

On the loss system, the traffic is carried by network generally lower from real traffic that offered to network by customers. This overload traffic cannot proceed by network and will be loss traffic.

Total this loss traffic is an index from network service quality, is called Grade of Service (GOS), and definition as ratio between loss traffic and offered traffic to network.

Offered traffic itself actually is result from total call average from customers and average per call occupation time. Mathematically can explained with equation:

GOS = (A-Y)/A

Because (A-Y) = R = lost traffic

Grade of service = GOS = R/A

Smaller grade of services value, better services that produced. Example, if recommended that grade of services is 0,002, this mean there is two call from every 1000 call or call from every 500 call that offered customer is missing (cannot proceed). If, in one network condition, total customers is same with total server then GOS is same with zero, because every customers that will build a connection will always got success to occupation the server. Network system itself is non-blocking network.

Blocking probability definition as probability that all server on busy network system (dwelled). When all servers busy, then the system is no more to process incoming traffic. In this situation incoming traffic is believed to experience blocking.

Comprehension of GOS with blocking probability truly almost same, that is to explain about call size that cannot serve by network system. Main different between both is, GOS is a size with point of view from network side or switching system. GOS measured based on observation total call from customers that cannot loaded, whereas blocking probability based on observation busy server (dwelled) on switching system. To distinguish between both clearly, GOS usually named as call congestion (call jam, because showing part from call that rejected or unloaded) or probability loss, whereas blocking probability as time congestion (time jam, because showing part from time which all server or busy line).

Loss System and Waiting System

On one switching network, generally total line on bundle in on TO group will bigger from total line on bundle out on TS group ( m > n ). so, on condition that all server dwelled, that call that come (as overflow traffic) will block or cannot served, if that call :

1. Disappeared, then switching networks is work to comply with loss system.
2. Waiting until free line out available, then dwelled, then switching network is work to comply with waiting time system.

With note:
a. Limit waiting time
b. Total call that must wait is limit.

With offered traffic, carried traffic, and lost traffic.

Traffic Variation

In one telephone network, traffic load in one day (24 hour) very varies. This variation very ascertained especially by location or area factor where the telephone network exist and observation time (morning, midday, night, holiday, workday, etc).

Generally, for time interval midnight until six o’clock, network utilization is very low because is a rest time (sleep). Traffic peak is occurring in midday (ten o’clock until eleven o’clock) and after lunch period (fifteen o’clock until sixteen o’clock) because office hour bustle. Between seventeen o’clock until nineteen o’clock traffic relative low because on the way time period from work place to home. Domestic call peak generally occur after nineteen o’clock, after telephone costumer to stay in home and possibility of charge reduction from local telecommunication service provider.

As long as holiday or feast day (holy day), traffic form usually different. Generally, traffic peak occur around nine o’clock, at the same moment before telephone users leaving their home to go and next traffic peak is afternoon when they already to go home.

In one day, high traffic in 60 minute time interval, is called busy hour. 1-hour (60 minute) period between ten o’clock until eleven 0’clock, is busy hour. Because busy hour can varies between one central with another central depend on location and local community, then to calculating this fluctuation factor in switching network plan, CCITT already broken down into three busy hour type, there is:

1. Busy Hour, 1-hour continuous period that part of observation time interval, which the traffic volume or total call is higher.
2. Peak Busy Hour, busy hour each day or 1 hour every day where high traffic usually varies day to day, or total day.
3. Time Consistent Busy Hour, 1-hour period in every day, where the traffic volume average or higher total call in time interval in several day observations.

From several calls on one time period, usually not exactly all can success until shaping conversation connection. Several conditions, such as busy line, no answer from telephone that called, and blocking in trunk group or switching central, got to cause failure to build up that connection. One calls is believed success if already the answer from customer that called. Comparison between total call that success to all call, known as CCR (Call Completion Rate). Where as total call on busy hour known as BBHCA (Busy Hour Call Attempts), the important parameter to ascertain central process capacity.

The other parameter that usually used in traffic calculations is BHCR (Busy Hour Calling Rate), which definition as total call average by one customer (telephone) as long as in busy hour.

Traffic Intensity

Traffic intensity is a traffic density unit. Traffic intensity value explained in Erlang unit (Agner Kraup Erlang, Denmark, 1878-1929). Numeric value of traffic intensity is indicating total call average that simultaneously proceeds by switching equipment in time period. The mathematic formula is:

Traffic Intensity = Total occupation time from server/Interval time observation

To make easiest calculating how big the traffic intensity based on upon formula, there is 3-approximation method:

Approximation method –1:
Total call/occupation (on switching equipment system or server), that is C, observed as long as time interval T.

Approximation method -2:
If found C occupation as long as time interval T and occupation number i to possess occupation time as long as ti.

Approximation method -3:
If C = Total call (occupation) per time unit
= Average call rate
tr = Average occupation time

Then, traffic intensity: A = C . tr

Switching Network Characteristic

1. Availability = k, Is total bundle-in that can reach line-out.
2. Full availability bundle and Limited availability bundle

To make easiest, network form will simplified such as showed on figure 1.3, which:

• TO Group will consist of line in with m line
• TS Group (server) will consist of line out with n line that total line out match with total server.
• Switching networks equipment; include set relay, register, etc, represented by “g” box.

Figure 1.3 Line in and line out on switching network

1. If every bundle from line out can reach by every bundle from line in, then that bundle is called full availability bundle.








Figure 1.4 Illustration of one full availability bundle

2. If only half from out bundle can reach by line in from bundle in, then that bundle is called Limited availability bundle.







Figure 1.5 Illustration of one limited availability bundle.

Telecommunication Switching Network

A switching network will connect group of trunk opering (TO), as build up connection (telephone traffic) path request, to Trunk Serving (TS) or server. This TO and TS form as customer line, trunk between central or switching equipment, and if needed, also form as equipment generally to build connection.

TO that functioned to send build up connection request (telephone traffic) to switching network will shaping group TO. Meanwhile servers that receive and to forward on build up a connection is request for one route switching will shaping group TS.

One server on busy state if already happen a connection through switching networks between one TO and that server. In this case, traffic that carried by TO group will form as calls that will using one server, which one call that succeeded shaping connection (from one caller customer to called customer) will to dwell one server.

Time period which one server on busy state and cannot interrupted to do one switching job, is called Holding Time.

Complete definition of holding time is total time utilization/occupation one switching equipment by one call, start from the customer pick up telephone (hook off), or when central start (seized), until end connection (cleared) customer putdown telephone (hook on).









Switching network as conversation path network














Switching network as network connector
Figure 1.2. Simplified switching network configuration

Telecommunication Network Structure

Structure or telecommunication network form is very varied, especially confirmed by need and local demography. On the first telecommunication network development, there are two basic network forms, that is mesh network and star network. At this moment already develop to the other network forms, are bus network, ring network, and tree network.

If on n network station equipment (telephone or central), every station direct connected to each station with stand-alone line (figure 1.1 (a)), then the configuration is called mesh network. On this network, every station needs n-1 line to connect to every station, so that the total line that need on mesh network is 1/2n (n -1) line.






Figure 1.1 (a) Mesh

Mesh network practically is match for system with n total small and short lines, example, for little system that serves several telephones in one office. If n increase (big enough) and the lines become long, using mesh network became very expensive. Example, system with 10.000 customer stations will need at least 50 million lines.

On telephone system, two-way communication between costumers and central that to be connected each other and this two-way conversation must execute in the same time. This case only performed if on network found one station that function as switch central (telephone central), terminal all customer telephone line. Network with this configuration, is called star network. Such as showed on figure 1.1.(b).







Figure 1.1. (b). Star

If a customer far away from central or coverage area is very large, then using star network became inefficient economically because a line become long and cost line will be expensive. For handling this condition then need implemented combination of mesh network with star network, such as showed on figure 1.1. (c).






Figure 1.1. (c). Mesh & Star

Beside a mesh network and star network, all equipment station can also connect to one single line, shaping a bus, such as showed on figure 1.1. (e), or shaping a ring or loop such as showed on figure 1.1(d). Bus network and ring network form used on data communication with data transmission performed via jointly line with high-speed then speed on each individual station (terminal). Example application that using bus network or ring network is LAN (Local Area Network).





Figure 1.1 (d) Loop




Figure 1.1. (e). Bus

If network coverage area already very large (one country or more), then network form became very complex and generally invented become hierarchy, and is called tree network.






Figure 1.1. (f). Tree

Basic Principle Telephone System Plan

Generally equipments on telephone system must be planned perfectly so that as long as high traffic period or busy hour:

1. Every customer that call (build connection) can serve with big enough possibility.
2. Only for the smallest part of Customer request that can not served quickly
3. Total switching equipment that work for handling telephone traffic on busy hour as little as possible.

Based upon basic principles, found a solid connection between total supplied equipment with possibility succeeded shaping a connection.

So much the total switching equipment that supplied so much the fulfilled possibility of customer request to shaping a connection.

Charging between Telecommunication Network Operator

In order to the telecommunication coverage as large as possible, between different operator networks is need to interconnect. This interconnection can happen between networks that to operated on the same country, or networks inter country. The charging between different networks operators also need arranged and matched. The financial settlement method between the network operators is known as accounting settlement.

Accounting settlement invented based on total use over time period that given, and paid from origin call network performed direct to all network operators. Settlement method can do with simple settlement or cascaded settlement. On figure 4.7 is showed accounting settlement model with both methods.








Simple settlement (direct)









Cascade settlement
Figure 4.7 Acutance settlement model between network operators

Accounting settlement with simple settlement method (figure 4.7.(a)) only possible to do if network provider A to know definitely a path that used by calls yang to aim at network C, after to pass network B. Example, If available route from network B to C via network fourth, that is E, then simple settlement method become impossible because network provider A cannot calculating divide financial on settlement with network provider E. This reason that caused always to used cascade settlement method, that model showed on figure 4.7 (b), which in this method performed proportional transit settlement and consecutively according to cascade.

Accounting settlements depend on totally used payment time that measured. This payment time, for every call is same with total time that used since call got respond until end of conversation. Settlement counted with multiply total time paid, that total with acutance cost that total already agreed first between network providers that connected each other. Several parameters that usually used as reference to ascertain acutance settlement cost is:

1. Distance and call destination
2. Service type
3. Call duration
4. Time call
5. Switching equipment type
6. Route
7. Etc.

That currency used for payment from origin operator network to the other operators, ascertained based on agreement between network providers. If happen difficulty, payment can do with standard rate that recommended by CCITT Seri D.

Charge Variation In Telecommunication Network

Traffic that proceeds by telecommunication network, in one-day full operation, will have variation density. Switching equipment plans and network invented based on traffic estimation on busy hour.

Outer busy hour, for the greater part of equipment that available in the network is usually in idle condition.

In order to traffic variation density can distributed flatten, telecommunication services provider usually applied variation charging on a certain hours in one day. So the costumer can choose the right time to call.

This charging variation method, generally with speedup or slowdown duration per meter pulse, even though pulse cost is constant. Seed up time duration between pulse usually do on busy hour, so that costumer that call on that time the pulse meter will move quickly from the standard time, and for call time duration that is same will charge with a high charge then if that conversation performed in another time that speed between pulse is not accelerate. With this method hopingly un-important conversation can postpone, performed in outer busy hour.

Delayed time duration between pulse usually performed on outer busy hour, example night, dawn, or weekend, so that costumer who call in that time the pulse meter will move slower then the standard time, and for call time duration will charge lower then if that conversation performed in another time that speed between pulsed not slow down.

This charge variation is usually only for local connection type or trunk, is not for international connection. Speed variation between pulse that confirmed, between telecommunication services operator or inter country usually also different, in spite of generally model that a lots used is such as that showed on table 4.1.

Day period Rate between meter pulse
06.00 – 18.00 T
18.00 – 21.00 3/4T
21.00 – 24.00 1/2 T
00.00 – 06.00 1/4T

Table 4.1 Generally charge variation model (only as sample)

For long distance connection, besides formed by time call, charge variation also formed by distance between caller and who called. The longer a distance, shorter duration between pulses. Limits distance it self usually already formed clearly by local telecommunication services provider.

Charging Method in Telecommunication Network

Charging system that used by operator to customer can do with several methods. Three methods that a lots used is:

1. Service charges
2. Flat rate charges
3. Combination.

Services charges method is the charging methods that include charging group that depend on duration dependent charging. Component cost that charge to customer with this method is basic rate that total is constant every month (as costumer rate) and total call charge is depend on utilization.

With charges services method, central equipment must completed with metering register equipment for every customer. Conversation pulse meter will increase every succeed call or succeed connection, even though increase or speed of increase depend on parameter:

1. Network type that used
2. Call time duration
3. Data volume that carried
4. Telecommunication distance (from caller to called).

The other factor that also influential on how big charges service are:

1. Additional services on build connection, i.e. operator assistance.
2. Call time, on busy hour period or outside busy hour.

Flat rate charges method is charging method that include on charging group that not depend on time duration (duration independent charging). With this way total cost that charged to costumer is constant every month, so that on central side is do not needed metering pulse equipment.

This method is very favorable, especially for customer that always call with very high intensity or frequency call. In order to go through a loss, the operator is usually charging high flat cost to customer.

On flat rate charging system, costumer usually has an inclination excessive call, because of that the local central should be designed to able handling a high traffic level.

Combination method is charging method that combines charges method services and flat rate. On this method, for total call or pulse every month (or per period), costumer uncharged. Then after total pulses exceed a fixed limit, call will be charge.

Charging System In Telecommunication Network

Supply and operating the telecommunication system equipment is needed very high invests cost. On first step, this cost guaranteed by (operator) telecommunication services provider, then on operational step this cost also to charge to customer that using telecommunication service. Cost to charge to customer usually form as:

1. Connection cost to network
2. Equipment rent
3. Utilization or succeed conversation

Cost connection to charge to costumer because operator side to notice costumer side also have obligation to pay by installments half of invests that already spend for supply equipment.

Rent equipment cost is the cost that charge to customer for equipment used, example rent terminal equipment (operator telecommunication network equipment) or rent cost that connected customer to central so that every moment is ready to use. This cost is constant and confirmed by operator side.

Utilization cost is charge to customer for succeed connection or succeed call. Total this cost is depend on total call, how long the conversation from that calls, and call type (local, trunk, or international).

On competition era such as right now, where the telecommunication service provider is more then one, then to still get to search new costumer the connection cost always to make unclear (to seem very small or none) but truly added to equipment rent cost or utilization. That the end feel by customer relative become very high.

Numbering On Local Telecommunication Network

Call number in every telephone (terminal) on one local network is uniquely and to consist of central identification number which that telephone is connected and added customer identification (line) number on that central. Total digits for one costumer number depend on customer density and customer network condition where the customers exist.

CCITT recommended that a total telephone number in every country is 11 digits. In Indonesia, 2 digit used for country code, the number is “62”, 9 digit is for area code and telephone calling number (local number). Because area code in Indonesia to consist of 2 or 3 digit, then total digit maximum for local number in Indonesia is 7, that is only for big cities like Jakarta, Surabaya, Bandung, Medan, and Semarang, that only have 2 digit area code. Example local telephone number (calling number) planned, showed simply on figure 4.5 and 4.6.









Figure 4.5 Numbering on one local central


























Figure 4.6 Numbering that involved several local central.

Area Code Allocation In Telecommunication Network

In numbering plan, area code allocation in one country can do with two ways, which is random or systematic technique. On random technique, area code numbering can apply without follow a rule or random and is not bind on available network form. Meanwhile on systematic technique, numbering can apply with rule that already decided and bind on condition or available network form. For more understanding different between both techniques, this explained characteristic from each technique on area code numbering plan:

Random technique:

1. Numbering can apply with randomly
2. No need of backup numbering
3. Not bind on network form (mash network or star isn’t problem)
4. Because factor on (b) and (c) up, then area code numbers plan become easy. Hard to implement.

Figure 4.3 Example randomly area code allocation

The random numbering seems easy. The hard way is implementation because there is possibility that the locations with short numbering area code actually have a long distance geographic (Example city A and B, E and F), on the other hand areas with area code that far from another number actually geographically is closer. So that, register equipment to shaped long distance network must first receive all digit or area code information in order to confirm where the truly destination connection long distance that will do. Off course, this condition will influence speed of routing process and for calculate charging will needed equipment that more complex.

Systematic Technique:

1. Numbering bind on rules that already confirmed, especially on network form
2. Need to think and planed backup numbers for possibility of network development, so that on the planning become more difficult and more carefully.
3. Because the plan is already planed accurately, then on technical execution will become easy.

Example area code numbering allocation with systematic technique represented by figure 4.4, which showed that every digit from area code number already contain information about destination area so that will to simplify preparation routing process. In this case, numbering area code allocating plan bind on network that hierarchic formed.













Figure 4.4. Area code allocation systematically

Example of country that applies numbering area code with systematic technique is Indonesia, although on development actually combined with numbering random technique. But because at this moment almost for the greater part of central that operate in Indonesia is digital central, then numbering allocation with random technique not anymore become a problem.a

Numbering Plan In Telecommunication Network

On numbering plan for one network in one country, there 3 ways that usually used, that is:

1. Opened numbering
2. Closed numbering
3. Combination numbering

On opened numbering system, area code only used when to perform long distance connection (trunk), event though to build connection with the local customer, just to dial the customer number destination. This numbering system usually used by country that:

• Large area
• Comparison the local connection is more higher then toll/trunk connection.
• Local area limits that one with other is clear.

The example of country that using opened numbering system is Indonesia, which to perform long distance call, the caller first to dial digit “0”, then followed area code and ended with destination customer number.

Example A that living in Bandung want to call B that stay in Jakarta with telephone number 8602345. The number that dialed by A is 021-8602345, where first digit “0” to represent prefix trunk and digit “ 21” is area code Jakarta.

On closed numbering system, area code is direct (joined) combined with customer telephone number. So that on this system there is no different between local connection and trunk, because every call must always to dial code area (without trunk prefix), then followed with customer telephone number. Closed numbering usually used by country that small area so that no need the trunk connection. Example, the country that using this system is Singapore.

International Telephone Numbering System On Telecommunication Network

System or international telephone numbering plan is definition by CCITT E163 recommendation, with explained principles that to be connected with numbering for general telephone network. This numbering system aimed to ensure the allocation of a unique number (digit row) to identification every individual telephone line that connected to worldwide telephone network. In this case, that recommendation is not to regulate individual numbering plan in one country, just allocating place for the amount of digit number that can be used on numbering system in national network each country. With this flexibility, then every national network operator in one country to be able to build a national numbering system it self, that considered optimally for condition or country necessity it self

Three row numbering system that generally adopted by operator in mostly country is that interlaced with call for international connection, toll or trunk, and local connection. To build up a connection on the local connection performed directly using the telephone number customer as an address. To build up a connection on the long connection (trunk) and the international connection, performed with using area code (city) or country code first generally is called prefix code, and then added with destination telephone number customer.






Figure 4.1 International telephone numbering system structures

International prefix: to consist of combination 2 digit number, usually “00” (prefix definition is addition number, as area code or country code, on customer calling number/customer local number)
Country code: to consist of 1 until 3 digits, to represent identification code on one country to build up the international connection.
Number national: to consist of prefix area or code area and customer telephone number. This number concluded by local administration provider.

Generally, international prefix that used in all country in the world is “00”, where as for country code concluded according to CCITT E163/E164 recommendation based on district allotment or zone, show on table 4.2.


Zone Region
1 North America
2 Africa
3/4 Europe
5 South America
6 Far East Asia
7 USSR
8 Far East Asia
9 Middle East & Central Asia

Table 4.2 the world telephone numbering zone
(CCITT E163/E164 recommendation)

Indonesia, Singapore, and Australia are example country that to lie on zone 6, so that code country started with digit “6”. Indonesia code country is “62”.

Example, if costumer from foreign country want to call costumer in Bandung which the telephone number is 5402021, then number that must to dial completely is 00-62-22-5402021, which the number “22” is Bandung area code.

Numbering System On Telecommunication Network

Two parts that very important on telecommunication network plan, is numbering and charging. Numbering system plan is to aim at identification uniquely every user (terminal) that connected to telecommunication network. This numbering system become a part that very important for routing plan on the network, also for administration process, among other things is to charging administration until to users level that severally, based on numbering system, to posses identification or unique address.

Numbering system generally already recommendation by CCITT to adopts by every country. With that recommendation than to make possible cooperation operational telecommunication inter country, so that between users in that countries to be able to build telecommunication connection each other, because on that recommendation also explained numbering system (address) until level terminal equipment (users).

CCITT Recommendation classified the numbering system in to four numbering scheme for different network type, that is:

1. E163 Recommendation is a system or numbering plan for international telephone services.
2. E164 Recommendation is system or numbering plan that developed from E163 recommendation, to fulfill requisites of ISDN era (Integrated Services Digital Network). On this recommendation applied system with longer total number and change several procedure.
3. X121 Recommendation is system or numbering plan for international packet-switched network.
4. F69 Recommendation is system or numbering plan for international telex service.

Principle from each that numbering scheme basically is same, and for adopts in one country, numbering system is possible to modification or matched with local condition.

Major Telecommunication Network 2

With so much the telecommunication services variety, then ISDN now to appear as a major telecommunications network. ISDN is a single network that to be able for handling multimedia services such as voice, data, video and facsimile. Key of ISDN is a service digitalization, transmission, switching and signaling. In this case computer part become very dominant.

We now at this moment the main and larger international communication infrastructure is telephone network, because of that, ISDN planed to perform design develop and telephone network plan that already to be available right now to the system with end-to-end digital connectivity. Of course that change is not easy and cannot be happen quickly. At this moment, although the digital telephone system already many implemented, but because the investment is expensive, then many country to perform change step by step. So that ISDN until a couple of year in the future must still to operated side by side with available analog telephone network. All this directly to show that standard for ISDN must produces as good as possible before implemented. That aspect already recognized by CCITT and the first recommendation about ISDN recommended on 1984, then perfected again on 1988.

Perhaps ISDN to represent important example from contribution of computer technology to telecommunication, and this could be to represent very important development as result from combining between computer technology and communication. Utilization computer with big scale on ISDN already to spur on created Intelligent Network (IN) concept that programmed for adaptively, algorithmic, clever, responsive, and intelligent. Example ability that maybe to perform by IN is usually known as “real time translation machine”. A telephone conversation that the original language is in Japanese language can be hearing directly in English language in the receiver and on the contrary. A telex that sends in Indonesian language from Jakarta will be delivered to Solo in Javanese language. That example, although at this moment still to consider as excessive imagination, to guess will possible to realized on 21-century coming up.

Telecommunication network already to realize rapidly grow at last 150 year and will keep grow to larger services on better form in the future century. Information form that will show in the future is very depending on telecommunication development and need a services variety on that moment. To guess that millions dollar will invest by many countries in two-decade coming up for development the telecommunication system facilities. We apparent will soon to go in to high tech telecommunication era.

Major Telecommunication Network 1

Telecommunication network can be categorized according to wide geographic that covered. Big city usually have high-density users and heavy traffic per user. Telecommunication network characteristic on big city to consist of lots of local central and one with the other have close distance. Network designed for that condition, usually known as urban network or metropolitan network.

Rural area have characteristic with low density, user that spread everywhere on large area, low traffic per user, just only have one or two central for handling users in wide area, long distance between user and central, bad condition environment and also less to support infrastructure facilities. That area must served by rural network.

Long distance network or Toll functioned as backbone interconnection a metropolitan network and rural network. That networks to support communication intra-country, inter-country, and inter-continent. In the telephone network context, urban network and rural network usually is called local network. But on data network context, local network form usually a network in building or campus.

Right now the gigantic telecommunication network is Public Switched Telephone Network (PSTN) or known as POTS (Plain Old Telephone System). Right now there are more then 500 million telephone in the world and the distance cable for that telephone network is to guess already to reach more than 12 time distance between earth and sun. Speed of growth value exactly already increased. Right now that growth speed has far away from computer industry.

Telecommunication industry and also the services in one country usually government authorized, but development already to show that public sector also can to involve actively. In US almost for the greater part the service provider industry and telecommunication industry is public sector authority. Monopoly by a government usually to covers the pos sectors, telegraph, and telephone. Committee or government department is to authority that sector usually known as post administration, telegraph and telephone (PTT).

With so many agency who involved in to supply telecommunication service, then clearly need a world scale capability guarantee so that between the networks got to be connected each other. This coordination performed by International Telecommunication Union (ITU) is part of United Nation (UN). ITU have 3 main groups, anything such as handling telephone and data communication. This group known as Committee Consultative Internasionale de Telegraphique et Telephonique (CCITT) or International Consultative Committee for Telegraph and Telephones.

Telecommunication Evolution 3

The modern telecommunication systems as one group for the greater part the electrical communication system or optical communication system with point-to-point configurations.

Although that system has ability to carry electric signal and optic, carried information is not always on both that signal formed. Example, human voice signal, first needs to convert to electric signal or optic, before carried by a communication system. Transducers are needed for converting. Using optical source to need electric signal as input, and optic detector will produce electric signal as output. In this case, original signal first converted to electric signal and then to optical signal on moment to go into optical communication system and in this optical signal receiver is converting back to electric signal before original signal reproduce. A media need to carry that signal. This media known as channel. Example, the outer space, cable (copper or fiber optic), etc. To be connected with satellite on the electric communication system. These channels, generally to have the character of loss and easy or inclining get noise from outside that will reduce carried signal information value. Different channel will to show different characteristic and influenced by disturbance with different degree. So, transmitted information signal via channel must exactly match with specification used or condition of channel, so that basic losses effect from channel and disturbance can protect constantly on accept level. And the signal can to reach destination with accept level (still to comply with receiver equipment specification).

Channel characteristic and signal from telecommunication system individually on one telecommunication network very varies. Example, communication system between users and switching system commonly using two wire copper cable as channel, even though communication between switching system usually using coaxial cable, fiber optic, or along space (radio frequency wave) as channel. Equipments type that used as terminal will to ascertain characteristic of carried signal between terminal end and switching system. Example, the electrical characteristic from teleprompter signal, is totally different from telephone signal. Services type on telecommunication network increased and growth. Severally to posses specification and specific used, and operated without hanging each other. Example:
Telegraph network
Telex network
Telephone network
Data network

Telephone network application it self now already growth, not only for processing telephone information (voice) but also data, example application facsimile, Internet, etc. So that to become blur different between telephone network and data network.

If we see from terminal equipment side, telephone equipment right now not only just for processing voice information, but also data information even picture/graphic. To fulfill users flexibilities, telephone at this time already mobility, so that to make easier telephone service users to conversation or data exchange anywhere and anytime.

The telecommunication network form is more and more complex, so that management and also maintenance will be very expensive, especially for multiple networks. So that to emerge an idea for designed single network that can handling all service. If all information or specific signal form from that services can convert to a similar form (standard) on digital domain, then a network that have ability to transports digital signal will handling multitude of service. This idea right is now already to bring forth the evolution to Integrated Services Digital Network (ISDN).

Telecommunication Evolution 2

On first development, the switching systems have the character of manual and oriented to operator. Limitation of operator ability for handling that systems already changed and very quick development to created automatic central system. This automatic switching system can classification as electrical-mechanical system and electronic. To belong to electrical-mechanical switching system is step-by-step system and crossbar.

Step-by-step system known as Strowger switching system according to discovered name, which is Almon B. Strowger. Control function on Strowger system formed by circuits as switching element on the system.

Crossbar system has subsystem that hard-wire control using relay and latches. That subsystem has limited ability and that fact virtually causing impossible to modification for to fill up with extra functions.

On electronic switching system, control function by computer or processor, that system namely Stored Program Control System (SPC). New facilities can fill up with changing control program.

Switching formed which used on electronic switching system can be space division switching or time division switching. On space division switching, one path dedicated to build connection between caller user and called user as long as connection (conversation). The Space division switching is also using the Strowger system and Crossbar technique. With the other word, one switching crossbar system with SPC is qualification as an electronic central.

On the time division switching, speech signal value already sampled, transferred to be certain interval. Time division switching formed as analog or digital. On analog switching, sampled voltage level, transmitting (without change or without coding again), whereas on switching digital, the signal changed first to binary code and then transmitted. If values transferred which already coding as long as same time interval from input to output, the technique is called space switching. If those values stored and transferred to output on next time interval, the technique is called time switching. A time switching digital can design with using a combination from space switching and time switching technique.

A users on around the world clearly impossible to connected to the single switching system. If not formed as gigantic switching system, which also to cover air as media and every user have direct access to the same system. Although satellite communication systems can reach coverage for the greater part of earth surface, that system capacity still limited. Main part from a telecommunication network right now still mainland network, where a users or terminal connected to switching system via copper cable with the endorsement that based on technology aspect, signal transfer along two wire cable only can do correctly if the terminal distance is only on several kilometer from switching system. With using to the amount of stand-alone switching system on locations that geographically correct, communication abilities can apply between users on same location. Although however that may be, so that users that to live on different location can communicate, then switching systems need interconnecting to form a network.

Connect link between switching system namely trunk, and connected switching system to users is called subscriber lines. Total trunk got variation based on couple from switching system and firmed by basic traffic between those switching systems. With the switching system increased interconnection between them to complex. That problem must be solved among other thing with using a hierarchy structure to all that switching system.

Telecommunication Evolution

Based on history, telegraph signal transmission via cable is first modern technology telecommunication system that to develop. Telegraph introduced on 1837 in England and 1845 in France. On March 1876, Alexander Graham Bell demonstrating telephone equipment and possibility for development telephone system, example telephone system with distant voice transmission. This important invention of Alexander Graham Bell is very seldom and basic of telephone system development right now.

Graham Bell is demonstrating point-to-point telephone connection. On that network, costumer who wants to call can choose available link for build one connection with called costumer. So that before information trading started a costumer who called understands will be called then on every link need a signaling. If costumer who called is in busy state (talk), one indication to explain that state also must be given to costumer who calling with using signaling method.

Generally can explained that for n terminal, need n(n-1)/2 link. Let’s see n terminal on several condition/destination. For connecting first terminal to all terminals, we need (n-1) link. On that condition, second terminal already connected with first terminal, so that for connecting to other terminal need (n-2) link. For third terminal, need (n-3) link, and so forth. So that total link, that is:

L = (n-1) + (n-2) + ….. + 1 + 0 = n(n-1)/2

Network with point-to-point link between all terminals known as fully connected networks. The total link needed on one fully connected network will be very big with moderate change from n value. Example, we need 1225 link for build full connection between 50 costumers. The consequence is, used practical of Bell discover on one big scale network will to appear with request not only in telephone equipment and two wire cable but also to appear with need of switching system or central.

With deploying switching system, costumers not connected directly to the other costumers, but connecting to switching system, so that if one costumer want to communicating with other costumers, then on that switching system will build a connection between them. On that configuration, all costumers only need one link to connected to switching system, so that total link equivalent with total costumer who connected to system

On utilization switching system, signaling need to build or release one connection. Signaling must acquire enabling switching system for detection is that a costumer who called on busy state? If yes, indicating to costumer who calling. Formed function by a switching system to build and release a connection known as control functions.