Teletraffic

Telecommunication is basically needed for human being, mostly, in modern life. The use of telecommunication in modern life not only for conversation but also for information exchange. Telecommunication can be formed into voice communication and data communication. In modern era, there are a lot of examples of telecommunication devices like pager, cellphone, internet via computer, etc. From time to time, technology development influences work of telecommunication devices. The technology development make telecommunication faster and better then before. Like car traffic on the road, telecommunication has its own traffic which influence the final result and perfection of its own technology. And traffic of telecommunication is known as teletraffic. Teletraffic has 3 elements which determine the smooth of teletraffic. Those are Quality of Service, Traffic Load, and System Capacity.

Teletraffic, means traffic on the long distance communication. There are wired telecommunication and wireless telecommunication. Mostly, telecommunication uses wire for the transmission medium. Telecommunication has a traffic, and traffic in telecommunication is known by teletraffic. Traffic in telecommunication is divided into 2 categories, voice telecommunication and data telecommunication (picture, video). For instance, traffic can be formed into calling which must be connected into telephone network, package must be routed into data network, request for the web server, etc. Traffic in telecommunication is made by system user. Basically, in a system of teletraffic there are incoming traffic and outgoing traffic.

The first element which determines telecommunication traffic is traffic load. Simply, traffic load is input from telecommunication traffic, or we can say the traffic load is the first process in teletraffic. The example of traffic load on telecommunication are the number of whole users, the number of active users, the number of calling demand, and the number of SMS request –for data telecommunication. Voice telecommunication uses Erlang units, the Erlang is named after the Danish telephone engineer Agner Krarup Erlang. For example, calls average in the home is 0.5 hour (for a hour), and there are only 1 traffic channel. So in the traffic load in that system is 0.5 Erlang. If calls average is 1 hours, the traffic load become 1 Erlang. While on data telecommunication uses kilobyte (KB) units (1 byte = 8 bit).

The second element is system capacity. System capacity is a response to traffic load which has and will happen. System capacity including data or voice(frequency) receiver, controller station and also temporary storage. Telecommunication system uses queuing theory which basically also uses FIFO (First In First Out) basic theory. For example, when we send an SMS, at the same time also has other SMS delivery. So that, the first who sends SMS will get the first service. The queuing theory will beneficial if there are a lot of active costumer. The bigger capacity from the system which is used will influential to delay time.

The final element which determines the smooth of teletraffic is Quality of Service or known by QoS. QoS is a measure of the quality of the signal transmitted over the RF (Radio Frequency) channel. In some systems, the QoS measurement is used to dynamically adjust operational parameters such as transmitter power levels and coding rates. For several cases, sometimes QoS is known by Gos (Grade of Service). QoS and GoS often uses for clarification one to another (often exchange). QoS’s definition is the collective effect of service performance which determines the degree satisfaction of a user of the service (ITU-T recommendation E.800). There are 4 aspect on QoS :
• Serveability.
• Support Services.
• Operability, and
• Security.

QoS parameter is obtained based on user perspective.
From the three elements above, there are relationship which influence each other. In teletraffic, the three elements can not be separated. Therefore, a relationship from traffic load, system capacity, and QoS determines the smooth of teletraffic.

And for the relationship of the three teletraffic elements –between System Capacity and Traffic Load, Quality of Service and Traffic Load, also Quality of Service and System Capacity.

Evolusi Mobile Communication

Semakin berkembangnya teknologi semakin memudahkan manusia dalam melakukan pekerjaannya, hal ini juga terjadi pada dunia komunikasi. Yang mulanya menggunakan kawat (wire), saat ini telah tergantikan dengan komunikasi tanpa kawat (wireless). Sehingga semua orang dapat melakukan komunikasi jarak jauh (telekomunikasi) dengan bebas bergerak tanpa terganggu kawat sambungan --biasa juga disebut mobile communication.

Telekomunikasi memudahkan manusia dari masa ke masa. Terdapat beberapa generasi dari sistem telekomunikasi itu sendiri. yang saat ini ada di Indonesia (3G-baca triji) merupakan generasi ketiga dari sistem telekomunikasi itu sendiri.

Generasi pertama dari sistem telekomunikasi adalah sistem analog, AMPS (Advance Mobile Phone System) merupakan contoh generasi pertama sistem telekomunikasi yang dikembangkan oleh Bell Telephone System. Dimana sistem tersebut menghubungkan satu user dengan user yang lain menggunakan teknik FM (Frequency Modulation) analog. Generasi pertama yang lain adalah
- Narrowband AMPS (NAMPS)
- Total Access Cellular System (TACS)
- Nordic Mobile Telephone System (NMT-900)

Perubahan dari generasi pertama (1G) menuju generasi kedua (2G) merupakan perubahan dari sistem analog menuju sistem digital, dan juga peralihan dari PSTN dan ISDN menuju mobile communication. Alasan lain perubahan sistem menuju 2G adalah kurang berkembangnya jumlah pelanggan serta kurang kompatibelnya 1G. Pada 2G penggunaannya adalah untuk voice (suara), dengan data rate 9,6 - 14,4 kbps. Keuntungan 2G yaitu menggunakan teknik pengkodean berdasar pada teknologi digital. Teknik multiple access (akses jamak) seperti TDMA (Time Division Multiple Access) dan FDMA (Frequency Division Multiple Access) serta CDMA (Code Division Multiple Access) digunakan pada sistem selular 2G.

GSM (Global System for Mobile communication) merupakan sistem 2G yang menggunakan teknik FDMA dan TDMA. Sedang CDMA IS-95 merupakan sistem 2G yang menggunakan teknik CDMA.

Sistem Selular generasi ke-3 (3G) didesain untuk mendukung layanan wideband seperti akses internet, transfer gambar dan video selayaknya fixed network. Contoh dari 3G yaitu WCDMA (Wideband Code Division Multiple Access) yang dikembangkan dari sistem GSM, dan CDMA2000 yang merupakan pengembangan dari CDMA IS-95. Dan untuk sistem telekomunikasi generasi keempat (4G) merupakan sistem terbaru yang memiliki kemampuan akses lebih cepat dibanding 3G, dan biasa disebut LTE (Long Term Evolution).