Communications system

A communication system or communication network is in communication engineering a name for the combined characteristics of the message traffic in a communication network. In a narrower sense, a communication system is a device or an infrastructure for the transmission of information. Communication systems to provide communications links between a plurality of terminals forth. Open communication systems allow permissive communication between all connected terminals. An important prerequisite for open communication systems is the standardization of interfaces and the logical functions. In data networks, this is achieved by the orientation of hierarchical architecture models with multiple standardized protocol levels. Generally accepted architectural model is the OSI model.

The term of the communication systems in particular, is used in the description of the properties and classification of various technical communications networks. Properties of communication relationships in networks are listed below.

Worldwide capacity

It is estimated that the world's technological capacity, information about ( analog and digital ) to receive technological networks of 433 ( optimally compressed ) exabytes in 1986 to 2,000 ( optimally compressed ) exabytes ( or 2 Zettabyte ) has grown in 2007. This is the informational equivalent of slightly more than 55 daily newspapers per person per day in 1986 and 181 newspapers per person per day in 2007. The vast majority of the world received information is still on ( unidirectional ) broadcasting and broadcasting networks instead. Only 3.5 % of the information (in bytes) is ( bi-directional ) telecommunications networks transmitted ( the vast majority of them on landline Internet access, about 96 % of it ).

Properties

Circuit Switched / packet-switched / news conveys

In the switching technology, there are three basic forms:

• Messaging - Message is delivered completely through intermediaries to the receiver ( for example, messenger / Ask)
• Circuit switching - exclusive line circuit between the communication partners (for example telephone network)
• Packet switching - message is broken into packets and transmitted to the receiver ( for example, Internet)

In the message-switched communications, the message is placed in one piece on a path from the transmitter to the receiver. If a message has a temporal extent, it is usually a progressive transfer. With circuit switching, a communication link is established between the end points, where all components take the same route. With packet switching, each part ( package ) is processed as a single piece, and can thus take different paths, for example, depending on the router selects the currently fastest way possible.

Connection-oriented / connectionless

Identifies the property that if a communication link has to be established before the message transmission. For connection-oriented communication systems, the communication is divided into three phases connection, communication, and connection termination. With connectionless services of connection setup and termination does not apply for multi- point connections, the actual message is placed in an envelope on which the destination of the message is recorded. A permanent line switching can remain connectionless.

Confirmed / unconfirmed

Identifies the property that if the sender can know that the message at the receiver is correct ( for example, within a time period ) arrived. In the mail this is the acknowledgment of receipt, for connectionless networks an acknowledgment message is usually sent back to confirm, and connection-oriented systems, a line test can be made at regular intervals, at their correctness error-free transmission of the data is assumed to be transferred in the meantime.

Synchronous / asynchronous

Identifies characteristics of the time consumption of the communication, especially in periodic communication links. For synchronous communication links the terminals run in the same cycle, the information coming through the transmission path to getting the right time. For asynchronous communication systems, messages may vary, long time on the road, and arrive interchanged even in different ways.

Temporary / static / permanent

In a temporary dial-up a communication link is established only when needed, dismantled after completion of the data transfer. In this case, no guarantee can be given that there is a sufficient resource for a connection. Static fixed connections a connection between the selected end points over an extended period of time is maintained even if it is not used. For permanent connections the endpoints of a connection establishment and termination can not be changed, eliminated.

Simplex / duplex - half duplex / full duplex

In simplex can only send one participant (implicitly unconfirmed connection). In duplex both parties can send and receive. With full duplex, participants can send and receive simultaneously, at half duplex is alternately sent or received.

Stationary / quasi-stationary / mobile

For stationary endpoints of the local reference is fixed. For quasi-stationary connections, the terminal is mobile, but it remains during the message transmission in the same place. For mobile connections, the communication is independent of the change of location.

Network design / topology

Describes the possible ways that messages can take in the communication network. The arrangement and properties of the paths is referred to as topology, in particular in relation to the construction of a computer network.

User referred / terminal relation

Identifies the type of addressing an endpoint of communication. If it is based terminals, the message is placed at the location of the device, and needs to be added by the user there. Wherein a personalized communication system, the person is called, regardless of the connection to the communication system.

Use / Classification

When using particular is the exclusive use of reserved for a connection to a shared connection for multiple users. The messaging can be configured as a broadcast to many unknown recipients, or allow a return channel an interactive circuit.

The classification of services can be done by parameters of the connection or the message. For example, by duration, time of day and distance of the connection, or by volume, weight, type of message form. Furthermore, the classification may include the possibility of the sender, receiver or to have both pro-rata pay per message, or settle by means of a lump sum ( flat rate).