What is Trunking?

Relay (Relay) is a transmission path between two switching centers. A trunk is a physical connection that carries multiple logical links. With the development of science and technology, the concept of relay is not only applied to wireless communication, the trunk of a network communication switch can also be called a relay. In daily life, we often need to chat with friends through the phone at home, or contact customers outside the company through the phone at the office. These calls are inseparable from the trunk.

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Relaying includes the following three forms:

l Analog trunk

The familiar fixed telephone line uses analog trunks. An analog trunk can only support one call at a time.

l Digital trunk

There is a big difference between the form of digital repeater and analog repeater. Telecom operators usually use optical transceivers to convert optical signals from optical fibers into electrical signals. An electric signal is a digital relay, which can support 30 calls at the same time, which is equivalent to the capacity of 30 analog relays. The digital relays currently in use are mainly primary rate interface (PRI) relays, also known as primary rate access (PRA) relays.

l IP relay

Provide users with access services via the Internet. There is no physical line between the two points, and Voice over Internet Protocol (VoIP) technology is used. After a user's IP PBX (Private Branch Exchange, private branch exchange) is registered with the Internet service provider's platform, a call can be made.

In wireless communication, the concept of relay refers to allowing a large number of users to share a relatively small number of channels in a cell, that is, to allocate channels to each user on demand from a pool of available channels.

In a relay wireless system, each user allocates a channel only when there is a call. Once the call is terminated, the channel that was originally occupied is immediately returned to the available channel bank.

According to the statistical data of user behavior, the relay enables a fixed number of channels or lines to serve a larger and random user group. Telephone companies use relay theory to determine the number of lines that need to be allocated for office buildings with hundreds or thousands of phones. Relay theory is also used in the design of cellular radio systems, with a compromise between the number of available telephone lines and the possibility that no lines will be available during peak calls. When the number of telephone lines decreases, the probability that all lines are busy for a particular user becomes greater. In a relayed mobile wireless system, when all wireless channels are occupied and the user requests service, a call block occurs or the system refuses access. In some systems, queuing may be used to save information about the user who is requesting a call until a channel is available.