1. Classification by transmission medium

Wired communication: refers to communication in the form of transmission media such as wires, cables, optical cables, waveguides, nanomaterials, etc. Its characteristic is that the media can be seen and touched (open line communication, cable communication, optical fiber communication, optical fiber communication).

Wireless communication: refers to a form of communication in which the transmission medium is invisible or untouchable (such as electromagnetic waves).

(Microwave communication, shortwave communication, mobile communication, satellite communication, scattering communication).

2. Classification by signal transmitted in the channel

Analog signal: Any parameter of a signal (such as the amplitude, frequency, phase of a continuous wave, amplitude, width, position of a pulse wave, etc.) that can take an infinite number of values and directly correspond to the message, is sometimes referred to as a continuous signal. This continuity refers to the continuous variation of a certain parameter of the signal.

Digital signal: A signal that can only take a finite number of values for a certain parameter and often does not directly correspond to the message, also known as a discrete signal.

3. Classification by operating frequency band

Long wave communication.

Medium wave communication.

Short wave communication.

Microwave communication.

4. Classification by modulation method

Baseband transmission: refers to the transmission of signals directly into the channel without modulation

Communication method.

Frequency band transmission: refers to the modulation of a signal before sending it to the channel for transmission, at the receiving end

Communication methods with corresponding demodulation measures.

5. Classify according to the division of labor between the communication parties and the direction of data transmission.

For point-to-point communication, according to the direction of message transmission, communication methods can be divided into three types: simplex communication, half duplex communication, and full duplex communication.

The so-called simplex communication refers to a communication mode in which messages can only be transmitted in one direction. There are many examples of simplex communication, such as broadcasting, remote control, wireless paging, etc. Here, the signal (message) is only transmitted from the broadcast transmitter, remote control, and wireless paging center to the radio, remote control object, and BP machine, respectively.

The so-called half duplex communication method refers to the working mode where both parties can receive and send messages, but cannot receive and send messages simultaneously. Interphones, transceivers, and other communication methods are all in this way.

The so-called full duplex communication refers to the working mode in which both communication parties can simultaneously transmit messages in both directions. In this way, both parties can send and receive messages simultaneously. It is obvious that the channel for full duplex communication must be a bidirectional channel. There are many examples of full duplex communication in daily life, such as regular telephones, mobile phones, etc.