multiplexing technology

Multiplexing refers to a mechanism in which two or more users share a common channel.Through multiplexing technology, multiple terminals can share a high-speed channel, thus achieving the purpose of saving channel resources. Multiplexing is divided into three categories: frequency division multiplexing, time division multiplexing, and code division multiplexing.
1) Frequency Division Multiplexing (FDMA)
The transmission band is divided into N parts, each part can be used as an independent transmission channel, so that in theThere can be N sessions of channel information transmission on a pair of transmission lines, and each session of channel information only occupies one frequency band.Frequency division communication is also called carrier communication, which is the main means of analog communication
2) Time division multiplexing (TDMA)
Time division of a transmission channel to transmit several speech channelsInformation,.Connect N Hualu to a common channel, and assign a period of time to use the channel to each device in turn according to a certain order.When it is a device's turn, the device is connected to the channel to perform the operation, and at the same time, other devices are disconnected from the channel.As soon as the designated use time interval arrives, the connection between the current device and the channel is cut off through the time-division multiplexing switch, and then it is connected to the next device and channel.Time division communication is also called time division communication, which is the main method of multiplex communication of digital telephone, so PCM communication is usually called time division multiplex communication
3) Code division multiplexing (CDMA)
CDMA technology is not a new technology. As a multiple access scheme, it has been successfully used in satellite communication and cellular phone fields, and it has shown advantages over other technologies.However, due to the bandwidth limitation in satellite communication and mobile communication, CDMA has not given full play to its advantages, and optical fiber communication has abundant bandwidth, which can make up for this defect well.CDMA has become a high-profile technology in recent years.OCDMA technology is similar to code division multiplexing technology in principle.The OCDMA communication system assigns a unique optical orthogonal code to each user as the address code of the user.At the sending end, optical orthogonal encoding is performed on the address code of the transmitted data, and then channel multiplexing is realized; at the receiving end, the same address code as the sending end is used for optical orthogonal decoding.