What is Downlink?

In RF wireless communications like cellular or satellite networks, the term downlink indicates transmissions from network infrastructure to user devices.

Wireless networks are composed of 2 main parts - the network side and the mobile/fixed subscriber side (users). The users access the network through various devices like smartphones, mobile phones, tablets etc. Downlink is used to indicate the transmission route from the network side to mobile or fixed terminals (subscribers). The frequency used for all downlink transmissions is known as downlink frequency.

Most technologies have different Uplink and Downlink frequency bands. For example, GSM cellular networks use the 935 MHz to 960 MHz band for downlink transmission. In satellite C-Band communications 3700-4200 MHz is the downlink band. Satellite networks also use 11.7-12.2 GHz (Ku-Band) and 17.7-21.2 GHz (Ka-band) for downlink. An RF device called a downconverter is used to convert an RF frequency to a baseband frequency for receptions on the downlink side. Some companies sell uplink and downlink services to television stations, corporations and other telecommunication carriers. A company may specialize in providing downlink services, uplink services or both.

In wireless networks, ‘downlink' is also used to indicate other terms related to downlink transmissions like downlink channels, downlink frame structures, downlink packets etc.

The transmission of signals from the user's device to the network is called uplink. Click here to learn more about uplink.