Uplink and Downlink Transmission in Satellite Communication

Uplink and Downlink Transmission (http://techbooksforfree.com)  

Two ways of transmissions in satellite communications are Uplink and Downlink. We call a downlink if communication from a satellite down to ground receivers or stations. Contrary, we call an uplink if communication is going from ground receivers up to a satellite. 

Commercially, many companies provided both downlink and uplink services. But, several companies either sell uplink or downlink only. Corporations such as telephone companies, wireless networks, television stations and other relate communication corporations buy uplink and downlink services to serve their customers.  

Rouse (2007) gave three examples of commonly frequency bands in satellite links, they are Ku, Ka and C bands. Please see the Table below:

Frequency Band	Downlink	Uplink
C	3,700-4,200 MHz	5,925-6,425 MHz
Ku	11.7-12.2 GHz	14.0-14.5 GHz
Ka	17.7-21.2 GHz	27.5-31.0 GHz

From the Table, we could examine that uplink frequency is higher than downlink one. Several reasons why this happen are following:

1.Stations on the earth have greater power, thus able to send higher frequencies to satellites (uplink)

2.Higher frequency signals could eliminate ionized particles at Ionosphere, thus higher frequencies of uplinks more effective than lower ones to reach satellite from ground stations.

3.Since satellites have lower power, because using of solar panels, thus lower frequencies is effective from Satellites to ground stations (downlink). 

In conclusion, each of Uplinks and Downlinks has own effectives in communications. Downlink with lower frequency is more precious than using higher frequency, on the contrary, Uplink is advantage to use higher frequencies. 

Reference

Rouse, M. (2007, May).” downlink and uplink.” Retrieved from https://searchmobilecomputing.techtarget.com/definition/downlink-and-uplink