duplex spacing
Duplex spacing refers to the safety frequency band between the uplink and downlink channels in duplex operation via radio links in mobile communications and satellite transmission.
In the GSM standard, for example, a duplex spacing of 190 MHz between the uplink and downlink channels is specified in the 1.8 GHz frequency band. If a network operator uses the frequency range from 1.920 GHz to 1.925 GHz for the uplink, it must use the frequency range from 2.110 GHz to 2.115 GHz for the downlink.