A
repeater allows terminals of a first
communications system, employing a first air protocol or
radio interface, to communicate with terminals of a second
communications system, employing a second air protocol or
radio interface different from the first. Where the first and second air protocols differ only in
operating frequency, but are otherwise compatible, the
repeater may linearly translate signals from the first
operating frequency to the second
operating frequency, and vice versa, without demodulating and remodulating the signals. Where the air protocols differ in other ways, the
repeater receives and demodulates signals from the first
system, converts the signals to a common format, and remodulates and retransmits the signals according to the second air protocol (and vice versa), in the same frequency bands or in different frequency bands. The repeater translates control and signalling information transmitted in compliance with one air protocol to a format which complies with the other air protocol and has the same or equivalent effect. For each of the two
communications system, the repeater emulates the functions of a terminal in that communications
system, so that corresponding terminals in that
system may communicate transparently with the repeater. The repeater provides a connection between the two emulated terminals, thereby allowing a terminal of the first system to use the repeater to communicate with an otherwise incompatible terminal of the second system.