PDF of this tutorialNetwork Node
LMDS network node RF equipment includes transmitters and receivers as well as transceivers and the antennas they feed. If there is one carrier per transmitter, the system is said to be channelized. If there are multiple carriers per transmitter, the system is said to be broadband.
Transmitters
Individually modulated signals are combined and applied to the broadband transmitter. Within the transmitter, the very-high-frequency (VHF) signals are converted up to the desired carrier frequency, amplified, and applied to the antenna for transmission. Separate transmitters, receivers, and antennas can be used in each direction to minimize the near-end crosstalk effects between transmit and receive signals.
Receivers
A separate broadband receiver receives the entire band at carrier frequency and converts the signals to the VHF band. The VHF signals are then applied to coaxial or fiber cable for distribution to the NNE.
Transceivers
Combined transmitter and receiver functions can be provided in a single broadband transceiver.
Antenna Systems
Antennas are chosen based on the desired coverage of potential subscribers, taking into consideration the terrain, interfering objects, antenna azimuth pattern, antenna elevation pattern, and antenna gain.
Customer-Premises Site
Transceiver
For two-way data network applications, a transceiver is used to provide a return path for LMDS services. The antenna may be an integral part of the transceiver. The transceiver may be broadband or channelized.
Customer Antenna Systems
Typical technology choices available include microstrip design, parabolic and grid-parabolic reflectors, and horn designs. The selection is an engineering decision based on the customer's location. As well, vendors will have various levels of integration with specific antenna technologies.
