TDD/FDD Access
LTE standards support the use of both TDD (Time Domain Duplex) and FDD (Frequency Domain Duplex) from the same set of standards, and with the same air interface characteristics.
Multiple Input Multiple Out (MIMO)
MIMO is an antenna technology that, together with signal processing, can either increase capacity (spatial multiplexing) or signal-to-noise ratio (transmit diversity) in a radio link.
In LTE using 2x2 MIMO with spatial multiplexing, the user data is separated into two data sets each fed to two transmit antennas and received by two receive antennas. Because of multi-path, each data set travels a distinct RF path with different propagation characteristics. The algorithm used to split and recombine the data allows the system to make use of the independence of these two paths in order to improve throughput. The two data streams occupy the same RF channel at the same time. This doubles the data rate possible on the air interface link.
When using MIMO with transmit diversity, the same user data is transmitted from both antennas, and at each receiver, replicas of the signal are processed. This duplication enhances signal-to-noise ratio and improves signal robustness.
Related manufacturers: VIAVI Solutions (d.Aeroflex), Anritsu Corporation
