1 research outputs found
Beamforming and precoding techniques
Beamforming and precoding/combining are techniques aimed at processing
multiantenna signals at the transmitter and/or at the receiver of a wireless
communication system. While they have been routinely used to improve
performance in current and previous generations of mobile communications
systems, they are expected to play a more fundamental role in 5th Generation
(5G) New Radio (NR) cellular systems, whose functionalities have been defined
in the first phase of 3GPP 5G standardization process. Besides operating in
traditional cellular sub-6 GHz frequency band, 5G NR has been natively designed
also to work in the higher millimeter-wave (MMW) band. At lower frequencies,
multiantenna techniques for 5G NR are mainly refinements of those originally
designed for 4G Long Term Evolution (LTE). On the contrary, to cope with the
peculiarities of MMW scenarios, such as the larger number of antenna elements,
the more directional transmission, and the higher path loss values, new
dynamic, user-specific, and computationally-efficient multiantenna solutions
and procedures have been incorporated in 5G NR specifications. In particular,
since multiantenna techniques for 5G NR generally need detailed channel state
information (CSI), a complete redesign of the set of reference signals and
procedures used for CSI acquisition and reporting was carried out. 5G NR is
continuously evolving and new features will be added, while the existing ones
will be enhanced in the second phase of 5G standardization, with emphasis on
reduction of CSI overhead, robustness against spatial correlation among
channels, unconventional transmission methods, and software-based
reconfigurable antennas