A high level overview of smart antennas
Smart antenna concepts include many methods to improve communications network performance. In this overview we will summarise the principles of diversity, beamforming, MIMO methods and also consider Multiple User Detection (MUD) methods of interference cancellation. Whilst Multiple User Detection does not require multiple antenna elements, it is a method that can improve system performance, and canbenefit when used with multiple antennas, and is therefore relevant to the consideration of smart antenna methods, in general.
MIMO (Multiple Input Multiple Output) communication methods are based on using a number of transmit antennas, N, each of whose signals are received by a number of receivers M. Hence there areN.M paths between the transmitter and receiver.
What is MIMO Wireless Technology
MIMO: Multiple Input Multiple Output technology uses multiple antennas to make use of reflected signals to provide gains in channel robustness and throughput.
MIMO, is a technology that was introduced into many wireless communications systems including 4G LTE to improve the signal performance.
LTE MIMO modes
This is the form of wireless transmission used on most basic wireless links.
Transmit diversity:This form of LTE MIMO scheme utilises the transmission of the same information stream from multiple antennas.
Open loop spatial multiplexing:
This form of MIMO used within the LTE system involves sending two information streams which can be transmitted over two or more antennas.
Close loop spatial multiplexing:This is another form of LTE MIMO, but where a single code word is transmitted over a single spatial layer.
Closed loop with pre-coding:
This is another form of LTE MIMO, but where a single code word is transmitted over a single spatial layer.
Multi-User MIMO, MU-MIMO:
This form of LTE MIMO enables the system to target different spatial streams to different users.
Beam-forming & MIMO:
Beam-forming & MIMO:
This is the most complex of the MIMO modes and it is likely to use linear arrays that will enable the antenna to focus on a particular area.