3G MIMO describes MIMO techniques which have been considered as 3G standard techniques.
MIMO, as the state of the art of intelligent antenna (IA), improves the performance of radio systems by embedding electronics intelligence into the spatial processing unit. Spatial processing includes spatial precoding at the transmitter and spatial postcoding at the receiver, which are dual each other from information signal processing theoretic point of view. Intelligent antenna is technology which represents smart antenna, multiple antenna (MIMO), self-tracking directional antenna, cooperative virtual antenna and so on.
Spatial precoding of intelligent antenna includes spatial beamforming and spatial coding. In wireless communications, spatial precoding has been developing for high reliability, high rate and lower interference as shown in the following table.
The table summarizes the history of 3G MIMO techniques candidated for 3G standards. Although the table additionally contains the future part but the contents are not clearly filled out since the future is not precisely predictable.
IA technology enables client terminals, which have either multiple antennas or a self-tracking directional antenna, to communicate to each other with as high as possible signal-to-interference-and-noise ratio (SINR). Assume that there is a source terminal, a destination terminal, and some candidate interference terminals. Compared to conventional approaches, an advanced IA based terminal will perform spatial precoding (spatial beamforming and/or spatial coding) not only to enhance the signal power at the destination terminal but also to diminish the interfering power at interference terminals. As a human does, the advanced IA terminal is given to know that occurring high interference to other terminals will eventually degrade the performance of the associated wireless network.
Antenna technology that uses some sort of electronic intelligence to enhance wireless system performance. Electronic intelligence is implemented by spatial pre/post-coding techniques such as spatial information coding and spatial signal beamforming. Smart antenna has been more widely used to represent the similar meaning.
In the narrow sense, antenna technology that employs array antennas with beamforming techniques to enhance wireless system performance. In the wide sense, equivalent terminology to intelligent antenna.
Multiple antenna systems are the key to the high-capacity wireless universe. Indeed, they allow increasing the rate, improving the robustness, or accommodating more users in the cell.
A smart antenna system combines multiple antenna elements with a signal-processing capability to optimize its radiation and/or reception pattern automatically in response to the signal environment.
Spatial division multiple access (SDMA) — Among the most sophisticated utilizations of smart antenna technology is SDMA, which employs advanced processing techniques to, in effect, locate and track fixed or mobile terminals, adaptively steering transmission signals toward users and away from interferers.
A smart antenna is a digital wireless communications antenna system that takes advantage of diversity effect at the source (transmitter), the destination (receiver), or both.
MIMO is an antenna technology for wireless communications in which multiple antennas are used at both the source (transmitter) and the destination (receiver).
Smart Antennas Research Group, Stanford Univ. — [7]
Our research goal is to advance the state-of-the-art in the applications of multiple antennas and space-time signal processing in mobile wireless networks, and to improve network performance and economics.
Smart antennas provide greater capacity and performance benefits than standard antennas because they can be used to customize and fine-tune antenna coverage patterns that match the traffic conditions in a wireless network or that are better suited for complex radio frequency (RF) environments.
MIMO employs multiple, spatially separated antennas (at both TX and RX) to take advantage of these "virtual wires" and transfer more data.
Intelligent antennas are antenna systems that use some sort of computational or electronic resource to enhance system performance.
According to the amounts of intelligence employed, antenna diversity represents the simplest form in the progressive complexity chain, followed by basic beamforming, which is the process of narrowing radiated energy, which is then followed by the more complex space-time processing and finally by MIMO.
