3G MIMO

3G MIMO describes MIMO techniques which have been considered as 3G standard techniques.
MIMO, as the state of the art of intelligent antenna, 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, self-tracking directional antenna, cooperative virtual antenna and so on.

Technology

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.

Summary of 3G MIMO

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.

Generation	3G	3G evolution	Beyond 3G	Future
Deployment	2003/4	2005~6/2007~8/2009~10	2012~2015	2015~2020
Standard	WCDMA	HSPA/HSPA+/LTE	IMT-Advanced	Beyond IMT-Adv
Total rate	384kbit/s	14/42/65~250Mbit/s	1Gbit/s	>10Gbit/s
Bandwidth	5 MHz	5 MHz/20 MHz	20~100 MHz	>100 MHz
Requirement Paradigm	High reliability	High rate	Lower interference	High intelligence
Method	Spatial diversity	Spatial multiplexing	Spatial cancellation	Ambient intelligence
Spatial coding	Spatial diversity coding	Spatial multiplexing coding	Spatial cancellation coding	Ambient intelligence coding
Spatial beamforming	Single-stream beamforming	Multi-stream beamforming	Interference nulling beamforming	Ambient intelligence beamforming
Examples	SC: Alamouti coding, SB: TxAA	SC: BLAST coding, SB: SVD	SC: DPC, SB: MU-BF	Such as cooperative MIMO

IA in ad hoc networking

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. 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 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.

Principal Issues of Research

The following items list the issues of the multiple antenna research aims to improve the performance of radio communications.

Principal Definitions

Definitions

Here are the definition of principal keywords to clarify the objective and the operations of intelligent antenna.

Terminology	Definition
Intelligent antenna	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.
Smart antenna	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.
MIMO	Wide sense and well-known: MIMO is the state of the art of IA and SA. Narrow sense: Antenna systems that employ multiple antennas at both the transmitter and the receiver.