MIMO is an acronym and it stands for multiple inputs, multiple outputs. A qualified radio communications technology, it is often integrated and a fundamental component in many new technologies that we have today. That is how indispensable mimo antennas are.
Long term evolution, LTE, WiFi, and a handful of other wireless, radio, and RF technologies are utilizing MIMO wireless technology in providing enhanced link capacity. At the same time also, it is offering us spectral efficiency coupled with upgraded link reliability which is made possible by interference paths.
Even now we can see with our own eyes that our market is already flooded with a great deal of MIMO wireless-based routers. While this radio frequency technology is gaining more and more acceptance and thus its use/application coverage is increasing, too, it can be anticipated as early as now that we are bound to see more MIMO routers and other comparable wireless MIMO devices and equipment in the coming days.
Development and History of MIMO Antenna Technology
Over the years, MIMO technology was gradually developed. Apart from formulating first its fundamental concepts, new complementing technologies had to be developed as well alongside it. Otherwise, leaving either of the two behind will render the MIMO technology not fully working today.
In its early days, new processing levels were necessary for MIMO technology because they allowed spatial multiplexing features to make use of some of the advantages being offered by spatial diversity.
Spatial diversity was often restricted to systems that had to switch between 2 antennas. Sometimes also, it is necessary to make use of merged signals to come up with the best signal possible. That was a typical scenario back then and it was so until the 1990s.
Besides, during this time also, a glut of beam switches were implemented. But with regard to the involved processing levels, together with degrees of processing available, the systems can be best described as generally limited.
But with the gradual availability of additional processing power, utilizing both the full spatial multiplexing and spatial biodiversity is needed. The preliminary work that was done before on MIMO systems most of the time centered upon the fundamentals of spatial diversity. The MIMO system here was used on implementing a limit on the amount of possible deterioration that multipath propagation is known to bring about.
During that time also, the system already began to take advantage of the multipath propagation. Consequently, this has made the additional signal paths to become additional channels whose primary purpose is to carry additional data.
Two of the researchers then, by the name of Arogyaswami Paulraj and Thomas Kailath, originally proposed in 1993 the use of spatial multiplexing. This helped in paving the way for its US patent to be granted to it which happened the following year.
One of the advantages of MIMO antenna spatial multiplexing is that it allows for an increase of spectral efficiency sans lowering the link robustness as much as going to order constellations.
For better understanding, here is an example. A 16-QAM with a decently strong FEC coding rate will let you achieve a close to 4 bits/sec/Hz by utilizing 2 streams. In the absence of MIMO here, the system will be compelled to make use of 64-QAM with a weaker FEC coding rate.
By this measure, it would be able to obtain comparable throughput on a similar channel. And there are two possible outcomes for this, it would either lead to the need for a higher transmit power or would just limit its range.