MIMO Multiple-in, Multiple-out

Understanding the Basics of MIMO Communication Technology

4 x 4  MIMO System

Radio systems utilizing MIMO (multiple-in, multiple-out) technology have become increasingly common over the past several decades, with notable examples being Wi-Fi networks and cellular 3G / 4G LTE & massive MIMO system that make up a large part of our modern communication infrastructure.

More recently, MIMO has been finding its way into rapidly growing markets such as professional broadcast video, law enforcement, and government sectors thanks to newer generations of smaller, better performing radio solutions and antenna designs that support MIMO technology. With the bandwidth requirements that today’s video, audio, and data systems demand, MIMO is often an ideal solution for communication especially urban environments where clear line-of-site is harder to achieve and the abundance RF / microwave systems that can pose interference issues.

There are many types of MIMO systems currently in use, with different MIMO radio manufacturers offering their own versions of the technology with unique features and advantages. The new generation of small, high-performance tactical MIMO radios allows for the benefits of MIMO to be utilize by smaller groups as well as large organizations. Ad-hoc and mesh networking capabilities of many radio systems allows for dynamic deployment and quick response to changing situations without network outages.

Adam Krumbein Marketing Director, Southwest Antennas has prepared a general education White Paper Understanding the Basics of MIMO Communications Technology geared Business Professionals and Technology Staff and available for download.

This white paper discusses topics related to the basics of understanding MIMO communication that can be understood by readers of all levels of technical levels, particularly those that are new to the RF market or have no previous working experience with MIMO technology.

MIMO Overview

An acronym for Multiple-In, Multiple-Out, MIMO communication sends the same data as several signals simultaneously through multiple antennas, while still utilizing a single radio channel. This is a form of antenna diversity, which uses multiple antennas to improve signal quality and strength of an RF link. The data is split into multiple data streams at the transmission point and recombined on the receive side by another MIMO radio configured with the same number of antennas. The receiver is designed to take into account the slight time difference between receptions of each signal, any additional noise or interference, and even lost signals.

By transmitting the same data on multiple streams, the MIMO radios introduce redundancy into data transmission that classic single antenna setups (SISO: Single In, Single Out) can’t provide. This gives MIMO systems several advantages over typical SISO configurations:

  1. MIMO radios can utilize the bounced and reflected RF transmissions (known as multipath propagation) to actually improve signal strength even without clear line-of-site, since MIMO radios receive and combine multiple streams of the same data that are received at slightly different time intervals. This is particularly useful in urban environments, where signal degradation between single antennas without clear line-of-site is a major issue. Urban environments provide plenty of reflection paths for MIMO signals to take between the transmit and receive radios.
  2. Overall throughput can be improved, allowing for greater quality and quantity of video or other data to be sent over the network.
  3. By utilizing multiple data streams, issues such as fading caused lost or dropped data packets can be reduced, resulting in better video or audio quality.