MIMO Wireless LAN PHY Layer Operation and Measurement
Application Notes
This Keysight Technologies, Inc. application note is written for people who need an understanding of MIMO radio operation as it applies to WLAN, and the test configurations for multi-channel radios. Increasing use of wireless systems and new applications like digital video streaming mean a continued desire for higher throughput or better coverage from radio systems. To some extent, the use of more complex modulation formats such as Orthogonal Frequency Division Multiplexing (OFDM) and 64 QAM has satisfied this need, but further advances are being made. Changing the use of the spectrum available is being pursued in several ways. Ultra-Wideband (UWB) is one approach for increasing throughput; another is called Multi-Input Multi-Output radio (MIMO)1. MIMO radios get more from the RF bandwidth they occupy than their single channel equivalents, by exploiting differences in the paths between each of the transmitter and receiver inputs. If a conventional single channel radio system creates one “pipe” between the transmitter and receiver, the object of a MIMO radio system is to create multiple pipes. It does this by creating a mathematical model of the paths from transmitters to receivers, and solving the resulting equations.