MIMO and Spectrum Sharing

MIMO (multiple-input, multiple-output) communication architectures will be a key to unlocking new high-frequency spectrum needed to satisfy skyrocketing wireless-data demand and is a central facet of next-generation 5G wireless.

NIST CTL’s Shared Spectrum Metrology Group studies the impact of MIMO, massive MIMO and multi-user MIMO on spectrum sharing and coexistence.

In our research of MIMO’s impact on coexistence metrology we are investigating:
   • How the density of antenna elements affects the grating lobes, interference, channel state information, and correlation between channels
   • Ways in which multiple beams and users require more complex characterization of the interference source than a classic omnidirectional pattern.
   • What antenna considerations beyond basic gain patterns are needed to evaluate a MIMO system’s coexistence performance.

MIMO coexistence testing is complex. We must take into account key architectures in recent and emerging communication systems, such as IEEE 802.11n and 802.11ac, which embrace complex RF propagation environments, multiplex multiple communication channels in space, and signal processing techniques like “nullforming” interference suppression. Advances in testing these systems would give industry valuable tools to improve the robustness of their own systems and better coexist with others.