A Rice University wireless antenna rig, known as Argos, represents the largest such array yet built and will serve as a test bed for a concept known as “Massive MIMO.”
MIMO, or “multiple-input, multiple-output,” is a wireless networking technique aimed at transferring data more efficiently by having several antennas work together to exploit a natural phenomenon that occurs when signals are reflected en route to a receiver. The phenomenon, known as multipath, can cause interference, but MIMO alters the timing of data transmissions in order to increase throughput using the reflected signals.
MIMO is already used for 4G LTE and in the latest version of Wi-Fi, called 802.11ac; but it typically involves only a handful of transmitting and receiving antennas. Massive MIMO extends this approach by using scores or even hundreds of antennas. It increases capacity further by effectively focusing signals on individual users, allowing numerous signals to be sent over the same frequency at once. Indeed, an earlier version of Argos, with 64 antennas, demonstrated that network capacity could be boosted by more than a factor of 10.
An alternative, or perhaps complementary, approach to an eventual 5G standard would use extremely high frequencies, around 28 gigahertz. Wavelengths at this frequency are around two orders of magnitude smaller than the frequencies that carry cellular communications today, allowing more antennas to be packed into the same space, such as within a smartphone. But since 28 gigahertz signals are easily blocked by buildings, and even foliage and rain, they’ve long been seen as unusable except in special line-of-sight applications.
But Samsung and New York University have collaborated to solve this, also by using multi-antenna arrays. They send the same signal over 64 antennas, dividing it up to speed up throughput, and dynamically changing which antennas are used and the direction the signal is sent to get around environmental blockages