Inside the huge data centers operated by Internet companies like Google, Amazon, and Facebook, information is processed at blistering speed, but it still has to be moved between different machines through relatively slow wiring.
In theory, this bottleneck could be avoided by adding wired links between racks, but that would be very expensive and, short of a complete architectural redesign, not particularly practical. Transmitting data wirelessly would be simpler, but achieving the required speed would normally require a line-of-sight connection, which is impossible in a packed data center.
Flat metal plates placed on the ceiling can provide nearly perfect reflection.
Zheng created a simulation of a 160-rack data center to see how the system might affect performance. “Our simulation shows that wireless can add 0.5 terabytes per second,” she says.
Zheng and colleagues used 60-gigahertz Wi-Fi, which has a bandwidth in the gigabits-per-second range and was developed for high-definition wireless communications (the first commercial products that use the standard will hit the market next year). However, it has its limitations, says Zheng. To maximize the bandwidth and reduce interference between signals, it needs to be focused into narrow beams that require a direct line of sight between endpoints. “Any obstacle larger than 2.5 millimeters can block the signal,” she says.
One way to prevent the antennas from blocking each other would be to allow them to communicate only with their immediate neighbors, creating a type of mesh network. But that would further complicate efforts to route the data to the appropriate destinations, says Zheng. Bouncing the beams off the ceiling directly to their targets not only ensures direct point-to-point communication between antennas but also reduces the chances that any two beams will cross and cause interference.