Stanford University start-up Kumu came to the world’s attention earlier this year with a breakthrough that allows incoming and outgoing signals to use the same frequency without interference, effectively doing away with the FDD/TDD difference. Now the organization has found a way to incorporate its technology relatively easily in existing base stations, potentially paving the way for near term market adoption, rather than having to wait for the next wave of wireless systems.
Kumu’s Steven Hong told the ThinkSmallCell newsletter that “there is no DD anymore – not FDD or TDD”, and moreover, that it would be fairly easy to enable standard base stations to apparently defy the laws of physics in this way. The group can connect a smart echo-canceller in place of the usual RF rx/tx combiner/splitter, he explained.
Radios generally use separate frequencies to send and receive, or switch between send and receive modes on the same frequency, otherwise the outgoing signal will drown out the inbound one. But the Kumu radio generates an additional signal that cancels out the interference. This is a different approach to established interference cancellation techniques, and could be applied to cellular networks or to WiFi.
That could lead to significantly better spectrum usage and data rates, since all the spectrum could be used for both uploading and downloading at the same time. For instance, spare macrocell capacity created via this approach could be harnessed for backhauling nearby small cells, dividing the full 100Mbps of capacity in the macro sector between several metrocells, which would not need their own backhaul, and could also act as relays. In this scenario, the small cell would need to implement the special receiver but no special handsets or macrocells would be required.
Another potential, and topical, application is to combine WiFi and LTE-U (LTE using 5GHz carriers for supplemental capacity) in one box while avoiding the usual interference issues.
Kumu says it has completed proof of concept trials successfully with four tier one operators and will run field trials, using equipment from major vendors, in 2015, with commercial deployment the following year.