Spectrum Multiplier software from Cohere Technologies uses Delay-Doppler effects to predict how a wireless channel will change in real time, letting base stations and the telco cloud control MU-MIMO beams.
Wireless connectivity takes an enormous amount of computing power. Computing occurs from the radio’s physical layer to coding through to the fronthaul, mid-haul, and backhaul and to the network core. Anywhere that computing resources can be reduced is welcome because that reduces latency, energy consumption, and cost. Cohere Technologies has developed software that reduces the need to calculate a channel’s characteristics every millisecond.
Cohere’s software uses the effects of Delay Doppler to predict a mobile user’s future location, which helps a base station’s antenna signal beams keep up with a user. “Mobile devices receive signals directly from a base station and from reflected signals,” said Dolan. “The problem is that a base station must update itself every millisecond to keep up not only as users move because of a changing wireless channel.” Channel characteristics can change even when a user is stationary, say when a bus passes nearby to the user.
“Updating a user’s position every millisecond using time and frequency takes lots of computing power, which consumes a lot of energy.” Using Delay Doppler, the software, running in the cloud, can predict changes in a channel, from which the base station can steer the beam. If this case, “future” means milliseconds. “Once you solve the position problem with Delay Doppler,” said Dolan, “the future of the channel becomes predictable.”
Dolan also noted that the technique is independent of carrier frequency. That is, you can use the uplink information to predict where the downlink beam should go next because Delay Doppler relies on phase shift to map a channel’s characteristics as opposed to measuring time and frequency, which base stations do now.