Kumu claims its self-interference solution doubles capacity

Kumu Networks, a startup formed by Stanford University researchers, asserts it has found the key to "wireless full duplex" and can enable a radio to simultaneously transmit and receive overlapping signals within a single frequency channel.

The Santa Clara, Calif., company claims to have perfected self-interference cancellation, so a receiver will hear zero noise from its transmitter and, thus, receive external signals without impediment. "Imagine FDD performance within a single unpaired TDD channel," said the company on its website, adding that its technology can effectively double the spectral efficiency of every radio in the world, including cellular and Wi-Fi.

Kumu is funded with $10 million from investors that include angels as well as venture capital firms New Enterprise Associates and Khosla Ventures. The startup told the Wall Street Journal that it is preparing to trial prototypes with undisclosed partners within six months and is on the hunt for more funding before it delivers commercial product to carriers, possibly sometime next year.

Mobile operators in developed markets have been rushing out LTE technology and are already moving onto LTE Advanced in order to wring more capacity and better performance out of their networks. Just this week, Sprint (NYSE:S) CTO Stephen Bye described how that operator will use bandwidth aggregation (which could be carrier aggregation via LTE Advanced standards), higher-order MIMO antenna technology and also coordinated multi-point (CoMP) transmission, which improves spectral efficiency and cell-edge user performance in LTE Advanced.

Kumu CEO and Co-Founder Sachin Katti, who is also assistant professor of electrical engineering and computer science at Stanford, told the Journal that Kumu's technology is the one major tool left for wireless operators to improve spectral efficiency.

However, Joe Madden, principal analyst at Mobile Experts, contends Kumu does not appear to have anything more to offer than a niche technology. "From what I've seen, I'm not convinced," he said.

A white paper describing the company's technology notes that "full duplex radio design is a problem that spans three different research areas: RF circuit & system design, digital signal processing and networking." Because the problem cannot be solved in any one domain alone, "the solution in our opinion requires understanding trade-offs across all these domains and architecting it appropriately," the paper added.

The company claims there are some initial applications that can employ its approach without modifying existing technical standards. One area is backhaul, both for macro cells and small cells. In the case of the latter, "the access and backhaul radios can operate simultaneously on the same frequency, allowing the small cell to backhaul itself while maintaining end-end throughput," Kumu said.

According to Kumu, its self-interference cancellation can also improve  Wi-Fi quality of service at crowded venues such as stadiums. Further, the technology can act as a "software configurable filter" to facilitate global LTE roaming and sharing of TV white space. Yet another application involves jamming enemy radios, and only enemy radios, which are used to activate remote improvised explosive devices (IEDs).

According to Katti, Kumu has been speaking with senior executives at cellular carriers, equipment and semiconductor manufacturers but needs to show them that the technology can scale.

For more:
- see the Kumu website and this white paper (PDF)
- see this Wall Street Journal article (sub. req.)

Related articles:
Sprint to use bandwidth aggregation, MIMO and CoMP to handle LTE traffic
SK Telecom: Take a closer look at its LTE Advanced rollout
LTE Advanced is the next competitive battleground for operators
Researchers: Full-duplex radios could double spectral efficiency

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