Wednesday, August 3, 2011

Wireless inventors hype DIDO. No... not the singer!

Inventors from Rearden Labs claim to have invented a "new kind of wireless network"
that deliberately creates interference in order to increase capacity and speed of wireless networks.
In separate stories today on the front page of the San Jose Mercury News, and in the MIT Technology Review, Steve Perlman, CEO of on-demand gaming site OnLive, claims that he and a team of engineers at his Rearden Labs incubator have developed a "Breakthrough" that "Unlocks Faster Mobile Data" in wireless networks. Perlman was previously involved with the creation of the QuickTime media player at Apple, and was founder of WebTV.

According to the Mercury News, Perlman claims that  his technology, which he calls DIDO (Distributed-Input-Distributed Output), can increase wireless data throughput  by embracing interference. 
(DIDO) uses multiple transmitters to create unique interference patterns at particular points in space that essentially become unique channels to which one or more devices can connect.
At first glance, there would seem to be a number of obvious DIDO RAN (radio access network) architectural similarities to current 4G techniques: MIMO (multiple input multiple output), pico/femto cells, and cloud-based RAN to name a few. A key to the DIDO system is to use the cloud, or a remote signal processing data center, to tune the signals that each radio head transmits based on the location and number of other DIDO transmitters in a particular area. By doing so, according to the Technology Review article, Perlman claims to have come up with a "new kind of wireless network" with thousands of times the capacity of a conventional network. By combining signals from multiple transmitters, the DIDO technique is claimed to be capable of creating "a bubble of crystal-clear reception around every user". The Technology Review did point out one possible downside - DIDO doesn't work for upload.

How creating separate, apparently localized, channels in this manner could increase the capacity of available spectrum is (no pun intended) unclear. Support for non-stationary receivers would also appear to be a huge issue. The technique also requires dedicated private spectrum, so it can't be used to fix congestion in WiFi hotspots. It would appear that the invention actually needs to avoid interference that is not of its own making, not exactly a viable real-world proposition.

While the Mercury News claimed that Perlman has released few of the technical details, so that it is difficult for experts to assess the credibility of the invention and his claims, there is actually a wealth of information that is freely available. Perlman and his colleagues have been granted a total of 4 U.S. patents:

7636381 System and method for distributed input-distributed output wireless communications  
A system for dynamically adapting the communication characteristics of a multiple antenna system (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as a...
7633994 System and method for distributed input-distributed output wireless communications  
A system for compensating for in-phase and quadrature (I/Q) imbalances for multiple antenna systems (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as...
7711030 System and method for spatial-multiplexed tropospheric scatter communications  
A method is described comprising: transmitting a training signal from each antenna of a base station to each of a plurality of client devices utilizing tropospheric scatter, each of the client...
7599420 System and method for distributed input distributed output wireless communications  
A system and method are described for compensating for frequency and phase offsets in a multiple antenna system (MAS) with multi-user (MU) transmissions (“MU-MAS”). For example, a method...

Though the association with a gaming site, where Perlman is CEO, is puzzling for an invention requiring expertise in radio engineering and DSP (digital signal processing), the list of inventors in the DIDO patents includes two wireless engineers with backgrounds that include Freescale Semiconductor and Samsung, according to LinkedIn.The other two co-inventors are OnLive employees.

A search at found that the Rearden team also has 13 patent applications pending. Experts in wireless system design are invited to review the technical details behind DIDO, and share your opinions and comments with the EE Daily News.

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