PORTLAND, Ore. As the wireless era cuts the last remaining ties to land lines, standards have begun to overtake proprietary solutions. Unfortunately, high-definition audio still relies on proprietary algorithms to manage communications in the crowded, unlicensed 2.4-GHz band where Wi-Fi and Bluetooth standards must co-exist with cordless phones and microwave ovens.
Now ultrawideband (UWB) is aiming to bring order to the chaos, by enabling HD audio to move into the unlicensed 3.1- to 10.6-GHz band designated for personal area networks. What is claimed as the world's first UWB wireless audio solution will be demonstrated at the Consumer Electronics Show next week (Jan. 7-10) by Radiient Technologies Inc. (Santa Clara, Calif.).
"We have developed [a] wireless surround sound on top of ultrawideband with absolutely no audio dropout," claimed Jano Banks, president of Radiient Technologies.
Radiient's Roomcaster prototype makes use of an emerging crop of UWB chip sets to broadcast very low power, UWB pulse codes that are virtually immune to multipath interference over short ranges. The prototype, for which Radiient has yet to select a vendor for its UWB radio chip, is designed to enable audio networks in a single room since UWB does not penetrate walls.
UWB supports data rates as high as 675 Mbits/sec, compared to 54 MBbit/sec for Wi-Fi. With the wider available bandwidth, all five channels in a surround sound system could be transmitted wirelessly, and at very low power levels.
"UWB gives us virtually unlimited channels to chose from. We are using channels hundreds of megahertz wide in the 3- to 10-GHz band, compared to 20-MHz-wide channels in the 2.4-GHz band," said Banks. "The beauty of UWB for use with audio is that it has plenty of bandwidth for all the surround sound speakers, plus its very fast with only 16 milliseconds of latency, so there are no lip-sync issues when its used together with high-definition video."
The human brain can only detect lip-sync problems when latency exceeds 20 milliseconds, but UWB enables such speedy communications that corrupted data packets have time to not only be retransmitted, but to be re-routed as necessary without increasing latency. The prototype maintains two-way communications channels to each remote speaker from its host unit connected to the audio source, then implements a mesh network that sends audio data streams to every speaker.
"We have built a mesh network on top of UWB to make our communication robust," said Banks. "We both send audio to speakers and receive signals back from them."
Since every speaker is receiving all data streams, and the mesh network enables speakers to use their transceivers to communicate with each other, errant data packets can be re-routed from one speaker to the next to avoid interference.
"With our peer-to-peer architecture, the more channels you add, the better your performance, because there are more routes available for communications," said Banks.
Despite occasional retransmissions of data packets, the high-speed of UWB communications enables the prototype to synchronize among the signals emerging from speakers at about 100 microseconds. Even when corrupted data packets have to be retransmitted, Radiient claims 1-millisecond synchronization among channels.
The Roomcaster prototype being demonstrated at CES is based on and ARM-9 processor core and uses a UWB radio chip made by an unspecified semiconductor house. Radiient is currently experimenting with different manufacturers' chip sets, and has yet to decide on a vendor. Final product roll out is scheduled for later in 2008.
Radiient is also developing UWB systems that simultaneously communicate with wireless headphones and microphones with speakers. The company said Skype and other Internet telephone services could be integrated with its high-fidelity music distribution system.