Bell Labs demoes 19.2Mbps 3G chips
Boffins at Lucent Technologies' Bell Labs have successfully tested two prototype ultra-fast mobile chips at speeds of up to 19.2Mbps.
By comparison, chips destined for the fastest 3G networks today offer maximum speeds of roughly 2.5 Mbps.
The two prototype Bell Labs chips, which conform to industry standards for size and power consumption, are based on technology called Bell Labs Layered Space-Time (BLAST).
BLAST uses multiple antennas at the terminal and base station to send and receive wireless signals at ultra-high speeds. It relies on innovative signal processing techniques to send and successfully decode several transmissions within the same frequency band. When utilised in base station equipment and mobile devices, this technology permits far higher transmission speeds to be achieved.
Implementing multiple input/multiple output (MIMO) wireless network technology on silicon to take advantage of the BLAST has proved a challenge for the industry. Now Lucent believes it's cracked the problem, opening up the path to commercial deployment of the technology over an (as yet) unspecified timeframe.
"We believe ours are the world's first chips that can be used in handsets with four antennas, and therefore the first capable of such high transmission speeds," said Ran Yan, vice president, Wireless Research at Bell Labs.
"Not only have we proven the commercial feasibility of BLAST, but we've also verified the performance figures our researchers predicted when they first theorised that it might be possible to exploit interference to achieve faster and more efficient communications."
Lucent is working to speed the commercial introduction of MIMO technology by making its family of Flexent OneBTS base stations MIMO-ready. It believes the technology has the potential to greatly enhance the coverage, capacity and speed of 3G network
Lucent plans to license the chips' designs to mobile handset, PC card and other device manufacturers that may be interested in integrating MIMO into future products. The company is also working with 3G wireless standards groups to ensure that emerging MIMO standards support BLAST.
A Bell Labs research team in Sydney, Australia, designed the chips in collaboration with researchers at Bell Labs' Crawford Hill facility in New Jersey where BLAST was invented. The two chips, one for detecting BLAST signals and the other for decoding them, have been tested successfully in four-antenna terminal configuration that also uses four transmit antennas at the base station.
Lucent hopes different modulation schemes and antenna configurations can be used to achieve even higher data rates for future generations of BLAST chips. ®
How BLAST works
From Lucent's press release:
BLAST technology exploits a theoretical concept that many researchers believed was impossible. In most wireless environments, radio signals do not travel directly from transmitter to receiver, but are randomly scattered in transit before they reach the receiver. The prevailing view was that to have good reception, each of these signals needed to occupy a separate frequency, similar to the way in which radio or TV stations within a geographical area are allocated separate frequencies. Otherwise, the interference between stations operating on the same frequency would be too overwhelming to achieve quality communications.
But BLAST's inventors theorised, and later proved, that it is possible to have several transmissions occupying the same frequency band. Additionally, they realised that it is possible to use the scattering of these signals to enhance, rather than degrade, transmission accuracy by treating the scattered paths as separate, parallel sub-channels.
BLAST splits a single user's data stream into multiple sub-streams and uses an array of transmitter antennas to simultaneously launch the streams in parallel. All the sub-streams are transmitted in the same frequency band, so spectrum is used very efficiently. At the receiver, an array of antennas is again used to pick up the multiple transmitted sub-streams. Using the multiple antenna technique, the rate of transmission is increased roughly in proportion to the number of antennas used to transmit the signal.
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