Lucent Technologies' Chips Poised to Bring "BLAST" Multiple Input/Multiple Output Technology to Laptops, PDAs and Other Mobile Devices
Lucent Technologies today announced that Bell Labs, its research and development arm, has designed two prototype chips for mobile devices that implement its multiple input/multiple output (MIMO) wireless network technology, called Bell Labs Layered Space-Time (BLAST). These chips, which conform to industry standards for size and power consumption, demonstrate that BLAST technology can be deployed in mobile devices commercially. In initial lab testing, the chips lived up to theoretical predictions, receiving data in a third-generation (3G) mobile network at a blazing 19.2 Megabits per second (Mbps). By comparison, today's fastest 3G networks, offer maximum speeds of roughly 2.5 Mbps.
BLAST uses multiple antennas at the terminal and base station to send and receive wireless signals at ultra-high speeds. When utilized in base station equipment and mobile devices, it permits higher-speed mobile data connections for notebook PCs and handheld data devices such as personal digital assistants (PDAs). This will enable mobile operators to provide higher-quality, higher-speed data services to a substantially greater number of subscribers than is possible with the best 3G network technology available today, increasing the value of their 3G investment dramatically.
"There has been a scramble around the world to put MIMO in silicon," said Ran Yan, vice president, Wireless Research at Bell Labs. "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. Not only have we proven the commercial feasibility of BLAST, but we've also verified the performance figures our researchers predicted when they first theorized that it might be possible to exploit interference to achieve faster and more efficient communications."
Lucent is also working to speed the commercial introduction of MIMO technology by making its family of Flexent(R) OneBTS(TM) base stations MIMO-ready. By doing so, a base station purchased today will provide mobile operators with a cost effective and seamless way to support this technology in the future when MIMO-enabled mobile devices become commercially available.
"The development of these chips offers tremendous promise as a key element of our effort to help our customers extend the value of their existing infrastructure investments," said Paul Mankiewich, chief technical officer of Lucent's Mobility Solutions Group. "This technology has the potential to greatly enhance the coverage, capacity and speed of 3G networks."
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 originally invented. The two chips have been tested successfully in four-antenna terminal configuration that also uses four transmit antennas at the base station. These chips, one for detecting BLAST signals and the other for decoding them, are small enough and consume so little power that they could be used in cell phones or laptop computers with minimal impact on battery life.
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. Building on its success to date, the Bell Labs team also plans to use different modulation schemes and antenna configurations to achieve even higher data rates for future generations of BLAST chips.
How BLAST Works
BLAST technology essentially 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 theorized, and later proved, that it is possible to have several transmissions occupying the same frequency band. Additionally, they realized 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.