Saraband Wireless press release
For Immediate Release:
Wireless Communications Enhanced by Newly Patented Propagation Technology
(Fairfax, Virginia, June 7, 2007) Saraband Wireless Inc., (Saraband) established to advance the capabilities of broadband wireless devices and systems, recently announced the company has received a U.S. patent on a ground-breaking propagation approach that significantly enhances the performance of broadband wireless communications.
The Saraband technical solution dramatically improves radio frequency (RF) data transmissions between communicating devices by continuously measuring and adjusting for channel state propagation path conditions. Conducted with an inventive self-correcting feedback loop that synchronizes crystal oscillators in distant devices with atomic-like accuracy, the Saraband solution considerably improves the throughput and reach of non-line-of-sight (NLOS) broadband communications.
Saraband’s advanced technical approach to signal propagation overcomes many of the performance and penetration problems of existing wireless Internet Protocol (IP) packet transmitting systems, while greatly extending the effective range and allowing for considerable reduction in the infrastructure costs of broadband wireless communications.
As a supplemental “propagation analyst” on a chip application, the Saraband solution can be used to enhance a wide variety of WiFi, WiMax and other wireless broadband platforms. Tested and verified under grants from the National Science Foundation, wireless NLOS broadband signals were successfully transmitted utilizing this system at a range that exceeded 13 miles. Developed by wireless and satellite industry pioneers, Drs. Donald Arnstein, and Paul Ebert, (who first collaborated as MIT Graduate students), the Saraband communications solution expands upon the concept and capabilities of traditional vector network analysis devices, which measure the conveyance and distortions of electromagnetic signals transmitted through electronic filters. The Saraband Vector network analyzer appliqué (VNAA) applies a unique and now patented feedback system that aligns low cost crystal oscillators positioned miles apart, permitting an accurate determination of the propagation path in just a fraction of a second.
In describing the Saraband technology, Donald Arnstein, the President of Saraband remarked; “We took the traditional vector network analysis function and figuratively speaking split it into two widely separated halves so the test signal injector and test signal receiver can be miles apart, miniaturized, and made an integral part of a communications link. With the use of repetitive 'pinging signals' hidden away between and under information-bearing signals, this technique provides a very neat situational awareness of channel state conditions."
Over-the-air vector analysis, which had previously
been accomplished only with the help of atomic rubidium and cesium
frequency standards, provides for discovery of highly accurate amplitude
and phase distortion versus frequency going on in the channel, a
characterization needed to describe multipath in doppler fading channels
typical of broadband wireless systems. Through the use of unobtrusive
channel sweeping signals generated at the transmission point and
captured at the receiver, continual measurements of amplitude versus
frequency and phase shift versus frequency characteristics are made.
These dynamic measurements are combined with an adaptive processing
circuit to adjust the network to match the conditions actually there.
The various methods used today suffer from requests for retransmission
and intermittent quality of service failures in fringe regions of
coverage. Using Saraband's technique, the network can adapt its
transmission data rate, its selection of modulation and forward error
correcting coding, and its transmission frequency band. The same channel
state measurements are also concurrently conveyed to an adaptivity
function at the receiving end to select and adjust demodulator variables
such as gain control, and equalization of amplitude and phase, versus
frequency. According to Saraband ‘s developers, this is more efficient
and effective than the current leading WiFi and WiMax 802.11 and 802.16
methods of gaining information about channel conditions. In particular,
the pilot tone method used by WiMax cannot tell the difference between
phase error caused by channel multipath and phase error caused by
oscillator drift.
Commenting on the Saraband invention, Dr. Raymond L. Pickholtz said, "While most modern wireless communications do possess means for doing channel state measurements, they are usually restrictive (measure only phase), do non-integrative measurements, are designed for the ad-hoc conditions of the signals used, are not scaleable or adaptive to variable and higher data rates, not coordinated to higher (MAC) layer, and generally do not provide for rapid and very accurate measurement that is necessary for modern and future broadband wireless applications." Dr. Pickholtz also commented on the mechanisms for channel measurement that were described in the patent, as follows: "The speed/performance improvement may be very significant at higher data rates and may allow operations at distances and data rates that would not otherwise be possible."
In summary, by creating highly accurate situational awareness of a channel state’s propagation conditions, Saraband’s VNAA is a value-add solution that could work in combination with any current physical layer modulation technique. Whether a system is utilizing WiFi or WiMax, or is still on the drawing board, the Saraband solution will permit more rapid and efficient allocation of resources.