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Summary:

QAM has shaped the waveforms in our communications networks for 40 years, but MagnaCom has developed an alternative modulation scheme that it claims will revolutionize speed, capacity and power efficiency on wireless and wireline networks.

To say southern California startup MagnaCom wants to shake up mobile and wireline communications would be an understatement. The company is proposing that cellular, Wi-Fi, fiber and wireline broadband networks do away with one of their fundamental technological underpinnings — an age-old modulation scheme called QAM.

QAM stands for quadrature amplitude modulation, and it’s a means of manipulating signals so they carry information over communications links, whether it’s the episode of Sesame Street coming out of your cable box or the Twitter update popping up on your smartphone.

Improvements in that modulation scheme have led to big improvements in spectral efficiency, meaning the same signals can carry more information. For instance, you may have heard mention of QAM in reference to mobile technologies: the boost from 16 QAM to 64 QAM was one of the means used to turn HSPA networks into faster HSPA+ networks.

MagnaCom WAM logoBut MagnaCom founders CEO Yossi Cohen, who has headed up mobile communications at both Motorola and Broadcom, and CTO Amir Eliaz, the communications scientist who developed  MagnaCom’s technology, believe that QAM has seen its best days. On Tuesday, they brought their company out of stealth mode with an audacious proposal: an alternative modulation scheme they call Wave Modulation, or WAM.

How WAM works is pretty geeky stuff, and I’ll admit it’s beyond my basic technical understanding. But for the engineers out there, here’s MagnaCom’s explanation:

WAM technology uses spectral compression which improves spectral efficiency. The spectral compression enables an increase of the signaling rate (e.g. by 2x) thereby affording the use of lower order alphabet (e.g. a 64 constellation alphabet instead of 4096), which reduces complexity. It provides inherent diversity of time and frequency domains and uses nonlinear signal shaping and adaptive nonlinear model learning. The nonlinearities are handled digitally at the receiver side, allowing a lower-cost and lower-power transmitter design.

The bottom line, though, is that MagnaCom claims it’s created a more efficient modulation scheme, one that can pack more information into the same spectral real estate, meaning that the same data could be transmitted at higher speeds, lower power and over less spectrum or fewer cables than required today. According to the company, WAM could produce a 10dB gain in a communications system, which could translate into 400 percent increase in range, a 50 percent decrease in power or 50 percent drop in frequency bandwidth over today’s QAM-based systems.

If its claims are true that would be a tremendously significant advancement in communications technology. Of course, MagnaCom has to prove the technology’s merits to the communications industry and make it commercially viable. It plans to do the first at CES next month in Las Vegas, partnering with programmable logic device maker Altera to build a live WAM demonstration platform at the trade show.

MagnaCom WAM diagram

As for making the technology viable, MagnaCom claims that WAM will be easy to implement. Its modulation scheme is purely digital, so it will work over the same analog components, radios and antennas already in devices and infrastructure today, and it’s fully backward compatible with QAM. WAM will require changes to communications semiconductors, but MagnaCom said the technology would consume 1 square millimeter of silicon space in modern communications chips.

  1. One of the shortcomings of “QAM-OFDM” is the seemingly excessive frame-time required to convey a useful range of QAM symbols carried on a plurality of closely offset sub-carriers, which are interfering with each other for all but a short readable moment during each frame.

    “QAM-OFDM” signals are not efficient because most of the time and energy consumed by the aggregate signal is spent with the sub-carriers in contention with one another and not conveying readable modulation.

    WAM should be a welcome refinement to “QAM-OFDM”.

    DJROCK.com

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