Almost all wired and wireless applications today use the QAM or Quadrature Amplitude Modulation. These include the Fiber infrastructure, Wireless Backhaul, DSL modems, Cable modems, Cable TV, Satellite TV, Wi-Fi, Cellular and numerous other communication systems.
QAM systems use two AM or Amplitude-Modulated signals combined into a single channel – increasing the effective data rate while using the same amount of bandwidth. A QAM signal has two carriers, each with the same frequency, but differing in phase by 90 degrees. The term quadrature arises from the difference of one quarter of a cycle. If you call one of the amplitude-modulated signals the in-phase signal, the other becomes the quadrature signal.
Typically, the quadrature signal, multiplied with a sine wave, is subtracted from the in-phase signal multiplied with a cosine wave. The resulting signal is then amplified and transmitted over the air, wires or cables.
At the destination, a reversal of operations takes place by multiplying the in-phase output by a cosine wave and the quadrature output by a sine wave. Filtering them individually leaves only the lower frequencies. As these operations are entirely reversible, they ensure the preservation and exact recovery of the originally transmitted data.
Proliferation of communications devices and systems is putting considerable stress on bandwidth availability. For the past 40 years, QAM has completely dominated the advanced communication systems. Consequently, there are over seven billion connected devices using QAM technology.
Lately, a new Wave Amplitude Modulation or WAM technology is challenging this dominance of QAM. MagnaCom, who has patented and trademarked the WAM technology, claims the use of WAM can enhance nearly all wired and wireless applications. Additionally, WAM being backward compatible to legacy QAM systems, its use will not require any changes to the RF, radio or the antenna.
WAM technology uses a purely digital modulation scheme and is scalable. While using the same analog and RF circuits that QAM does, WAM needs no redesign and consumes only about one square millimeter space in modern semiconductor design. As the WAM technology is scalable, designers can now implement a smaller and lower cost solution.
Speaking technically, WAM represents a multi-dimensional signal construction technique working in the Euclidean domain. For the first time, designers can break the orthogonal signal construction. This provides an optimal handling of nonlinear distortion, increasing the system capacity. Overall, there is significant improvement over the legacy QAM systems.
The benefits of using WAM include a system gain advantage of over 10dB, while increasing the distance covered by over four times at half the power. This results in double the spectrum savings, offering better noise tolerance, major increase in speed and easier design at lower costs. Additionally, there is no need to replace any of the existing QAM equipment, as WAM is entirely backward compatible with QAM.
Compared to QAM, the new technology modulates information differently resulting in major system benefits. The use of spectral compression allows WAM to improve spectral efficiency by enabling an increase of the signaling rate. This allows reduction of complexity to a lower order. The use of nonlinear signal shaping by WAM offers inherent diversity of time and frequency domains, resulting in a lower cost and lower power design of the transmitter.
