Download this article in .PDF format
This file type includes high resolution graphics and schematics when applicable.

As these standards continue to advance in frequency, bandwidth, and complexity, new and more versatile test and measurement equipment is necessary to characterize and refine the designs of complex communication structures. National Instruments proposes a solution to the complex LTE-A test scenario with its new PXI Express-based vector signal transceiver (VST). This transceiver is a software-programmable combination of a signal analyzer and generator in a PXI package. Agilent Technologies also offers a variety of LTE-A test and measurement solutions in a PXI Express platform.

Communications Continues To Inspire Technology Advances, Fig. 3

The evolution toward enhanced standards and resulting increase of RF-component performance is one way to meet the demands of next-generation communications systems. Yet companies like MagnaCom are looking deeper into the root of communication methods to squeeze the most out of already congested communication systems. MagnaCom’s technology, dubbed WAve Modulation (WAM), describes a method of digital modulation that takes a huge advance over the omnipresent quadrature amplitude modulation (QAM) with the same spectral mask. QAM is based on a system of two modulated signals that must operate within the linear region of the RF components with only a two-dimensional (2D) constellation of possible phases for the two signals. In contrast, WAM is designed from the bottom up to assume nonlinearity and multidimensional signal constellations. Because this modulation is purely digital, it does not require any hardware adaptations, is not a compression algorithm, and is a purely backward-compatible replacement of QAM (Fig. 3).

Nonlinearities like white noise, phase intermodulation distortion (PIM), and the nonlinear region of amplifier operation are accounted for automatically with WAM and do not degrade performance, according to Yossi Cohen, CEO of MagnaCom. WAM could allow for PAs and other RF electronics to operate beyond their normal region of linearity, allowing for wider dynamic range from the same hardware. This leads to a proposed benefit of up to 10 dB for the same footprint as a similar QAM4096 system. With higher spectral compression, a WAM system could offer increased signal rates over a QAM system at much lower-order constellation alphabets (64 with WAM compared to 4096 with QAM). WAM also benefits from the same scalability as QAM, increasing in operational performance as the order gets higher in the constellation alphabet.

According to the company, WAM could enable higher system gains, lower power, a boost in range, an increase in throughput, and lower-cost digital designs. The benefit for the designer is that he or she could choose per application. This technique also could provide a solution to the phase-noise issues present at much higher carrier frequencies. MagnaCom is currently looking to apply its technology in point-to-point systems like wireless backhaul, military, and satellite communications.

Download this article in .PDF format
This file type includes high resolution graphics and schematics when applicable.