Audio quality measurements for wireless microphones in spectrum pooling scenarios

In this contribution the influence of different broadband OFDM schemes on the perceptual audio quality of narrowband wireless microphone links is evaluated, since coexistence scenarios of wireless microphones and Orthogonal frequency-division multiplexing (OFDM) based services arise in the TV bands. Therefore, we present different non-contiguous cyclic-prefix (CP-)OFDM and offset quadrature amplitude modulation (OQAM-)OFDM system designs based on the spectrum pooling concept. We measure their power suppression in the subchannel allocated for the wireless microphone. As an indicator of the perceptual audio quality, we measure the objective difference grade of a colored noise audio signal emitted over a consumer-like hardware. The measurements show that the non-contiguous OQAM-OFDM scheme not only introduces lower interference to the FM link, but also has the advantage of requiring less number of notched carriers in comparison to CP-OFDM. By application of non-contiguous OQAM-OFDM with an appropriate number of notched carriers instead of the classical CP-OFDM scheme, wireless microphone systems can still sustain a significant low SIR when non-professional hardware is applied.