“…Equal-gain systems can successfully increase the signal strength at their output only if the noise signals are uncorrelated and the data signals are correlated, as already pointed out by [ 20 ]. If there is a highly correlated noise signal present at the antennas, equal-gain-combining systems degrade in their performance and selection diversity can achieve a higher signal-to-noise ratio of the output signals then the other techniques.…”
Small scale fading signals resulting from multipath propagation can cause signal strength variations in the range of several dB. Resulting from the fluctuating signal strengths, the wake-up packet reception rate can decrease significantly. Using antenna diversity can greatly mitigate these effects. This article presents a novel wireless sensor node with wake-up receiver that uses an equal-gain diversity method with two antennas in the wake-up path. Summation of the two diversity branch signals is done after the passive demodulation of the incoming signals. As a result, the wireless sensor node requires almost no additional active parts that would increase power consumption. Furthermore, we demonstrate experimentally the improved wake-up robustness and reliability achieved by this diversity technique in a multipath environment.
“…Equal-gain systems can successfully increase the signal strength at their output only if the noise signals are uncorrelated and the data signals are correlated, as already pointed out by [ 20 ]. If there is a highly correlated noise signal present at the antennas, equal-gain-combining systems degrade in their performance and selection diversity can achieve a higher signal-to-noise ratio of the output signals then the other techniques.…”
Small scale fading signals resulting from multipath propagation can cause signal strength variations in the range of several dB. Resulting from the fluctuating signal strengths, the wake-up packet reception rate can decrease significantly. Using antenna diversity can greatly mitigate these effects. This article presents a novel wireless sensor node with wake-up receiver that uses an equal-gain diversity method with two antennas in the wake-up path. Summation of the two diversity branch signals is done after the passive demodulation of the incoming signals. As a result, the wireless sensor node requires almost no additional active parts that would increase power consumption. Furthermore, we demonstrate experimentally the improved wake-up robustness and reliability achieved by this diversity technique in a multipath environment.
“…EGC adds the co-phased branch signals. In MRC, the phase weights are applied to each branch such that the output will be the sum of their SNR ratios [ 49 , 50 ]. Fig.…”
“…In severe multipath fading scenarios, e.g. underneath dense foliage, reception with a single antenna can be strongly impaired [4,5], as their signal-to-noise ratio (SNR) history (red and orange line) drafted in Fig. 1 shows along the driving path.…”
For a fast scan-phase satellite radio antenna diversity system a noise correction method is presented for a significant improvement of audio availability at low signal-to-noise ratio (SNR) conditions. An error analysis of the level and phase detection within the diversity system in the presence of noise leads to a correction method based on a priori knowledge of the system's noise floor. This method is described and applied in a hardware example of a satellite digital audio radio services antenna diversity circuit for fast fading conditions. Test drives, which have been performed in real fading scenarios, are described and results are analyzed statistically. Simulations of the scan-phase antenna diversity system show higher signal amplitudes and availabilities. Measurement results of dislocated antennas as well as of a diversity antenna set on a single mounting position are presented. A comparison of a diversity system with noise correction, the same system without noise correction, and a single antenna system with each other is performed. Using this new method in fast multipath fading driving scenarios underneath dense foliage with a low SNR of the antenna signals, a reduction in audio mute time by one order of magnitude compared with single antenna systems is achieved with the diversity system.
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