Measurement uncertainty of RC and its reduction techniques for OTA tests: a review

Abstract

The emerging machine‐to‐machine (M2M) communications and Internet‐of‐things techniques bring new challenges in over‐the‐air (OTA) tests. The inexpensive M2M device usually aims at low‐cost and low‐power consumption rather than high data rate and, therefore, is usually equipped with a single antenna. Testing such M2M device in massive production requires efficient and cost‐effective OTA techniques. The reverberation chamber (RC) is a suitable solution for such tests of M2M (especially large‐form‐factor) devices. Since RC measurements are in essence stochastic measurements (with repeatable results), uncertainty analyses are of primary importance. This study gives an overview of the start‐of‐the‐art research on measurement uncertainty for both conventional and M2M OTA applications. In addition, new results about mode stirrers and diffusers (for uncertainty reduction) are provided.

Statistical analysis of measurement uncertainty in total radiated power of wireless devices in reverberation chamber

“…where N S tot represents the total stirring numbers (here N S tot = 100), δ represents the offset when the autocorrelation coefficient of the samples has dropped to a specified threshold, and the autocorrelation coefficient and threshold can be obtained using (12) and (13), respectively,…”

“…In addition to the usual uncertainty contributions when conducting an antenna measurement, the RC's stochastic property can contribute to the uncertainty as well. The measurement uncertainty of the RC has been extensively studied in the literature [13][14][15][16][17][18][19][20][21][22][23][24]. Nevertheless, most of these studies are confined to passive measurements, except for [22][23][24] where the TRPs of active wireless devices were measured.…”

Research on OTA Testing Optimization of 5G IoT Devices

“…For applications in which global coverage and mobility are major concerns, cellular technologies, especially LTE-M and NB-IoT are preferred technologies. Meanwhile, the majority of devices use non-cellular technologies including Bluetooth, Wi-Fi, ZigBee, EnOcean, SIGFOX, LoRa and others [6][7][8][9][10][11][12][13]. Wireless connection reliability, coverage, response speed and security are factors which heavily impact quality of experience and system performance, which in turn depends on agile and highperformance antennas.…”

Average Rician K-Factor Based Analytical Uncertainty Model for Total Radiated Power Measurement in a Reverberation Chamber

“…So far, Numerous studies have been conducted in this field [9], [11], [13], [14], [19]- [27]. It is commonly accepted that for a practical RC that inevitably renders nonzero unstirred power, the corresponding measurement uncertainty dependents not only on the finite number of independent samples [9], [19], but also on the limited spatial uniformity [11], [20]- [26]. Sometimes, the latter can even dominate the uncertainty [21].…”