Flexibility in over‐the‐air testing of receiver sensitivity with reverberation chambers

Abstract

The next generation of wireless device utilises higher frequencies and a large array of form factors. With miniaturisation of devices and the growth of internet‐of‐things applications having no connectors for testing, the use of conducted tests is no longer an option and verification of this equipment requires over‐the‐air measurements. Additionally, some important metrics such as receiver sensitivity requires an actual communication link. Reverberation chambers loaded with lossy absorbers provide an efficient environment to measure such averaged quantities with flexibility in a test volume as well as device size, shape, and placement. Here, the authors present an overview of OTA measurements in reverberation chambers compared to anechoic measurements. The authors show the consistency and flexibility of reverberation chambers through measurements of a wireless device in three different reverberation chamber setups and compare to an anechoic chamber measurement. By using a proper chamber setup, and by showing a coherence bandwidth (CBW) as a universal metric for comparing chamber loading between setups, excellent chamber‐to‐chamber consistency is shown, without precise placement of the device in each chamber. The authors show empirical evidence for the choice of threshold in determining the CBW.

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

“…where c is the speed of light, f is the test frequency, and G REF is the reference power transfer function of the chamber in (1). Note that B C is applicable to the case that the coherence bandwidth is defined as the bandwidth over which the complex correlation function has decreased from 1 to 0.5 [28].…”

“…The application of wireless-Internet-of-Things (W-IOT) is currently being widely adopted in our daily lives. Consequently, over-the-air (OTA) tests of wireless devices have attracted considerable attention from both industry and academia [1][2][3][4][5][6]. The reverberation chamber (RC) is an electrically large conducting cavity with various mode-stirring mechanisms to create a random and statistically homogeneous environment [6][7][8].…”

NB-IoT devices in reverberation chambers: a comprehensive uncertainty analysis

“…The performance of these cellular devices is often studied with over-the-air (OTA) tests by metrics such as Total Isotropic Sensitivity (TIS) and Total Radiated Power (TRP) [4–9]. These tests can be carried out either in an anechoic chamber (AC) or a reverberation chamber (RC).…”

“…These tests can be carried out either in an anechoic chamber (AC) or a reverberation chamber (RC). An RC is a large metal cavity, with one or more mode-stirring mechanisms to produce, on average, a uniform distribution of the fields, and can often produce faster, lower-cost, or more flexibly configurable measurements than an AC [4]. This makes an RC an excellent candidate for testing IoT devices when directional information is not required.…”

“…RCs have been researched extensively and were shown to be suitable for TIS measurements on earlier-generation protocols, such as W-CDMA (4 MHz channel bandwidth) [4–9]. However, for NB-IoT, we expect additional challenges due to the narrowband nature of this protocol (180 kHz channel bandwidth).…”