Figure - available from: IET Microwaves, Antennas & Propagation
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Photograph of one of the reverberation chamber setups used for the data presented in this manuscript. This is the single paddle chamber with the automated, simultaneous measurement of Gch and PBSS. The DUT's antenna also serves as the reference antenna
Source publication
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. Additionall...
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Citations
... A key requirement is always high reliability, which makes testing necessary. In the last years, reverberation chambers (RCs) could be established as test environments for electromagnetic compatibility (EMC) testing with a corresponding standard IEC 61000-4-21 [2] or for antenna measurements [3][4][5] or over-the-air (OTA) evaluation of wireless devices with integrated antennas [6][7][8][9]. In [6], the general use of RCs for wireless device tests was proposed and in [7], different methods for sensitivity measurements were suggested. ...
... In [6], the general use of RCs for wireless device tests was proposed and in [7], different methods for sensitivity measurements were suggested. More than a decade later, [8,10,11] present comprehensive overviews of RC measurements, and finally [9] describes an OTA performance evaluation test plan for large-form-factor devices. ...
... As described, for example, in [8,9,12,17,39], a too narrow CBW can cause an increased PEP. Thus, typically, the CBW is increased for sensitivity testing by carefully adding RF absorbers to the RC (i.e., loading the RC) [8,9,12,17]. ...
Communication reliability is a challenging requirement, which implies the need for over-the-air (OTA) testing. Reverberation chambers (RCs) are widely used for OTA tests in various fields. Due to their properties, such as inherent radio channel emulation or the arbitrary orientation of the equipment under test (EUT) in the test volume, they can be used as advantageous test environments for wireless products in the field of industrial manufacturing automation, such as for the IO-Link Wireless (IOLW) standard. In this paper, the different OTA sensitivity test procedures total isotropic sensitivity (TIS), average fading sensitivity (AFS) and mean channel packet error (MCPE) method, which is based on the fundamental channel model of the wireless standard, are described and evaluated in various variants. A core aspect of the proposal is the impact of the possible use of frequency hopping of the wireless equipment under test. The respective advantages and disadvantages are shown. Overall, TIS proves to be a suitable alternative for IOLW OTA sensitivity testing.
... In order to calculate TIS using reverberation chambers (RCs), the device sensitivity is sampled over many steppedmode-stirring (or tuning) states [5][6][7][8][9][10][11][12] and the formula to calculate TIS can be derived the same way as for anechoic chambers [7]. Application of RCs to evaluate TIS was introduced almost 30 years ago and today the use of RCs for both TRP and TIS measurements is widely adopted [13]. ...
... Whereas Table II focused on results when all 165 continuous mode samples were used, Table III illustrates the results obtained considering a 1.0 dB standard uncertainty threshold (6), which is of interest to the CTIA as they consider relaxing the uncertainties for certain types of IoT device measurements. Recall that the 1.0 dB threshold value is represented by a square () in the plots in Fig. 5. ...
We present a method that allows a fast evaluation of total isotropic sensitivity with the use of continuous-mode stirring in a reverberation chamber. A limited number of standard stepped-mode measurements are taken to calibrate the continuous-mode measurements by computing the offset between the measured sensitivity level of the device and the device-reported reference signal received power. A comparison of the results from the method proposed here and the standard stepped-mode approach illustrates that the measurement results of the fast approach can be within 0.2 dB to 0.5 dB of the standard method and allows for a test time reduction of up to 90 %.
... 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][5][6][7][8][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][5][6][7][8][9]. However, for NB-IoT, we expect additional challenges due to the narrowband nature of this protocol (180 kHz channel bandwidth). ...
New protocols related to Internet-of-things applications may introduce previously unnoticed measurement effects in reverberation chambers (RCs) due to the narrowband nature of these protocols. Such technologies also require less loading to meet the coherence-bandwidth conditions, which may lead to higher variations, hence uncertainties, across the channel. In this work, we extend a previous study of uncertainty in NB-IoT and CAT-M1 device measurements in RCs by providing, for the first time, a comprehensive uncertainty analysis of the components related to the reference and DUT measurements. By use of a significance test, we show that certain components of uncertainty become more dominant for such narrowband protocols, and cannot be considered as negligible, as in current standardized test methods. We show that the uncertainty, if not accounted for by using the extended formulation, will be greatly overestimated and could lead to non-compliance to standards.
... The application of wireless-internet-of-things (W-IOT) are 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]- [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]- [8]. ...
Due to the explosive increase of wireless devices, efficient over‐the‐air testing of such devices is highly desirable. The reverberation chamber (RC) offers efficient and cost‐effective means to determine performance metrics of wireless devices, such as total radiated power (TRP). In this study, the distribution of the measured TRP in an RC is analytically derived, based on which the statistics (i.e. mean, variance) of the measured TRP are derived as well. RC measurements have been performed to verify the analytically derived statistics.
Internet of things (IoT) devices are proliferating in our connected world, with the number of devices expected to exceed 14 billion in 2023
[1]
. Wireless IoT applications are increasing day by day, ranging from cellular-enabled parking meters that can validate your credit card in real time, to trash compactors that inform the garbage company when they are full, to wireless local-area-network–enabled industrial programmable logic controllers (PLCs) that control robots on the factory floor with micron precision. The physical size and shape or
form factor
of these devices can range from millimeters to meters on a side, and latency requirements can range from hours (e.g., trash compactor) to seconds (e.g., parking meter) to milliseconds or less (e.g., factory floor sensing and control). With all of the possible variations, it is important to have flexible yet accurate test facilities for these devices.
Reverberation chambers (RCs) can be used as
repeatable and shielded test environments for electromagnetic
compatibility testing and performance evaluation of wireless communication
devices, as they inherently emulate a Rician/Rayleigh
fading environment. Loading a RC with radio frequency (RF)
absorbing material leads to an increasing coherence bandwidth
(CBW) of the radio channel within the RC, where the appropriate
value can be tailored to specific test specifications. In this paper
the CBW is directly measured by the wireless system under
test. Measurements were carried out with different loadings
and the link quality indication (LQI) was used to determine
an appropriate RC loading.
