National Legislation on Wireless (Radio) Communications Standards
Countries worldwide have national legislation on regulating radio use. Developers and manufacturers of products (electronic parts, IoT devices and products) outputting radio waves must comply with this legislation and require permission (certification) to sell such products. In addition, the various standards related to radio waves and radio equipment must be evaluated in accordance with these standards. These evaluation tests are handled by organizations, such as test houses and certification bodies as follows.
These are national and regional rules governing radio usage.
||Legal Organization with Jurisdiction
||Ministry of Public Management, Home Affairs, Posts and Telecommunications (Radio Law, etc.)
||Federal Communications Commission (FCC)
||European Commission (EC)
||State Radio Regulation Center (SRRC)
||National Radio Research Agency (NRRA)
2. Radio Communications Standards
There are standards organizations for the various radio communications methods, which determine the radio communications quality to be maintained.
Institute of Electrical and Electronics Engineers
|IEEE 802.11 a/b/g/n/ac/ax etc.
||Bluetooth Sig/Core Speciﬁcation 5.1
Bluetooth Special Interest Group
||3GPP Release 15 etc.
3rd Generation Partnership Project
||3GPP Release 15 etc.
3rd Generation Partnership Project
|5G NR (New Radio) sub-6GHz/mmwave
As an example, for WLAN there are also the CTIA/WFA CWG tests standards in addition to the wireless standards determined jointly by the Cellular Telecommunications Industry Association (CTIA) and Wi-Fi Alliance (WFA) established in North America.
These test standards regulate antenna performance evaluations in an Over The Air (OTA) environment using an anechoic chamber. They are used not only by North American carriers but are also used by carriers in the Asian region and have recently been adopted by European carriers; these standards cover both cellular and Wi-Fi operations and test items for each technology. They are targeted at evaluation of smartphones, tablets, and IoT gateways, etc.
These cellular and WLAN (Wi-Fi) tests must be performed in an OTA test environment using the Signalling mode.
4.2 Wi-Fi Desense Measurements with Cellular Transmitter ON
4.3 Cellular Desense Measurements with Wi-Fi transmitter ON
3. EMC/SAR, etc.
In addition to the legislation governing radio and the wireless communications standards, there are also rules, such as EMC, SAR etc., governing the effect of radio waves on the human body and other equipment.
The EMC International standards bodies are the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO), both of which also regulate SAR.
||EMC has EMI and EMS test.
||Electromagnetic interference generated by electronic products must have no impact on other products and systems.
||Other equipment and systems must operate normally even when receiving electromagnetic interference.
||Specific Absorption Rate
||Radio waves from electronic products must have no impact on the human body.
The standard is composed of two parts: Head-SAR, and Body-SAR.
4. Quality tests
In addition to the legislation and standards, each manufacturer performs strict tests (for example, the following test) on their products to improve the user experience.
At OTA testing using an anechoic chamber, evaluation of the product performance and functions is performed by configuring a multipath environment using radio-wave reflective boards (to approximate a realistic environment).
*Chamber: This is also called an RF chamber. It prevents interference from external electromagnetic radio waves while also blocking leakage of these waves to the outside and functions as a shielded room in which radio waves are not reflected inside.
*Multipath: In actual usage, radio waves do not follow a straight path and are bent and reflected by obstructions, such as buildings; the multiple paths followed by these reflected waves are called multipaths, resulting in interference and delay at the receiver side.
(Example) Multipath Test (OTA Test using Anechoic RF Chamber)
5. Increased demand for evaluation under realistic conditions
Recently, there has been increasing demand for OTA tests to evaluate performance and functions under realistic conditions. Additionally, there is also a need for Signalling-based evaluation.
Previously, conventional tests evaluated wireless signals by:
- Installing test software when necessary
- Connecting dedicated control cables to wireless communications chip and controlling chip (Direct mode)
- Connecting cable for measuring wireless signal (Non-OTA test)
This method not only greatly differs from the environment where IoT devices are used in a real environment, but, because it also does not assure wireless performance in the actual usage environment, it is subject to risks of claims from users, such as “I cannot connect, or I get disconnected” after commercial release, as well as problems with inability to reproduce the actual usage environment when investigating the cause of problems.
Due to these types of issues, evaluation requires:
- Testing without installing software
- Testing without physical connection to wireless chip (Signalling mode)
- Testing without connecting cables for measuring wireless signal (OTA tests)
With the growth of the IoT market,
in addition to the legislation and earlier standards for cellular communications, there is increasing demand for tests for various other radio communications standards, such as WLAN, Bluetooth, etc., as well as for EMC and SAR. In addition, there is also demand for OTA and Signalling tests.
As a consequence, IOT and equipment vendors as well as test houses are demanding support for these new tests.
6. Other precautions
A) Due to the installation position of the radio module, sometimes sending receiving may be abnormal due to shielding effects from other internal components, requiring design evaluation to prevent such problems.
B) The impact of internal noise (power supply noise) in IoT products can sometimes prevent normal sending and receiving of radio waves.
Interference generated by the equipment power supply, CPU board, LCD, etc., can have an adverse effect on radio communications.
C) Even when using radio modules with assured performance, sometimes the required performance cannot be obtained when upgrading the radio module, IoT device and product, etc., firmware.
As described above, developers and makers of device and products must pay sufficient attention to the legislation, wireless communications standards, EMC and SAR rules, and quality tests as well as to the other precaution contents. In addition, Signalling-based evaluations using OTA tests are required for implementing realistic tests according to the standards.
Makers developing and manufacturing IoT devices and products can assure IoT quality by following the above-described evaluations to distinguish their products from those of other inferior makers not performing communications quality evaluations to improve the value of their products for customers and achieve high-value brand recognition.
As well as reducing the future risk of customer warranty claims, such as inability to connect and disconnected connections, if a claim is made, the causes of problems can be resolved quickly by understanding product performance in an OTA environment.