There norm EN 300 328 concerns the good use of the radio spectrum and regulates the placing on the market of fixed and mobile equipment dedicated to data transmission in the 2.4 GHz band, such as WiFi, Bluetooth and Zigbee devices.
It specifies requirements to demonstrate that the radio equipment uses the radio spectrum effectively and supports the efficient use of the radio spectrum, in order to avoid harmful interference. It also describes what the spectrum access requirements are to facilitate sharing the spectrum with other equipment.
The application of the standard satisfies the essential requirements of article 3.2 of the Radio Directive 2014/53/EU and is harmonized in the Official Journal of the Directive.
The standard EN 300 328 is defined by ETSI (European Telecommunications Standards Institute) which is the body responsible for defining and issuing standards in the field of telecommunications in Europe.
Scope: The standard applies to data transmission equipment operating in the 2.4 GHz ISM band and using broadband modulation techniques; specifically, the equipment that operates:
• Transmission: Frequency bands 2,400 MHz to 2,483.5 MHz
• Frequency: Frequency bands 2 400 MHz to 2 483.5 MHz
Among the devices with wireless technology subject to the EN 300 328 standard there are:
- WiFi and Wireless LAN (WLAN) (access points, hotspots)
- WLAN equipment IEEE 802.11 b/g/n (access points, routers, notebooks, smartphones, tablets)
- Bluetooth and Bluetooth LE equipment (notebooks, smartphones, tablets, mice, wireless audio devices, headphones)
- WPAN equipment IEEE 802.15.4™ Low-Rate Wireless Personal Area Networks (remote controls, sensors)
- Zigbee (wireless switches, electricity meters, smoke and intrusion alarms, home automation devices)
TECHNICAL REQUIREMENTS OF THE STANDARD
The standard requires a functional approach to new technologies that adopt it as a harmonized reference, entering into the merits of the occupied band and out-of-band transmission, but also of concepts such as adaptivity and modification of the duty cycle, which are required to be highlighted with specific tests.
RF power output
RF (radio frequency) output power is defined as the average equivalent isotropic radiated power (eirp) of the equipment during transmission burst.
The maximum allowed limit is -10 dBW (20 dBm, 100 mW).
Power spectral density
This is the average equivalent radiated isotope power spectral density during a transmission burst.
The value is limited to 10 dBm per MHz.
This is the band that contains the 99% signal strength.
It must fall completely within the 2.4GHz to 2.4835GHz band.
Transmitter unwanted emissions in the out-of band domain
Unwanted transmit emissions in the out-of-band domain are emissions that result from the modulation process (excluding spurious emissions) when the equipment is in transmit mode, on frequencies immediately outside the required band.
Transmitter of unwanted emissions in the spurious domain
Unwanted transmit emissions in the spurious domain are emissions that occur outside the assigned band and out-of-band domain when the equipment is in transmit mode.
Receiver spurious emissions
Spurious receive emissions are emissions at any frequency detected when the equipment is in receive mode.
This is a measure of the equipment's ability to receive a signal in its operating channel without exceeding a given degradation in the presence of unwanted signals (blocking signal) at frequencies different from those of the operating band.
The minimum performance criterion is less than or equal to 10%.
Main contents of the standard
For a correct testing of radio equipment operating in the 2.4 GHz band, the technical requirements indicated in the standard are divided into two main types of broadband equipment:
- equipment FHSS (Frequency Hopping Spread Spectrum)
- equipment with broadband modulation other than FHSS
For equipment using the transmission technique FHSS, the standard provides two options for verifying compliance with the requirements, one of which is based on the probability of employment for each frequency.
By frequency occupancy (Frequency Occupation) means the number of times each band is occupied in a given period of time.
The standard also describes the requirements for emissions Out of Band (OOB) and defines the frequency range that extends for double the band used, around the operating frequency. For spurious emissions, the standard requires the use of high resolution points during the sweep, in order to obtain accurate data.
Products operating in the 2.4 GHz band are often susceptible to interference from other equipment using the same frequency band.
The EN 300 328 standard defines “adaptivity” as the mechanism by which the equipment can adapt to the environment by identifying other transmissions in the band.
The test methods described in the standard aim to verify how the equipment adapts to the environment, identifying other transmissions present in the band and adapting its frequencies and operating channels selected by excluding other transmissions.
Adaptive equipment must therefore be able to detect interference and stop transmission when interference is detected.
The adaptive aspect is part of the requirements for spectrum sharing.
The standard defines different categories of receivers with related requirements and/or limits:
- Receiver Category 1: Adaptive equipment with maximum RF power greater than 10 dBm EIRP
- Receiver category 2: non-adaptive equipment with a factor of Medium Utilization (MU) greater than 1% and less than or equal to 10% or adaptive equipment with a maximum RF power of 10 dBm EIRP
- Receiver category 3: non-adaptive equipment with a factor of Medium Utilization (MU) maximum of 1% or adaptive equipment with maximum RF power of 0 dBm EIRP
The aspects covered by the standard are broad and particularly detailed and require, in addition to specific competence and preparation, also a certain experience in the field. Relying on an expert laboratory like Sicom Testing simplifies the testing process for certification of radio equipment operating according to the main telecommunications standards and substantially reduces verification and control times.
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