WLAN devices need to conform to Regulatory domain or country requirements for Transmit power/spectral mask and channel allocation. A regulatory domain might be a country or a set of countries which might follow similar laws for channel utilization. For e.g. The EU regulatory domain is for Europe (a set of countries) The US regulatory domain […]

The Country Information element is shown below Fig Courtesy: 802.11 Standard where dot11OperatingClassesRequired is False and the First Channel Number/Operating Extension Identifier octet has a positive integer value of less than 201, then the  Country Information element is shown as below Country String – indicates the country of operation. It also indicates Indoor/Outdoor operation (e.g […]

The Country Information element is shown below Fig Courtesy 802.11-2012 standard where dot11OperatingClassesRequired is true and the First Channel Number/Operating Extension Identifier octet has a positive integer value of 201 or greater, then that triplet comprises the Operating Extension Identifier, Operating Class, and Coverage Class fields Operating Extension Identifier – indicates whether the Sub-band triplet […]

An 802.11 Station on entering a new regulatory domain will not initiate an active scan (i.e. send probe requests). It will passively listen till it receives a beacon which contains the Country Information element. On reading the Country Information element and ascertaining the country of operation – the device can later scan actively for an […]

Some portions of the 5 GHz WLAN band is used by Radar, Weather satellites and other sensitive applications. The regulatory authorities of different countries determine on how transmission is to be attempted on these channel by WLAN devices. If transmission of any sensitive application is detected, the WLAN device should not attempt further transmission on […]

The current article tries to elaborate on how the Access Point notifies client stations on the presence of radar and the steps it employs to detect radar An access Point will periodically quiet the entire BSS to scan for radar. This is achieved by transmitting the quiet element in the beacon The quiet element can […]

The Extended channel switch element is used when dot11ExtendedChannelSwitchActivated is true. The Extended channel switch element can be transmitted in an Extended Channel switch announcement frame by the Access point or in a beacon. In addition to the regular Channel switch announcement Element parameters, the extended channel switch announcement element provides the operating class of […]

Radar signals can broadly be classified as Pulse signal Chirp signal Frequency-hopping signal The FCC/ETSI/JP and other regulatory bodies define their own version of the above signals. Below is given an overview of FCC signals and their widths and also provide minimum percentage number of successful detection of the radar signal for the FCC to […]

As seen in the Previous article — <Radar Signals and it’s signatures>, The different radar signals have a repetition rate. The number of successful detection is based on the 802.11 PHY layer detecting the signal (such as a pulse/chirp/frequency-hopping radar signal) and providing the input to the upper layer driver (via a phy error – […]

802.11n introduced channel bonding. An 802.11n station/AP will indicate the support for 40 MHz operation in the HT capabilities Information element. The information element and the particular bit that indicates 40 MHz support is shown below  Fig Courtesy: 802.11 standard The Wireless Capture below shows the Supported channel width setting The Access point in the […]