We will now take a look at the frame formats of the different frames that are transmitted in a Block ACK session negotiation and termination. The Three frames that are used in the Block Ack session negotiation setup and termination are ADDBA Request frame ADDBA Response frame DELBA frame All three frames are action frames […]
Block ACK Frame Formats – Block Ack
To understand the Block ACK Request frame – kindly refer here — <Block ACK Request Frame>. Block Ack Frame The Block Ack frame is shown below The Duration ID is set to the time required to transmit one ACK frame + a SIFS duration The RA field incorporates the address of the recipient station which […]
Regulatory Requirements in 802.11
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 […]
Country Element Subband triplet with operating Extension identifier < 201
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 […]
Country Element Subband triplet with operating Extension identifier > 201
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 […]
Station Operation when entering a new Regulatory domain
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 […]
Dynamic Frequency Selection in WLAN
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 […]
Access Point detection of DFS signal and operation
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 […]
Extended Channel switch announcement and its usage
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 and it’s signatures
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 […]