We have seen in a previous article that BSS Color is used in identifying the BSS a 802.11 packet receiving station is connected to. Spatial reuse operation is a method to use the BSS color for inter-BSS Packet detection and to adapt the station to function better in dense deployment conditions suffering from co-channel interference. […]

A non-AP 802.11ax station will maintain 2 NAVs. An 802.11ax Access Point may maintain 2 NAVs. The two NAVs are defined as below: Maintaining two separate NAVs help in the following manner Only when both NAVs are Zero is the Virtual CS indication for the station is that the medium is idle. Else, the medium […]

The 802.11ax standard defines a PPDU as Inter-BSS or Intra-BSS as defined below: If the above conditions are not met for a frame, the frame is characterized as an Intra/Inter-BSS PPDU Dual NAV operation

802.11 stations follow Carrier sense-Multiple Access and Collision Avoidance (CSMA/CA) and the signal detect is around 4 dB above noise floor. Since, the Signal is detected at such a low level, an 802.11 station can latch on to a very far away signal from another BSS (termed Overlapping BSS) and backoff from performing its own […]

The Uplink transmission of frames from 802.11ax capable Stations to an 802.11ax Access Point requires a Trigger frame to be sent by the Access Point to the stations who would participate in the Multi-User UpLink transmission. The Trigger Frame will assign RUs, determine TX power for transmission and spatial streams to the HE capable stations. […]

The Access Point operating in 802.11ax can use the Resource Units that were discussed in the previous article <Resource Units in 802.11ax> to setup packet send to multiple non-AP stations in a single transmission. The Access Point assigns specific Resource Units to Specific stations. The AP encodes a packet meant for a specific station to […]

We saw how Unsolicited BSR is handled in 802.11ax <Buffer Status Reports – Unsolicited BSR>. A Solicited BSR is a response for a request for Buffer Status from a non-AP Station responding to a Buffer Status Report Poll (BSRP) trigger frame from an Access Point. The Trigger frame will have the type set to BSRP […]

Buffer status reports are non-AP stations sending a report to the AP on “Amount of buffered data at station“. This helps the Access Point to determine the RU allocation for specific station. The non-AP station can send buffered data implicitly via QoS control field or BSR control sub-field of any frame transmitted to the Access […]

The MU-RTS frame is a Trigger Frame in 802.11ax which has a trigger sub-field type value of 3. The MU-RTS frame purpose is to elicit a CTS response from atleast one of MU capable Stations addressed in the MU-RTS frame. The Trigger Frame format remains the same for MU-RTS. However, Most of the common info […]

The Trigger frame format and the need for the Trigger Frame was discussed briefly in the article <Trigger Frames in 802.11ax>. The Basic Trigger frame has the same frame format as defined in the previous article. It is depicted below: One major exception is that the “Trigger Dependent Common Info Field” in the Common Information […]