diff --git a/src/wifi/doc/source/wifi-design.rst b/src/wifi/doc/source/wifi-design.rst index 8967d290b..745f1f7e2 100644 --- a/src/wifi/doc/source/wifi-design.rst +++ b/src/wifi/doc/source/wifi-design.rst @@ -1058,6 +1058,52 @@ optionally (depending on the value of the ``EnableBsrp`` attribute) precede the of a Basic Trigger Frame in order for the AP to collect information about the buffer status of the stations. +Enhanced multi-link single radio operation (EMLSR) +################################################## + +The IEEE 802.11be amendment introduced EMLSR operating mode to allow a non-AP MLD to alternate +frame exchanges over a subset of setup links identified as EMLSR links. |ns3| supports EMLSR +operations as described in the following. + +Non-AP MLD side +--------------- + +A non-AP MLD supports EMLSR operating mode if the ``EmlsrActivated`` attribute of the EHT +configuration is set to true. In such a case, the WifiMacHelper will install an EMLSR Manager +by using the type and attribute values configured through the ``SetEmlsrManager`` method. The +EMLSR Manager is a base class providing the ``EmlsrLinkSet`` attribute, which can be used to +enable or disable EMLSR mode (after multi-link setup, EMLSR mode is disabled by default). Setting +the ``EmlsrLinkSet`` attribute triggers the transmission of an EML Operating Mode Notification +frame to the AP to communicate the new set of EMLSR links, if ML setup has been completed. +Otherwise, the set of EMLSR links is stored and the EML Operating Mode Notification frame is +sent as soon as the ML setup is completed. The selection of the link used to transmit +the EML Operating Mode Notification frame is done by the EMLSR Manager subclass. The default +EMLSR Manager subclass, ``DefaultEmlsrManager``, selects the link that was used to perform +ML setup. When the non-AP MLD receives the acknowledgment for the EML Operating Mode Notification +frame, it starts a timer whose duration is the transition timeout advertised by the AP MLD. +When the timer expires, or the non-AP MLD receives an EML Operating Mode Notification frame +from the AP MLD, the EMLSR mode is assumed to be enabled (or disabled). + +AP MLD side +----------- +An AP MLD supports EMLSR operating mode if the ``EmlsrActivated`` attribute of the EHT +configuration is set to true. When an AP MLD that supports EMLSR operating mode has to initiate a +frame exchange with a non-AP MLD that is operating in EMLSR mode, it sends an MU-RTS Trigger Frame +soliciting a response from the non-AP MLD (and possibly others) as the initial Control frame for +that exchange. The MU-RTS Trigger Frame includes a Padding field whose transmission duration is the +maximum among the padding delays advertised by all the EMLSR clients solicited by the MU-RTS +Trigger Frame. Also, the MU-RTS Trigger Frame is carried in a non-HT (duplicate) PPDU transmitted +at a rate of 6 Mbps, 12 Mbps or 24 Mbps. When the transmission of an initial Control frame starts, +the AP MLD blocks transmissions to the solicited EMLSR clients on the EMLSR links other than the +link used to transmit the initial Control frame, so that the AP MLD does not initiate another +frame exchange on such links. The frame exchange with an EMLSR client is assumed to terminate +when the AP MLD does not start a frame transmission a SIFS after the response to the last frame +transmitted by the AP MLD or the AP MLD transmits a frame that is not addressed to the EMLSR +client. When a frame exchange with an EMLSR client terminates, the AP MLD blocks transmissions on +all the EMLSR links and starts a timer whose duration is the transition delay advertised by the +EMLSR client. When the timer expires, the EMLSR client is assumed to be back to the listening +operations and transmissions on all the EMLSR links are unblocked. + Ack manager ###########