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wifi: Add sphinx documentation for EMLSR operations

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Stefano Avallone
2023-03-22 14:50:40 +01:00
committed by Stefano Avallone
parent 7c81899fe1
commit af947e7d62
1 changed files with 46 additions and 0 deletions
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src/wifi/doc/source/wifi-design.rst
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@@ -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
###########