Chen's Learning Note

  A WLAN sensing procedure uses two sets of roles: •  Sensing initiator and sensing responder : to discriminate  between the STA, called sensing initiator, that initiates the  WLAN sensing procedure (i.e., the STA that supports a  sensing application), and the STA, called sensing responder,  that participates in the procedure by responding to  the sensing initiator. •  Sensing transmitter and sensing receiver : to discriminate  between a STA, called sensing transmitter, that transmits  PPDUs to allow for sensing measurements and a STA,  called sensing receiver, that receives PPDUs sent by the  sensing transmitter to perform sensing measurement. Below figure summarizes the possible role combinations and associated  message exchanges.  We can  first observe that the sensing measurements are obtained with  the transmission of NDPs. And then, the  sensing report can only be sent by a sensing responder actin...

Sensing systems can be categorized based on the number of devices used to obtain sensing measurements.  These  architectures are naturally supported by Wi-Fi systems: • Monostatic requires only one station (STA) and at least  two antennas. This architecture does not need any communication  or coordination between multiple STAs from  a sensing point-of-view and therefore does not need to  be specifically addressed by a Wi-Fi sensing standard as  long as it respects IEEE 802.11 mandatory requirements  (e.g., channel access). • Bistatic requires a communication between two STAs. It  can thus be achieved between an AP and a client (a client  being typically connected to a single AP). • Multistatic requires communication involving more than  two STAs and can thus be achieved between an AP and  multiple clients either by obtaining measurements using  signals transmitted by multiple clients or by transmitting  signals that a...

1. Install JRE to the Linux OS :     sudo apt-get install default-jre 2. Upgrade to the JAVA 1.8 :    sudo add-apt-repository ppa:webupd8team/java    sudo apt-get update    sudo apt-get install oracle-java8-installer

With fragmentation the MSDU would be broken into smaller sections and each section encapsulated in an MPDU . Each MPDU is sent in a separate PPDU with the preamble of each PPDU providing a new  channel estimate. (PHY Layer) MSDU fragmented condition:  when its length exceeds a threshold . Each fragment contains an even number of bytes and all fragments are the same size , except the last fragment, which may be smaller. The timing relation between A-MSDU/A-MPDU/PPDU :

1.What is Short Inter-frame Space (SIFS)? Ans : the small time interval between the data frame and its acknowledgment . Used for the highest priority transmissions enabling stations with this type of information to access the radio link first. 2. What is the content of SIFS ? Ans :This value is fixed per PHY and is calculated in such a way that transmitting station will be able to switch back to receive mode and be capable of decoding the incoming packets. A SIFS duration is a constant value and it depends on the amendments . 3.What is  DCF inter-frame space( DIFS) ? Ans : The DIFS is used by stations operating under the DCF method to transmit data frames and management.(Read more : DCF Method ) 4.How to use DIFS? Ans : A station using the DCF is allowed to transmit if it determines that the medium is idle for the duration of the DIFS, or if it determines that the medium is idle for the duration of the DIFS + the remaining back-off time following the recept...

The random back-off count is selected as a pseudo-random integer drawn from a uniform distribution over the interval [0,CW] , where CW, an integer value, is the contention window. Update procedure of CW value 1. CW parameter takes the initial value CWmin . 2. Every unsuccessful MPDU transmit , for example each time an ACK response is not received for a data frame. CW parameter doubles . 3. Every successful MPDU transmit, CW parameter reset . 4. If CW parameter increase due to unsuccessful MPDU transmit and reach the value CWmax , CW parameter keep CWmax until reset . Random back-off procedure 1. As shown in the figure above, STA3 which select the smallest back-off count win the contention and transmit first. 2. STA2 and STA4  suspend their back-off and resume DIFS after the medium goes to idle . 3. STA4, which select the second smallest back-off count win the 2nd contention. 4. And it goes STA2 and finally STA1 transmit.