Access during an MCCAOP by mesh STAs that are not the MCCAOP owner Month Year doc.: IEEE 802.11-yy/xxxxr0 Access during an MCCAOP by mesh STAs that are not the MCCAOP owner Date: November 10, 2010 Authors: Alexander Safonov, IITP RAS Alexander Safonov, IITP RAS

Month Year doc.: IEEE 802.11-yy/xxxxr0 Abstract According to the draft 7.02, an MCCA enabled mesh STA shall not initiate its transmissions within MCCAOPs owned by other STAs But the STA can easily initiate its transmission before the MCCAOP, no matter how much time left before the MCCAOP beginning This rule causes a problem: however MCCA enabled mesh STAs declare that they respect MCCAOPs owned by other STAs, it fact they do not, as their EDCA TXOPs still may overlap with MCCAOPs owned by others The value of MCCA diminishes because of this problem The problem can be solved by adding one more paragraph to the draft, which is proposed in this submission Alexander Safonov, IITP RAS Alexander Safonov, IITP RAS

Problem Statement Although MCCA capable mesh STAs are not allowed to start their transmissions within MCCAOPs owned by others, they are allowed to start transmissions shortly before the MCCAOPs. So, MCCAOP and EDCA TXOPs may overlap This may lead to: 1)MCCA TXOP truncation or 2) collisions, in case of hidden stations Alexander Safonov, IITP RAS

Possible solution 1 Just before its packet transmission, a station checks whether it has enough time to send this packet before the next MCCAOP i.e. the station checks the inequality: TDATA+TSIFS+TACK < tMCCA - current_time where tMCCA is the MCCAOP start time If OK, the STA starts its transmission If NOT OK, the STA defers its transmission and starts new round of the backoff procedure after the MCCAOP is finished Alexander Safonov, IITP RAS

Possible solution 2 Just before its packet transmission, a station checks whether it has enough time to send this packet before the next MCCAOP i.e. the station checks the inequality: TDATA+TSIFS+TACK < tMCCA - current_time where tMCCA is the MCCAOP start time If OK, the STA starts its transmission If NOT OK, the STA defers its transmission and starts new round of the backoff procedure immediately Alexander Safonov, IITP RAS

Possible normative text covering both solution 1 and solution 2 Add the following text after the first sentence of the second paragraph of clause 9.9a.3.11.2 in IEEE 802.11s_D7.02 “When a MCCA enabled mesh STA obtains an EDCA TXOP, the STA shall not start its transmission if the TXOP cannot be finished before the start of an MCCAOP corresponding to a reservation in its neighborhood MCCAOP times. Instead, the STA shall defer the transmission and initiate another backoff procedure with the same value of CW.” Alexander Safonov, IITP RAS

Strawpoll Should the normative text in the previous slide be considered for inclusion in the current draft? Yes: No: Abstain: Alexander Safonov, IITP RAS

Acknowledgement The proposal was made in the framework of ICT FP7 project FLAVIA Alexander Safonov, IITP RAS