It seems to me that the use of Access Categories in EDCA is unfair by definition. A user might decide to place all its traffic (even if is P2P file sharing ) in a high priority queue. That user will obtain higher bitrates and lower latency at the expense of the users that place each kind of traffic to the appropriate queue.
Additionally, delayed voice packet might be useless at the receptor. If a packet voice is delayed due to retransmission attempts, it will provoke the delay of the rest of the packets in the queue and could happen that all of them had to be dropped because the delay budget has been exceeded.
My proposal is that if a voice packet suffers a collision, it should be dropped and the contention window for the following packet should be doubled. With my proposal, the high priority queues will obtain higher bit rates and lower delays (thanks to shorter AIFS and smaller contention windows). On the other hand, lower priority queues will obtain higher reliability thanks to the retransmission mechanism.
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1 comment:
Viam:
Correcte: però en principi es pot assumir que tot és fa de manera correcta.
Cert.
Ok. Per tant, simplement fer R=1 (l'EDCA ho permet). Fixa't que fins i tot, hi
ha la ACK policy: NO ACK, que implica que el receptor ni s'envia l'ACK
corresponent, és a dir, tant és si el paquet col·lisiona o té errors. El que no
es fa és incrementar el CWmin... i per experiència, no ho veig necessari.
Boris
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