During the stage of listening, all nodes try to get access to the channel and in this situation, when network traffic flow is large or in a dense WSNs environment, the conflict between the nodes will exacerbate, which will lead to multiple nodes retransmission back-off, and more energy waste.
In section 4, flow-adaptive back-off algorithm is proposed.
It means that both protocols use a kind of back-off algorithm to postpone node to access the channel.
If the channel is busy, the station must delay its transmission by choosing a random number called back-off in an interval called contention window; this will determine an additional waiting time in order to solve partially channel access conflicts.
The objective of this work is to minimize wait times which lead to under usage of the channel by combining IFS and back-off times.
DCF follows the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol with Binary Exponential Back-off algorithm (BEB).
The back-off counter is suspended when detecting busy medium, and resumed after sensing an idle medium for the duration of DIFS interval.
To analyze and compute the IEEE 802.11 DCF saturated throughput, a Markov chain model for the binary exponential back-off procedure is considered in , and in [11, 12] the authors attempted to construct a mathematical model for the throughput performance of 802.11e, even though they did not present the latency and jitter analysis of a packet.
The model relies on two discrete time processes, to model the progress of a given station through back-off. One process b(t) represents the back-off counter of the station, which is decremented at the end of every idle back-off slot.
In a blunt back-off
message to Westminster, he said: "There are no plans to change the Scotland Act.