Patent ID: 10165597

Abstract:
In wireless communication networks with distributed medium access control, maximal network throughput is achieved as a compromise between medium contention duration and collision rate. Maximal throughput in self-adapting medium access protocol is achieved by stations maintaining backoff counter BC and freezing counter FC, which define the state in two-dimensional state space. Countdown process is comprised of decrementing BC in idle timeslots, and incrementing FC in busy timeslots. Countdown ends if the value of BC reaches zero, when the station starts to transmit data, or when FC is incremented to be greater than freezing limit FL. In both cases, the station has to randomly select new backoff counter, reset its freezing counter, and continue to count down with these new values of BC and FC. At the end of countdown, the station calculates contention measure CM=a*BC+b*FC, and based on set of CM thresholds CMi, activates one of available contention windows Wi that define the interval of available values for the random selection of new backoff counter [Wimin, Wimax]. In loaded network, the station can increase the total amount of backoff time to be greater than the maximal upper limit of available contention windows by selecting new backoff counter multiple times, which is made possible by limiting countdown freezing. This manifests the self-adaptive nature of the described medium access control protocol. The self-adaptive nature is also manifested in selection of contention window based on contention measure of the previous countdown, which additionally regulates medium contention duration, achieving good network throughput in various network load scenarios.