User Manual, Developers Guide and API Documentation

Backoff.hpp

Go to the documentation of this file.

/******************************************************************************
 * Glue                                                                       *
 * __________________________________________________________________________ *
 *                                                                            *
 * Copyright (C) 2005-2006                                                    *
 * Lehrstuhl fuer Kommunikationsnetze (ComNets)                               *
 * Kopernikusstr. 16, D-52074 Aachen, Germany                                 *
 * phone: ++49-241-80-27910 (phone), fax: ++49-241-80-22242                   *
 * email: wns@comnets.rwth-aachen.de                                          *
 * www: http://wns.comnets.rwth-aachen.de                                     *
 ******************************************************************************/

#ifndef GLUE_MAC_BACKOFF_HPP
#define GLUE_MAC_BACKOFF_HPP

#include <WNS/service/phy/copper/CarrierSensing.hpp>
#include <WNS/Observer.hpp>

#include <WNS/events/MemberFunction.hpp>
#include <WNS/logger/Logger.hpp>
#include <WNS/distribution/Uniform.hpp>
#include <WNS/simulator/Time.hpp>
#include <WNS/events/scheduler/IEvent.hpp>

namespace glue { namespace mac {

    class BackoffObserver
    {
    public:
        virtual
        ~BackoffObserver()
        {}

        virtual void
        backoffExpired() = 0;

        // FIXME: should not be here
        virtual void
        onCarrierIdle()
        {}
    };

    class Backoff :
        public wns::Observer<wns::service::phy::copper::CarrierSensing>
    {
        typedef wns::events::MemberFunction<Backoff> LocalSignal;

    public:
        explicit
        Backoff(
            BackoffObserver* backoffObserver,
            wns::simulator::Time sifsLength,
            wns::simulator::Time slotLength,
            wns::simulator::Time ackLength,
            const wns::logger::Logger& _logger);

        virtual ~Backoff();

        virtual void    transmissionRequest(bool isRetransmission = false);

        virtual void    timerExpired();

        virtual void    onCarrierIdle();

        virtual void    onCarrierBusy();

        virtual void    onCollision();

        virtual bool    isCarrierIdle() const;

    private:
        void startNewBackoffCountdown(wns::simulator::Time ifsLength);

        void waitForTimer(wns::simulator::Time& waitLength);

        enum State {
            idle,
            inSIFS,
            inSlotCountdown,
            finished,
            waitingForCarrierIdle
        };

        enum CarrierSensingResult {
            carrierIdle,
            carrierBusy,
            carrierError
        };

        enum tTransmissionState {
            none,
            pending,
            transmitting
        };

        BackoffObserver* backoffObserver;

        wns::simulator::Time sifsLength;
        wns::simulator::Time slotLength;
        wns::simulator::Time ackLength;
        wns::simulator::Time difsLength;
        wns::simulator::Time eifsLength;

        State state;
        tTransmissionState transmissionState;

        int cwMin;
        int cwMax;
        int cw;
        wns::distribution::Uniform uniform;
        wns::events::scheduler::IEventPtr currentSignal;
        wns::logger::Logger logger;
        CarrierSensingResult carrierSenseResult;

        // For testing purpose this method and variable is protected and may be
        // set by a special version of the backoff
    protected:
        int counter;
        
    };
} // mac
} // glue

#endif // GLUE_MAC_BACKOFF_HPP

---