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/*
* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef MODULES_CONGESTION_CONTROLLER_PCC_UTILITY_FUNCTION_H_
#define MODULES_CONGESTION_CONTROLLER_PCC_UTILITY_FUNCTION_H_
#include "modules/congestion_controller/pcc/monitor_interval.h"
namespace webrtc {
namespace pcc {
// Utility function is used by PCC to transform the performance statistics
// (sending rate, loss rate, packets latency) gathered at one monitor interval
// into a numerical value.
// https://www.usenix.org/conference/nsdi18/presentation/dong
class PccUtilityFunctionInterface {
public:
virtual double Compute(const PccMonitorInterval& monitor_interval) const = 0;
virtual ~PccUtilityFunctionInterface() = default;
};
// Vivace utility function were suggested in the paper "PCC Vivace:
// Online-Learning Congestion Control", Mo Dong et all.
class VivaceUtilityFunction : public PccUtilityFunctionInterface {
public:
VivaceUtilityFunction(double delay_gradient_coefficient,
double loss_coefficient,
double throughput_coefficient,
double throughput_power,
double delay_gradient_threshold,
double delay_gradient_negative_bound);
double Compute(const PccMonitorInterval& monitor_interval) const override;
~VivaceUtilityFunction() override;
private:
const double delay_gradient_coefficient_;
const double loss_coefficient_;
const double throughput_power_;
const double throughput_coefficient_;
const double delay_gradient_threshold_;
const double delay_gradient_negative_bound_;
};
// This utility function were obtained by tuning Vivace utility function.
// The main difference is that gradient of modified utilify funtion (as well as
// rate updates) scales proportionally to the sending rate which leads to
// better performance in case of single sender.
class ModifiedVivaceUtilityFunction : public PccUtilityFunctionInterface {
public:
ModifiedVivaceUtilityFunction(double delay_gradient_coefficient,
double loss_coefficient,
double throughput_coefficient,
double throughput_power,
double delay_gradient_threshold,
double delay_gradient_negative_bound);
double Compute(const PccMonitorInterval& monitor_interval) const override;
~ModifiedVivaceUtilityFunction() override;
private:
const double delay_gradient_coefficient_;
const double loss_coefficient_;
const double throughput_power_;
const double throughput_coefficient_;
const double delay_gradient_threshold_;
const double delay_gradient_negative_bound_;
};
} // namespace pcc
} // namespace webrtc
#endif // MODULES_CONGESTION_CONTROLLER_PCC_UTILITY_FUNCTION_H_
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