The fundamental light-dependent effect, i.e., a large but slow threshold-voltage shift based on charge trapping in the aluminum oxide of the gate dielectric or at the semiconductor dielectric interface, is analyzed depending on various parameters, such as biasing conditions, integration time, wavelength and power of the incoming light as well as the channel length.
It also updates slow start threshold by tracking stable window.
When the congestion window reaches the Slow Start Threshold, the Congestion Avoidance phase starts.
In addition, the slow start threshold is modified to be updated by tracking stable window.
When cwnd reaches the slow start threshold (ssthresh), the TCP source enters the congestion avoidance phase and the cwnd increases linearly by round trip times (RTTs).
Based on the authors study, this problem stems from the large minimum congestion window of Vegas, large reset slow start threshold and aggressive window increase policy.
This approach has been proposed to overcome the problems of the large minimum congestion window, large reset slow start threshold and aggressive window increase policy of TCP-Vegas in multi-hop wireless networks.
Otherwise, if θ < 1, TDACKs are considered caused by a congestion, and fast recovery action is performed, by halving the congestion window and setting the slow start threshold to this new value.
On the other hand, if duplicated ACKs are received with CW mark, sender will enter the rate control procedure to adjust its slow start threshold and congestion window size to the latest optimum congestion window size.
When a loss occurs, either by receiving three duplicated ACKs or after a time-out, TCP-Westwood uses the estimated bandwidth to capture the congestion state much faster and then computes the congestion window and slow start threshold.
