TY - JOUR
N2 - In this paper we derive mathematical description of TCP (Transmission Control Protocol) retransmission probability based on Jacobson’s smoothing algorithm that belongs to EWMA (Exponentially Weighted Moving Average) category. This description is parametrized on the probability density function (pdf) of RTT (Round Trip Time) samples and α, β – two primary parameters of Jacobson’s algorithm. Although it is not a close form expression, it is formulated as an effective algorithm that let us to explicitly calculate the values of RTO (Retransmission Time Out) probability as a function of α, β and the pdf of RTT samples. We achieve the effectiveness of this approach by applying smart discretization of the state space and replacement of continuous functions with discrete approximate equivalents. In this way, we mitigate the cardinality of discrete distributions we deal with that results in linear (n+m) instead of multiplicative (n⋅m) growth of computational complexity. We provide the evaluation of RTO probability for a wide set of α, β parameter values and differently shaped Normal and Laplace pdfs the RTT samples are taken from. The obtained numerical results let us to draw some conclusions regarding the choice of optimal values of α, β parameters as well as the impact of pdf the RTT samples are taken from.
L1 - http://journals.pan.pl/Content/130717/31-4414-Janowski-sk-new.pdf
L2 - http://journals.pan.pl/Content/130717
PY - 2024
IS - No 1
EP - 260
DO - 10.24425/ijet.2024.149538
KW - TCP
KW - EWMA
KW - Jacobson’s algorithm
KW - retransmission timeout
KW - retransmission probability
A1 - Grabowski, Michał
A1 - Janowski, Robert
PB - Polish Academy of Sciences Committee of Electronics and Telecommunications
VL - vol. 70
DA - 23.03.2024
T1 - The analytical framework for optimizing TCP retransmission algorithm based on adjustment of its EWMA parameters
SP - 253
UR - http://journals.pan.pl/dlibra/publication/edition/130717
T2 - International Journal of Electronics and Telecommunications
ER -