The dynamics of responsiveness and smoothness in heterogeneous networks

Abstract

Abstract-Additive increase/multiplicative decrease-based protocols, including transmission control protocol (TCP), TCP-friendly, and a new generation of rate-based protocols, attempt to control the tradeoff of responsiveness and smoothness. Traditionally, smoothness has not been a main concern since it does not impact the performance of regular Internet applications such as the Web, FTP, or e-mail. However, multimedia-driven protocols attempt to favor smoothness at the cost of responsiveness. In general, smoothness and responsiveness constitute a tradeoff; however, we uncover undesirable dynamics of the protocols in the context of wireless/mobile networks with high-error rate or frequent handoffs: low responsiveness is not counterbalanced by gains in smoothness, but instead, produces a conservative behavior that degrades protocol performance with both delay-tolerant and -sensitive applications. Based on our observations, as well as on further analysis of the impact of the bottleneck queue on channel utilization, we seek an alternative strategy for smooth window adjustments. We introduce a new parameter , which implements a congestion avoidance tactic and reaches better smoothness without damaging responsiveness.

Enhancement of TCP over wired/wireless networks with packet loss classifiers inferred by supervised learning

“…TCPWestwood [38] and TCP-Veno [19]). Another example is proposed in [37] where the dynamics of TCP in the context of wireless/mobile networks is studied, with the goal of improving smoothness without damaging responsiveness.…”

A study of deploying smooth‐ and responsive‐TCPs with different queue management schemes

“…cwnd cliff = (RTT 0 +max qdelay)·bw (10) TCP senders then multiplicatively decrease their congestion window, after packet losses due to buffer overflow are detected. Equation (9) demonstrates that increasing cwnd beyond the knee does not enhance further the system throughput, but only results in increasing queuing delay.…”

Taxonomy and Evaluation of TCP-Friendly Congestion-Control Schemes on Fairness, Aggressiveness, and Responsiveness

“…Additionally, this study focuses on inter-fairness, that is, whether a scheme shares the same bandwidth with TCP. Intra-fairness, that is, the fairness among the flows controlled by the same scheme, is discussed in [12,20]. Moreover, the schemes selected herein detect congestion only by packet losses as TCP Reno and SACK [17] do.…”

“…For example, this study uses a common topology -dumbbell -to investigate the TCP-equal share of the schemes but changes the RTT heterogeneity to display the difference between WB and RB schemes. Tsaoussidis et al considered the RTT-heterogeneity in [12] but for the intrafairness of GAIMD flows. Moreover, this study, like [8], uses the oscillating CBR traffic but includes four extra schemes to show three interesting results; that is, SIMD has the fastest aggressiveness, AIAD/H and TFRCP are the most unstable, and TEAR has the slowest aggressiveness.…”

“…Unlike Bansal et al [8], who compare the transient behaviors of various schemes, this study additionally investigates these schemes under the steady state to reveal that they may use bandwidth unequal to TCP even in this case. In addition, this study investigates the bandwidth sharing between TCP and TCP-friendly flows (inter-fairness), differing from Tsaoussidis et al [12], who study the bandwidth sharing among a group of homogeneous flows (intra-fairness).…”