One-way Delay Estimation Research Articles

A Round Trip Time Weighting Model for One-Way Delay Estimation

A Round Trip Time Weighting Model for One-Way Delay Estimation

Accurate One-Way Delay Estimation With Reduced Client Trustworthiness

The requirement for accurate one-way delay (OWD) estimation led to the recent introduction of an algorithm enabling a server to estimate OWDs between itself and a client by cooperating with two other servers, requiring neither client-clock synchronization nor client trustworthiness in reporting one-way delays. We evaluate the algorithm by deriving the probability distribution of its absolute error and compare its accuracy with the well-known round-trip halving algorithm. While neither algorithm requires client trustworthiness nor client-clock synchronization, the analysis shows that the new algorithm is more accurate in many situations.

Accurate One-Way Delay Estimation: Limitations and Improvements

The one-way delay (OWD) is a crucial parameter in interactive multimedia communications to assess the end users' perception of quality. Precise OWD measurement is a challenge in asymmetric networks in which endpoints are not coordinated and usually without clock synchronization. A usual method estimates the OWD for two endpoints of a connection as equal to one half of the round-trip time, which is not always accurate in the Internet. Employing a third-party node to increase the number of independent equations helps a least-square-error method to estimate the OWD more accurately. Furthermore, adding a couple of constraints to the variables (i.e., OWDs between three nodes) leads to even more precise results. This paper examines the effect of different types of constraints on the accuracy of the cyclic-path method to improve the OWD estimation. To measure the transmission delay, which has a crucial role in the OWD estimation improvement, a simple accurate method is introduced.

Hybrid one-way delay estimation for networked control system

One-way delay estimation in the forward and feedback channels is crucial for a networked control system (NCS) due to its important role in the reliability and availability design. Problems existing in current one-way delay estimation schemes are investigated in this paper. A novel hybrid one-way delay estimation scheme, utilizing the hybrid technique that contains an online monitoring mechanism and an end-to-end estimation method, is proposed to overcome the effects of network asymmetry and delay dynamics in the NCS. Therefore, accurate one-way delay values in the forward and feedback channels can be obtained. In the proposed scheme, only the delay value of the initial packet starting the control loop of the NCS is estimated by the online monitoring mechanism, all the other estimations are performed by the host using the end-to-end method. The experimental results demonstrate that the performance of the proposed novel hybrid one-way delay estimation scheme is better than the other current estimation schemes for the NCS in terms of its high accuracy in tracking delay values as well as requiring lower computation complexity of the system.

One-Way Delay Measurement: State of the Art

Nowadays, the evaluation of performance measurement in computer networks is an important issue. To ensure the quality of service of the network communication, one of the most important network performance parameters is the one-way delay (OWD). For accurate OWD estimation, it is essential to consider some parameters that can influence the measure, such as the operating system and, in particular, the threads, which are concurrent with the measurement application. Moreover, OWD estimation is not an easy task, because it can be affected by synchronization uncertainties. This paper aims to review the different solutions proposed in the scientific literature for OWD measurement. These solutions adopt different methods to guarantee a reasonable clock synchronization based on the Network Time Protocol, the Global Positioning System, and the IEEE 1588 Standard. These different approaches are critically reviewed, showing their advantages and disadvantages.

One-way delay estimation using network-wide measurements

We present a novel approach for the estimation of one-way delays between network nodes without any time synchronization in the network. It is based on conducting multiple and simple one-way measure...

One-way delay estimation using network-wide measurements

We present a novel approach for the estimation of one-way delays between network nodes without any time synchronization in the network. It is based on conducting multiple and simple one-way measurements among pairs of nodes, and estimating the one-way delays by optimizing the value of a global objective function that is affected by the overall network topology and not just by individual measurements. We examine two objective functions. The first intuitive choice is the least square error (LSE). Using a novel concept of delay-induced link probabilities, we develop a second objective function that is based on the maximum-entropy (ME) principle. Extensive numerical experiments show that both functions considerably outperform the common method of halving the round-trip delays. They also show that ME outperforms the commonly used LSE.

One-way delay estimation and its application

Delay estimation is a difficult problem in computer networks. Accurate one-way delay estimation is crucial because it serves a very important role in network performance and thus application design. RTT (Round Trip Time) is often used as an approximation of the delay, but because it is a sum of the forward and reverse delays, the actual one-way delay cannot be estimated accurately from RTT. To estimate one-way delay accurately, this paper proposes a new scheme that analytically derives one-way delay, forward and reverse delay, respectively. We show that the performance of TCP can improve dramatically in asymmetric networks using our scheme. A key contribution of this paper is that our one-way delay estimation is much more accurate than RTT estimation so that TCP can quickly find the network capacity in the slow start phase. Since RTT is the sum of the forward and reverse delays, our scheme can be applied to any protocol that is based on RTT.

Analytical derivation of one-way delay

Delay estimation is a difficult problem in computer networks. Round trip time (RTT) is often used as an approximation of the delay but, because it is a sum of the forward and reverse delays, the actual one-way delay cannot be estimated accurately from RTT. Accurate one-way delay estimation becomes crucial because it serves a very important role in network and application design. A new scheme is proposed for estimating one-way delay. One-way delay, and forward and reverse delay are analytically derived.