Accurate OD Traffic Matrix Estimation Based on Resampling of Observed Flow Data

It is important to observe the statistical characteristics of global flows, which are defined as series of packets between networks, for the management and operation of the Internet. However, because the Internet is a diverse and large-scale system organized by multiple distributed authorities, it is not practical (sometimes impossible) to directly measure the precise statistical characteristics of global flows. In this paper, we consider the problem of estimating the traffic rate of every unobservable global flow between corresponding origin-destination (OD) pair (hereafter referred to as “individual-flows”) based on the measured data of aggregated traffic rates of individual flows (hereafter referred to as “aggregated-flows”), which can be easily measured at certain links (e.g., router interfaces) in a network. In order to solve the OD traffic matrix estimation problem, the prior method uses an inverse function mapping from the probability distributions of the traffic rate of aggregated-flows to those of individual-flows. However, because this inverse function method is executed recursively, the accuracy of estimation is heavily affected by the initial values of recursion and variation of the measurement data. In order to solve this issue and improve estimation accuracy, we propose a method based on a resampling of measurement data to obtain a set of solution candidates for OD traffic matrix estimation. The results of performance evaluations using a real traffic trace demonstrate that the proposed method achieves better estimation accuracy than the prior method.Asia-Pacific Signal and Information Processing Association Annual Summit and Conference 2018 (APSIPA ASC 2018), 12-15 November 2018, Honolulu, Hawaii, US

TCP Flow Level Performance Evaluation on Error Rate Aware Scheduling Algorithms in Evolved UTRA and UTRAN Networks

We present a TCP flow level performance evaluation on error rate aware scheduling algorithms in Evolved UTRA and UTRAN networks. With the introduction of the error rate, which is the probability of transmission failure under a given wireless condition and the instantaneous transmission rate, the transmission efficiency can be improved without sacrificing the balance between system performance and user fairness. The performance comparison with and without error rate awareness is carried out dependant on various TCP traffic models, user channel conditions, schedulers with different fairness constraints, and automatic repeat request (ARQ) types. The results indicate that error rate awareness can make the resource allocation more reasonable and effectively improve the system and individual performance, especially for poor channel condition users

Unsupervised Ensemble Anomaly Detection Using Time-Periodic Packet Sampling

We propose an anomaly detection method for finding patterns in network traffic that do not conform to legitimate (i.e., normal) behavior. The proposed method trains a baseline model describing the normal behavior of network traffic without using manually labeled traffic data. The trained baseline model is used as the basis for comparison with the audit network traffic. This anomaly detection works in an unsupervised manner through the use of time-periodic packet sampling, which is used in a manner that differs from its intended purpose — the lossy nature of packet sampling is used to extract normal packets from the unlabeled original traffic data. Evaluation using actual traffic traces showed that the proposed method has false positive and false negative rates in the detection of anomalies regarding TCP SYN packets comparable to those of a conventional method that uses manually labeled traffic data to train the baseline model. Performance variation due to the probabilistic nature of sampled traffic data is mitigated by using ensemble anomaly detection that collectively exploits multiple baseline models in parallel. Alarm sensitivity is adjusted for the intended use by using maximum- and minimum-based anomaly detection that effectively take advantage of the performance variations among the multiple baseline models. Testing using actual traffic traces showed that the proposed anomaly detection method performs as well as one using manually labeled traffic data and better than one using randomly sampled (unlabeled) traffic data

Dynamic and Decentralized Storage Load Balancing with Analogy to Thermal Diffusion for P2P File Sharing

In this paper we propose a file replication scheme inspired by a thermal diffusion phenomenon for storage load balancing in unstructured peer-to-peer (P2P) file sharing networks. The proposed scheme is designed such that the storage utilization ratios of peers will be uniform, in the same way that the temperature in a field becomes uniform in a thermal diffusion phenomenon. The proposed scheme creates replicas of files in peers probabilistically, where the probability is controlled by using parameters that can be used to find the trade-off between storage load balancing and search performance in unstructured P2P file sharing networks. First, we show through theoretical analysis that the statistical behavior of the storage load balancing controlled by the proposed scheme has an analogy with the thermal diffusion phenomenon. We then show through simulation that the proposed scheme not only has superior performance with respect to balancing the storage load among peers (the primary objective of the present proposal) but also allows the performance trade-off to be widely found. Finally, we qualitatively discuss a guideline for setting the parameter values in order to widely find the performance trade-off from the simulation results

部分強化における強化子出現の規則性と反応の持続性― シミュレーション実験による消去抵抗の比較検討―

研究の目的　強化スケジュールにおける強化子出現の規則性とオペラント反応の持続性の関係を消去抵抗を指標として、コンピュータ上のシミュレーション実験によって検討した。研究計画　コンピュータ上の仮想実験でラットのレバー押しを部分強化（VR、FR、VI、FI）か連続強化（CRF）で条件づけし、強化子出現の規則性の違いと消去時の反応の持続性の関係を比較した。場面　オペラント条件づけのシミュレーション実験ソフトを用いて、仮想ラットのレバー押し反応と消去抵抗を測定した。被験体　仮想ラットを5匹ずつ5群に配置した。独立変数の操作　変率強化（VR）、定率強化（FR）、変時隔強化（VI）、定時隔強化（FI）、連続強化（CRF）の強化スケジュールを用いた。行動の指標　消去基準に達するまでのレバー押し反応数、所要時間、反応間時間（IRT）を測定した。結果　消去期の反応数と消去に至るまでの所要時間の違いが確認された。消去1日目には、短いIRTがVR群とFR群に多く、VI群には長いIRTが多いという特徴が確認されたが、消去2日目以降はどの群のIRT分布もCRF群に類似したパターンへと変化していった。結論　強化子出現が不規則で強化期から消去期への条件変化が明瞭でない変動型スケジュールは、その変化が明瞭な固定型もしくは連続強化スケジュールよりも消去抵抗を高めることが確認された