Wael Hosny Fouad Aly

Using closed loop feedback control theoretic techniques to improve obs networks performance

This paper considers the use of closed loop feedback control theoretic techniques to improve the performance of Optical Burst Switching (OBS) networks. In OBS networks, the Burst Loss Ratio (BLR) is the ratio between the lost bursts to the sent bursts. The BLR is used as a performance metric. The desired burst loss ratio depends on the application using the network. Some applications might tolerate more burst loss ratios than other applications. Higher network link utilization could be achieved by having more control over the burst loss ratio. Burstification rate is the rate of injecting bursts into the OBS network. In this paper, a novel technique to control the burst loss ratio in OBS networks is proposed. The technique is based on classical control theory approaches to tune the burstification rate in order to achieve a desired burst loss ratio to satisfy the application requirements. Extensive experiments show that the proposed technique achieves promising results. That is, the measured burst loss ratio hovers around the desired burst loss ratio and higher utilization is observed. Empirical approaches are used to identify the proposed model. The empirical model fits the OBS network by a value that did not fall below 75%.

Adaptive Offset for OBS networks using Feedback Control Techniques

Optical Burst Switching (OBS) has been developed as an efficient switching technique for the next generation optical Internet. A critical issue in OBS is the burst loss which could occur due to contention and/or insufficient offset time. Burst Loss Ratio (BLR) is used as the main performance parameter in OBS networks. In this paper, we investigate the assignment of the offset time and its effect on the measured end to end (E2E) delay. A novel feedback control technique is proposed to adapt the offset time based on the network condition in terms of BLR. Simulations show that the feedback control is able to adjust the offset automatically and dynamically. Hence, it reduces both the BLR due to insufficient offset and the E2E delay.

Dynamic Adaptation of Policies in Data Center Management

This paper applies the use of control-theoretic techniques and feedback consisting of current system behaviour to implement policies such that threshold values specified in the policies are optimized. The proposed approach in this paper is compared to other dynamic feedback control approaches. Results show that the proposed approach outperforms the other dynamic feedback control approaches. It managed to increase the number of processed requests and reduce the number of violations experienced.

Using feedback control to manage QoS for clusters of servers providing service differentiation

This paper considers the use of feedback to improve the performance of computing systems that offer differentiated services. The motivation of the work is based on the increasing demand on application servers. It is not always sufficient to buy high-performance software for the server. Multiple servers may be needed. To guarantee that QoS requirements are satisfied, it is possible to statically assign resources for a specific class. This often results in underutilization of resources. This paper describes a novel technique that is based on control theory principles applied to a server cluster that provides differentiated service. The paper shows that feedback can be used to adjust the number of client requests concurrently being processed based on dynamic information such as CPU utilization. The paper also compares the use of the proposed technique with a dynamic non control-theoretic approach that is not based on control theory principles. Results show a dramatic increase in the number of served users using the control theory principles compared with a non control-theoretic approach during the same experiment duration. The improvement provided by the proposed technique exceeded 20%.

MNDWSN for Helping People with Different Disabilities

This paper introduces a monitoring and navigation system to help people with disabilities ( MND WSN ). The proposed system is based on wireless sensor networks. In the MND WSN system, each disabled person uses a handheld smart phone device. Three types of disabilities are studied in this paper: (1) blind, (2) deaf, and (3) on wheelchair. We experimented with a three-floor university building. Sensor nodes and cameras are scattered in all rooms and hallways. Smart phones are used to communicate with the sensor nodes to take instructions to navigate through the appropriate path. Dijkstras algorithm is used for navigation. MND WSN also monitors the disabled person while navigating. The proposed system is compared to a baseline reference experiment. Results show improvement of 34% compared to the baseline reference experiment.

TCP Based Estimation Method for Loss Control in OBS Networks

Optical Burst Switching (OBS) has been developed as an efficient switching technique for the next generation optical Internet. A critical issue for OBS networks is the burst loss which could occur due to contention and/or insufficient offset time. Burst Loss Ratio (BLR) is used as the main performance parameter in bufferless OBS networks. This paper proposes a new TCP statistics based method to predict the BLR without using any feedback information from the network. The idea is to estimate the BLR based on the TCP statistics available at the edge node. Our proposed BLR prediction method is then integrated into the closed loop feedback control model [1-3] to control the BLR inside the network. Our simulation results clearly show that our proposed method improves the efficiency of the closed loop feedback control model while avoiding the use of any feedback information from the network.

On controlling burst loss ratio inside an OBS network

This paper considers the use of closed loop feedback control theoretic techniques to improve the performance of optical burst switching (OBS) networks. In OBS networks, the burst loss ratio (BLR) is the ratio between the lost bursts to the sent bursts. The BLR is used as a performance metric. The desired burst loss ratio depends on the application using the network. Burstification rate is the rate of injecting bursts into the OBS network. In this paper, a novel technique to control the burst loss ratio in OBS networks is proposed. The technique is based on classical control theory approaches to tune the burstification rate in order to achieve a desired burst loss ratio to satisfy the application requirements. Extensive simulations on the NSFNET topology show that the proposed technique achieves promising results. That is, the measured burst loss ratio hovers around the desired burst loss ratio for all nodes.

Feedback Control Theoretic Technique for Data Centers

One challenge associated with developing autonomic systems is that the system has multiple elements that should be autonomic but must also interoperate with each other. This paper addresses this problem within the context of dynamic resource allocation within a data center based on control-theoretic techniques.

On providing QoS in optical burst switched networks using feedback control

This paper proposes a novel scheme that uses feedback control approaches to support quality of service (QoS) in Optical Burst Switching (OBS) networks. This work provides service level objectives in terms of burst loss ratio (BLR) for each class of bursts. The BLR is the ratio between the lost bursts to the sent bursts. Using feedback control approaches computes accurate burstification rate for each class of bursts. Burstification rates are computed at each burst manager controller for each class based on the previous measured value of the burst loss rate and the desired burst loss rate. Simulation results on NSFNET network have showed that the feedback control scheme guarantees a BLR to hover around the desired value for each class of bursts.

Adaptive Hybrid Deflection and Retransmission Routing for Optical Burst-Switched Networks

Burst contention is a well known challenging problem in Optical Burst Switching (OBS) networks. Deflection routing is used to resolve contention. Burst retransmission is used to reduce the Burst Loss Ratio (BLR) by retransmitting dropped bursts. Previous works show that combining deflection and retransmission outperforms both pure deflection and pure retransmission approaches. This paper proposes a new Adaptive Hybrid Deflection and Retransmission (AHDR) approach that dynamically combines deflection and retransmission approaches based on network conditions such as BLR and link utilization. Network Simulator 2 (ns-2) is used to simulate the proposed approach on different network topologies. Simulation results show that the proposed approach outperforms static approaches in terms of BLR and goodput.