Weighted Round Robin Scheduling Research Articles

Load Balancing Oriented Predictive Routing Algorithm for Data Center Networks

A data center undertakes increasing background services of various applications, and the data flows transmitted between the nodes in data center networks (DCNs) are consequently increased. At the same time, the traffic of each link in a DCN changes dynamically over time. Flow scheduling algorithms can improve the distribution of data flows among the network links so as to improve the balance of link loads in a DCN. However, most current load balancing works achieve flow scheduling decisions to the current links on the basis of past link flow conditions. This situation impedes the existing link scheduling methods from implementing optimal decisions for scheduling data flows among the network links in a DCN. This paper proposes a predictive link load balance routing algorithm for a DCN based on residual networks (ResNet), i.e., the link load balance route (LLBR) algorithm. The LLBR algorithm predicts the occupancy of the network links in the next duty cycle, according to the ResNet architecture, and then the optimal traffic route is selected according to the predictive network environment. The LLBR algorithm, round-robin scheduling (RRS), and weighted round-robin scheduling (WRRS) are used in the same experimental environment. Experimental results show that compared with the WRRS and RRS, the LLBR algorithm can reduce the transmission time by approximately 50%, reduce the packet loss rate from 0.05% to 0.02%, and improve the bandwidth utilization by 30%.

CDMA-Based Dynamic Power and Bandwidth Allocation (DPBA) Scheme for Multiclass EPON: A Weighted Fair Queuing Approach

Multiclass systems with different quality of service (QoS) requirements are essential in today's Ethernet passive optical networks (EPONs). In this paper, we propose a code division multiple-access-enabled dynamic power and bandwidth allocation (DPBA) algorithm for a multiclass system. The novelty of the proposed algorithm is the resource allocation components: power control and bandwidth allocation. Both resources are related and optimized through the weights of the weighted round-robin scheduler in a way to meet the physical layer signal to interference ratio and the network layer packet delay requirements for every class of users. Our objective is to offer a differentiated class of services for all optical network units while optimizing network performance and guaranteeing fairness between different classes. A closed-form solution for the optimal power and bandwidth allocation using the DPBA algorithm is analytically derived. It is shown that the proposed algorithm can radically enhance the network performance in terms of packet delay, throughput, queue size management, transmission cycle time, and class of service fairness while guaranteeing the QoS requirements for all classes.

Design and dimensioning of an edge router using Markov model

This paper presents the formulation, modelling and analysis of network traffic for the purpose of designing an edge router. Presuming packet arrival in Poisson's process and departure or service time distribution to be exponential, a Markov model has been developed. The stochastic characteristics of the traffic has been monitored and studied over long durations. Traffic data was captured from internet backbone. Different design parameters like buffer capacity, outgoing link speed and various other key parameters have been derived. Additionally, an algorithm has been suggested to manipulate the weights of the queues dynamically in a weighted round robin scheduling, thereby changing the packet departure rate of the flows. The algorithm eventually provides a control over the load factors and the probability of packet drop of the flows as per the need of quality of service and differentiated service.

Queueing Delay Analysis for the Joint Scheduling Exploiting Multiuser Diversity over a Fading Channel

In this paper, we consider a joint packet scheduling algorithm for wireless networks and investigate its characteristics. The joint scheduling algorithm is a combination of the Knopp and Humblet (KH) scheduling, which fully exploits multiuser diversity, and the probabilistic weighted round-robin (WRR) scheduling, which does not use multiuser diversity at all. Under the assumption that the wireless channel process for each user is described by the Nakagami-m model, we develop a formula to estimate the tail distribution of the packet delay for an arbitrary user under the joint scheduling. Numerical results exhibit that under the joint scheduling, the ratio of the number of slots assigned for the WRR scheduling to that for the KH scheduling dominates the characteristics of the delay performance.

Service differentiation in multirate wireless networks with weighted round-robin scheduling and ARQ-based error control

The radio link-level delay statistics in a wireless network using adaptive modulation and coding (AMC), weighted round-robin (WRR) scheduling, and automatic repeat request-based error control is analyzed in this letter. WRR scheduling can be used for service differentiation similar to that achievable by using the generalized processor sharing scheduling discipline. The analytical framework presented in this letter captures physical and radio link-level aspects of a multirate multiuser wireless network (e.g., general fading model, AMC, scheduling, error control) in a unified way. It can be used for admission control and cross-layer design under statistical delay constraints. The analytical results are validated by simulations. Typical numerical results are presented, and their useful implications on the system performance are discussed.

Design and analysis of a class-aware recursive loop scheduler for class-based scheduling

In this paper, we consider the problem of devising a loop scheduler that allocates slots to users according to their relative weights as smoothly as possible. Instead of the existing notion of smoothness based on balancedness, we propose a variance-based metric which is more intuitive and easier to compute. We propose a recursive loop scheduler for a class-based scheduling scenario based on an optimal weighted round-robin scheduler. We show that it achieves very good allocation smoothness with almost no degradation in intra-class fairness. In addition, we also demonstrate the equivalence between our proposed metric and the balancedness-based metric.

Fair weighted round robin scheduling scheme for DiffServ networks

A novel weighted round robin scheduling scheme for differentiated service networks is presented. The weight of each service class can be changed according to the current network conditions. This scheme maintains fairness for all priority service classes. It can be applied in congestion pricing as well as other scenarios.

Latency of weighted round-robin scheduler

The weighted round-robin (WRR) scheduler can be used to provide bandwidth guarantees in asynchronous-transfer-mode networks. Currently, only the formula for the latency of the WRR scheduler with consecutive spreading is available. A formula for the latency of WRR schedulers with arbitrary spreading is presented.

Enhanced weighted round robin schedulers for accurate bandwidth distribution in packet networks

Weighted round robin (WRR) schedulers constitute a popular solution for differentiating the bandwidth guarantees of heterogeneous IP flows, mostly because of their minimal implementation cost. However, the existing WRR schedulers are not sufficient to satisfy all the requirements of emerging quality-of-service frameworks. Flexible bandwidth management at the network nodes requires the deployment of hierarchical scheduling structures, where bandwidth can be allocated not only to individual flows, but also to aggregations of those flows. With currently available WRR schedulers, the superimposition of a hierarchical structure compromises the simplicity of the basic scheduler. WRR schedulers are also known for their burstiness in distributing service, which exposes the scheduled flows to higher packet-loss probability at downstream nodes. By construction, WRR schedulers distribute bandwidth proportionally to the service shares allocated to the individual flows. For best-effort (BE) flows, having no specified bandwidth requirements, existing WRR schedulers typically allocate arbitrary service shares. This approach conflicts with the intrinsic nature of BE flows and reduces the availability of bandwidth for the allocation of guaranteed-bandwidth (GB) flows. We present three enhancements for WRR schedulers that solve these problems. In the first enhancement, we superimpose a “soft” scheduling layer on the basic WRR scheduler by simply redefining the computation of the flow timestamps. The second enhancement substantially reduces the service burstiness of the WRR scheduler with only marginal impact on its implementation cost. Finally, the third enhancement allows the smooth integration of GB and BE flows, with efficient management of the available bandwidth and total compliance with the nature of BE flows.

Bound analysis for WRR scheduling in a statistical multiplexer with bursty sources

Among various cell scheduling schemes for ATM networks, weighted round?robin (WRR) seems a promising algorithm for explicit bandwidth allocation [15]. In this paper, we present a method for analyzing a discrete?time queueing model of a statistical multiplexer with contiguous slot assignments, deterministic vacations, and bursty input sources, which serves as a bound analysis for WRR scheduling in ATM networks. Similar models have been studied as well in the context of TDMA (time division multiple access) schemes with multiple contiguous slots assigned per frame [3,16]. For the model under study, after establishing an expression for the probability generating function (pgf) of the system contents, we derive closed?form expressions for performance measures such as the expected value, and an asymptotic approximation for the tail probabilities of the system contents distribution. Also, after examining the cell delay, we formulate the pgf of the cell delay in a closed form in terms of the system contents pgf. The numerical results obtained for the system contents and cell delay distributions illustrate that they match with simulation results extremely well, especially in the low probability area. We also discuss the impact of the slot assignment cycle of WRR on the system performance.