Usage Parameter Control Research Articles

A fuzzy approach to active usage parameter control in IEEE 802.11b wireless networks

Abstract: Usage parameter control (UPC) provides support for quality of service across heterogeneous networks. For the network operator UPC assists in limiting network usage through traffic shaping, to prevent unacceptable delay. Traditional methods to apply UPC involve the generic cell rate algorithm or ‘leaky bucket’ algorithm, now commonly implemented in asynchronous transmission mode networks. This paper proposes a novel form of UPC for 802.11b wireless networks. The method proposed measures the rate of individual network flows to actively manage link utilization using a fuzzy logic controller (FLC). The FLC monitors the flow rate and adjusts the sending transmissions to stabilize flows as close to the optimum desired rate as possible. Imposing UPC and using the FLC within a packet switched TCP network enforces cooperation between competing streams of traffic. After carrying out experiments within a wireless network, the results obtained significantly improve upon a ‘best effort’ service.

Intelligent Leaky Bucket Algorithms for Sustainable-Cell-Rate Usage Parameter Control in ATM Networks

In this paper, we propose two intelligent leaky bucket algorithms for sustainable-cell-rate usage parameter control of multimedia transmission in asynchronous transfer mode networks. One is the fuzzy leaky bucket algorithm, in which a fuzzy increment controller (FIC) is incorporated with the conventional leaky bucket algorithm; the other is the neural fuzzy leaky bucket algorithm, where a neural fuzzy increment controller (NFIC) is added with the conventional leaky bucket algorithm. Both the FIC and the NFIC properly choose the long-term mean cell rate and the short-term mean cell rate as input variables to intelligently determine the increment value. Simulation results show that both intelligent leaky bucket algorithms have significantly outperformed the conventional leaky bucket algorithm, by responding about 160% faster when taking control actions against a nonconforming connection while reducing as much as 50% of the queueing delay experienced by a conforming connection. In addition, the neural fuzzy leaky bucket algorithm outperforms the fuzzy leaky bucket algorithm, in aspects of three performance measures such as selectivity, responsiveness, and queueing delay, especially when the traffic flow is bursty, dynamic, and nonstationary.

A QoS-aware policer for a fair resource sharing in wireless ATM

This paper deals with the Radio Resource Management (RRM) layer of future broadband systems capable to realize a wireless access to Asynchronous Transfer Mode networks. The interest here is in designing an efficient scheme operated by an access point to integrate demanding traffics, such as high-quality real-time video and interactive Web traffics. We adopt a time division multiple access air interface and we propose an original solution where a medium access protocol and a usage parameter control technique jointly define the radio resource management. In particular, we use a cyclic assignment scheme with a novel traffic policer based on fuzzy logic for video sources and on a token-bucket scheme for Web sources. Our technique is named Fuzzy Logic-Based Multiple Access (FLBMA) to remark the central function of the fuzzy policer. The FLBMA performance, derived through simulations, has highlighted the following interesting results: (i) very high capacity of video traffic sources in comparison with alternative RRM schemes; (ii) fair service of different traffic sources; (iii) video traffic Quality of Service independent of Web traffic load.

Efficient Transmission of MPEG-2 Coded Video Traffic over ATM Networks

Video traffic is expected to account for a significant share of the traffic volume in the future asynchronous transfer mode (ATM) networks. MPEG-2 proposed by Moving Picture Expert Group is one of the most promising compression techniques for such applications. One of the critical issues in MPEG-2 is to realize effective variable bit rate (VBR) video transfer thorough ATM networks. The Leaky Bucket (LB) scheme has been widely accepted as the usage parameter control (UPC) mechanism to police the VBR sources. We proposed a new Adaptive Dynamic Leaky Bucket (ADLB) congestion control mechanism, which is based on the LB scheme. Unlike the conventional LB, the leak rate of the ADLB is controlled using delayed feedback information of available bandwidth sent by the network. This scheme allows sources to get varying amounts of bandwidth over time, while reserving a minimum guaranteed bandwidth (MCR) for the entire duration of the connection. At the time of congestion, the leak rate of the ADLB is adjusted according to the feedback indicating the currently available bandwidth to the connection. The simulation results show that the end-to-end cell transfer delay and cell loss of each source has been improved significantly.

An integrated framework for traffic control in ATM networks based on soft-computing techniques

Abstract In this paper we assess the application of artificial intelligence techniques to the complex problem of traffic control in Asynchronous Transfer Mode (ATM) networks. The paper deals with the close link between Call Admission Control (CAC) and Usage Parameter Control (UPC) and proposes a simulation-based analysis to demonstrate how inefficiency on the part of policing affects bandwidth allocation. To take this into account, the paper proposes a framework for traffic control in which the CAC and policing functions are both based on artificial intelligence techniques, i.e., neural networks and fuzzy logic. A measurement-based CAC mechanism is then proposed and implemented by means of neural networks trained in such a way as to take into account the real behaviour of the policer. As the results obtained show, this allows us to implement traffic management strategies that can improve the exploitation of network resources.

Modeling and prediction of hybrid-coded variable bit rate video sources in fuzzy logic perspectives

This paper presents the modeling and prediction of variable bit rate video sources using fuzzy set and fuzzy logic theory. The sources are coded with the hybrid motion compensation/differential pulse code modulation/discrete cosine transform algorithm. The fuzzy logic prediction scheme discussed here is in the category of computational intelligence algorithms. It has the capability to handle statistically difficult to describe or unknown series. The proposed fuzzy logic prediction method is aimed at fast computation for online operation. It can be applied to the development of connection admission control, usage parameter control, and congestion control algorithms in multimedia communication networks.

The transmission of MPEG‐2 VBR video under usage parameter control

AbstractThis paper studies the transmission of MPEG‐2 VBR video over ATM network under usage parameter control. The idea is to seek a compromise between the network utilization and the quality of video service by applying UPC‐based rate control strategies to the video source. A modified leaky bucket algorithm is proposed to calculate the constraints on the bit‐rate guaranteeing conformance to peak cell rate, sustainable cell rate and burst tolerance usage parameters. Two rate control strategies, one for real‐time generated video coding and the other for pre‐compressed video, are proposed for MPEG‐2 VBR video. The rate control strategies control the video source to generate traffic conforming to the constraints on the bit rate. The experimental results show that both the UPC‐based rate control strategies can provide lossless transmission from the source perspective as well as to reduce the burstiness of the traffic. To keep within the bit‐rate allowed, the control method uses coarser quantization to maintain better picture quality than that by removing the number of AC transformed coefficients. The slight degradation of picture quality caused by the source rate control is preferable than the severe drop of picture quality caused by the cell loss at UPC. Copyright © 2001 John Wiley & Sons, Ltd.

Design of a multiple leaky buckets shaper

Asynchronous Transfer Mode (ATM) has been considered as the future trend for the information transfer in Broadband Integrated Services Digital Network (B-ISDN). ATM networks provide a guaranteed Quality of Service (QoS) for a variety of applications. One of the important QoS attributes is Cell Delay Variation (CDV). CDV measures how much delay variation will appear in cell transmission times. Call Admission Control (CAC) and Usage Parameter Control (UPC) are two main functions for achieving traffic control in ATM networks. The UPC scheme monitors and controls traffic in order to determine whether the established connections conform to the predefined parameters or not. For a real source operating at predefined parameters, some delay variation will occur in cell transmission times. CDV Tolerance (CDVT) controls the amount of acceptable deviation. Two classes of UPC methods have been proposed in the past to deal with CDV: one is to design an UPC method considering the worst traffic at User-Network Interface (UNI); the other is using a shaper for each connection of each link to accommodate CDV. In this paper, we propose a new shaper architecture to implement the UPC function that will eliminate CDV introduced between Terminal Equipment (TE) and the edge node of public networks. Our new shaper can follow multiple Generic Cell Rate Algorithm (GCRA) rules and consider all the traffic parameters. Furthermore, we use a simple method to reduce the memory requirement in the shaper. Insufficient memory might lead to incorrect cell departure in previous shapers. Simulation results show the performance is quite good and as expected.

Efficient bandwidth allocation and call admission control for VBR service using UPC parameters

Provision of Quality-of-Service (QoS) guarantees is an important and challenging issue in the design of Asynchronous Transfer Mode (ATM) networks. Call Admission Control (CAC) is an integral part of the challenge and is closely related to other aspects of network designs such as traffic characterization and QoS specification. Since the Usage Parameter Control (UPC) parameters are the only standardized traffic characterizations, developing efficient CAC schemes based on UPC parameters is significant for the implementation of CAC on ATM switches. In this paper, we develop a CAC algorithm called TAP (derived from TAgged Probability) as well as two other CAC algorithms using the UPC parameters. These CAC algorithms are based on our observation that the loss-probability-to-overflow-probability ratio tends to decrease as the number of sources increases. By introducing the loss-probability-to-overflow-probability ratio K, we find that this ratio sheds light on increasing resource utilization while still guaranteeing QoS. Analysis, simulation, and numerical results have shown that the proposed TAP algorithm is simple and efficient. Copyright © 2000 John Wiley & Sons, Ltd.

Performance evaluation of fair packet discarding in network with multiple bottlenecks

Fair packet discarding (FPD) is a mechanism which provides incentives to users for participation in congestion control, such that ATM networks can operate in a more efficient manner. The authors study the performance of FPD in a general network with multiple bottlenecks. By simulations. They show that the interaction between FPD and ATM Forum's explicit-rate flow control enables the packet-level throughput of each connection converging to the max-min fair apportionment in a distributed manner. With the built-in policing capability of FPD, the need of dynamic usage parameter control for ABR service is also eliminated.

Neuro-Fuzzy Modeling and Prediction of VBR MPEG Video Sources

The work presented in this paper intends to apply neuro-fuzzy methods for the modeling and prediction on traffic intensity of digital video sources which are coded with hybrid Motion Compensation/Differential Pulse Code Modulation/Discrete Cosine Transform (MC/DPCM/DCT) algorithm. Although current coding standards recommend constant bit rate (CBR) output by means of a smoothing buffer, the hybrid algorithm inherently produces variable bit rate (VBR) output. This paper describes the novel application of a fuzzy predictor for the purposes of modeling and prediction on video sources. The computation requirement of the fuzzy predictor and its neural network implementation are also discussed. The proposed fuzzy prediction method and its neural network version can be applied to the development of connection admission control, usage parameter control and congestion control algorithms in ATM networks.

Usage parameter control schemes for improving MPEG video quality over ATM networks

An MPEG encoder compresses moving pictures into I-, P-, and B-frames, where the most important I-frames generate traffic with the highest bit rate. For MPEG videos transmitted over ATM networks, invalid cells are discarded by a usage parameter control scheme at the user network interface and thus cause error propagation in both spatial and temporal domains. For spatial error propagation, the effect of a lost cell depends on the position located in a slice: the farther the position is, the lesser affected are the data. Besides, lost data near the edge of a screen is more tolerable than those at the central part. In order to improve the quality of the received video, we propose two methods to impute the violation of non-conforming cells to others located at a less important position of the same slice. Simulation results reveal that the quality is improved based on both PSNR and subjective visual feeling.

Letter effect of enhanced leaky bucket parameters on the maximum queue length: Worst‐case analysis

AbstractIn ATM networks, various usage parameter control (UPC) strategies are used to regulate incoming traffic according to the characteristics of the sources declared at call set‐up. Among these UPC schemes, the Leaky Bucket method is well‐known and has been discussed extensively. In this paper, we study the characteristics of the multiplexer in which cell arrivals are first policed by Enhanced Leaky‐Buckets (ELBs) before entering the system. In addition to both policing mean cell rate and peak cell rate, cell delay variation (CDV) are also taken into consideration for each ELB. We derive the upper and lower bounds on the maximum queue length expressed as a funtion of the ELB parameters and the number of sources. We also rigorously prove that these bounds occur with respect to a coincident token‐generating pattern and a perfectly interleaved token‐generating pattern, respectively.

Fuzzy Traffic Management for Modern Telecommunications

We describe applications of fuzzy logic in the area of broadband telecommunication networks. Call Admission Control (CAC) and Usage Parameter Control (UPC) play an important role in the traffic management of ATM networks (Asynchronous Transfer Mode). We present "fuzzy solutions" for this control tasks and we show their success by presenting simulation results and heuristic valuations.

Real-time estimation and dynamic renegotiation of UPC parameters for arbitrary traffic sources in ATM networks

This paper presents a robust and flexible real-time scheme for determining appropriate parameter values for usage parameter control (UPC) of an arbitrary source in an asynchronous transfer mode network. In our approach, the UPC parameters are chosen as a function of the statistical characteristics of the observed cell stream, the user's tolerance for traffic shaping, and a measure of the network cost. For this purpose, we develop an approximate statistical characterization for an arbitrary cell stream. The statistical characterization is mapped to a UPC descriptor that can be negotiated, with the network. The selected UPC descriptor is optimal in the sense of minimizing a network cost function, subject to meeting user-specified constraints on shaping delay. The UPC estimation scheme is extended to adapt to slow time-scale changes in traffic characteristics via dynamic renegotiation of the UPC parameters. We illustrate the effectiveness of our methodologies with examples taken from MPEG video sequences.

ATM traffic management considerations for facilitating broadband access

Traffic management in ATM nodes plays a key role in providing the capability to support a wide range of integrated services while utilizing network resources, such as buffer space and bandwidth, in an efficient manner. In many cases, the issues arising in ATM access devices are very similar to those encountered in larger ATM backbone nodes. In this article, major issues in the design of traffic management schemes are discussed. These include switch fabric design, buffering strategies, service scheduling disciplines, usage parameter control, buffer management schemes, call admission control, and feedback flow control.

An MPEG2-to-ATM converter to optimize performance of VBR video broadcast over ATM networks

This paper presents a novel MPEG2-to-ATM converter for VBR video broadcast over ATM networks. It functions as an external post-coding source rate controller between any MPEG2 source and an ATM network. Dynamic break points are employed to shape and partition the video data into high priority ATM cells which conform to the prevailing usage parameter control contract with the network, and nonconforming low priority cells which minimize the effects of cell loss due to network congestion on the subjective quality of the received video. Both high and low priority cells are transmitted over a common ATM virtual connection. Performance evaluations of actual VBR MPEG2 streams transmitted over a simulated converter and ATM network are presented to demonstrate the effectiveness of the proposed method.

Design of time‐differential GCRA enforcer and shaper in multi‐service ATM networks

AbstractAccording to the ITU‐T Recommendation 1.371, the Generic Cell Rate Algorithm (GCRA) is used to define Peak Cell Rate for the ATM network. It is further applied by the ATM Forum to define Sustainable Cell Rate and Burst Tolerance so as to facilitate Usage Parameter Control and Network Parameter Control. To check the validity of a cell according to the declared traffic parameters, the enforcer must read die clock time when a cell arrives. However, the clock of the enforcer would roll over frequently and thus makes wrong judgment. On the other hand, for a shaper in a customer premise node to dispatch cells conforming to the declared parameters, the clock would also roll over and the cell would not be dispatched correctly. To overcome the problems introduced by clock roll‐over, we propose two modified GCRAs for the enforcer and the shaper, respectively. According to the proposed algorithms, we design new architectures for multi‐connection shapers and enforcers in which a cell's priority is also considered. We also prove that the proposed algorithms are justified for the proposed architectures.

Performance analysis of backpressure congestion control: Preliminary case

In ATM networks, preventive control is widely recognized as a way to avoid congestion efficiently, and it is implemented by a conjunction of call admission control (CAC) and usage parameter control (UPC). However, since congestion may still happen because of unpredictable statistical fluctuations of traffic injected into networks, it would be effective to relieve congestion using reactive control together with preventive control. In this paper, we investigate the performance of backpressure control which is a reactive control scheme with an analytical approach. Moreover, we propose backpressure control with cell pushout scheme to overcome some weaknesses of backpressure control. Numerical results show that the control with push-out scheme improves cell loss performance, without increasing delay too much.

Bounds on waiting time for multiplexing leaky bucket enforced sources in ATM networks

In ATM networks, various usage parameter control (UPC) strategies are used to regulate incoming traffic according to the characteristics of the sources declared at call set-up. Among these UPC schemes, the leaky bucket method is well known and has been discussed extensively. The authors study the characteristics of the multiplexer in which cell arrivals are first policed by enhanced leaky buckets (ELBs) to police mean and peak rates simultaneously. Based on the criteria of delay experienced in the buffer, they derive the upper and lower delay bounds expressed as a function of the ELB parameters and the number of sources. They also rigorously prove that these bounds occur with respect to a coincident environment and a perfectly interleaved environment, respectively.