Hong-Bin Chiou

Performance of ATM switches with age priority packet discarding under the on-off source model

In the current ATM AAL5 implementation, even a single cell loss event can lead to the corruption of one whole packet. Hence, it has been observed that the throughput of the upper layer protocol may easily collapse on a congested ATM network. We propose a buffer management method called age priority packet discarding (APPD) scheme to be used along with two other schemes: the early packet discarding (EPD) and the partial packet discarding (PPD) schemes. After describing the operations and the pseudo code of the proposed APPD scheme and how it operates with the EPD/PPD schemes, the packet level QoS of APPD and its extended versions are derived analytically under homogeneous on-off source model. Numerical results obtained via, analytical approach suggest that the proposed APPD scheme can more effectively and fairly reduce the packet loss probability than other schemes.

A novel ATM traffic scheduler for real-time multimedia data transport with improved packet level QOS

In this paper, we propose an efficient scheduling scheme called multi-layer gated frame queueing (MGFQ) for real-time traffic over ATM networks. ATM switches equipped with the function of MGFQ which employs only one set of FIFO queues can provide real-time multimedia communication with a wide range of QoS requirements. In addition, a hybrid design which combines MGFQ scheme with an age priority packet discarding (APPD) scheme is proposed to enhance packet level QoS. The simulation results show that the cell level performance as well as the packet level QoS can be improved simultaneously when applying this hybrid design.

The design of an efficient traffic scheduler with fair bandwidth-sharing for wireless multimedia services

The generalized wireless differentiated fair queueing (GWDFQ) algorithm is proposed to accommodate delay/jitter controls, and fair residual bandwidth sharing for real-time and non-real-time traffic streams simultaneously. The location-dependent channel error property, as appeared in most wireless networks, are considered in the algorithm and the temporary short error burst are compensated by the design of credits. The simulation results show that GWDFQ can achieve excellent performance, including timely delivery of real-time traffic, virtually loss-free transmission of non-real-time traffic, and fair usage of channel bandwidth among remote stations.

Enhancing the fairness of TCP over Internet using an improved hierarchical packet fair queueing scheme

We proposed an improved hierarchical packet pair queueing (H-PFQ) mechanism, using ACK Spacing, for effective bandwidth management of TCP traffic over ATM networks. According to the pre-determined bandwidth sharing and the class hierarchy of all TCP sessions, we design on algorithm to calculate the required time intervals between consecutive ACK packets of each TCP session to avoid packet drops due to buffer overflow. We demonstrated via computer simulations that the proposed improvement techniques may result in much better performance than the original H-PFQ mechanism used in the forward direction in the sense that not only the effective throughput of the bottleneck link is improved but also the fairness among TCP sessions can be maintained.

Steady-state analysis of rate-controlled data transport in ATM Local Area Networks

This paper presents a steady-state analysis of rate-based flow control operating with the regular window mechanism of the transport protocol in ATM local area network (LAN) or local high-speed network environments. The rate control schemes are divided into single-threshold and two-threshold cases. By applying Nortons theorem for queuing model simplification and deriving a computation algorithm, the analytical results for steady-state performance of these schemes are found to be computationally efficient and yield accurate approximations. In the numerical results, the rate control schemes have been shown to have significant effects in reducing congestion levels at the receiving entity as well as in the high-speed networks. We also conclude that the two-threshold rate control scheme can be more effective in alleviating network congestion conditions than single-threshold control, while keeping the control overhead (in terms of the rate adjustment frequency) at a low level, provided that threshold values are selected appropriately. The total throughput could be affected, but only in a limited fashion.

An efficient ATM traffic scheduler for supporting multimedia services with improved packet level QoS

We propose a novel and efficient traffic scheduling scheme called multi-layer gated frame queueing (MGFQ) to support real-time multimedia services in the ATM networks. MGFQ employs only one set of FIFO queues to provide a wide range of QoS for real-time applications over ATM networks. We also propose a hybrid design to allow MGFQ to combine its scheduling scheme with age priority packet discarding (APPD) scheme. For this hybrid design, the cell level performance as well as the packet level QoS can be improved at the same time. Simulation results show that this hybrid design will be useful for packetized voice and progressive layer-compressed video transmission across the backbone networks. With MGFQ, a receiver can allocate less resources to compensate the disturbed cell arrivals.