Lower Packet Delay Research Articles

Packet transfer delay analysis of the N nodes RPT rings in the cut-through architecture

We discuss an analytical approximation for high and low priority packet delay in the cut-through architecture of the N nodes resilient packet transport rings based on the queuing theory. It turns out that both low priority traffic packet delay and high priority one increase with the node number N of the RPT rings, and low priority traffic has larger packet delay than high priority traffic at the same node number N, and when N tending to infinity, the maximum transfer delay is the twice of average delay.

Packet-scheduling algorithm based on priority of separate buffers for unicast and multicast services

A new integrated packet-scheduling algorithm that handles both unicast and multicast traffic concurrently by using two logically divided buffers in each input port is proposed. Computer simulations show that the proposed scheme gives not only low average output packet delay, but also low output packet delay variance for packets with different fan-outs.

Design and Analysis of a Channel Access Protocol for WDM-Based Single-Hop Optical Networks*

We propose a channel access protocol for single-hop wavelength division multiplexing (WDM) optical networks. Each node is equipped with a fixed-tuned transmitter, a tunable transmitter, a fixed-tuned receiver, and a tunable receiver. The proposed protocol alleviates the drawbacks of a previous protocol [1], e.g., invalid data transmissions that follows receiver collisions and possible acknowledgment packet collisions with header/data packets, while retaining many advantages. As a result, the network performance in terms of throughput and packet delay is improved. Analytical models based on the timing diagram analysis, the continuous-time Markov chain, and the randomization technique are developed to assess the proposed protocol, and are validated through event-driven simulation. The performance is evaluated in terms of channel utilization, mean packet delay, and packet delay distribution with variations in the number of nodes, the offered traffic, the size of data packets, and the network propagation delay. Through numerical results and simulation studies, we show that the proposed protocol achieves better channel utilization and incurs lower packet delays.

WDM/SCM multiple access protocol with high throughput and low packet delay for passive double star networks

This paper investigates a hybrid wavelength division multiplexing (WDM) multiple access protocol combining the advantages of preallocation and reservation-based schemes using a subcarrier multiplexing (SCM) technique for passive double star optical networks. We include a node-grouping scheme in the proposed protocol to increase channel utilization and to reduce sensitivity to queueing delay time and propagation delay time. All nodes in a network are connected through passive star sub-hub forming multiple groups, and the groups are then connected through a central passive star hub resulting in a passive double star network. Each group is pre-assigned a WDM channel as its home channel, and a specific SCM channel identifies each node. In the proposed protocol, the frame is divided into slots corresponding to the number of groups, not the number of nodes. The reduced number of slots results in reduction of queueing delay time. Furthermore, additional reduction in the propagation delay time of the control packets is achieved by limiting the propagation paths of the control packets to the roundtrip between source nodes and sub-hub in a double star network.

Improving TCP performance over wireless networks at the link layer

We present the transport unaware link improvement protocol (TULIP), which dramatically improves the performance of TCP over lossy wireless links, without competing with or modifying the transport- or network-layer protocols. TULIP is tailored for the half-duplex radio links available with today's commercial radios and provides a MAC acceleration feature applicable to collision-avoidance MAC protocols (e.g., IEEE 802.11) to improve throughput. TULIP's timers rely on a maximum propagation delay over the link, rather than performing a round-trip time estimate of the channel delay. The protocol does not require a base station and keeps no TCP state. TULIP is exceptionally robust when bit error rates are high; it maintains high goodput, i.e., only those packets which are in fact dropped on the wireless link are retransmitted and then only when necessary. The performance of TULIP is compared against the performance of the Snoop protocol (a TCP-aware approach) and TCP without link-level retransmission support. The results of simulation experiments using the actual code of the Snoop protocol show that TULIP achieves higher throughput, lower packet delay, and smaller delay variance.

Multidestination communication over tunable-receiver single-hop WDM networks

We address the issue of providing efficient mechanisms for multidestination communication over one class of lightwave wavelength division multiplexing (WDM) architectures, namely, single-hop networks with tunability provided only at the receiving side. We distinguish a number of multicast traffic types, we present a number of alternative broadcast/multicast time-division multiple-access (TDMA) schedules for each type, and we develop heuristics to obtain schedules that result in low average packet delay. One of our major contributions is the development of a suite of adaptive multicast protocols which are simple to implement, and have good performance under changing multicast traffic conditions.

A high-performance input access scheme for ATM multicast switching

In this paper, we propose an input access scheme for input-queued ATM multicast switches, achieving high system throughput, low packet delay and packet loss probability. Multicast and unicast packets of each input port are separately queued. Multicast queues take priority over the unicast queues, and both types of queues are fairly served in a cyclic-priority access discipline. In particular, each unicast queue is handled on a window-service basis, and each multicast packet is switched in a one-shot scheduling manner. To evaluate the performance of the access scheme, we propose an approximate analysis based on a simplified cyclic-priority model for anN×N finite-buffer multicast switch possessing Bernoulli multicast and unicast arrivals, with window-service (for unicasting) and one-shot scheduling (for multicasting) both taken into account. Finally, we show simulation results to demonstrate the accuracy of the approximate analysis and the superiority of the scheme over existing schemes with respect to normalized system throughput, mean packet delay, and packet loss probability.

Paris: An approach to integrated high‐speed private networks

AbstractThis paper describes a design of a high‐speed packet switching system for integrated voice, video and data communications. The system makes use of a simplified network architecture in order to achieve the low packet delay and high nodal throughput necessary for the transport of voice and video. A prototype of this system has been implemented and is now being tested under a variety of packet traffic loads. We have demonstrated that this system provides a cost‐effective solution for private integrated networks.

Packet Voice on a Local Area Network with Round Robin Service

In this paper, we propose a combined voice/data protocol suitable for multiple access broadcast networks that provide round robin service to the stations. Such networks are well suited to the integration of voice and data since they guarantee bounded delay and provide high utilization even for high bandwidth channels. Using one such network proposal-namely Expressnet-as a representative scheme, we examine the characteristics of the service that voice traffic experiences under the voice/data protocol. We show that the access protocol is able to utilize the channel efficiently to support a large population of voice sources while maintaining low packet delay and guaranteeing some prespecified minimum bandwidth for data traffic. In addition, we show the advantages of silence suppression, i.e., discarding speech that constitutes silent periods, and we examine the cost of overloading the network in terms of the amount of speech discarded.

Distributive Demand-Assigned Packet Switching with Trailer Transmissions

In a packet satellite system using ALOHA type random access techniques, channels and on-board processing may be effectively used to provide significant gains in throughput, delay, and bandwidth efficiency. Motivated by this conjecture, a distributive demand-assigned packet broadcast system through a processing satellite with multiple request channels and user buffers is first presented. This scheme is shown to be able to achieve the above goals except, as any other demand type scheme, it also exhibits relatively poor delay performance at low traffic when compared with pure random access schemes. An extended scheme using trailer transmission to improve delay performance at low traffic is then introduced. Two techniques for handling trailer transmissions are studied and compared. Both are shown to provide lower packet delay at light trafric. lay at light traffic.