Showing papers on "Fast packet switching published in 1984"

The Spatial Capacity of a Slotted ALOHA Multihop Packet Radio Network with Capture

Abstract: In this paper we determine throughput equations for a packet radio network where terminals are randomly distributed on the plane, are able to capture transmitted signals, and use slotted ALOHA to access the channel. We find that the throughput of the network is a strictly increasing function of the receiver's ability to capture signals, and depends on the transmission range of the terminals and their probability of transmitting packets. Under ideal circumstances, we show the expected fraction of terminals in the network that are engaged in successful traffic in any slot does not exceed 21 percent.

Self-routing packet switching network with intrastage packet communication

Abstract: A communication method and packet switching network in which self-routing packets are communicated through the network by intra-communication of the packets within stages of the network as well as inter-communication of the packets among stages. The stages each having a plurality of pairs of switch nodes with each pair having an intra-node link between the pair of nodes. Each of the switch nodes comprises input controllers and output controllers. The input controller of a node is responsive to the receipt of a packet for interrogating the address field of the packet to determine the destination of the packet. The input control on the basis of the destination determination commmunicates the packet towards the destination via either an inter-stage link or an intra-node link on the basis of availability of the links and an internal control circuit. If a packet is transmitted via an intra-node link to the paired node the latter then transmits the packet via its output controller to the next stage via an inter-stage link. If both the intra-node link and the inter-stage link are available, the internal control circuit then determines which link should be utilized in communicating the packet. The internal destination circuit performs this designating function on the basis of a random number generator.

Adaptive preferential flow control for packet switching system

Abstract: Flow control of data packets through a packet switching network (20) to reduce congestion is controlled by an adaptive preferential permit packet (APP) processing from an originating data terminal (10) through each packet switch node of the network to a destination data terminal (11). APP requires less buffer storage capacity at each switch node, and enables data packets to enter the network only when there is a permit packet indication that the data packets are likely to reach, and be accepted by, their destination. The permit packet is sent node to node (16-19, 25, 28) prior to a transmission of a bulk of data packets. Each node is equipped to queue buffer (12-15, 21-24) a permit packet on a preferential basis ahead of data packets. The node discards the permit packet if the number of packets awaiting transmission from that node exceeds a prescribed threshold. This is throttling process, since the originating port times out and resends a permit packing if a permit-return packet is not received within a predetermined time. Permit-return packet processing, adaptive time-out controls, and preferential treatment of permit packets are disclosed.

Packet Switching Networks for Multiprocessors and Data Flow Computers

Abstract: Most packet switched multistage networks have been proposed to use a unique path between any source and destination. We propose to add a few extra stages to create multiple paths between any source and destination. Connection principles of such multipath networks for packet switching are presented. Performance of such networks is analyzed for possible use in multiprocessor systems or in data flow computers.

Packet communication systems

Abstract: In a packet communication system of a multiaccess type in which a single communication medium is used commonly and divided into a plurality of channels, respective users observe states of the channels and the probability of packet transmission to respective channels is controlled in accordance with observed information, respective users are assigned parameters corresponding to respective channels and the probability of packet transmission onto the channels is controlled according to the parameters, a dummy packet is continuously transmitted for a predetermined time at in channels having low utilization factors, for data requiring immediate transmission. In a modification, a setup packet is sent for data requiring immediate transmission. All the users determine whether the received packet is the setup packet and the set the stored parameters. Accordingly, in another modification, a setup packet is transmitted for data requiring immediate transmission and a dummy packet is continuously transmitted in a channel for which the origination setting packet is successful.

Performance Evaluation of a Packetized Voice System--Simulation Study

Abstract: Introduction of the packet switching technique into digitized voice communication may afford great advantages in efficient use of the channel, compared to both circuit-switched and DSI systems. Detailed characteristics, however, have not been obtained because of difficulty in the exact analysis. Hence, simalation models are developed in this paper for the packetized voice transmission system, and various characteristics such as tranmission delays and loss probability of voice packets are obtained. We further evaluate three types of voice packet reassembly strategy at the receiving terminal, and obtain the optimal packet length, which keeps both overall packet transmission delay and packet loss probabilty less than a certain permissible value. Comparison among three strategies is also stated.

Packet exchange data transmission system

Abstract: At least two packet exchangers are interconnected through an external transmission line to transmit a data packet. Each packet exchanger comprises a main controller for processing the data packet sent from a packet terminal, in a data link level and a packet level, and a connecting unit for sending the data packet sent from the main controller to the external transmission line and sending the data packet sent from the external transmission line to the main controller.

Quasi cut-through: New hybrid switching technique for computer communication networks

Abstract: A novel hybrid switching technique for computer networks is proposed and analysed in this paper. This hybrid switching technique combines packet switching and cut-through switching. Partial cuts are introduced to improve the performance of a network from a practical point of view. Messages are segmented into packets using a threshold-based segmentation rule. A method to calculate reassembly delay for noisy channels is described and has been used in the analysis of the hybrid switching. Several numerical results are reported at the end which depict the practical versatility of the proposed hybrid switching. Some simulation results are also reported in order to verify the analytical formulation.

The Behavior of a Finite Queue with Batch Poisson Inputs Resulting from Message Packetization and a Synchronous Server

Abstract: This paper studies the behavior of a packet switch which provides finite waiting space and receives packetized messages. The arrivals of the messages constitute a Poisson process. Each message consists of a random number of packets. The number of packets contained in a message is assumed to be an integer-valued random variable which may follow any arbitrary probability distribution. All packets residing in the buffer receive service from a single output transmitter operating synchronously at a constant rate. Each packet receives the same fixed service time from the transmitter and then leaves the system. Upon the arrival of a message, if the remaining buffer space is not enough to accommodate all packets of the message, then the entire message is completely rejected. Results such as message blocking probability, packet blocking probability, throughput, and mean delay have been obtained. Two different approaches, minislot approximation and the application of the residue theorem, are used to obtain these results. Especially, this combinatorially very complex problem is successfully solved by the residue theorem in a recursive manner. These results are useful in evaluating the performance of a packet switch. They are also useful for design purposes.

Performance evaluation of a protocol for packet radio network in mobile computer communications

Abstract: The need to provide computer network access to mobile terminals and computer communications in the mobile environment has stimulated and motivated the current developments in this area. Packet radio technology has developed over the past decade in response to the need for real-time, interactive communications among mobile users and shared computer resources. In computer communication systems we have a great need for sharing expensive resources among a collection of high peak-to-average (i.e., bursty) users. Packet radio networks provide an effective way to interconnect fixed and mobile resources. The results of an attempt to study the performance of the mobile packet radio network for computer communications over degraded channels are presented. We develop a model under fading conditions and derive a protocol for evaluating the performance of the mobile packet radio network (MPRNET) in terms of the packet error rate, packet delay, throughput and average number of retransmitted packets per cycle. The analytical results are presented and numerical examples are given to illustrate the behavior of these performance criteria as a function of packet transmission rate, packets transmitted per cycle, packet size, and vehicle speed with the help of appropriate plots.

Digital switching system

Abstract: A hierarchical message channel storage of a digital switching system which is connected to time division multiplex transmission lines includes at least a small-capacity high-speed memory and a large-capacity low-speed memory. A control section performs switching using the high-speed memory when a circuit switching call is received. However, when a packet switching call is received, the control section accesses the high-speed memory to temporarily store transmission data in the high-speed memory and performs switching for one of the output transmission lines or the control section accesses the high- and low-speed memories to temporarily store data in the low-speed memory through said high-speed memory so as to perform switching for one of said output transmission lines. In this case, the access cycles of the high-speed memory have circuit/packet switching call cycles and switching program cycles. A single storage is commonly used for the circuit switching call requiring writing data at a high speed, the packet switching call requiring storing a great amount of data, and the switching program.

Multiplexed digital data transmission

Abstract: A digital transmission system for transmitting, e.g., television sound has two packet type indicators indicating, e.g., mono/stereo transmission. Normally the same packet type indicator is transmitted for a long sequence of packets. To provide synchronising information to enable, e.g., appropriate timing of the sound signal to the associated video signal, the packet type indicator for a single packet is changed to an indicator which is inappropriate to the packet concerned but is appropriate to another type of packet.

Connection principles for multipath, packet switching networks

Abstract: Packet switched Multistage Interconnection Networks (MINs) have been mostly proposed to use unique connection path between any source and destination. We propose to add a few extra stages in an MIN to create multiple paths between any source and destination. Connection principles of Multipath MINs (MMINs) for packet switching are presented in this paper. Performance of such network is analyzed for possible use in multiprocessor systems and dataflow computers. For an MMIN with n nodes, the number of required stages is confined in the range [log2n+1, 2log2n-1]. Each stage consists of n/2 buffered 2-by-2 switching cells. In practice, one or two extra stages is sufficient beyond log2n stages required in a unique-path MIN. The delays of MMINs are shown much shorter than that of using unique-path MINs for packet switching. The improvement lies in significantly reduced packet wait delays in buffers, especially under heavy traffic conditions. The tradeoffs between reduced network delays and increased hardware cost are studied. Optimal design criteria and procedures are provided for developing MMINs with a fixed network size and stages.

Congestion control system in packet switching network

Abstract: PURPOSE:To enable shortening of packet transfer time and dispersion of load in a packet switching network by determining passage of sending out packet depending on alternative control information added to the packet and information of the state of congestion of adjoining packet exchange which is on the passage to destination when a relaying packet exchange received the packet. CONSTITUTION:In a transfer packet, alternative control information (cr) is added besides destination information (dn) and originating station information (on) to terminal transmitting packet (pkt). The alternative control information (cr) is set to logical value ''0'' to general packet that makes a detour to a packet exchange which is in the state of congestion, and set to logical value ''1'' to specific packet that does not make a detour. The relaying packet exchange A discirciminates alternative control information (cr) of arriving packet, and when it is set to logical value ''1'', sends out the packet to a relaying path L2 even when it is receiving congestion notice packet from a packet exchange B. Consequently, the packet is transferred to destination packet exchange C by the shortest route similar to the case where the packet exchange B is not in the state of congestion.

A Three-Node Packet Radio Network

Abstract: A two-hop packet radio network consisting of three nodes is considered. The three nodes have infinite buffers and share a common radio channel for transmitting their packets. Two of the nodes forward their packets to a third node that acts as a source of data as well as a relay that forwards all the packets entering the network to a main station. We assume that two of the nodes are granted full rights in accessing the channel while the third node uses a random access scheme. For this network we derive the condition for steady state and the generating function of the joint queue length distribution at the nodes in steady state. We also give several numerical examples and compare the performance of the network with and without a relay node.

Line exchange switch with packet exchange function

Abstract: PURPOSE: To reduce the delay time in packet transmission by adding a packet exchange function to a time division spatial switch. CONSTITUTION: In case of packet exchange, to which incoming packet exchange a packet incoming from an input terminal 12 is transferred is decided, the packet is re-edited into an inter-network packet. When the inter-network packet is transmitted in a time division spatial switch SW3 and a packet display bit P is logical 1, the inter-network packet is extracted from an incoming highway 2 and received, and transmitted to packet buffers 331∼33M according to a destination address D. A packet selector 35 extracts the inter-network packet and transmitted to an output highway 4. An incoming packet exchange 5 extracts the inter-network packet, reproduces it into the original packet and the result is outputted from a packet exchange output terminal 53. COPYRIGHT: (C)1986,JPO&Japio

Method for controlling a multistage space switching network

Abstract: This invention is a cost efficient method for controlling a multistage space switching network for high voltage applications. This method minimizes the number of control signal leads required to operate a multistage space switching network. If a switching network has N space switching stages, then the present invention provides for performing the space switching function with N+1 control signal leads. The present space switching method may also be employed for conventional non-high voltage space switching applications.

Route selecting system of packet switching network

Abstract: PURPOSE:To reduce a packet transfer time, and to improve an efficiency of a trunk line by dividing each packet flowing into a packet switching network, into groups, with regard to a transmitting packet exchange, and adding group discriminating information to each packet so that each repeating packet exchange can select a transfer route based on the added group discriminating information. CONSTITUTION:In a packet transferred from a switchboard, not only addressed station information (dn) and transmitting station information (on) but also traffic group discriminating information (tg) are added to a transmitting packet (pkt) of a terminal. When a terminal equipment T1 transmits a packet destined for a terminal equipment T3 contained in a packet switchboard D, to a packet exchange, a traffic group discriminating part TS provided in a central control equipment CC discriminates a fact that the transmitting terminal equipment T1 belongs to the first track group, and informs its fact to a route selecting part SEL'. The route selecting part SEL' refers to addressed station information (dn)=D corresponding part decided from the received packet, checks a congested state of trunk lines L1, L2, and if the trunk line L1 is in the congested state, the trunk line L2 being the second priority route is selected as a packet transfer route.

A High Performance Satellite Baseband Switching Technique

Abstract: This paper describes the basic configuration, VLSI implementation, and throughput of a novel switching technique applied to a satellite baseband switch. The described switching technique efficiently switches wideband, circuit switched, packet, and burst' traffic in a satellite TDMA environment, and also has favorable attributes for efficient VLSI implementation. VLSI attributes include a highly concurrent architecture that can be implemented from a relatively small set highly repeated small scale cells, with all data transfers occurring over short parallel interconnections between cells. The switching sytem is formed from single stage VLSI "ring" switches that can operate in parallel to increase throughput, provide redundancy, and reduce chip/wafer speed and density requirements. When switching burst traffic, this baseband satellite switching technique can operate without ground based control of the switching process, giving it important survivability advantages.

Packet Satellite Networks

Abstract: Packet satellite networks combine the advantages of packet switching for channel sharing with those of satellites for long-haul broadcast capability. This paper describes the packet satellite technology as developed by DARPA and demonstrated in two systems based on channels provided by INTELSAT and WESTAR satellites, respectively.